The methodology of composting can be
categorized into three major segments—anaerobic composting, aerobic
composting, and vermicomposting. In anaerobic composting, the
organic matter is decomposed in the absence of air. Organic matter may
be collected in pits and covered with a thick layer of soil and left
undisturbed six to eight months. The compost so formed may not be
completely converted and may include aggregated masses.
Aerobic compostingis the
process by which organic wastes are converted into compost or manure in
presence of air and can be of different types. The most common is the
Heap Method, where organic matter needs to be divided into three
different types and to be placed in a heap one over the other, covered
by a thin layer of soil or dry leaves. This heap needs to be mixed every
week, and it takes about three weeks for conversion to take place. The
process is same in the Pit Method, but carried out specially constructed
pits. Mixing has to be done every 15 days, and there is no fixed time
in which the compost may be ready. Berkley Method uses a labor-intensive
technique and has precise requirements of the material to be composted.
Easily biodegradable materials, such as grass, vegetable matter, etc.,
are mixed with animal matter in the ratio of 2:1. Compost is usually
ready in 15 days.
Vermicomposting involves use
of earthworms as natural and versatile bioreactors for the process of
conversion. It is carried out in specially designed pits where earthworm
culture also needs to be done. Vermicomposting is a precision-based
option and requires overseeing of work by an expert. It is also a more
expensive option (O&M costs especially are high). However, unlike
the above two options, it is a completely odorless process making it a
preferred solution in residential areas. It also has an extremely high
rate of conversion, so quality of the end product is very high with rich
macro and micronutrients. The end product also has the advantage that
it can be dried and stored safely for a longer period of time.
