Management of Municipal Sewage Sludge by Vermicomposting Technology: Converting a Waste into a Bio fertilizer for Agriculture

抄録

This paper reports on the feasibility of utilization of vermicomposting technology using the earthworm Eudrilus eugeniae for managing municipal sewage sludge by conversion into beneficial bio-fertilizer. Sewage sludge was used at various concentrations 1, 5, 10, 15, 20, and 25% to test for avoidance behavior of the earthworm. The mix of sewage sludge with cassava wastes and cow dung was subjected to compost treatment with and without earthworm treatment for 30 days. During the study period data was collected on the surviving earthworms, biomass together with chemical analysis of wastes before and after treatment. The results indicate that 5% concentration of sludge mixed with cassava waste was ideal for Eudrilus eugeniae to treat. There was a decrease in pH, organic carbon concentration, C:N ratio, and an increase in electrical conductivity (EC), nitrogen, potassium and phosphorus concentrations in all the vermireactors. Total Kjeldhal nitrogen (TKN), available phosphorus and potassium concentrations were increased compared to compost without earthworm treatment at 50, 24, and 10% respectively. The heavy metal concentrations (Cr, Cu, Cd, Pb and Hg) in final vermicomposts were lower than in initial feed mixtures. The earthworm biomass was increased 40-90% and could survive 60% from the beginning. Therefore, the present study showed that vermicomposting of municipal sewage sludge into bio-fertilizer is feasible and provides a safe, simple, economic and practical alternative method to resolve the problem of management of sewage sludge.