SWM - Lecture.pptx

Contents
Solid waste management
Definitions
Public health importance
Environmental and Health Impact of Solid Waste
Functional elements of solid waste
Integrated waste management and waste management hierarchy

SOLID WASTE MANAGEMENT
- Definition of terms
• Waste: Any substance or object which the holder
discards or intends to discard; or it is used to describe
materials that are perceived to be of negative value.
• A holder means the producer of the waste or the
person who is in possession of it.
• Producer means any person whose activities produce
waste

Definitions
• Solid wastes: are all the wastes arising from human and animal
activities that are normally solid and that are
discarded/useless/unwanted.
• Waste management: is associated with the control of generation,
storage, collection, transfer and transport, processing and disposal of
wastes in a manner that is in accordance with the best principles of
public health, economics, engineering, conservation.

Definitions
• Bioaccumulation: is an increase in concentration of a pollutant from the
environment to the first organism in a food chain.
• Biomagnifications: is an increase in concentration of a pollutant from one
link to another in a food chain
 Solid waste management:
– A systematic administration of activities that provide for the collection,
source separation, storage, transportation, transfer, processing, treatment
and disposal of solid waste.

Public health importance of Solid Waste
1. Can be best media for the growth of microorganisms.
2. Attraction of arthropods such as housefly.
3. Attraction of rodents/other animals, rats, dogs
4. Contaminate water sources
5. Contaminate food supply
6. Can create fire accident
7. Can create nuisance :-
 Bad odor, smoke, dust
 Aesthetical problem & discomfort: sneezing, coughing
8. Affects socio-economic conditions
9. Affects climate and creates air pollution

Risks and Problems Associated with Solid wastes
If solid wastes are not managed properly, ther e are many negative impacts
that may result:
- Infectious disease risks from poorly managed solid waste
- Contamination of drinking water and soil by biological, chemical, and
mining wastes
- Gas migration and leachate discharges from landfills
- Emissions of air pollutants from incinerators
- Contamination of food by waste chemicals that escape into the
environment

Functional elements of solid waste
• It includes the activities involved with the management of solid
wastes from the point of generation to final disposal:
1. Waste generation
2. Onsite handling, storage and
processing
3. Collection
4. Transfer and transport
5. Resource recovery and processing
6. Disposal.

Functional elements of solid waste management system:
• There are six elements of a waste management system.
1. Waste generation:
• Includes activities in which materials are identified as no longer
value and are either thrown away or gathered together for disposal.
2. Waste handling, separation, Storage and processing at the
source:
- Those activities associated with the handling, storage, and
processing of solid wastes at or near the point of generation
8

2… handling, storage and processing…
• Onsite means these functions are concerned with solid waste at the
place where the waste is generated.
• Handling means the separation of wastes into their different types so
they can be dealt with in the most appropriate way, for example,
separating putrescible waste for composting.
• The benefits of appropriate onsite handling include reducing the
volume of waste for final disposal and recovering usable materials.

3. Collection:
• It involves not only the gathering of wastes and recyclable materials, but
also the transport of these materials, after collection, to the location
where the collection vehicles emptied.
 This location may be material processing facility, a transfer station or a
landfill disposal site.
10

4. Transfer and transport:
 It involves two steps:
• The transfer of wastes from the smaller collection vehicle to the larger
transport equipment.
• The subsequent transport of the wastes, usually over long distances, to a
processing or disposal site.
• Although motor vehicle transport is most common, rail cars and barges (flat
bottom large boats) are also used to transport wastes.
15

4. Processing and recovery of waste:
• Those techniques equipment and facilities used both to:
- improve the efficiency of the other functional elements and
- recover usable materials, conversion products, or energy from solid
wastes.
16

6. Disposal:
• The final functional element in the waste management System is disposal.
• In many parts of the world, even today, land-filling or land spreading is the
ultimate fate of all solid wastes.
 Methods of solid waste treatment and disposal system:
1. Ordinary open dumping
2. Controlled tipping/burial
3. Hog feeding
4. Incineration
5. Sanitary landfill
6. Compositing
7. Grinding and discharge into sewers
20

Methods of solid waste treatment and disposal system:
6.1. Open Dumping
• Some components of solid waste such as street sweepings, ashes and non combustible
rubbish are suitable for open dumping.
• Garbage and any other mixed solid wastes are not fit or suitable because of nuisance and
health hazard creation.
6.2. Controlled tipping/burial
• Indiscriminate dumping of garbage and rubbish creates favorable conditions for fly-
breeding, shelter and food for rodents, nuisances etc.
• In order to avoid such problems, garbage and rubbish should be disposed of under
sanitary conditions.
• This can be done by digging shallow trenches, laying down the waste manually or
mechanically and covering by ash at the end of each days work.
6.3. Hog Feeding
• The feeding of garbage to hogs has been practiced for many years in different parts of the
world. 21

Methods of solid waste treatment and disposal system
6.4. Incineration
• Incineration is a process of burning the combustible components of
garbage and refuse.
• Can be effectively carried out on a small scale in food service
establishments as well as in institutions such as hospitals, schools etc.
6.5. Sanitary Landfill:
• Is an engineered facility used for disposing of solid wastes on land or
within the earth’s mantle-
• without creating nuisances or hazards to public health or safety, such as
breeding of rats , insects and the contamination of groundwater.
• It is one of the most widely used means of solid waste disposal system .
22

• The natural anaerobic decomposition of the waste in the landfill
produces landfill gases which include Carbon Dioxide, methane and
traces of other gases.
• Methane can be used as an energy source to produce heat or electricity.
• Thus some landfills are fitted with landfill gas collection (LFG) systems to
capitalize on the methane being produced.
23

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Main features of a modern landfill
• The typical design of a landfill is as
follows:
• the bottom is lined with a dense
layer of clay and sealed with
thick plastic sheeting to contain
leaks of hazardous materials.
• A flexible membrane liner is
designed to hold in toxic
chemicals

6.6. Composting
• Composting is an effective method of solid waste disposal.
• Biodegradable materials break down through natural processes and
produce humus.
• The metabolism of micro-organisms breaks down the waste aerobically
or an aerobically.
• Aerobic respiration, typical of composting, results in the formation of
Carbon dioxide and water.
• While the anaerobic respiration results in the formation of Carbon
Dioxide and methane.
25

• In addition to generating the humus which is used as a soil enhancer,
Anaerobic Digestion is also used as a method of producing biogas which
can be used to generate electricity.
7. Grinding and Discharge into Sewer Lines:
• The location of central grinding stations at convenient points along the
sewer system or at the sewage treatment plant is required.
26

Integrated waste management and waste management
hierarchy
27
Most Preferable
Least Preferable

…waste management hierarchy
1) Avoid : avoid wastes from the production .
2) Reduce: Source reduction
 Minimize the amount of waste being generated
 Make products last longer
• The term source reduction refers to “reducing waste at the source,
and is the most environmentally preferred strategy.”
• Through source reduction, the volume of solid waste that must be
deposited in landfills is limited.
• Two important components of source reduction are waste
reduction and waste recycling.
• Waste reduction aims to reduce the amount of waste produced at
the source.
• Waste recycling refers to reuse of materials in the waste.
28

3) Reuse
 Repeated use of items prior to disposal
 Repair the item like plastic
4) Recycling
1. Resource conservation
 Recycling reduces pressure on renewable & non-renewable resources
2. Energy conservation
 Recycling consumes 50–90% less energy than manufacturing the same
item from the previous material
3. Pollution abatement
Reduces level of pollutant emissions
29

4) Recycling
• Recycling is the process of collecting and reprocessing a resource so it
can be used again. Example: collecting aluminum cans, melting them
down, and using the aluminum to make new cans or other aluminum
products.”
• The advantages of recycling include the following:
- Reduces emissions of greenhouse gases.
- Prevents pollution generated by the use of new materials.
- Preserves natural resources and energy saving
5) Recover and treatment
using solid materials as source of energy
30

Treatment technologies
5.1. Composting
• Composting breaks down organic materials through the action
of physical and chemical processes.
• Composting consists of the biological breakdown of solid organic matter
to produce a humic substance (compost) which is valuable as a fertilizer
and soil conditioner.
• Night soil or sludge may be composted with straw and other vegetable
waste, or with mixed refuse from domestic, commercial or institutional
premises. The process may be aerobic or anaerobic.
• Aerobic bacteria combine some of the carbon in organic matter with
oxygen in the air to produce carbon dioxide, releasing energy.
31

• The rest is converted to heat, often raising the temperature to more than 70°C.
At high temperatures there is rapid destruction of pathogenic bacteria and
protozoa, worm eggs and weed seeds.
• All faecal microorganisms, including enteric viruses and roundworm eggs, fly
eggs, larvae and pupae will die if the temperature exceeds 46 °C for one
week. No objectionable odour is given off if the material remains aerobic.
• In the absence of oxygen:
• Nitrogen in organic matter is converted to acids and then to ammonia;
• Carbon is reduced to methane and
• Sulfur to hydrogen sulfide.
• There is severe odour nuisance. Complete elimination of pathogens is slow,
taking up to twelve months for roundworm eggs.
32

Thermophilic/Mesophilic Digestion
 The digestion temperature:
(i) 35°C for mesophilic digestion or
(ii) 53–55°C for thermophilic digestion.
 Selection of process temperature is a
balance between several factors.
34

5.2. Landfills
• Materials that cannot be recycled or composted need to be deposited in
landfills.
• Leachate:
• It refers to “water that collects contaminants as it trickles through wastes.
• Leaching may occur in farming areas, feedlots, and landfills, and may result
in hazardous substances entering surface water, ground water, or soil.”
• Leachate is a liquid that has percolated through solid waste or another
medium and has extracted, dissolved, or suspended materials from it, which
may include potentially harmful materials.
• Leachate collection and treatment is of primary concern at municipal waste
landfills.
39

Landfill processes and technologies
A municipal solid waste landfill site

Incineration
• Reduces waste volume by 80–90% by incineration for solid wastes
• but odor and smoke are negative effects.
45

46
• Incineration has been used for all types of wastes, including municipal
solid wastes, sewage sludge, industrial and hazardous waste, and
medical wastes.

Characteristics of Hazardous Waste:
1. Flammability and Ignitability : The waste burns or
explodes with the application of fire, friction, electricity
spark, or any source of heat.
• wastes with high ignitable potential and/or which burn
vigorously and persistently.
2. Corrosively: It is the ability of the waste to cause skin and
mucosal membrane damages, burns and erosions.
3. Reactivity: A waste that reacts violently with water with
the formation of toxic fumes and gases.
48

4. Toxicity: A waste that is likely to produce mass acute
and chronic poisoning; long-term health effects.
5. Infectivity: A waste is a potential cause for infectious
diseases, such as hepatitis B.
6. Radioactivity: Wastes containing radioactive elements.
• Such wastes are mainly from biomedical training and
research institutes.
7. Bioaccumulation effect: Wastes that are not easily
degraded when exposed with the environment.
49

 Treatment technologies:
• The most common methods of treating hazardous waste
are divided into Physical, Chemical, and Biological.
• Physical treatment processes include gravity separation,
phase change systems such as air and stream stripping of
volatiles from liquid wastes and-
• various filtering operation including carbon adsorption.
• Ex. (drying, screening, grinding, evaporation,
sedimentation, filtration, fixation) etc.
50

• Biological methods: Use of enzymes (natural or genetically
engineered microorganisms)to eliminate hazardous substances
(found in sewage, waste stream sand sludge's and soils)or to
convert them into less hazardous or useful forms.
• (composting, aerobic and anaerobic decomposition, activated
sludge, enzyme treatment)etc.
• Chemical methods: Oxidation, reduction, neutralization,
hydrolysis, etc.
• Thermal methods: incineration, boiling, autoclaving, UV
treatment, microwave use, etc.
51

 Disposal methods of hazardous wastes:
1. Secure landfills
2. Incineration
3. Recycling
4. Deep well injection
5. Biological methods
52

Infectious waste:
 Infectious waste is a waste which is suspected to contain pathogens (
bacteria, virus, parasites or fungus) in sufficient condition to cause disease on
susceptible host.
• Infectious waste includes human blood and blood products, cultures, stocks of
infectious agents.
• pathological wastes, contaminated sharps (hypodermic needles, scalpel blades,
capillary tubes), contaminated laboratory wastes.
• contaminated wastes from patient care, discarded biological, contaminated
animal carcasses and body parts infected with human pathogens.
53

 Health hazards:
• Health-care workers (particularly nurses) are at greatest
risk of virus infections such as HIV/AIDS and hepatitis
B and C, through injuries from contaminated sharps
(largely hypodermic needles).
• Other hospital workers and waste-management operators
outside health-care establishments are also at significant
risk, as are individuals who scavenge at waste disposal
sites (although these risks are not well documented).
54

Health care waste
• Health care waste: is the total waste generated by hospitals, healthcare
establishments & research facilities in the diagnosis, treatment, or
immunization of human beings or animals, & other associated research &
services (WHO).
Healthcare waste categories:
a. Low risk waste- communal wastes.
• Approximately 85% of the general waste produced by hospitals &
clinics is non-contaminated waste & poses no infection risk to persons
who handle it.
b. High Risk Wastes
55

Health care waste
Health effects of Healthcare Wastes
 Needle stick injuries
 Transmission of infection example from re-use of some type of
waste -e.g., syringe
 Environmental pollution e.g., air, water
 Exposure to radiation
 Fires
 Public nuisance (offensive smells, unsightly)
56

Health Care Waste Management
 HCWM is defined as actions associated with the control
of generation, storage, collection, transport & disposal
of HCWs in accordance with the best principles of
public health.
 Importance of proper HCWM
 Minimizes the spread of infection
 Minimizes accidental injury
 Reduces environmental pollution
 Reduces odors & aesthetic problems
57

Category of HCWs Health effects
Infectious waste Respiratory infections, genital infections, skin infections,
meningitis, AIDS, Viral Hepatitis A, B and C
Radioactive waste Cancer, burn & skin irritation, headache, dizziness, etc
Sharps Double risk: injury & potential transmission routes for
HIV & Hepatitis B & C from contaminated sharps
Pharmaceutical
Waste
Ineffective medical care from consumption of expired
pharmaceuticals, pollution of env’t
Hazardous chemical
waste
Intoxication, burns & skin irritation, pollution of env’t ,
possibility of fire, poisoning
Pressurized
containers
Injury from explosion
Genotoxic waste Carcinogenic and mutagenic, skin/eyes irritation, nausea,
headache, or dermatitis 58

 Key steps in HCW management
a. Waste Minimization
b. Segregation/ separation
c. Handling
d. Transporting
e. Treatment
f. Disposal
59

a. Waste Minimization
 Waste minimization is the first & best way to:
 Reduce HCW quantities & costs
 Reduce env’tal impact on air pollution & landfill
capacity
 All purchases of material & supplies should be made
with waste reduction in mind
 Improving reuse & recycling practice
 Administrative controls
60

b. Waste Segregation/ Separation
 Is separating waste by type at the place where it is
generated.
 Waste should be separated immediately by the person
generating the waste.
 Waste handlers should never sort through waste after it
has been placed in the bin.
 Segregation must be maintained throughout until final
disposal
 Segregation will result in a clear solid waste stream. 61

c. Handling, i.e. collecting, storing…
 Protective clothing should be worn by waste handlers.
 Aprons, Heavy duty gloves, Footwear, Goggles/glasses and masks, Hands should
be washed.
• Waste collection : Collect, quantifying by volume, labeling as to its source &
recording.
• Storage: Placing waste in a secure place until it can be disposed
 Ideal storage area should be:-
 Designed, secure, kept clean, dry and pest free
 HCW should be stored no longer than one week
 Organic waste should be disposed daily
63

d. Transport: Transport of the wastes from the source to
the disposal or treatment area.
e. Treatment
 Methods used to render the waste non-hazardous
 Steam sterilization
 Incineration
 Thermal deactivation
 Gas/vapor sterilization
 Chemical disinfection
64

65
Types of Waste Recommended
treatment
Recommended procedures
Microbiological
waste
Autoclave As per instruction with the
machine
Pathological
waste
Liming Dig pit, place lime, add
waste, more lime, add soil
Infectious fluid Chemical 1% hypochlorite solution
Let sit for 10-15 min.

F. Disposal of Health Care Waste:
 Eliminating or transporting healthcare waste from
the facility
 Common disposal methods:
a. Bury
b. Incineration
I. Burial
– Advantage: Simple and inexpensive
– Concern:-
• Can handle small volume
• Presents a danger to community if not properly
buried
66

II. Incineration:
 Advantage:- Disinfects & greatly reduce waste
volume.
 Factors that influence effectiveness:
 Waste moisture content
 Combustion chamber filling
 Temperature/residence time
 Maintenance/repair.
 Concern:
 May produce emissions & hazardous ash
containing dioxins, metals & furans.
 May require pollution control equipment to
meet local env’tal regulations.
67

 Things that must not be incinerated:
PVC plastics( blood bags, IV lines etc)
• N.B Syringe bodies are NOT PVC plastic
 Mercury thermometers
 Batteries
 X-ray or photographic materials
 Aerosol cans or gas containers
 Glass vials
68

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