Biotechnological process for the treatment of fleshing from tannery industries for methane generation.

摘要

The objective of this study was to accelerate the fleshing digestion process by inoculating with efficient proteolytic bacteria, after which it could be subjected to biomethanation. Tannery sludge was collected from the CETP, Dindigul run by Tamil Nadu Leather Development Corporation and fleshing was obtained from the beam house of Shri Ramajayam Tanners, Dindigul. Slurry preparation were made by mixing liquefied fleshing and biological sludge (secondary sludge) in ratios of 1:1 (T< sub>1), 1:2 (T< sub>2), 2:1 (T< sub>3), 3:1 (T< sub>4) and 3:2 (T< sub>5). A control digester (T< sub>0) was maintained using cow dung and water in the ratio 1:1. Twelve strains were isolated from the enrichment culture technique using cow dung and tannery fleshing. Two isolates (I and II, Pseudomonas fluorescens and Bacillus subtilis) which showed higher proteolytic ability were selected for further studies based on casein hydrolysis and free amino acid liberation during hydrolysis. These isolates were characterized based on their morphological, cultural and biochemical properties. Results of the screening tests showed that the tannery fleshing was completely digested by the isolated proteolytic bacterial strains effectively. In the second phase, investigations were carried out using liquefied fleshing mixed with biological sludge (secondary sludge), cow dung and water for biogas production. For solid organic wastes, the common pre-treatment method is hydrolysis, which liquefies the substrate in a bioreactor before using it as feedstock for biomethanation. It was observed that the cumulative gas production and methane content (63%). Further investigations were carried out and the results indicate that the biologically liquefied tannery fleshing could be effectively used for production of methane at higher rate, compared to raw fleshing. Liquefied fleshing produced three-fold the amount of gas compared to raw fleshing, and methane content was recorded as 64%.