biogas production potentials from anaerobic co- digestion of food waste and human excreta in jimma university, south west Ethiopia

Abstract

Introduction: Biogas is produced by the anaerobic digestion of biodegradable materials. Codigestion is a simple approach of anaerobic digestion by mixing wastes together in different ratio and proportion.About 2.4 billion people still do not have access to improved sanitation. In Ethiopia the prevalence of diarrhoea is slightly higher for children in households with unimproved sanitation than in households with improved sanitation1.3 billion tons of food is wasted annually across the world. From organic solid waste stream available, food waste accounts 45-70 %. Global food waste ranked the third top methane emitter after China and United States of America. Objective: The aim of this study was to assess biogas production potentials from anaerobic codigestion of food waste and human excreta. Methods: lab based experimental study design was employed. TS, , VS, MC, C/N ratio, fecal coliform and ova of S mansoni were determined before and after AD. pH, temperature, daily biogas and methane content was measured every other day until the end of the experiment. Biogas and methane was measured using water displacement method and 10 % sodium hydroxide solution respectively. The data was entered in excel 2016 version and subjected to analyze of variance using SPSS version 21. Result: The highest reduction of VS was recorded in digestion of co substrates (14.5-20 %) compared to digestion of mono substrates (7.6-9.9 %). Optimum C/N ratio was obtained from T2, T3 and T4 (21.6-28) compared to T1 and T5 (34.6 and 13.4. The result showed that biogas production was started from second day and reached zero at day 40(T1), 42(T5) and 44 (T2, T3, T4). Two and half times higher biogas yield was obtained from co digestion of FW and HE compared to mono digestion of food waste and human excreta. The highest and lowest percentage of methane was obtained from T3 (72.5%) and T5 (57.7%). 1.07± 0.4 log CFU/ml (45.5%) of fecal coliform were removed after 44 days retention time. S mansoni was completely removed after 44-day retention time anaerobic digestion. Conclusion and Recommendation: The highest biogas and methane was produced from co digestion of FW and HE opposed to mono digestion. In order to have more biogas and methane yield co digestion of 50% FW + 50% HE mixture should be applied.