COMPARATIVE EVALUATION OF CUMULATIVE BIOGAS YIELD OF YELLOW YAM BRUTE CO–DIGESTED WITH COW PAUNCH MANURE IN BATCH MODE

Anaerobic digesters were used in a study to compare cumulative biogas yield from yellow yam brute, cow paunch and yellow yam brute co–digested with cow paunch manure. It was found out that the mixture slurry of yellow yam brute mixed with cow paunch (YYB+CP) had the highest cumulative biogas yield of 668.65 mL/TMS than the cumulative biogas yield of 587.86mL/TMS and 307.96 mL/TMS obtained from the single base line substrates of cow paunch and yellow yam brute, respectively within the 35 days hydraulic retention time (HRT). It was also observed that YYB+CP and cow paunch (CP) produced almost equal quantity of cumulative biogas yield of 398.76 mL/TMS within the first 15 days of observation compared with cumulative biogas yield 178.45 mL/TMS produced by yellow yam brute (YYB) within the same HRT. It was also observed that gas production reduced seriously in mono–digested substrates YYB and Cp compared with the co–digestate because of lack of synergistic nutrients. It is generally observed that co–digestion of more than one substrate increase cumulative biogas yield. The trend of cumulative biogas yield at the end of 35 days hydraulic retention time was YYB+CP > CP > YYB. This study is aimed to evaluate the performance of biogas production from yellow yam brute mixed with cow paunch manure, and to compare its cumulative biogas yield with cow paunch and yellow yam brute digested as mono–digestate in batch mode. Keyword: Anaerobic digestion, Biogas, Substrate, Co–digestion, Cow paunch, Yellow yam brute.