Effect of biostabilization on the release potential and speciation of heavy metals in municipal solid waste

Abstract

Biostabilization prior to landfilling of municipal solid waste (MSW) has been developed to reduce leachate pollution and increase landfill capacity and stability. Leaching tests were used in this study to examine the effect of biostabilization on the release potential and fate of heavy metals in MSW. The speciation of heavy metals in leached MSW and leachates, and their distribution in different molecular weight (MW) fractions of organic matter in leachate were studied. The results showed that a 44-day biostabilization period could lower the release potential of Pb, Cr, Cd, Cu, and Zn in MSW by 50 to 84%. With the exception for Zn, biostabilization tended to decrease the percentages of the metals in the leachate organic fraction with MW < 1 kDa, but increase those of metals associated with organic colloids and high-MW fractions. Therefore, the effects of biostabilization on the behaviour and fate of Pb, Cr, Cd and Cu in leachate would vary in treatment facilities that use different methods and in the natural environment. Biostabilization only slightly affected the behaviour and fate of Zn, due to an insignificant variation in the speciation and distribution of Zn in different MW fractions. In addition, the aerobic and hydrolytic-aerobic biostabilization processes showed similar release potential, speciation, and distribution of heavy metals in different MW fractions.