9 Solid waste and liquid waste disposal.ppt

Solid waste

1. Solid and liquid
waste disposal

2. Why Doctors ?
Domain of sanitarians and public health
engineers.
Health professional need to have basic
knowledge.
Improper waste disposal cause health hazard
In special situation may be called upon to give
advice.
E.X –In natural disaster when there is
disruption of community health services.

3. Solid waste
Garbage –food waste
Rubbish –Paper, Plastics, Containers
Demolition products –Bricks
Dead animals
Discarded materials
Strictly it should not contain night soil
Exception -In Indiait is common to see night soil
in collection of solid waste.

4. Sources and Types
Street refuse
Market refuse
Stable Litter –Contains animal droppings and left
over animal feeds
Industrial refuse –Can range from inert materials to
highly toxic compounds
Domestic -Ash, Rubbish, Garbage.
Garbage contains organic material which decompose
on storage and needs quick removal.

5. Effects of Improper disposal
Improper disposal means wastes are
accumulated
Health Hazards :
1.Decomposes and favours fly breeding
2.Attracts rodents and vermin
3.Pathogens present in waste may be conveyed
back to mans food
4.Soil and water pollution
5.Is a Nuisance and cause bad odours.

6. Importance of Proper waste
disposal
Strong correlation between improper waste
disposal and incidence of vector borne diseases.
In all civilized countries there is efficient system
for its periodic collection, removal, and final
disposal without risk to health.

7. Disposal methods
First step in waste disposal is proper storage.
Steel Dust bin with close fitting cover should be used
for storage
Size of the bin depends on number of users and
frequency of collection.
Recent method is storing in paper sack and sack itself
is removed and replaced with new one
Public bins : Cater for larger population
Usually without cover
Placed on raised platform
Frequently emptied by municipality

8. Collection
House –House collection is the best
In India people are expected to dump in public bins
which is not followed and is dispersed all around.
Refuse collection vehicle transports the refuse to
place of disposal.
Usually done by open vehicle
Recommended inaddition to collection from public bins
also from individual houses and should transported in
enclosed vehicle.

9. Types of disposal methods
Different methods
No single method available which is
suitable for all circumstances
Method of disposal depends on cost and
availability of land and labour.

10. Principal methods
Dumping
Controlled tipping or sanitary land fill
Incineration
Compositing
Manure pits
Burial

11. Dumping
Dry refuse is disposed by this method
Easy method of disposal
Done in low lying area
As a result of bacterial action refuse decreases in
volume and converted into humus.
Drawbacks:
1.Exposed to flies and rodents
2.Source of nuisance –smell, appearance
3.Dispersed by wind
4.Lead to soil and water pollution
Insanitary methodof disposal

12. Controlled tipping
Most satisfactory method of waste
disposal
Suitable land should be available
Difference is waste is placed in a trench
and covered with earth.
Three methods are used :
1. Trench method
2. Ramp method
3. Area method

13. Trench method
Level ground available this method is
chosen.
Trench is dug 6 -10 ft depth and 12-36 ft
wide
Trench is then filled with refuse upto a
height of 6 ft and covered with excavated
earth

14. Ramp Method
Done in places where land is sloping
Refuse is disposed and covered with excavated
material
Area Method
Refuse is disposed in land depressions such as
disused quarries
Waste is filled in layers upto 6ft depth.
Each layer is covered with mud atleast 12
inches thick
Drawback : Needs supplemental earth from
outside source.

15. Mechanism of action
Chemical, bacteriological, and physical
changes occur in buried refuse.
Temperature increases to 60
.
C within 7 days
and kills pathogens and hastens decomposition
Takes 2 –3 weeks to cool down.
Normally it takes 4 -6 months for complete
decomposition of organic matter into innocuous
mass.
Sealing prevents infestation by flies and rodents
and suppresses nuisance from smell and dust.

16. Incineration
Disposed by burning or incineration
Hygienic method
No suitable land
Hospital waste is disposed by this method.

17. Composting
Natural process
Organic matter is decomposed by bacterial
action into relatively stable humus like material
called compost which has high manurial value.
Byproducts as result of this reaction is co
2
,
water, and heat.
Temperature of 60
.
C is attained during
decomposition which destroys egg, larvae, and
pathogens.
End product compost contain few or no disease
producing organisms

18. Methods of composting
1. Bangalore method ( Anaerobic )
2. Mechanical method ( Aerobic )
Bangalore method( Hot fermentation
process)
•Satisfactory method
•Trenches are dug 3 ft deep, 5 –8 ft broad and
30 ft long
•Not more than 3 ft depth is recommended
•Located half a mile away from city limit.

19. Procedure
A layer of refuse about 15 cm thick is spread at
the bottom of trench
Night soil is added corresponding to 5 cm
thickness above the refuse
Alternate layers of refuse and night soil
corresponding to 15 cm and 5 cm in thickness
is added till the heap rises to 1 ft above the
ground.
Top layer should be refuse and it should be
covered with mud.

20. Mechanical composting
In this compost is manufactured on a large
scale by processing raw materials.
Refuse is first cleared of salvageable material
like bones, rags, metals likely to interfere with
grinding process
This is then pulverised in a pulverising
equipment to reduce the size of particles to <2
inches.
Mixed with sewage, sludge, in a rotating
machine and incubated under certain
temperature, moisture, aeration.
Entire process is complete in 4 –6 weeks.

21. Manure pits
Problem of refuse disposal in rural area
can be solved by manure pits
Pit is dug in each house hold. Garbage,
cattle dung should be disposed in the pit
and covered with earth after each day
dumping.
In 5 –6 months the refuse is converted
into manure.

22. Burial
Suitable for camps
Trench is dug. Refuse is disposed and
covered with earth at the end of each day.

23. Liquid waste
Sources :
1. Wastewater from kitchen and bathroom
( SULLAGE )
2. Industrial waste water
Should be devoid of excreta.

24. Ill Effects of improper disposal
Waste water is a breeding place for
mosquitoes, Flies, cockroaches
Water pollution
Lowers quality of soil.

25. Sullage disposal
Facilities available can be disposed into
septic tank, under ground sewerage and
drains
Sufficient land is available in house Kitchen
garden can be developed.
Kitchen garden: Takes care of disposal of
house sullage as well as protective edibles
are grown in house.
Soakage pit: In rural area

26. Soakage pit
Ideal for sullage disposal in rural area.
Pit is dug at a strategic point in courtyard of house.
Sullage from kitchen and bathroom is admitted into the
pit.
It should be rectangular in shape 1
½
cubic meter.
Filled from bottom to top with large stones, brick and
gravel.
Largest size at bottom most layer and gradually
smaller size as layers are laid towards top.
Top most layer is gravel and sand.
Pit is covered with bamboo matting

27. Soakage pit
Sullage contains fatty substances from
kitchen and bathroom.
This interferes with functioning of soakage
pit in winter season.
Grease should be removed by installing
grease trap made of tin containing straw and
grass.
Should be periodically replaced every
fortnight when it gets clogged with fats.
No replacement needed in summer season
as fats do not solidify.

28. Functioning of soakage pit
Sullage passes through grease trapwhere
fats are strained.
Sullage gets surface for attachment around
stones, bricks etc where
1. Biological degradationof waste occurs
2. While straining through pitmechanical
filtrationtakes place
3. Water gets evaporated
4. Water percolatesinto the ground

30. Compositing –Manure pit

32. There are two types of waste water generated. These are
Greywater is waste water from bathroom, washing of
clothes and kitchen. Depending on its use, water can
require less treatment than black water and generally
contains fewer pathogens. Treated water can be reused
for garden watering, fodder raising and kitchen
gardening
Black water is water that has been mixed with waste
from the toilet. Black water requires biological or
chemical treatment and disinfection before re-use.
Type of Waste Water

33. Soak Pit
Soak pit is a dug out pit filled with stones or
preferably over burnt bricks. The large numbers of
stones or bricks increase the surface area over which
biological and chemical action takes place. The water
seeps into the ground and reduces danger of polluting
the ground water sources.
Applicability
Houses without adequate space for kitchen garden.
Action
House owner can construct the pit himself by getting
the information of the design.

34. Description
Step 1
Excavation of 1m x 1m x 1m pit.
Step 2
Filling of 1m x 1m x 1m fit by boulders from bottom
250mm by 125mm to 150mm boulders; 2nd 250mm layer
by 100mm to 125mm size boulders; 3rd 250mm layer by
50 to 75mm size boulders.
Precautions
• Boulder should be firm (No morum boulders)
• Fill the pit by boulders very loosely
• Brick bats and sand should not be used as filling materials.

35. Step 3
Place the 225mm earthen pot (or plastic container) over the last
layer of the boulders.
Step 4
• Lay twigs (25mm thick) over the top 250mm boulders of size 50
to 75mm size
• Take a gunny bag, tear it out to make it a bigger piece and lay over
the twig (25mm thick) (Remember to make a hole in the gunny
bag appropriately to place the earthen pot.)
• Give one more layer of twig (25mm thick) over the torn portion
of the gunny bag.
Step 5

36. Put a layer of mud over the top twig layer.
Step 6
Put some dry soil over the layer of mud; 225mm to 250mm.
Step 7
Make chamber of size 200mm x 200mm around the 225mm
earthen pot and plaster at the inner part of the chamber,
20mm thickness (1:4) and finish it with cement.
Step 8
Connect the bathroom (water) chamber with a 50mm size
diameter non-pressure PVC pipe.
Step 9
Cover the chamber with suitable lid (e.g. wooden plank or a
tile).
Making a filter out of earthen/

37. Advantages
This is the cheapest
technology for
management of water
at household level
Prevents grey water
stagnation
Prevents vector
breading.

43. Solid Waste Incinerator System-Dholka,
Gujarat

44. Integrated Solid Waste Management
Reduction of quantity (Waste
Management Hierarchy)

45. Collection bins

46. Open burning

47. Need for Solid Waste Management
Related to Public Health:
Public Health threats and outbreak of diseases
primarily due to:
??????Poor sanitation condition
??????Waste handling
??????Disposal facilities
About 22 human diseases are linked to improper
solid waste management