Utilization of Different Microbes to Enhance the Biogas Production from Banana Stem Juice

Abstract

Overexploitation of nonrenewable energy resources and the problems associated with their unfair utilization have demanded for alternative sources of renewable energy. Lignocellulosic wastes including cereal straws, sugarcane bagasse, and banana stem, etc., have the potential for conversion into future fuel sources. Banana stem juice (BSJ) was extracted and explored for its potential in biogas production. The study found that BSJ can be fermented within 5–7 days using an anaerobic digestion process and is suitable for biogas production. The present study also focused on enhancing biogas production by adding microbial cultures with the substrate (BSJ) during the anaerobic digestion process. Five bacterial species, namely Streptomyces sp., Bacillus subtilis, Pseudomonas aeruginosa, Lactobacillus plantarum, and Desulfovibrio desulfuricans (separately, in combinations and a mixed culture) were investigated to find the efficiency for boosting biogas production. The optimal conditions as microbial dose, pH, retention time, and temperature for getting the highest yield of biogas through the anaerobic degradation process were analyzed. The best results were observed at 5% microbial dose at pH 8. The P. aeruginosa demonstrated the best results among the cultures studied. On adding a 5% dose of P. aeruginosa, at 8 pH and 30°C temperature for a retention time of 5 days, 3,350 mL of biogas containing 75% of methane share was produced from 1L of BSJ. Under the same conditions, chemical oxygen demand (COD) and total organic carbon (TOC) were reduced by 29% and 38%, respectively, in comparison to unfermented BSJ. It was found that the addition of microbial consortia during biogas production significantly improved the methane production and reduced the COD and TOC content.