Title: Enhanced anaerobic digestion of tannery primary sludge using pre-treatment techniques

Authors: Vineetha Antony; P.C. Sabumon; S.V. Srinivasan

Addresses: ECC Division, L&T Ltd, Chennai 600-089, India ' Environmental Engineering Division, School of Mechanical and Building Sciences, VIT University, Chennai Campus, Vandalur-Kelambakkam Road, Chennai 600-127, India ' Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai 600-020, India

Abstract: To reduce the organic fraction of tannery primary sludge, which is classified as hazardous waste in India, batch anaerobic digestion was done at 10% solids concentration in non-mixing condition and at room temperature (28°C to 40°C). To enhance the rate of sludge hydrolysis during anaerobic digestion, the various pre-treatments like autoclaving, thermal treatment, alkali treatment, and biological sulphate reduction were done. Evaluation of the pre-treatments indicates that thermal pre-treatment of the sludge at a temperature of 170°C for 60 minutes enhanced the anaerobic digestion with an increased methane yield (50%) and was the best pre-treatment. Further, optimisation of pH and COD/VSS ratio of the feed, enhanced anaerobic sludge digestion and resulted in approximately 50% removals of soluble COD and VSS. The results presented in this study can help to choose the best pre-treatment route for effective anaerobic digestion of hazardous primary sludge prior to its disposal in landfills.

Keywords: biological sulphate reduction; enhanced anaerobic digestion; pre-treatment; landfills; sludge hydrolysis; tannery primary sludge; hazardous waste; India; autoclaving; thermal treatment; alkali treatment; waste disposal; COD; chemical oxygen demand; VSS; volatile suspended solids; tanneries.

DOI: 10.1504/IJEWM.2016.080260

International Journal of Environment and Waste Management, 2016 Vol.18 No.1, pp.24 - 42

Received: 29 Oct 2015
Accepted: 23 Jun 2016

Published online: 09 Nov 2016 *

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