Evaluation of the ecotoxicity of solid wastes using rapid leaching test and bioassays

A rapid leaching test (RLT) involving the use of ultrasonic irradiation was developed. The applicability and suitability of different leaching procedures for solid wastes were evaluated in terms of the leached concentration of heavy metals and total organic carbon and the ecotoxicity potential of the solid wastes. Solid wastes, including incineration ash and sludge, were used. We performed the RLT and the Japanese standard leaching test (JLT-13) to evaluate the ecotoxicity of the solid wastes. The leaching test samples were analyzed using 3 different bioassays. A higher concentration of heavy metals was obtained by the RLT than by JLT-13. The concentrations of organic compounds leached by the RLT correlated well with those of the organic compounds leached by JLT-13. These results indicate that the RLT developed in this study is a useful method to estimate the leachability of heavy metals and organic compounds in solid waste samples. Although the 50% effective concentration (EC(50)) values of the RLT and JLT-13 solid waste eluates derived by a human cell-based bioassay were slightly different, the EC(50) values of these eluates derived by 2 other ecotoxicity tests correlated well.