Solid Waste Generation and Handling

CHAPTER 2
SOLID WASTE GENERATION
WSEE 4192
Hawassa University
Institute of Technology
School of Bio-Systems & Environment Engineering

Course contents
2
Chapter1: Solid Waste Management
Chapter 2:Solid Waste Generation
Chapter3:Solid Waste Handling, Storage and Processing at the
Source
Chapter4:Collection Methods of Solid Waste
Chapter5:Solid Waste Separation, Processing and
Transformation
Chapter6: Solid Waste Transport and Transferand Disposal

Chapter 2:Solid Waste Generation
2.1 Introduction
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 The characteristics, quantities, volume and composition of
solid waste generated may differ from one country to
another and between urban and rural areas.
 It depends mainly upon the customs, climate, living
conditions and economic standard of the area.
 As a consequence, if solid waste management is to be
accomplished in an efficient and orderly manner, the
fundamental aspects and relationships involved must be
identified, adjusted for uniformity of data, and understood
clearly.

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 Aesthetic, land use, health,
water pollution, air pollution,
and economic considerations
make proper storage,
collection and disposal of
solid wastes municipal and
individual functions that must
be taken seriously.
 Indiscriminate dumping of
solid waste and failure of the
collection system in a
populated community would
soon cause many health
problems.
Introduction…
Solid Wastes Polluting a River

2.2 Functional elements of solid waste
management
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 The activities involved with the management of solid wastes from
the point of generation to final disposal have been grouped into six
functional elements:
1. Waste generation
2. On-site handling, storage, and processing
3. Collection
4.Transferand transport
5. Processing and recovery and
6.Disposal.
 By considering each functional element separately it is possible to
identify the fundamental aspects and relationships involved in each
element and to develop where possible, quantifiable relationships for
the purposes of making engineering comparisons analyses, and

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management…
Interrelationship of functional elements comprising a solid waste management System

management…
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 Waste generation: Those activities in which materials are
identified as no longer being of value and are either thrown away
or gathered together for disposal.
 On- site handling, Storage, and processing: Those activities
associated with the handling, storage, and processing of solid
wastes at or near the point of generation.
 Collection: Those activities associated with the gathering of solid
wastes and the hauling of wastes after collection to the location
where the collection vehicle is emptied.
 Transfer and transport: Those activates associated with the
transfer of wastes from the smaller collection vehicle to the larger
transport equipment and the subsequent transport of the wastes,
usually over long distance to the disposal site.

 Processing and recovery: Those techniques, equipment and
facilities used both to improve the efficiency of the other
functional elements and to recover usable materials, conversion
products, or energy from solid wastes.
 Disposal: Those activities associated with ultimate disposal of
solid wastes including those wastes collected and transported
directly to a landfill site, semisolid wastes (sludge) from
wastewater treatment plants incinerator residue compost, or
other substances from the wires solid waste processing plants
that are of no further use.
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management…

2.3. Generation Rate of Municipal Solid
Waste
 Determination of the generation rate of solid waste is important
to obtain data in order to determine waste volume and for
subsequent solid waste management.
 In addition to knowing the source and composition of solid
waste, it is equally important to have uniform units of expression.
• Household waste (kg/capita/day)
• Commercial waste (kg/x/day where x can be m2 of floor area
of commercial establishment, unit volume or dollar in sales, the
number of employees, etc.)
• Institutional waste (kg/x/day where x can be the number of
students, m2 of the area of park or public place, number of
visitors, etc.)
• Industrial waste (kg/x/day where x can be unit volume or dollar
of production output, m2 of floor area, the number of
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2.3. Generation Rate of Municipal Solid Waste....
 Waste quantities are usually estimated on the basis of data
gathered by conducting a waste characterization study, using
previous waste generation data or some combination of the two
approaches.
 Load-Count Analysis: In this method, the number of individual
loads and the corresponding waste characteristics (types of
waste, estimate volume) are noted over a specified time period. If
scales are available, weight data are also recorded.
 Weight -volume analysis: measuring the volume of the truck and
weight of each load will give sample data.
 Materials Mass Balance Analysis: The only way to determine the
generation and movement of solid wastes with any degree of
reliability for each generation source, such as an individual home
or a commercial or industrial activity. In some cases, the
materials balance method of analysis will be required to obtain
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Methods of Estimate MSW
Quantities

Methods of Estimate MSWQuantities…
Preparation of Materials Mass Balances:
 Draw a system boundary around the unit to be studied. It will be
possible to simplify the mass balance computations.
 Identify all the activities that cross or occur within the boundary and
affect the generation of wastes.
 Identify the rate of waste generation associated with each of these
activities.
 Using appropriate mathematical relationships, determine the
distribution which is about 40 to 50 percent rubbish , 20 to 30
percent wood and related products, and 20 to 30 percent
miscellaneous wastes (painted or contaminated lumber, metals tar-
based products, plaster, glass, white goods, asbestos and other
insulation material, and plumbing, heating and electrical parts).
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2.3. Generation Rate of Municipal Solid Waste....

2.3. Generation Rate of Municipal Solid
Waste…
 Solid waste generation rates estimate the amount of waste
created by residences or businesses over a certain
amount of time (day, year, etc.).
 Waste generation includes all materials discarded,
whether or not they are later recycled or disposed in a
landfill.
 Waste generation rates for residential and commercial
activities can be used to estimate the impact of new
developments on the local waste stream.
 They may be useful in providing a general level of
information for planning purposes.
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2.4. Factors affecting MSWGeneration Rates
1. Effect of source reduction , Reuse and Recycling Activities on Waste
Generation
 Source Reduction: Waste reduction may occur through the design,
manufacture, and packaging of products with minimum toxic content,
minimum volume of material, and longer useful life.
- Reduce office paper waste by implementing a formal policy to
duplex all draft reports and by making training manuals and
personnel information available electronically.
- Improve product design to use less materials.
-Redesign packaging to eliminate excess material while maintaining
strength.
-Work with customers to design and implement a packaging return
program.
- Switch to reusable transport containers.
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2.4. Factors affect MSWGeneration Rates…
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 Waste management aims
to:
 Minimize the amount of
waste generated (source
reduction)
 Recover waste materials
and recycle them
 Dispose of waste safely
and effectively
 So urce re ductio n is the
pre fe rre d appro ach

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2.4. Factors affect MSWGeneration
Rates…
Reuse:
Cleaning and using the material
over and over again
Increasing the lifespan of the
product.

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Reuse…

 Recycling is collecting materials
that can be broken down and
reprocessed to manufacture new
items.
 Household Recycling products
are: Paper Products, Glass,
Aluminum, Steel and Some
plastics
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18
Benefits of Recycling

Rates…
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Recycling…

2. Effect of public Attitudes and legislation on waste generation
 Public Attitudes - significant reduction in the quantities of solid
wastes generated occur when and if people are willing to change
of their own volition- their habits and lifestyles to conserve
natural resources and to reduce the economic burdens
associated with the management of solid wastes.
 A program of continuing education is essential in bringing about
a change in public attitudes.
 Legislation Perhaps the most important factor affecting the
generation of certain type of wastes is the existence of local,
state, and federal regulations concerning the use of specific
materials.
 Encouraging the purchase and use of recycled materials by
allowing a price differential (typically 5 to 10 percent) for recycled
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Rates…
3. Effect of Geographic and physical factors on waste Generation
 Geographic and physical factors that affect the quantities of
waste generated and collected include:
a. geographical location – related primarily to the different climate
that can influence both the amount generated and collection
operation.
b. season of the year
c. frequency of collection
d. characteristics of population
e. extent of salvage and recycling.
f. legislation
g. public attitude
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CHAPTER 3
SOLID WASTE HANDLING, STORAGE AND
PROCESSING AT THE SOURCE

3.1. Introduction
 The handling, storage and processing of solid wastes at the
source before they are collected is the second of the six
functional elements in the sold waste management system.
 Waste handling and sorting involves the activities associated
with management of wastes until they are placed in storage
containers for collection.
 Handling also encompasses the movement of loaded containers
to the point of collection.
 Sorting of waste components is an important step in the
handling and storage of solid waste at the source. For example,
the best place to separate waste materials for reuse and
recycling is at the source of generation.
 Households are becoming more aware of the importance of
separating newspaper and cardboard, bottles/glass, kitchen
wastes and ferrous and non-ferrous materials.
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Introduction…
24
Segregation at source MSW Waste
minimization
Waste collection from source to segregation centers
Waste segregation into degradable to non- degradable
Non degradable wastes Organic waste size reduction
Recycling plant aerobic
composting
Agricultural land, gardens etc

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3.2. On Site Handling of Solid Waste
 On-site handling methods and principles involve public attitude,
individual belief and ultimately affects the public health.
 It is an activity associated with the handling of solid waste until
they are placed in the containers used for their storage before
collection. This may take place at any time before, during or after
storage.
 Importance of on-site handling of solid waste:
- reduce volume of waste generated
- alter physical form
- recover usable materials
 On- site handling methods: Segregation, shredding, grinding and
composting.

 Segregation of wastes into degradable and non-degradable wastes
is to be done to recover or divert non-degradable wastes (electric
items, plastics, tyres etc.) and degradable items (wood, textiles
etc.) to its recycling plant and if possible, it can be reused.
 It is a tedious process which therefore needs labor. Magnets can
also be used to segregate ferrous metals.
 This process will help in reducing the amounts of waste going for
composting and also earns money through selling wastes to
recycling plant.
 Shredding or Pulverizing: this process involves in size reduction of
organic wastes before it goes for composting. This process
reduces the overall volume by 40%.
 It will increase surface area availability for bacterial activity for
decomposition and facilitates easy handling of moisture content
and aeration.
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3.2. On Site Handling of Solid Waste…

 Composting: Solid waste
composting for use as a soil
amendment, fertilizer or growth
medium.
 Aerobic composting is one of the
cheapest and easiest methods that
are being available for MSW.
 There are two fundamental types of
composting techniques:
1. Open or windrow composting: a
slower process conducted outdoors
with simple equipment.
2. Enclosed system composting: where
composting is performed in a
building, tank, box, container or
vessel.
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Composting…

Duration of composting
 Composting is completed when the compostable materials have
entirely turned into humus.
 Compost stability can be tested by re-wetting the material to see
whether it heats up again, thus revealing still un-composted
materials in the pile.
 Most aerobic composting systems include a period of active
composting, generally from 21 to 60 days, and a period of curing,
generally from 6 to 24 months.
 Composting can be accelerated by intensive aeration and
inoculation of the piles with suitable bacteria. More land is required
when the period of composting is longer, as the throughput of
waste is slower. In places where land for sitting is scarce, sound
practice may entail selection of more intensive management
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Majorcomposting factors to be considered:
 Sitting: Compost facilities must be reasonably close to the input stream
and potential users should meet the needs of the nearby community.
 Input stream: Source-separated organics are best. However, in most
developing countries, this is not always possible. Mixed waste can be
processed to yield acceptable compost.
 Selection of appropriate technology: The technology chosen must be
adequate for the input stream and level of economic development of the
country.
 Scale: A smaller-scale facility often facilitates careful composting and
formation of a good product.
 Market development: Governments generally need to stimulate the
compost market. Quality standards are an important marketing element.
 Existing compost practices using compost from dumps and garbage
dump farming: These traditional activities, while often dangerous could, in
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3.3. On Site Storage of Solid Waste
 The first phase to manage solid waste is at home level. It requires
facilities for temporarily storing of refuse on the premises.
Individual house holder or business owner has responsibility for
onsite storage of solid waste.
 For individual homes, industries, and other commercial centers
proper onsite storage of solid waste is the beginning of disposal.
Because un-kept or simple dumps are sources of nuisance,
flies, smells and other hazards.
 Factors that should be considered in the on-site storage of solid
waste are:
1. the type of container to be used,
2. the location where the containers to be kept,
3. public health,
4. the collection method and time.
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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 or receptacles can be constructed from galvanized iron
sheet or plastic materials. They should have tightly fitting covers.
 They must be of such size that, when full, they can be lifted
easily by one man. They should be located in a cool place on
platforms at least 30 centimeters above ground level.
 After putting in garbage, they should be kept covered. The bins
must be emptied at least daily and maintained in clean
conditions.
 An adequate number of suitable containers should be provided
with proper platforms with receptacles stand. The number may
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3.3. On Site Storage of Solid Waste…

Storage container…..
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public garbage bins
Waste container
attached to wall
Waste container in the
shape of a dolphin.
Bins in fast food restaurants
are marked to thank the
customers for disposing of
their own garbage A typical office trash can
Containers

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Storage container…
High capacity
trash bin for solid
waste collection

Storage container…..
 Certain public areas have
waste bins which are placed
alongside paths frequently
walked by visitors.
 This encourages people to
avoid littering, as littering
creates an unhealthy and
aesthetically unpleasant
Social environment.
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Bins in public areas
Waste containers

2. Containersize (capacity)
 Consideration should be given for the size of the loaded
container that must be hauled the collection vehicle or to the
disposal site. Therefore, container size for:
• ash up to 80 to 128 litter
• mixed refuse should not exceed 120 to 128 litter
• rubbish up to 200 liter
• office waste is 10-20 liter
• kitchen waste is 40 liter
• garbage is 48 to 80 liter
 Plastic liners for cans and wrapping for garbage reduce the need
for cleaning of cans and bulk containers, keep down odors, rat
and fly breeding.
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 Galvanized metal is preferable for
garbage storage because it is
resistant to corrosion.
 Plastic cans are light in weight
but are easily gnawed by rats.
 Bulk containers are
recommended where large
volumes of refuse are generated,
such as at hotels, restaurants,
apartment houses, shopping
centers.
 A concrete plat form provided
with a drain to an approved
sewer with a water faucet at the
site to facilitate cleaning.
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Containers for recycling
Garbage containers

3.4. On Site Processing of Solid Waste
 On-site processing is intended to improve disposal options, recover
valuable resources, and prepare materials for recovery as new products or
energy.
 Factors that should be considered in evaluating on-site processing are
capabilities, reliability, environmental effects, ease of operation, safety to
workers and the local community, efficiency, economics, and, aesthetics
(noise, odors, litter, increased traffic).
 A number of processing technologies have been developed for solid waste
management and one of the jobs of the engineer is to select and design
the most sustainable and cost effective for a given community.
 Some of the objectives of solid waste processing include:
• Component separation (hand sorting, screening, magnetic separation, air
classification for lighter materials such as paper and plastic).
 Volume reduction (baling, shredding, incineration)
 Size reduction (Shredding, grinding)
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