ENGG1006 - Engineering for Sustainable Development

RESOURCE AND WASTE MANAGEMENTDr. Kaimin ShihDEPARTMENT OF CIVIL ENGINEERING THE UNIVERSITY OF HONG KONG

Office: Rm. 5-26, Haking Wong Building Phone: 2859-1973 E-mail: kshih@hku.hk

PROGRESS & OUTCOMES

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Resource Consumption and Prediction

Sustainable Development is: A pattern of resource use that aims to meet human needs without compromising the ability of future generations to meet their own needs. Resource: A source of supply or support

.

Natural Resources

Renewable ResourcesCan be reproduced easily, such as sunlight, wind, crops, fish,

Non-Renewable Resources NonFormed over very long geological time, such as oil, coal, minerals,

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Accumulative Discovery and Extraction of Copper

Growth of Global Metal Extraction Rates

E = E0e-ktCurrent extraction rate Initial extraction rate

Current time

Growth of extraction rate

td is the doubling time, when E = 2E0.

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4.2 billion tons/year !

World Reserve: 900 billion tons Constant consumption rate (7 billion tons/year) 132 years Current k = 2.5% 56 yearsCountry China USA India Australia Russia S. Africa Germany Reserve (Billion tons) 114 247 92 79 157 49 6.7 5.0 14 Production (Billion tons/year) 2.38 1.05 0.45 0.37 0.30 0.26 0.20 0.20 0.16 Reserve Life* (Years) 48 235 204 214 523 188 34 25 88

Global Coal Use

Indonesia Poland

* Not considering the growth of production rate.

World Oil ConsumptionIn 1000 barrels per dayTransportation is the largest sector (55% worldwide and 69% in US) and is also the sector with largest growth in recent decades Growth in demand: average 1.76% from 1994-2006

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World Energy Consumption

Energy Crossroads: A Burning Need to Change Course (2007)[2:35]

As fossil fuels power every facet of our economy, how can we avoid an energy crisis and a possible collapse of our economy? This documentary exposes the problems associated with our energy consumption, and features experts and scientists at the forefront of their field bringing legitimacy and expertise to the core message of the piece.

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Reserves vs. Resources

Not recoverable under present technology & economic conditions

Oil Depletion Prediction In 1970, reserves = 550 billion barrels & production = 17 billion barrels per year, should be depleted in 32 years. Well, we are surely still producing oil TODAY ! In 2005, reserves = 1300 billion barrels & production = 30.7 billion barrels per year, depletion in another 42 years !

A do they have is common? What sense of the futurein essentialin influencing many decisions we make today

Johann Adam Schall von Bell

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A local power generation facility: Predict the local population growth rate over next decays A local ecosystem: Predict the growth rate of an endangered species Scientist and policy maker: Estimate deforestation & reforestation rates due to global warming

We cannot expect to make accurate predictions of the future. But, we can use simple mathematic models to develop very useful what if scenarios.

Symmetrical Curve for Resource PredictionAssume resource cycle by M. King Hubbert (1969): Begin with exponential growth of production when the resource is relative abundant and cheap Eventually the high price, due to depletion and likely substitutes, will decline the production precipitously back to close to zero. This production rate cycle resembles a symmetrical and bell-shaped curve, same as the normal (or Gaussian) function used in probability theory.

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Normal (or Gaussian) Distribution

P Pm tm Will be 95% if within 2

= production rate = maximum production rate = time when Pm occurs = standard deviation

exp {} = exponential function

* This part is not within our course learning outcomes.

P = Pm exp { (-1/2) [(t tm) / ]2 }

Management of World Oil ProductionTwo possible scenarios (based on 2000 billion barrels in total): Gaussian curve by historical production record: Oil production will peak just before year 2000 Enforce conservation policy: Supplies will last until year 2040 before the decline

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Generation of Waste

All creatures, humans included, constantly make decisions about what to use and what to throw away

Extract energy from C-C & C-H bonds

Chimpanzee & banana

Paramecium & organic molecules You and your soft drink

Waste is a consequence of material consumption.

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Material ConsumptionFunction of solid materials in society Food Energy (fossil fuels) Buildings and construction Consumer goods, capital goods (machinery, transport equipment)

Life time (retention) of goods Long life: years, e.g. appliances, structures (durables, capital goods) Medium life: weeks, months, e.g. newspaper, shoes, clothes Short life: days, e.g. food, packaging (non-durables, consumer goods)(now - ?)

(1937- )

Definition of Solid WasteSolid waste is any solid material rejected by society because it is unwanted or useless.

It has a significant angle of repose.

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Solid Waste in HistoryWhen humans abandoned nomadic life ~10,000 BC, they began to live in communities, resulting in the production of solid waste. The Indus Valley civilization (started ~6000BC):The city of Harappa (3300-2000BC): had toilets and drains. The city of Mohenjo-daro (2600 -1900BC) had houses with rubbish chutes and probably collection systems.

By 2100BC, cities on the Island of Crete had trunk sewers connecting homes. Sanitary Laws written by Moses in 1600BC By 800BC, Old Jerusalem had sewers and a primitive water supply. By 200BC (Han Dynasty), cities in China had Sanitary Police to enforce waste disposal laws.

In Athens in 500BC, a law was passed to require all waste to be deposited more than 1 mile away from the town

1 mile

away

A T H E N S

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A T H E N S

A T H E N S

But for the most part people in cities lived among waste and squalor. Only when the social discards became dangerous for defense was action taken

In Athens in 500BC, a law was passed to require all waste to be deposited more than 1 mile away from the town. Because the piled rubbish next to city walls helped invaders to scale up and over the walls Rome had similar problem and eventually developed a waste collection program in 1400AD. Cities in the Middle Ages in Europe unimaginable filth (animals roamed the streets; wastewater dumped out windows,..). As a result, the Black Death in 1300AD reduced cities population and alleviate waste problem until mid-1800s.

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England during Industrial Revolution:Working poor (on average one toilet per 200 people in Manchester). Great Sanitary Awakening (1840s) spearheaded by a lawyer Edwin Chadwick, who argued connection between disease and filth. Physician John Snow stop cholera epidemic (1854) by removing pump handle on Board Street in London.

Charles Dickens (1812-70)

Sir Edwin Chadwick (1800-90)

Dr. John Snow (1813-58)

In 1676, Antonie van Leeuwenhoek, a Dutch Microscopist who was the first person to observe bacteria using a microscope, and published his findings in letters to Royal Society of London after 1684. (later commonly known as the Father ofMicrobiology)Antonie van Leeuwenhoek (16321723), the first microbiologist

Identification of disease-causing bacteria of Bacillus anthracis (1877), Tuberculosis bacillus (1882) and Vibrio cholera (1883). In 1881, he urged the sterilization of surgical instruments using heat. (Nobel Prize in Medicine in 1905 due tothe finding of tuberculosis bacillus )Robert Koch (1843-1910), a German physician

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Solid Waste Engineering and Management

Main Engineering ProcessesCollection Volume Reduction Separation (Sorting) Recycling Composting & Digestion Thermal Treatment Final Disposal (Landfill)

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CollectionWaste Management, Inc. A waste management and environmental services company in North America - The largest trucking fleet in the waste industry (22,000 collection/transfer vehicles) - 413 collection operations (network systems), 370 transfer stations, 283 active landfill disposal sites, 17 waste-to-energy plants, 131 recycling plants, 95 beneficial-use landfill gas projects and 6 independent power production plants. - Serving nearly 21 million residential, industrial, municipal and commercial customers

Employees: ~50,000 Revenue (2006): $13.36 billion USD

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Simple Routing Cost AnalysisSolid waste generation, transportation and disposal costs are:

A 1 2

Source Generation (tons/wk) 1 100 2 150 Disposal Site A B

Transportation Cost ($/ton) Site A Site B 5 12 7 5 Cost($/ton) 4 5

Capacity (tons/wk) 50 200

Assume depose X tons of from source 1 to A per week. Assume depose Y tons of from source 2 to A per week.What is the objective function for minimizing disposal cost?

B

[5X+12(100-X)+4X+5(100-X)]+[7Y+5(150-Y)+4Y+5(150-Y)]min = (3200-8X+Y) min ------ cost of source 1 --------- cost of source 2 ---Constraints: X+Y =50 Solved Results: X=50, Y=0. Objective function minimized to $2800/wk Decision: Source 1 - Dispose 50 tons/wk to Site A; 50 tons/wk to Site B Source 2 - Dispose 150 tons/wk to Site B Minimized Total Disposal Cost will be $2800/wk

Routing Cost Analysis8 transportation costs (xijcij), 2 disposal rates (Fi). Minimize objective function:[x11c11+ x21c21+ x31c31+ x41c41+ x12c12+ x22c22+ x32c32+ x42c42+ F1(x11+ x21+ x31+ x41)+ F2(x12+ x22+ x32+ x42)] Subject to the following constraints (site capacity, Bi, and source amount, Wi): x11+ x21+ x31+ x41 B1 x12+ x22+ x32+ x42 B2 x11+ x21+ x31+ x41 = W1 x12+ x22+ x32+ x42 = W2

A 1 2

3

4

xij 0* This part is not within our course learning outcomes.

B

The equations can be solved using any linear programming algorithm. The transportation algorithm is particularly useful for such applications.

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Volume Reduction (at Refuse Transfer Station)Into compactor and compacted

Refuse conveyed by live floor system

Compacted refuse

Container with compacted refuse

(HKEPD, 2005)

Terminology Bulk density: Solids + Water + Porosity (air) Compactible, noncompactible waste fraction Density before and after compaction Compaction decreases: - Vp - some Ww, VwWaterVw, Ww Dw= Ww / Vw 1000kg/m3

Solids

V s, Ws D s= Ws / V s

Porosity

V p , Wp ( 0 ) D p = Wp / V p ( 0 )

Bulk volume (Vbulk) = Vw + Vs + Vp Bulk weight (Wbulk) = Ww + Ws + Wp Ww + Ws Bulk density (Dbulk) = Wbulk / Vbulk = (Ww + Ws) / (Vw + Vs + Vp )

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Separation (Sorting)

Recyclable paper separation

Recyclable electronics separation (from plastic waste)

Recyclables separation at landfill

Trommel screens can sort multiple sizes, and are excellent primary screens for commingled waste. Robust, no wear parts, but requiring more floor space.

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Horizontal Air Knife

FEEDConveyor

r Ai

Light(e.g. plastic, paper)

Medium(e.g. aluminum)

Heavy(e.g. glass, stone)

Fan

Recycling Waste Hierarchy The waste hierarchy refers to the 4 Rs" waste management strategies in order of importance : - Reduction - Reuse - Recycling - Recovery

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Reduction Example: Pay As You Throw (PAYT)USEPA (1920~, 1993~)

A usage pricing model for disposing of waste, sometimes referred to as unit pricing or variable rate pricing. Users pay a variable rate based on how much waste for collection Recyclable waste is usually collected free of charge Implementation models: containers, binbags, waste stickers, prepaid packaging (refunded & non-refunded)

Pros: Incentive for waste reduction / recycling

Cons: Encourage illegal disposal

Example: Process of Paper recycling

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Metal (aluminium, steel) cans recycling Steel (iron, tin)- Recycling by magnetic separation and melting - Can accept both steel or aluminium cans (due to magnetic separation process) - Save energy (m.p. of metal: 1538oC; of oxide ore: 1565-1600oC)

Aluminium- Recycling by shredded into pieces and melted - Accept only aluminium can - Save significant energy (m.p. of metal: 660oC; of oxide ore: ~900oC)

~~ Both Without "Downgrading" Quality ~~

Composting & DigestionPurposes: Reduction and stabilisation of (biodegradable) organic matter by biochemical processes to soil-like matters or gases.

Aerobic process (composting):[Complex Organics] + O2 CO2 + H2O + NO3- + SO4-2 + stabilized products* + heat

Anaerobic process (digestion):[Complex Organics] + heat CO2 + CH4 + H2S + NH4+

* Can be used for fertilizer.

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Sha Ling Livestock Waste Composting Plant (SLCP)

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Collect livestock waste from leak proof bins (provided)

Shredded wooden pallets as bulking agents

Mixing of wooden pallets and waste (Height: ~2.5m)

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Compost at fermentation boxes (blowing air, ~ 6-8 weeks) (HKEPD, 2005)

Compost at Maturation Shed

The DRANCO (Anaerobic Digestion) Process Owner: Organic Waste Systems (Belgium) Digester loading: 10 to 20 kg carbon/m-reactor per day Temperature range: - Thermophilic: 48 - 57C - Mesophilic: 35 - 40C Retention time in the digester: 15 to 30 days Biogas production: 100 to 200 Nm of biogas per ton of waste* Electricity production: 220 to 440 kWh per ton of waste* N means normal temperature (20oC) and pressure (1 atm) condition.

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Sewage sludge decomposed in 35oC anaerobic digester at Glenwood Springs, Colorado (USA) . The digester is heated by methane, one of the bi-products of anaerobic digester. UC Davis (California, USA) experimental anaerobic digester processes 8 tons of food scraps weekly for energy

Thermal Treatment

(HKEPD, A policy framework for the management of municipal solid waste (2005-2014), 2005)

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Moving Grate Incinerator

Moving Grate System

Stoichiometry (simplified for combustibles)Ca(H2O)mHbClcFdSeNf + [ a + b/4 - (c+d)/2 + e + f/2 ] O2

a CO2 + [ (b-c-d)/2 + m ] H2O + c HCl + d HF + e SO2 + f NO

Note:- HCl, HF, SO2, and NO are air pollutants - Combustion may be incomplete - Additional reactions may take place, volatilization, dust formation, etc.

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Dioxin A combination of many members of an organic compound family Polychlorinated Dibezodioxins (PCDDs). Dioxin occurs as an contaminant in organic (chlorinated) chemicals or a byproduct of combustion. Major emission source in US (1994): Hospital waste combustion (55.4%) and Municipal waste combustion (32.6%). The formation mechanism from combustion is uncertain so far. Used to be assumed by burning chlorinated plastics, recombination formation in cooled flue gas etc., but also with many negative evidences. Extremely toxic to animals, but questionable as expected to humans. Direct measurement in operation is difficult. Hasselriis (1987) proposed: PCDDs = (CO / A)2 , where CO is carbon monoxide and A is a constant subject to operation system.(particularly toxic)

Parent compound of dibenzo-p(or 1,4)-dioxin

2,3,7,8- tetrachlorodibenzo-p-dioxin * Now mostly removed by flue gas filter bag (adsorption) or adsorber columns

Final Disposal (Landfill)

Final disposal at..... Where?[Result]: Not economical

In 1970s, USEPA did feasibility studies of sending wastes to:[Result]: Eventually will come back to earth surface

Two reminding locations: Large bodies of water, such as oceans On or in land

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Landfill in operation

(1) Collection vehicle is weighed at weighbridge on arrival

(2) On the way to the tipping face (3) Waste truck unloads at the tipping face

(5) Vehicle is weighed at weighbridge on departure

(4) Vehicle passes the vehiclewash system after unloading

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Reactor Landfill Feathers Biological and chemical reactions - Anaerobic reactions with gas production - Leachate production causing possible contamination of atmosphere, soil, and groundwater Mass and water balances for prediction of mass/volume changes and leachate generation Velocity and duration of reactions difficult to predict over long-term

Gas generated in landfillTypical constituents of MSW landfill gas Component Methane Carbon dioxide Nitrogen Oxygen Ammonia Hydrogen % by volume 45 - 60 40 - 60 2-5 0.1 - 1.0 0.1 - 1.0 0 - 0.2G a s p ro d u c e d (1 0 6 m 3 )

North East New Territories (NENT) Landfill, Hong Kong4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 1 3 5 7 9 11 13 15 17 19 21 Year since opened

Landfill gas production vs. time

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Ranges of parameters in leachateParameterBOD (mg/L) COD (mg/L) Iron (mg/L) Ammonia (mg/L) Chloride (mg/L) Zinc (mg/L) Total P (mg/L) pH Lead (mg/L) Cadmium (mg/L)

Ehrig 198920-40000 500-60000 3-2100 30-3000 100-5000 0.03-120 0.1-30 4.5-9 0.008-1.020