HYDROLYSIS KINETICS IN ANAEROBIC DIGESTION OF LEATHER FLESHING ENHANCED BY LIPASE AND SEQUENTIAL ENZYME PRODUCTION USING FLESHING FATC.H. RESHMA AND P. SHANMUGAM
This paper describes the hydrolysis kinetics of leather fleshing waste using lipase for enhanced biogas production. The batch biochemical methane potential test was carried out in laboratory to estimate its reaction kinetics. The dual application of fleshing waste as substrate was used to produce a crude lipase and the same was used for enhanced biogas production at increased hydrolysis rate constant. The crude lipase was produced using Aspergillus brasiliensis in submerged fermentation was characterised by molecular weight determination and FTIR analysis. The lipase activity was optimised for the parameters like pH, temperature and activity in different substrates. The activity was high at pH 7-8 range, temperature was in the range of 30-40 °C and the activity was high in olive oil with 565 U/mL. The molecular weight determination of the ammonium sulphate precipitated lipase was found to be 50 KDa and the amide bond peak between the wave number ranges from 1600-1700 cm-1 in the FTIR spectrum confirms the enzyme produced is lipase. The maximum lipase activity using fleshing oil as substrate was 140 U/mL. The Vmax and Km determined by Line weaver Burk plot values were 116.28 g/L min-1 and 0.233 g/L .The pH optima for maximum gas production were recorded as 6.5. The hydrolytic rate constant model of the enzyme is performed using contios and first order kinetics. Maximum enzymatic hydrolysis rate constant for fleshing was measured and it was found to be 0.33 day-1. A significant level of biogas yield of 1.65 times was noticed in the enzyme hydrolysis than the normal hydrolysis. This study recommends the production and usage of lipase from leather fleshing for increased hydrolysis rate constant which enhances the biogas yield thereby a sustainable solution for solid waste management in tanning industry.
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