Abstract
Recently, many pig farmers have faced the issues of odor suppression and water quality standards for wastewater discharge during the treatment of manure. As a solution to these issues, a small-scale, distributed methane fermentation system was developed and introduced to a pig farm in April 2016. This system had a lower manufacturing cost and was constructed considering the profitably of a medium-sized pig farm in Japan. This study aims at clarifying the carbon and nitrogen flows, power generation from biogas and benefits of the system in view of providing more details about its functionality. The results indicated that 51% of the carbon had been decomposed into biogas, and the denitrification of wastewater treatment unit in the system was functioning as required. In addition, the monthly electricity production was about 9900kWh. When the selling price of the electricity produced by the biogas was 39yen/kWh, it was estimated that the power generated by the system could be sold for 4.6 million yen per year. Therefore, the initial cost could be recovered in less than 11 years.
