Microbe Assisted Generation of Value Added Products from Agricultural Wastes

Abstract

Considering the enhanced energy demand and fossil fuel depletion, there is an intense need to find an alternative of fossil fuels in the form of renewable energy source. This problem can be solved by using agricultural biomass for energy generation via microbial process like anaerobic digestion (AD) and fermentation because it is a renewable source of energy. The fuels generated from biomass are known as biofuels which are the value added products of AD. newlineThe present thesis deals with pretreatment of rice straw (RS) using highly alkaline petha wastewater (PWW) and acidic dairy wastewater (DWW) separately. This pretreated RS was further given secondary pretreatments either using ultrasonic bath or microwave oven or autoclave for maximum sugar release. Compositional changes in RS were compared for all pretreatments and also with untreated RS. PWW and DWW were characterised for various physical and chemical parameters and the results were compared. Various characterisation techniques i.e., SEM, FTIR, EDX and XRD analysis were used for characterisation of RS before and after each pretreatment. Statistical tool, one way ANOVA was used to optimise the sugar release from RS after microwave and autoclave pretreatment. Rice straw and PWW or DWW were subjected to AD with mixed microbial source derived from cow dung and soil separately for production of methane, bioethanol, bio-methanol and volatile fatty acids. Soil culture resulted in higher amount of methane in all reactors as compared to cow dung culture and maximum methane yield was 303.20 L/kgRS for PWW pretreated RS. Bioethanol yield was enhanced by each pretreatment and found maximum for autoclaving (1951 mg/LReactor volume) in the reactor with DWW inoculated with cow dung culture. Bio-methanol was also affected by each pretreatment process and found to be maximum (36.82 mg/LReactor volume) in case of ultrasonication in the reactor with PWW inoculated with soil culture. Statistical tool, principal component analysis (PCA) was applied on the results obtained from batch reactors to check the significance and variability of the results. Bacterial isolation was done and three fermentative bacterial strains were identified as Bacillus cereus DK-01, Citrobacter sp. DK-02 and Citrobacter koseri DK-03 which were responsible for bioethanol production in the present study. newline newline