Contents of harmful organic materials in calcium phosphate product derived from sewage sludge ash and alkaline wastewater

Abstract

We examined the contents of organotoxic materials in a calcium phosphate product made by alkaline extraction of sewage sludge ash with alkaline wastewater (0.5 mol NaOH L^-1) from electronicfactories in Japan. Generally, raw materials from industrial wastes contain heavy metals and organotoxic materials. However, this method can produce calcium phosphate at high purity, excluding organotoxic substances to below Japanese legislated criteria. Many large industrial corporations in Japan are required to follow the European RoHS Directive and minimize the contents of heavy metals and organotoxic materials in their wastes. Our calcium phosphate product met the criteria for alkyl mercury compounds, cyanide compounds, PCBs, fluorine and its compounds, trichloroethylene, tetrachloroethylene, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloropropene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,3-dichloropropene, benzene, thiram, simazine, thiobencarb, phenols, and 1,4-dioxane. These results show that it is possible to support a sustainable society through agriculture.