Abstract:
Production of biogas through anaerobic digestion of organic waste materials provides an
alternative eco-friendly renewable energy source. Anaerobic digestion is a technology widely
used for the treatment of organic waste for biogas production. Therefore, the study was
conducted to investigate the production of biogas from Wild oats co-digested with goat manure
through anaerobic digestion with five treatments. The treatments were made into five treatments
by mixing substrates in different proportions based on their total solid (TS). The five treatments
used for anaerobic digestions were100% of goat manure,70% goat manure with 30% wild oats,
50% goat manure with 50% wild oats, 30% goat manure with 70% wild oats, and 100% wild
oats mix ratios were evaluated under mesophilic conditions (38ºC) using batch digesters in the
Microbiology laboratory of Haramaya University for 30 days of fermentation. In all treatments,
physico-chemical parameters such as total solids, volatile solids, organic carbon, nitrogen, pH
value, and percent of moisture content were measured before and after anaerobic digestion. The
results indicated that the highest pH value (7.18) was observed in 100%GM (goat manure),
whereas the lowest pH value (6.80) was observed in 100%WO with the same percentage of total
solid content. Comparison of pH values between before and after anaerobic digestion showed
that pH values were significantly increased after anaerobic digestion for all treatments.
Similarly, the values of % Total Solid and Volatile Solid showed a decrease from the initial
value. In addition to this, carbon to nitrogen ratios was analyzed; the results revealed that the
highest carbon to nitrogen ratio was observed in 100% WO. In this experimental study, the
result showed that co-digested substrates of the three mix ratios produced a higher amount of
biogas than the two sole. Among the different proportions of mix ratios 30% goat manure +70%
WO showed the highest daily mean cumulative biogas production (1225.33ml) than all other
treatments. Overall the results of this study indicate that the increase in biogas yield and
reduction in volatile solids and total solids can be significantly enhanced when goat manure is
co-digested with Wild oat in a 30%:70% mix ratio.
