GONDAR UNIVERSITY
INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL AND WATER RESOURCES
ENGINEERING
CIVIL ENGINEERING
Environmental Engineering
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CHAPTER SIX: Solid and Hazardous
Waste Management
6.1 Overview
 Solid Waste is defined as anything non-liquid and non-gaseous in
terms of by product that is produced because of any human activity
and can produce any detrimental impact on environment
 Solid wastes are all the wastes arising from human and animal
activities that are normally solid and are discarded as useless or
unwanted.
 Solid waste as, "any discarded, rejected, abandoned, unwanted or
surplus matter, whether or not intended for sale or for recycling,
reprocessing, recovery or purification by a separate operation from
that which produced the matter or anything declared by regulation or
by an environment protection policy to be waste"
6.2 Main categories of solid waste
 Municipal
Solid Waste : mainly the household waste include
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commercial waste and institutional waste.
 Agriculture waste : Wastes and residues resulting from diverse
agricultural activities include plant residue and animal waste.
 Industrial waste : comprises waste from industrial processes
 Hazardous waste: Wastes or combination of wastes that pose a
substantial present or potential hazard to human.

Medical waste: includes hazardous (clinical waste) and nonhazardous waste. Clinical wastes are any waste consist human
tissue, blood or other body fluids, excretion include infectious waste.
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6.3 Environmental Impact of Solid Waste
Disposal on Land
When solid waste is disposed off on land in open dumps or
in improperly designed landfills (e.g. in low lying areas), it
causes the following impact on the environment.
a. Ground water contamination by the leachate generated by
the waste dump
b. Surface water contamination by the run-off from the
waste dump
c. Bad odor, pests, rodents and wind-blown litter in and
around the waste dump
d. Generation of inflammable gas (e.g. methane) within the
waste dump
f. Bird menace above the waste dump which affects flight of
aircraft
g. Fires within the waste dump
h.Erosion and stability problems relating to slopes of the
waste dump
i. Epidemics through stray animals
j. Acidity to surrounding soil and
k. Release of green house gas
6.4 Solid Waste Management
 Solid waste management may be defined as
the discipline
associated with the control of generation, storage, collection,
transfer and transport, processing and disposal of solid waste.
 It is one among the basic essential services provided by municipal
authorities in the country to keep urban centers clean.
 In its scope, SWM includes all administrative, financial, legal,
planning, and engineering functions involved in solution to all
problems of solid wastes.
6.4 Objective of Solid Waste Management
 Is to protect the health of the population.
 Is to promote environmental quality and
sustainability, support economic productivity and
employment generation.
 Is to reduce the quantity of solid waste disposed off
on land by recovery of materials and energy from
solid waste.
 Results in lesser requirement of raw material and
energy as inputs for technological processes.
6.5 Characterization of solid waste
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 The solid waste is a mixture of heterogeneous matter and its
composition differs with the origin, i.E., Residential waste are
different from commercial waste and industrial waste are different
from agricultural waste
 In order to decide about the handling of solid waste at all the
stages of solid waste management (i.E., Storage, collection,
processing and recovery and disposal, it is necessary to know the
exact nature of wastes)
 Characterization of solid waste is a difficult task due to:
 Heterogeneity of the waste
 Spatial and temporal variations
The purposes of characterization SW can be:
 To classify waste as hazardous or non-hazardous waste according to
national regulation
 To document adherence to specified quality criteria for recycled
materials
 To
determine waste generation rates for residential waste to
forecast of waste quantities based on to population growth
 To characterize waste quantity and composition for the design of
a waste incinerator
 Effectiveness of waste reduction, recycling programs or bans on
the disposal of certain materials
 Size, capacity and design of facilities to manage the waste
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Information on SW characteristics is also
important in determining the:
 Types of collection services
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 Types of collection vehicles
 Types of processing facilities
 Disposal methods
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Factors That Contribute To the Solid
Waste Problem
Factors That Contribute To the Solid
Waste Problem
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 Rapid Urbanization
 Urban development
 New township development
 Development of housing estate
 Industrial
 Changing Lifestyle
 Standard of living
 Buying power
 Consumption Patterns
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Inadequate government
policy
 Lack of enforcement
 No uniformity in
regulations
 No comprehensive laws and
regulations
 Lack of Disposal area
Spiraling population
growth rate
 High Population Growth
rate
 Internal migration of
population
 External migration of
population
Public indifference

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Propensity of the people to
generate waste and just throw
it anywhere

Lack of appreciation of the
importance of waste
avoidance/ reduction,
composting

Inefficient collection of
garbage

Non-operation of a good
disposal facility

Consumption is greatly increasing in developing nationsRising standard of living, more packaging, poor-quality goods.
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
Wealthy consumers often discard items that can still be used.

some people support themselves by selling items they scavenge
from dumps.
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Functional elements of WMS
This may be described as the activities associated with the
management of solid wastes from the point of generation to the
final disposal point
1. Waste generation
2. Waste handling and separation, storage and processing at
source
3. Collection
4. Separation, processing and transformation of solid waste
5. Transfer and transport
6. Disposal
6.6 Functional elements of WMS
6.6 Functional elements of WMS
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1. Waste generation
Activities in which materials are identified as no
longer useful and are either thrown away or
gathered together for disposal.
Waste generation
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Methods Used to Determine Generation Rate…
Materials Balance Analysis for the determination of SW Generation Rate
A detailed material balance analysis for each generation source, such as an
individual home or a commercial and industrial activity is made to determine
generation rate
As compared to load count analysis, this method gives relatively accurate value of
generation rates
Steps to follow for material balance analysis
Draw a system boundary around the unit to be studied
Identify all activities that cross or occur within the boundary and affect
generation rate
Give generation rate in each activity
Determine the quantities of waste generated, collected and stored by using a
material balance
Fig.: Material balance analysis sketch
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 Materials Balance Analysis for the determination of SW Generation Rate
Example-2
1. A cannery (where food/fruits are canned) receives on a given
day
i) 12 tons of raw produce
ii) 5 tons of cans
iii) 0.50 tons of cartons
iv) 0.30 tons of miscellaneous materials
2. As a result of internal activity
i. 10 tons of product are produced, remainder are discharged t o
sewer
ii. 4 tons of cans are stored, remainder used
iii) 3% of cans and cartons are damaged and incinerated
respectively, remainder used
iv) 75% of miscellaneous materials become paper waste and
incinerated, remainder is disposed of
3. Determine the generation rate of solid wastes
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Solution
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oCans used in product = (1 – 0.03) ton = 0.97 ton
oCartons incinerated = (0.03) (0.5 ton) = 0.015 ton
Cartons used in product = (0.5 – 0.015)ton = 0.485ton
oMiscellaneous incinerated = (0.75) (0.3 ton) = 0.225 ton
Miscellaneous disposed of = (0.3 – 0.225) ton = 0.075 ton
oTotal incinerated (0.015 + 0.225)ton = 0.240 ton
oTotal produce = (10 + 0.97 + 0.485) tons = 11.455 tons/d
Comment
oThis simple example was presented to illustrate some of the computations involved in the
preparation of a materials-balance analysis. If the internal processing activities are more
complex, the amount of work involved in arriving at a materials balance obviously could
become prohibitively expensive
Functional elements of WMS
2. Waste handling and separation, storage and processing at
source
 Activities related to management of waste until they are put
in storage containers for collection
 Handling:-Movement of loaded containers to point of
collection
Functional elements of WMS
Separation
 this is grouping waste into various categories
depending on the nature of it e.g. Organics, Paper,
Bottles and Cans etc.
 Important step in recovering materials for recycling
and reuse, and storage at source
Example-3: Home separation and delivery to drop-off
centers
A community of 1200 homes cannot pay for the initial and
operating costs of the recycling collection vehicles that were
to be used. Instead, residents are to haul recycling containers
to a drop-off center operated by the community. Calculate
the number of cars from which recyclable materials must be
unloaded per hour at the recycling drop-off center. Assume
the center is open for eight hours per day, two days per week
and that 40% of the residents will deliver recycling
containers. Also assume that 75% of the participants will
take their separated materials to the drop-off center once per
week and that the remaining 25% of the participants will
bring their separated materials to the drop-off center once
every 2 week
Solution
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Functional elements of WMS
 Storage :-On site storage important for the following
reasons:
 Public health concerns
 Aesthetic considerations
 Processing at source
◦ Involves activities such as compacting and yard composting
I. Hauled Container System (HCS)…
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 The container is carried by the truck
 A variation (exchange container mode) is start with an empty
container
 Suited for the removal of wastes from sources where the rate of
generation is high b/s large containers are used
Hauled container system (conventional mode)
The emptied containers are brought back at the same
locations, from where they were picked up
Fig.: HCS (Conventional mode)
Hauled Container System (Exchange container mode)
 Storage containers are hauled to an MRF(material recovery
facility), transfer station or disposal site, emptied and returned to a
different location
 Works best when the containers are of a similar size
 Driver must begin the collection route with an empty container on
the vehicle to be deposited at the first collection site
Fig.: HCS (Exchange container mode)
Stationary Container System (SCS)….
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 Container size and utilization are important
 The container remains in the vicinity where waste is generated
 The waste is unloaded into a bigger truck
 A large container is an integral part of the truck
 The collection vehicles are usually compactor trucks
 When fully loaded from multiple waste containers, the truck travels
to and from the landfill as opposed to the waste container
Two types:
(i) With mechanically loaded vehicles
(ii) With manually loaded vehicles
Analysis of Hauled Container Collection System
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Fig.: Time spent in various activities
Con…
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 This average total time spent per trip (hrs)
 Pc average time spent in pick up of filled container
 H average haul time to disposal and back (hr/trip)
 S average time spent at disposal site(hr)
 Uc average time spent in redeposit of the emptied container (hr/trip)
 dbc average haul time spent in driving between two container location
 Let W be the fraction time spent in offsite activity then
Analysis of Hauled Container Collection System
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t1= time to travel from garage to work area
t2 = time to travel from work area to garage
H= total working hour per day
Nd= number of trip per day
Functional elements of WMS
3. Collection
includes gathering of solid wastes and recyclable materials ,
transport of these to the location where collection vehicle is
emptied
location could be
processing facility
transfer station
landfill site etc
3. Collection
Analysis of Collection Systems
 Analysis refers to determining
 The number of vehicles required
 Capacity of vehicles required
 Crew size required
 Labor required
 Length of workday/week required
 Cost involved in a particular collection system
 For the purpose of analysis, the collection activities may be broken down into
different unit operations
 Pick-up time
 Haul time
 On Site time
 Off-Route time
 Time per Trip
 Container capacity, waste volume generated
 Volume compaction factor
Analysis of Collection Systems….
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The activities involved in the collection of SWs can be resolved
into 4 unit operations:
1 . Pickup Time
The time spent in pickup of container or
The time required to load the collection vehicle
Denoted by ‘Pc’
 PHCS
Time spent driving to the next container
The time spent picking up the loaded container
Time required to re-deposit the container after it has been emptied
 PSCS
Time spent loading the vehicle, beginning with the first container and
ending when the last container has been loaded
Analysis of Collection Systems….
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2. Haul Time (h)
Denoted by 'h'
 HCS: the time required to reach the location where the waste will be
emptied
 SCS: the time required to reach the location where the full vehicle will be
emptied and continuing until the truck arrives at the location
It is time for transporting SW to disposal site and coming back
Where: n is the number of trips from the collection route to the tip
site
b is the travel time from the collection route to the disposal site (oneway travel time only)
3. On-site Time (s)
oThe time spent at the disposal site (landfill, transfer station, processing
facility)
 Includes unloading time and the waiting time
 For multiple trips, the on-site time becomes ns
 Denoted by 's‘
 A fixed value for each trip to the disposal site
Analysis of Collection Systems….
4. Off-Site Time (W)
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 Non-productive activities (Check in, check out, relief time, dispatch
time, route retracing, meeting and breaks, Lunch,)
 It is denoted by 'W‘
 It is time spent on activities that are non-productive from the point
of view of the overall collection operation.
 They may be (a) necessary and (b) unnecessary
 The off-route time factor varies from 0.1 to 0.25; average of 0.15 is
representative of most SW operations
5. Time per Trip
It is denoted by 'T‘
It is time taken for one trip from container location to disposal site and
back to the next container location
It is equal to the sum of all above unit operations = (1 – 4 above)
Analysis of Hauled Container Collection System….
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 Also haul time to disposal site depends upon the speed and distance
traveled
 It can be expressed as:
Similarly,
Collection and Disposal Time
The time required for the collection and disposal of
one load (either full or partial) during the working
day can be computed as:
L1 = pickup time + haul time + on-site time + offroute time
The truck comes from the storage yard, collects the
SW needed to fill it, drives to the disposal area and
unloads and then returns to the storage yard
If a full working day is not required to collect one
load, what happens to the vehicle after it has been
unloaded?
Example6.3: Analysis of hauled container system.
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Solid waste from a new industrial park is to be collected in large
containers (drop boxes), some of which will be used in
conjunction with stationary compactors. Based on traffic studies
at similar parks, it is estimated that the average time to drive
from the garage to the first container location (t1) and from the
last container location(t2) to the garage each day will be 15 and
20 min, respectively. If the average time required to drive
between containers is 6min and the one- way distance to the
disposal site is 15.5 km (speed limit:55km/h), determine the
number of containers that can be emptied per day, based on an
8h work day. Assume the off-route factor, W, is equal to 0.15.
Use Pc+uc=0.4/trip
S=0.133h/trip
a=0.016h/trip
b=0.018h/trip
4. Separation, Processing and Transformation
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Functional elements of WMS
4. Separation, Processing and Transformation
 Occurs primarily in locations away from the source of waste
generation.
 Sorting of commingled (mixed) wastes usually occurs at a materials
recovery facility, transfer stations, combustion facilities, and disposal
sites.
◦ Sorting often includes
Transformation processes are
used
 the separation of bulky items,
 separation of waste components by size using screens, ◦ to reduce the volume,
weight, size or toxicity of
 manual separation of waste components,
waste requiring disposal
 separation of ferrous and non-ferrous metals
without resource recovery.
 Waste processing is undertaken:
◦ to recover conversion products and energy
 transform organic fraction by
 biological process - aerobic composting
 chemical process – combustion/incineration
 size reduction by
shredding
 volume reduction by
compaction and combustion
Functional elements of WMS
5. Transfer and Transport
 The functional element of transfer and transport involves
two steps:
i. the transfer of wastes from the smaller collection vehicle to
the larger transport equipment and
ii. the subsequent transport of the wastes, usually over long
distances, to a processing or disposal site. (i.e when disposal
sites are far from point of collection)
 The transfer usually takes place at a transfer station.
Functional elements of WMS
6. Disposal
◦ Land filling or Dumping
◦ Incineration/combustion
 Combustion is the controlled burning of waste in a
designated facility to reduce its volume and, in some cases,
to generate electricity.
 These activities are used to manage waste that cannot be
prevented or recycled.
6.7 Integrated Solid Waste Management
 ISWM is the selection and application of
suitable
techniques,
technologies
and management
programs
covering all types of solid wastes from all sources to achieve
the twin objectives of:
 waste reduction (produce ‘more with less’)
 effective management of waste still produced after waste
reduction.
 An effective ISWM System considers how to prevent, recycle,
and manage solid waste in ways that most effectively protect
human health and the environment
◦ refers to the strategic approach to sustainable management of
solid wastes covering all sources and all aspects, covering
generation, segregation, transfer, sorting, treatment, recovery
and disposal in an integrated manner, with an emphasis on
maximizing resource use efficiency
iii. Integrated Solid Waste Management
ISWM activities and hierarchy are:
1. Waste prevention/ Source reduction
2. Recycling
3. Waste transformation(composting/ combustion)
ISWM hierarchy
4. Landfilling
iii. Integrated Solid Waste Management
ISWM: Waste Prevention
1. Prevent waste from being generated
Strategies:
 less packaging
 packaging with minimum toxic content
 design products to last longer
 reuse products and materials, repair broken items
 Helps to reduce handling, treatment, and disposal costs and
ultimately the production of methane
 The modern concept of waste mini is based on the three ‘R’s
iii. Integrated Solid Waste Management
ISWM: Recycling
Process involves
◦ Collecting, reprocessing
and/or recovering certain
waste materials (e.g. glass,
paper, metals, plastics) to
make new materials or
products.
Environmental and economic
benefits
 jobs and income
 supply raw material to
industry
 reduce demand on
resources and amount of
waste requiring disposal
by landfilling
ISWM: Waste
transformation
Involves:
 physical, chemical, or biological
alteration of waste.
 These techniques are applied to:
Improve efficiency of SWM
systems and operations
recover conversion products
(e.g. compost) and energy (heat
and combustible biogas)
results in reduced use of landfill
capacity
iii. Integrated Solid Waste Management
ISWM: Landfilling
Activities used to manage waste that cannot be prevented or
recycled
 Waste is placed in properly designed, constructed and
managed land fills
 Methane recovery (biogas)
 Represents the least desirable means of dealing with society’s
wastes
Suggested Priorities for Integrated Waste
Management
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iv. Planning for ISWM
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 Planning is the first step in designing or improving a waste
management system.
 Waste management planners should take into consideration
institutional, social, financial, economic, technical, and
environmental factors.
These factors vary from place to place.
 Based on these factors, each community has the challenge of
selecting the combination of waste management activities
that best suits its needs.
iv. Planning for ISWM
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iv. Planning for ISWM
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 Selection of a proper mix of alternatives and technologies to
meet changing local waste management needs while
meeting legislative mandates
 Proper mix of alternatives and technologies considerations
◦ proper mix b/n
 amount of waste separated for reuse and recycling
 amount of waste composted
 amount of waste combusted
 amount of waste to be disposed off in landfills
Waste Disposal Options
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The waste management sector follows a generally accepted
hierarchy.
The earliest known usage of
the ‘waste management
hierarchy’ appears to be Ontario’s Pollution Probe in the early
1970s.
The hierarchy started as the ‘three Rs’ — reduce, reuse,
recycle — but now a fourth R is frequently added — recovery.
The hierarchy responds to financial, environmental, social and
management considerations.
Waste Disposal Options
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Methods of solid waste disposal
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Sanitary Landfill
 Sanitary landfill is an effective and proven method for a
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permanent disposal of refuses.
 Can be used in any community where sufficient suitable
land is available.
 The sanitary landfill method of solid waste disposal
consists basically of four steps:
 Depositing of refuse in planned and controlled
manner
 Compacting the refuse in thin layer to reduce its
volume
 Covering the refuse with a layer of earth
 Compacting the earth cover
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Methods of solid waste disposal
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Example
Landfill area requirement: Determine the area required for a
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new landfill site with a projected
life of 20 years for a
population of 150,000 generating 2.5 kg per household per
day. Assume the density of waste is 400 kg/m3 and 5
persons per household. A planning restriction limits the
height
of
the
landfill
to
10m.
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2. A residential area of about 40ha contains 400 single family
residences and 8ha with multiple-family units housing 400
people. With two curb-side pick ups per week, how many trips on
each collection day would one packer truck need to make to serve
this area if its capacity is 5 tones ? Assume four residents per
single-family unit. Assume the residential per capital waste
generation is 1.1 kg/day.
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