Value-added product recovery from banana plant waste: A sustainable way for development

Abstract

Pakistan being an agriculture country is enriched with abundance of biomass residues from agricultural crops such as wheat straw, rice husk, bagasse, banana plant, etc. that may be used for resources recovery. The banana plant is one of the potential cellulosic material like cotton crop, wood, etc., obtained from agricultural land. Development in the area of bio-conversion offers a cheap and safe method of not only disposal of agricultural residues but may also be used for the production of product, like, ethanol. Ethanol production from cellulosic material is a two stage process. Initially, the cellulosic material is converted to reducing sugar by acid hydrolysis or enzymatic hydrolysis and afterward, production of ethanol by fermentation process. The current work focuses on the optimization of acid hydrolysis and fermentation using Sacchromyces cerevisiae yeast. In the current study, process conditions for acid hydrolysis, i.e., particle size, reaction time, shaking speed, temperature and concentration of acid were studied in addition to fermentation process optimization. In acid hydrolysis, samples of various particle sizes, i.e., 26, 28, 30, 40, 50, and 100 μm, were used. It was found that reduction in particle size enhances the conversion of reducing sugars from banana plant. The optimized conditions for hydrolysis were found to be shaking time 2 h, temperature 80°C, shaking intensity 90 rpm, and solid–liquid ratio 50 g in 300 ml of H2SO4. With 100-μm particle size, optimum yield of Brix (reducing sugar) was obtained (21–24% per 300 ml). pH was adjusted in the range of 4.5–5.2. For the production of ethanol, aerobic fermentation was carried out using S. cerevisiae yeast species. The fermentation reaction was carried out in a 300-ml conical flask. Optimum yield was obtained at 31°C, residence time 8 h, and when shaken at 80 rpm.