The composting process consists of converting the spent wash into useful manure. This is done with the help of specialized microbial culture or using fresh compost as seed for the micro-organisms. The raw materials required for composting are spent wash, bacterial culture and a filler material. The most common filler material is press mud obtained from the sugar factory.
Composting is a biological oxidation process for decomposing organic material by a mixed microbial population in a suitably warm and moist environment under aerobic conditions. The degradation converts the material to a stable organic fertilizer, which is also a soil improver.
The aerobic composting process involves arranging the press mud (filler material) in 300 to 400 m long windrows of triangular section of about 1.5 m height by 3.0 m. width on impervious ground usually with the help of front end loaders. The windrows are sprayed with a measured quantity of spent wash, in the ratio of 3.5:1 (spent wash to press mud). The ratio will vary depending on the moisture content of the filler materials.