Comparative Study on Biogas Production Potential of Sewage, Slaughterhouse, Fruit-Vegetable Wastes and their Co-digestion

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Addis Ababa University


Currently, 1.5 liters per person per day (De Mes and Stams, 2003) faeces and urine as sewage waste, 45 to 60m3/day SHW and 2 to 3 trucks/day of FVW generated in Addis Ababa. The main objective of this work was to make comparative study on the biogas generation potential of SW, SHW, FVW, and their co-digestion (M) by using wet batch anaerobic digestion technology. Specifically the study investigated how the performance of anaerobic digestion is affected by temperature, retention time, and waste types. The temperature levels used were room temperature, 37°C and 45°C. Wet mesophilic anaerobic digestions of SW, SHW, FVW and co-digestion of their mixture have been investigated. Wastes samples were characterized in terms of TS, VS, pH, BOD5, COD, total nitrogen and C: N ratio as per the existing standards. Biogas produced was characterized using biogas analyzer. The data from the experiment was analyzed and modeled using Design-Expert version 6.0.8 and significance was accepted at 0.05 level of probability (p<0.05). Comparatively, maximum of 63.9, 77.8, 70.0 %CH4 biogas was observed for co-digestion of aforementioned wastes at room, 37°C and 45°C, respectively. This study shows that %CH4 in the biogas increases with retention time until it reaches optimum point and decrease afterwards. It also shows that biogas production increases in the temperature range investigated irrespective of waste types. Maximum methane yields of 0.12 and 0.16 liters per gram volatile solids digestion (lCH4/gVS) was achieved at 37°C from SHW and M, respectively. Similarly, maximum methane yields of 0.09 and 0.13 lCH4/gVS was achieved at 45°C from FVW and SWs, respectively. Keywords: Sewage waste, Co-digestion, Fruit-Vegetable waste, Methane yield



Sewage waste, Co-digestion, Fruit-Vegetable waste, Methane yield