Toxicity of Municipal Solid Waste Incinerator Fly Ash and the Contribution of Cadmium.

Fly ash from a municipal solid waste incinerator is regulated under the hazardous waste regulation “Waste under Special Control”, according to the Amendment of the Waste Disposal and Public Cleaning Law in Japan, because it contains high concentrations of heavy metals which are available for leaching.To evaluate the toxicity of fly ash, at first, a fly ash leachate was prepared according to the Japanese standard leaching procedure. The chemical analysis of the leachate showed that one of the possibly most toxic substances was cadmium. The toxicity of the leachate and cadmium was determined by algal assay and Daphnia acute toxicity test. The results showed that the leachate was about 10 times more toxic to the growth of algae, and 20 to 30 times more toxic to the survival of Daphnia than expected from its cadmium concentration.The toxicity interaction between cadmium and the other constituents in the leachate was also examined. The toxicity of cadmium showed additive effect with the other constituents in the leachate in algal assay. In Daphnia test, however, cadmium showed antagonistic effect.