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Central Leather Research Institute (CSIR), India
Posters & Accepted Abstracts: J Fundam Renewable Energy Appl
The concept of bio-refinery has been demonstrated first time in the present study by utilizing the residue after each bio-fuel recovered as a feed stock for further fuel recovery sequentially to produce biodiesel, bioethanol, bio-hydrogen and biomethane. The fat was recovered (80%) from tannery fleshing waste and subjected to lipase based enzymatic transesterification and recovered biodiesel as fatty acid methyl esters (FAME) (60-80 L/kg of tannery fleshing) under optimized pH, catalyst, mixing and reaction conditions. The FFA profile and FAME was confirmed using FTIR. The residue of biodiesel was primarily glycerol, which was further anaerobically co-digested with molasses and recovered crude bioethanol (30â�?�?50 L/L of mixed glycerol and molasses) employed with specific ethanol seed sludge pre-fermented with molasses at an optimized pH of 4.5. Separate acidophilic hydrogenic and methanogenic seed inocula was pre-acclimatized and activated from the preheated STP sludge with appropriate anaerobic nutrients and maintained at optimum pH conditions of 5.5 and 6.5 respectively. Acidogenic/ hydrogenic seed sludge and ethanol residue waste in the mixing ratio of 1:1 was used for biohydrogen production. The maxima hydrogen production was observed in the pH range of 5.5 to 5.7 as 0.3Nm L/gm of VS removed that was coincided with rodshaped bacteria through SEM analysis. The residue after hydrogen production was used to generate methane using separate pre-acclimatized methanogenic seed sludge and the methane maxima was found to be 0.3 Nm.L/gm of VSr,. This was consistent with cocci-shaped microbial SEM structures at the pH range of 6.3 to 6.5 which was confirmed using two stage anaerobic CSTR for ameliorated hydrogen and methane generation at varying organic loading rates (OLR) and hydraulic retention time (HRT). Therefore, this study successfully demonstrated the concept of bio-refinery to extract multiple bio-fuels sequentially from the high fat, carbohydrate and protein rich organic tannery solid wastes to achieve zero solid discharge (ZLD), to reduce greenhouse gas emissions, with high carbon foot prints.