ce2039 municipal solid waste management lecture notes
TRANSCRIPT
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CE2039 MUNICIPAL SOLID WASTE MANAGEMENT
LECTURE NOTES
By
G.BASKAR SINGH M.E.
Assistant Professor/Civil Engineering Department
S.VEERASAMY CHETTIAR COLLEGE OF ENGINEERING AND TECHNOLOGY
(NBA* NAAC* Accredited)
PULIYANGUDI,TIRUNELVELI(DIST)-627 855
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MUNICIPAL SOLID WASTE MANAGEMENT
CE 2039
LECTURE NOTES
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TABLE OF CONTENTS
UNIT TITLE PAGE
1 Sources and Types of Municipal Solid Wastes 120
2 On-Site Storage & Processing 2130
3 Collection and Transfer 3161
4 Off-Site Processing 62 - 101
5 Disposal 102 - 122
References
Glossary
Anna University Question Paper Nov-Dec 2012
Informations to knowMunicipal Solid Waste
Management
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Municipal Solid Waste Management
UnitI
Sources & Types of Municipal Solid Waste
Syllabus:
Sources and type of solid wastes Quantity Factors affecting generation of
solid wastes Characteristics Methods of sampling & characterization Effects of
improper disposal of solid wastes Public health effects Principle of solid waste
management
Social & economic aspects
Public awareness
Role of NGO &
Legislation
1.Principles of Municipal Solid waste Management
- Municipal Solid waste Management involves the application of Principle
of Integrated Solid waste Management (ISWM)
-
ISWM is the application of suitable techniques, technologies and
management programmes covering all types of solid wastes from all
sources.
-
ISWM has two objectives:
o Waste Reduction
o Effective management of waste still produced after waste reduction
- Waste Reduction: Itcan be done by following the policy, More with less
(i.e.) more goods / services with less use of Worlds resources (raw
materials & energy) and less pollution & waste. Waste reduction can also be
achieved by using internal recycling of materials (or) On-site energy
recovery.
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Ef fective Management of Soli d wastes:Effective solid waste management
systems are needed to ensure better human health and safety. They must be
safe for workers and safeguard public health by preventing the spread of
disease.
-
An effective management system must be both environmentally and
economically sustainable.
(a)Environmentally Sustainable: It must reduce as much as possible, the
environmental impacts of waste management.
(b)
Economically Sustainable: It must operate at a cost acceptable to the
community
- An effective waste management system includes one (or) more of the
following options
(a)Waste collection & Transportation
(b)Resource recovery through sorting & recycling (through separation)
(c)Resource recovery through waste processing (through bio / thermal process)
(d)
Waste transformation (without recovery of resources)
(e)Disposal on land (i.e.) environmentally safe and sustainable disposal in
landfill
2. Functional Elements of MSWM
The activities associated with the management of municipal solid wastes
from the point of generation to final disposal can be grouped into 6 elements as
follows:
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Waste Generation:
-
Waste generation contains activities in which materials are identified as
no longer being of value (no usefulness) and are either thrown away (or)
gathered together for disposal.
- Waste generation is at present, an activity that is not very controllable. In
the future, more control is likely to be exercised over the generation ofwastes.
Waste Handl ing, Sorting, Storage & Processing @ sour ce:
- The 2nd
of 6 functional elements in the solid waste management.
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Waste handling and sorting involves the activities associated with
management of wastes until they are placed in storage containers for
collection.
-
Sorting of waste components is an important step in the handling and
storage of solid wastes at source.
- On site storage is of primary importance because of public health
concerns and aesthetics consideration.
-
Processing at the source involves activities such as backyard waste
composting.
Collection:
- The functional element of collection, includes not only the gathering of
solid wastes and recyclable materials, but also the transport of these
materials after collection to the location where collection vehicle is emptied.
Sorting, Processing & Transformation of soli d wastes:
-
Its the 4th
of MSWMs functional elements.
- Sorting of mixed materials recovery facility (MRF), transfer stations,
combustion facilities and disposal sites. It includes the separation of waste
components (by size), separation of ferrous & non-ferrous materials.
- Waste processing is undertaken to recover, conversion products &
energy. The commonly used thermal processing is incineration.
- Waste transformation is undertaken to reduce volume, weight (or) size
(or) toxicity of waste without recovery. It can be done by mechanical,
thermal, chemical techniques.
Transfer & Transport: This involves two steps.
- The transfer of wastes from the smaller collection vehicle to the larger
transport equipment.
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- The subsequent transport of wastes, over a longer distances to processing
disposal site.
Disposal:
-
The final functional element in the solid waste management system is
disposal.
- A municipal solid waste landfill plant is an engineered facility used for
disposing of solid wastes on land without creating nuisance (or) hazard to
public health (or) safety.
3.
Sources of solid wastes
Sl. Wastes Sources Examples
No
1 Residential Single & multifamily Food wastes, paper,
dwellings card board, plastics,
textiles, leather, yard
wastes, metals, ashes,
etc.,
2 Industrial Light & heavy House keeping wastes,
manufacturing, packaging, food
fabrication, wastes, hazardous
construction sites, wastes, etc.,
power & chemical
plants
3 Commercial Stores, hotels, Paper, cardboard,
restaurants, markets, plastics, wood, glass,
office buildings. metals, etc.,
4 Institutional Schools, hospitals, Same as commercial
prisons, govt. centres
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5 Construction & New construction Wood, steel, concrete
Demolition sites, road repair,
renovation sites,
demolition o
buildings
6 Municipal Street cleaning, Industrial process
Services landscaping, parks, wastes, scrap
beaches, etc., materials, off-
specification products,
slag tailings
4. Types of Solid wastes
In order to plan, design and operate a solid waste management system, a
thorough knowledge of the quantities generated, the composition of wastes and
its characteristics are essential. Based on the source, origin and type of waste,
types of solid wastes is given below:
Domestic and Residential Wastes
- These are originated from single & multi-family household units.
- These are generated as a consequence of household activities such as
cooking, cleaning, repairs, hobbies, redecoration, empty containers,
packaging, clothing.
Municipal Wastes
-
It includes wastes resulting from municipal activities and services such
as street waste, dead animals, market waste & abandoned vehicles.
- This term is commonly applied in a wider sense to incorporate domestic
wastes, institutional wastes & commercial wastes.
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Commercial Wastes
- It includes wastes produced from offices, wholesale and retail stores,
restaurants, hotels, markets, warehouses.
I nstitutional Wastes
-
These are arising from institutions such as schools, universities, hospitals
& research institutes.
- It includes wastes which are classified as garbage & rubbish.
Garbage
-
Its the term applied to animal & vegetable wastes resulting from the
handling, storage, sale, preparation, cooking & serving of food
- These wastes contains putrescible organic matter, which produces strong
odor, so requires quick attention in its storage
Rubbish
- Its a general term applied to solid wastes generating in house holds,
commercial establishments & institutions, excluding garbage & ashes.
Ashes
- Ashes contains of a fine powdery residue, cinders & clinker often mixed
with small pieces of metal & glass.
-
Ashes are the residues from the burning of wood, coal, charcoal, coke &
other combustible materials
Bulky Wastes
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These are house hold wastes which cannot be accommodated in the
normal storage containers of house holds. So, they require special
collection.
-
This includes large household appliances such as cookers, refrigerators,
washing machines, furniture, crates, vehicle parts, tyres, wood.
Street Sweeping
-
This term indicates that are collected from streets, walkways, alleys,
parks & vacant lots.
- Street wastes includes paper, cardboard, plastic, dirt, dust, leaves & other
vegetable matters.
Dead animals
- This term applied to dead animals that die naturally (or) accidentally
killed. These are divided into 2 groups; large & small.
-
Large animals are horses, cows, goats, sheep. Small animals are dogs,
cats, rabbits & rats.
Construction & demoli tion Wastes
I ndustrial Wastes
Hazardous Wastes
Sewage Wastes
5.Quantity of Solid Wastes
-
The measurement of quality of solid wastes generated is becoming
significant in accessing thepayload capacityof the collection equipment.
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- Also important in designing and planning a solid waste management
system.
6. Factors affecting Generation of Solid wastes
Ef fect of source reduction
- Waste reduction may occur through the design, manufacture and
packaging of products with minimum toxic content, minimum volume of
material, source reduction can also be achieved by:
-
Decrease unnecessary (or) excessive packaging- Develop & use products with greater durability
-
Use fewer resources ( e.g: 2 sided copying)
- Increase the recycled materials content of products.
Extent of Recycling
- The existence of recycling programmes within a community definitely
affects the quantities of wastes collected for further processing (or) disposal.
Ef fect of Publ ic attitudes & Legislation
- Public attitudes ultimately, does significant reduction in the quantities of
solid wastes generated.
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A programme of continuing education is essential in bringing about a
change in public attitudes.
- It depends upon the willingness of people to change their own volition,
habits & lifestyles.
-
Legislation perhaps the most important factor affecting the generation of
certain types of wastes such as package & beverage container materials.
Geographic Location
-
Physical factor that affects the quantity of waste generated including
location, season of the year, the use of kitchen waste food grinders, waste
collection frequency.
-
Different climate influences both the amount of certain types of solid
wastes generated & the time period over which the wastes are generated.
- (e.g.) substantial variations in the amount of yard & garden wastes
generated in various parts of the country are related to climates.
Season of the year
- The quantities of certain types of solid wastes are also affected by the
season of the year. (e.g.) Festivals of India is totally a various thing overall.
Depending upon the type & change of festivals, waste generation is
different.
Frequency of Coll ection
- In general, where unlimited collection service is provided, more wastes
are collected. It does not mean that wastes are generated in more quantity.
But, it means the tendency of throwing away the wastes respective of
frequency of collection.
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Character istics of Service Area
- Peculiarities of the service area can influence the quantity of solid wastes
generated. (e.g.) Quantities of yard wastes generated on a per capita basis
are considerably greater in many of the wealthier neighborhood than in
other parts of town.
7. Characteristics of Solid Wastes
7.1 Physical Characteristics
Density (Mass per unit volume)
-
Knowledge of the density of a waste is essential for the design of all
elements of SWM, such as community storage, transportation and disposal.
- A reduction of volume of 75% is frequently achieved with normal
compaction equipment, so that an initial density of 100 kg / m3will readily
be increased to 400 kg /m3.
-
Density is an critical in the design of a sanitary landfill as it is for thestorage, collection & transportation of waste.
- Measurement of Density: The solid wastes should be taken in thesmaller
0.028 m3box to give a composite sample, from different parts of heap of
wastes.
-
After weighing, this smaller box (0.028 m3) is emptied in bigger 1m
3
box.
- Continue the process until bigger box is filled to the top. The waste
should not be compacted by pressure.
-
Fill 1m3box three times, and take the average. Thus weight per m
3 is
obtained.
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Moisture Content
- Moisture content of solid wastes is usually expressed as the weight of
moisture per unit weight of the wet material.
- A typical range of moisture contents is 20 - 45 %, representing the
extremes of wastes in an arid climate.
-
Moisture content is a critical determinant in the economic feasibility of
waste treatment plants.
- Apart climatic conditions, moisture content is generally higher in lower
income countries because of the higher proportion of food & yard wastes.
Size of waste consti tuents
- The size distribution of waste constituents in the waste stream is important
because of its significance in the design of mechanical separators and
shredder & waste treatment process.
Calorif ic Value
- Its the amount of heat generated from combustion of a unit weight of a
substance, expressed as Kcal / kg.
-
This value is measured experimentally using Bomb Calorimeter in
which the heat generated at a constant temperature of 25 C from the
combustion of a dry sample is measured.
7.2
Chemical Characteristics
Knowledge of chemical characteristics of waste is essential in
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determining the efficacy of any treatment process. Chemical characteristics
includes (i) Chemical (ii) Bio-chemical (iii) Toxic
Chemical
- It includes pH, Nitrogen, Phosphorous & Potassium (N-P-K), Totalcarbon, C/N Ratio, Calorific value.
Bio-Chemical
- It includes carbohydrates, proteins, natural fibers & biodegradable factors.
Toxic
- It includes heavy metals, pesticides, insecticides, toxicity test for leachates(TCLP)
8. Methods of Sampling
8.1
Collection of Samples of solid wastes
- When collecting samples of municipal solid waste, major collection sites
are identified which are covering a large size of population?
- Based on the type of area such as residential, commercial, and industrial,
market, slum etc., sampling points are distributed uniformly over the study
area.
-
About 10 kg of Municipal Solid waste (MSW) is collected from ten
points from outside & inside of the solid waste heap.
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Ground water contamination by the leach generated by the waste dumb.
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Surface water contamination by the run-off from the waste dumb.
- Bad odor, pests, rodents and wind-blown litter in and around the waste
dumb.
-
Generation of inflammable gas (methane) within the waste dumb.
-
Bird menace above the waste dumb which affects flight of aircraft.
- Fires within the waste dumb.
- Erosion & stability problems relating to slopes of the waste dumb.
- Epidemics through stray animals.
-
Acidity to surrounding soil & release of greenhouse gas.
9.2 Impact on Public Health
-
Exposure to hazardous waste can affect human health, children
being more vulnerable to these pollutants. Also, it leads to chemical
poisoning due to chemical mix in the wastes.
-
Direct handling of solid wastes contains Organic domestic wastes in
various types of infectious and chronic diseases with the waste workers &
the rag pickers.
- Waste from agr iculture and industr ies can also cause serious
health risks such as chemical & radioactive hazards.
- Waste treatment & disposal sites can also create health hazards for
the neighborhood. Improperly operated incineration plants cause air
pollution & improperly managed & designed landfills attracts all types of
insects and rodents that spread diseases.
- Recycling too carries health risks if proper precautions are not taken.
Workers working with waste containing chemical & metals may experience
toxic exposure.
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11. Role of Legislation and NGO on MSWM
11.1 Role of Legislation
- River & Harbours Act, 1899 regulated the dumping of debris in
navigable waters and adjacent land. The idea was to protect the navigation.
- Solid Waste Disposal Act, 1965. The intention was:
o To promote solid waste management & resource
recoveryo To promote technical & financial aid
o To promote national research
- Public Util ity Regulation & Poli cy Act ( PURPA) 1981, it directs public
& private utilities to purchase power from waste to energy facilities.
- Comprehensive Environmental Response, Compensation & Liabil i ty
Act, (CERCLA), 1980, it gives response to uncontrolled hazardous waste
disposal sites.
- Resource Conservation & Recovery Act (RCRA), 1976
o Its theLegal basis for implementation of guidelines and standards
for solid waste storage, treatment & disposal.
o RCRA was amended in 1978, 1980, 1982, 1983, 1984, 1986 & 1988.
The 1980 and 1984 versions emphesized with hazardous waste.
-
National Environmental Policy Act (NEPA), 1969
- Resource Recovery Act, 1970.
-
MSW Rules 2000 (India), these rules lay down the steps to be taken by
all municipal authorities to ensure management of solid waste according to
best practice.
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11.2 Role of Non-Governmental Organizations (NGO)
- Non-Governmental organizations (NGOs) are yet another set of
participants in waste management operations.
-
NGOs are often commissioned to improve the environment of the quality
of life of poor marginalized populations, and may stimulate small-scale
enterprises and other projects.
-
Since waste materials often represent the only growing resource stream,
these organizations frequently base their efforts in extracting certain
materials.
-
The some locations with insufficient collection (or) whereneighborhoods are underserved, community based organizations play an
active role in waste management operations.
- These small-scale organizations (or) local NGOs are formed primarily as
self-help (or) self-reliance units, which may evolve into service
organizations that collect fees from their collection clients and from the sale
of recovered materials.
-
NGOs working with informal workers and community based
entrepreneurs often seek recognition for these organizations as part of the
waste management systems.
-
12. Public Awareness and Training
-
Public Awareness is an important activity in solid wastemanagement to keep the system sustainable. The information related to
public awareness is necessary for creating a sustainable system.
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12.1Partnership Role for Public Awareness
-NGO
-
CBO
12.2Mode of Implementing Public Awareness Programmes
1.
Audio & Video program
2.
IEC program
3.Child to child education
4.School education
12.3Public Participation
- Total number of sweepers allotted for door to door waste collection
work in each ward.
-
Number of sweepers getting good response from citizens in the matter of
doorstep collection.
- Number of sweepers not getting response from the public.
- Percentage of public participation.
-
Improvement of the area than the previous month.
13.
Economic Aspects of MSWM
-
Presently a large proportion of the total expenditure is incurred oncollection, a bit lesser on transportation & ameagre amount on disposal.
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Municipal Solid Waste Management
Unit II
On-Site Storage & Processing
Syllabus:-
On-Site storage methods Materials used for containers On-Site
segregation of solid wastes Public health & economic aspects of storage
Options under Indian conditionsCritical evaluation of options.
1. Introduction
-The handling, storage and processing of solid wastes at the source
before they are collected is the 2nd
of 6 functional elements of MSWM.
-
It is important to understand, what this element involves? This unit
includes a description and discussion of the Handling, Storage and
Processing of waste materialsat the sour ce.
2. On-Site Handling
-On-Site handling methods and principles involves public attitude,
individual belief and ultimately affects the public health.
-Its an activity associated with the handling of solid waste until they
are placed in containers.
2.1 Importance of On-Site Handling
(a) Reduce volume of waste generated
(b) Alter physical form (c) Recover usable material
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2.2 On-Site Handling Methods
(a) Sorting
(b) Shredding
(c)
Grinding
(d) Composting
3. On-Site Storage
- The first phase to manage solid waste is at home level. It requires
facilities for temporarily storing of refuse on the premises.
-
Individual house holders (or) businessman have responsibility for on-
site storage of solid waste.
-Four factors that should be considered in the on-site storage of solid
waste are: type of containerto be used, the location of containers, publi c
health, coll ection method / time.
3.1
Storage Container
-Garbage and refuse generated in kitchens and other work areas should
be collected and stored in properly designed and constructed water-proof
garbage cans ( waste bins ).
-The cans can be constructed from galvani zed i ron sheets(or) plastic
materials.
-
They should have tightly fitting covers. They must be of such size
that, when full, can be lifted easily by one man.
-They should be located in a cool place over platforms, at least 30 cm
above ground level.
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-The bins must be emptied at least daily and maintained in clean
conditions.
-A typical example of garbage can, constructed from galvanized iron
sheet, dimensions: 45 cm diameter, height 75 cm.
-
An adequate number of suitable containers should be provided with
proper platforms with stand.
-Suitable containers shall be water tight, rust resistant, tight f itt ing covers,
fi re resistant, enough size, li ght in weight, side handle & washable.
3.2 Storage containers as per Indian Conditions
- The segregation of garbage at source isPrimarily meant to keep the
two broad categories of solid waste generated separately in different
containers (i.e.) bio degradable waste in one container (GREEN)and non-
bio degradable waste in another container (RED).
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- The storage of garbage used by pedestrians (or) the floating
populations, bins should be located at regular intervals. The bins should be
placed on TWO BINS BASIS
-
Some types of receptacles presently used for storage are:
(a) Buckets
(b) Plastics / HDPE / MDPE bins
(c)
Plastic bags
(d)
Metal bins with (or) without lids.
-The MSW Rules, 2000 describes, The litter ing of municipal soli d
waste shal l be prohibited in citi es, towns and in urban areas noti fi ed bythe State Government
3.3 Container Size ( Capacity )
Considerations should be given for the size of the loaded container
that must be hauled to the collection vehicle (or) to the disposal site.
Therefore, container size for:
-
Ash up to 80 to 128 lit
-
Mixed refuse up to 120 to 128 lit
- Rubbish up to 200 lit
- Office waste is 10 to 20 lit
- Kitchen waste is 40 lit
-
Garbage is 48 to 80 lit
-Plastic liners for cans and wrapping for garbage reduce the need for
cleaning of cans and bulk containers. It avoids bad odors, rat and fly
breeding.
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Galvanized metal is preferable for garbage storage because it is
resistant to corrosion.
- Bulk containers are recommended where large volumes of refuse are
generated such as hotels, restaurants, apartment houses, shopping centres.
4. On-Site Processing / Segregation
On site segregation is intended:
(a) To improve disposal options
(b)
To recover valuable resources(c) To prepare materials for recovery as new products (or) energy
4.1 Objectives of On-Site waste Processing / Segregation
- Compound Separation ( Hand sorting, screening )
- Volume reduction ( baling, shredding )
-
Size reduction ( shredding, grinding )- Resource recovery ( composting )
4.2 Critical Evaluation of Options
- In case of On-Site processing of solid wastes, there are more number
of methods may be available.
-
But, one engineer should know to evaluate the various methods and
should be able to pick up a better and better solution suitable to the local
conditions.
-
The various factors that enters in, when deciding the best suitable
method are:
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(a)
Systems impact on local & global environment
(b)
Reliability
(c) Safety to workers and to local community
(d)
Ease of operations
(e)
Efficiency
(f)
Economics & aesthetics (noise, odors. Litter, increased traffic)
- A number of processing technologies have been developed for solid
waste management and one of the jobs of an engineer is to select and
design the most sustainable and cost effective methods for a given
community.
5.
On-Site Segregation, Storage & Processing Options under
Indian Conditions
Over all process of MSWM is shown here:
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5.1 Definition of Segregation
- Segregation indicates separation and storage of individual constituents
of waste materials on site.
Fig: On-Site Storage containers located in Tindivanam (2011)
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5.2 Segregation at Dwellings
There are three classifications most often used,
(a)Low rise buildings ( < 4 stories )
a.
Single family detached
b. Single family attached
(b)Medium rise buildings ( 4-7 stories )
(c)High rise buildings ( > 7 stories )
5.2.1 Low rise detached dwelling
-
Here, the residents are responsible for placing the solid waste and
sorting out recyclables.
- In many communities, the decisions have been made, not to require
the residents to separate the waste.
- But, it should be mandated.
- The equipments & facilities required are, household compactors, large
wheeled containers, small wheeled hand carts.
5.2.2 Medium size apartments
-
The collection and sorting process differs according to location and
type of waste generated.
-
Some of the solid waste storage locations are:
Basement Storage / Curb Storage
Outdoor / Mechanized Storage
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5.2.2.1 Basement Storage
- Usually owner provides basement storage rooms and the
recycling containers located near (or) next to solid waste storage.
-
The residents are responsible for storing waste in the curb side.
- The maintenance staff is responsible for curb side collection to
the street collection.
5.2.2.2 Outdoor Storage
-
Here, the large containers are located at the outdoor (or) near
the apartments.
- The residents are responsible for disposing their waste in the
containers.
- The collection vehicles with unloading mechanism are always
preferred here
.
5.2.3
High rise Apartments
- Wastes are picked up by building maintenance personnel (or)
porters from the various floors and taken to the basement (or) service
area.
- Wastes are taken to the basements by tenants.
- Wastes discharged in chutes (or) collected in large containers,
compacted in to large containers.
- In many high rise apartments, solid waste chutes are used with
large compactors.
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6. Public health & Economic Aspects of On-Site Storage
6.1 Problems related to On-Site Sorting, Storage
The main problems of sorting of waste as it is carried out manually at
various stages are listed below:
(a) Waste gets scattered at the bins.
(b)
Some types of waste does not get recycled, since it is not
currently recyclables.
(c) Toxic (or) hazardous waste does not get collected and ends up
either in landfills (or) in composting operation. Both cause other
contamination such as of groundwater.
(d)
Recycling takes place in very poor health and environmentally
unsafe conditions
.
6.2 Desirable Changes to be happened
The following long-term changes are desirable:
(a)
Organized colony-wise collection systems involving rag pickers,with proper gear and protection.
(b) Investments in the recycling sector to ensure that the units are
safe and operate at economic scales.
(c) Development of recycling laws for specific types of wastes.
(d)
Promotion of simple disinfection techniques and devices such as
needle cutter for infectious waste to be pre-treated before disposal.
(e) Pre-sorting of waste for composting operations, through
mechanical means.
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Municipal Solid Waste Management
Unit III
Collection & Transfer
Syllabus:-
Methods of collection Types of vehicles Manpower requirement
Collection routesTransfer StationsSelection of locations, operations &
maintenanceOptions under Indian conditions
1.Introduction:
-
In the Municipal Solid waste Management system, Collection is an
important aspect.
- It is carried out in 5 different phases as discussed below:
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Phase 1: The individual house owner must transfer whatever is
considered as waste to the refuse can, which may be inside (or) outside the
home.
Phase 2: The movement of the refuse can to the truck, which is usually
done by the collection crew, called backyard collection.It the can is moved
to the street by the home occupant, the system is called, curbside collection
Phase 3: More & more separated materials and yard wastes are collected
separately either in same truck (or) in separate vehicles from house to
house.
Phase 4: This phase is known as truck routing. The trucks must collectthe refuse from many homes in the most efficient way possible.
Phase 5: The fifth phase of the collection system involves the location of
the final destination (e.g: MRF, disposal site, transfer station)
2. Collection Components:
Components of a solid waste collection system can be listed as below:-
Collection Points
-
Collection Frequency
- Storage Containers
- Collection Crew
-
Collection Route
-
Transfer Station
Collection Poin ts :It depends on the locality that may be residential, commercial
(or) industrial. It has the deciding factors such as size & storage which ultimately
affect the cost of collection.
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Collection Frequency:
-
Climatic conditions and requirements of a locality as well as
containers and costs determine the collection frequency.
- In hot and humid climates, solid wastes must be collected atleast
twice a week because the decomposing solid wastes produce bad
odour & leachate.
- In residential areas (food & other putrescible wastes), frequent
collection is desirable for health & aesthetic reasons.
- While deciding the collection frequency, following factors must be
kept in mind; cost, storage space, sanitation.
Storage Containers:
- Proper container selection can save the collection energy, increase
the speed of collection and reduce crow size, while evaluating
residential waste containers, the following factors must be kept in
mind.
- Efficiency: The containers should help to maximize the over all
collection efficiency.
- Convenience: The containers must be easily manageable both for
residents and collection crew.
- Compatibility The containers must be compatible with collection
equipment.
-
Public Health & Safety: The containers should be securely covered
and stored.
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Transfer Station:
-
A transfer station is an intermediate station between final disposal
option and collection points in order to increase the efficiency of
the system, as collection vehicles and crew remain closer to routes.
- A centralized sorting and recovery of recyclable materials are also
carried out at transfer station.
- The unit cost of hauling solid wastes from a collection area to a
transfer station and then to a disposal site decreases when the size
of the collection vehicles increases.
3. Methods of Primary Collection of wastes
3.1 Door step Collection through Containerized Hand carts:
- A bellmay be affixed to the handcart given to the sweeper
(or) a whistle may be provided.
- Each sweeper maybe given a fixed area (or) stretch of
houses for the collection of wastes.
Area Allotment / Sweeper
(i) Thickly Populated - 250 to 350 RMT
(ii) Less Populated - 400 to 600 RMT
(iii) Low density - 650 to 750 RMT
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3.2 Role of Sweeper:
- The sweeper should ring the bell (or) blow the whistle indicating his
arrival at the place of his work and start sweeping the street.
- On hearing the bell (or) whistle, people should deposit their
domestic biodegradable waste into the handcart of sweeper.
- No sweeper may be expected (or) directed to do house-to-house
collection by asking for waste at the door steps, as this will affect his energy &
productivity.
3.3 Collection through Motorized Vehicles:
- Local bodies, as an alternative to door step collection through
containerized handcarts may deploy motorized vehicles having unconventional
horn for doorstep collection of waste.
- Driver of vehicle should blow the horn to indicate his arrival, and
householders should deposit their domestic wastes directly into the vehicle without
loss of time.
3.4 Primary Collection of waste from Societies / Complexes:
- It is made compulsory for the management of the societies,
complexes and multi-storied builders to keep community bins (or) containers in
which dry & wet wastes may be stored separately by their residents.
- To facilitate collection of waste from societies (or) complexes, the
local bodies should act by a rule, make it obligatory for them to identify an
appropriate site within their premises for keeping such bins for waste storage.
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3.5 Collection of waste from slums:
- Local bodies should collect waste from slum by bell ringing /
whistle system along their main access-lanes.
-
Residents should bring their wastes from their houses to handcarts.
-
Performance certification by a Mohalla (Local level) Committee
may be insisted upon in such cases.
3.6 Collection-at-the doorstep in Posh Areas:
- In posh residential areas where the residents as a whole might not be
willing to bring their wastes to the municipal handcart, system of collection from
the doorstep on full cost recovery basis may be introduced.
4.Types of Collection Vehicles
- Almost all collections are based on collector and collection crews,
which move through the collection service area with a vehicle for collecting the
waste material.
-
The collection vehicle selected must be appropriate to the terrain, type
and density of waste generation.
-
The most commonly used collection vehicle is the dump truck fittedwith a hydraulic lifting mechanism. A description of some vehicles types
follows:
(i) Small-Scale Collection & Muscle-powered Vehicles
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(ii) Non-Compactor Trucks &
Compactor Trucks
4.1
Small-scale Collection & Muscle Powered Vehicles:
- These are common vehicles used for waste collection in many countries
and are generally used in rural hilly areas.
- These can be small rickshaws, carts, (or) wagons pulled by people (or)
animals, and are less expensive, easier to build and maintain compared to
other vehicles.
-
They are suitable for densely populated areas with narrow lanes, andsquatter settlements, where there is relatively low volume of waste
generated.
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4.2 Non-Compactor Trucks:
- Non-Compactor trucks are efficient and cost effective in small cities
and in areas where wastes tend to be very dense and have only little potential
for compaction.
- When these trucks are used for waste collection, they need a dumping
system to easily discharge the waste.
-
It is generally required to cover the trucks in order to prevent residue
flying off (or) rain soaking the wastes.
-
Trucks with capacities of 10-12 m3 are effective, if the distance
between the disposal site and the collection area is less than 15Km.
-
Non-compactor are generally used when labour cost is high.
4.3 Compactor Trucks:
- Compactor vehicles are more common these days, generally having
capacities of 12-15 m3due to limitations imposed by narrow roads.
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The advantages of the compactor collection vehicles include the following:
(a)
Container are uniform, large, covered and relatively visually inoffensive.
(b)
Waste is set out in containers so that the crew can pick them up quickly.
( c ) Health risks to the collectors and odor on the streets are minimized.
(d) Waste is relatively inaccessible to the waste pickers.
5. Collection Vehicle Routing
- Efficient routing and re-routing of solid waste collection vehicles
can help to decrease the cost by reducing the labour expended for collection.
- Routing procedures usually consists of the following two separate
components:
(a)Macro RoutingDefining size of routes
(b)Micro RoutingDefining exact path of each route
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- Results of micro-routing analysis should also be done by the
review of experienced collection drivers.
5.3 Deciding Factors for Collection Vehicle Routing:
- The heuristic (trial & error) route development process is a
relatively simple manual approach that applies specific routing patterns to blockconfigurations.
- The map should show collection, service locations, disposal (or)
transfer sites, one-way streets, natural barriers and the area of heavy traffic flows.
- Then, routes should be traced out onto the tracing paper using
the following factors:
(a)
Routes should not be fragmented (or) overlapping.
(b)Total collection (+) Hauling time reasonably constant for each route in
the community.
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( c ) The collection route should be started as close to the garage (or) motor pool as
possible.
(d)
Heavily travelled streets should not be visited during rush hours.
(e)
In case of one-way streets, it is best to start the route near the upper end of
the street.
(f)
In case of dead-end streets, wastes must be collected by walking down,
reversing the vehicle (or) taking a U-turn.
(g)
Higher elevations should be at the start of the route.
(h)For collection from one side of the street at a time, it is generally best to route
with many anti-clockwise turns around the blocks.
Based on the above rules, a typical vehicle routing is illustrated below:
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6.Transfer Stations
-When the waste disposal unit is remote to the collection area, a transfer
station is employed.
-
A transfer station is an intermediate station between final disposal option
and collection point in order to increase the efficiency of the system, as collection
vehicles & crew remain closer to routes.
-
In some situations, the transfer stations serves as a pre-processing plant,
where wastes are dewatered & compressed.
-A centralized sorting and recovery of recyclable materials are also
carried out at the transfer station.
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6.1 Basic Transfer Technologies:
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Selecting sites that have direct access to truck routes, highways and
rail terminals.
-
Providing adequate space within the facility site so that customers
waiting to use the transfer station do not interrupt traffic on public roads.
-Arranging the site so that traffic flows are not adjacent to properties
that are sensitive to noise.
-The site should large enough to accommodate all required functions and
possibly future expansion should be centrally located in the area where waste is
generated.
6.5Operation & Maintenance of a Transfer Station
-Six categories can be finalized and can be explained under Operation &
Maintenance of a Transfer Station. They are:
(i)Operation & Maintenance plans
(ii)Facility Operating Time
(iii)Interacting with the
people (iv)Waste Screening
(v)Emergency Situation
(vi)Record Keeping
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Operation & Maintenance Plans:
- Although a transfer stations basic function as a waste consolidation and
transfer facility is straightforward, operating a successful station involves properly
executing many tasks.
-They should be written specifically for a particular facility and include
the following elements:
-
Facility operating schedules, including days of the week, hours each day
& holidays.
-
Staffing plan that lists duties by job title, minimum staffing levels
and typical work schedules.
-
Description of acceptable & unacceptable wastes.
-
Operating methods for each component of the facility & description of
maintenance procedure for each component.
- Employee training - Safety rules & regulations
- Recordkeeping procedures - Emergency Procedures
Facil ity Operating Hours:
- A transfer stations operating hours must accommodate the
collection schedules of vehicles delivering wastes to the facility.
- Operating hours need to consider the local setting of the transfer
station, including neighboring land uses, as well as the operating hours of
disposal sites collecting wastes from the transfer station.
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Record Keeping:
-Medium & large transfer stations typically record the following
informationas part of their routine works.
-Incoming Loads:date, time, company, driver name, truck number, origin
of load, fee charged.
- Outgoing Loads:date, time, company, driver name, truck number, type of
waste.
- Facility operating log:Noting any unusual events during the operating
day.
-Complaint Log: Noting the date, time, complaining party, nature of
thecomplaint.
-Accidents (or) releases: Details of any accident (or) waste releases into
the environment.
-Maintenance Records: For mobile and fixed equipments.
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Municipal Solid Waste Management
Unit IV
Off Site Processing
Syllabus:-
Processing techniques & Equipments Resource Recovery from solid
wastes Composting Incineration Pyrolysis Options under Indian
conditions.
1.Processing Techniques & Equipments
1.1 Purpose of Processing
- The processing of wastes helps in achieving the best possible benefit
from every functional element of the solid waste management (SWM) system and,
therefore, requires proper selection of techniques and equipment for every element.
- Essentially, the purposes of processing are:
(a)Improving efficiency of SWM system (e.g.) Shredding
(b)Recovering material for reuse
( c ) Recovering conversion products & energy
1.2
Various Techniques & Equipments:
(a)Mechanical Volume & Size reduction
(b)Component Separation
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-
Air Separation
-
Magnetic Separation
-
Screening
( c ) Drying & Dewatering
1.3 Mechanical Volume & Size Reduction
- Mechanical volume and size reduction is an important factor in the
development and operation of any SWM system.
- The main purpose is to reduce the volume and size of waste, as
compared to the original form, and produce waste of uniform size.
1.3.1 Volume Reduction (or) Compaction:
- Volume reduction (or) compaction refers to densifying wastes in
order to reduce their volume. The benefits of compaction are:
(a)
Reduction in the quantity of materials to be handled at the disposal site
(b)Improved efficiency of collection and disposal of wastes
( c ) Increased life of landfills
(d) Economically viable waste management system
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- The rejected material passes down a chute that is connected to a
bucket elevator, while the solid slurry passes out through the bottom of the
pulper tank and is pumped to the next processing operation.
1.4 Component Separation
- Component separation is a necessary operation in which the
wastecomponents are identified and either manually (or) mechanically to aid
further processing.
1.4.1 Air Separation
This technique has been in use for a number of years in
industrial operations for segregating various components from dry mixtures.
- Air separation is primarily used to separate lighter materials from
the heavier ones.
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Equipments used for Magnetic Separation
Suspended Magnet:
- In this type of separator, a permanent magnet is used to attract the
ferrous metal from the waste stream.
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- When the attracted metal reaches the area where there is no
magnetism, it falls away freely.
- This ferrous metal is then collected in a separate container.
Magnetic Pul ley:
- This consists of a drum type device containing magnets (or)
electromagnets over which a conveyor (or) a similar transfer mechanism carries
the waste stream.
- The conveyor belt conforms to the rounded shape of the magnetic
drum and the magnetic force pulls the ferrous material away from the falling
stream of solid waste.
1.4.3 Screening
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3. Composting
Composting is one of the important technologies for solid waste
management.
- Any organic material that can be biologically decomposed is
compostable.
- Today, composting is a diverse practice that includes a variety of
approaches, depending upon type of organic materials being composted and the
designed properties of final product.
The overall composting process can be explained as follows:
Organic matter + O2+ Aerobic bacteria Co2+ NH3+ H2O + other end products + Energy
3.1 Principles of Composting
- Decomposition and stabilization of organic waste matter is anatural phenomenon.
- Composting is an organized method of producing compost
manure by adopting this natural phenomenon.
- Composting can be carried out in two ways, aerobically
& anaerobically.
3.1.1 Aerobic Composting
- During composting, aerobic micro-organisms oxidize organic
compounds to Co2, Nitrite and Nitrate
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3.2Methods of Composting
-Manual composting was systemized by Howard and his associates.
-It was further developed by Acharya & Subramanyam and the
methods are conventionally referred as Indore and Bangalore methods of
Composting.
3.2.1
Bangalore Method
-This is an anaerobic method conventionally carried out in pits.
-
Formerly the waste was anaerobically stabilizes in pits where
alternate layers of MSW and night soil were laid.
- The pit is completely filled and a final soil layer is laid to prevent fly
breeding, entry of rain water into the pit and for conservation of the released
energy.
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- The material is allowed to decompose for 4 to 6 months after which
the stabilized material is taken out and used as compost.
3.2.2 Indore Method
- This method of composting in pits involves filling of alternate
layersof similar thickness as in Bangalore method.
- However, to ensure aerobic condition, the material is turned at
specific intervals for which a 60 cm strip on the longitudinal side of the pit is
kept vacant.
- For starting the tuning operation, the first turn is manually
given using long handled rakes 4 to 7 days after filling.
- The second turn is given after 5 to 10 days. Further turning
is normally not required and the compost is ready in 2 to 4 weeks.
Comparison of the methods:
- The Bangalore method requires longer time for stabilization of
thematerial & hence needs larger load space.
- The gases generated in this anaerobic process also pose smell &
odour problems.
- The Indore method on the other hand stabilizes the material
in shorter time & needs lesser land space.
- As no odourous gases are generated in this process, it is environment
friendly & hence commonly preferred.
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3.2.3 Windrow Composting
- The organic material present in Municipal Waste can be converted
into a stable mass by aerobic decomposition.
- Aerobic micro-organisms oxidize organic compounds to carbon
di oxide and oxides of Nitrogen and carbon from organic compounds is used as
a source of energy, while Nitrogen is recycled.
-Due to exothermic reactions, temperature of mass rises.
-In areas / regions were higher ambient temperatures are available,
composting in open windrows is to be preferred.
- In this method, refuse is delivered on a paved / unpaved open space
but leveled and well drained land in about 20 windrows with each window 3m
long x 2m long x 1.5m high with a total volume not exceeding 9.0 m3
- Each windrow would be turned on 6th
& 11th
days outside to
the centre to destroy insects larvae and to provide aeration.
- On 16th
day, windrow would be broken down and passed
through manually operated rotary screens of about 25mm square mesh to
remove the oversize contrary material.
- The screened compost is stored about 30 days in helps about 2m
x 1.5m high and up to 20m long to ensure stabilization before sales
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I ndian Standards for compost:
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3.2.4 Mechanical Composting
- Though manual methods are preferable in countries where labouriscomparatively cheap, processes are preferred where higher labour costs and
limitations of space exist.
- Mechanical composting plant is a combination of variousunits which perform specific functions.
- Solid waste collected from various areas reaches the plant site at avariable depending upon the distance of collection point.
- As the compost plant operates at a constant rate, a balancing storagehas to be provided to absorb the fluctuations in the waste input to the plant.
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- It is hence stored in large sized windrows for 1-2 months either at
the plants (or) farms.
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3.3Factors affecting Composting
(i)
Organisms
(ii)Use of cultures
(iii)Moisture
(iv)
Temperature
(v)C/N Ratio
(vi)Aeration
(vii)Addition of sewage & sewage sludge
Organisms:
- Aerobic composting is a dynamic system where in bacteria,actinomycetes, fungi and other biological forms are actively involved.
- The relative preponderance of one species over another depends
upon the constantly changing food supply, temperature and substrate conditions.
- When the temperature drops, actinomycetes & fungi are confinedto 5 to 15 cm outer surface layer.
- Thermophilic actinomycetes and fungi are known to grow well
in the range of 45 to 60C
Use of Cul tures:
- During the development of composting process, various innovatorscame forward with inoculum, enzymes claimed to hasten the composting process.
- Investigations carried out by various workers have shown thatthey are not necessary.
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- Under proper environment conditions, the indigenous bacteria
adopted to MSW rapidly multiply as compared to the added cultures.
- However, such inoculum will be required during composting of
industrial and agricultural solid waste which do not have the large mix ofindigenous bacterial population.
Moisture:
- The moisture tends to occupy the free air space between the
particles.
- Hence, when the moisture content is very high, anaerobic conditionset in.
- The composting mass should have a certain minimum moisturecontent in it for the organisms to survive.
-The optimum moisture content is known to be between 50 to 60%
-Higher moisture content may be required while composting straw
and strong fibrous material which is often the fibre and fills the large pore spaces.
Temperature:
-The aerobic decomposition of a gram mole of glucose releases 484to674 kilo calories energy under controlled conditions, while only 26 kcal arereleased when it is decomposed anaerobically.
- Under properly controlled conditions, temperatures are known to rise
beyond 70C in aerobic condition.
- This increased temperature results in increased rate of biologicalactivity and hence result in faster stabilization of materials.
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- The temperature range of 50C - 60
C is optimum for
nitrification and cellulose degradation.
- Thus, if the process is so controlled that the temperature is kept
between 50
C to 60
C for 5 to 7 days, destruction of pathogens and parasitescan be ensured.
Carbon to Ni trogen Ratio:
- The organisms involved in stabilization of organic matter utilizesabout 30 parts of carbon for each part of nitrogen and hence an C/N ratio of 30 ismost favorable.
- It has reported that optimum value to range between 2631 depending upon other environmental conditions.
- Whenever the C/N ratio is less than the optimum, carbon source
such as straw, sawdust, paper are added while if the ratio is to high, the
sewage sludge, slaughter house waste, blood are added as a source of nitrogen.
Aeration:
- It is necessary to ensure that oxygen is supplied throughout themassand aerobic activity is maintained.
- During the decomposition, the oxygen gets depleted and has tobe continuously replenished.
- This can be achieved either by turning of windrows (or) bysupplying compressed air.
- In case of artificial supplying, the quantity of air supply is normallymaintained at 12 cu m / day / kg of volatile solid.
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- It have shown that the optimum turning interval which will reduce
the cost and simultaneously maintain aerobic conditions in 5 days.
Addition of sewage & sewage sludge:
-The optimum C/N ratio for composting is 25-30.
-MSW in developed countries has a C/N ratio of nearly 80.
-To bring it down to the optimum value and to reduce the cost of
sewage sludge treatment, it is mixed with sewage sludge.
-MSW in India, has an initial C/N ratio of around 30 which does notneed blending.
4. Incineration
4.1 Definition
- Incineration process can be defined as an engineered process
using controlled flame combustion to thermally degrade waste materials inpresence of oxygen.
4.2Necessity of Incineration
-Waste volume reduced to less than 5%
-At sufficiently high temperature, and residence time, any
hydrocarbon vapour can be oxidized to carbon di oxide and water.
- Relatively simply devices capable of achieving very high removalefficiencies.
-
Heat can be recovered
-Most gases are burntwell designed systems
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- Solid as well as pasty and liquid materials can be fed into the furnace
for incineration at the same time.
- Through a high excess of air and through the constant addition of
supplemental fuel, thorough incineration is guaranteed.
-The hazardous waste and the incineration air is introduced into thesystem from the front side of the rotary kiln.
-
From the opposite end the slag and flue gas is being discharged.
-The following incineration temperatures are achieved:
Maximum furnace temperature in rotary kiln: 1050 degrees C
Maximum post-combustion temperature: 1300 degrees C
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Filtered out recyclable materials make for 15-20% of the initial amount of
waste, depending on its composition, and can be sold to the market, providing a
significant source of revenue.
-
The remaining waste stream is chipped into small pieces up to 50mmin diameter. In the dryer its moisture content is reduced down to 20% in order
to provide higher conversion results.
-
The properly prepared waste is finally collected in the storage bin.
Step 2: Pyrolysis of waste
-
The high-temperature pyrolysis process takes place in an indirectly heatedpyrolytic chamber (a retort) at 700-750%C in an oxygen-free environment, allowing
conversion of the waste into synthesis gas (90-98%) and a solid cocking residue, or
carbon char (2-10%), without any liquid tar fractions being formed.
-The specific temperature regime, continuously maintained in the process
chamber, eliminates any dioxins or furans in the carbon char residue thereby
allowing further use of this byproduct. Dioxins are contained in syngas only.
Step 3: Thermal Oxidizer
-
Syngas is mixed with air in the main burner and directed to the oxidizer for
combustion at 1200C.
-
Specific controlled conditions in the oxidizer ensure complete destruction of
dioxins and furans contained in the syngas and prevent their re-formation.
-The oxidized gasses have high thermal capacity and are partly utilized
by the system to maintain the temperature in the pyrolytic chamber, thereby
decreasing outside energy consumption (natural gas, or propane-butane) by 60%.
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Step 4: Energy Generation.
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As oxidized gas leaves the thermal oxidizer, its high temperature is heatexchanged to a waste heat boiler.
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Thermal energy captured from the oxidized gas is converted into high
temperature steam supplying energy to turbine generators which in turn
produce clean electric power
.Step 5: Pollution Control System.
-The cooled (flue gasses are passed through a multi-stage pollution control
system to be cleaned of harmful impurities and safely released into the
environment.
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Waste off gasses utilized for pyrolysis reactor heating are also directed
to the waste heat boiler, and, after being cooled, pass through a similar
depuration system.
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Municipal Solid Waste Management
Unit V
Disposal
Syllabus:-
Dumping of solid waste; sanitary landfills Site selection, design and
operation of sanitary landfills Leachate collection & treatment
1. Introduction
- The term landfill can be treated as synonymous to sanitary
landfill of Municipal Solid Waste, only if the latter is designed on the principle of
waste containment and is characterized by the presence of a liner and leachate
collection system to prevent ground water contamination.
- The term sanitary landfill has been extensively used in the past to
describe MSW disposal units constructed on the basis of dump and cover but
with no protection against ground water pollution.
- Such landfills do not fall under the term municipal solid waste
landfills
2. Sanitary Landfill
-The term landfill is used to describe a unit operation for final
disposal of Municipal Solid Waste on land, designed and constructed with the
objective of minimum impact to the environment by incorporating eight essential
components.
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4. Essential Components of a Landfill
The seven essential components of a MSW landfill are:
(a)
A liner system at the base and sides of the landfill which prevents migration of
leachate or gas to the surrounding soil.
(b)
A leachate collection and control facility which collects and extracts leachate
from within and from the base of the landfill and then treats the leachate.
(c)
A gas collection and control facility (optional for small landfills) which collects
and extracts gas from within and from the top of the landfill and then treats it or
uses it for energy recovery.
(d)A final cover system at the top of the landfill which enhances surface drainage,
prevents infiltrating water and supports surface vegetation.
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(e)
A surface water drainage system which collects and removes all surface runoff
from the landfill site.
(f)
An environmental monitoring system which periodically collects and analyses
air, surface water, soil-gas and ground water samples around the landfill site.
(g)A closure and post-closure plan which lists the steps that must be taken to close
and secure a landfill site once the filling operation has been completed and the
activities for long-term monitoring, operation and maintenance of the completed
landfill.
5. Site selection for Landfill
Selection of a landfill site usually comprises of the following steps, when a
large number (eg. 4 to 8) landfill sites are available:
(i)Setting up of a locational criteria
(ii)Identification of search area
(iii)Drawing up a list of potential sites;
(iv)
Data collection
(v)Selection of few best-ranked sites
(vi)Environmental impact assessment and
(vii)Final site selection and land acquisition.
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(f)
Public parks: No landfill should be constructed within 300 m of a public park.
A landfill may be constructed within the restricted distance if some kind of
screening is used with a high fence around the landfill and a secured gate.
(g)
Critical Habitat Area: No landfill should be constructed within critical habitat
areas. A critical habitat area is defined as the area in which one or more
endangered species live. It is sometimes difficult to define a critical habitat area. If
there is any doubt then the regulatory agency should be contacted.
(h)
Wetlands: No landfill should be constructed within wetlands. It is often difficult to define a wetland area. Maps may be available for some wetlands, but in
many cases such maps are absent or are incorrect. If there is any doubt, then the
regulatory agency should be contacted.
(i) Ground Water Table: A landfill should not be constructed in areas where
water table is less than 2m below ground surface. Special design measures be
adopted, if this cannot be adhered to.
(j) Airports: No landfill should be constructed within the limits prescribed by
regulatory agencies (MOEF/ CPCB/ Aviation Authorities) from time to time.
(k)Water Supply Well: No landfill should be constructed within 500 m of any
water supply well. It is strongly suggested that this locational restriction be abided
by at least for down gradient wells.
(l)Coastal Regulation Zone: A landfill should not be sited in a coastal regulation
zone.
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(m)
Unstable Zone: A landfill should not be located in potentially unstable zones
such as landslide prone areas, fault zone etc.
(n)
Buffer Zone: A landfill should have a buffer zone around it, up to a distance
prescribed by regulatory agencies.
(o)Other criteria may be decided by the planners.
I I Search Area
- To identify the potential sites for a landfill a search area has to bedelineated. The search area is usually governed by the economics of waste
transportation.
- It is usually limited by the boundaries of the municipality. Typically search
areas are delineated on a map using a search radius of 5 to 10 km, keeping the
waste generating unit as the centre.
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Alternatively, the search area may be identified by adopting a range of 5
km all around the built-up city boundary. One should start with a small search area
and enlarge it, if needed.
I I IDevelopment of a l ist of Potential Sites
-After demarcating the search area, as well as after studying the various
restrictions listed in the locational criteria, areas having potential for site
development should be identified.
- A road map may be used to show the potential sites that satisfy the
locational criteria. Preliminary data collection should be undertaken with an aim of
narrowing the list of sites to a few best-ranked sites.
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- In areas where land availability is scarce, degraded sites such as abandoned
quarry sites or old waste dump sites can be considered. Special design measures
are required for such sites.
I V Data Coll ection
Several maps and other information need to be studied to collect data within
the search radius. Some are discussed below.
(a)
Topographic Maps: The topography of the area indicates low and high areas,
natural surface water drainage pattern, streams, and rivers.
(b)Soil Maps: These maps, primarily meant for agricultural use, will show the
types of soil near the surface.
(c) Land Use Plans: These plans are useful in delineating areas with definite
zoning restrictions. There may be restrictions on the use of agricultural land or on
the use of forest land for landfill purposes.
(d) Transportation Maps: These maps, which indicate roads and railways and
locations of airports, are used to determine the transportation needs in developing a
site.
(e)
Flood Plain Maps: These maps are used to delineate areas that are within a 100
year flood plain. Landfill siting must be avoided within the flood plains of major
rivers.
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(f) Ground Water Maps: Ground water contour maps are available in various
regions, which indicate the depth to ground water below the land surface as well as
regional ground water flow patterns. Such maps should be collected from Ground
Water Boards or Minor Irrigation Tube well Corporations.
(i)
Rainfall Data: The monthly rainfall data for the region should be collected
from the Indian Meteorological Department.
(j)
Wind Map: The predominant wind direction and velocities should be collected
from the Indian Meteorological Department.
(k)Seismic Data: The seismic activity of a region is an important input in the
design of landfills Seismic coefficients are earmarked for various seismic zones
and these can be obtained from the relevant BIS code or from the Indian
Meteorological Department.
V Site Walk-over & Establ ishment of Ground Truths
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A site reconnaissance will be conducted by a site walk-over as a part of the
preliminary data collection. All features observed in various maps will be
confirmed.
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Additional information pertaining to the following will be ascertained from
nearby inhabitants:(a) Flooding during monsoons
(b) Soil Type
(c) Depth to G.W. Table (as observed in open wells or tube wells)
(d) Quality of groundwater and (e) Depth to bedrock.
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VI Prel iminary Boreholes and Geophysical I nvestigation
-At each site, as a part of preliminary data collection, one to two boreholes
will be drilled and samples collected at every 1.5m interval to a depth of 20m
below the ground surface.
-The following information will be obtained:
(i)Soil type and stratification
(ii)Permeability of each stratum
(iii)
Strength and compressibility parameters (optional)
(iv)
Ground water level and quality and
(v)
Depth to bedrock.
VI I Assessment of Publ ic Reaction
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The public/nearby residents should be informed of the possibility of siting
of a landfill in a nearby even as soon as a list of potential sites is developed. A
preliminary assessment of public opinion regarding all the sites in the list is
essential.-
Public reaction is less hostile if landfilling is done in an area already
degraded by earlier municipal waste dumps or other activities such as quarrying,
ash disposal etc.
VI I I Selection of Few Best-Ranked Sites
- From amongst a large number of sites, the selection of a final site will
emerge from a two -stage approach.
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(a)
Selection of a few best-ranked sites (usually 2 sites, sometimes 3) on the basis
of pathway and receptor related attributes.
(b)
Selection of final site on the basis of environmental impact assessment, social
acceptance and cost of disposal.
I X Environmental Impact Assessment (EIA)
-Wherever feasible, environmental impact assessment will be conducted for
two alternate sites (in exceptional circumstances up to 3 sites)
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The impact of the landfill on the following will be quantified: (a) Ground
water quality;
(a)Ground water quality; (b) Surface water quality; (c) Air quality gases, dust,
litter; (d) Aesthetics visual, vermin, flies; (e) Noise; (f) Land use alteration; (g)
Traffic alteration; (h) Drainage alteration; (i) Soil erosion; (j) Ecological impacts
X F inal Site Selection
- The final selection of the site from amongst the best-ranked alternatives
should be done by comparing:
(a)
The environmental impact;
(b)Social acceptance; and
(c)Transportation and landfilling costs.
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- The total landfill area should be approximately 15% more than the
area required for landfilling to accommodate all infrastructure and support
facilities as well as to allow the formation of a green belt around the landfill.
- There is no standard method for classifying landfills by their
capacity. However the following nomenclature is often observed in literature:
Small size landfill : less than 5 hectare area
Medium size landfill : 5 to 20 hectare area
Large size landfill : greater than 20 hectare area.
Landfill heights are reported to vary from less than 5 m to well above 30 m.
6.3 Layout
- A landfill site will comprise of the area in which the waste will be
filled as well as additional area for support facilities.
- Within the area to be filled, work may proceed in phases with only a
part of the area under active operation.
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The following facilities must be located in the layout:
(a)Access roads
(b)Equipment shelters
(c)Weighing scales
(d)
Office space
(e)
Location of waste inspection and transfer station (if used)
(f)Temporary waste storage and/or disposal sites for special wastes
(g)
Areas to be used for waste processing (e.g. shredding)
(h)
Demarcation of the landfill areas and areas for stockpiling cover material and
liner material
(i)Drainage facilities
(j)Location of landfill gas management facilities
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(k)
Location of leachate treatment facilities; and
(l)
Location of monitoring wells.
A typical site layout is shown below
- It is recommended that for each landfill site, a layout be designed
incorporating all the above mentioned facilities
7. Operation of a Landfill
- To secure public acceptability, landfill operations require careful
planning and determination of the extent of environmental effects.
- The basic factor influencing the planning of site operations is the
nature and quantity of incoming waste.
- The various aspects of operation of a landfill are as follows
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7.1 Methods of Filling
- Trench M ethod: This involves the excavation of a trench into which
waste is deposited, and the excavated material is then used as cover.
- Area Method:Wastes may be deposited in layers and so form terraces
over the available area. However, with this type of operation, excessive leachate
generation may occur.
- Cell Method: This method involves the deposition of wastes within pre-
constructed bounded area. It is now the preferred method in the industrialized
world, since it encourages the concept of progressive filling and restoration.
- Canyon / Depression: This method refers to the placing of suitable
wastes against lined canyon or ravine slide slopes. Slope stability and leachate gas
emission are critical issues for this type of waste placement.
7.2 Refuse Placement
- The working space should be sufficiently extensive to permit
vehicles to man oeuvre and unload quickly and safely without Impeding refusespreading, and allow easy operation of the site equipment.
- Depositing waste in thin layers using a compactor enables a high
waste density to be achieved.
- Various systems for monitoring the leachate level are in use, and are
mostly based on pipes installed prior to land filling.
- Placing pipes within a column or tyres may, however, offer some
protection.
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- At an early stage of site preparation, therefore, a number of
monitoring boreholes need to be provided around the site.
- However, the location, design and number of boreholes depend on
the size of the landfill, proximity to an aquifer, geology of the site and types of
wastes deposited.
8. Leachate Collection & Treatment
8.1 Leachate Control
-Leachate control within a landfill involves the following steps:
(a)
Prevention of migration of leachate from landfill sides and landfill base to the
subsoil by a suitable liner system
(b)Drainage of leachate collected at the base of a landfill to the sides of the landfill
and removal of the leachate from within the landfill.
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Three types of liner systems are usually adopted and these are describedhereafter:
(a) Single Liner System: Such a system comprises of a s