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1. GOVERNMENT COLLEGE
OF ENGINEERING ,AMRAVATI
UNIT 3- DISPOSAL OF SOLID WASTE

2. DISPOSAL OF SOLID WASTE
METHODS:
1. OPEN DUMPING
2. SANITARY LAND FILLING / CONTROLLED TIPPING
3. SHREDDING & PULVERSATION
4. COMPOSTING
5. INCINERATION & THERMAL PYROLYSIS
6. BARGING (IN SEA)

3. 1. Open dumping
Open dumping of solid waste done in low laying areas.It
is comparatively chipper method . It is extensively used
in INDIA.
However it has following DISADVANTAGES :-
1. Public health hazard caused by breeding of flies
,mosquitoes , etc.
2. It causes air pollution
3. Large land is required for disposal of waste.

5. 2. Sanitary Landfill
• Sanitary landfills have largely replaced open dumps.
• The land filling operation is essentially a biological
method of waste treatment since the waste is stabilized by
aerobic as well as anaerobic bacterial process.
• Entire land fill area is divided into smaller portions called
cell
• Refuge is dumped & compacted in layers of about 0.5 m
• When filling becomes 1.5 m it is covered by earth of
about 15cm thick (Daily cover )
• The process will continue till the most lift is piled up, over
which the final cover of good earth of about 0.6 m depth
shall be laid and well compacted.

7. Properly designed Sanitary landfills:
• Prevent water infiltration and leaching of toxic fluids
• (LEACHATE = a liquid that has passed through or emerged
from solid waste and contains soluble, suspended, or miscible
materials removed from such waste)
• Prevent water pollution
• Reduce Vermin and pests
• Reduce smell, toxic gases and fire hazard

8. TO AVOID FORMATION OF LEACHATE :
The CAP system is provided at the top of sanitary land
fill to avoid formation of leachates .
It consist of following layer : -
• 45cm thick compacted clay layer at bottom.
• 15cm thick drainage layer consisting of sand.
• Geotextile filler membrane to protect drain from
clogging .
• 30cm soil layer (Vegetation Layer ) to promote
grassing.

9. ADVANTAGES :-
• Simple & economical
• No residue remain
• Separation is not required
DISADVANTAGES :-
• Dumping Site may not always be available
• Land fill gases become serious environmental
problem
• Leachate is produced ( chlorinated hydrocarbon
, benzene , xylene etc. ) pollute ground water
causes diseases like cholera , typhoid , polio etc.

10. 3.SHREDING & PULVERIZATION
Size and volume reduction is accomplished by shredding &
pulverization
Volume reduce upto 40 %
Also change physical character-odourless , unattractive to
insects
HAMMER MILL- Speed of hammer upto 1500rpm
Uniform size of 25 to 50 mm is obtained.

11. THE BAILING OF MSW :-
The pulverized MSW is converted into
rectangular blocks of size 1.5 m3 weighing 1 KN approx. by
compacting MSW under high pressure (700 kpa) in either
vertical or horizontal presses.

12. 4.COMPOSTING
• Definition : -
Biological method of decomposing solid waste.
It affects under aerobic & anaerobic condition
End product is manure / compost / humus

13. PROCESS OF COMPOSTING : -
 The process starts with Mesophilic bacteria , which
oxidize the organic matter to CO2 & liberate heat.(Temp. 45 C )
 Thermophilic bacteria take over & continue the
decomposition .(Temp. 60 C )
 In about 4 to 5 weeks , the easily biodegradable
fraction gets consumed & the temp. of the compost mass starts
falling .
 Complete stabilization occurs after the compost is
allowed to cure for another 2 to 8 weeks.
 The entire composting gets completed in about 3 to
4 months .volume will be reduced by 50%.
 The final product has earthy smell and dark brown
colour.

14. QUALITY STANDARDS FOR COMPOST
SR.
NO.
PARAMETER CONCEN. NOT TO EXCEED IN mg /kg OF
DRY COMPOST EXCEPT pH & C/N RATIO
1 ARSENIC 10.00
2 CADMIUM 5.00
3 CHROMIUM 50.00
4 COPPER 300.00
5 LEAD 100.00
6 MERCURY 0.15
7 NICKEL 50.00
8 ZINC 1000.00
9 C/N Ratio 20 – 40
10 pH value 5.5 – 8.5

15. Methods of composting
•Indore method
•Bangalore method

16. Indore method
• It uses manual turning of refuse + night soil for its
decomposition under aerobic condition . Layers of vegetable waste
& night soil are alternatively piled in depths of @ 7.5 – 10 cm each
to total depth of 1.5 m in trench or above the ground to form
windrow.
• Windrow are conical in cross section , 50 m in length.
• Waste is aerated by periodically turning in the windrow . It
continues upto 4 –5 weeks.

17. BANGALORE METHOD
•It involves anaerobic decomposition of waste .
•No handling of mass is required .hence cleaner than Indore
method
•The refuse & night soil are piled up in layers in underground
earthen trench (10 x 1.5 x 1.5 m )
•Layer of earth is applied (15cm )
•Considerable heat gets evolved in the process . (temp. 75 c)
•After 4 – 5 months the refuse gets fully stabilized & changes
into brown coloured humus .
•This humus sieved on 12.5 mm sieve to remove stones ,
broken glasses ,etc.

18. 5. INCINERATION & THERMAL PYROLYSIS
Burning of refuse at high temp. in furnace is called
Incineration.
Only combustible matter are burnt and incombustible matter
either left unburnt or separated out for recycling and reuse
before burning solid waste .
Prior separation will reduce load on furnace.
Heat produced during burning of refuge is used in the form
of steam power for running turbines to generate electricity .
Quantity of steam depends upon moisture content in refuse.
Will need stand by diesel unit to obtain constant power.

19. INCINERATION PROCESS

20. ADVANTAGES & DISADVANTAGES
ADVANTAGES:-
•Ensure complete destruction of pathogenic bacteria.
•There is no odour or dust .
•Cost can be recovered by selling steam power & clinkers.
•Less space is required for disposal .
DISADVANTAGES :-
•Costly method
•Transport vehicles are required for disposal.

21. PYROLYSIS
DEFINATION:-
• Upon heating in closed container in oxygen free
atmosphere most of organic substances of solid waste can split
through combination of thermal cracking and condensation
reaction into gaseous , liquid & solid fractions .
• Pyrolysis may be used for reducing the quantities of
sludge produced in a water treatment plant , before their
ultimate disposal . It is endothermic reaction.

23. When organic solid waste is pyrolysed we obtain following
three types of product at different stage or temp. :-
1. Gas stream :- H , CO ,CO2 CH4 and other.
2. Liquid fraction :- tar , oil (acetic acid )
3. Solid fraction :- charcoal (pure carbon + inert material)

24. 6.BARGING (IN SEA)
•It was used in past to dispose refuse by throwing it away into
the sea , after carrying it at reasonable distance from the coast
(16 – 20 km) Sea depth at disposal point should not be less
than 30 m .
•The direction of current should be such as not to bring it back
towards the shore

25. Disadvantages of barging
•The bulky & lighter particle do not settle down & tend to
return to the shores during high tides.
•The movements of ships is difficult during monsoons &
stormy weather.
•It may cause pollution of sea on large scale .