Disposal of Garden Waste by Analysing Selected Physico-Chemical and Biological Parameters Using In-Vessel Composting at a Community Level

Abstract

For composting of garden waste, the selection of reactor is an important factor for efficient degradation. The present study evaluates working performance of rotary drum reactor (RDR) and aerated in-vessel (AIV) for composting of garden waste. 500 kg garden waste was mixed with 50 kg cow-dung slurry and 10 kg compost and fed into both the reactors for 45 days composting period. The reactors vary in their system configuration, shape and orientation, blade design, rate of aeration, odour control, leachate production and energy requirements. Rotary drum was rotated daily six times in clockwise and anti-clockwise direction and AIV was rotated daily for 3-5 minutes using motor. Rise in temperature started within 24 hours of composting and reached 65°C (RDR) and 59°C (AIV) on second day itself and thermophilic phase continued for 5 (RDR) and 7 (AIV) days. Moisture content reduction after composting period was 15.25 and 18.45 %, C/N ratio was 16.14 and 13.33, total volatile solids reduction was 23.74 and 29.78 % and CO2 evolution rate was 6.18 and 4.14 mg/g VS/day in RDR and AIV respectively. Reduction of hemicellulose, cellulose, and lignin was more in AIV as compared to RDR. The percentage reduction of acid insoluble lignin was 36.10 and 29.01 % and the percentage reduction of acid soluble lignin was 48.85 and 43.3% in in AIV and RDR respectively. AIV gave better performance for composting of garden waste due to its blade design and structural configuration. The novelty of the present study lies in its approach to empower communities to select best alternative as per their waste generation, budget available, land and labour requirements and behaviour of citizens towards waste.