Heavy metals in leachate during food waste composting may produce different degrees of pollution hazards and further induce environment costs, when the concentrations of heavy metals exceed the discharging quality standards. Quantitative evaluation of heavy metals' pollution hazards and estimation of such environmental costs are under-represented in the existing literature. This paper uses a logistic function approach to evaluate the extent of pollution hazards of heavy metals such as cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb) and arsenic (As) and to estimate heavy metals' environmental costs in leachate during food waste composting from Minhang food waste treatment plant located in northern Shanghai, China. Major findings of this study are: (1) The pollution hazards rate of Cd amounts to 94.03%, probably because Cd-containing materials such as plastics are mixed with food waste; (2) With the comprehensive pollution hazards rate estimated as 94.48%, the environmental costs caused by heavy metals in leachate during food waste composting amount to US$0.52 per tonne. This magnitude of environmental costs is meaningful and significant, considering that it is equivalent to 2.97% of Shanghai's food waste treatment charges.

The rapid development of China’s economy has led to a sharp increase in the municipal solid waste (MSW). China has promulgated the MSW mandatory classification policy. The implementation effect of such mandatory policy is an important concern to the government, scholars and the public, but has not been extensively studied. This paper explores the implementation effect of such policy through assessing the waste classification behavior of residents based on the Cellular Automata model. The simulation results show that the residents will not adjust their MSW classification behavior during the time period when the mandatory classification policy is not implemented.But when the mandatory classification policy is imposed, the residents will adjust their classification behavior over time from t=100 to t=300.The results indicate that the extent of residents’ participation in waste classification varies by different enforcement intensity .The higher the intensity is, the more rapidly residents’ MSW classification behavior improves.The results also indicate that the extent of residents’ participation in waste classification varies by different urban population size. The larger the urban population size is, the higher the proportion of classification participation is.