Quantitative evaluation of heavy metals' pollution hazards and estimation of heavy metals' environmental costs in leachate during food waste composting.

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.