Speciation of trace metals (Cu, Zn, Ni, Fe and Mn) during rotary drum composting of paper mill sludge
Chemical speciation is a very proficient tool for assessing bioavailability of heavy metals. Thus, this study was carried out to detect the variation in distribution of different fractions (Exchangeable, Carbonate, Reducible, Oxidizable and Residual) of Cu, Fe, Ni, Zn and Mn and also to assess the influence of physico-chemical parameters on chemical speciation during rotary drum composting of primary paper mill sludge (PPMS). Residual fraction was established as the most dominant fraction during speciation. Concentration of Ni was found to be mostly associated with residual fraction. However, though concentration of Cu was not found very high but its bioavailability was prominent. The current study reveals that cow dung addition in optimization can influence the physico-chemical parameters, which in turn decreases the bioavailable fraction (exchangeable and carbonate) of heavy metals during composting.