3.2. Effect of initial pH on biogas production
The result of effect of initial pH of digester on biogas production in this study is shown in Table 1 pH 7 gave the best biogas yield. This is in agreement with the reports of other authors as shown in Table 1 pH is an important factor for keeping functional anaerobic digestion. A typical pH is in the range of 6.5–7.6 [24]. The accumulation of intermediate acids leads to pH drop during fermentation. In order to maintain stable operation, it is necessary to add bicarbonate or carbonate as an alkalinity buffer to neutralize volatile fatty acids and carbon dioxide [24].