Economic Analysis of Sewage Sludge Composting on Regional Circular Economy Using Municipal Input-output Table

The economic effects of the composting of current sewage sludge in Iwamizawa city were investigated compared with the effect of disposing of it. Input-output (IO) tables for each operation, composting or disposing, were compiled and the difference in gross value added (GVA) between the two operations was presented. To create the IO tables, Iwamizawa city’s IO table distributed by the Ministry of the Environment and each operating cost based on past records of Iwamizawa city’s spending were used as original data. Economic ripple effects derived from the operating costs were also included in the compiled tables. As a result, the difference in GVA between the two operations was calculated to be 19.6 million yen year, though the difference in the operational costs was 15.7 million yen year. The use of the sludge dryer was indicated to be a subject of discussion regarding the sustainability of the composting operation. The composting operation can encourage regional demand as local industrial sectors are participating in the operation, and it might lead to larger regional economic ripple effects. The demonstrated analysis could predict an increased amount of GVA, indicating a regional profit. It would be effective for local project assessment.