The Suitability of Using Vermicomposting for the Stabilization of Septic Tank Waste

An investigation into the viability of vermicomposting septic tank waste was carried out. Progression of the composting process was monitored by analysing a range of chemical and biological parameters (dehydrogenase enzyme activity, Escherichia coli (E. coli), Olsen P, nitrate and ammonium). At the end of the composting period additional parameters were measured such as total C and N, organic matter, pH, soluble P and N, Salmonella spp., Campylobacter spp. and Helminth ova. Dehydrogenase activity and nitrate and ammonia ratios were shown to be useful indicators to determine the maturation of compost. However, reduction in E. coli did not relate well to removal of pathogens such as Campylobacter spp. and Helminth ova. Pasteurising temperatures cannot be achieved during vermiculture as worms are sensitive to thermophile temperatures, thus for wastes containing high levels of pathogens (such as raw sewage or septic tank waste), further treatment may be required to produce a pathogen free compost.