Feasibility of vermicomposting of dewatered sludge using Perionyx excavatus earthworm

Abstract

India has a large network of pulp and paper mills of varying capacity. On an industrial scale the sludge from paper and pulp mills isdisposed of either as landfill or incinerated. Both methods result in the loss of a valuable resource and have obvious environmental andeconomic disadvantages. The solid waste from pulp and paper mills is a source of organic matter and its proper disposal and managementis the responsibility of the industry. As composting/vermicomposting could be used to transform this waste trials were carried out todetermine the feasibility of converting dewatered sludge (DS) into a value added end product using an earthworm, Perionyx excavatus. Thevermicomposting of the waste resulted in an increase in its electrical conductivity (EC), ash content, total nitrogen (TN), total phosphorous(TP) and available phosphorous (AP), respectively, and a decrease in total organic carbon (TOC ), biochemical oxygen demand (BOD),chemical oxygen demand (CO D), oxygen uptake rate (OUR) and evolution of carbon dioxide (CO 2). Overall, the best treatment was T5 inwhich there was a 76.1% increase in TP, 58.7% in TN, 74.5% decrease in TOC , and a reduction of 6.7 fold in the production of CO 2 and 10.7 foldin BOD, respectively. Our trials demonstrate that vermicomposting using an epigeic earthworm, Perionyx excavatus, is an alternate andenvironmentally safe way of recycling paper mill sludge if it is mixed with an appropriate amount of cow dung and food processing waste.Overall T5 was the best combination of paper mill sludge and waste for vermicomposting followed by T3, T2, T4 and T1, respectively.