Impact of quantity of paper mill wastes on vermiconversion time and quality of product

Abstract

Vermi-conversion experiment was conducted for comparison the difference of vermicomposting carried out in small scale at research laboratories or at home with vermicomposting usually carried out medium to large scale for commercial purposes. The experimental raw material (substrate) was made by mixing 30 kg dry and powered Paper Mill solid Wastes (PMW) with 15 kg dry saw dust (SD) and 15 kg dry grinded cow dung (CD). Treatment beds were made in triplicate by using 2 kg, 5 kg and 10 kg of this amended paper mill wastes for vermicomposting. The experiment was carried out following initial aerobic decomposition for 14 days and thereafter vermicomposting using Eisenia fetida earthworms. Quality of vermicomposting and composting time did not differ much on change in quantity of substrate since same composition of raw materials were taken and same vermi-conversion procedure was followed. The results clearly indicate that the quality of vermicompost (on an average pH-7.08, organic carbon-16.28%, total nitrogen1.10%, total phosphorus-0.16%, total potassium-0.15%, total calcium-7.66% and total sulphur-0.19%) does not vary with quantity of substrate used either in large scale commercial production or in small scale research experiments in laboratory. The vermicompost from PMW was, however, found quite low in total content of phosphorus, potassium and sulphur. The content of heavy metals was also reduced significantly during vermicomposting in comparison to their amount recorded in paper mill wastes. The bioassay study with bean seeds (Phaseolus vulgaris) showed that there was no significant difference in data on germination of seeds, number of leaves, number of branches, shoots length, etc., confirming no difference in quality of vermicompost prepared from different quantity of paper mill wastes.