Stabilization of Sewage Sludge Using Cow Dung, Poultry Manure and Horse Dung by Vermicomposting

摘要

Toxic concentrations of heavy metals have been reported to be present in STPs as many industries dispose their waste directly in domestic sewers without prior treatment and thus they are carried to the sludge generated during the treatment processes. This study used one such technique of vermi composting for stabilizing the toxic sludge. The work aimed at reducing the heavy metal content (Cr, Cd, Ni and Pb) from aerobic sewage sludge by the vermicomposting method using earthworm Eiseniafoetida with the different activators (Cow Dung, Poultry Manure and Horse Dung) at 50:50 proportion by mass for 105-day period. The results showed that both cow dung and poultry manure are commensurable for causing the decomposition of the sewage sludge and were better than horse dung. And for stabilizing the heavy metals, cow dung acted as the best activator. The lab analysis depicted high values of chromium which made......