It is generally known that pH plays a substantial role in the
biogas yield under different conditions. This is because the
activities of various microbes depend strongly on the pH of the
medium amongst other factors. The best pH values in biogas
production is in the range 6.5-7.5 [25, 26], though some
authors have reported pH values in the range 7.6-8 [27-29]. In
the literature, there are varying reports on the effect of pH on
the biogas yield involving same or different feedstocks. Result
obtained in this study indicate that a pH of 7 gave the best
yield of biogas. This value is in agreement with the reports of
other authors [16, 27, 28, 30-37] as shown on Table 1.