Abstract
Garden waste comprises of 15–18% fraction of total municipal solid waste generated. For composting of garden waste, particle size is an important factor for efficient degradation. The present study investigates role of varying particle size on compost quality. The garden waste was grinded using a shredder into varying size of particles, 0.5–1.5, 1.5-3.0, 3.0-4.5 and 4.5–7.5 cm diameter named as R1, R2, R3 and R4 respectively. 100 kg of garden waste mixed with 20 litre cow-dung slurry and 10 kg fresh compost and feed into the rotary drum for 45 days composting period. Thermophilic phase continued for 7, 8, 4 and 3 days in R1, R2, R3 and R4 reactor respectively. Total volatile solids reduction was 29.10, 31.20, 24.23 and 17.12 %, CO2 evolution rate was 4.92, 4.14, 6.18 and 8.16 mg/gVS/d, C/N ratio was 16.91, 15.05, 18.13 and 20.99, germination index was 92.00, 94.12, 85.21 and 81.20 in R1, R2, R3 and R4 reactor respectively after end of composting period. Reduction of hemicellulose, cellulose, and lignin was highest in R2 drum and lowest in R4. The percentage reduction of acid insoluble lignin was 36, 39, 29 and 27 % and the percentage reduction of acid soluble lignin was 48.85, 52.89, 43.39 and 36.97 % in combinations in R1, R2, R3 and R4 respectively after 45 days. As per analytical hierarchy process, performance of reactors was observed in the following trend, R2 > R1 > R3 > R4. Particle size range 1.5-3.0 cm diameter showed optimum size for efficient composting of garden waste.
Stability and microbial community analysis during rotary drum composting of vegetable waste
