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ENVS 411: SOLID WASTE MANAGEMENT & HAZARDOUS WASTE
LECTURE 1; 25TH SEPT 2018
The term usually relates to materials by human activity and the process is generally undertaken
to reduce the effect on health, the environment or aesthetics
...
Waste
management is a distinct practice from resource recovery which focuses on delaying the rate of
consumption of natural resources
...

Waste management practices differ from developed and developing nations, for urban and
rural areas and for residential and industrial producers
...

Types of Solid Waste
Solid waste can be classified into different types depending on their source
...
This garbage is generated from residential and commercial complexes
...
For example, the solid waste in
Nairobi are a by-product of a broad spectrum of industrial, service and manufacturing
processes
...
The secondary
smaller generators include electroplaters, construction firms, dry cleaners and pesticide
applicators
...

Hazardous Waste/Industrial Waste
There is still no internationally accepted definition of hazardous waste
...
Though the hazardous waste
account for only a small proportion of all the waste generated by industries, their impact can be
disastrous as they not only affect the physical environment, but also the biotic components
...
g
...
Household wastes
that can be categorized as hazardous waste include old batteries, shoe polish, paint tins, old
medicines and medicine bottles
...
With increase in the global population, and
the rising demand for food and other essentials, there has been a rise in the amount of waste
being generated daily by each household
...
However, either due to resource crunch or inefficient infrastructure, not all
of this waste gets collected and transported to the final dump sites
...
Waste that is not properly managed, especially
excreta and other liquid and solid waste from households and the community, are a serious
health hazard and lead to the spread of infectious diseases
...
The wet waste decomposes and releases a bad odour
...
Plastic waste is another cause for ill health
...
Direct handling of solid waste can result in
various types of infectious and chronic diseases, with the waste workers and the trash pickers
being the most vulnerable
...
Exposure can lead to diseases through chemical
exposure as the release of chemical waste into the environment leads to chemical poisoning
...
Other high risk groups
includes populations living close to a waste dump and those whose water supply has become
contaminated either due to waste dumping or leakage from landfill sites
...
Other than this, core disposal of
industrial hazardous waste together with municipal waste can expose people to chemical and
radioactive hazards
...
Waste dumped near a water source also causes contamination of the water body or
the ground water source
...
Disposal of hospital and other medical waste requires special
attention, since this can create major health hazards
...

Waste treatment and disposal sites can also create health hazards for the neighborhood
...
Recycling also
carries health risks if proper precautions are not taken
...
Disposal of healthcare waste requires special
attention since it can create major health hazards such as Hepatitis b and c, through wounds
caused by discarded syringes
...


Occupational Hazards Associated with Waste Handling
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Skin and blood infections resulting from direct contact with waste and from infected
wounds
Eye and respiratory infections resulting from exposure to infected dust especially during
landfill operations
...

Intestinal infections that are transmitted by flies feeding on the waste
...

Bone and muscle disorders resulting from the handling of heavy containers
Poisoning and chemical burns resulting from contact with small amount of chemical
waste mixed with general waste
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HAZARDOUS WASTE
The US EPA (Environment Protection Agency) defines wastes as being hazardous if it may cause
or significantly contribute to an increase in mortality or serious irreversible or incapacitating,
reversible illness; pause a substantial hazard to human health or the environment when
improperly treated, stored, transported, disposed of or otherwise managed; and the
characteristics can be measured by a standardized test or reasonably detected by generators of
solid waste
...
The distinction must also be made between as hazardous
substance and hazardous waste
...
Hazardous waste is a material that has been used, spilled or is no longer needed
...

 The material exhibits ignitable, corrosive, reactive or toxic characteristics
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Generation of Hazardous Waste
These wastes originate from a range of industrial, cultural, commercial and institutional
activities and from both manufacturing and non-manufacturing facilities and processes
...
After a waste is generated, the generator can either
manage the waste on site or transport it offsite (usually to a commercial hazardous waste
facility) for treatment, disposal or recycling
...
Hazardous waste regulations place the responsibility
for proper disposal on the generator of that waste
...
Examples include paint waste, certain degreasers or other solvents
...



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A non-liquid capable of spontaneous and contained combustion under normal
conditions
...

An oxidizer

Corrossivity this is the degree to which one can react easily with other waste, dissolve metals
and other materials or burn the skin of an individual
...
A waste that exhibits either of the
following properties is considered as hazardous waste:



An aqueous material with a pH of less than or equal to 2 or greater than or equal to
12
...

A liquid that corrodes a substance to steam at a rate greater than 0
...


Reactivity reactive waste are unstable or undergo a rapid or violent chemical reaction with
water or other materials
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A waste that exhibits any of the following properties is considered to be
hazardous:

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Normally unstable and reacts violently without detonating
Reacts violently with water i
...
causes a sudden flash of fire accompanied by spattering
Forms an explosive mixture with water i
...
causes an explosion that may damage the
container or harm anyone near it
...
5

LECTURE 3; 9TH OCT 2018
Toxicity toxic wastes are considered to be hazardous because of the presence of toxic
constituents in the waste at greater than the established regulatory levels
...
To determine if a waste displays
toxicity characteristics, a test method i
...
toxicity characteristic leaching procedure, is
performed
...

Other Characteristics medical waste that may be infectious include used bandages and
hypodermic needles, human tissues and blood, and biological substances generated by
hospitals and such institutions
...


SOLID WASTE MANAGEMENT
The problems associated with the management of solid waste in today’s society are complex
because of the magnitude and diverse nature of the wastes coupled with the development of
sprawling urban areas, the funding limitations for public services in many large cities, the
impact of technology and the emerging limitations in both energy and raw materials
...

Fundamental Elements of Solid Waste Management
The primary steps are generation, collection, sorting and separation, transfer and disposal
...
This location may be a material processing facility, a
transfer station or a landfill disposal site
...
Handling also encompasses the movement
of loaded containers to the point of collection
...

Processing and Transformation of Solid Waste
The types of means and facilities that are now used for the recovery of waste materials that are
being separated at the source include curbside collection, drop off and buy back centres
...

Transfer and Transport
This element involves two main steps
...
The waste is then transported, usually over long
distances, to a processing or disposal site
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A modern
sanitary landfill is an engineered facility used for disposing solid waste on land without creating
new senses or hazards to public health or safety such as the breeding of insects and the
contamination of ground water
...
Several technologies have been developed that
make the processing of Municipal Solid Waste (MSW) for energy generation cleaner and more
economical than ever before, including landfill gas capture, combustion, pyrolysis, gasification
and plasma arc gasification (changing solid waste into gas but using more modern equipment)
...


Waste Management Strategies
The actions to reduce the output of solid waste generally fall into 3 broad categories;
1) Output Approach
This is the traditional response to solid waste and consists of ways to deal with trash flowing
out of towns and cities
...

2) Input Approach
This is a more sustainable strategy and consists of activities that reduce the amount of
materials entering the production-consumption cycle
...

3) Throughput Approach
This consists of ways to direct materials back into the production-consumption system, creating
a closed loop (cyclic) system like those found in nature
...


Throughput Approaches

Compost

Recycle & recycle

Mining

Raw Materials

Finished
Product

Use

Discard

Input approaches;
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Increased product
durability
Decreased material
products

Output approaches;
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Sanitary landfill
Incineration

OUTPUT APPROACHES
LANDFILLS
This is a natural or human made depression into which solid waste are dumped, compressed
and covered daily by a layer of soil
...
Landfills may
include internal waste disposal sites (where a producer of the waste carries out his/her own
waste disposal at the place of production) as well as sites used by many producers
...

Landfills are highly regulated waste depositories run by a government body that must adhere to
waste treatment laws and processing regulations
...
The garbage in the landfill must be covered with soil on a daily basis
...
The process of creating and using a
landfill adheres to the following basic steps
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A leachate (liquid produced when water percolates through any permeable material)
collection system is placed at the bottom of the pit
...

There is a groundwater tester well placed beside the pit to monitor possible
contamination
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The pit is filled with waste collected from nearby municipalities
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The pit is repeatedly filled with garbage and covered with soil until it is full
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LECTURE 4; 16TH OCT 2018
Site Selection for Landfills
The ideal site for landfills should be:
 Hydraulically acceptable pausing no potential threat to water quality when used for
waste disposal
...
The location of a landfill, to minimize the distance, from the waste collection area is
important, particularly if the operator does not collect the waste
...

 Situated at a distance of more than 200 meters from any dwelling
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 Having good access from highway systems and not interfering with existing traffic
patterns
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 Having electrical, water and sewage facilities nearby
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 Having a sufficient store for materials suitable for covering each individual layer of
waste
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Note: in practice, most sites cannot meet all these criteria
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Landfill Operations
During landfill operations, the waste collection vehicles are weighed at a weigh-bridge on
arrival and their load is inspected for waste that do not accord with the landfill’s waste
acceptance criteria
...
The compactors or
bulldozers are used to spread and compact the waste on the working phase
...
If
necessary, they return to the weigh-bridge in order to be weighed without their load
...
Typically, in the working phase, the compacted waste is covered with soil daily
...
The space that is occupied daily by
the compacted waste and the covered material is called a daily cell
...
Factors such as waste compressibility, waste-clear thickness
and the number of purses of the compactor over the waste affect the waste densities
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The quantities of cover material are calculated at the design stage and
suitable sources located
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Lack of suitable plant and machinery unless careful planning is carried out, existing
plant and equipment may not be able to cope with the additional work loads
...

Plant breakdown the atmosphere on landfills is laden with airborne particles which
settle on the site and regularly get drown into air intakes and cooling vanes and
radiators
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It is therefore important that plant and equipment is maintained regularly
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Weather conditions  severe weather conditions in form of frost and snow can
sometimes make the remote parts of landfills inaccessible
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This results in collection vehicles
becoming bogged down
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This becomes airborne when vehicles travel across
it
...
In some cases,
municipal vehicles collect hot ashes which ignite the waste in the vehicle
...
If the vehicle is delayed for some reason in
travelling to the landfill, the contents can ignite
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Fires are also caused by people burning copper and
plastic waste to melt plastic sheathing to leave copper which is then sold for scrap
...
Rodents also spread
many dangerous diseases e
...
rabies
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Differences between Landfills and Dumps
Both landfills and municipal dumps are geographical areas set aside for the collection and
deposition of consumer waste
...
Dumps are considered illegal because they do not adhere to regulations regarding
the burying of waste and controlling of groundwater contamination
...
What makes a
dump different from a landfill is the absence of the following requirements;
 Government regulated practices of operation such as how to control waste, prevent
odour and deter pest
...
e
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 Restrictions on location  a dump is anywhere that residents or municipalities have
found space to deposit garbage
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 Capture of leachate waste that comes off solid waste and can contaminate drinking
water
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OCEAN DUMPING
This is the dumping or placing or materials in designated places in the ocean, often on the
continental shelf
...
In some cases, ocean
dumping is regulated and controlled, while some dumping occurs haphazardly by ships and
tankers at sea, or legally within coastal waters
...

Bilge water can contain a number of toxic chemicals as well as biological agents that can affect
marine ecosystems and marine organisms, some of which are subsequently consumed by
humans
...
Periodically, medical and other wastes from legal and illegal dumping have
washed up on beaches, resulting in the exposure to beach goers, and in some cases the
closure of beaches until the wastes are removed
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From a public health perspective, expectant

women and young children are most at risk from the consumption of contaminated fish
and shellfish
...
The motivation for banning ocean
dumping gained momentum when contaminated wastes sewage-derived microorganisms were
discovered in public beaches, shellfish beds were contaminated with toxic metals and fish were
infected by lesion-causing parasites
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LECTURE 5; 23RD OCT 2018
INCINERATION
This is a waste treatment process that involves the combustion of organic substances contained
in waste materials
...
Incineration of waste materials converts the waste into ash,
flue gas and heat
...
The flue gases must be
cleaned of gaseous and particulate and pollutants before they are dispersed into the
atmosphere
...
Incineration with energy recovery is one of the several Waste-to-Energy (WtE)
technologies such as gasification, plasma arc gasification, pyrolysis and anaerobic digestion
...

Incinerators reduce the original solid mass of waste by 80-85% and the volume by 95%
depending on composition and degree of recovery of materials such as metals from the ash for
recycling
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Garbage trucks often reduce the volume of waste
using an inbuilt compressor before delivery to the incinerator
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Incineration has particularly strong benefits for the treatment of
certain waste types in the niche areas such as clinical waste and certain hazardous waste where
pathogens and toxins can be destroyed by high temperatures
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Types of Incinerators
An incinerator is a furnace for burning waste
...
There are various types of incinerators such as;
Burn Pile/Pit
This is one of the simplest and earliest forms of waste disposal, essentially consisting of a
mound of combustible materials piled on bare ground and set on fire
...
Burn piles can spread uncontrolled fires, for example, if wind blows
burning material off the pile into surrounding combustible gases of onto buildings
...
Even in a situation of no wind, small light-weight ignited embers can lift off the pile via
convection, and waft to the air into grasses or onto buildings igniting them
...
The barrel prevents the spread of
burning material in windy conditions, and as the combustibles are reduced, they can only settle
down into the barrel
...

Overtime, the very high heat of incineration causes the metal to oxidize and rust, and
eventually the barrel itself is consumed by the heat and must be replaced
...
The temperatures in a burn barrel
are not regulated and usually do not reach high enough or for enough time to completely
breakdown chemicals such as dioxins in plastics and other waste chemicals
...

Moving Grate
This is commonly used in municipal solid waste management
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A single moving grate boiler can handle up to 35 metric tonnes of
waste per hour and can operate 8,000 hours per year with only one scheduled stop for
inspection and maintenance of about one month’s duration
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The waste is introduced by a
waste crane through the throat at one end of the grate from where it moves down over the
descending grate to the ash pit in the other end
...

Part of the combustion air (primary combustion air) is supplied through the grate from below
...
Cooling is important for the

mechanical strength of the grate, and many moving grates are also water-cooled internally
...
It facilitates complete combustion of the flue gases by introducing turbulence for better
mixing and by ensuring a surplus of oxygen
...

Rotary Kiln
This is used by municipalities and by large industrial plants
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e
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The primary chamber consists of an inclined refractory lined
cylindrical tube
...
In the
primary chamber, there is conversion of the solid fraction to gases through volatilization,
destructive distillation and partial combustion reactions
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Fluedized Bed
A strong air flow is forced through a sand bed
...
The sand with pretreated waste and/or fuel is kept suspended on pumped air currents and takes on a flued-like
character
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This allows all of the mass of waste, fuel and sand to be fully
circulated through the furnace
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Before the flue gas cleaning system, the flue gases may contain significant amounts of
particulate matter, heavy metals, dioxins, furans, sulfur dioxide and hydrochloric acid
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Dioxins and furans are
considered by many to be serious health hazards
...
While plastic does usually burn in an open air fire,
the dioxins remain after combustion and either float off into the atmosphere or may remain in
the ash where it can be leached down into ground water when it rains on the ash pile
...
It means separating, collecting, processing, marketing and
ultimately using a material that would otherwise have been thrown away
...
Quality
products and packaging are been made from recycled materials that have been recovered from
the waste stream
...

Reuse is the return of operable or reparable goods into the market system for someone to use,
for example; shoes, silver-wear etc
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Most of
the garbage generated in a household can be recycled and reused
...

Benefits of Recycling
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It reduces air, land and water pollution/emissions associated with landfilling and
incineration
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It saves on energy resources needed to manufacture new products
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It helps sustain the environment for future generations
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This waste can be
recycled by the method of composting, one of the oldest forms of disposal
...
Composting is a biological process in which microorganisms, mainly fungi and
bacteria, decompose organic matter into humus-like substance
...
The
process of composting ensures the waste that is produced in the kitchen is not carelessly
thrown and left to rot
...
Apart from being
clean, cheap and safe, composting can significantly reduce the amount of disposable garbage
...
It increases the soil’s ability to hold water and makes the soil easier to
cultivate
...

o It supplies part of the 16 essential elements needed by the plants
...

o It makes the soil easier to cultivate
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o It aids in preventing soil erosion by keeping the soil covered with greenery
...


INPUT APPROACHES
This involves practices such as increasing the product’s lifespan by making more durable
products, reducing the amount of materials in products and packaging, and reducing
consumption
...
An example of sources
reduction is bringing a reusable bag to the grocery store
...


Buy reusable or refillable products
...
Avoid
single serving sizes
...

Buy durable bags
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Improve product design to use fewer materials
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 Work with customers to design and
implement a packaging return program
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 Purchase products in bulk
...
It ranges from legislation and agreements at the national level for packaging and
product design to local programs to prevent recyclables and compostable organics from
entering the final waste streams
...

Source Separationkeeping different categories of recyclables and organics separate at the
source i
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at the point of generation to facilitate the reuse, recycling and composting
...

Redemption Centrewaste trading centre enterprise that buys recycling materials and sells to
brokers
...

Producer Responsibilityproducers accept the degree of responsibility for the waste that
result from the goods and/or services that they market, by reducing materials used in
production, making repairable or recyclable goods and/or reducing packaging
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Instead of buying new
containers from the market, use the ones that are in the house
...

RecycleSegregate your waste so that non-perishable waste are collected and taken for
recycling
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g
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Promoting Waste Reduction at the National & Local Level
The action for waste reduction can take place at both national and local levels
...

Promotion of consumer awareness
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At the local level, the main means of reducing waste are:
Diversion of materials from the waste stream through source separation and trading
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Pressure on the national or regional governments for legislation on redesigning
packaging or products and support of composting either centralized or small scale
...
Remediation is generally subject to an array of
regulatory requirements and also can be based on assessments of human health and ecological
risks, where no legislated standards exists or where standards are advisory
...

REMEDIATION STRATEGIES
There are a number of different methods employed dealing with soil contamination
...
It is not unusual for a
given tract of land to undergo more than one cleanup operation in order to deal with the
presence of multiple contaminants
...

Ex-situ methods involve the excavation of affected soils and subsequent treatments at the
surface, while in-situ methods seek to treat the contamination without removing the soils
...
This
process involves extracting soil that is contaminated and transporting it to a landfill set aside for
this purpose
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If the
contamination affects a river or a bay bottom, then dredging of bay mud or other silty place
containing contaminants may be conducted
...
In geologic
formations that allow delivery of hydrocarbon mitigation agents or special surfactants, this
approach provides a cost effective and permanent solution to sites that have been previously
unsuccessful, utilizing other remedial measures
...

3) Pump and Treat
This involves pumping out of contaminated groundwater with the use of submersible or
vacuum pump and allowing the extracted groundwater to be purified by slowly proceeding
through a series of vessels that contain materials designed to adsorb (to accumulate on the
surface) the contaminants from the groundwater
...
Chemical reagents such as flocculants
followed by sand filters may also be used to decrease the contamination of groundwater
...
Depending on geology and soil type, pump and
treat may be a good method
...
It is more
difficult to reach sufficiently low concentrations to satisfy remediation standards due to the
equilibrium of absorption (chemistry)/desorption processes in the soil
...

4) Solidification and Stabilization (S/S)
This technology relies on the reaction between a binder and soil to stop/prevent or reduce the
mobility of contaminants
...
g
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Solidification involves
addition of reagents to the contaminated material to impart physical/dimensional stability to
contain contaminants in a solid product and reduce access by external agents (e
...
air and
rainfall)
...
However, the
uptake of S/S technologies have been relatively low and a number of variants have been
identified, including;
 The relatively low cost and widespread use of disposal to landfills
...

 Uncertainty over the durability and rate of contaminant release from S/S treated
material
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 Residual liability associated with immobilized contaminants remaining on-site, rather
than their removal or destruction
...
Oxygen gas or ambient air can also be injected to promote
growth of aerobic bacteria which accelerate natural attenuation of organic contaminants
...
In general, though, aerobic activity is much faster than anaerobic and overall
destruction rates are typically greater when aerobic activity can be successfully promoted
...
In these cases, injections down gradient of
groundwater flow may provide adequate microbio-destruction of contaminants prior to
exposure to surface waters or drinking water supply wells
...
Certain
metals are more so removed in oxidizing environments while others are more mobile in
reducing environments
...
Bioremediation is sometimes used in conjunction with a pump-and-treat
system
...
This is sometimes referred to as bio-gac
system
...
Occasionally, the bacteria can build up to such a point
that they can affect filtration and pumping
...
Myco-remediation is a form of bioremediation where fungi is used to return an
environment contaminated by pollutants to a less contaminated state
...


EMISSION STANDARDS
Standards are set for the levels of dust, noise, odour, emissions to air and groundwater and
discharge to sewers or waterways of all chemicals of concern or chemicals likely to be
produced, during the remediation by processing of the contaminants
...
Monitoring for
compliance against each standard is critical to ensure that exceedances are detected and
reported both to authorities and the local community
...

Penalties are significant as otherwise fines are treated as normal expense during business
...


LECTURE 8; 20TH NOV 2018
STATUS OF MUNICIPAL SOLID WASTE MANAGEMENT (MSWM) IN KENYA
Most local authorities spend over 30% of their budget on refuse collection but collect only up to
50-70% MSW
...
They do not use sanitary landfills and the trucks that are used have a low collection
efficiency
...
The people of Kenya
have also done their part by employing the four R’s in solid waste management
...
8 of 1999)


Solid waste segregation and reduction at production and consumption of levels
...




Treatment of waste and Landfills
This emphasizes the need to treat the waste before it is disposed of
...
This ensures that the
incinerators are always inspected and audited
...




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