Chemical Engineering Department Environmental Engineering Stream Anaerobic Co-Digstion of Sewage Sludge and Abattoir Wastes to Enhance Biogas Production

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


Concerns about the managing of sewage sludge for an ever increasing trends of sewage sludge generation coupled with the complex sludge characteristics is a big challenge for Addis Ababa Water Supply Authority. Accumulation of large volumes of dried sludge (cake) in treatment compound has become common. Since sewage sludge contains toxic pollutants and disease-causing organisms and the failure to properly manage sewage sludge may have adverse effects on human health and the environment. As a result, the city water supply authority has to search for holistic and systematic ways of managing it. In this study, a lab scale batch anaerobic co-digestion of sewage sludge and abattoir wastes under mesophilic condition for 20 days was used to digest sewage sludge taken from Kaliti dump site and reduction in volume of the wastes as a result of anaerobic digestion, production of methane and soil conditioner potential were analyzed. Abattoir wastes were co-digested with sewage sludge so as to enhance its nutrient values. 100% SS, 80%SS:20%WA and 60%SS: 40%AW mix ratio were used to analysis the biogas productivities of different mix ratios and 33.8%, 48.3% and 56.9% methane were obtained for SS alone, 80%SS:20%AW and 60%SS: 40%AW respectively. Reductions in volume of the sludge after digestion were also seen as the mix ratio increases. The obtained results are generally consistent with the data from literature where co-digestion of sewage sludge with other substrates rather than abattoir wastes were used. Key words: Biogas, Sewage sludge, abattoir waste, co-digestion XII



Biogas; Sewage sludge; abattoir waste; co-digestion