unit 1

UNIT 1

INTRODUCTION

• Human activities generate waste materials that are often discarded because they are considered Useless and unwanted. These wastes are normally solid.

• The word waste suggests that the material

SOURCES

• Sources of solid wastes in a community are, in general, related to land use and zoning.

(1)residential, (2)commercial, (3)Institutional,

(4)construction and demolition, (5)municipal services,

(6)treatment plant sites, (7)industrial, and

Sources and types of Solid Wastes

S.No Sources Types of solid wastes

1. Residential Food wastes, paper, cardboard, plastics, glass, tin cans, aluminum, other metal, ashes, textiles, leather, yard wastes, wood, street leaves, special wastes

(including bulky items, consumer

electronics, white goods, yard wastes collected separately, batteries, oil, and tires), and household hazardous

wastes

2. Commercial Paper, cardboard, plastics, wood, food wastes, glass, metal wastes, ashes, special wastes, hazardous wastes, etc.

3. Institutional Same as for commercial 4. Industrial (nonprocess

S.No Sources Types of solid wastes

5. Municipal solid waste* All of the preceding

6. Construction and demolition Wood, steel, concrete, dirt, etc.

7. Municipal services Special wastes, rubbish, street sweepings, landscape and tree trimmings, catchbeaches, other recreational, basin debris; general wastes from parks, beaches, and recreational areas.

8. Treatment facilities Treatment plant wastes, principally composed of residual sludges and other residual materials

9. Industrial Industrial process wastes, scrap, materials, etc.; nonindustrial waste, including food wastes, rubbish, ashes, demolition and construction wastes, special wastes, and hazardous waste

10. Agricultural Spoiled food wastes, agricultural

Increasing Waste Quantities

• _{The amount of MSW generated each year has}

continued to increase on both as per capita basis and as total generation rate basis.

• _{Current global MSW generation levels are}

approximately 1.3 billion tonnes per year, and are expected to increase to approximately 2.2 billion tonnes per year by 2025. This represents a

MUNICIPAL SOLID WASTE DEFINED

This definition states that MSW includes wastes from residential, commercial, institutional, and some industrial sources.

Generation refers to the amount of materials and products in MSW as they enter the waste stream before any materials recovery, composting or combustion take place.

Recovery refers to removal of materials from the waste stream for recycling or composting.

Recovery does not automatically equal recycling.

Discards refers to the MSW remaining after recovery. The discards are generally combusted or landfilled, but they could be littered, stored, or disposed on-site, particularly in

Factors influencing generation rate of

municipal wastes

• _{Geographic location} • _{Season of the year} • _{Collection frequency} • _{Population diversity} • _Recycling

Geographic location

• _{The influence of geographic location is related}

primarily to different climates that can influence both the amount of certain types of solid wastes generated and the collection operation.

• _{For instance, substantial variations in the amount of}

yard and garden wastes generated in various parts of India are related to the climate.

• _{To illustrate, in the warmer southern areas, where}

Seasons

• _{Seasons of the year have implications for the}

quantities and composition of certain types of solid wastes.

• _{For example, the growing season of}

Collection frequency

• _{A general observation is that in localities, where there are}

ultimate collection services, more wastes are collected.

• _{Note that this does not mean that more wastes are}

generated. For example, if a home owner has access to only one or two containers per week, due to limited container capacity, he or she will store newspapers or other materials in some specified storage area.

• _{However, the same homeowner will tend to throw them}

away, if there is access to unlimited container services. In this latter situation, the quantity of waste generated may actually be the same but the quantity collected, as it

Population diversity

• _{The characteristics of the population influence the}

quantity and composition of waste generated.

• _{The amount of waste generated is more in}

low-income areas compared to that in high-low-income areas.

• _{Similarly, the composition differs in terms of paper}

Recycling

• _{Recycling operation within a community}

Public attitude

• _{Significant reduction in the quantity of solid}

Legislation

• _{This refers to the existence of local and state}

regulations concerning the use and disposal of specific materials and is an important factor

that influences the composition and

generation of certain types of wastes.

• _{The Indian legislation dealing with packing and}

Interrelationship of functional elements

Waste generation

Storage

Collection

Disposal Transfer

&

Transport

METHODS OF CHARACTERIZING MUNICIPAL

SOLID WASTE

• _{There are two basic methods for} characterizing MSW

1. Sampling and

Methods of characterizing municipal solid

waste

Material Flow Sampling Characterizes residential, commercial,

Institutional and some industrial wastes Characterizes wastes received at the sampling facility Characterizes MSW nationwide In site specific

Characterizes MSW generation as well as

discards Usually characterizes only discards as recieved Characterizes MSW on an as-generated

moisture basis

Usually characterizes wastes after they have been mixed and moisture

transferred

Provides data on long-term trends Provides only one point in time (unless multiple samples are taken over a long period of time)

Characterizes MSW on an annual basis Provides data on seasonal fluctuations (if enough samples are taken)

Sampling & materials flow

• _{on-site sampling can be very expensive,}

especially if done with large enough samples and with the frequency required for reasonable accuracy.

• _{To date, only the material flows method has}

been used to characterize the MSW stream

Materials Flow

• _{Data on domestic production of the materials and products in municipal}

solid waste provide the basis of the material flows methodology.

• _{Every effort is made to obtain data series that are consistent from year}

to year rather than a single point in time. This allows the methodology to provide meaningful historical data that can be used for establishing time trends.

• _{Data sources include publications of the U.S. Department of Commerce}

and statistical reports published by various trade associations. Numerous adjustments are made to the raw

data, as follows:

Adjustment of Raw data

2. Where imports and/or exports are a significant portion of the products being characterized, adjustments are made, usually using U.S. Department of Commerce data. For example, more than half of the newsprint consumed in the United States is imported.

3. Adjustments are made for various diversions of products from disposal as MSW. Examples include toilet tissue, which goes into sewer systems rather than solid waste, and paperboard used in automobiles, which are not classified as MSW when disposed.

Adjustment of Raw data

• _{While the basis of the material flows methodology is adjusted}

production data, it is necessary to use the results of sampling studies to determine the generation of food wastes, yard

trimmings, and some miscellaneous inorganic wastes.

• _{A wide variety of sampling studies from all regions of the}

country over a long time period have been scrutinized to determine the relative percentages of these latter wastes in MSW.

• _{Since production data are as-generated rather than as-disposed,}

data on food, yard, and miscellaneous inorganic wastes are

Plastics

Effects of improper disposal of solid wastes

1. Loss of beauty (Aesthetic Effect 2. Highly Odorous

3. Toxic Gases

4. Spread of diseases

Effects of improper disposal of solid wastes

1. Loss of beauty (Aesthetic Effect):

• _{Litter and discard solid waste spoils the beauty}

of the area.

• _{The scene looks dirty and most people tend to}

the already spread waste. 2. Highly Odorous

• _{Stored or collected solid waste produces on}

3. Toxic Gases

• _{Municipal solid waste disposal sites or land fill} sites produces toxic gases like Hydrogen

sulphide (H2S), Methane (CH4), Carbon dioxide (CO2).

4. Spread of diseases

• _{Bacillary dysentery} • _Amoebic,

• _Dysentery • _Diarrhoea • _Cholera

5. Environmental Pollution

• _{Burning of solid waste} - _{Toxic gases}

- _{Dust or}

- _{Supended particles}

• _{Water pollution – leachate/percolation of waster}

water, Toxic substances get mixed with ground water

• _{Soil – plastic wastes – kills the microorganisms –}

6. Effect of bird diversity

Physical Propeties of MSW

• _{Specific Weight (Density)}

• _{Moisture Content}

• _{Particle Size and Distribution}

• _{Field Capacity}

Specific Weight (Density)

• _{Specific weight is defined as the weight of a} material per unit volume (e.g. kg/m3 , lb/ft3)

• _{Usually it refers to uncompacted waste.}

Typical Specific Weight Values

Component Specific Weight (density), kg/m3

Range Typical Food wastes 130-480 290

Paper 40-130 89

Plastics 40-130 64 Yard waste 65-225 100

Glass 160-480 194

Typical Specific Weight Values

Condition Density (kg/m3 )

Loose MSW, no processing or compaction 90-150 In compaction truck 355-530 Baled MSW 710-825 MSW in a compacted landfill (without

cover)

Moisture Content

• _{We can calculate the moisture percentage, using the formula given}

below:

• _{Moisture content (%) = Wet weight - Dry weight}

Wet weight Analysis Procedure:

• _{Weigh the aluminum dish}

• _{Fill the dish with SW sample and re-weigh}

• _{Dry SW + dish in an oven for at least 24 hrs at 105°C.}

• Remove the dish from the oven, allow to cool in a desiccator, and weigh.

• _{Record the weight of the dry SW + dish.}

• _{Calculate the moisture content (M) of the SW sample using the}

Typical Moisture Contents of Wastes

Type of waste Moisture content, %

Food 50 - 80

Paper 4 - 10

Plastics and glass 1-4 Yard waste 30 - 80 Chemical sludge 75-99

Saw dust 10-40

wood 30 - 60

Particle Size and Distribution

• _{The size and distribution of the components of} wastes are important for the recovery of

materials, especially when mechanical means are used, such as trommel screens and

magnetic separators.

• _{For example, ferrous items which are of a}

Field Capacity

• _{The total amount of moisture that can be retained} in a waste sample subject to the downward pull of gravity

• _{Field capacity is critically important in determining} the formation of leachate in landfills

• _{It varies with the degree of applied pressure and} the state of decomposition of wastes, but typical values for uncompacted commingled wastes from residential and commercial sources are in the

Permeability of Compacted Waste

• _{The permeability (hydraulic conductivity) of} compacted solid waste is an important

physical property because it governs the movement of liquids & gases in a landfill. • _{Permeability depends on;}

- Pore size distribution - Surface area

Chemical Properties of MSW

• _{Chemical properties of MSW are very} important in evaluating the alternative processing and recovery options:

- Proximate analysis - Fusing point of ash

Proximate analysis

• _{Proximate analysis for the combustible}

components of MSW includes the following tests: - Moisture (drying at 105 oC for 1 h)

- Volatile combustible matter (ignition at 950 o_{C in the absence of oxygen)}

- Fixed carbon (combustible residue left after Step 2)

Typical Proximate Analysis Values (% by

weight)

Type of Waste Moisture Volatiles Carbon Ash

Mixed food 70.0 21.4 3.6 5.0 Mixed paper 10.2 75.9 8.4 5.4 Mixed plastics 0.2 95.8 2.0 2 Yard wastes 60.0 42.3 7.3 0.4

Glass 2 - - 96-99

Residential

Fusing Point of Ash

• _{Fusing point of ash is the temperature at}

which the ash resulting from the burning of waste will form a solid (clinker) by fusion and agglomeration.

Ultimate Analysis

• _{Involves the determination of the percent C (carbon),}

H (hydrogen), O (oxygen), N (nitrogen), S (sulfur) and ash.

• _{The determination of halogens are often included in}

an ultimate analysis.

• _{The results are used to characterize the chemical}

composition of the organic matter in MSW. They are also used to define the proper mix of waste materials to achieve suitable C/N ratios for biological

What is solid waste management

Solid waste management refers to the

What are the essential reasons for an analysis of the composition, characteristics and quantities of

Physical characteristics

• _{Density: Density of waste, i.e., its mass per unit}

volume (kg/m3 ), is a critical factor in the design of a SWM system, e.g., the design of sanitary landfills, storage, types of collection and transport vehicles, etc. To explain, an efficient operation of a landfill demands compaction of wastes to optimum

Density

• _{Significant changes in density occur}

spontaneously as the waste moves from source to disposal, due to scavenging,

handling, wetting and drying by the weather, vibration in the collection vehicle and

Notes…

• _{the effect of increasing the moisture content of} the waste is detrimental in the sense that dry density decreases at higher moisture levels;

• _{soil-cover plays an important role in containing} the waste;

Moisture content:

• _{Moisture content is defined as the ratio of the weight of}

water (wet weight - dry weight) to the total weight of the wet waste. Moisture increases the weight of solid

wastes, and thereby, the cost of collection and transport.

• _{In addition, moisture content is a critical determinant in}

the economic feasibility of waste treatment by