Bioenergy

Biomelioration:

Harnessing Biomethanation for Energy Generation & Environment Protection:

Sardar Taimur Hyat-Khan. Email: [email protected] web: www.tamir-e-nau.org 1

Organic Waste

Bio-Gas Plant

Methane +Soil Amendment

http://www.tamir-e-nau.org/

mailto:[email protected]



Table of Contents:1. Introduction: ...........................................................................................................6

1.1 Definitions:.........................................................................................................61.1.1 Liquid Waste:.............................................................................................61.1.2 Biomelioration: .........................................................................................61.1.3 Bioenvironmental Management: .............................................................61.1.4 Bioremediation:..........................................................................................61.1.5 Methanogenesis:.........................................................................................61.1.6 Bioaugmentation: ......................................................................................61.1.7 Phytoremediation: ....................................................................................61.1.8 Bio-Oxidation: ...........................................................................................71.1.9 Composting: ..............................................................................................7

1.2 The History of Methane:...................................................................................71.3 Reasons for Failures:.........................................................................................81.5 What’s Different Now?......................................................................................81.5 Advantages & Disadvantages:..........................................................................91.5.1 Advantages:................................................................................................91.5.2 Disadvantages.............................................................................................9

2. Liquid Waste:.......................................................................................................102.1 Households: .....................................................................................................122.2 Service Industries: ..........................................................................................132.3 Manufacturing Industry: ...............................................................................132.3.1 Waste Stream or Wastes having as Constituents:................................142.3.2 Other Hazardous Waste Streams: ........................................................16

2.4 Hazardous Waste Management:....................................................................162.4.1 Hazardous Waste Characteristics:.........................................................162.4.2 Bioaugmentation Treatment Materials:................................................17

3. Health Issues:.......................................................................................................223.1 Major Excreta Related Diseases:...................................................................223.2 Excreta Related Diseases and their Characteristics:....................................233.3 Survival Time of Pathogens by different Disposal Treatment Conditions.24

4. Managing the Use of Water:...............................................................................244.1 BACT: ..............................................................................................................244.2 The Sustainable Region Initiative (SRI): ......................................................244.2.2 Integrated Resource Recovery:..............................................................254.2.2 Use Liquid waste as a Resource:............................................................26

4.3 Water Treatment Projects Design Philosophy for Developing Countries: 285. Biological Treatment:..........................................................................................29

5.5 Wastewater Treatment Plants:.......................................................................305.2 Methane:...........................................................................................................305.2.1CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −891 kJ/mol (at standard conditions)). .30

5.3 Methanogenesis:...............................................................................................32Strains of Methanogens:................................................................................................325.4 Thermophillic Digesters:..................................................................................335.5 Energy:...............................................................................................................33






5.5.1 Daily Waste and Methane Production by Dairy, Beef:........................355.5.2 Waste Methane Contents and Petrol Equivalents:...............................365.5.3 Developing Technologies:........................................................................36

5.6 Safety:...............................................................................................................365.7 Composition:....................................................................................................365.8 Fertilizer and Soil Conditioner:....................................................................37 5.9 Waste Heat Recovery:.....................................................................................375.10 Biochemical Process:.......................................................................................375.11 Physical Process:..............................................................................................385.12 Alternative Biological Production routes:.....................................................38

6. Generation Process:.............................................................................................386.1 Optimum Conditions for Digester Operation:..............................................386.2 System Management: .....................................................................................396.2.2 Preferential Degradation of Specific Compounds: ..............................396.2.3 Improved Nitrification ...........................................................................396.2.4 Other Areas: ............................................................................................396.2.6 Method: ....................................................................................................39

6.3 Gas Production. ...............................................................................................406.3.1 pH: ............................................................................................................406.3.2 Ammonia Concentration: ......................................................................406.3.3 Uniform loading:......................................................................................416.3.4 Key Consideration:..................................................................................416.3.5 Important Issue:.......................................................................................416.3.6 Establishment: .........................................................................................426.3.7 Suitability of Raw Material:...................................................................426.3.8 Percentage of Solids:................................................................................426.3.9 Temperature of Operating Cycle:..........................................................42

6.4 Digester Construction Requirements:...........................................................426.5.1 Insulating: ................................................................................................426.4.2 Stirring: ...................................................................................................42

6.5 Digester Innovations:.......................................................................................436.5.1 Corn Cob Digesters..................................................................................436.5.2 Energy Dome............................................................................................44

7. “Makeen Qatil Makanoon Kay”........................................................................447.1 Standing on the Outside, Looking In:............................................................457.2 Present Trends:................................................................................................457.2.1 “Israaf:”....................................................................................................457.2.2 Eco-Disaster:............................................................................................457.2.3 Unaesthetic:..............................................................................................457.2.4 Un-Scientific:............................................................................................457.2.5 Expensive:.................................................................................................457.2.6 Non-Traditional:......................................................................................457.2.7 Site-Orientation:......................................................................................467.2.8 Energy Conservation:..............................................................................467.2.9 Thermal Characteristics:........................................................................467.2.10 Earth Shelter:...........................................................................................47






7.2.11 Roof:..........................................................................................................477.2.12 Walls:........................................................................................................477.2.13 Floors:.......................................................................................................477.2.14 Basements:................................................................................................477.2.18 Prevailing Adobe Homes:........................................................................487.2.19 Geodesic Dome Construction:................................................................487.2.20 Weather/ Climate Orientation:..............................................................497.2.21 Location:...................................................................................................497.2.22 Summary:.................................................................................................49

7.3 Concept: ...........................................................................................................497.3.1 Effort: .......................................................................................................507.3.2 Other Uses: ..............................................................................................507.3.3 The Design: ..............................................................................................507.3.4 Culture: ....................................................................................................507.3.5 Structure: .................................................................................................507.3.6 Designing and Trials: .............................................................................51

8. Size of the Plant:..................................................................................................518.1 Sizing a Bio Gas Plant.....................................................................................518.2 Summary..........................................................................................................528.3 Double Stage: ..................................................................................................53

9. Residual Products: ..............................................................................................549.1 Class A Sludge: ...............................................................................................549.1.1 Composting the Digestate:......................................................................55

9.2 Gas Contamination and Contaminants: .......................................................559.3 Purification of Landfill and Digester Gas: ...................................................579.3.1 Gas Scrubbing Technologies:.................................................................58

10. Determining the Feasibility of Methane Production:.......................................6111. Conclusion:...........................................................................................................63

Table of Tables:Table 1: Sewage Capacity...................................................................................................5Table 2: History of Methane................................................................................................6Table 3: Reasons of Failure.................................................................................................7Table 4: What's Different Now!..........................................................................................7Table 5:Advantages.............................................................................................................8Table 6: Disadvantages........................................................................................................8Table 7: Sewage Statistics.................................................................................................10Table 8: Liquid Waste Sources..........................................................................................11Table 9: Food Group Disposal via Sink/ Sewer................................................................12Table 10: Leather Industry Effluent Analysis...................................................................12Table 11: Industrial Hazardous Liquid Waste Categories.................................................13Table 12: Industrial Waste Constituents............................................................................13Table 13: Explosives Waste Constituents..........................................................................16Table 14: Explosives Waste Degradation Products...........................................................17Table 15: Bioaugmentation Treatment Materials..............................................................17Table 16:Proposed Bioremediation Process......................................................................18Table 17: Major Excreta Related Diseases........................................................................22






Table 18: Excreta Related Diseases & Characteristics......................................................22Table 19:Pathogen Survival Times by Disposal/ Treatment.............................................23Table 20: Best Available Control Technology (BACT) 3Rs.............................................23Table 21: Overarching Principles......................................................................................24Table 22: Sustainability Principles....................................................................................24Table 23: Design Philosophy Indicators............................................................................26Table 24: Technology Imperatives....................................................................................27Table 25: Conditions for High Quality Water Production.................................................27Table 26:Methane Combustion Process Equations...........................................................29Table 27: Use & Consumption of Biogas..........................................................................33Table 28: Dry Manure Methane Production......................................................................34Table 29: Waste Methane Contents & Petrol Equivalents................................................34Table 30: Methane Composition & %...............................................................................35Table 31: Ammonia Concentration Effect on Methane Production..................................39Table 32:C:N Ratios..........................................................................................................40Table 33: Orientation Factors............................................................................................44Table 34: Energy Conservation.........................................................................................45Table 35: Current Adobe Construction Climatic Adaptation Advantages........................46Table 36: Current Adobe Construction Climatic Adaptation Disadvantages....................47Table 37: Gedesic Dome Construction Advantages..........................................................47Table 38: Advantages of Proposed Construction..............................................................48Table 39: Methane Production Residual Products.............................................................52Table 40: Digestate Composting Advantages....................................................................53Table 41: Gas Purification Reasons...................................................................................56Table 42: Purification Process...........................................................................................58Table 43: PSA Scrubbing Advantages..............................................................................59

Table of Figures:Figure 1: Gas Street Lamp.................................................................................................8Figure 2: Geodesic Digesters.............................................................................................9Figure 3: Green House Gasses.........................................................................................10Figure 4: Liquid Waste....................................................................................................10Figure 5: Sewerage Systems Components.......................................................................12Figure 6: Treatment Perspective......................................................................................20Figure 7: Sustainable Resource Initiative........................................................................27Figure 8: Wastewater Treatment Stages..........................................................................30Figure 9: Biochemical Process........................................................................................37Figure 10: pH Effects.........................................................................................................40Figure 11: Stirrer................................................................................................................43Figure 12: Geodesic Dome Bamboo Frame......................................................................44Figure 13: Sizing a Digester..............................................................................................51Figure 14: Flow Chart Waste Disposal..............................................................................53Figure 15: Large Scale Composting..................................................................................55Figure 16: Digester Gas Contents......................................................................................55Figure 17: Wet Scrubbing..................................................................................................58Figure 18: PSA Cycle.......................................................................................................59Figure 19: PSA..................................................................................................................59






Figure 20: Moving Towards the Future.............................................................................631. Introduction: Sewage infiltration into groundwater has made most of the world’s potable water undrinkable, unless immediate and emergency measures are taken to restore the environment and stop pollution, we will be unable to meet Pakistan’s water demands in the near future. It is estimated that a community of 10,000 people generate 40-acre inches of sewage effluent per day which is equivalent of 1 million gallons of wastewater. The prime objective of this presentation is to promote sustainable Liquid Waste Management Systems that support Green House Gas (GHG) emission reduction through The Clean Development Mechanism (CDM). Table 1: Sewage Capacity

# Numbers Effluent Energy1 1 person 100 gallons pd/ 1.46 acre inches pa2 25 persons 2,500 gallons pd 8 kWhrs pd3 Manure of 1 cow 3 kWhrs pd

It takes 2.4 kWhrs to light one 100 W bulb for 24 hrs.1.1 Definitions:1.1.1 Liquid Waste: Waste water from the community, including faecal matter, urine, household and commercial waste water that contains human waste but does not include stormwater.

i. Sewage/ Blackwater: Waste discharged from the human body into a toilet, and the water used for flushing the discharge.

ii. Sullage/ Greywater: Wastewater from a bath, basin, kitchen, laundry or shower.

iii. Liquid Trade Waste: All liquid waste other than sewage of a domestic nature.

iv. Hazardous Liquid Waste: Waste material that, when improperly handled, can cause substantial harm to human health and safety or to the environment. It is generated primarily by chemical production, manufacturing, and other industrial activities.

1.1.2 Biomelioration: Biological amelioration or using Biological means to improve or rectify existing harmful conditions.

1.1.3 Bioenvironmental Management: The attempt to minimize the impact on the environment of Natural Resource exploitation can be termed as Bioenvironmental Management.

1.1.4 Bioremediation: A more cost effective method of remediation as compared to incineration or physical and chemical remediation methods

1.1.5 Methanogenesis: Or Biomethanation is the formation of methane by microbes known as methanogens.

1.1.6 Bioaugmentation: The addition of non-toxic and non-pathogenic microorganisms, species of live bacteria suspended in a liquid medium that are non-offensive to humans, animals, plants and all types of aquaculture.

1.1.7 Phytoremediation: The use of plants to remove environmental pollutants from sites contaminated with inorganic and organic wastes. A form of ecological engineering that has proven effective as well as relatively inexpensive and holds great promise as a low-cost remedial approach.






1.1.8 Bio-Oxidation: The process of agitation or vertical drop of water to induce oxidation through aeration.

1.1.9 Composting: Process by which organic materials are biodegraded by microorganisms, resulting in the production of inorganic/organic byproducts and energy in the form of heat, carbon-dioxide and water.

1.2 The History of Methane:Table 2: History of Methane

10th Century BC Used to heat water in Assyria 16th Century Used to heat water in Persia17th Century Flammable gases found to be emitted from decaying organic

matter1776-1778 Methane discovered and isolated by Alessandro Volta.

Relationship between the amount of decaying organic matter and the amount of flammable gas produced demonstrated.

1808 Methane produced via controlled anaerobic digestion of cattle manure

1859 First digestion plant built in Bombay1895 Biogas recovered from a sewage treatment plant in England fueled

street lamps. The technology was developed in Exeter, where a septic tank was used to generate gas for the sewer destructor lamp, a type of gas lighting.

1904 The first dual-purpose tank for both sedimentation and sludge treatment was installed in Hampton, England. 1930s - Developments in microbiology identified the anaerobic bacteria and conditions needed to promote methane production

1970s Energy crisis renewed interest in AD1970s - 80s Lack of understanding and overconfidence resulted in numerous

failures China, India and Thailand reported 50% failure rates Failures of farm digesters in U.S. approached 80%

Figure 1Gas Street Lamp

1.3 Reasons for Failures:






Table 3: Reasons of Failure

1 Inadequate operator training.2 Management failures. 3 Benefits oversold.4 Operations too small to justify digester.5 High costs of Infrastructure.6 Excessive operating costs.7 Unreliable market for biogas.8 Impurity of Gas produced.9 Lack of appropriate microbial inoculation.10 Prevailing Contractor System.

1.5 What’s Different Now?Table 4: What's Different Now!

1 Improved designs and better understanding of O&M requirements.2 Cogeneration to raise volume of Methane captured. 3 High prices for liquid fuel & natural gas.4 Market evolving for biogas energy.5 Microbe culture in Laboratories.6 Methods of scrubbing gas produced along-with valuable by-products evolved.7 Possibility of deploying Multi-Use, Integrated Plant to address different problems

simultaneously. 8 Revolutionary; New; Low-cost; Low-Carbon; Super-Insulated; Disaster-Proof

Construction developed in Pakistan.9 System of CDM/ Carbon Credits created.

Figure 2 Geodesic DigestersAnaerobic Digester: Aerobic Digester:

1.5 Advantages & Disadvantages:






1.5.1 Advantages: Table 5:Advantages

# ITEM1 The odor potential of a well digested waste is considerably reduced. 2 Sanitary Aspects: The breeding of flies and mosquitoes is eliminated as the digestion

proceeds in the absence of oxygen.3 Efficient Use of Waste Material: Refuse, that is otherwise a problem to dispose, is put

to highly economic use.4 Anaerobic digestion reduces loss of nitrogen from 18.5 % to 1.0 % when compared to

the conventional handling of farmyard manure. Carbon loss is reduced from 33 % to 7.3 %. Phosphorus, potassium and calcium are not lost at all.

5 Digested waste has slightly less fertilizer value than non-digested waste, but it is more readily available to plants. It is simply converted to a more useful form.

6 If concentrated and compressed, it can also be used in vehicle transportation. Compressed biogas is becoming widely used in Sweden, Switzerland, and Germany. A biogas-powered train has been in service in Sweden since 2005. Biogas also powers automobiles, in 2007, an estimated 12,000 vehicles were being fueled with upgraded biogas worldwide, mostly in Europe.

1.5.2 Disadvantages. Table 6: Disadvantages

# ITEM1 A methane digester is large and expensive. The expense stems from the fact that it

must be well-insulated, air-tight and supplied a source of heat. The size of a conventional digester is equal to 15-20 times the daily waste volume produced, or more if the waste is diluted before digestion. The volume of waste that must be disposed of increases accordingly if dilution water is used.

2 A very high level of management is required. 3 A methane digester can be extremely sensitive to environmental changes, and a

biological upset may take months to correct. Methane generation ceases or is very low during an upset.

4 Start-up--usually the most critical phase of methane generation-is difficult. Methane-producing bacteria are very slow-growing, and several weeks are required to establish a large bacterial population.

5 Methane produced is mixed with corrosive gasses that increase wear and tear of machinery.

6 Methane is difficult to store, since at normal temperatures the gas can be compressed but not liquefied without special, very expensive equipment. Methane is extremely explosive when mixed with air at the proportions of 6-15 percent methane. Digester gas is heavier than air and settles to the ground, displacing oxygen. If hydrogen sulfide is present, the digester gas can be a deadly poison.

7 The decomposition of Liquid and Biodegradable Solid waste in the open releases two main gases that cause global climate change: nitrogen dioxide and methane. Nitrogen dioxide (NO2) warms the atmosphere 310 times more than carbon






dioxide and methane 21 times more than carbon dioxide Green House Gasses (GHG).

Figure 3 Green House GassesLandfill/ Sewer gas: Sewer gases may include hydrogen sulfide, ammonia,

methane, carbon dioxide, sulfur dioxide, and nitrogen oxides. Improper disposal of petroleum products such as gasoline and mineral spirits contribute to sewer gas hazards. Sewer gases are of concern due to their odor, health effects, and potential for creating fire or explosions.2. Liquid Waste:

Figure 4 Liquid WasteAquifer pollution is a main concern in Pakistan. The source is from both

municipal and industrial uses, with only about 1% of wastewater treated before disposal this has become one of the largest environmental problems in Pakistan.

The quality of surface water has also been identified as the major issue of water resources. Untreated waste discharged from factories, industrial units, residential areas and municipal waste are the prime culprits which are polluting sources of surface water. Industrial estates revealed some frightening figures that indicated serious threats to the aquatic, terrestrial, atmospheric ecosystems and to the well-being of human, plant and animal life. Sewage is allowed to mix with storm water as there is no separate sewage disposal. We must “Remember the drain is just for rain”.

Additionally the discharge of leachate from Open Air Dumping sites into nearby water bodies has caused water pollution concentrations exceeding standard values, for items such as NH3, Mn, and H2S. Analysis of well water found values above the






standards for Fecal Coliforms and Nitrates. With the exception of a few big cities, sewerage service is almost non-existent; where present it is used for peri-urban horticulture or merely dumped into nearby water bodies, causing serious public health problems. Nearly 45 % of all Pakistani households do not have access to a latrine. Furthermore, only 51 % of all households are connected to any form of drainage (35 % to open drain and 16 % to underground sewers or covered drains). Of particular reference to Pakistan are the two indicators related to provision of safe drinking water and sanitation coverage. They have direct linkages with health and therefore the productivity of the society and its future generations.

A high Biological Oxygen demand (BOD) indicates the presence of excess amounts of organic carbon. Oxygen depletion is a consequence of adding wastes with high BOD values to aquatic ecosystems. The higher the BOD of a source of waste, the higher it’s polluting power. BOD's of certain wastes are listed in the table below.

Table 7: Sewage Statistics

Type of Waste BOD(mg/L)Domestic Sewage 200-600Slaughterhouse Wastes 1,000-4,000Cattle Shed Effluents 20,000Vegetable Processing 200-5,000

Every year, millions of people, most of them children, die from diseases associated with inadequate water supply, sanitation and hygiene. Each and every day, some 6,000 children in developing and emerging countries die for want of clean water and sanitation. Water scarcity, poor water quality, and inadequate sanitation negatively impact food security, livelihood choices, and educational opportunities for poor families across the developing world. Yet, although far more people suffer the ill effects of poor water and sanitation services than are affected by headline-grabbing topics like war, terrorism, and weapons of mass destruction, those issues capture the public imagination – as well as public resources – in a way that water and sanitation issues do not. While agriculture is the key source of water pollutants in the developed world, human waste takes center stage in many developing countries, where 90 percent of sewage is dumped, untreated, into water systems. The net result is a serious reduction in both freshwater quantity and quality.

Even sewerage systems that “solve” environmental problems and avert health crises in one area often create environmental problems elsewhere by dumping the untreated sewage into another community’s water source or common property resource (such as lakes, rivers, coastal zone or the sea). The immediate trade-offs between improvements in human health and the quality of life in an urban area and serious negative environmental impacts on the surrounding area require careful consideration.

The three principal liquid waste sources within the scope of this presentation are:






Table 8: Liquid Waste Sources

# SOURCE1 Households.2 The Manufacturing Industry (Secondary Industry).3 Services Industry (Tertiary Industries).

Strict prevention of discharge of industrial effluent into natural streams is a serious issue to be addressed through incentives and punitive measures, coupled with cleaning of polluted water streams. A proper Sewerage System should have the following components:1

Figure 5 Sewerage Systems Components2.1 Households: Though the main liquid waste is sewage, households also generate some other volumes of liquid waste (both hazardous and non-hazardous). Hazardous waste liquids are generated when disposing of household chemicals. Most food waste is putrescible and will generate liquid as it decomposes. The key food groups disposed via the sink and sewer by households are:Table 9: Food Group Disposal via Sink/ Sewer

# Food Group

1 GOP






1 Soft Drinks.2 Dairy and eggs.3 Meal scraps.4 Condiments, sauces, herbs & spices.5 Staple foods.6 Meat and fish.7 Processed vegetables and salad.

2.2 Service Industries: Hospitals, laboratories and vehicle servicing generate hazardous industrial liquid wastes.2.3 Manufacturing Industry: All of the manufacturing industry generates sewage for example in the Leather Industry: One ton of salted rawhide will produce with 50 M3 of Liquid Effluent.Table 10: Leather Industry Effluent Analysis

# Analysis1 175 kgs of COD.2 60 kgs BOD.3 125 kgs of SS.4 6 kg of Chromium.5 510 kgs of solids (trimmings and flesh).

A significant portion of all Industry will also generate hazardous liquid wastes, the categories are as follows:Table 11: Industrial Hazardous Liquid Waste Categories

# Waste Categories1 Plating & heat treatment.2 Acids.3 Alkalis.4 Inorganic chemicals.5 Reactive chemicals.6 Paints, resins, inks, organic sludges.7 Organic solvents8 Pesticides9 Oils10 Putrescible/organic waste11 Industrial wash-water12 Organic chemicals13 Soil/sludge14 Clinical & pharmaceutical

2.3.1 Waste Stream or Wastes having as Constituents:Table 12: Industrial Waste Constituents

# Constituents






1 Acidic solutions or acids in solid form.2 Animal effluent and residues (abattoir effluent, poultry and fish processing waste).3 Antimony, antimony compounds.4 Arsenic, arsenic compounds.5 Asbestos.6 Barium compounds (excluding barium sulfate).7 Basic solutions or bases in solid form.8 Beryllium, beryllium compounds.9 Boron compounds.10 Cadmium, Cadmium compounds.11 Ceramic-based fibers with physico-chemical characteristics similar to those of

asbestos.12 Chlorates.13 Chromium compounds (hexavalent and trivalent).14 Clinical and related wastes.15 Cobalt compounds.16 Containers which are contaminated with residues of substances referred to in this

list.17 Copper compounds.18 Cyanides (inorganic).19 Cyanides (organic).20 Encapsulated, chemically-fixed, solidified or polymerized wastes.21 Ethers.22 Filter cake.23 Fire debris and fire wash-waters.24 Fly ash.25 Grease-trap waste.26 Halogenated organic solvents.27 Highly odorous organic chemicals (including mercaptans and acrylates).28 Inorganic fluorine compounds excluding calcium fluoride.29 Inorganic sulfides.30 Isocyanate compounds.31 Lead, lead compounds.32 Mercury, mercury compounds.33 Metal carbonyls.34 Nickel compounds.35 Non toxic salts.36 Organic phosphorus compounds.






37 Organic solvents excluding halogenated solvents.38 Organohalogen compounds - other than substances referred to in this list.39 Perchlorates.40 Phenols, phenol compounds including chlorophenols.41 Phosphorus compounds excluding mineral phosphates.42 Polychlorinated dibenzo-furan (any congener).43 Polychlorinated dibenzo-p-dioxin (any congener).44 Residues from industrial waste treatment/disposal operations.45 Selenium, selenium compounds.46 Sewage sludge and residues including night-soil and septic tank sludge.47 Soils contaminated with a controlled waste.48 Surface active agents (surfactants), containing principally organic constituents and

which may contain metals and inorganic materials.49 Tannery wastes (including leather dust, ash, sludges and flours).50 Tellurium, tellurium compounds.51 Thallium, thallium compounds.52 Triethylamine catalysts for setting foundry sands.53 Tires.54 Vanadium compounds.55 Waste chemical substances arising from research and development or teaching

activities including those which are not identified and/or are new and whose effects on human health and/or the environment are not known.

56 Waste containing peroxides other than hydrogen peroxide.57 Waste from heat treatment and tempering operations containing cyanides.58 Waste from the manufacture, formulation and use of wood-preserving chemicals.59 Waste from the production, formulation and use of biocides and phyto-

pharmaceuticals.60 Waste from the production, formulation and use of inks, dyes, pigments, paints,

lacquers and varnish.61 Waste from the production, formulation and use of organic solvents.62 Waste from the production, formulation and use of photographic chemicals and

processing materials.63 Waste from the production, formulation and use of resins, latex, plasticizers, glues

and adhesives.64 Waste from the production and preparation of pharmaceutical products.65 Waste mineral oils unfit for their original intended use.66 Waste oil/water, hydrocarbons/water mixtures or emulsions. 67 Waste pharmaceuticals, drugs and medicines.68 Waste resulting from surface treatment of metals and plastics.






69 Waste tarry residues arising from refining, distillation, and any pyrolytic treatment.70 Waste, substances and articles containing or contaminated with polychlorinated

biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polychlorinated terphenyls (PCTs) and/or polybrominated biphenyls (PBBs).

71 Waste of an explosive nature not subject to other legislation.72 Wool scouring waste.73 Zinc compounds.2.3.2 Other Hazardous Waste Streams: Some of the most persistent and harmful of all pollutants are those created by necessary Defense Production. Due to the sensitivity and need of such production, special attention needs to be paid to proper and safe disposal. Presently, this is not the case and such hazardous liquid waste is grossly polluting our water bodies.2.4 Hazardous Waste Management:

Hazardous waste is any waste material that, when improperly handled, can cause substantial harm to human health and safety or to the environment. Hazardous wastes can take the form of solids, liquids, sludge’s, or contained gases, and they are generated primarily by chemical production, manufacturing, and other industrial activities. They may cause damage during inadequate storage, transportation, treatment, or disposal operations. Improper waste storage or disposal frequently contaminates surface and groundwater supplies. People living in homes built near old and abandoned waste disposal sites may be in a particularly vulnerable position. In an effort to remedy existing problems and to prevent future harm from hazardous wastes, governments closely regulate the practice of hazardous-waste management.2.4.1 Hazardous Waste Characteristics:

Hazardous wastes are classified on the basis of their biological, chemical, and physical properties. These properties generate materials that are either, toxic, reactive, ignitable, corrosive, infectious, or radioactive. Toxic wastes are poisons, even in very small or trace amounts. They may have acute effects, causing death or violent illness, or they may have chronic effects, slowly causing irreparable harm. Some are carcinogenic, causing cancer after many years of exposure. Others are mutagenic, causing major biological changes in the offspring of exposed humans and wildlife. Reactive wastes are chemically unstable and react violently with air or water. They cause explosions or form toxic vapors. Ignitable wastes burn at relatively low temperatures and may cause an immediate fire hazard. Corrosive wastes include strong acidic or alkaline substances. They destroy solid material and living tissue upon contact, by chemical reaction. Infectious wastes include used bandages, hypodermic needles, and other materials from hospitals or biological research facilities. Radioactive wastes emit ionizing energy that can harm living organisms. Because some radioactive materials can persist in the environment for many thousands of years before fully decaying, there is much concern over the control of these wastes. However, the handling and disposal of radioactive material is not a responsibility of local municipal government. Owing to the scope and complexity of the problem, the management of radioactive waste (particularly nuclear fission waste) is usually considered to be a separate engineering task from other forms of hazardous-waste management and is discussed separately in nuclear






The primary constituents of waste streams from explosives manufacturing operations that result in liquid and soil contamination are nitroaromatics and nitramines including:Table 13: Explosives Waste Constituents

# Acronym Compound Name:1 TNT 2,4,6-trinitrotoluene.2 RDX Hexahydro-1,3,5-trinitro-1,3,5-triazine.3 HMX Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine.4 Tetryl Methyl-2,4,6-trinitrophenylnitramine.5 Picric Acid 2,4,6-trinitrophenol.6 PETN Pentaerythritol tetranitrate.7 TATB Triaminotrinitrobenzene.

The most frequently occurring impurities and degradation products from these include:Table 14: Explosives Waste Degradation Products

# Acronym Compound Name:1 2,4-DNT 2,4-dinitrotoluene.2 2,6-DNT 2,6-dinitrotoluene.3 2A-4,6-DNT 2-amino-4,6-dinitrotoluene.4 4A-2,6-DNT 4-amino-2,6-dinitrotoluene.5 TNB 1,3,5-trinitrobenzene.6 DNB 1,3-dinitrobenzene.7 NB Nitrobenzene.8 Picramic Acid 2-amino-4,6-dinitrophenol.

2.4.2 Bioaugmentation Treatment Materials:Table 15: Bioaugmentation Treatment Materials

Pharmaceuticals Spent Fermentation Media, Tabletzing Binders and Solvents

Refinery Wastes Phenols, ammonia, hydrogen sulfide, oils and greasesSteel Manufacturing Phenols, cyanide, thiocyanate, ammonia and rolling oilsTanneries Vegetable tanning wasteTextiles Surfactants, starches and organic dyes used in textile millsAlcohols Sugars, tannins and alcoholsBeverages Liquid sugars, high fructose corn syrup and flavoringsDairy Fats and wheyConfectionery Sugar waste and chemicalsHalogenated Aromatics Chloro and di-chloro phenolDetergent Surfactants and other components of detergentsPetrochemicals Petroleum hydrocarbons, straight and branched alkanes, BTXPaper/Cellulose BOD reduction and odor control






A study was carried out by myself in summer of 2005 for the Pakistan Ordnance Factories (POF) to present an Action Plan for remediation of hazardous effluent fro their Explosives Factory. It was realized that in order to arrive at a precise and dynamic Action Plan the following steps had to be undertaken.

3-Tier Approach.a) Preliminary Process Selection, Bio–Treatability Testing and Price Estimation.

a. Review all prior written studies, analysis and site work. Brief Review and Professional Appraisal carried out.b. Implement Bio-feasibility screening and Data Interpretation. Carried out.

b) Bio-treatability Studies and Process Confirmation.a. Laboratory Studies.b. In Situ, Ex Situ (water, slurry). Remedial Design/ Remedial Action

(RD/RA) for: In-Situ Pilot Scale Treatability Test Of Municipal Liquid/ Solid Waste.

Phase 1: Biodegradation of the Municipal Liquid Treatment Effluents (Aerobic, Anaerobic and Facultative).

Phase 2: Biodegradation of Municipal Solid Waste through Anaerobic Composting with Bioaugmentation.

a. In Situ, Ex Situ (water, slurry). Remedial Design/ Remedial Action (RD/RA) for: In-Situ Pilot Scale Treatability Test Of Hazardous Liquid/ Solid Waste.

Phase 3: Biodegradation of Hazardous Liquid Waste through Bio-oxidation and Phytoremediation.

Phase 4: Biodegradation of Hazardous Liquid Waste through Anaerobic Slurry Decomposition with Bioaugmentation.

Bioenvironmental Action Plan: Remedial Design/ Remedial Action (RD/RA) for: In-Situ Pilot Scale Treatability Test of Liquid/ Solid Waste Bio/ Phytoremediation of:1: Mixture of Mono, Di and Tri-Nitro Toulene, Tetryl and Nitrocellulose, Hazardous

Liquid Waste.2: Municipal Liquid Waste.3: Hazardous Solid Waste.4: Municipal Solid Waste.

Table 16:Proposed Bioremediation Process

Phase ITEMPhase 1 Biodegradation of Municipal Liquid WastePhase 2 Biodegradation of Municipal Solid WastePhase 3 Bio-oxidation of Hazardous Liquid WastePhase 4 Phytoremediation of Hazardous Liquid WastePhase 5 Anaerobic Biodegradation of Hazardous Liquid Waste






Biological treatment or bioremediation is a developing technology that uses microorganisms to degrade organic contaminants into less harmful compounds. Phytoremediation uses plants to degrade and uptake organic and inorganic contaminants. They are practical and inexpensive alternatives to traditional methods such as incineration, which often produce toxic secondary wastes or simply lowering of pH. The sites this report addresses are potential sites for these types of bio/ phytoremediation.

Our goal was to treat the Municipal Liquid Waste site is to use bioremediation as the primary treatment and anaerobic slurry decomposition as secondary treatment. Municipal biodegradable Solid Waste was to be composted anaerobically along with bioaugmentation. For the Hazardous Liquid Waste bio-oxidation as primary and Phytoremediation or anaerobic slurry decomposition as secondary treatments was proposed. Our aim was to reduce the hazardous properties of the target compounds through the process of bio and phytotransformation and offer as near complete return of the compounds into the normal geochemical carbon and nitrogen cycles through mineralization.Sites Evaluation

Two Liquid and one Solid Waste Dump Sites were visited by the Bioenvironmental Management Consultant.

Solid Waste Dumping Ground consisted of Open Air Dumping of untreated and non-segregated Solid Waste. As facilities for secondary segregation do not exist and are expensive to install, the Consultant recommended Primary Segregation (Segregation on the part of the polluting agency into Biodegradable and Non Degradable Streams. The Biodegradable Waste can then be effectively anaerobically composted, using Bioaugmentation. This method is extremely effective and rapid apart from being low-cost. For Demonstration purposes as near primarily segregated biodegradable municipal solid waste was to be anaerobically composted along with bioaugmentation.

Municipal Liquid Waste Treatment Plant with inflow of 4 times the rated capacity (50,000 population) has resulted in incomplete digestion and discontinuation of anaerobic decomposition in the facility that exists from over 100 years. It is possible to increase the efficiency of decomposition and thus make maximum use of existing facilities. This would entail bioaugmentation with a range of products to determine efficacy and adaptation to local conditions. On successful treatment the products can be cultured locally either independently or as Joint Venture with the manufacturer. Similarly, the anaerobic digester can be re-commissioned (subject to structural soundness).

Hazardous Liquid Waste Treatment is restricted to open air incineration, oxidation and regulation of pH to neutral value. At the exit point a combination of Hydraulic Ram for raising the Liquid Waste in order to access near by Bank of Dhamrah Kas for purposes of Phytoremediation trials will be required. As capacity of adjoining area and rate of production of Liquid waste (4 cusecs) both do not match and also due to the requirement for demonstration for efficacy, a limited quantity of Liquid Waste was to be introduced to the Beds. Remainder effluent will rejoin its original watercourse after biooxidation/ deionization through the means of a created waterfall. This process will be replicated at the point where effluent subjected to phytoremediation rejoins the Dhamrah Kas.






Along with these treatments, it was proposed to pipe a part of the effluent to the anaerobic digester situated in the Municipal Liquid waste Treatment Plant. This would serve to show anaerobic decomposition as a demonstration for evaluation purposes.Thus the Sites would be subjected to the following:Bioaugmentation:Phytoremediation:Bio-Oxidation:Anaerobic Bioslurry/ Composting:Site 1: Bioaugmentation: Municipal Treatment Plan:

Anaerobic Digester:

Figure 6 Treatment PerspectiveSite 2: Composting: Anaerobic Bioaugmentation: Hazardous Liquid Waste Pre-Treatment Plant:Phase D: Anaerobic Decomposition of Hazardous Waste:Site 3:Phase A: Hydraulic Ram.Phase B: Waterfall Oxidation/ Deionization.Phase C: “Red Beds”.Site 4: Waterfall Oxidation/ Deionization.Table 17: Compounds Proposed for Degradation

# Compounds to be Degraded:1 Mono, Di and Tri-Nitro Toluene2 Nitrocellulose (cellulose nitrate) 3 Tetryl






4 Sulfate5 Oil & Grease6 Sulphide7 Chlorine8 Chloride9 Lead10 Iron11 Cadmium12 Chromium13 Nitrocellulose (cellulose nitrate)

Phase 1. Biodegradation of the Municipal Liquid Treatment Effluents (Aerobic, Anaerobic and Facultative).Phase 2. Biodegradation of Municipal Solid Waste through Anaerobic Composting with Bioaugmentation.Phase 3. Biodegradation of Hazardous Liquid Waste through Bio-oxidation and Phytoremediation.Phase 4. Biodegradation of Hazardous Liquid Waste through Anaerobic Slurry Decomposition with Bioaugmentation.

Application and Sampling Methods: Initially, sampling the site will involve samples from monitoring points placed

around the site. Sampling should be conducted to determine contaminant levels as well as nutrient levels in the effluents. Sampling of the water would also be important. Information on the nutrient levels is important so that possible growth rates can be established.

Foreseeable Problems: The problems that can occur during the bioremediation of these explosive

compounds could arise from the bacteria and fungi unable to adapt to the extreme anaerobic or anaerobic environment for example the anaerobic fungi isolated from the rumen might not tolerate the conditions given. Due to the assumption made, that this fungi will be able to degrade nitrocellulose in an ideal laboratories conditions may not necessary mimic the activities in the environment. Other microorganisms, like the de-nitrifiers which grow relatively fast, might use up the entire available nitrate and inhibit their own growth. Furthermore, the assumption that the ammonium ions and nitrate ions are in equilibrium might not hold due to an influx of microbial activities, which might inhibit denitrification. This inhibition of denitrification may occur due to temperature increase in the summer, nutrient levels too low or too abundant.

Problems that might occur during biodegradation, or might already be occurring include the release of nitric oxide, nitrous oxide and nitrogen dioxide into the environment. This needs to be monitored, as both nitrogen dioxide and nitric oxide are toxic to humans and to many other organisms. Nitrous oxide is able to diffuse up to the lower atmosphere and up to the stratosphere where it reacts with the ozone causing partial






damage to the protective layer (Boyd, 1988). UV penetration to the surface of the earth is further increased.Costs:

The need for prevention of environmental contamination from hazardous wastes is overwhelming. The cost for remediation of these contamination sites all over Pakistan is estimated at over 10 Arab Rupees, and even at this cost most sites would not be achieve 'pristine' condition. Most technologies currently considered for remediation are expensive and often do not effectively alleviate the pollution hazard. Bio/ Phytoremediation is usually much cheaper than other clean-up options, and provides great adaptability and tailorabilty to specific environments (Walker and Kaplan, 1992).

3. Health Issues:4.3.1 Major Excreta Related Diseases:

Table 18: Major Excreta Related Diseases

Category Disease Transmission MechanismFecal Oral(Non Bacterial)

Hepatitis A Amoebic

Dysentery Rotavirus Giardiasis

Person to Person Contact Domestic Contamination

Fecal Oral(Bacterial)

Cholera Salmonellosis Shigellosis Many forms of

Diarrhea

Person to Person Contact Domestic Contamination Water Contamination Crop Contamination

Soil Transmitted Helminths Hookworm Roundworm Whipworm

Compound Contamination Communal Defecation Areas Crop Contamination

Tapeworms Beef Tapeworm Port Tapeworm

Compound Contamination Field Contamination Fodder Contamination

Water-Based Helminths Schistosomisis Water ContaminationExcreta Related Insect Vectors

Filariasis Some Fecal Oral

Diseases

Insects Breeding/ Feeding in Poor Sanitation Sites

3.2 Excreta Related Diseases and their Characteristics:

Table 19: Excreta Related Diseases & CharacteristicsDisease Specific

AgentReservoir Transmission Incubation

PeriodHookworm(Anctlostomiasis)

Necator americanusAncylostoma

Man Fecal contamination of the soil; eggs hatch, infective larvae penetrates the bare skin, usually of the foot.

Few weeks to several months






duodonaleAncylostoma ceylanicum

Ascariasis (Roundworm)

Ascarsis Lumbricoids

Man Ingestion of infective eggs from contaminated soils, salads and other foods eaten raw, eating with contaminated hand.

Two months

Tapeworm Taenia saginata Man Ingestion of raw or partially cooked meat containing infected larvae passed through feces.

8 to 14 weeks

Entrobiasis(Pinworm, Thread worm)

Entrobius vermicularies

Man Direct transfer of infected eggs by hand from anus to the mouth; indirect through contaminated fomites.

3 to 6 weeks

Poliomyelitis Poliovirus type 1,2,3

Man Direct contact with pharyngeal secretion or feces of infected person.

Commonly 7 to 12 days range from 3 to 21 days

Bilharziasis Schistosoma haematobiumSchistosoma mansoni

Man Exposure to infected water during bathing or wading.

Months

Strongyloidiasis Strongyloids stericolaris

Man, possibly dogs

Infected soils in moist soil contaminated with feces penetrates the skin usually of the foot

17 days

Viral Diarrhea Ratavirus Probably Man Probably fecal-Oral and possibly Fecal-Respiratory

Approximately 48 hours

Infectious Hepatitis A

Hepatitis A virus

Man Person to Person by the Fecal-Oral route From 15 – 50 days depending on dose

Cholera Vibrio Cholerae Man Ingestion of water contaminated with feces or vomitus of patients, ingestion of food contaminated with dirty hand, fomites etc.

From a few hours to five days

Shigellosis(Bacillary Dysentery)

Shigella bacteria species

Man Direct or indirect Fecal-Oral transmission from patient or carrier

One to seven days, usually one to three days

Typhoid and Paratyphoid

Salmonella typhi

Man both patients and especially carriers

By food or water contaminated by feces or urine of a patient or carrier; fruits; vegetables harvested from sewage contaminated area.

Usually ranges from 1-3 weeks depending on dose

Giardiaa lambliasis Giardia laambia Man, possibly other wild or domestic animals

Ingestion of cysts in feacally contaminated water or less often faecally contaminated food

5-25 days or longer, median is 7-10 days

Amoebiasis Entmobeba Histolitica

Man Epidemic outbreaks result mainly from ingestion of faecally contaminated water containing amoebic cysts. Endemic spread involves hand to mouth transfer of feces from contaminated raw vegetables, by flies or soiled hands of food vendors

From a few days to several months or years. Commonly 2-4 weeks

Tricuriasis Tricuruis Tricuria

Man Ingestion of developed eggs, which have been deposited with feces on to the ground

Indefinite

3.3 Survival Time of pathogens in days by different Disposal or Treatment Conditions.

Table 20:Pathogen Survival Times by Disposal/ TreatmentConditions Bacteria Viruses Protozoa Helminthes

(Ascaris)Soil 400 175 10 Many monthsCrops 50 60 Not known Not knownNight Soil, feces, sludge 20-30° C 90 100 0 Many monthsComposting (anaerobic at ambient temperature) 60 60 30 Many months






Thermophilic Composting (50-60° C maintained for 7 days)

7 7 7 7

Waste Stabilization Ponds (Retention Time greater than 20 days)

20 20 20 20

5. Managing the Use of Water:

5.1 BACT: Best Available Control Technology (BACT) is based on optimum capacity to promote pollution prevention using the 3Rs and Resource, Recovery and Residuals Management e.g. for sewage discharges, pollution prevention using the 3Rs means to:

Table 21: Best Available Control Technology (BACT) 3Rs

# Results1 Reduce the toxic contaminants discharging to sewers and ultimately in the effluent;2 Reuse the municipal sludge beneficially as a soil conditioner, fertilizer or for making

top soil; and3 Recycle the effluent economically as irrigation or industrial process water.

Secondary sewage treatment best meets these goals and will satisfy the toxicity prevention requirements of Environment Protection. Secondary Treatment enables nutrients and water to be economically recovered and residuals to be beneficially managed. Tertiary treatment can be readily applied to reduce specific contaminants when necessary. Secondary sludge and effluent can be routinely tested for toxicity and metals, and provide a good monitor on toxic discharges to the sewer and the effectiveness of source control programs. BACT for sewage discharges has therefore been determined to be secondary treatment. 5.2 The Sustainable Region Initiative (SRI2): This idea is derived from Canadian Good Governance in Metro Vancouver and has its framework for decision making as well as the mechanism by which sustainability imperatives are moved from ideas into action. The SRI has been driven by three overarching principles which state that decision making must cater for:Table 22: Overarching Principles

# Principles1 Have regard for both local and global consequences, and long term impacts;2 Recognize and reflect the interconnectedness and interdependence of systems; 3 Be collaborative.

These provide the foundation for the three sets of sustainability principles.

2 Metro Vancouver, Canada.






Table 23: Sustainability Principles

# Sustainability Principles1 Protect and enhance the natural environment (conserve and develop natural capital);2 Provide for ongoing prosperity (conserve and develop economic capital); 3 Build community capacity and social cohesion (conserve and develop social capital).

The long-term vision for liquid waste management is that all elements of liquid waste will be efficiently recovered as energy, nutrients, water or other usable material or else returned to the environment as part of the hydrological cycle in a way that protects public health and the environment.

This vision and the Sustainable Region Initiative are supported by three goals:

Goal 1: Protect Public Health and the Environment:Public health and the environment are protected by managing sanitary sewage and

stormwater at their sources, and providing wastewater collection and treatment services protective of the environment.Goal 2: Use Liquid Waste as a Resource:

Energy will be recovered from the heat in the sewage and from biogas generated in the treatment process. Materials which have nutrient value will be recovered from wastewater treatment plants. Water will be recovered from the wastewater treatment process and stormwater will be kept separate from effluent.Goal 3: Effective, Affordable and Collaborative Management:

Monitoring, maintaining and investing in liquid waste infrastructure are essential to ensuring effective system performance and preventing costlier repairs. Innovative alternative approaches to traditional treatment systems will be explored. Opportunities for positive synergies with other utilities and regional management systems will be pursued—such as integrated stormwater management plans. Sources of risk will be identified and mitigated.

4.2.2 Integrated Resource Recovery: A concept and approach that integrates the management of water, wastewater, energy and solid waste services to recover resources and value and to help increase resiliency. IRR planning and resource recovery actions in this plan support the Climate Action Plan, the Energy Plan, and Living Water Smart. The Energy Plan: A Vision for Clean Energy Leadership: In support of the Provincial Government’s vision for “clean energy leadership” and electricity self-sufficiency by 2016, this plan seeks to expand the production of biogas from wastewater, and to recover heat energy from wastewater for use in district heating systems. The IRR approach to integrating liquid and solid waste management will also support the Bio-Energy Strategy: Growing Our Natural Energy Advantage. In partnership with Municipalities and the Private Sector, initiatives in these areas will reduce greenhouse gas emissions, diversify the region’s sources of energy, provide renewable energy and increase our energy independence. Water Smart objectives supported by this plan include the requirements to complete and implement municipal Integrated Stormwater Management Plans, support rainwater harvesting and water reclamation actions, the development of an understanding






of what makes streams healthy, watershed management planning in priority areas, and helping address the impacts of climate change and climatic variability on local water resources. This will be supported by the ongoing work of a new overarching integrated utility management advisory committee.

4.2.2 Use Liquid waste as a Resource:The goal of using liquid waste as a resource marks two important advances in the

thinking about liquid waste in the context of Metro Vancouver’s sustainability framework.

The first is the recognition that the traditional and still vitally important functions of liquid waste management to protect public health and the environment will ultimately be achieved most beneficially by converting liquid waste into usable resources. Liquid waste is a source of green energy and nutrients and, in addition to stormwater; it can provide alternative sources of water. Strategies are included in this plan to address these opportunities.

The second, which follows logically from the first, is the recognition that the opportunities for cost effective resource recovery from liquid waste are magnified when explored in the context of integrated resource recovery from the whole range of urban management systems. This is essentially the implementation of the second ‘overarching imperative’ of the SRI framework: “Recognize and reflect the interconnectedness and interdependence of systems”.

A major challenge for Metro Vancouver and its members will be to adapt the legacy sewerage and stormwater infrastructure of the 20th century to a more sustainable, integrated 21st century system focused on integrated resource recovery. This will involve embracing new technologies and reshaping communities and their infrastructure so that the resources and energy recovered can be used efficiently and effectively: integrating a new kind of liquid waste infrastructure with building design, community and nature. This involves managing liquid wastes as a resource, minimizing discharges, minimizing financial risks, and maximizing the quality of discharges.






Figure 7 Sustainable Resource Initiative

4.3 Water Treatment Projects Design Philosophy for Developing Countries: What type of technology is?






Table 24: Design Philosophy Indicators

# Indicators1 Acceptable?2 Sustainable?3 Easily operable?4 Replicable?5 Replaceable or maintainable?6 Beneficial / not a liability?

These are some of the questions that must be clearly answered in order to have viable and sustainable community based sanitation. In many cities, towns and rural areas of Pakistan today people live and raise their children in highly polluted environment. Urban and peri-urban areas are among the worst polluted and disease ridden habitats. Much of this pollution, which leads to high rates of disease, malnutrition and death, is caused by lack of adequate excreta disposal facilities and inadequate solid waste collection and disposal service. As communities expand and population increase, the situation will grow worse and the need for safe, sustainable and affordable sanitation technology or system will be even more critical.

Secondly, the technology must:Table 25: Technology Imperatives

# Technology Imperatives1 Produce reliable Treatment.2 Ensure easy Plant Operation and maintenance.3 Minimize Imported items.4 Reduce Mechanization and Instrumentation.5 Maximize local labor during construction and operation.6 Limit Energy demands.7 Use local materials whenever possible.8 Provide adequate flexibility.

For Water Treatment Projects to produce high quality water several conditions must be met:Table 26: Conditions for High Quality Water Production

#1 Staff must understand the process and equipment.2 Mechanical and electrical equipment must be durable.3 Spare parts and the availability of local repair and maintenance must exist.4 Process units that will perform under varying water qualities and forgive occasional

oversight of operations personnel must be purchased.5 Reliable suppliers of equipment with dependable local agents must be available.5. Biological Treatment: Biological treatment is the most economical of waste treatments available today. In biological systems, the dynamics are biochemical as opposed to chemical, and the active agents are living entities. In chemical treatment we have to increase the quantity of chemical






proportionally to deal with a higher load of reactant, in a biological system the biological additive can grow to help compensate for increased loadings. The septic system is a biological process. Like any living thing, it has certain nutritional requirements to function properly and functions best in a suitable environment. However, the best first step in optimizing the performance of a septic system is to have a complete ecosystem of the organisms required for the most complete breakdown of the waste.

Bacteria are typically 1-2 um wide and 2-20 um long. Due to the small size, shape or morphology they can be examined only by using a high power microscope (x1000) and staining techniques. The Gram Stain is the basic criteria used to categorize the groups of bacteria as either gram positive or gram negative, indicating a fundamental variation in cell-wall structure.

Use of oxygen in degrading organic matter o uses oxygen only -- aerobic; o can metabolize with or without oxygen -- facultative; o does not use oxygen – anaerobic.

Use of carbon sources organic -- heterotrophic; carbon dioxide -- autotrophic Optimum growth at different temperatures

o Thermophiles -- 55-75° C o Mesophiles -- 30-45° C o Psychrophiles:

Obligate -- 15-18° C Facultative -- 25-30°C

Aerobic wastewater treatment systems operate in the temperature range of 10-40° C and therefore contain mainly mesophilic bacteria. These include both the gram positive types, such as Bacillius, and the gram negative types, such as Pseudomonas Successful bioaugmentation requires total system management If the microbiological population can be viewed as a workforce, then the consultant or system manager is responsible for keeping the workforce productive.

If liquid wastes are discharged into rivers, ponds, lands, etc., without proper treatment, the result is offensive odor and pollution of water and air as they will emit gases like methane and Carbon Dioxide. By adopting environmental friendly technologies, these problems can be mitigated. These waste waters can be treated using numerous processes depending on the type and extent of contamination. A typical wastewater treatment plant includes physical, chemical and biological treatment processes.

Methane is generated in landfills as waste decomposes and in the treatment of wastewater.

Sewer gas is a complex mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may include hydrogen sulfide, ammonia, methane, carbon dioxide, sulfur dioxide, and nitrogen oxides. Improper disposal of petroleum products such as gasoline and mineral spirits contribute to sewer gas hazards. Sewer gases are of concern due to their odor, health effects, and potential for creating fire or explosions.






Anaerobic digesters were originally designed for operation using sewage sludge and manures. Sewage and manure are not; however, the material with the most potential for anaerobic digestion, as the biodegradable material has already had much of the energy content taken out by the animals that produced it. Therefore, many digesters operate with co-digestion of two or more types of feedstock which can increase energy output tenfold for only three times the capital cost, relative to a slurry-only system.5.5 Wastewater Treatment Plants:

Wastewater treatment facilities employ anaerobic digesters to break down sewage sludge and eliminate pathogens in wastewater. Often, biogas is captured from digesters and used to heat nearby facilities. Some municipalities have even begun to divert food waste from landfills to WWTPs; this relieves waste burdens placed on local landfills and allows for energy production It is estimated that 544 large WWTPs (those that process more than five million gallons of wastewater per day) currently utilize anaerobic digesters to produce biogas. A WWTP digester that also processes food waste will have a payback period of around 6 months to 3 years Modern method of treating industrial waste water is by installing advanced anaerobic digestion plants. Modern high rate reactors can reduce the COD of the waste water by 85-95%.

Figure 8 Wastewater Treatment Stages5.2 Methane:

Methane is the simplest alkane and a major component of natural gas, about 87% by volume. The major source of methane is extraction from geological deposits known as natural gas fields. Methane is a chemical compound with the chemical formula CH4. It is probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel. Methane is a relatively potent greenhouse gas. The concentration of methane in the Earth's atmosphere in 1998, expressed as a mole fraction, was 1,745 nmol/mol (parts per billion, ppb), up from 700 nmol/mol in 1750. By 2008, however, global methane levels, which had stayed mostly flat since 1998, had risen to 1,800 nmol/mol. Methane is a tetrahedral molecule with four equivalent C-H bonds, its electronic structure is described by four bonding molecular orbitals (MOs) At room temperature and standard pressure, methane is a colorless and odorless gas. The familiar smell of natural gas as used in homes is a safety measure achieved by the addition of an odorant. Methane has a boiling point of −161 °C (−257.8 °F) at a pressure of one atmosphere. As a gas it is flammable only over a narrow range of concentrations (5–15%) in air. Like other hydrocarbons, methane is a very weak acid. In the combustion of methane, multiple steps are involved. The following equations are part of the process, with the net result being:5.2.1 CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −891 kJ/mol (at standard conditions))Table 27:Methane Combustion Process Equations

# Equation






1 CH4+ M* → CH3 + H + M2 CH4 + O2 → CH3 + HO2

3 CH4 + HO2 → CH3 + 2 OH4 CH4 + OH → CH3 + H2O5 O2 + H → O + OH6 CH4 + O → CH3 + OH7 CH3 + O2 → CH2O + OH8 CH2O + O → CHO + OH9 CH2O + OH → CHO + H2O10 CH2O + H → CHO + H2

11 CHO + O → CO + OH12 CHO + OH → CO + H2O13 CHO + H → CO + H2

14 H2 + O → H + OH15 H2 + OH → H + H2O16 CO + OH → CO2 + H17 H + OH + M → H2O + M*

18 H + H + M → H2 + M*

19 H + O2 + M → HO2 + M*

The species M* signifies an energetic third body, from which energy is transferred during a molecular collision.

Methane in the Earth's atmosphere is a significant greenhouse gas with a global warming potential of 25 compared to CO2 over a 100-year period (although accepted figures probably represent an underestimate). This means that a methane emission will have 25 times the effect on temperature of a carbon dioxide emission of the same mass over the following 100 years. Methane has a large effect for a brief period (a net lifetime of 8.4 years in the atmosphere), whereas carbon dioxide has a small effect for a long period (over 100 years). Because of this difference in effect and time period, the global warming potential of methane over a 20 year time period is 72. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases (these gases don't include water vapor which is by far the largest component of the greenhouse effect). Usually, excess methane from landfills and other natural producers of methane is burned so CO2 is released into the atmosphere instead of methane, because methane is a more effective greenhouse gas. Recently, methane emitted from coal mines has been successfully utilized to generate electricity.

Globally, over 60% of total CH4 emissions come from human activities. Methane is emitted from industry, agriculture, and waste management activities globally; the Agriculture sector is the primary source of CH4 emissions.

5.3 Methanogenesis:






Also known as biomethanation is the formation of methane by microbes known as methanogens. Organisms capable of producing methane have been identified from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although many live in close association with anaerobic bacteria. The production of methane is an important and widespread form of microbial metabolism. In most environments, it is the final step in the decomposition of biomass.

Methanogenesis in microbes is a form of anaerobic respiration. Methanogens do not use oxygen to respire; in fact, oxygen inhibits the growth of methanogens. Methanogenesis is the final step in the decay of organic matter. During the decay process, electron acceptors (such as oxygen, ferric iron, sulfate, and nitrate) become depleted, while hydrogen (H2) and carbon dioxide accumulate. Light organics produced by fermentation also accumulate. During advanced stages of organic decay, all electron acceptors become depleted except carbon dioxide. Carbon dioxide is a product of most catabolic processes, so it is not depleted like other potential electron acceptors.

Only methanogenesis and fermentation can occur in the absence of electron acceptors other than carbon. Fermentation only allows the breakdown of larger organic compounds, and produces small organic compounds. Methanogenesis effectively removes the semi-final products of decay: hydrogen, small organics, and carbon dioxide. Without methanogenesis, a great deal of carbon (in the form of fermentation products) would accumulate in anaerobic environments.

Strains of Methanogens:

Methanobacterium bryantii. Methanobacterium formicum. Methanobrevibacter arboriphilicus. Methanobrevibacter gottschalkii. Methanobrevibacter ruminantium. Methanobrevibacter smithii. Methanocalculus chunghsingensis. Methanococcoides burtonii. Methanococcus aeolicus. Methanococcus deltae. Methanococcus jannaschii. Methanococcus maripaludis. Methanococcus vannielii. Methanocorpusculum labreanum. Methanoculleus bourgensis (Methanogenium olentangyi &

Methanogenium bourgense). Methanoculleus marisnigri. Methanofollis liminatans. Methanogenium cariaci. Methanogenium frigidum. Methanogenium organophilum. Methanogenium wolfei. Methanomicrobium mobile.






Methanopyrus kandleri. Methanoregula boonei. Methanosaeta concilii. Methanosaeta thermophila. Methanosarcina acetivorans. Methanosarcina barkeri. Methanosarcina mazei. Methanosphaera stadtmanae. Methanospirillium hungatei. Methanothermobacter defluvii (Methanobacterium defluvii). Methanothermobacter thermautotrophicus (Methanobacterium

thermoautotrophicum). Methanothermobacter thermoflexus (Methanobacterium thermoflexum). Methanothermobacter wolfei (Methanobacterium wolfei). Methanothrix sochngenii.

Different organisms are able to survive at different temperature ranges. Ones living optimally at temperatures between 35 and 40 °C are called mesophiles or mesophilic bacteria. Some organisms can survive at the hotter and more hostile conditions of 55 to 60 °C; these are called thermophiles or thermophilic bacteria. Methanogens come from the domain of archaea. This family includes species that can grow in the hostile conditions of hydrothermal vents, so are more resistant to heat, and can, therefore, operate at high temperatures, a property unique to thermophiles.

5.4 Thermophillic Digesters:Thermophillic (high-temperature) digesters have been designed that operate

satisfactorily at a 5-day detention time and a solids level of 10-20 percent. Digester gas production has been around 11 cubic feet per pound of volatile solids destroyed. Operation is normally started by bringing the digester up to a temperature of 130F at a rate of about 3F per week.

In many ways, thermophillic digestion is better than digestion at 95 degrees F. Gas production is about 20 percent higher and solids breakdown about 10 percent higher. In addition, the higher temperature kills more pathogenic bacteria, thus allowing the digested waste to be used as a feed supplement without further sterilization.

But thermophillic bacteria digestion also has its disadvantages. The methane content of the gas is somewhat lower (55 percent), and digester operation is not quite as stable as conventional digesters.

5.5 Energy: Methane is important for electrical generation by burning it as a fuel in a gas turbine or steam boiler. Compared to other hydrocarbon fuels, burning methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion is lower than any other hydrocarbon but the ratio of the heat of combustion (891 kJ/mol) to the molecular mass (16.0 g/mol, of which 12.0 g/mol is carbon) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit (55.7 kJ/g) than other complex hydrocarbons. In many cities, methane is piped into homes for domestic heating and cooking purposes. In this context it is usually known






as natural gas, which is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot.

The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a fuel in any country for any heating purpose, such as cooking. It can also be used in anaerobic digesters where it is typically used in a gas engine to convert the energy in the gas into electricity and heat. Biogas can be compressed, much like natural gas, and used to power motor vehicles. In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. Biogas is a renewable fuel so it qualifies for renewable energy subsidies in some parts of the world. Biogas can also be cleaned and upgraded to natural gas standards when it becomes bio methane.

By 2010, there was 35GW of globally installed bioenergy capacity for electricity generation, of which 7GW was in the United States. A 2 cubic meter bio-digester can produce 2 cubic meter of cooking gas. This is equivalent to 1 kg of LPG.

United Nations Development Program as one of the most useful decentralized sources of energy supply, as they are less capital-intensive than large power plants. With increased focus on climate change mitigation, the re-use of waste as a resource and new technological approaches which have lowered capital costs, anaerobic digestion has in recent years received increased attention among governments in a number of countries

If localized anaerobic digestion facilities are embedded within an electrical distribution network, they can help reduce the electrical losses associated with transporting electricity over a national grid. Biogas from sewage works can be used to run a gas engine to produce electrical power, some or all of which can be used to run the sewage works. Some waste heat from the engine is then used to heat the digester. The waste heat is, in general, enough to heat the digester to the required temperatures. The power potential from sewage works is limited The scope for biogas generation from non-sewage waste biological matter – energy crops, food waste, abattoir waste, etc. - is much higher, estimated to be capable of about 3,000 MW. Food waste is currently co-digested with primary and secondary municipal wastewater solids and other high-strength wastes. Compared to municipal wastewater solids digestion alone, food waste co-digestion has many benefits. Anaerobic digestion of food waste pulp provides a higher normalized energy benefit, compared to municipal wastewater solids: 730 to 1,300 kWh per dry ton of food waste applied compared to 560 to 940 kWh per dry ton of municipal wastewater solids applied. If manure from “Gawala” Colonies is added to the digester for co-generation a manifold increase of benefits can be achieved, for instance one cow can produce enough manure in one day to generate three kilowatt hours of electricity; only 2.4 kilowatt hours of electricity are needed to power a single one hundred watt light bulb for one day.

Engine efficiency can be improved by removing carbon dioxide from the digester gas before combustion, then burning the remaining methane. Digester gas can also be injected into the air stream in a stationary diesel engine. Up to 90 percent of the fuel entering an engine by this technique can be methane gas.

5.5.1 Use & Consumption of Biogas:

Table 28: Use & Consumption of Biogas






Use Units of consumption of gas

For cooking purposes (per person per day)

12 to 15 cft

To operate gas lamps 2j cft per mantle per hourTo operate gas engines Ib cft per BHP per hourTo operate electricity 22 cft gas 1 Unit equivalent to 1 kWh of electricity

In place of petrol 225 cft gas 1 gallon equivalent to petrolIn place of diesel oil 250 cft gas 1 gallon equivalent to of diesel oil

Methane production is usually expressed in terms of cubic feet of gas generated per pound of volatile solids destroyed. Volatile solids are the organic portion of livestock waste; about 80 percent of the manure solids are volatile. A gallon of liquid manure containing 8 percent solids potentially can provide about 3 3/4 cubic feet of digester gas, or 2 1/2 cubic feet of methane (Roughly 10-13 cubic feet of gas can be produced per pound of volatile solids destroyed in a properly-operating digester. Since about half of the volatile solids added can be destroyed and half to three-fourths of the gas produced will be methane, about 5 cubic feet of digester gas (3 cubic feet of methane) can be produced per pound of total manure solids added. In terms of digester size, it is possible to produce 3/4 to 2 1/2 cubic feet of gas (1/2 to 1 1/2 cubic feet of methane) per cubic foot of digester volume. The gas production expected from various livestock species is shown below:

5.5.1 Daily Waste and Methane Production by Dairy, Beef per 1,000 Pounds of Animal Weight.

Table 29: Dry Manure Methane Production

Item Dairy BeefRaw manure (lb.) 82.0 60.0 Total solids (lb.) 10.4 6.9 Volatile solids (lb.) 8.6 5.9 Methane potential (cu.ft.)* 28.4 19.4

* Based on 65 percent of gas being methane

5.5.2 Waste Methane Contents and Petrol Equivalents:Table 30: Waste Methane Contents & Petrol Equivalents

Item Methane per Ton Dry Waste

Tons of Petrol Equivalents per Ton of Dry Waste

Food waste 500 0.43






Paper 330 0.28Grass 310 0.26Branches and leaves

110 0.09

Start-up can be speeded by providing a source of methane bacteria. One way of doing this is to initially fill 20-25 percent of the digester volume with active waste digester sludge from a municipal sewage plant, then to gradually increase the amount of livestock waste added at each loading over a 6-8 week period until the system is fully operational. Another, perhaps more effective method, is the production of methane bacteria in laboratories.5.5.3 Developing Technologies:

Research is being conducted by NASA on methane's potential as a rocket fuel. One advantage of methane is that it is abundant in many parts of the solar system and it could potentially be harvested on the surface of another solar-system body, providing fuel for a return journey. The assembly of a 5,500-pound-thrust liquid oxygen/liquid methane rocket engine has been completed. Current methane engines in development produce a thrust of 7,500 pounds-force (33 kN), which is far from the 7,000,000 lbf (31 MN) needed to launch the Space Shuttle. This propulsion technology is under consideration as the way off the Moon for human explorers; such engines will most likely propel voyages from the Moon or send robotic expeditions to other planets in the solar system. 5.6 Safety:

Methane is not toxic; however, it is extremely flammable and may form explosive mixtures with air.5.7 Composition:Table 31: Methane Composition & %

Typical composition of biogasCompound Chemical %Methane CH4 50–75Carbon dioxide CO2 25–50Nitrogen N2 0–10Hydrogen H2 0–1Hydrogen sulphide H2S 0–3Oxygen O2 0–0

5.8 Fertilizer and Soil Conditioner:The solid, fibrous component of the digested material can be used as a soil

conditioner to increase the organic content of soils. Digester liquor can be used as a fertilizer to supply vital nutrients to soils instead of chemical fertilizers that require large amounts of energy to produce and transport. The use of manufactured fertilizers is, therefore, more carbon-intensive than the use of anaerobic digester liquor fertilizers. The notable advantage of using a bio-digester is the sludge which is a rich organic manure called digestate.






5.9 Waste Heat Recovery: Approximately 75 percent of fuel energy input to an engine is rejected as waste heat. Therefore, it is common practice to recover engine heat for heating the digester and providing water and space heat for the farm. Commercially available heat exchangers can recover heat from the engine water cooling system and the engine exhaust. Properly sized heat exchangers will recover up to 7,000 BTUs of heat per hour for each kW of generator load, increasing energy efficiency to 40 - 50 percent. A biogas fueled engine generator will normally convert 18 - 25 percent of the biogas BTUs to electricity, depending on engine design and load factor. 5.10 Biochemical Process:

Figure 9 Biochemical Process

The Biochemical digestion process is as follows: Bacterial hydrolysis of the input materials to break down insoluble organic

polymers, such as carbohydrates, and make them available for other bacteria.

Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids.

Acetogenic bacteria then convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide.

Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.

5.11 Physical Process: In the case of co-generation with biodegradable solid waste, after sorting or

screening to remove any physical contaminants from the feedstock, the material is often shredded, minced, and mechanically or hydraulically pulped to increase the surface area available to microbes in the digesters and, hence, increase the speed of digestion. 5.12 Alternative Biological Production routes:

Apart from gas fields, an alternative method of obtaining methane is via biogas generated by the fermentation of organic matter including manure, wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock, under


Carbohydrates

Amino Acids

HydrogenCarbon Dioxide

Ammonia

Fatty Acids

Carbonic Acids& Alcohols

Proteins

Sugars

FatsHydrogen

Acetic AcidCarbon Dioxide

MethaneCarbon Dioxide

Hydrolysis Acidogenesis Acetogenesis Methanogenesis





anaerobic conditions. Rice fields also generate large amounts of methane during plant growth. Cattle belch methane accounts for 16% of the world's annual methane emissions to the atmosphere. One study reported that the livestock sector in general (primarily cattle, and chickens) produces 37% of all human-induced methane. Early research has found a number of medical treatments and dietary adjustments that help slightly limit the production of methane in ruminants A more recent study, in 2009, found that at a conservative estimate, at least 51% of global greenhouse gas emissions were attributable to the life cycle and supply chain of livestock products, meaning all meat, dairy, and by-products, and their transportation. Many efforts are underway to reduce livestock methane production and trap the gas to use as energy. 6. Generation Process: 6.1 Optimum Conditions for Digester Operation:

Every application is different. In general, so long as the objective is to remove organic constituents, biological treatment is the most effective and most economical. Biologically, we can usually get BOD down to 1 or 2 parts per million with a successful treatment, yet certain applications require further reduction down to parts per billion levels. For this extreme reduction, chemical treatment would be necessary. For instance, biological treatment will never yield potable water. This must be achieved with chemical treatments like ozone and chlorine. Most applications consist of a primary, secondary and tertiary treatment, the primary being mostly physical like filtration settling, etc. The secondary is typically a biological treatment to organics. The tertiary treatment is a final, polishing and clarification treatment. It is typical that the tertiary treatment would incorporate some chemicals like polymers to aid in flocculation. In certain applications where there are no organics, it is appropriate to only use chemical treatment. For instance, a metal plating factory has only metals in the water. Bacteria will do nothing and a hydroxide must be used to chemically interact with the metal compounds and flocculate out. Activated carbon is a typical chemical treatment for final polishing of water. Polymers are used to further flocculate and settle colloidal solids. In certain applications in the past, the use of Bioaugmentation has allowed users to significantly reduce the amount of polymers being used in the final treatment without affecting solids settling characteristics. This will net a huge costs savings to the user. In general, most applications should incorporate a biological treatment. This treatment is usually good in most applications for discharge to the sewers or rivers. In most particular applications, chemicals can be used as polishers in the tertiary treatment. Chemical only treatments are only applicable in waters that have no organics, a situation that is very rare.6.2 System Management: The system manager must provide an acceptable work environment for micro-organisms by controlling the key operation parameters such as pH, temperature and oxygen levels. He must compensate them with nutrients to ensure good growth and a healthy population. He has to know when to lay off workers through wasting to keep the population young and vital. Finally, the successful system manager knows when to hire new workers to provide special skills not found in his workforce. Bioaugmentation is the mechanism to provide these skills workers.

The biomass is the "workforce" of a waste treatment system. In a dynamic state of flux, different microbes are dying while others grow and become more dominant. Under adverse conditions such as toxic shock, certain bacterial populations may be reduced or






eliminated, causing poor effluent quality. Examples of toxic shock would be black liquor spills in paper mills or a process upset in a chemical plant sending high levels of terpenes to the wastewater plant.

A critical part of the success of a bioaugmentation program is proper application. Because every system is unique, it is essential that products are properly applied. Bioaugmentation programs should be implemented with the help of qualified consultants capable of surveying the total system, assessing the best solution to the problem, and documenting the impact of the program. Simply dumping a product into the influent is not bioaugmentation.6.2.2 Preferential Degradation of Specific Compounds: By adding selected organisms, low levels of particular compounds can be achieved that are not possible with the indigenous population. Compounds such as phenols, chlorinated aromatics and aromatic hydrocarbons are but a few compounds that can be reduced with bioaugmentation 6.2.3 Improved Nitrification -- Many industrial waste plants have difficulty in achieving nitrification because of design limitations or toxic shocks. By regularly adding nitrifying bacteria, the proper population for ammonia removal can be maintained.6.2.4 Other Areas: Other areas where bioaugmentation offers benefits include odor reduction, oil and grease removal, rapid system start-up and improved tolerance to toxic shocks. 6.2.5 Purpose: The purpose of bioaugmentation is to facilitate a gradual shift in the microbial population, not to totally replace the existing biomass. The population shift must be accomplished in a planned and controlled manner to maintain the integrity of the microbial ecosystem. Over-feeding the selected microorganisms could result in a biomass no better equipped to handle the broad range of compounds in the influent than the original population.6.2.6 Method: Bio-augmentation dosage problems typically follow a descending application schedule to accommodate that fact that the benefits of the addition are multiplied. These programs usually involve a “purge” or “inoculation” dosage to establish the population quickly.

The “purge” or “inoculation” is followed by an intermediate maintenance dosage to support the development of the required population. Finally, a regular maintenance addition is used to maintain the required population to maintain the biochemical improvements, which have been realized through the “inoculum” and “intermediate maintenance” dosages.

Unlike that added to municipal sewage digesters, livestock waste is fairly uniform in composition. Monitoring digester operation, nevertheless, is a good idea and can be accomplished fairly easily, using gas production or pH of the digester liquid as an indicator. 6.3 Gas Production. This is the simplest and most reliable indicator. In a batch-loaded digester (one in which waste is added every month or so), if gas production drops off gradually, the food supply available to the bacteria is probably depleted, indicating it's time to add more waste to the digester. If gas production drops off rapidly (within 1 or 2 days), the reason is probably an upset digester. Among the potential causes, the major ones are: too high a level of toxic compounds in the waste feed, too high a feed rate or too cold a temperature in the digester.






A low digester temperature could be the result of a failure in the heating system. If a large amount of waste is added at one time, it should be preheated to 95F to prevent thermal shock to the methane bacteria. Better performance is usually obtained with continuous loading i.e. where the digester is loaded with smaller amounts of waste on a daily basis. 6.3.1 pH: A near-neutral acidity (pH=7.0) is a good indicator of proper operation. This means that the bacterial populations are in balance, with the `acid formers' producing only as much organic acids as the `methane formers' can use. A pH below 6.0 indicates a digester upset. Less-than-optimum environmental conditions can cause a digester upset, usually resulting in acid conditions. This is because acid-forming bacteria will thrive under a much wider range of environmental conditions than the slower-growing methane-forming bacteria. Acid conditions can be temporarily controlled by adding an alkaline substance such as lime. However, the original cause of the imbalance must be found and corrected if gas production is to be maintained.

Figure 10: pH Effects 6.3.2 Ammonia Concentration: As Ammonia is present in large quantities in urine it can inhibit methane production if present in large enough concentrations. Ammonia concentration at 1,500 parts per million (ppm) is considered to be the maximum allowable for good methane production. Above that level, the waste should be diluted with non-sewage water.

Effect of Ammonia Concentration on Methane Production:

Table 32: Ammonia Concentration Effect on Methane Production

Concentration(mg/l of Ammonia-N)

Effect

5 - 200 Beneficial 200 - 1000 No adverse effect1500 - 3000 Possible inhibition at higher pH ValuesAbove 3000 Toxic






6.3.3 Uniform loading: (preferably daily). 6.3.4 Key Consideration: Carbon: Nitrogen Ratio of the input material is the key consideration. This ratio is the balance of food a microbe requires to grow; the optimal C: N ratio is 20–30:1. Excess N can lead to ammonia inhibition of digestion. The primary limitation on co-generation of livestock waste along with liquid waste loading rates is the high nitrogen (N) content compared to its carbon (C) content. The ratio of carbon to nitrogen in manure added to the digester should be 20 parts C to one part N for optimum methane production.

Crop residues and leaves, which are usually low in nitrogen content but high in carbon, could be useful in improving digester performance. Mixing crop residue with high nitrogen livestock waste provides a more favorable C:N ratio; and gas production increases accordingly.

If the liquid waste; cow manure and crop residue/ leaves is not enough, for gas production requirements, it can be mixed with vegetable and food waste to cover the deficiency. However, this mixture has to meet certain conditions to be suitable for the digestion process.

This should never exceed a ratio of 35:1, and even 30:1 is quite high. A high ratio will slow the digestion process; a lower ratio will allow it to proceed well and will ensure a good fertilizer with high nitrogen contents. Substances with low ratio are unsuitable for open air composting because so much nitrogen is lost to the atmosphere, as soon as it is turned into ammonia. However, the Biogas plant avoids this, as the atmosphere is sealed, and the ammonia cannot escape.

Carbon: Nitrogen Ratios:

Table 33:C:N Ratios

# Material C/N N (% )

1 Urine 0.8 15 – 182 Blood 3 10 – 143 Cow Manure (dung) 25 1.7

6.3.5 Important Issue: The most important initial issue when considering the application of anaerobic digestion systems is the feedstock to the process. Almost any organic material can be processed with anaerobic digestion; however, if biogas production is the aim, the level of putrescibility is the key factor in its successful application. The more putrescible (digestible) the material, the higher the gas yields possible from the system.6.3.6 Establishment: Populations of anaerobic microorganisms typically take a significant period of time to establish themselves to be fully effective. Therefore, common practice is to introduce anaerobic microorganisms from materials with existing populations, a process known as "seeding" the digesters, typically accomplished with the addition of sewage sludge or cattle slurry.6.3.7 Suitability of Raw Material: Certainly, large quantities of antibiotics and cleaning disinfectants should be kept out of the digester. For this reason, consider excluding farrowing building waste from the digester. The antibiotic rumensin is also






toxic to methane bacteria and should not be fed to cattle whose waste is to be used for methane generation. 6.3.8 Percentage of Solids:

Ideally the slurry in a gas plant digester should be 7% - 9% solid material, pure manure is 18% dry matter; it must be diluted with a roughly equal part of water to achieve this level. If vegetable waste is added, more water will have to be added, depending on the solid content of the vegetable matter. It makes greater “ecological sense” to utilize sewage for this purpose.

If vegetable waste is used the gas plant should be provided with some kind of a mechanical agitation system, otherwise, the heavy leaves or straw will settle to the bottom and fermentation will be very slow.6.3.9 Temperature of Operating Cycle:

The operating cycle is the number of days after which with regular feeding and discharge of the gas plant, the entire contents are replaced by fresh material. At temperatures averaging about 75°F, manure will take about 50 days to be completely digested. Light vegetable waste will be digested in about 70 days at this temperature. A mixture of manure and vegetable waste will take about 50 - 60 days, depending largely on the quantity and the kind of the vegetable waste added. If temperature is artificially maintained between 90°F and 100°F, the fermentation period will not be more than 28 days for manure and 45 days for vegetable waste. Accordingly, large size plants that have such temperature control will be based on an operating cycle in this range.6.4 Digester Construction Requirements: 6.5.1 Insulating: Because temperature is critical to methane generation, heat conservation in the digester is essential. To utilize the insulating properties of the soil, consider mounding the soil up around the tank or burying the tank in a well-drained site so that the soil's full insulating potential can be realized Heating. The system most commonly used to provide a year-round 95F temperature for methane generation is a heat exchanger where hot water pipes are placed within the digester. The water can be heated outside the digester, possibly using a methane-fired water heater. For best results, waste should be preheated before adding it to the digester. As much as five times more heat may be needed for the preheating process as for maintaining digester temperature.6.4.2 Stirring. Mixing is important to ensure adequate contact between the bacteria and the waste and also to help strip gas out of the liquid. Mixing can be done using either:

Mechanical mixer. Compressor to bubble collected gas back through the digester liquid. Closed-circuit manure pump. A mechanical stirrer works well as long as a good air seal is maintained.

Atmospheric oxygen must be excluded from the digester, to eliminate the threat of explosion.

For the mechanical or pump-type methods, to determine the horsepower (hp) needed to mix the digester contents, use the equation: hp=0.185 x % total solids x liquid capacity (in 1,000 cft units).

For example, a 10,000-cubic foot digester containing waste at 6 percent solids would require a 11.1 hp mixer (0.185 X 6% X 10). As to frequency of stirring, some small-scale studies indicate that intermittent stirring (3-4 times per day) is about as effective as continuous stirring.






If a compressor is used for mixing, piping can be inserted into the digester, and recirculated gas from a storage unit injected by means of an open pipe or diffuser at the bottom of the tank. This creates turbulence and keeps the solids in suspension.

Any gas piping used should either slope back to the digester or have condensate traps to prevent water vapor from condensing and blocking the lines when the gas cools. Also, it is important that a gas meter be installed on the gas collection line in order to monitor digester operation; a high, stable gas production level usually indicates good operation.

Figure 11: Stirrer6.5 Digester Innovations: 6.5.1 Corn Cob Digesters

A laboratory study at Purdue University found that an anaerobic digester containing corn cobs can be used to treat swine waste and produce methane at temperatures as low as 65F. The study used a detention time of 5 days and a loading rate of 7.5 pounds of volatile solids per cubic foot per day. This system holds a great deal of promise for on farm use, with daily gas production as high as 1.5 volumes of gas per volume of digester.

Since the cobs are high in carbon but low in nitrogen, they improve the C:N ratio by supplying additional organic carbon. They also provide a support medium onto which bacteria can attach and be retained within the digester instead of being removed with the digester effluent. 6.5.2 An Energy Dome that combines liquid waste-treatment with biodegradable solid waste consisting of four, 30ft. domes (two each of Anaerobic and Aerobic Design) with allied equipment will optimally generate 10 MW-hours of electricity while treating 10,000 gallons (8% solid content) of waste per day. This is adequate to maintain 500 to 1,000 homes, depending upon energy requirements. An energy dome of this size, capable of generating 3,650 MW-hours annually and should cost under Rs. 20 million. This system costs less than coal or nuclear for initial set up as well as maintenance while remaining completely sustainable. The 3 inch concrete with Basalt Rebar dome's disaster-proof construction and adobe cover of 1 to 2 feet imparts the ultimate flexibility for architectural design. It is ideally suited for small as well as large-scale structures such as homes, shops, mosques, auditoriums, schools, athletic facilities, arenas, stadiums, gymnasiums, convention halls, stores, shops, and warehouses, including cold






store/freezer operations. Insulated concrete domes provide excellent energy efficiency. Heating and cooling a dome typically costs 1/4 to 1/2 less than a conventional building the same size. This cost savings has to do with how the dome is constructed. The thermal mass of the concrete and adobe combined create an R value of 50-60 with extremely low air filtration. Low maintenance is also a quality of a Monolithic Dome. Snow and rain cause very little stress on the exterior of a dome since its shape sheds water quickly. In a well constructed Dome leaks are rare compared to conventional domes and are easily repaired. The American Institute of Architects has acclaimed the geodesic dome "the strongest, lightest and most efficient means of enclosing space known to man". They handle hurricane winds, extreme snow loads and are the safest structure in an earthquake.

Figure 12: Geodesic Dome Bamboo Frame

7. “Makeen Qatil Makanoon Kay”Due to climate change and rising energy/ construction material costs as well as

prevailing construction practices that are outmoded and ill suited to local climate and culture, a need was felt to develop a viable alternate. Specifically after the Earthquake disaster in AJ&K and Hazara, it was realized that habitation of unsound architectural structures that are not suited, due to seismic instability as well as increasing heat/ cold, should be replaced with an adequate response. After many years of trial and error and much personal expense such a response has emerged. Refining the concept through expert input has always been a priority and has served to enhance the productivity and aptness as well as reduce the costs of such an endeavor. 7.1 Standing on the Outside, Looking In: The very word homeless evokes a feeling of pity and insecurity. The social animal that man is requires the safety and security of a shelter that belongs to him. A shelter wherein he can find peace and an opportunity to bring up his children. The self-respect and esteem that goes along with ownership of one’s own home, fosters a sense of well being and belonging. With this inborn craving once satisfied the individual can be expected to put in his best for the society that he belongs to. In no case should an individual or family group be made to feel as outcasts. To be exposed to the vagaries of nature or the arbitrariness of landlords leaves either a sense of despondency or else a growing frustration and inner rage against society. This must be addressed and removed






in a satisfactory manner. By this I mean to say that providing a. cheap and dingy hovel in sordid surroundings would aggravate rather then alleviate the problem. A way to provide inexpensive yet well suited; modern and indeed futuristic housing needs to be adopted.7.2 Present Trends: The present trends in building houses suffer from the following serious defects:7.2.1 “Israaf:” An Islamic term denoting ostentation. The vast amounts of money wasted on pomp and show is a sin and is strictly forbidden. This leads to fostering a sense of deprivation in the less fortunate sections of society as well as clearly depicts the owners of such ostentation as insensitive at the very least.7.2.2 Eco-Disaster: The very method of producing/ manufacturing building material is contributing towards an ecological disaster in the making. Bricks; Cement; Girders and other steel products; Crush; Sand and transportation are all based upon burning of fossil fuels on vast scales. This results in the emission of noxious gasses that greatly damage the fragile ecological system.7.2.3 Unaesthetic: The very attempt to produce fine homes proves to be a sore on the landscape and is totally out of place. This is all the more true due to mindless aping of the West and location of homes in a completely different environment from the original.7.2.4 Un-Scientific: The design and construction of these so called modern houses fail to take into consideration Solar Insolation; Prevailing Winds; Rainfall; Humidity etc. This results in enormous costs of heating and cooling. A waste that can be easily avoided or drastically curtailed.7.2.5 Expensive: Apart from ostentation the expenses involved in construction of relatively modest homes is enormous. This is very much beyond the reach of even the middle class.7.2.6 Non-Traditional: The adoption of non-progressive and indeed seriously flawed standards leaves us exposed to the charge of superficially following unsound practices. If the adopted course were one wherein advance is made and benefits accrued there would be no harm. However adoption of a course that leads to the afore mentioned deficiencies is ridiculous to say the least. Secondly a growing alienation and divergence from ones own culture and traditions is promoted for no possible gain.7.2.7 Site-Orientation: The first factor for planning a house is the location and orientation. Whereas location is often predetermined due to availability; inherent location defects can be overcome by means of correct orientation. The direction of window and door openings and their grouping is termed as the structures orientation. This is affected by the following: Table 34: Orientation Factors

# Major Factors1 Sun: This is the most important determining factor to make structure energy efficient.

A factor of increasing importance due to rising energy costs and global warming.






Solar angles vary from summer to winter and have to be taken into consideration depending upon site location where heat gain in summer and heat loss in winter is to be avoided

2 Wind: Prevailing winds of an area when catered for will provide ventilation in summer and prevent heat loss in winter.

3 Vegetation: Vegetation provides a host of uses from aesthetic to erosion/ dust noise control and insulation. This factor can also be actively used for income supplementation and/ or nutrition enhancement.

7.2.8 Energy Conservation: As mentioned previously this factor is of increasing importance and has become almost crucial. This aspect is addressed by the following; Table 35: Energy Conservation# Item:1Surface Area: Buildings with large surface areas will experience greater heat gain/ loss when least required. A circular configuration encloses the most space with the least wall area. This results in compact structures without compromising space availability.

2Roof Loads: Heavy roof loads for insulation require unconventional structural systems. The best of such systems is the Geodesic Dome. This design distributes the load evenly to all walls.

3Shuttering: An aspect that has fallen into disuse for no apparent reason. The use of slatted wooden shutters is of enormous benefit. The incorporation of directional skylights or windows facing south reflects sunlight into the house in winters but is screened out in summer with the change in the suns angle. The energy loss at nighttime is greatly reduced by using the insulated shutter in winters.

7.2.9 Thermal Characteristics: The inherent heat loss/ gain features of a structure are termed as its thermal characteristics.

Thermal Mass: This affects the heat capacity, which is the amount of energy required to change the temperature by 1 degree. A building with a large thermal mass within the insulation heats and cools at a low and slow rate. Whereas the opposite takes place at small thermal mass. Where temperature inside the building is more of question of survival rather then comfort this factor takes on increased importance. Passive solar use greatly diminishes requirements of external energy sources in winters.7.2.10 Earth Shelter: The interaction between roof; walls and floor is to a greater degree when earth shelter is used.7.2.11 Roof: The geodesic dome provides the least roof surface area of any structure. This combined with a thick earth berm around the walls leads to a high thermal mass. This results in moderate and stable heat gain/ loss. Shading by trees is much easier. If new planting is required the growing period can be covered by using green netting on bamboo






poles which is easier and uses less material then required for square or rectangular roofs, secondly use of fruit or vegetable vines is also easier.7.2.12 Walls: The door and window openings not only affect the strength of the building but also the net heat gain/ loss. Properly designed south facing openings, directly exposed to the sun in winters and shaded in summers should be used. These will provide a positive heating affect in winter and minimize gain in summer. Surrounding vegetation will decrease heat gain and consequent reflection/ conduction from the immediate vicinity.7.2.13 Floors: The interior temperature begins to rise due to warm/ hot incoming air or conduction in summer. An un-insulated floor responds by drawing heat out of the building at a greater rate in an attempt to maintain a steady temperature. Studies show that a three-fold increase in heat loss occurs in summer to aid in stabilizing the interior temperature to comfortable levels. A vapor barrier of existing roofing material under a relatively thin compacted floor will not act as a major impediment to this process.7.2.14 Basements: With additional increase in expense a sizable below grade, well type room can be added to the structure at any time without affecting the existing building. This room will have even more desirable thermal characteristics in extremely severe climates. In this case pre-cast concrete planks are used as roofing material/ floor of the above grade room. Since these possess poor insulation especially where waterproofing is not required, the heat loss characteristics are not affected. Indeed these can be positively aided by provision of exhaust/ covering with rugs. 7.2.15 Berming: Provision of a sloping earth berm around the structure will provide even greater insulation and lead to greater thermal mass. Secondly improved drainage characteristics can be readily incorporated. Thirdly utility rooms such as kitchen and bath/ washrooms can be conveniently built into these berms. Fourthly a greater degree of stability is ensured. 7.2.16 Internal Heat Gain: Depending upon the size and life style of the occupants there is a net heat gain inside the structure. This is estimated at 12 to 15 KwHrs per day in winter and 7 to 9 KwHrs in summers for a small household (5 to 7 individuals). A good cross ventilation plan and exhaust of kitchen heat to the outside will curtail this heat in summer. Retention of kitchen heat in winter and use of shuttering will add to comfort in winter. 7.2.17 Well-Designed Openings: Recessed and shaded openings will greatly add to prevention of heat gain/ loss when required. These will automatically aid in preventing entry of insects as well as dust into the interior of the house. Properly fabricated windows can provide net heat gain in winters. 7.2.18 Prevailing Adobe Homes: The concept of adobe housing is ancient and is still being used in many under-developed/ developing Countries. Inexpensive material and quick building have always been the hallmarks of such types of building. Insecurity of tenancy adds to the requirement of building an inexpensive and semi-permanent home. Crude and primitive, they nonetheless provide some features of climatic adaptation that are worth considering.






Table 36: Current Adobe Construction Climatic Adaptation Advantages

# Advantages: 1 Earthen walls gain and lose heat slowly.2 Material readily available, usually free of cost.3 Quick drying/ fast building.

Table 37: Current Adobe Construction Climatic Adaptation Disadvantages

# Disadvantages:1 Roofing gains and loses heat rapidly.2 Needs constant maintenance.3 Leaking roofs.

7.2.19 Geodesic Dome Construction: Table 38: Gedesic Dome Construction Advantages

# Advantages:1 Inexpensive and readily available Insulation materials (Clay).2 Quick to build. 3 Virtually indestructible.4 Fire proof.5 Insect proof.6 Earthquake proof.7 Waterproof.8 Highly hygienic.9 Low cost.10 Super Insulation.

Usual concepts of low cost houses are inefficient and depressing. This concept utilizes the extremely pleasing design of a Geodesic Dome and incorporates the advantages of Earth Sheltered and Passive Solar Techniques. 7.2.20 Weather/ Climate Orientation: In cold climates or hot areas the house is built facing the South for maximum solar gain in winters and minimum in summers. Prevailing cold and hot winds are also taken into account. 7.2.21 Location: This type of housing is highly adaptable in land use. However some disadvantages do crop up.7.2.22 Summary: Detached Units require from a minimum of 0.01 acres to 0.16 acres lot sizes. Four Unit Clusters require 0.25 acres while double Row Attached Units require as little as 0.018 acre lot sizes. This is by far the lowest of any type of construction while yet leaving a range from as low as 50 square feet per individual for an 8-member family. At present our less fortunate brethren are huddled together at intensities of 15 to 25 square






feet per individual and are cramped together in single rooms where cooking also takes place in rainy weather. The concept of attached bathrooms/ toilets is all together missing. Privacy is non-existent and this and the other factors have significant adverse impacts upon the psyches of the coming generations. The House thus provides the following additional advantages: Table 39: Advantages of Proposed Construction

# Advantages:1 More Space at low cost.2 More aesthetic surroundings for children.3 More Privacy.4 Space Age design acts as stimulus to imagination.5 More Privacy.6 Indoor Toilets provide hygienic surroundings.7 Stimulates Pride of possession.8 Raises self-esteem.9 Encourages Nation Building.10 Fosters Cohesiveness in Society.11 Removes Apathy.

7.3 Concept: The concept is based upon the Mongol folding Felt Tents (“Ger”: Origin of Urdu word “Ghar” or home) which incorporated for the first time the concept of Tension Bands and thus pre-empted discovery of this vital architectural principle. The concept was taken further by the Turks who named it as “Yurt” (Origin of the word and language Urdu as plural of “Yurt” to “Yurtu” or Army Camp). Muslim architecture incorporated the engineering excellence of the Dome as existing in harmony with the force of gravity as opposed to the flat roof of contemporary architecture. The development of the Geodesic Dome further increased the strength and engineering soundness of the concept. This development has been used extensively by me to erect Low-Cost Environment/ Predator Green/ Shade Houses for Kitchen Gardening. Here a wide variety of materials can be used to erect the requisite frame for the said purpose. Similarly, the concept has been taken further and adapted to meet the exacting climatic, expense and geo stability requirements that we face. 7.3.1 Effort: An effort was made to utilize locally available (NARC) construction material in the most efficient manner to establish Rapidly Erected, Low-Cost Dwelling for Field Research/ Development workers. The intended full scale model was for a 20 ft. diameter dome with 5 foot verandah, two bedrooms with one baths and one kitchen. The structure was to accommodate 4 workers or two officers. For Tsunami/ Violent Wind Storm proofing the structure was to be grouted on a reinforced concrete (40x40 ft.) pad. Unfortunately and despite expenditure of my own resources, using my own workers nd tools, the effort was called off due to differences between the Chairman PARC and his Federal Minister. This led to dismissal of th Chairman and all the people he had employed.7.3.2 Other Uses: The concept can, and should, be used for insulated cattle-sheds; poultry sheds; low-cost green houses or kitchen gardens for nutritional food security






called; cottage industry workplaces; mosques; grain silos; godowns; cold stores; Bio Reactors (for generating Methane for Direct combustion or Electricity generation utilizing sewage with no external energy input); shops, offices and other structures.7.3.3 The Design: The design consists of an aero dynamic geodesic dome that covers the most floor space with the least walls or roof and rests, but is not grouted to, a floor of 2 tons per square foot bearing capacity. This results in freedom for the structure to move with, rather than resist earthquakes up to 9 on the Richter scale. Secondly, the aero dynamic design does not oppose high velocity wind and allows it to flow over the structure thus providing capability to resist up to 250 mph winds. Rising temperatures in summer and increased cold in winters is resulting in increased need of energy for heating and cooling at a time when energy is scarce and prohibitively costly. This is yet another factor which is adequately catered for by emplacing the lowest possible cost and abundantly available adobe insulation material. Arising from the technology of our own cultural streams rather then the inappropriate western technologies, the concept is ready for ownership by our people. 7.3.4 Culture: The dome of Muslim architecture is the prototype of the Geodesic dome which is the strongest structure in an engineering sense and consists of 40 triangular facets. The compressional forces of traditional architecture are replaced by pre-stressed “tensional members” which is best described as “Tensigrity” or Tensional Integrity of the structure. Each member is linked to the other and passes on applied force to the others to provide equal strength of all members. Similarly, gravitational forces from below or impactional forces from above are not resisted but are allowed to flow through the structure.7.3.5 Structure: The structure consists of an RCC shell of 3 inch thickness that is covered with 1-2 foot adobe with a soil-cement layer upon curing. This system is capable of rapid erection by using permanent inner and outer shuttering, utilizing pressure filling of concrete over Steel Bar Re-enforcement (Rebar) or Basalt Rebar for lower carbon rating. Steps involved are; Firstly, construction of floor pad. Secondly; erection of inner shuttering. Thirdly, erection of outer shuttering and pressure filling; Fourthly, curing and removal of outer shuttering and finally emplacement of adobe cover and removal of inner shuttering. 7.3.6 Designing and Trials: Designing and trials of different versions for disaster proofing began after the 2005 EQ and built upon efforts at low-cost Ceramic Adobe Construction being studied and tried by the developer since 1990. At an R&D expense of Rs. 4.5 million (less personal time and effort) the final version is ready for mass dissemination. The existence of EQ Fault lines, storms and finally Global Warming accompanied with the equal and opposite reaction of increased cold in winters, demands that such methods of construction be immediately undertaken. Resistances to change and ingrained habits have to be abandoned in order to adequately respond to 21 st Century challenges. We have to live in harmony with nature in order to continue living at all! It is a pity that adequate attention is not being paid to the development despite or because of it being a win-win empowerment situation for all! 8. Size of the Plant:

The size of the plant is determined by multiplying the average volume of slurry to be fed per day as to supply the gas and fertilizer desired, by the number of days in the operating cycle. :






8.1 Sizing a Bio Gas Plant.In a two-stage digestion system (multistage), different digestion vessels are

optimized to bring maximum control over the bacterial communities living within the digesters. Acidogenic bacteria produce organic acids and more quickly grow and reproduce than methanogenic bacteria. Methanogenic bacteria require stable pH and temperature to optimize their performance. Under typical circumstances, hydrolysis, acetogenesis, and acidogenesis occur within the first reaction vessel.

The organic material is then heated to the required operational temperature (either mesophilic or thermophilic) prior to being pumped into a methanogenic reactor. The initial hydrolysis or acidogenesis tanks prior to the methanogenic reactor can provide a buffer to the rate at which feedstock is added. Some European countries require a degree of elevated heat treatment to kill harmful bacteria in the input waste. In this instance, there may be a pasteurization or sterilization stage prior to digestion or between the two digestion tanks. Notably, it is not possible to completely isolate the different reaction phases, and often some biogas is produced in the hydrolysis or acidogenesis tanks. Passive solar heating can be used to save on direct energy consumption.






Figure 13: Sizing a Digester8.2 Summary

This table summarizes the steps in designing a gas plant. The items in double boxes are the independent variables i.e. they are determined before any designing is done. The single boxed items are dependent variables. The plainly written items are free options which may be chosen on the basis of convenience and local conditions Thus production requirements determine how big a gas plant should be. With a small plant one has the options of one or two chambers in his digester, and with a big plant, one can choose between a single or double stage plant, or multiple single stage plants connected in series. Production requirements when considered together with the availability and suitability of the raw material determine the amount and type of the raw material to be used. Artificial heating and agitation is necessary for large plants, hence it is boxed. For small plants it is not always necessary. It only becomes necessary if the raw material used

Sardar Taimur Hyat-Khan. Email: [email protected] web: www.tamir-e-nau.org

REQUIREMENTS

Small Large

Single Chamber

Double Chamber

Amount & TypeOf Raw

Material Used

Single Stage

Double Stage

ArtificialHeating &Agitation

MultipleDigesters

ArtificialHeating &Agitation

Operating Cycle of the Plant

Size of Digester

Availability ofR aw Material

Suitability ofR aw Material

52





in a small plant contains vegetable matter. Hence it is semi-boxed to show that it is purely for a small gas plant.8.3 Double Stage: When such a large digester volume is required that construction in a single tank is impractical, the two stage gas plant is constructed. Here the digester volume is divided between two tanks. Digestion is carried out in the first tank until 80% of the total gas volume is evolved, and completed in the second tank. This necessitates the calculating of two operating cycles, and two volumes. The secondary digester is built without heating or agitation system, although it should have insulation. The primary digester should have all these. When the primary tank is operated with heating and agitation, 80% of the gas is evolved from fresh slurry after 15 days. This will be the operating cycle of the primary digester. Its volume should be sufficient to accommodate all the slurry fed in 15 days. A siphon transfers the slurry into the second digester when this volume is exceeded i.e. when the tank contains more than what will be fed in 15 days. The primary tank is intended mainly to produce gas. The function of the second digester is mainly to complete the decomposition. If gas is evolved so much the better, but the cooler temperatures present there might cause production to be quite low. Agitation' is not used because it would disturb the separation of the decomposed solid settled at the bottom, from the only partially decomposed slurry coming in from the siphon. Construction should be in cement and concrete. Since this material will absorb the gas a non-porous, non-absorbent coating must be applied to the inside right down to the level which is exposed to the gas.

Figure 14: Flow Chart Waste Disposal






9. Residual Products: The anaerobic digestion process produces:Table 40: Methane Production Residual Products

# Product1 Grease that, separated via further treatment, can be used as an alternative liquid fuel.2 Low-strength Liquid Wastes that can be fed into an on-site aerobic treatment plant.3 Class-A sludge (Digestate) with the potential to be used as a high-quality soil

amendment.4 Methane Gas Contaminants9.1 Class A Sludge: Digestate is the solid remnants of the original input material to the digesters that the microbes cannot use. It also consists of the mineralized remains of the dead bacteria from within the digesters. Digestate can come in three forms: fibrous, liquor, or a sludge-based combination of the two fractions. The second byproduct (Acidogenic digestate) is a stable, organic material consisting largely of lignin that cannot be broken down by the anaerobic microorganisms and cellulose. The biodegradation of the nitrocellulose compounds may be the most challenging step of the bioremedial process. However an alternative approach is to use known anaerobic bacteria often isolated in bovine rumens, or horse intestines3 that are capable of decomposing cellulose. The route which these type microorganisms use to degrade cellulosic compounds is through the production of important cellobiase enzymes, endo and exoglucanases, especially of fungal origin. It is proposed to use the species Clostridium cellobioparum, which have been found to effectively degrade cellulose under appropriate conditions, especially anaerobically. If this approach succeeds the digestate will not consist of significant volumes of cellulose. Also of a variety of mineral components in a matrix of dead bacterial cells; some plastic may be present. The material resembles domestic compost and can be used as such or to make low-grade building products, such as fiberboard. The third byproduct is a liquid (methanogenic digestate) rich in nutrients, which can be used as a fertilizer, depending on the quality of the material being digested. Levels of potentially toxic elements (PTEs) should be chemically assessed. This will depend upon the quality of the original feedstock. In the case of most clean and source-separated biodegradable waste streams, the levels of PTEs will be low. In the case of wastes originating from industry, the levels of PTEs may be higher and will need to be taken into consideration when determining a suitable end use for the material.

The digestate may contain ammonia that is phytotoxic, and may hamper the growth of plants if it is used as a soil-improving material. For these two reasons, a maturation or composting stage may be employed after digestion. Lignin and other materials are available for degradation by aerobic microorganisms, such as fungi, helping reduce the overall volume of the material for transport. During this maturation, the ammonia will be oxidized into nitrates, improving the fertility of the material and making it more suitable as a soil improver. Large composting stages are typically used by dry anaerobic digestion technologies The wastewater exiting the anaerobic digestion facility will typically have elevated levels of biochemical oxygen demand (BOD) and chemical oxygen demand (COD). These measures of the reactivity of the effluent indicate an

3 Shapton, 1971






ability to pollute. Some of this material is termed 'hard COD', meaning it cannot be accessed by the anaerobic bacteria for conversion into biogas. If this effluent were put directly into watercourses, it would negatively affect them by causing eutrophication. As such, further treatment of the wastewater is often required. This treatment will typically be an oxidation stage wherein air is passed through the water in sequencing batch reactors or reverse osmosis unit.9.1.1 Composting the Digestate:Table 41: Digestate Composting Advantages

# Benefits of Composting:1 Serves as the principal storehouse for anions such as nitrates, sulfates, borates,

molybdates and chlorides that are essential for plant growth. 2 Increases CEC (Cation Exchange Capacity) of soil by a factor of 5 to 10 times that of

clay. 3 Acts as a buffer against rapid changes caused by acidity; alkalinity; salinity; pesticides

and toxic heavy metals. 4 Supplies food for beneficial soil organisms like earthworms, symbiotic Nitrogen

fixing bacteria and mycorrihize (beneficial fungus). 5 Serves as recycling sink for organic waste and green manures (animal manure, crop

residues, household refuse and leguminous plants collected within and outside the farm) and thus keeps environment clean and hygienic.

6 Softens the soil by introducing fibrous matter. 7 Increases soil water retention capacity. 8 Makes plants more resistant to pests and disease through improved nutrient

availability and uptake, resulting in healthier plants with strong immune systems. 9 Prevents soil acidification.

Figure 15: Large Scale Composting

9.2 Gas Contamination and Contaminants: Raw biogas produced from digestion is not high quality enough to be used as fuel gas for machinery. The solution is the use of upgrading or purification processes whereby contaminants in the raw biogas stream are absorbed or scrubbed, leaving more methane per unit volume of gas. It takes roughly between 3-6% of the total energy output in gas to run a biogas upgrading system.

Definition: Process of removing one or more undesirable components from a gas stream.






Typically targeted at removing hydrogen sulfide (H2S), siloxanes, and particulates.

Optional removal of carbon dioxide, nitrogen, and water vapor for specific applications.

Digesters are known to contain undesirable components such as:

Figure 16: Digester Gas Contents Hydrogen Sulfide, H2S: 100 to 3,000 ppm: H2S gas when combined

with water vapor produces a weak acid: hydro sulfuric acid which is corrosive to metals in the combustion chamber as well as the intake and exhaust piping. It also produces sulfur dioxide during combustion. The corrosive nature of H2S alone is enough to destroy the internals of a plant. The addition of ferrous chloride, FeCl2, to the digestion tanks inhibits hydrogen sulfide production;

Volatile Siloxanes, 100 to 10,000 ppb: The word siloxane is derived from the words silicon, oxygen, and alkane. They belong to the wider class of organo-silicon volatile organic compounds (VOCs). Siloxanes can be found in products such as cosmetics, deodorants, de-foamers, toothpaste, water repelling windshield coatings, lubricants, food additives, and soaps. Most common siloxane types found in digester gas are the D3, D4, and D5 compounds.Such compounds are frequently found in household waste and wastewater

and are formed from the anaerobic decomposition of materials commonly found in soaps and detergents. During combustion of biogas containing siloxanes, silicon is released and can combine with free oxygen or various other elements in the combustion gas. It also forms deposits containing mostly silica (SiO2) or silicates (SixOy) and can also contain calcium, sulfur, zinc, phosphorus. Such white mineral deposits accumulate to a surface thickness of several millimeters and must be removed by chemical or mechanical means. Recommended target concentration: Target concentration in feed gas : <100 ppm Reciprocating engines and boilers: <100 ppb Turbines / Micro-turbines: < 50 ppb






Effect of Siloxanes:Siloxanes degrade to silicates (SiO2 & SiO3) at high temperature and

create impermeable glass particles. These particles bond onto hot metal surfaces. Reciprocating Piston Engines: Forms deposits and hot spots in the

combustion chamber, valves, valve seats, piston crowns and cylinder walls.

Boilers: Deposits a coating of silicate on boiler tubes that lowers heat transfer efficiency.

Gas Turbines: Deposits on turbine blades leading to blade erosion and a significant drop in operating efficiency.

Particulates: Form deposits on engine surfaces and boiler equipment.Water Vapor, H2O: 1 – 6%: Inert gas, lowers heat value of digester gas. “Wet” gas is more corrosive to machineryCarbon Dioxide: 35 – 40%Nitrogen, N2: <1%

9.3 Purification of Landfill and Digester Gas: Purification is done to remove harmful constituents within the stream. The addition of ferrous chloride, FeCl2, to the digestion tanks inhibits hydrogen sulfide production. The methane within biogas can be concentrated via a biogas upgrader to the same standards as fossil natural gas, which itself has had to go through a cleaning process, and becomes biomethane. The cleaned methane fuel may be pressurized into a high pressure fuel which is suitable for use with motors or vehicle engines adapted to be fueled by compressed natural gas. If the SNGPL allows for this, the producer of the biogas may utilize the local gas distribution networks. Gas must be very clean to reach pipeline quality, and must be of the correct composition for the local distribution network to accept.

First the Methane Gas is passed through a primary knockout pot that removes droplets, and filters matter from the Methane Gas.

The first segment of the duct passes through a series of three tubes that are filled with caustic soda that retains the CO2 emitted by the methane. The baking soda produced after CO2 reduction can also be a complementary source of revenue.

Next main vacuum and/or blower's pressure boost the gas to the appropriate conditions for moving the process gases as required. The hydrogen sulfide (H2S) removal system can either be a scrubber with solid media that absorbs the H2S in the Methane Gas stream or a liquid scrubber that catalytically converts H2S in the gas stream to solid sulfur. When using the second mentioned method, hydrogen sulfide removal produces inert element sulfur that can further purified for use as a secondary nutrient or even to stabilize Urea to avoid hydrolysis and volatilization when it is inculcated in the soil. This would also provide us with a double nutrient fertilizer. Alternatively it can be used as an additive for compost. This is in contrast to typical hydrogen sulfide removal processes that produce a hazardous waste element to be disposed of as hazardous waste if it is treated by the first mentioned method.

After the hydrogen sulfide removal process the gas moves to the siloxane removal equipment where siloxanes are removed by adsorption. The siloxanes removal system can be granular media scrubbers with re-generable or non-re-generable adsorbent media or a pressure swing adsorption (PSA) system, Vacuum Swing Adsorption system






(VSA), Temperature Swing Adsorption (TSA) system. The siloxane waste products are then disposed of with a small amount of Methane Gas in a flare or thermal oxidizer.

The resulting cleaned Methane Gas fuel is delivered as feedstock to the work application with clean, dry, filtered and temperature/dew point controlled fuel gas stream, without excessive hydrogen sulfide, and siloxanes after a final particulate filter to remove any entrained particulates in the gas stream. This stage may include Gas Conditioning.

A skid mounted gas drying system, including a moisture inlet coalescer, heat exchangers, chiller, pumps, moisture separator, recirculation bypass, and all piping, controls, and control panel consisting of:

Prime mover: Differential pressure blower, compressor, vacuum pump stage. This stage produces the required delta P to move the gas within the process stages, deliver it at pressures required for use in the engine/boiler user system. This stage moves from point to point within the flow path per job requirements.

Reasons for Gas Scrubbing:Table 42: Gas Purification Reasons

# Reason1 Decrease engine maintenance intervals2 Improve fuel (heat) value3 Improve engine performance providing more power!4 Sell gas to utility (pipeline quality)5 Produce compressed natural gas (CNG) for City fleet use6 Provide higher quality fuel to boiler7 Less maintenance

There are four main methods of biogas upgrading, these include:Water-washing: The most prevalent method is water washing where high

pressure gas flows into a column where the carbon dioxide which is soluble in water and other trace elements such as Particulates are scrubbed by cascading water running counter-flow to the gas. This arrangement could deliver 98% methane with manufacturers guaranteeing maximum 2% methane loss in the system. It takes roughly between 3-6% of the total energy output in gas to run a biogas upgrading system.9.3.1 Gas Scrubbing Technologies:

Adsorption (Dry Scrubbing) Molecular Sieve Media Adsorption: Component is adsorbed onto media the media is either exhausted and replaced or regenerated such as Iron sponge (iron oxide on wood chips) for removing H2S

Wet Scrubbing: Activated carbon, activated alumina for siloxane. removal






Figure 17: Wet Scrubbing

Refrigeration (Chilling): Mechanical refrigeration that removes moisture by lowering the temperature of the gas to condense the water vapor. Other impurities also removed in condensate.Removes: Moisture - dewpoint < 40ºF 90 - 100% particulates 70 - 80% siloxanes 20 - 30% H2S

Pressure Swing Adsorption (PSA): A mechanical pressure switching system that rapidly cycles from adsorption to regeneration. Uses molecular sieve media and other adsorption media to allow the passage of methane but rejects carbon dioxide, H2S, and siloxanesMolecular Sieve Media: Specialized adsorption media that traps (adsorbs) smaller molecules in media while allowing larger molecules to pass through. Media can be rapidly regenerated.Digester Gas Scrubbing: Traps carbon dioxide, nitrogen, and other smaller molecules while allowing methane to pass through media. Angstrom – length equal to 1 x 10-10 meters.

Figure 18: PSA Cycle






Pressure Phase: Adsorbing; Feed gas flows upward thru media bed. Targeted compounds are trapped or adsorbed in the media bed. CH4 passes thru the bed, over time the bed will become saturated.Vacuum Phase: Purging and Regenerating; Pressure is released thru the bottom of adsorbent bed.

Figure 19: PSA

Gas Scrubbing Approaches: Remove H2S, CO2, Particulates and SiloxanesUnit Processes in Series; Series of unit processes to remove each undesirable component.

Table 43: Purification Process

# Processes:1 Iron sponge. 2 Activated Carbon. 3 Chiller. 4 Wet Scrubber. 5 Adsorption.6 Pressure Swing Adsorption (PSA).

Schematic: Major Components of PSA Gas Scrubber Feed Compressor

Type: Reciprocating Capacity: 1 Million SCFD 60 HP Motor Compresses from 40-50 to 105 PSIG

Vacuum Compressor Type: Liquid Ring Capacity:0.5 Million SCFD 150 HP Motor Reduces from -3 to -18 in of HG•

Adsorber VesselsFour Adsorbers: On-line, De-pressurizing, Re-pressurizing, and Purging.

Buffer TanksTwo Equalization and Two Repressurization Tanks

Tail Gas BufferTank Purge Tank






Table 44: PSA Scrubbing Advantages

# Advantages of PSA Scrubbing:1 No consumables. PSA media has 5+ year life.2 Single process versus multiple processes.3 Less liquid discharge (compared to wet scrubbing for CO2 removal).4 Lower maintenance cost.5 Lower operating cost.6 Cost of the project.7 Received American Recovery and Reinvestment Act (ARRA) money for the project.8 Pay back period will be between 5-10 years.9 By using clean gas reduction in maintenance cost of the engines and boilers.10 Sell the gas to Gas Company or Build a CNG station.

10. Determining the Feasibility of Methane Production:The economics of methane production are generally considered questionable,

even at today's escalating fuel prices. But energy costs and availability tomorrow is changing this feasibility drastically. The following example, while by no means a complete economic analysis, should provide a rough idea of the value of methane generation. Example: Sr. Items and calculations ValueA. Determine potential volume of gas produced per day. 1. Gas produced per unit of input materials. 2. Total gas produced per day. Quantity of input x Step A.1 3. Total methane produced per day. Step A.2/ ½

B. Determine amount and value of energy produced. 1. Energy value per day. (Assumes ¼ of the methane must be recycled to provide

heat for the digester. As compared to cost of Natural Gas. Energy value of methane x usable methane x Step A.3 = BTU/day

2. Natural Gas equivalent of heat produced. Step B.1 / BTU/gal. Natural Gas 3. Rupee value of energy produced per day. Price of Natural Gas x Step B.2 4. Rupee value of energy produced per year. Days/yr. x Step B.3C. Determine digester tank volume and dimensions 1. Design liquid volume in the digester

Below Grade Volume 2. Total digester volume (including 1/2 day's storage for gas produced) in cubic feet. Step C.1 + (1/2 day x Step A.3) 3. Total digester volume in gallons. Gals./cu.ft. x Step 0.2 4. Dome dimensions.






5. Diameter of circular sump for height chosen. ((Step C.2 / Step C.4) x 1.27)1/2

D. Determine Digester Cost, including Insulation, Heater and Mixer. 1. Cost of digester, including pump. 2. Cost for digester insulation on cover and sidewalls. a. Insulation covering. (One way to insulate is to construct a larger diameter tank

around the digester and insulate the space between. The outer tank does not need to be as watertight or sturdy as the inner tank. Assume cost of the exterior tank is 1/2 the digester tank).

Step D.1 x 1/2 b. Digester sidewall surface area. Step C.4 x Step C.5 X 3.14 c. Digester cover area. (Step C.5)2 x 0.79 d. Total digester surface area. Step D.2.b + Step D.2.c e. Insulation cost. Insulating cost/sq.ft. x Step D.2.d 3. Cost of the water heater. a. Heater sized to supply 30 BTU per hour per cubic foot of digester liquid volume. Heater capacity/cu.ft. x Step 0.1. b. Heater cost. 4. Digester mixer cost. a. Mixer sized to stir digester contents having about 10 percent solids. Step C.1/1000 x pct. solids x 0.185 b. Mixer cost. (Assume a 3-in. diaphragm pump and piping system to re-circulate digester contents). 5. Total digester cost. Steps D.1 + D.2.a + D.2.e + D.3.b + D.4.bE. Determine the Cost of holding Digester Effluent Until Disposed. 1. Effluent produced per day in kgs. 2. Effluent produced per day in cubic feet. Step E.1 / kgs./cft. 3. Storage volume needed for x-day(s) capacity in cubic feet. Days capacity x Step E.2 4. Storage volume needed for x-day(s) capacity in gallons. Gals./cu.ft. x Step E.3 5. Cost for a prefabricated storage structure. Construction cost/gal. x Step E.4 6. Cost for an earthen storage structure. Construction cost/gal. x Step E.3 F. Determine cost of a gas storage unit.

A gas storage unit must also be constructed or else a use developed which consumes gas at the rate it is produced.

For this example, assume no gas storage is needed. G. Determine total cost of this methane generation system.






1. Total cost with a prefabricated storage. Step D.5 + Step E.5 2. Total cost with an earthen storage. Step D.5 + Step E.6 H. Determine the economic feasibility. (The Rupee value of methane produced in Step B.4 can be used to determine the payback period). 1. Capital investment that can be paid back in 7 years. 2. Total breakeven investment. Step H.1 – Total Investment. (In case of Carbon Credits attained or Cost Returned the situation will be different. However, it makes good economic sense to work out Economic Feasibility).11. Conclusion: By now, I am sure that all will agree that the discussed exercise is not only badly needed, it is also highly desirable and affordable. A CMD Project that commands carbon Credits is the requirement of the day. In this manner, given seed money for initial establishment, a recycling of Capital along with Socially Generated Waste is made possible. In this case we do not have to ask “How much will it cost, rather ask what will it cost not to implement the Project?”

Figure 20: Moving Towards the Future






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