WastewaterTreatmentManual Eng

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P REFACE

This Wastewater Treatment Guidance Manual is one of several outputs from the SMAP006SRY work entitled Integrated Coastal Management Project Between Jbail/Amsheet(Lebanon) and Latakia (Syria).

Financed by the European Union under the Mediterranean European Development Assistance(MEDA) Regional Indicative Program Short-term Mediterranean Action Plan (SMAP), the

project has been coordinated by ENVIROTECH LIMITED in Beirut and Damascus, andsupervised by both, the Ministry of Environment, Lebanon and the Ministry of State forEnvironmental Affairs, Syria with technical assistance from SIDI/EUROECO of Italy.

The Manual provides a general perspective of the alternative methods for managing and

treating them. It has been designed to assist decision makers in municipalities select theappropriate treatment option that best fits the quantity and quantity of the wastewater forwhich they have responsibility for treatment and disposal. Discussion therefore centres onthose options that are expected to be most appropriate for small and medium municipalities inLebanon and Syria, to whom the effective treatment and safe disposal of wastewater isrelatively new.


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INTEGRATED C OASTAL MANAGEMENT P ROJECT

WASTEWATER TREATMENT G UIDANCE MANUAL

T ABLE OF C ONTENTS

P REFACE T ABLE OF CONTENTS GLOSSARY OF TERMS

1. INTRODUCTION 2. P RELIMINARY TREATMENT 3. P RIMARY TREATMENT 4. S ECONDARY TREATMENT

4.1. S TABILISATION P ONDS 4.1.1. Anaerobic Ponds4.1.2. Facultative Ponds4.1.3. Aerobic or Maturation Ponds

4.2. S USPENDED GROWTH S YSTEMS 4.2.1. Activated Sludge4.2.2. Sequential Batch Reactor4.2.3. Aerated Lagoons

4.3. F IXED F ILM S YSTEMS 4.3.1. Conventional Biofilters4.3.2. Rotating Biological Contactors4.3.3. Biological Aerated Filters

5. TERTIARY TREATMENT 5.1. DISINFECTION

5.1.1. Chlorine Disinfection5.1.2. Ultraviolet Disinfection5.1.3. Ozone Disinfection

6. D ISPOSAL AND USE OF TREATED WASTEWATER E FFLUENT 6.1. W ASTEWATER RE-USE FOR IRRIGATION

7. TREATMENT AND D ISPOSAL OF S LUDGE 7.1. S LUDGE TREATMENT

7.1.1. Sludge Thickening7.1.2. Sludge Stabilisation7.1.3. Dewatering

7.2 S LUDGE DISPOSAL 7.2.1. Application of Sludge to the Land

8. E NVIRONMENTAL IMPACT ASSESSMENT 9. THE SELECTION OF WASTEWATER TREATMENT

9.1. FROM CONCEPT TO CONSTRUCTION ANNEX O NE . ENVIRONMENTAL LIMIT V ALUES FOR W ASTEWATER DISCHARGEANNEX TWO . W ASTEWATER TESTING L ABORATORIES IN LEBANON ANNEX THREE . TYPICAL TERMS OF REFERENCE FOR THE ENVIRONMENTAL IMPACT

ASSESSMENT OF A NEW WASTEWATER TREATMENT P LANT. ANNEX F OUR . D ATASHEET FOR THE S ELECTION OF W ASTEWATER TREATMENT

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G LOSSARY OF TERMS

AEROBIC Conditions that require the presence of oxygen

A NAEROBIC Conditions that exclude the presence of oxygen

BOD Biochemical Oxygen Demand, the amount of oxygen required for bacteria to decompose organic matter. Standard test conditions includedark incubation at 20C for 5 days, hence BOD 5

COD Chemical Oxygen Demand, the amount of oxygen required tooxidise organic and inorganic compounds. Water with a highBOD or COD contains organic materials such as algal and plantresidues and is rapidly depleted of oxygen

COLIFORMS A generic name for bacteria present in the intestinal tract of animals andhumans

DIURNAL Variations over a period less than one day.EFFLUENT Wastewater after the removal of the solids content

E NZYMES Proteins produced by living organisms that catalyse biochemicalreactions

FAECALCOLIFORMS

A coliform species, the presence of which indicates waste to haveoriginated from the intestinal tract of animals and humans

FOUL DRAINAGE A term commonly used to describe municipal wastewater or sewagedistinct from storm water drainage

HA Hectare, an area of 10,000m 2

HELMINTH A type of worm found in the intestinal tract of animals and humans

MG/L Milligrams per litre

LANDFILL A site approved and licensed for the disposal of solid waste

OXIDANT A substance that oxidises material with which it comes into contact

OZONE A form oxygen

PATHOGENS A substance causing disease

PRE-TREATMENT The treatment of industrial wastewater within a factory before beingdischarged into a public sewer

SLUDGE The solids content of wastewater that settles out during wastewatertreatment and remains after the effluent has been decanted off

TOC Total Organic Carbon, the standard measure of organic carbon inwastewater

TOXICITY The degree to which a substance is poisonous

TURBIDITY The degree to which a fluid is not clear due to the presence of fine particles in suspension

VIRUCIDE A substance that kills viruses


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INTEGRATED C OASTAL MANAGEMENT P ROJECT

WASTEWATER TREATMENT G UIDANCE MANUAL

1. I NTRODUCTION

Wastewater is the flow of used water generated by a community. It is usually characterised bya dark-grey colour, a musty odour and a variety of solids either in suspension or solution.There are three principal types of wastewater; Domestic, Industrial and Municipal.

Domestic Wastewater originates mostly from households, public facilities, and businesses. It includes liquid wastes from kitchens, bathrooms, and laundries, as well asany other wastes discharged accidentally or intentionally down the drain. Industrial Wastewater is the reject water from industrial processing and may contain awide variety of pollutants depending upon the range of activities undertaken in the

industrial area from which it originates. Municipal Wastewater consists of a mixture of domestic and industrial wastewater,and may also include storm water runoff from urban areas.

Wastewater is primarily composed of water (>99%), with relatively small concentrations ofsuspended and dissolved organic and inorganic solids. The organic content includescarbohydrates, lignin, fats, soaps, synthetic detergents and proteins, the products of theirdecomposition, and both natural and synthetic organic chemicals from process industries. Theinorganic content includes heavy metals, nitrogen, phosphorus, sulphur, chlorides and toxiccompounds. In domestic wastewater, the organic and inorganic contents are approximatelyequality distributed, with more dissolved than in suspension. Typically, 85-90% of the

inorganic content and 55-60% of the organic content are dissolved.Gases commonly dissolved in wastewater include hydrogen sulphide, methane, ammonia,oxygen, carbon dioxide and nitrogen. There is also a wide variety of pathogenic micro andmacro organisms including viruses, bacteria, protozoa and helminths.

Table 1 gives the primary characteristics of a typical domestic wastewater in countries such asLebanon and Syria.

T ABLE 1. T YPICAL P RIMARY C HARACTERISTICS OF DOMESTIC W ASTEWATER

C ONSTITUENT C ONCENTRATION (mg/l) C ONSTITUENT C ONCENTRATION (mg/l)

Dissolved solids (TDS) 250-1200 Sulphate (as SO 4) 50-150

Suspended solids 200-1000 Chloride 30-120

Nitrogen (as N) 30-180 BOD 5 200-800

Phosphorus (as P) 5-30 COD 400-1500

Alkalinity (as CaCO 3) 100-900 TOC 100-300

Notwithstanding the typical values given in Table 1, the character of wastewater varies with population density, average per capita discharge to sewers, degree of industrialisation, typeand size of the industrial facility, the degree of wastewater re-use, and any pre-treatment of


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industrial discharges. Wastewater characteristics also depend upon climate, seasonal variationin the use of recreational facilities and shorter-term diurnal changes.

Years ago, when all wastewater was discharged into natural watercourses, it was quicklydiluted and the microorganisms in the fresh water naturally consumed the incoming organic

matter. Increasing populations, population densities and the wide variety of modern industrialcompounds that find their way into wastewater have overwhelmed the natural purificationabilities of watercourses and discharges of wastewater now cause widespread environmental

pollution to the detriment of the landscape, flora and fauna, and public health.

Treatment plants are therefore required to clean wastewater before it is discharged into theenvironment. This is usually undertaken in four stages: Preliminary, Primary, Secondary andTertiary. Treated wastewater, both the cleaned fluid fraction, the effluent, and the settledsolids, the sludge, is a potentially valuable resource if it is safely and appropriately re-used.The cleaner the effluent and sludge required for final discharge or re-use, the further down thefour stages treatment has to progress.

Wastewater enters the treatment plant via the municipal sewage collection network. Ideally,this will comprise sealed subsurface pipelines to which all inlets are protected with a S, Uor similar trap of limited diameter, which restricts the size and type of waste that can bedisposed. However, both Lebanon and Syria have suffered a lack of regulation and openchannel foul sewers still exist in places. Storm water is also commonly discharged to fouldrainage networks. Open channels in particular afford the opportunity to dispose of largeitems of solid waste. Although recent and future construction provides for the separation offoul and storm water drainage, new wastewater treatment plants will, for the foreseeablefuture, need to cater for large items of incoming debris and a certain amount of storm runoff.The short duration heavy rainstorms experienced in the region frequently surcharge combinedcollection networks and overwhelm treatment works. Whilst it is reasonable to allow for somestorm water contribution to wastewater inflow, it is unreasonable, impractical anduneconomic to size treatment plants to cope with maximum storm flows. Secondary andtertiary wastewater treatment will be very expensive if it has to deal with large volumes ofstorm water. The capacity of the plant has to be much greater than would otherwise benecessary and the wastewater is more difficult to treat because biological activity is often lessefficient when the wastewater is highly diluted. Priority in network rehabilitation and newconstruction should therefore be given to separating foul and storm flows. When planningnew wastewater treatment plants, it may be necessary to dictate that certain sections of acommunity to be served are not connected to the plant until separation has been implemented.

2. P RELIMINARY WASTEWATER TREATMENT The main purpose of preliminary wastewater treatment is to remove large suspended particles.As raw sewage enters the treatment plant it passes through a bar rack or other type of screen,in which the openings are generally of uniform size. This retains larger items such as sticks,rags and plastics that may otherwise clog or damage the subsequent treatment stream. Barracks, commonly called trash racks, are normally used where particles, say 15mm or larger,are expected. Screens perform more effectively with particles less that 15mm. For the reasonsdiscussed above, it may be necessary to install both so the incoming sewage first passes the

bar rack and then the screen. To operate effectively, both have to be kept clean. Racks arenormally cleaned by hand, although for large plants, mechanical cleaners are available.

Screens are usually cleaned by a continuous water spray.

The material removed from the rack and/or screen is, subject to local municipal and site-specific regulations, usually acceptable for disposal in an approved landfill.


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After the coarse debris has been removed, the wastewater enters a preliminary settlement tankwhere grit and fine floating material is taken out. Grit, typically comprising sand, small stonesand food debris such as fragments of bone, broken eggshells and seeds, settles to the bottomof the tank. Floating debris, including oil and grease, forms a scum on the surface and is

skimmed off, either mechanically or by hand. The removal of grit is particularly important intreatments plants serving communities with a combined foul and storm water collectionnetwork, where grit, stones and even broken road surfacing is washed in during heavyrainfall.

3. P RIMARY WASTEWATER TREATMENT

The main purpose of primary treatment is to remove the remaining suspended solids. This isgenerally achieved by sedimentation, but since the particles remaining in suspension are nowsmall in size, they only settle out slowly and a longer retention time is required than for theremoval of grit and coarser particles. An extended retention time is achieved by reducing theflow rate through the settlement tank and is most easily accomplished by using a larger anddeeper tank.

Also during primary settlement, grease and other floating matter accumulates on the surfaceof the wastewater, from where they are skimmed off and taken with the sludge for furthertreatment or disposal.

The typical process stream for preliminary and primary treatment is shown in Figure 1.

F IGURE 1. T YPICAL P RELIMINARY & P RIMARY T REATMENT STREAM .

4. S ECONDARY WASTEWATER TREATMENT

With the inflow to the treatment works now clear of course debris and most dense suspendedmaterial, the process of removing organic pollutants and reducing pathogens can begin. Thisis accomplished by biological processes in which optimum conditions are provided for thegrowth of microorganisms that decompose and digest the waste. For communities where thewastewater predominantly comprises domestic sewage, one of three systems is usuallyemployed: Waste Stabilization Ponds, Suspended Growth Systems or Fixed Film Systems

4.1. W ASTE STABILIZATION P ONDS

Waste stabilization ponds comprise a series of Anaerobic, Facultative and Maturation orAerobic ponds. Such treatment systems may be constructed singly, with others added in

parallel as the volume of wastewater increased with urban expansion.

Sludge


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4.1.1. Anaerobic Ponds Anaerobic ponds are typically 2-5m in depth and their primary function is to reduce BODcontent. Some reduction in pathogens also takes place. They are loaded at a relatively highrate to ensure dissolved oxygen is absent so the settled solids can undergo anaerobicdecomposition. Retention time is short; 1-2 days for a raw wastewater BOD of 300 mg/l at

15C. Efficient anaerobic ponds typically reduce BOD by 40% at 10C and by 60 % or moreat 20C.

4.1.2. Facultative PondsFacultative ponds are typically 1-2m in depth and have the same function as anaerobic ponds.They are loaded in such a way as to develop two layers within the wastewater body, anaerobic layer at the surface and an anaerobic layer, which contains the sludge, at depth.Oxygen, produced by surface aeration and photosynthetic algae, affects the reduction in BOD.

4.1.3. Aerobic or Maturation Ponds Maturation ponds are typically 1-1.5m in depth and several are often constructed in series.Their primary function is to reduce pathogens. Some reduction in BOD also occurs. They areoften used where the effluent from facultative ponds is unsuitable for re-use. The

bacteriological quality of the final effluent required governs the size and number of thematuration ponds. A retention time of several days is usually needed to ensure a substantialreduction in pathogens is achieved.

4.2. SUSPENDED G ROWTH SYSTEMS

Suspended growth systems are one of the most common forms of wastewater treatment forsmall communities. There are three principal types: Activated Sludge, Sequential BatchReactor and Aerated Lagoons.

4.2.1. Activated Sludge This process produces an activated mass of microorganisms to stabilise the wastewateraerobically. Oxygen is supplied to the aeration zone to initiate sludge decomposition and

provide agitation to promote the flocculation of fine particles, which then settles out. Becausethe bacteria have short life cycles, some of the settled sludge is recirculated within the processto maintain the required concentration. Typically about 85% of accumulated sludge isremoved for disposal, with 15% being recirculated. Two types of activated sludge process arein common use:

Conventional Activated SludgeIn the conventional system, the raw wastewater enters a primary settlement tank whereheavy solids settle out and floating material is trapped at the surface. These materialsare removed as necessary, typically every 4-12 months. A three-hour retention time inthe separation tank typically gives a 25-40% reduction in BOD and a 50-70% reductionin suspended solids.The wastewater then enters an aeration tank where oxygen pumped from the bottomsustains the microorganisms that affect decomposition. After a typical retention time of4-8 hours, the majority of fine particles have flocculated and begin to settle. The fluidcontent then passes into the clarifying tank where after 3-4 hours; the sloped baseguides the flocculated material to settle towards the centre. A skimmer may be used toremove any remaining surface scum. The treated wastewater is taken off for disposal orre-use and some of the activated sludge is returned to the aeration tank to maintain

bacteriological activity. The remaining sludge, typically 60-70 %, passes into an aerobicdigester where it is stabilised until suitable for final disposal.


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Extended AerationThe primary settlement tank and aeration tank perform in much the same manner as inthe conventional system, except that the extended aeration requires an increasedretention time and a decrease in organic loading. In the digester, the sludge may befurther aerated until it has stabilised and is suitable for final disposal.

A variation of the activated sludge process is a Deep Shaft installation, where thewastewater treatment stream is arranged vertically, within a shaft typically 50-100m deep and1-2 m diameter, instead of horizontally along the ground surface. Since treatment isundertaken below ground, variations in treatment efficiency due to changes in ambienttemperature, rates of loading and, perhaps, flow rate, may be reduced. Because compressedair at a high pressure is used to aerate and maintain circulation, the transfer of oxygen is moreefficient and BOD, COD and suspended solids removal may be better. Sludge volume isreduced and subsequent digestion may not be required. A lower land take is required andhence environmental impact is reduced. However, construction costs are higher that for atreatment stream at ground level and vary with the physical characteristics of the site.

Construction may also be problematic in areas of hard rock, such as the karstic limestones thatare common in Lebanon, and/or in areas with a high water table. The long-term stability ofdeep shaft wastewater treatment may also be subject to instability in areas of seismic risk,which in Lebanon is high.

4.2.2. Sequential Batch ReactorSequential Batch Reactor treatment is similar to the activated sludge system except thataeration, sedimentation and clarification of a single batch of wastewater is carried out in thesame tank, in five sequential steps. Raw wastewater is added to residual fluid from the previously processed batch during theFill stage. Typically, 25% of a previous batch remains in the tank and the fresh input for the

new batch is 75% of the tank volume. Aeration during the Reaction stage continues until biodegradation of BOD and nitrogen is achieved, after which the fluid is left to stand so themicroorganisms dying from the lack of nutriens help reduce the volume of sludge as it settlesout. On completion of the Settlement stage, a layer of clear treated effluent is left above a

blanket of sludge. The effluent is carefully decanted off for re-use during the Draw stage, ina manner that does not disturb the sludge. The final Idle stage of the process allows time forsludge removal, and for the filling of other reactors where several are constructed in parallel.Depending on the size of the treatment plant, the volume of each batch, and the nutrientloading, sludge removal may not be required after every batch is processed, and may only benecessary every 2-3 months.Because the process utilises one tank, a second or more reactors, or ponds for the storage of

raw sewage awaiting treatment, are necessary to cope with a continuous inflow of wastewater.4.2.3. Aerated Lagoons Aerated lagoons are similar in concept, but generally comprise shallow basins of minimumdepth 1m in which wastewater is treated by contact with the suspended solids. Oxygen issupplied to promote bacteriological activity and maintain the solids in suspension. A separate

basin or tank is often provided to allow treated effluent to be recirculated through the processto improve its quality to a standard suitable for re-use.

4.3. F IXED F ILM SYSTEMS :In fixed film systems, raw wastewater is discharged onto a filter medium to which the bacteriacling until they build up to the extent they fall off. Three types of fixed film systems are incommon use: Conventional Bio-filters, Rotating Biological Contactors and BiologicalAerated Filters


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4.3.1. Conventional Bio-filters Also known as trickling filters, the raw wastewater is slowly but continuously discharged ontonaturally well-ventilated medium, most often circular beds of rocks or sheets of corrugated

plastic. Microorganisms attached to the surface of the filter medium degrade the organiccontent of the wastewater. As the bacteria build up they become heavy and are swept away by

the incoming wastewater, leaving space for new growth. The wastewater passing the filter issettled out and the treated effluent and sludge separated.

4.3.2. Rotating Biological Contactors Rotating Biological Contactors, comprise a series of closely spaced circular disks that are

partly submerged in the wastewater and slowly rotated. Biological growth attaches to thesurface of the disks and rotation allows sufficient oxygen transfer to maintain aerobicconditions. Again, the bacteria eventually become heavy, fall off, and are settled out.

4.3.3. Biological Aerated Filters Biological Aerated Filters consists of a submerged inert support media on which bacteriaagain grow and degrade the organic content of the wastewater. Aerobic conditions aremaintained by blowing air through the submerged media.A comparison of technical performance and economics of secondary wastewater treatmentsystems most commonly used for small towns and villages where wastewater is primarilydomestic in origin is shown in Table 2.

T ABLE 2. C OMPARISON OF SELECTED SECONDARY W ASTEWATER T REATMENT SYSTEMS 1 SUSPENDED G ROWTH F IXED F ILM

C RITERIA STABILIZATION

P ONDS ACTIVATEDSLUDGE

E XTENDEDAERATION

AERATEDL AGOONS B

IO -F ILTERS

T ECHNICAL

P ERFORMANCE

BODFaecal ColiformsSuspended SolidsHelminthViruses

******

*******

*

*****

**

***

******

**

***

*

***

E CONOMICS

ConstructionOperationLand TakeMaintenanceEnergySludge Removal

******

*********

*** *

*** *

* * *

*

******

Poor * Fair .*** Good

Some systems rely upon the addition of enzymes to promote chemical action, enhance the biodegradation of wastewater, and reduce the volume of sludge. Since they also dissolvegrease, fats, starch and protein, and reduce odour, they also improve effluent quality.However, the cost of enzyme dosing is high and is usually avoided wherever possible.

On completion of secondary wastewater treatment, effluent and sludge remain. The effluentwill still contain organic, inorganic and pathogenic microorganisms that need to be furthertreated before it can be discharged into the environment, either for re-use or final disposal,without risk to public health, fauna, flora or water resources. The sludge, from both primaryand secondary settlement, will still have a high water content and needs to be further treated

prior to use as a soil conditioner or final disposal. Both effluent and sludge will also contain pollutants from the inflows from industrial areas and highway drainage, and therefore require

further treatment

1 Arthur, J.P. 1983. Notes on the design and operation of waste stabilization ponds in warm climates ofdeveloping countries. World Bank Technical Paper No. 6. World Bank, Washington DC.


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5. TERTIARY TREATMENT To improve the quality of secondary treatment effluent, tertiary treatment commonly employsone of the following procedures:

Rapid Sand Filtration to further reduce suspended solids and turbidity. Nitrification or Denitrification to remove nitrogen either by converting

ammonia to nitrate (Nitrification) or reducing nitrate and nitrite to nitrogen gas(Denitrification).

Carbon Adsorption to remove the remaining soluble organics. Disinfection to reduce the number of waterborne pathogens.

Disinfection is the most commonly used for villages and small towns where wastewater is primarily domestic and for the purposes of the present Guidance Manual, is the only methodof tertiary treatment discussed further.

5.1. DISINFECTION

Disinfection is the primary method of destroying pathogenic organisms to prevent the spreadof waterborne diseases, but it is important the effluent has been adequately treated for thedisinfectant to be effective. The selection of the most appropriate method of depends oneffluent quality, potential toxic effects, ease of operation and maintenance, and regulationsregarding residual disinfectant for different re-use and final disposal options. The mostcommon methods of disinfection are chlorination, ultraviolet light radiation, and ozonation.

5.1.1. Chlorine Disinfection Chlorine may be applied as a gas, as pure chlorine or chlorine dioxide, as an ionised solid, orin chlorine compounds such as calcium hypochlorite or sodium hypochlorite (bleach). Theadvantages and disadvantages of chlorine disinfection are as follows:

Advantages Disadvantages Provides a residual disinfectant for subsequent protection.Residual chlorine is easy to measure.Chlorine is readily available at reasonable cost.Low energy costs.Applicable for multiple effluent quality problemssuch as bacteria, iron, manganese and hydrogensulphide.Can be used to treat large volumes of effluent.Can be applied in different forms to suit differenteffluent qualities.Operational procedures such as contact time and

dosage are easily managed.

Requires a minimum contact time of thirty minutes.High turbidity reduces effectiveness.Chlorine residuals and by-products may be releasedinto the environment.Free chlorine is toxic to aquatic life and is suspected to

become carcinogenic if it reacts with organic material.Toxicity increases with decreasing effluent pH andincreasing temperature.Health risks to those handling chlorine includeirritation of mucus membranes, respiratory tract, eyesand skin, and may cause pulmonary oedema and death.Liquid chlorine reduces body heat and freezes exposed

skin.

5.1.2. Ultraviolet DisinfectionUltraviolet (UV) disinfection utilises electromagnetic energy from a mercury arc lamp toirradiate the wastewater effluent and kill the microorganisms. Critical issues in the processinclude effluent quality, UV intensity, exposure time, and equipment configuration. Thehigher the turbidity and suspended solids content of the wastewater, the lower the adsorptionof the radiation. The optimum wavelength is 250-270nm and the lamps need to be properlymaintained. There needs to be a uniform flow of effluent past the lamp and sufficient radialmixing to maximise exposure. The advantages and disadvantages of ultraviolet disinfectionare as follows:


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Advantages Disadvantages Affective on most viruses, spores, and cysts.UV equipment is compact and easy to use.Requires a very short contact time.Produces no residual disinfectant.

High energy and maintenance costs.Requires effluent of low turbidity and suspendedsolids.

5.1.3. Ozone Disinfection Ozone is a very strong oxidant and virucide. Because it is unstable and quickly decomposes, itis generated on site by passing a high voltage current, 6-20kV, between two electrodescontained within an oxygen-bearing gas. The effectiveness of ozonation depends on thesusceptibility of the target organisms, the contact time, usually 10-30 minutes, and ozoneconcentration. It has the ability to achieve higher levels of disinfection than either chlorine orUV disinfection, but being more expensive is only used where the alternatives are lesseffective. The advantages and disadvantages of ozone disinfection are as follows:

Advantages Disadvantages Effective in destroying viruses and bacteria.Requires a short contact time, 10-30 minutes.

Provides good odour control

Capital and maintenance costs can be high.Equipment has to be corrosion-resistant.

Causes irritation and may be toxic.

6. DISPOSAL AND USE OF T REATED W ASTEWATER E FFLUENT For any given wastewater, the selection of a treatment stream depends on the destination ofthe treated effluent. The levels of treatment required for the most common destinations aresummarised in Table 3.

T ABLE 3.T REATMENT R EQUIREMENTS FOR SELECTED E FFLUENT DESTINATIONS 2

DESTINATION P RELIMINARY

T REATMENT

P RIMARY

T REATMENT

SECONDARY

T REATMENT

T ERTIARY

T REATMENT IrrigationProduce eaten raw Yes Yes Yes YesOther produce Yes Yes Yes NoPublic gardens Yes Yes Yes YesGroundwaterrecharge

Yes Yes Yes Yes

Disposal to a surfacewatercourse

Yes Yes Yes No

Disposal to the sea Yes Yes Yes No

Details of the Lebanese and Syrian standards for the quality of wastewater discharged aregiven in Annex One.

6.1. W ASTEWATER R E -USE FOR IRRIGATION

Irrigation with treated wastewater requires measures to prevent public health, salinity andtoxicity hazards. Effluent of a high biological quality is necessary for the irrigation of certaincrops, particularly vegetables and other produce that may be eaten raw. A lower quality isacceptable for crops that are processed or where there is no direct exposure to the public. Themost important criteria are those that safeguard the health of farmers, farm workers, producehandlers and consumers. The primary indicators of health risks are the levels of faecal

2 Ministry of Hydraulic & Electric Resources, , Standard Practice Document SPD9 - Wastewater Treatment, prepared by Sector Implementation Unit (SIU-1)Water and Wastewater Sector, updated June 2001.


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coliforms and helminth eggs for which the World Health Organisation has set the guidelinesshown in Table 4.

T ABLE 4. G UIDELINES FOR THE USE OF T REATED W ASTEWATER IN AGRICULTURE 3 A

C ATEGORY I NTENDED R E-USE G ROUPS AT R ISK

INTESTINALNEMATODES b

(arith. mean no.eggs/l) c

F AECAL

COLIFORMS (geom. mean no.coliforms/100ml)

R ECOMMENDEDW ASTEWATERT REATMENT

A

Unrestricted irrigationCrops likely to be eatenuncooked.Spray-irrigated fruits.Sports fields.Public parks. d

WorkersConsumer

sPublic

1 103

A series ofstabilization ponds orother treatment

process designed toachieve the qualityindicated, orequivalent treatment

B

Restricted irrigationCereal, industrial andfodder crops.Some vegetables noteaten raw, e.g. potatoesPasture and trees. e

Workers 1 No standard

Retention instabilization ponds for

8-10 days or other process to achieve theequivalent helminthand faecal coliformremoval

C

Localised irrigation ofcrops in category Bwithout exposure toworkers or the public

Not applicable Not applicable

Pre-treatment asrequired by theirrigation method, butnot less than primarysedimentation.

a In specific cases, local epidemiological, socio-cultural and environmental factors should be taken into account, and theguidelines modified accordingly.b Ascaris and Trichuris species and hookworms.c During the irrigation period.d A more stringent guideline ( 2000 faecal coliforms/100 ml) is appropriate for park lawns to which the public haveunrestricted access.e In the case of fruit trees, irrigation should cease two weeks before fruit is picked and no fruit should be picked off the

ground. Sprinkler irrigation should be used.

Dissolved salts and toxic ions present in treated effluent arrest plant growth, crop yield and produce quality. Salt may cause soil salinisation, which lowers fertility. Not all plants respondequally. There is a wide range in the tolerance of specific crops to salinity and toxicity andcareful selection allows a greater use of wastewater for irrigation, thus preserving fresh waterresources for potable and more critical uses. There is a wealth of information on the toleranceof specific crop species, but for the purposes of the presence Guidance Manual, an indicationof the salinity tolerances of common crops and the threshold levels of selected trace elementsfor crop production are given in Tables 5 and 6 respectively.

3 WHO 1989. Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture.Technical Report No. 778. Geneva 74 p.


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T ABLE 5. SALINITY T OLERANCES OF M AJOR C ROPS C ROP T YPE T OLERANT M ODERATELY T OLERANT M ODERATELY SENSITIVE SENSITIVE

FIBRE , SEEDAND SUGARCROPS

Barley, Cotton,Sugar Beet

Oats, Rye, Sorghum,Soybean, Wheat

Broad Bean, Maize, Flax,Millet, Groundnut, SugarCane, Sunflower

Guayule, Sesame

GRASSES AND

FORAGE CROPS

Bermuda Grass,

Salt Grass

Canary Grass, Fescue,

Rape, Sudan Grassl

Alfalfa, Clover, Orchard

Grass, Vetch

VEGETABLES Asparagus Artichoke, Beetroot,Squash

Broccoli, Cabbage,Cauliflower, Celery, SweetCorn, Cucumber, Eggplant,Lettuce, Pepper, Potato,Pumpkin, Radish, Spinach,Tomato, Water Melon

Carrot, Okra, Onion,Parsnip

FRUIT AND NUTS Date Palm

Fig, Olive, Papaya,Pineapple, Pomegranate Grape

Almond, Apple, Apricot,Avocado, Cherry,Grapefruit, Lemon,Lime, Mango, Orange,Peach, Plum,Strawberry,

T ABLE 6. T HRESHOLD L EVELS OF SELECTED T RACE E LEMENTS FOR C ROP P RODUCTION 4 T RACE

E LEMENT RMC 1 (mg/l) C OMMENTS

Aluminium 5.0 Causes non-productivity in acid soils (pH 7.0) will precipitate aluminium and eliminate toxicity.Arsenic 0.10 Toxicity varies from 12mg/l for Sudan grass to


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7. TREATMENT AND D ISPOSAL OF S LUDGE On completion of primary and secondary treatment, sludge still contains 0.5-8 % of solids thatadversely effect public health and the environment.

7.1. SLUDGE T REATMENT

There are a number of options for sludge treatment, which may be utilised either separatelyor, if a high quality end product is required, sequentially. These are primarily thickening,stabilisation and dewatering. In all options, the fluid content taken out is recirculated backinto the treatment plant.

7.1.1. Sludge ThickeningThickening is used to separate the water and solid fractions of the sludge before stabilization,to reduce sludge quantity and stabilisation costs. A variety of procedures are available.

Gravity Thickening: The sludge settles and compacts within a circular tank and thethickened product is drawn off from the bottom.Gravity Belt Thickening: After the addition lime, ferric chloride or polymers toincrease the solids content, the sludge is spread onto a permeable moving belt throughwhich excess fluid drains.Flotation Thickening: Air is pumped through the storage tank, bringing the solids tothe surface from where they are skimmed off.Centrifugal Thickening: Rotation of the tank promotes the accumulation of solids onthe walls, from where they are removed.

7.1.2. Sludge StabilizationStabilisation minimises health hazards by reducing the number of pathogenic organisms

present, including odour-producing organisms. Again, the selection of stabilising processdepends upon sludge characteristics and its subsequent destination. The options includeanaerobic digestion, aerobic digestion, composting and lime stabilisation.

Anaerobic DigestionIn the absence of oxygen, organic compounds are converted to gas, primarily methane(65-70%) and carbon dioxide (25-30%), with small amounts of nitrogen, hydrogen andwater vapour. Anaerobic digesters are generally of two types. Low rate digesters areutilised where the input is less than about 40l/s and the sludge has a solids content

below 10%. High rate digesters are utilised for greater quantities and/or where the solidscontent of the sludge may be up to 20-30%. Both types utilise a conical tank, with a gastake-off at the top and a sludge take-off below a sloping base. In low rate digesters, theretention time is typically 30-60 days, raw sludge is added intermittently and there is nomixing other than that resulting from the natural rise of the gases. A secondary heatingsource may be used to increase the rate of digestion. In high rate digesters, raw sludge isadded continuously, and both heating and mechanical mixing is routine.Aerobic DigestionAerobic digestion oxidises organic matter into carbon dioxide, water, and ammonia ornitrates. The process operates at temperatures of 20-30C and air is pumped in to

provide the oxygen to promote biological activity. Aerobic digesters are manufacturedfor either batch or continuous operation. Composting Composting is the biological degradation of organic matter under aerobic conditionsand is the most common process used to stabilise wastewater sludge to be used for soil

conditioning. The organic matter breaks down to carbon dioxide, water, heat, andcompost. To ensure optimal conditions for biological activity, the carbon and nitrogencontent need to be adjusted so that there is 25-35 parts carbon to 1 part nitrogen byweight. A lower ratio can give rise to odorous ammonia; a higher ratio will not give


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optimal conditions, degradation will be slower and temperatures may be inadequate for pathogen destruction. Sludge is rich nitrogen and must be mixed with a carbon-rich bulking agent such as wood chips, sawdust, newspapers or hulls. The bulking agent alsoincreases the porosity of the mixture, improving the availability of oxygen to the centreof the composting mass. Air can be pumped in, but passive techniques for its

introduction, such a periodic turning of the mass, are more commonly applied. A variety of different composting systems are available. These include compostingwithin a closed container into which air is pumped, within a container that ismechanically turned and mixed, and within a static pile, with air pumped in at the

bottom and the pile covered with previously composted material. Lime StabilisationLime is added to sludge to increase the pH to 12, at which organic matter is destroyedor rendered inactive after 2-3 hours. The types of lime most commonly used areQuicklime and Hydrated Lime. Quicklime is considerably cheaper than Hydrated Lime

but use of the latter requires less labour and equipment as it is already hydrated. Thismethod of stabilisation is likely to have only limited application in Lebanon. Over 60%of the country is underlain by limestones, which give rise to naturally lime-rich soils.The addition of extra lime may therefore hinder plant growth, crop productivity, andultimately soil fertility.

The advantages and disadvantages of the principal methods of sludge treatment discussedabove are listed in Table 7.

T ABLE 7. C OMPARISON OF SLUDGE STABILISATION M ETHODS 5 P ROCESS ADVANTAGES D ISADVANTAGES

AnaerobicDigestion

Good destruction of volatile solids and pathogens.Use of methane gas can reduce net costs.

Widely applicable.Product suitable for agricultural use.Reduces raw sludge volume.Low energy requirements.

Requires skilled operators.May give rise to foaming.Methane production is slow, and may cause

interruption from which recovery is slow.Scum and grit may be difficult to clean.May generate odour.High capital cost.Potential for mineral deposition.

AerobicDigestion

Low initial cost for small plants.Ease of operational.Widely applicable.May not generate odour.Reduces raw sludge volume.

High energy costs.Generally lower volatile solids destruction.Reduces pH and alkalinityPathogens may spread through aerosol drift.Sludge is often difficult to dewater.Performance adversely effected by coldtemperatures.

Composting

Low initial cost.High quality end product suitable foragricultural use.May be combined with other processes

May require a substantial area of land.Requires sludge with 40-60% solids.Requires a carbon bulking agent.Pathogens may be spread through dust.High operational cost.Potential for odour.Generates leachate.

LimeStabilisation

Low capital cost.Ease of operation.Good for emergency operations.

End product may be of limited use in agriculture.Chemical intensive.Cost is site-specific.Results in an increase in sludge volume.The pH drop after treatment may result in odourand biological re-growth.

Source: Adapted from WPCF (1985)

5 Water Pollution Control Federation (1985), Sludge Stabilization, Manual of Practice FD-9 FacilitiesDevelopment, prepared by Task Force on Sludge Stabilization.


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sites will be investigated before, for example, a farmer buys sludge to improve his soil or alandscaper designs a public park intended to take treated sludge.Rates of ApplicationAn approximate guide to the quantities of sludge that may be satisfactorily applied to the landis given in Table 8.

T ABLE 8. SLUDGE APPLICATIONS FOR DIFFERENT T YPES OF L AND 7 R ATES OF APPLICATION (tonnes/ha, dry wieght )T YPE OF LAND F REQUENCY

R ANGE AVERAGE Agricultural 1-2 times each year 2-70 10 Afforested Annually or at 3-5 year intervals 10-220 18 Reclamation Sites One time only 7-450 112

Geographical ConstraintsSludge cannot be safely applied to steep slopes, to areas where it is likely to contaminatewater resources or other particular features of the landscape. The limitations on theapplication of sludge imposed by slope is summarised in Table 9.

T ABLE 9. R ECOMMENDED SLOPE L IMITATIONS SLUDGE APPLICATION 14 SLOPE SUITABILITY

0-3% Ideal, with no concern for runoff or erosion of liquid or dewatered sludge. 3-6% Suitable for the application of liquid and dewatered sludge with some risk of erosion.

6-12% Liquid sludge must be injected into the soil except in closed drainage basins or areaswith runoff control. Usually suitable for dewatered sludge.

12-15% Unsuitable for liquid sludge application without effective runoff control. Suitable fordewatered sludge with immediate incorporation into the soil.

Over 15% Generally unsuitable for the application of liquid or dewatered sludge. Approval may begiven where the steep slop is short and/or is a minor part of the total application area.

Areas which are inherently unsuitable for sludge application include the following:

Areas adjacent to rivers, streams and lakes, including floodplains, wetlands and marshes, andother areas where sludge may enter the aquatic environment;Areas underlain by karst or heavily fractured bedrock, with steep and sharp relief, or with a thinor rocky soil cover, where leachate may infiltrate to groundwater without natural filtration; Areas adjacent to Natural Reserves, historical, cultural or archaeological sites, or other protectedlands;Areas adjacent to the sea and foreshore, where sludge might enter the marine environment;Areas to which the public have unrestricted access

Rock and soil permeability allows leachate and fine particles to infiltrate into the underlyinggeological strata, possibly causing contamination of shallow groundwater. The best sites forthe application of sludge are therefore underlain by low permeability soils and rocks and withgroundwater found at substantial depth. Sludge should not be applied in areas that contributerecharge to major aquifers.Climatic ConstraintsSeasonal variation in rainfall, temperature, wind and other climatic factors are importantconsiderations in sludge application. Heavy rainfall may generate leachate and erosion, hightemperatures increase soil salinity, and high winds may lift dried sludge and cause dust. Agricultural Constraints:It is necessary to coordinate the timing of sludge applications with planting, grazing orharvesting. Under European regulations, no grazing is permitted for three weeks after treatedsludge has been applied to grassland and the sludge must be injected into the soil instead ofspread on the surface. Treated sludge can only be applied to cereal crops, turf, but not for 3

7 U.S. EPA (1995), Land Application of Biosolids, Office of Research & Development , National RiskManagement Research Laboratory, Centre for Environmental Research Information, Cincinnati, Ohio.


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months before harvesting, and fruit trees, but not 10 months before harvesting. Untreatedsewage can only be ploughed in or injected into the soil prior to planting.For efficient agronomy, the most cost effective application provides the amount of nitrogenneeded by the crop, with little left to pass below the root zone, where it is no longer availableto the plants and may contaminate groundwater. Samples of both the soil and sludge need to

be analysed to define any soil deficiencies and identify the benefits sludge application willimpart. A list of Lebanese laboratories capable of undertaking wastewater, sludge and soilanalyses are given in Appendix 2. The determinations of particular relevance to theapplication of treated sludge to the land are nitrate, in which plants take up nitrogen; thecarbon-nitrogen ratio, which indicates the soils potential to mobilise the nitrogen in thesludge; plant-available potassium and phosphorous, and pH to indicate the accessibility of soilnutrients and the immobilisation of trace elements.

Monitoring Sludge Application.The monitoring of sludge application is required to ensure there is no adverse effect uponhealth and safety, the environment. The recommended frequency of monitoring chemical and

bacteriological pollutants, vector attraction, and other criteria varies with the intensity ofapplication, as shown in Table 10.

T ABLE 10. M ONITORING OF SLUDGE APPLICATION 8 AMOUNT OF SLUDGE APPLIED (tonnes)

P ER 365- DAY PERIOD P ER DAY F REQUENCY OFM ONITORING

0-290290-1,500

1,500-15,000Over 15,000

0-0.850.85-4.54.5-45

Over 45

AnnuallyQuarterly

Every 60 daysMonthly

U.S. regulations for sewage sludge application require both the sludge content and the loading

rate of 10 trace metals, which pose both environmental and health risks, to be monitored. Thelimits on these metals are given in Table 11. Sludge with concentrations above the ceilinglevels are prohibited for land application.

T ABLE 11. US STANDARDS FOR T RACE M ETALS IN SLUDGE APPLIED TO THE L AND 9

T RACE M ETAL

C EILING C ONCENTRATION

(mg/kg) a,b

T RACE M ETAL

M AXIMUMALLOWABLE

C ONCENTRATION (mg/kg) a,b

ArsenicCadmiumChromiumCopperLead

7585

3,0004,300840

MercuryMolybdenum

NickelSeleniumZinc

5775

420100

7,500a Dry-weight basis.

b All samples must meet the ceiling concentrations to be eligible for land application.

U.S. standards also requires sludge for land application to have a bacterial quality of less than1000 faecal coliforms/gm of solids and less than 3 salmonella sp./4 gm of solids. Inadequatelytreated sludge is attractive to vectors (insects, rodents and birds) when applied to the land.

8 U.S. EPA (1995), Land Application of Biosolids, Office of Research & Development, National RiskManagement Research Laboratory, Centre for Environmental Research Information, Cincinnati, Ohio.

9 Adapted from Part 503 CFR, reference: U.S. EPA, Land Application of Biosolids, Office of Research &Development, National Risk Management Research Laboratory, Centre for Environmental ResearchInformation, Cincinnati, Ohio.


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8. E NVIRONMENTAL IMPACT ASSESSMENT All proposals for new wastewater treatment plants in Lebanon require an EnvironmentalImpact Assessment (EIA) before they are approved for construction. The EIA is part of the

planning and permitting procedure, used to identify significant environmental impacts thatmay accrue from the intended development, and establishes an Environmental ManagementPlan (EMP) for mitigating potential negative impacts.

EIAs are used to achieve the following:

Improve the design of a proposal;Ensure that resources are used efficiently;Enhance the socio-economic aspects;Identify measures for managing impacts;Facilitate informed decision-making;Provide justification for a proposal;Compare alternative technologies;Involve the public in decision-making.

The stages in the Environmental Impact Assessment process are shown in Table 12 andillustrated in Figure 2. Typical Terms of Reference for the Environmental Impact Assessmentof a typical municipal wastewater treatment plant in Lebanon is given in Annex Three.

T ABLE 12. T HE EIA P ROCESS C OMPONENT D ESCRIPTION

SCREENING An Initial Environmental Assessment (IEE) is submitted by the Municipality to theMinistry of Environment, who screen it to decide if the project requires a full EIA.

SCOPING From the likely key impacts identified in the IEE and the Terms of Reference for theEIA study is prepared.

ASSESSMENT

The EIA study is undertaken by the Municipality, usually through the appointment

of an Environmental Consultant. All potential environmental impacts are identified,analysed and evaluated.

MITIGATION Within the EIA study, an Environmental Management Plan (EMP) is prepared todefine the measures that will be undertaken to prevent, reduce or compensate foreach potential impact and to minimise environmental damage.

REPORTING The results of the EIA study are submitted to the Ministry in an internationallyaccepted format

R EVIEW The Ministry assess the EIA report and, taking account of the views of Stakeholders,determine the acceptability of the proposed project with regard to existing policy,

plans and regulations.

DECISION The Ministry decides if the project should be approved. It has the option to approvea project subject to design modifications to minimise environmental impact.

MANAGEMENT ANDMONITORING

After the project is approved and construction commences, the implementation ofimpact mitigation and other provisions of the EMP are monitored and any necessaryremedial action undertaken. Responsibility for the management of EMPimplementation rests with the Municipality, who will generally appoint the Engineersupervising construction to fulfil the necessary duties.

PUBLIC I NVOLVEMENT Primarily during the early stages of the EIA process, but possible at any stage,

public involvement may be required, This may range from the dissemination ofinformation about the project, to public involvement in the decision-making process.


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F IGURE 2. T HE EIA P ROCESS 10

10Ministry of Environment, Lebanon (July 25, 2001 ), Draft EIA decree


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9. THE S ELECTION OF WASTEWATER TREATMENT

The selection of a wastewater treatment system is not simple. As has been demonstrated in the previous chapters, there are many processes to choose from, each with their own technical andeconomic advantages and disadvantages. This chapter of the Guidance Manual attempts to

steer the user through the selection process, to ensure all the various considerations are takeninto account.

When the options have been reduced to a shortlist, municipalities without in-house expertiseoften find it preferable to retain a specialised Wastewater Treatment consultant to completethe assessment and recommendations for a particular project. Wastewater equipment suppliersare also ready to assist a potential purchaser with selection and plant design, but they may beless than impartial and tend to recommend the equipment of manufacturers they represent.

9.1. F ROM C ONCEPT TO C ONSTRUCTION

The most important element in any decision-making understands the problem. For wastewater

treatment, this primarily requires knowledge of the population to be served, the character ofthe collection network, the quantity and quality of wastewater to be treated, the selection of asite that will afford both efficient operation and minimal environmental impact, and thedisposal of both the treated effluent and the sludge. Most municipalities have a goodunderstanding of the areas for which they are responsible and much of this information will

be readily available. It is beneficial to document such information in a logical manner and theData Sheet given in Annex Four may be used for this purpose.

The selection of a suitable site for a new wastewater treatment plant is often surprisinglysimple. A municipality with an existing collection network draining by gravity to an existingoutfall will usually prefer to treat the wastewater in the vicinity of the outfall rather than incur

the cost of installing a collection tank and pumping raw sewage to a distant site. Even wherenetworks are being extended or new ones being built, the preference will be for gravitydrainage to a low point. The search for a suitable site should therefore first investigate the area

below the town or village to be served, at an adequate distance to allow for planned orforeseen future expansion of the community and its collection network.

With the scope of the project largely determined and a potentially suitable site (or sites) forthe plant identified, the preferred treatment process can be determined. Again, decision-making is subject to a wide range of variables and different parameters will need to be givendifferent priorities by different municipalities. The decision trees given in Tables 13-16 may

provide useful guidance, but they cannot cover all eventualities and local conditions and

requirements may deviate the user from following them explicitly.Prior to making the final decision on the type of treatment process, the disposal of sludge andeffluent must be considered, as this will influence the final choice, particularly of any tertiarytreatment. Small municipalities with only a few hundred cubic metres a day of effluent, andsludge removal 2 or 3 times a year, might well consider the development of municipalgardens to provide for the disposal of both, at the same time enhancing the community for the

benefit of both residents and visitors. Play or other areas where the public may come intodirect contact with the ground are best excluded from such developments, or at least closedfor a few days during effluent irrigation and/or sludge application. Highway centralreservations, roundabouts, street trees and municipal flowerbeds are ideas receptors of

appropriately treated effluent during the summer months, but alternative arrangements willneed to be made during the winter when the ground is naturally sodden. Provision for thedisposal of effluent and sludge may also be made with local farmers, perhaps at somefinancial advantage to the municipality. It may be assumed that wastewater effluent of a


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quality suitable for irrigation will also be suitable for discharge into a watercourse during thewinter months, although this will need to be verified during detailed planning. Treated sludgegenerated during the winter months can be stored for summer application to the land, butstock piles will need to be covered to prevent odour and bacterial re-growth.

Once the preferred treatment process and viable effluent/sludge disposal policies have beenformulated, the Environmental Impact Assessment can be prepared. Since this will look indetail at the wastewater to be treated, the site, the treatment options and the final disposal orre-use of the sludge and effluent, it is better to undertake this before final design of the projectis put in hand. The EIA study, particularly where the services of an Environmental Consultantare retained, will uncover aspects not previously considered and assign different priorities tothose that were. The review of the EIA report by the Ministry of Environment, whoseexperience is countrywide, may also prove useful to the municipality in its final decision-making.

Once the EIA has been approved by the Ministry and the final decisions taken, a tender forthe design of the treatment plant and the supervision of construction can be let. In due course,a contractor is appointed and the plant commissioned to provide the community with a safeand sustainable solution to their wastewater disposal problems.

In summary, the process for the selection of a treatment plant is as follows:Data collection.(See Annex Four)

Select a suitable site or sites for further consideration.(See Chapter 9 above)

Consider the various options for wastewater treatment with those for disposal and/or re-use.(See Chapters 2-7 above and Tables 13-17 below)

Undertake, or appoint an Environmental Consultant to undertake, the EIA study.(See Chapter 8 above and Annex Three)

Appoint a Design and Supervision of Construction Consultant, if not done in-house(See Chapter 9 above)

Let a tender for the construction of the treatment plant

Monitor contract progress and the implementation of the EMP(See Chapter 8 above)

Commission the treatment plant

Undertake capacity building and operational monitoring in accordance with the EMP.(See Chapter 8 above)


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T ABLE 13. DECISION T REE FOR THE T REATMENT OF R AW W ASTEWATER

Does the wastewater collection network to the Treatment Plant comprise only buried foul sewer pipelines?

No Yes

Install a bar rack forPreliminary Treatment

Install screens for preliminary treatment

Install primary settlement

tank

Are costconsiderations

paramount?

Is the land take for the

treatment plant a primaryconcern?

Yes No

Is the available landgenerally level? No

Yes

Are costconsiderations

paramount?

No Yes

Yes No

Considerusing FixedFilm Systemsfor SecondaryTreatment

ConsiderusingActivatedSludge forSecondaryTreatment

Considerusing Aerated

Lagoons forSecondaryTreatment

Considerusing Waste

StabilisationPonds forSecondaryTreatment


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T ABLE 14. DECISION T REE FOR THE T ERTIARY T REATMENT OF E FFLUENT

Is the cost of treatmentrecoverable from thefees paid by irrigators?

Is the Treated Effluent to be re-used?

No Yes

Discharged to aregional collectorsewer

Yes

No further treatment

For potablewater orshallowgroundwaterrecharge

For use as processwater inindustry

For Irrigation

Additionaltreatment isnecessary.Consult awastewatertreatmentSpecialist

Additional

treatmentmay benecessarydependingon theneeds ofthe process

Will it be dischargedto the sea or awatercourse?

No

Is the controlof residual

chlorine aconcern?

Yes No

Utilise UV orOzoneDisinfection

Utilise ChlorineDisinfectionwith chlorineresidue control

No Yes

Utilise UV orOzoneDisinfection

Utilise ChlorineDisinfection with chlorineresidue control

Does the biologicalquality of the effluentmeet the required MoEStandard

Yes No

No further treatment


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T ABLE 15. DECISION T REE FOR THE T ERTIARY T REATMENT OF SLUDGE

No

Is the Sludge to be re-used?

Yes

For soilimprovement

Other re-use

Landfill Incineration Other

How will it be disposed of?

Discuss withMoE before

progressing further plans

Discuss with MoE before progressingfurther plans

Discuss therequirementsfor sludgemoisturecontent with theincineratoroperator beforedeciding onsludgetreatment

Discuss therequirementsfor sludgemoisturecontent with thelandfill operator

before decidingon sludgetreatment

Is the product to besold commercially?

Will it be applied tolime-rich soils?

Stabilisesludge byanaerobicdigestion or

com ostin

Stabilise sludge by composting

Yes No

Yes No

Stabilise sludgewith lime


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T ABLE 16. DECISION T REE FOR THE R E -U SE OF E FFLUENT AND SLUDGE FOR AGRICULTURE

Is the effluent quality suitable for irrigation?

Yes No

Select an improvedtreatment process oralternative methodof disposal

Has the soil been tested, forat least pH, salinity, nitrogen,

potassium, phosphorus,sodium and chloride?

No Yes

Collect a soilsample andhave itanalysed

Consult an Agronomist or Wastewaterirrigation Specialist


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ANNEXES

ANNEX ONE. E NVIRONMENTAL L IMIT VALUES FOR W ASTEWATER D ISCHARGE .

LEBANESE S TANDARDS 11

P ARAMETER T HE SEA SURFACE W ATERCOURSES 3 SEWERAGESYSTEMS

pH 6-9 6-9 6-9Temperature C 35 30 35BOD mg O 2/l 25 25 125COD mg O 2/l 125 125 500Total Phosphorus mg/l 10 10 10Total Nitrogen mg/l 1 30 30 60Suspended Solids mg/l 60 60 600AOX 5 5 5

Detergents mg/l 3 3 No ELVColiform Bacteria 37C in 100ml 2 2000 2000 No ELVSalmonellae Absence Absence AbsenceHydrocarbons mg/l 20 20 20Phenol index mg/l 0.3 0.3 5Oil and Grease mg/l 30 30 50Total Organic Carbon mg/l 75 75 750Ammonia mg/l 10 10 -Silver mg/l 0.1 0.1 0.1Aluminum mg/l 10 10 10Arsenic mg/l 0.1 0.1 0.1Barium mg/l 2 2 2

Cadmium mg/l 0.2 0.2 0.2Cobalt mg/l 0.5 0.5 1Chromium total mg/l 2 2 2Hexavalent Chromium mg/l 0.2 0.2 0.2Copper total mg/l 1.5 0.5 1Iron total mg/l 5 5 5Mercury total mg/l 0.05 0.05 0.05Manganese mg/l 1 1 1

Nickel total mg/l 0.5 0.5 2Lead total mg/l 0.5 0.5 1Antimony mg/l 0.3 0.3 0.3Tin total mg/l 2 2 2Zinc total mg/l 5 5 10Active Chlorine mg/l 1 1 No ELVCyanides mg/l 0.1 0.1 1Fluoride mg/l 25 25 15

Nitrate mg/l 90 90 No ELVPhosphate mg/l 5 5 No ELVSulphate mg/l 1000 1000 1000Sulphide mg/l 1 1 1

1 Sum of Kjeldahl-N (organic N + NH 3), NO 3-N, NO 2-N2 For discharges in the vicinity of bathing waters a more stringent standard amy be necessary.3 The ELVs are for discharge into a surface water flow of not less than 0.1 l/sec.

11 Decision 8/1, National Standards for Environmental Quality, Ministry of Environment, 30 January 2001.


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S YRIAN S TANDARDS 12

P ARAMETER SEAS O N L AND 1 R IVERS AGRICULTURAL

DRAINAGEC ANALS

Colour No Colour No Colour No Colour No Colour

PH 6-9 6-9 6-9 6-9

Temperature C10>average

temp ofrecipient

5> average temp of recipient

BOD mg/l 60 20 40 60COD (Dichromate) mg/l 200 30 150 100Oil and Grease mg/l 15 10 10 10Total Suspended Solids mg/l 60 30 30 60Total Dissolved Solids mg/l - 800 1200 1000Settleable Solids ml/l - - - -PO4 mg/l 10 1 15 10

NH 3-N-(Ammonia) mg/l 10 5 5 0.5 NO

3-N-(Nitrate) mg/l 50 30 50 40

Total Recoverable Phenol mg/l 0.5 0.01 0.02 0.5Fluorides mg/l 1 0.5 1.5 0.5Sulphide-S mg/l 1 1 1 1Residual Chlorine mg/l - 1 1 -Surfactants mg/l 2 0.05 0.05 0.5Dissolved Oxygen mg/l 4 4 4 4Hydrocarbons mg/l 15 5 5 -5Floating Matter No Floating MatterAluminum mg/l 3 1 1 3Cadmium mg/l 0.2 0.2 0.2Arsenic mg/l 0.1 0.1 0.1 0.1Barium mg/l 2 - 1 -Beryllium mg/l 0.05 0.05 0.05 0.05Cadmium mg/l 0.05 0.01 0.05 0.05Cyanides mg/l 0.15 0.1 0.1 0.05Chromium mg/l 0.5 0.5 0.5 0.5Chromium VI mg/l 0.5 0.05 0.05 0.05

Nickel mg/l 0.5 0.3 0.3 0.5Mercury mg/l 0.005 0.005 0.005 0.005Iron mg/l 2 1 2 2Antimony mg/l 1 0.3 0.3 0.3Copper mg/l 1.5 1 1 1Manganese mg/l 1 0.5 0.5 0.5Zinc mg/l 2 1 2 2

Lead mg/l 0.5 0.2 0.2 0.5Silver mg/l 0.1 0.05 0.05 -Total Value for the Heavy Metals 2 mg/l 2 1 1 2

Total Count of the Colon Group(total bacterial count per 100 ml) 5000 2500 100 5000

1: Areas with possibility of infiltration to underground water2: Heavy metals include: mercury, lead, cadmium, beryllium, chromium, nickel, zinc, and copper.

12 Decision 3207/1, The Maximum Limits of Pollution Parameters for Discharge in the Water Environment,Higher Council for Environmental Safety, 13 May 2002.


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ANNEX TWO. W ASTEWATER TESTING LABORATORIES IN LEBANON

The laboratories listed in Table A2-1 are known by the Ministry of Environment to undertakethe analysis of wastewater. The parameters listed in Table A2-2 are the Environmental LimitValues required under the provisions of Decision 8/1, National Standards for Environmental

Quality, Ministry of Environment, Lebanon, dated 30 January 2001.

T ABLE A2-1. ACCREDITED T ESTING L ABORATORIES L ABORATORY C ONTACT T ELEPHONE F AX L OCATION

Advanced Construction TechnologyServices (ACTS)

Mr. Rabih Faquih 01- 753100 01-737222 Beirut,Lebanon

Environmental Core Laboratory, AmericanUniversity of Beirut (AUB)

Ms.Carol SokhnMs.Asma Bazzi

01-3500000Ext: 4858 or 5204

01-370845 HamraBeirut-Lebanon

Environmental Engineering ResearchCenter- Department of Civil &Environmental EngineeringAmerican University of Beirut (AUB)

Dr. Moatasem ElFadel

01-340460Ext: 3500/1/2

Hamra,Beirut,Lebanon

Industrial Research Institute (IRI) Mrs. Nadia Khoury 01-364983 01-366509 Ras Beirut,Lebanon

Laboratoire de Toxicologie,Hopital St. Joseph

Prof. Abed El AzizGeahchan

01-248750/1/2 01-20325401-248750

Dora,Lebanon

Lebanese American University (LAU) Dr. Jean Chatila 09-54725409-547262

09-944581 Byblos,Lebanon

Public Health Laboratory,(Central Laboratory),Ministry of Health

Dr. Vanda Barakett 01-810491 01-810492 Nsouli Street,Beirut,Lebanon

Centre Regional de l Eau et delEnvironment (CREEN),Faculte dIngenierie ESIB,Universite Saint-Joseph

Dr. Job 01-680513/6 MansouriehEl Metn,Lebanon


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T ABLE A2-2. C URRENT C APABILITY FOR W ASTEWATER ANALYSIS

P ARAMETER ACTS CENTRAL

L AB ECLAUB

EERCAUB

IRI LAB . DE

T OXICOLOGY LAU S

AINT J OSEPH

P RICEG UIDE

PH $5-$10Temperature - $5-$10BOD mg O 2/l - - $20-$35

COD mg O 2/l - $20-$50Phosphorus mg P/l - - - $25-$35

Nitrogen mgN/l 1 - $20-$35Suspended Solidsmg/l

- $10-$20

AOX - - - - - - -Detergents mg/l - - - - - $25-$35Coliform Bacteria37C in 100ml 2

- $10-$30

Salmonellae - $20-$30Hydrocarbons mg/l - - - -Phenol index mg/l - - - x $15-$35Oil and Grease mg/l - - - - $25-$35Total OrganicCarbon mg/l

- - - $5-$10

Ammonia mg/l $5-$40Silver mg/l - - - - $20-$75Aluminum mg/l - $20-$75Arsenic mg/l - - - - $15-$25Barium mg/l - - - - - $10-$20Cadmium mg/l - - - $10-$20Cobalt mg/l - - - $20-$75Chromium total mg/l - - $20-$75HexavalentChromium mg/l

- - x - $25-$35

Copper total mg/l - $20-$50Iron total mg/l $20-$75Mercury total mg/l - - - - $15-$25Manganese mg/l - - $20-$75

Nickel total mg/l - - - $10-$20Lead total mg/l - - $20-$50Antimony mg/l - - - - $10-$20Tin total mg/l - - - - $10-$20Zinc total mg/l - $20-$75Active Chlorine mg/l - - $10-$35Cyanide mg/l - - - - $5-$10Fluoride mg/l - - $15-$35

Nitrate mg/l -

$5-$35Phosphate mg/l - $5-$35Sulphate mg/l $5-$35Sulphide mg/l - - - - $5-$35

Capabilities and prices are subject to change. The Public Health Laboratory only processesofficial or governmental institute samples free of charge.Most laboratories give discounts for large batches of samples or regular testing. Somelaboratories will also undertake sample collection.


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ANNEX THREE. T YPICAL TERMS OF R EFERENCE FOR THE E NVIRONMENTAL IMPACT ASSESSMENT OF A NEW W ASTEWATER TREATMENT P LANT

1. O BJECTIVES OF E NVIRONMENTAL IMPACT ASSESSMENT

All new wastewater treatment plants in Lebanon require an Environmental Impact Assessment prepared in accordance with the regulations and procedures of the Ministry of Environment. Futurerequirements in Syria may be expected to be similar. It is assumed that municipalities will not have theexpertise and resources to produce undertake the necessary studies and prepare the EIA report in-house. These typical terms of Reference are therefore given as guidance to the Scope of Works of anyEnvironmental Consultant contracted to undertake the work.

The main objectives of Environmental Impact Assessement (EIA) are to:

Describe the site-specific environmental impacts; Describe a detailed site-specific impact mitigation plan, suitable for inclusion in the Technical

Specification of the treatment plant construction contract; Describe a detailed site-specific Environmental Mitigation Plan (EMP);

Describe the resources needed to implement the EMP.

2. F ORMAT FOR THE EIA R EPORT

The EIA report should be concise and limited to the discussion of significant environmental issues.The main text should focus on findings, conclusions and recommended actions, supported bysummaries of the data collected and citations of any references used in its interpretation. Detailedshould be presented as Appendices to the report. Unpublished documents not readily available toreport reviewers should also be included in an Appendix.

The EIA report should be organised with elements similar to the following:

A. E XECUTIVE S UMMARY

A one-page non-technical outline of the report findings, readily understood by non-experts.B. INTRODUCTION This should fully identify the location on the proposed wastewater treatment plant, includingMohafazat, Caza and cadastral plot number, and site owner and/or operator. A location plan at a scaleof 1:20,000 should be included. Background information should include the requirement for the new

plant and a summary of any pollution caused by present wastewater disposal practices.

C. P OLICY , LEGAL AND ADMINISTRATIVE F RAMEWORK The directly relevant legal framework applicable to the treatment and disposal of wastewater at thespecific project site should be described. A list of directly relevant legislation and a short descriptionof those most relevant will be sufficient. The objective is to ensure the legal framework is fullyidentified so it can be incorporated into the EMP.

D. S UMMARY OF THE P ROPOSED S UB -P ROJECTAn outline description of the community to be served by the new plant, its area, population, and thenumber of beneficiaries. A brief description of existing wastewater collection, facilities fordisinfection and disposal, the age and condition of existing pipework, leakage, and the present quantityand quality of the wastewater. Discuss, with diagrams, the layout of the proposed plant construction,the treatment process to be used, the primary design parameters, any proposed improvement orextension to the collection network, and the proposals for the ultimate disposal or re-use of bothtreated effluent and sludge

E. S IGNIFICANT B ASELINE E NVIRONMENTAL DATA Discussion of the existing environment within the vicinity of the proposed wastewater treatment plant,to include separate sections on:

Topography, geology, soils landscape, and land utilisation, by reference to a 1:20,000 maps; Presence of environmental protection zones and other conservations areas, areas of outstanding

natural beauty, archaeological, cultural or touristic sites;


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Surface drainage channels, perennial and seasonal, and springs; abstractions and discharges, andwater quality;

Ground water aquifers, wells and borehole locations, abstraction rates; use; water quality, groundwater flow, water levels and recharge zones;

Socio-economics, including any employment opportunities generated by the proposed plant.

Public consultation and other consultations undertaken to ensure the meaningful involvement ofStakeholders.

F. S IGNIFICANT E NVIRONMENTAL IMPACTS Identify the primary issues to be addressed. Separately describe potential positive and negativeimpacts, for the latter, separating those that may be temporary, primarily during construction, from anyexpected to be permanent. Make reference to any interviews, field observations and sources oftechnical information used in determining potential impacts.

G. ANALYSIS OF ALTERNATIVE P ROPOSALS FOR THE S UB -PROJECT . Briefly summarise any alternative sites or treatment processes considered during the formulation ofthe project and gives reasons why these were rejected. If there are no alternatives, state that noalternatives were considered.

H. E NVIRONMENTAL MANAGEMENT P LAN The EMP must include separate sections on environmental mitigation, monitoring and any necessarycapacity building for the execution of the Plan.The Environmental Mitigation Plan should detail the measures that will be implemented in order tomitigate the identified negative impacts, and protect against other potential adverse impacts. In

particular, discuss the arrangements for the continued provision wastewater collection and disposalduring periods of disruption, e.g. by over-pumping, and the protection of the environment in thevicinity and downstream of any points of temporary discharge. Where necessary, contractual clausesfor inclusion in the project bidding and construction documents should be developed.The Environmental Monitoring Plan will detail of the municipalitys proposals for monitoring of the

project, to include Compliance monitoring during the period of construction,Environmental Monitoring, e.g. of water level and quality at adjacent sources, andPost-Construction Environmental Monitoring, e.g. of surface, ground water, and air quality toascertain any long-term contamination from the treatment plant.Capacity strengthening for the implementation of the EMP will identify the additional human andfinancial resources necessary and the need for managerial and operator training.

I. APPENDICES Appendices to the EIA report should include preliminary design drawings, site photographs, records ofinter-agency, public and other consultation meetings, environmental data, a list EIA report preparers,and copies of unpublished documents cited in the text.

3. S TAFFING F OR EIA R EPORT P REPARATION AND EMP S UPERVISION

The core team for the preparation of the EIA report and supervision of EMP implementation willusually comprise 2-4 key staff, their specialities to encompass wastewater treatment, infrastructureconstruction, environmental standards and monitoring, hydrology and hydrogeology, and effluentDisposal. The Consultant should name individuals for specified roles, provide detailed curriculumvitae for each, and give an assurance they will be made available as specified in his proposal, if he isawarded the contract.


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ANNEX FOUR. DATASHEET FOR THE S ELECTION OF W ASTEWATER TREATMENT

The following checklist is provided as a guide to the general background information required for theselection of an appropriate wastewater treatment process. It also provides much of the information thatwill be required by an Environmental Impact Assessment Consultant.

N AME OF PROJECT : _________________________________________________________________C AZA : ____________________________ MOHAFAZAT ____________________________________RESPONSIBLE ORGANISATION OR MUNICIPALITY :_____________________________________________N AME AND TELEPHONE NO . OF P RIMARY CONTACTS : _________________________________________DOES THE PROJECT INTERFACE WITH OTHER WORKS ? YES /NO . IF YES , GIVE DETAILS :

_________________________________________________________________________________

AREA DRAINING TO WWTP (IN HA) _______________________________________________________TOTAL REGISTERED P OPULATION TO BE SERVED _____________________________________________

ALLOWANCE FOR SEASONAL VARIATION (%) ________________________________________________NUMBER OF PROPERTIES TO BE SERVED ___________________________________________________

OF WHICH : DOMESTIC ___________________________________________________COMMERCIAL __________________________________________________

INDUSTRIAL __________________________________________________

TOTAL LENGTH OF COLLECTOR NETWORK DRAINING TO WWTP (KM) ______________________________OF WHICH : SUB -SURFACE SEWER PIPELINES (KM) _______________________________

OPEN CHANNEL FOUL SEWERS (KM). ______________________________STORM WATER DRAINAGE PIPELINES (KM) _______________________________

OPEN CHANNEL STROM WATER DRAINS (KM) _______________________________

LIST LARGE DOMESTIC /COMMERCIAL CONTRIBUTORS (EG . SCHOOLS , HOSPITALS , ARMY CAMPS ) ________________________ ______________________ ________________________ ________________________ ______________________ ________________________ ________________________ ______________________ ________________________

LIST TYPE AND NUMBER OF LARGE INDUSTRIAL CONTRIBUTORS (EG . METAL WORKS , TANNERIES , SLAUGHTERHOUSES , FOOD PROCESSING WORKS )

________________________ ______________________ ________________________ ________________________ ______________________ ________________________ ________________________ ______________________ ________________________

G IVE DETAILS OF ANY PRE -TREATMENT OF WASTEWATER PRIOR TO DISCHARGE TO THE PUBLIC SEWER SYSTEM _________________________________________________________________________________ _________________________________________________________________________________LIST SMALL INDUSTRIAL UNITS CONTRIBUTING TOXIC OR HAZARDOUS WASTEWATER WITHOUR PRE -TREATMENT .

________________________ ______________________ ________________________ ________________________ ______________________ ________________________ ________________________ ______________________ ________________________

EXPECTED PER CAPITA CONTRIBUTION (L/H/D) _______ (TYPICALLY 120-150 L/H/D) C ALCULATE PLANT CAPACITY : P OPULATION ________ X PER CAPITA CONTRIBUTION ______ = _______ M3/D

ADD FOR STORM WATER ._______% = _______ M3/D ADD LARGE DOMESTIC /COMMERCIAL CONTRIBUTORS = _______ M3/D

ADD LARGE INDUSTRIAL CONTRIBUTORS = _______ M3/D ADD FOR URBAN EXPANSION OVER 10 YEARS = _______ M3/D

S UB-TOTAL = _______ M3/D LESS 10% FOR INFILTRATION FROM SEWER NETWORK = _______ M3/D

TOTAL P LANT C APACITY REQUIRED = _______ M3/D

HOW AND WHERE IS THE WASTEWATER EFFLUENT TO BE DISPOSED ? ______________________________ _________________________________________________________________________________HOW AND WHERE IS THE SLUDGE TO BE DISPOSED ? __________________________________________

_________________________________________________________________________________IF SLUDGE IS TO USED FOR SOIL CONDITIONING , GIVE AREA (HA), USE OF LAND , AND TYPES OF CROP :

_________________________________________________________________________________


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HAS THERE BEEN MEANINGFUL DISCUSSION WITH STAKEHOLDERS ? YES /NO . IF YES , GIVE DETAILS : _________________________________________________________________________________

P REPARE PLANS OF THE SITE AT AN APPROPRIATE SCALE AND OFTHE AREA WITHIN A RADIUS OF 1KM AT ASCALE OF 1:20,000 CLEARLY SHOWING : EXISTING AND NEW VEHICULAR ACCESS , EXISTING BUILDINGS TO BEDEMOLISHED , PUBLIC BUILDINGS , PRIVATE HOUSING , SITES OF CULTURAL , ARCHAEOLOGICAL OR TOURISTICINTERETS

, AREAS OF NATURAL LANDSCAPE

, FORESHORE AND OTHER PROTECTED AREAS

, WATER SOURCES

SUCH AS SPRINGS AND WELLS AND OTHER SIGNIFICANT FEATURES .

COLLECT A REPRESENTATIVE SAMPLE OF EXISTING WASTEWATER FLOW AND HAVE IT ANALYSED AT AN APPROVED LABORATORY .

RANK IN ORDER OF IMPORTANCE THE FOLLOWING CONSIDERATIONS IN TREATMENT PROCESS SELECTION : CONSISTANTLY HIGH THROUGHPUT , ABILITY TO COPE WITH VARIABLE THROUGHPUTS , LOW VISUAL IMPACT , LOWODOUR , OPERATED BY UNSKILLLED LABOUR , WASTEWATER RE -USE AND SLUDGE RE -USE

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