Abstract
To introduce a methane production process in a small-scale sewer plant which employ oxidation process or extended aeration activated sludge process, it is effective to gather dewatered sludge from several wastewater treatment plants. In this study, biochemical methane potential (BMP) of dewatered sludge collected from eight small-scale plants was evaluated. BMP remarkably decreased in summer season in lower scale plants, though the variation of BMP in higher scale plants was small. BMP increased remarkably by coagulation\dewatering process. Increasing ratio of BMP did not depend on the treatment process, dewatering devise, and season. As the results of EPS extraction, EPS increased by coagulation/dewatering process. Especially, carbohydrate contents in LB-EPS decreased and those in Total-EPS increased, suggesting that LB-EPS strongly bund to the cell surface, and polysaccharide inside the cell was eluted to EPS fraction by damage of cells. Since the pH value of coagulant solution was low, combination of acid addition and mechanical force might be effective on increase in BMP. These results indicated that coagulation/dewatering process was effective as pre-treatment of methane production of sewage sludge. Collection of sewer sludge after dewatering would be useful to introduce methane production process.
