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