Page 180 - Health, Population and Environment Education 9

as well as cow dung and sludge into layers helps to increase temperature in the pit. Once
the pit is full, it is covered by mud and black polythene. It takes (4-6) months time to
prepare compost by this method.

Differences between Aerobic method and Anaerobic method

Aerobic method Anaerobic method
1. The method of preparation of compost 1. The method of preparation of compost
by bacteria in presence of air is called by bacteria in an absence of air is called
aerobic method. anaerobic method.
2. The wastes are simply dumped in a pit 2. The wastes are piled up in layers in a
in this method. pit in this method.
3. There is no use of cow dung and 3. Cow dung and sludge are mixed with
sludge. wastes.
4. The wastes are turned upside down. 4. The wastes are not turned upside
down.
5. The pit is opened. 5. The pit is covered.
6. It takes about 1 month to prepare 6. It takes about (4-6) months to prepare
compost. compost.

iii. Mechanical method
In this method, bigger biodegradable wastes like bones, rotten fruits, vegetables parts,
skin, etc. are broken down into small pieces not more than 2 inches in size by means of
machines. They are mixed with cow dung and sludge and left over. Since the wastes are
made open, there is spreading of bad smell. Then gradually the compost is made. It takes
about (4-6) weeks time period to prepare compost by this method.

iv. Vermi-compost method
The process of converting compost by earth
worms is called vermi-compost method. In this
method, a bamboo basket with a lid, straw, mud
and vermies or earthworms are needed. Initially,
a layer of straw is kept at the bottom of basket
as bedding for earthworms. Then, a layer of cow
dung and mud is placed on the bedding. After that,
500-1000 earthworms are kept on bedding. The
biodegradable wastes are crushed into small pieces Fig: 38
and kept inside the basket as food for earthworms.
The lid of basket is always closed as earthworms are photo-sensitive. The earthworms
consume the wastes and excrete compost. It takes about two months to prepare compost
by this method.

180 GREEN Environment Population and Health Education Book-9