Abstract
The life cycle energy consumption (LEC) and CO2 emission (LCE) of soap made from recycled food-oil waste (FOW) by the S-plant of Kawasaki were compared with those of the following alternative FOW treatments : (A) discharge into the municipal sewage system, (B) disposal as combustible trash after being treated with an oil-solidifying reagent, and (C) disposal as combustible trash after being absorbed in newspaper. An inventory analysis of the production of regular recycled detergent indicated that it is unfavorable with respect to both energy consumption and CO2 emission compared with detergent made from vegetable oil. On the basis of the official data concerning the municipal sewage and garbage treatments of Kawasaki along with several tacit assumptions, the LEC and the LCE per kg of recycled detergent and those of the equivalent amount of oil waste were calculated as follows : (Treatment/MJ/kg CO2) : Recycled soap/ 13/ 1.8; A/ 9.8/ 2.3; B/ 0.7/ 2.2; C (0 % newspaper recycling) /- 1.7/ 2.0; C (100% newspaper recycling) / 8.2/ 6.2.
