A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1983

In the light of providing cheap and readily available nutrition for fish food production, a study on aerobic composting of water hyacinth on a pilot scale was undertake n. In this work, 20 pilot-size piles of chopped water hyacinth under treatments of varying pile size and moisture levels were composted over periods ranging from 5 to 2 0 weeks. During these periods analyses were conducted on a weekly basis to evaluate the physical and bio-chemicals changes occurring in these piles as degradation proceeded. Three experiments were conducted : (1) piles comparing 1.4, 1.0 and 0.6m heights; (2) piles comparing low range moisture levels of 55%, 65% and 75%; and (3 ) piles comparing high range moisture levels of 75% , 85% and 93% (fresh) . included in the last experiment was a pile mixture of rice straw and water hyacinth at a moisture content of a bout 75% , to ascertain the possibility of eliminating the drying procedure . All treatments were set up in duplicate. At the outset, 1.4 m initial pile height and 70% moisture were considered optimum levels for efficient composting. Five weeks was taken as an adequate composting time to ensure high nitrogen an d phosphorus conservation and a bout 75% decomposition of degradable organics . However, results of a water hyacinth-rice straw mixture , though acceptable , need to be compared with other moisture level treatments.