The impact of aerobic pretreatment of agro and industrial wastes on their biomethanation potential in Nisargruna technology

Abstract

Anaerobic digestion is among the essential biological techniques used for stabilization of organic sludge from sewage and highly concentrated efflu-ents from food processing industries. It also recycles the municipal solid wastes into compost with simultaneous production of methane. The current study was performed to estimate the biomethanation potential of various agro- and industrial wastes like Jatropha de-oil cake, prawn shells, chicken feathers, bagasse, rice straw and wheat husk by mimicking the conditions in the biphasic Nisargruna biogas plant. A small volume of samples was chemi-cally characterized and allowed to decompose under aerobic and anaerobic conditions to determine the effect of aerobic predigestion (i.e. phase 1 of Nisargruna plant) on final methane production. The biogas produced was quantified by downward displacement of water. The observations indicated that approximately 60-80% methane was produced when Jatropha de-oil cake, prawn shells and rice straw was used. Conversely, the wheat straw and sugarcane wastes showed less methane formation, which may be due to the presence of complex polymers like lignocellulose and silica that considerably reduces the metabolic potential of microorganisms.