下水汚泥と都市ごみのゼロエミッション指向型管理

Abstract

Environmental loads in cement production from sewage sludge and tile production from municipal solid wastes (MSW) were assessed using life cycle assessment (LCA) as the examples of waste management directed toward zero emission. Inventory analysis of cement production from sewage sludge shows that consumption of clay, iron material and energy, and CO2 emission are reduced. On the other hand, consumption of silica stone is increased. Inventory analysis of tile production from MSW shows that consumption of feldspar and pottery stone is reduced. On the other hand, energy consumption and CO2 emission are increased. As impact assessment, change of mass balance in Japan is evaluated in case if zero emission is put into practice. Impact assessment of cement production from sewage sludge shows that 25% of sewage sludge (dry sludge base) and 0.10% of CO2 emission are reduced in Japan. If dewatering process is changed, the effect of zero emission is increased. Impact assessment of tile production from MSW shows that 3.32% of MSW ash is reduced and 0.01% of CO2 emission is increased. If melting process is omitted, increase of energy consumption and CO2 emission is eliminated. Assessment of regional mass balance shows that cement production from sewage sludge is effective in Chugoku, Shikoku and Kyushu area, and tile production from MSW is effective in Gifu prefecture.