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Disposal of waste
1. By
Md Tanwir Alam, MD
Govt. Tibbi College & Hospital
1tanveernium@gmail.com
2. Disposal of Wastes
DOW is now largely the domain of sanitarians and public
health engineers
Health professionals have basic knowledge
Improper disposal + health hazards
Advice in special situation: camp sanitation, natural disasters
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3. Solid wastes
Garbage: food wastes
Rubbish: paper, clothing, plastics, wood, metal, throw away containers, glasses.
Demolition products: bricks, masonry, pipes
Sewage treatment residue: sludge & solid from domestic sewage.
Dead animals
Manure &
Other discarded materials
Should not contains Nightsoil
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4. Daily out put depends on
❑Dietary habit
❑Life style
❑Living standard
❑Degree of urbanisation &
❑Degree of industrialization
Daily solid waste production;
0.25 – 2.5 kg per capita
4
Out put of waste
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5. Nuisance - odours & Sight
Water & soil pollution
Decomposes & favours fly breeding
Attracts rodents & vermin
Pathogens conveyed from solid waste to man’s
food through flies & dust
Improper disposal = Vector borne disease
5
Health Hazards
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6. Street refuse: Leaves, straw, animal droppings, litters
Market refuse: Putrid vegetables & animal matter
Stable litter: Animal dropping, left over animal feeds
Industrial refuse: Inert-CaCO3, Highly Toxic/Explosive
Domestic refuse: Ash, Rubbish, Garbage
Garbage:
✓ Arising while preparation, cooking & composition of food
✓ It needs quick removal & disposal coz it ferments on storage
6
Source / types of solid waste
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8. Storage
Galvanized steel bin with close fitting cover
Capacities varies with no. of users & frequency of
collection
Out put: (estimated refuse out put in India/day/Capita)
1/10-1/20 c.ft./capita/day – family-5 person (bin- 5/10 -1/2 c.ft)
If collection done every 3rd days – bin 1 ½ - 2 c.ft
Paper Sack: western countries, thrown away with refuse
Public Bin: cover/without cover, concrete platform(2-3”) devoid flood water.
Mechanical handling: Metropolitan cities/capitals, lorries fitted with cranes
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9. Collection & Transportation
Depends upon funds available
House to house- best method but very few
Public bin; nearest, avoided usually
Transported through vehicle to ultimate disposal
Environmental Hygiene Committee (1949)
Recommend house to house collection/Public Bin
Open refuse cart replaced by enclosed vans
Dustless Refuse Collector
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10. Methods adopted as per local factors (Cost and
availability of land & labour)
Dumping
Burning
Controlled tipping or sanitary land fill:
Trench method , Ramp method, area method
Incineration
Composting: Bangalore, Mechanical, Vermicomposting
Manure pits
Burial
10
Methods of disposal
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12. Open & Low lying areas: reclamation of land & Easy method for dry refuse
Waste undergoes natural decomposition (by bacterial
action) – Humus
“a most insanitary method that creates public health
hazards” ; WHO Expert Committee (1967)
Health Hazards
▪ Breeding of flies & rodents = disease transmission
▪ Nuisance – smell & unsightly appearance
▪ Loose refuse dispersed by wind
▪ Drains get blocked
▪ Water contamination during rainy season
▪ Air pollution
12
Dumping
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13. Burning
For urban waste & hospital wastes (incineration)
Method of choice- where suitable land unavailable
Involves prior segregation of solid waste from dust
Plastic carry bags cant be subjected to burn
Not suitable for immediate disposal of organic waste
Use in disposal of small quantities of wastes, papers
etc. only
Has limited application in refuse disposal in India
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14. ▪ Done in open, low lying areas
▪ Most satisfactory where suitable land is available
▪ Modified
▪ Trench method:
▪ Long trench 2-3(6-10ft)deep X 4-12 (12-36 ft) wide meters dug out-
depending on local condition
▪ Refuse filled into this trench daily
▪ Refuse is compacted & covered with excavated earth-filled upto 2m
▪ For 10,000 people- required One acre land/year
▪ Advantages :
▪ Modification/hieghtening of law lying areas
▪ Biogas and compost production
14
Controlled tipping or sanitary land fill
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15. Ramp method
Sanitary land fill method for sloping areas
Excavation achieved for covering matterial
Area method
Sanitary land fill method
Done to filling land depressions, unused quarries & clay pits
Refuse is deposited, packed & consolidated in uniform layers up to 2-2.5m
(6-8 ft.) deep
Each layer is sealed (exposed surface) with thick mud cover (at least
30cm=12 inch)-sealing prevent infestation by flies & rodents and suppress
nuisance - smell & dust
Chemical, bacteriological and physical changes occurs in buried refuse
Within 7 days, temp raises above 60C- Kills all pathogens –hasten
the decomposition process – take 2-3 weeks to cool down
4-6 months to complete decomposition of organic matter to
innocuous mass
Disadvantage- requiring supplemental earth from outside
Modified sanitary land fill
Here refuse in trenches are covered with soil once or twice a week
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15
19. Composting
Method of combined disposal of refuse & Nightsoil
or sludge
Natural breakdown of organic under bacterial
action – Humus/Compost-manurial value for soil
By product- CO2, Water & Heat(>60˚C)
This heat destroy eggs & larvae of flies, weed
seeds and pathogenic agents in several days
End products/compost/soil builder- Nitrates &
phosphates (major Plant nutrients)
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20. Bangalore method
ICAR & IISc Bangalore – satisfactory method
Trench- 3ft. D X 5-8 ft B x 15-30ft L –A/C Need/amount
>3ft are not recommended- coz of slow decomposition process
Location- not less than 800m from city
Refuse layer- 15cm- spread on bottom of trench
Nightsoil – 5cm
Refuse & nightsoil alternately- till heap 30cm above ground level
The top layer should be of refuse at least 25cm
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21. Bangalore method Continued….
Then cover heap with excavated earth
7 days – compost mass/Bact.action/destroy pathogens/Parasites
4-6 months- manure/well decomposed/innocuous/odourless/high manurial value
The Environmental Hygiene Committee (1949)
Did not recommend composting by municipalities with a population over
100,000
Bigger municipalities should install underground transport human
excreta
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25. Mechanical composting
Compost manufactured on large scale
Refused is firstly cleared of salvageable
materials like rags, bone, metal glass & those
interfere with grinding operation
Pulverisation- size reduced to <2 inches
Then mixed with sewage, sludge or nightsoil in
a rotating machine & incubated
Factors kept in control- certain C-N ratio, temp.,
moisture, pH & aeration
Entire process took 4-6 weeks to complete
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26. Mechanical composting continued….
Abroad- Holland, Germany, Switzerland & Israel
India- Delhi, Nagpur, Mumbai, Chennai, Pune, Allahabad, Hyderabad,
Lucknow & Kanpur have offered to join for setting up pilot plants
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27. Manure pits
Rural India – thrown around houses – pollution & nuisance
Manure pits- digging for individual householders
Garbage, cattle dung, straw, leaves dumped &
covered with earth daily
Tow pits – used alternately when one is closed
5-6 months- manure; well for agriculture soil
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28. Burial
Suitable for small camps
Trench- 1.5m wide X2m deep
Covered with 20-30cm earth at the end of the day
When the level in the trench is 40cm from
ground level – filled with earth, compacted & new trench dug out
4-6 months - used as manure in agriculture soil
If trench is 1 meter in length- for every 200 persons filled
in about 1 week
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36. Public Education
Public health education by various means
➢ Pamphlets
➢ Newspapers
➢ Broadcasting
➢ Films
➢ Nukkad natak/play
➢ Celebrities appeal
➢ Social media
Strict low & order (police enforcement of low)
In syllabus – school
Training /workshop – working place/factories
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37. Economic & Finance
Disposal of wastes:
Efficient
Hygienic
Economic
Cost/Budget – depends on
• System/type/method adopted
• Culture –Political/social/religion
• Countries/state/cities economy
• Education
• Health awareness
Highly industrialized countries- 20% of budget on
collection & disposal of solid waste
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38. International cooperation
International Solid Wastes & Public Association
(ISWA) – 1970
To assist countries wanting to improve sanitary
services
WHO International Reference Centre (Switzerland) –
to collect, evaluate & disseminate information on
wastes- disposal practices and to foster research
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