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Vermicomposting is a traditional technology that produces the best quality of compost, but factors such as maturity, presence of heavy metals, etc. need to be tackled prior to agrarian application. The present study investigates the influence of varying biochar dose (2.5, 5, and 10% on a weight basis) on the maturity of compost and heavy metals during vermicomposting of vegetable waste using epigeic earthworm. Biochar amendment notably enhanced the electrical conductivity (up to 2.7 mS/cm), nitrogen content (up to 3.1%), NO 3 -N (up to 630 mg/kg) and nutritional value. The heavy metals, oxygen uptake rate (below 0.96 mg/g VS/day) and CO 2 evolution rate (below 1 mg/g VS/day) were attenuated along with degradation of complex organic crystals as observed in powder X-Ray Diffraction (PXRD) spectra. Furthermore, biochar aid in reducing pathogens (below 1.1 × 10 3 MPN/g dry weight) as inferred from the Most Probable Number (MPN) results as well as degrading the complex organics into simpler compounds as revealed from the Fourier-transform infrared spectroscopy (FTIR) spectra. The present study inferred that the vegetable waste was biologically stabilized through biochar amendment during vermicomposting process with improved nutritional and physico-chemical properties., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Composting is an efficient technology to reduce pathogenic bodies and stabilize the organic matter in organic wastes. This research work investigates an effect of biochar as amendment to improve the composting efficiency and its effect on degradation kinetics, physical and nutritional properties. Biochar (2.5, 5 and 10% (w/w)) were added into a mixture of Hydrilla verticillata, cow dung and sawdust having ratio of 8:1:1 (control), respectively. Biochar addition resulted in advanced thermophilic temperatures (59 °C) and could improve the physical properties of composting process. Owing to addition of 5% biochar as a bulking agent in composting mixture, the final product from composting, total nitrogen increased by 45% compared to the other trials, and air-filled porosity decreased by 39% and was found to be within recommended range from literature studies. Considering temperature, degradation rate and nitrogen transformation the amendment of 5% biochar is recommended for Hydrilla verticillata composting., (Copyright © 2018 Elsevier Ltd. All rights reserved.)