Abstract

The effect of varying pH on biogas yield of cow dung was evaluated using three (3) different tin digesters maintained at pH of 4.52, 6.80 and 8.52 representing acidic, neutral and alkaline range respectively. The digesters were operated at mesophilic temperature conditions and hydraulic retention time of 21 days. For each set up, slurries were prepared using a ratio of 1:7 for cow dung and water respectively. The daily biogas yield (ml), weekly cumulative biogas yield and cumulative biogas yield of the different digesters were recorded. The results showed that daily biogas yield was higher in pH of 8.52 while acidic (pH 4.52) has the lowest biogas yield. Cumulative biogas yield (ml) revealed that alkaline pH has the highest biogas yield of 2850 ml while neutral and acidic pH has 2410 and 1300 ml of biogas respectively. The trend of biogas generation in the digester set up revealed that biogas generation starts 24 h after set up in alkaline pH while delayed biogas production was recorded in acidic pH for 8 days. Overall, biogas generation in all the digester set up increase continuously with the last week (14-21 days) yielding the highest biogas yield in all the 3 pH ranges. The aim of this research is to determine the effects of varying pH on biogas generation using cow dung with a view to find out the optimum pH value that produce maximum biogas yield through Prepare different slurry, measure and vary the pH value of the slurry before and after digestion, determine the effects of different starting pH of slurry on daily yield of biogas generation using cow dung and determine the effects of different starting pH of slurry on cumulative yield of biogas generation using cow dung.