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.
