Abstract
This study focused on the synergistic effect of the addition of sugar beet pulp (SBP) to enhance the anaerobic digestion of primary sludge (PS) based on their mixing ratios and periodic stirring using the batch reactor. Two experiments were performed during this study. Firstly, co-digestion of PS and SBP was conducted using five mixing ratios. The optimal mixing ratio for the greatest methane (CH4) production and volatile solids (VS) removal rate was recorded at a mixing ratio of 70/30, while the minimum CH4 production was observed at a mixing ratio of 0/100 due to an overload. However, the highest CH4 content was observed at a mixing ratio of 50/50. Secondly, five periodic stirring were carried out (using the optimal mixing ratio from the first experiment). The best CH4 production and VS removal rate were recorded at periodic stirring of 8 on/16 off as a result of the best condition conducted for bacteria, while the minimum value was observed at periodic stirring of 2 on/2 off. The best CH4 content was conducted at periodic stirring of 8 on/8 off.