抄録
A chemical behavior of cadmium in sanitary landfill layer was studied by investigating timevariations of the total concentration of dissolved cadmium, [Cdt] in leachate from lysimeters. One of two kinds of solid waste, artificial refuse (pseudo mixed refuse) and incinerator residue, was packed in each lysimeter and three experimental conditions, semiaerobic and unsaturated, anaerobic and saturated with seawater, and anaerobic and unsaturated were employed, that is, six lysimeters were experimented. In all the lysimeters, a rapid decrease of [Cdt] was observed. It was found that such decrease resulted from Cd 2+ precipitation reaction with S2- which was supplied by both biological decomposition of protein and reduction of sulfate. A model for calculating time-variation of [Cdt] was proposed, in which the production rate of S2- and CdS precipitation equiliburium were considered. The model could explain the decrease of [Cdt] by properly choosing the effective coefficient γ which is the ratio of S2- involved in CdS precipitation reaction to S2- produced.
