The comparison of gas generation between original pH (4.6) and controlled pH of 7.0 was conducted, since the pH value was important for biogas production. The amount of gas in system of pH 7.0 was generated faster and much more gas than that in uncontrolled pH system (Fig 2). The amount of gas was significantly increased from 11 liters within 28 days in original pH system to 50 liters within 10 days in the controlled pH system. Influence of pH to biogas system was previously mentioned by McCarty that the methanogenesis process in biogas production was preferred pH at 6.5- 7.5 [4]. However, the different result was also reported that the system performance to bioconversion of pulp and paper mill wastewater to methane did not fall down even of pH was lower than 6.0 [6].