Chemical Engineering Department Environmental Engineering Stream Anaerobic Co-Digstion of Sewage Sludge and Abattoir Wastes to Enhance Biogas Production
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Date
2010-06
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Addis Ababa University
Abstract
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
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Keywords
Biogas; Sewage sludge; abattoir waste; co-digestion