swm lnotes ii-061

SOLID WASTE MANAGEMENT

LECTURE SLIDESM. Sc. Environmental Engineering

Padma Sunder Joshi

CHAPTER II

SOURCES AND TYPES OF SOLID WASTE

P S JOSHI, IOE Pulchowk Campus 2

Chapter II SOURCES & TYPES OF SOLID WASTE

Waste Generation:

EconomyCultureUrbanity

Generation of waste depends on:

Generation of waste is influenced by:LegislationSource reductionClimatic condition

Units of waste generation:

Residential – kg/c/dIndustrial kg/unit production

Agriculture – kg/ha or kg/animal/d

P S JOSHI, IOE Pulchowk Campus 410 - 85~5 - 35Particle size = 10 mm1 -201 - 301 - 40Miscellaneous inerts

20 - 5020 – 6540 - 85Vegetable/putrescible

2 - 102 – 101 - 5Textiles

~~1 - 5Wood, bones, straw

~~1 - 5Leather, rubber

2 - 102 - 61 - 5Plastics

3 - 131 - 51 - 5Metals

4 - 101 -101 – 10Glass, ceramics

15 - 4015 - 401 – 10Paper

Ranges of compositions20 - 3040 - 6040 - 80Moisture content (% by wet weight)

100 - 170170 - 330250 - 500Waste densities (wet weight basis- kg/m3)

0.7 - 1.80.5 - 0.90.4 - 0.6Waste generation (kg/c/d)

High income countries

>$3500

Middle income countries per capita

$360><$3500

Low income countries per

capita<360

for lower, middle, and higher income countries (Source: Cointreau 1982)

Patterns of Municipal Refuse Quantities and CharacteristicsChapter II SOURCES & TYPES OF SOLID WASTE


100100100100100100100100100100100100100TOTAL78829673856579664037703826Compostible total

42240243221910313221154Miscellaneous inerts

368056498243605695505822Food and putrescible

2218427153521346063295774Non-food total

51124-------4Wood, bones, straw

431517-4109-24Textiles

--17---------Leather, rubber

14-234-5664210Plastics

13144541233813Metals

86131232101489Glass, ceramics

321421714223243183735Paper

Calcutta Indi

a

Lucknow

India

Karachi

Pakistan

Lahore

Pakistan

Jakarta

Indonesi

a

Manila

Philippin

es

Lagos

Nigeria

Medelin

Colombia

Hongkon

g

Singapor

e

Rome

Italy

London UK

Brooklyn USA

Type of waste

Low IncomeMiddle IncomeHigh Income

(in percentage by weight) Source: Cointreau, 1982

Urban Refuse Composition DataChapter II SOURCES & TYPES OF SOLID WASTE


Lecture II SOURCES & TYPES OF SOLID WASTE


Solid Waste Composition in Kathmandu

Organic materials(69.84%)Plastics (9.17%)

Paper (8.50%)

Construction and otherwaste (4.79%)Textiles (3.02%)

Glass (2.50%)

Metals (0.92%)

Rubber & leather(0.66%)Wood (0.60%)


Source: KVMP 2001



Types of Solid Waste

Based on regulatory definition

By source or generatorBy component composition

ResidentialCommercial

Institutional

Construction and demolition

Municipal services

Industrial

Agricultural

Municipal Waste

By source or generator



Residential Waste:

Commercial Waste: Wastes from office buildings, market places, shops, restaurants, hotels, etc.Predominantly – paper, plastics, textiles, food wastes

Various types of wastes generated in residential areas like kitchen waste, waste materials like used newspapers, gift wrappers, broken utensils and equipments, etc.

Residential buildings include houses, flat, apartment blocks

Institutional: Wastes generated from institutions like offices, schools and colleges, etc.These are basically inorganic wastes predominantly papers

……………..Types of solid waste


Municipal service waste: Street sweeping,Wastes from municipal facilities like sludge from waste water treatment facility, incinerators, etc.

Construction and demolition waste:

Waste generated from new constructionDemolition of old structuresSand, dirt, brick bats, aggregates, cement bags, metal scraps, wood and timber, glasses, etc.Dominantly inert, recyclable and can be used for reclaiming land or as a cover to the landfill

Components of construction like paints, treated woods, etc. may demand attention as these contain hazardous materials




Industrial Waste: Non hazardous waste – produced during fabrication, refinery and transformation into consumablesHazardous waste

Agricultural Waste: Wastes generated from harvesting, processing and storing of agricultural productsMost of the wastes are organic and recyclable wastes






By component composition

Food wastes

Paper

Cardboards

Plastics

Textiles, leather, rubber

Glasses

Tins/cans, ferrous and non ferrous materials

Special wastes




Plastics

High density polyethelene (HDPE/2)

Polyvinyl Chloride (PVC/3)

Low density polyethlene (LDPE/4)

Polyethelene terephthalate (PETE/1)

Soft drink bottles, salad dressing and vegetable oil bottles, photographic film

Milk jugs, water containers, detergent and cooking oil bottles

Home landscaping irrigation piping, some food packaging, and bottles

Thin-film packaging and wraps, dry cleaning film bags, other film materials




Polypropylene (PP/5)

Polystyrene (PS/6)

Other multilayered plastic materials

Closures and labels for bottles and containers, battery casings, bread and cheese wraps, cereal box liners

Packaging for electronic and electrical components, foam cups, fast food containers, tableware and microwave plates

Multilayered packaging, ketchup and mustard bottles, various combinations of above products



Special wastes:Bulky items:

furniture

large items

Consumer electronics:

radio, television, stereo, camera, computer etc.

White goods:

cooking stove, washing machine, refrigerators, etc.





Hazardous wasteAny waste or combination of wastes which pose a substantial presence

or potential hazard to human health or living organism because they are lethal, non-degradable, can be biologically magnified or otherwise cause or tend to cause detrimental cumulative effects.

Sources of hazardous waste:Explosivity: mining, oil refinery, etc. Corrosivity: acids from tanning industries, heavy metal industries Inflammability: oil sludge, solvents, etc. Toxicity: chemical industries, pesticides, plastic, fertilizers, etc.

Hazardous waste defined Medical waste defined

Solid waste as defined by the regulation

By component composition

Carcinogenicity: waste which can cause cancer with elongated exposure

Infectious: hospital waste, especially clinical waste




Medical Waste: Clinical and non-clinical wastes

Clinical waste:Pathological waste: limbs, organs, blood, tissuesInfectious waste: solid surgical dressing (all materials in contact with infectious diseases)Sharps: needles, syringes, nails, blades, glassesPharmaceutical wastes: all pharmaceutical products, drugs, chemicals etc.Chemical waste: discarded solid and liquid chemicals from laboratoriesHazardous waste: corrosive (alkaline, acidic)

radioactive waste (X rays)Non-clinical waste: kitchen waste, packaging, etc.

HOUSEHOLD HAZARDOUS WASTEHousehold waste because of its point of generation would be a hazardous waste. It includes used oil, paints, solvents, drain cleaners, pesticides and herbicides.



Properties of Municipal Solid Waste:

Individual components in solid waste

Physical properties:

Particle size

Moisture contentDensity

Field capacity

• Physical properties

• Chemical properties

• Biological properties

Permeability



……………Properties of MSW

Particle SizeImportant for material recovery processFor the design of shredder, screens, etc.Largest dimension and ability to pass the sieve

Size of the component (mm) Sc = (l+w)/2

or = (l*w)1/2

or = (l+w+h)/3

or = (l*w*h)1/3

Individual componentsPaperCardboardPlastics

RubberLeatherWood

Garden trimming/yard waste

Glass Tins/cans

Non ferrous metalsFerrous metalsDirt, ash, bricks



……………Properties of MSWDensity

It is used to determine compacted volumeDetermine volume and weight to be transportedDetermine landfill sizeEvery time waste is handled its density changes

It is location specific: loose, as found in container, compacted, etc.

Density also varies with the length of time it is stored, therefore, collection frequency also effects

Density depends on

Compaction of waste,

Season of the year: humidity, rainfall, wind, etc.



Compaction ratio r = (compacted density ρc/ discarded density ρd)


Density of waste (as discarded basis)

Kathmandu: 600 kg/m3 (Lohani, 1978)

630 ~ 430 kg/m3 (SWMRMC)

250 kg/m3 (KVMP 2001)

India (Poone) 300 kg/m3

USA 128 kg/m3



Moisture ContentImportant for

leachate calculation

Feasibility of incineration

composting


MC may be expressed inWet weight basis

Dry weight basis

MC in wet weight basisMC% = [(w-d)/w] * 100

Where w = initial weight of the sample as delivered, kg

d = weight of the sample after drying at standard temperature (1050c)

MC in MSW of Kathmandu: 39~58% (SWMRMC)

52% (KVMP, 2001)



ΣDMMunicipal solid waste86-12480320-960

Dirt, ashes, brickbats etc.

32-49045-160Tins/cans21-4195160-480Glass

2015-40240120-320Wood

6030-8010560-225Garden trimmings108-1216090-260Leather21-413090-200Rubber106-156530-100Textiles21-46530-130Plastics64-108530-130Paper7050-80290120-480Food wastes

TypicalRangeTypicalRangeDry mass,

kg

Moisture, %Density, kg/m3Mass,

kgComponents*

The moisture content of the total mix isMC = {(ΣM – ΣDM) / ΣM}* 100



Field capacityThis is the capacity of solid waste retaining moisture content against gravity

Important to determine leachate production in landfill

FC varies with the degree of applied pressure and state of decomposition of the waste

FC of commingled MSW is found to be 50~60%

FC in a landfill may be determined by following empirical formula

FC = 0.6 – 0.55 [W/(10000+W)]Here FC = field capacity

W = overburden weight calculated at the mid height of the waste in the lift in question. Unit of W is in lb.




PermeabilityHydraulic conductivity governs the movement of liquid and gases in landfills

Permeability depends on pore size distribution

Surface area

Porosity

Properties of the waste materials

K = C d2 (γ/µ) = k (γ/µ)

K = Coefficient of permeability C = dimensionless constant or shape factor

d = average size of pores γ = specific weight of water

µ = dynamic viscosity of water k = intrinsic permeability




Chemical properties:


This is useful to determine waste processing techniques like waste incineration, composting and heat recovery, etc.

1. Proximate analysis

2. Fusing point of ash

3. Energy content

4. Ultimate analysis

To determine surrogate parameters, especially after/during incinerationThe parameters considered are:

1. Proximate analysis

Moisture: loss of moisture when heated to 1050C for 1 hourVolatile combustible matter: additional loss of weight on ignition at 9500C in covered crucibleFixed carbon: the carbon not burnt after volatile matter is removedAsh: weight of residue after combustion in an open crucible

2015-30Non combustibles75-12Fixed carbon5340-60Volatile matter2015-40Moisture

TypicalRangeProximate analysis

Value %Typical data of

proximate analysis




When MSW is heated at very high temperature the ash formed will convert into solid form as clinker by fusion and agglomeration.

This characteristic is important while designing incinerator and its by-products.

Normally, ash has fusing point at 1100~12000C

2. Fusing point of ash

Determination of heat of combustion when SW is burntThere are three methods of determining energy content:

Full scale boiler as calorimeterBomb calorimeterCalculations using standard table. Normally energy content is

determined in dry mass basis.

3. Energy content

105008000-12000Total in MSW kJ/kg1400012000-16000Organic fraction kJ/kgTypicalRangeHeating value kJ/kg

Value



ΣEC Municipal solid waste

70002300-11650Dirt, ashes, brickbats etc.700250-1200Tins/cans150100-250Glass

1860017450-19800Wood65002300-18600Garden trimmings1745015100-19800Leather2325020900-27900Rubber1745015100-18600Textiles3260027900-37200Plastics1675011600-18600Paper46503500-7000Food wastes

TypicalRangeEnergy kJ/kg

Components

Typical energy contents of various components of MSW




i) Unit energy content (as discarded) = ΣEC / ΣM

ii) Determining energy content at dry basisMoisture content of the MSW = MC

Energy content (as dry basis) ΣEC * 100 / (100 – MC) kJ/kg

iv) Determining the energy content on an ash-free dry basis= ΣEC * 100 / (100 – MC - % ash) kJ/kg

Modified Dulongs FormulakJ/kg = 337 C + 1428 (H – O/8) + 95S

WhereC = carbon %H = Hydrogen %O = Oxygen %S = Sulphur %




What is the heat value of PVC?

PVC = C2 H Cl%C = (2*12)

{(2*12)+(1*1)+(1*35.45)}

%H = (1*1){(2*12)+(1*1)+(1*35.45)}

Applying Modified Dulong’s Equation

kJ/kg = 337 * 39.7 + 1428 * 1.65 = 15735.1 kJ/kg

What is the heat value of Ethanol ?

Ethanol = CH3 CH2 OH

= 39.70%

= 1.65%




To determine basic elements that compose the solid wasteHelps to determine harmful affects to atmosphere when released as fumes –chlorinated and sulphur compounds, etc.Determines C, H, O, N, S and ash Helps to characterize the chemical composition of the organic matter in MSWHelps to determine C/N ratio for biological activities

4. Ultimate analysis (elemental analysis)




Biological properties:1. Most of the organic fraction of MSW lies within following seven

groups (excluding plastics, rubber and leather)

Water soluble constituents- sugar, starch, amino acids, and various organic acids

Hemi-cellulose – a condensation product of 5-carbon sugar and 6- carbon sugars

Cellulose - a condensation product of the 6-carbon sugar glucose,

Fats, oils, and waxes- are esters of alcohols and long-chain fatty acids.

Protein- chain of amino acids

Lignin- a complex polymer occurring in certain plant cell walls making it rigid, wood

Ligno-cellulose- combination of lignin and cellulose




2. Biodegradability of organic waste componentsFood waste

Paper

Cardboard

Yard waste

Wood, leather, rubber (?)

Conceptual Waste Composition for Biodegradability Characterization

Biological Volatile Solids

(BVS)

Residual Volatile Solids

(RVS)

Inorganics

Water

Biological Volatile Solids (BVS) is the fraction of degradable components “destroyed” during treatment Residual Volatile Solids (RVS) is the organic fraction of Biodegradable components that remains after treatment + plastic

Inorganic: glass, metal, dirt + inorganic part of biodegradable materials




.

How to determine BVS? Run a test in the lab and measure: normally ignition at 5500C is often used. This is misleading as some organic constituents (like news paper and some plant cells) are highly volatile but low in biodegradability.Analyze surrogate parameters and estimate: Lignin content of the waste can be used to estimate biodegradable fraction

Biodegradable Fraction BF = (BVS/VS) = 0.83 – 0.028 (LC)Where BVS = Biological Volatile Solids;

VS = Volatile Solids 0.83 and 0.028 are empirical constantsLC = Lignin content of the VS in % of dry weight

Biodegradability varies with the components, for simplicity MSW are classified as rapidly decomposable and slowly decomposable 0.724.150~90Yard wastes

0.4712.994Cardboard

0.820.496.4Office paper

0.2221.994Newspaper

Paper

0.820.47~15Food wastes

Biodegradable Fraction BF

Lignin Content (LC) % of VS

Volatile solids (VS) % of total solids (TS)Component

BF of selected organic waste components based on lignin content LC




3. Production of odourOdour is developed in solid waste due to anaerobic decomposition of readily decomposable organic compounds

In the process of reducing the putrescible waste in anaerobic condition Sulphate is reduced to sulphide (S2-) which subsequently combining with hydrogen forms H2S giving rise to bad odor Food waste

2CH3CHOHCOOH + SO42- → 2CH3COOH + S2- + H2O + CO2

Lactate Sulphate Acetate Sulphide ion

4H2 + SO42- → S2- + 4H2O

S2- + 2H+ → H2S (hydrogen sulphide)




The sulphide ion can also combine with metal salts to form metal sulphides

S2- + Fe2+ → Fe S (Iron sulphide)The black color of leachate in the solid wastes is due to these metal sulphides.

The positive side of formation of metal sulphides in the landfills is otherwise formation of H2S giving odor problem.

Biochemical reduction of methionine to methyl mercaptane and amino-butyric acid and subsequent hydrolysis to methyle alcohol and hydrogen sulphide

+2H

CH3 SCH2CH2CH(NH2)COOH → CH3SH + CH3CH2CH2(NH2) COOHMethionine Methyl mercaptane Amino-butyric acid

CH3 SH + H2O → CH4OH + H2SMethyle alcohol





Waste Generation StudyEstimation of waste generation:

Planning waste generation study:

Few considerations need to be borne in mind while planning the study

What is the use of the study information?

Is that the right season, month, day for the survey?

What are the components of the waste we need to consider, density, volume, etc. ?How extensive are we making the study?Area coverage, sectoral coverage, representative data?



Total waste generated includes:At household level:

Waste collected from HH/source (Wh)+ salvage by house owner/servant

+ salvage by scavengers from house+ waste disposed on unauthorized places

At transfer station (Wt):Wh - salvage by collector (door to door collection)

- salvage at transfer stationAt disposal site (Wd):

Wt – salvage by scavengers at disposal site- salvage by disposal staff

Comprehensiveness in the sources of waste




Methods of estimation of waste quantities:

Load count analysisWeight –volume analysisMass balance analysis

Load count analysisNormally 8-day continuous survey neededOut of the eight days, first day collection is discardedAt least 100~200 kg samples are analyzed.For seasonal variations several studies are needed in different seasons



Steps:No. of individual loads and the type of waste noted over a specified period of timeQuarter the waste – select the quarter of quarter until sample size is reduced to 100~200 kgs.

Separate all individual components of the waste according to their typesPlace the separated components in containers of known volume andtare mass. Try to compact the waste as found in the collection container.Determine mass of each type of waste by weighingDetermine % distribution of each component by mass as discarded density



Weight - Volume Analysis:This is easier method where weighing bridge is available in the transfer station/disposal site.

The volume and density of each truck load is noted to collect data on waste generation each day.

The limitation may be of composition of the waste.

Therefore, this can be conducted along with Load Count Analysis.



Mass balance method:Suitable for determining industrial waste generation.

Accumulation = inflow –outflow + generationdM / dt = Σ Min + Σ Mout + rw

Where dM / dt = rate of change of the material in the system, kg/dΣ Min = sum of all materials flowing into the system, kg/dΣ Mout = sum of all materials flowing out of the system, kg/d

rw = rate of waste generation, kg/dt = time, d

Stored materials(raw materials, products,

solid wastes)

Inflow materials

Outflow(combustion gases) and

ashes

Outflow(solid waste,

solids in waste water)

Outflow(materials)

Outflow(products)

System boundary




Working with concentrations1. Conversion from chemical concentration based on dry weight and

wet (or total) weight.Example:

Sludge from a waste water treatment plant has arsenic concentration of 0.6 mg/kg based on total weight.

What is the dry weight concentration of As if moisture content of the sludge is 80%?

0.6 mg As 1 kg wet sludge

X 1 kg wet sludge 0.2 kg dry sludge = 3.0 mg As

kg dry sludge




2. Finding average concentration of mixed waste.Example:

Considering two waste components:Sludge has 100 mg/kg (wet) Pb; solid content = 10%Wood chips has 300 mg/kg (wet) Pb; moisture content = 20%

What is the Pb concentration in the dry sludge if you cix the components in 50/50 mix by total weight?

0.6 mg As 1 kg wet sludge

X

swm lnotes ii-061

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