Mumbai University > CIVIL > Sem 7 > Solid Waste Management

Marks: 10 M

Year: Dec 2011

Decomposition and stabilization of organic waste matter is a natural phenomenon. Composting is an organized method of producing compost manure by adopting this natural phenomenon. Compost is popularly useful as organic manure which contains plant nutrients (NPK) as well as micro nutrients which can be utilized for the growth of plants. For obtaining optimum results it should be used in conjunction with chemical fertilizers.

• There are 2 methods of composting:

Bangalore Method:

1. This an anaerobic method conventionally carried out in pits. Initially a layer of coarse municipal solid waste is placed at the bottom of a pit to a depth of 15 to 25 cm and is made 7.5 cm thicker for 25 cm width towards both the edges of the pit.
2. Night soil is put in the depressed portion to a thickness of 5cm and the elevated edges prevent it from draining to the side.
3. A layer of solid waste is put on the top so that the night soil layer is sandwiched between the two layers of municipal solid waste. Solid waste and night soil are put in alternate layers till it rises to a height of 30cm above the pit edge.
4. The final layer of solid waste is atleast 25-30cm thick. The top of the deposited material is rounded off to avoid rain water entering into the pit.
5. After 4-6 months of decomposition the material is stabilized and is taken out and used as compost.

Indore Method:

1. The Indore method of composting in pits involves filling of alternate layers of similar thickness as in the Bangalore method.
2. However, to ensure aerobic condition the material is turned at specific intervals for which a 60cm wide strip on the longitudinal side of the pit is kept vacant.
3. The first turn is manually given using long handled rakes 4-7 days after filling. The second turn after 5-10 days. Further turning is normally not required and the compost is ready in 2-4 weeks.
4. Aerobic composting of solid waste and night soil can be carried out in windows of more or less the same dimensions as the pits. However, aerobic composting in windows is more commonly used while composting municipal solid waste alone.

The various considerations to achieve composting efficiency maximum are:

1. Organisms
2. Use of Cultures
3. Moisture
4. Temperature
5. C/N ratio
6. Addition of Sewage and Sewage Sludge
7. Aeration