Assessing mobility and chemical speciation of heavy metals during rotary drum composting of Ageratum conyzoides

Abstract

Ageratum conyzoides, a goat weed that has invaded the world with its disparate behaviour through the inherence of heavy metal against the cultivated crops. The present study enrapt on composting of this disparate weed by assessing the heavy metal virulent throughout the composting process. A 550 L rotary drum composter (an In-vessel composting technique) was used for managing Ageratum conyzoides biologically by blending with inoculum and sawdust. It was evident that the substrate’s volatile solids and biological parameters were high and decreased in the final compost product. The first-order decay model was used for biological parameters and volatile solids through adjusted R2 ksBOD (R2=0.975), ksCOD (R2=0.974 and kV S (R2=0.941) respectively. The mass balance concept was utilised to evaluate the dynamics of the rotary drum composting process. The heavy metal virulent was assessed through bioavailable forms, and leachable heavy metals with chemical speciation fractions were carried out in the composting process. Ni and Cd were found predominantly in residual fractions with 99.7% and 99.5% in final day compost. Pb, Cr, Mn, Fe, Cu and Zn were moderately leached in mobile fractions throughout the composting process. The study stipulates the dynamics of heavy metals in the rotary drum composting process and indicates the compositions of every metal in various distinguished chemical fractions.