Production of ethanol and bio-chars from Pakistani ligno-cellulosic biomasses

ABSTRACT

The objective of this study was the production of ethanol from two locally available lingo-cellulosic biomasses: rice hulls and wheat straw. Both biomasses were ground to a particle size of 2 mm and pretreated with 2.5% solution of NaOH and the dried masses were individually subjected to enzymatic hydrolysis using cellulase enzyme in buffer solutions. Fermentation of the hydrolyzed products was carried out by using saccharomyces cervices under anaerobic conditions at 35°C for three days of incubation period. The rice hulls and wheat straw produced 15.22 mg/ml and 25.02 mg/ml ethanol, respectively, (on the last day) with appreciable yields. The two bio fermentation residues were used for the production of bio using fixed-bed pyrolysis. At the optimum temperature of chars 600°C, the bio-char products from rice hulls contained 56.15% fixed carbon and 40.88% volatile matter (VM) with a gross calorific value of 7513 Kcal/Kg, whereas bio-chars from wheat straws contained 53.69% fixed carbon, 45.19% VM, and a gross calorific value of 7123 Kcal/Kg. Both bio-chars appear to be good value added products for fuel applications, activated carbon production, and carbon dioxide sequestration.

KEYWORDS:

• Ethanol
• fermentation
• ligno-cellulosic biomass
• pyrolysis
• bio-chars

Acknowledgments

The authors are thankful to Rubina Nelofer, Zill-e-huma, and Mahwish Irum from Food and Biotechnology Research Center of PCSIR Laboratories, Lahore, for their substantial assistance in the research work.