Enhanced bio-hydrogen production from sweet sorghum stalk with alkalization pretreatment by mixed anaerobic cultures

Abstract

Bio-hydrogen production from sweet sorghum stalk using mixed anaerobic sludge was reported in this paper. Batch tests were carried out to analyze influences of several environmental factors on yield of H2 from sweet sorghum stalk under constant mesophillic temperature (36±1°C). The experimental results showed that, for the raw stalk, the cumulative hydrogen yield was 52.1 ml g−1·TVS with utilization percentages of sugars, hemi-cellulose and cellulose in the stalk being 89.12, 15.23 and 13.89% respectively; whereas for the stalk pretreated by 0.4% NaOH solution at room temperature for 24 h, the cumulative hydrogen yield was 127.26 ml g−1·TVS with utilization percentages of sugars, hemi-cellulose and cellulose being 99.17, 53.64, 41.56%, respectively. The hydrogen content in the biogas was about 53% while the methane content was less than 4% throughout the study. Besides hydrogen and methane, the main metabolic products detected were ethanol, propionate and butyrate. The experimental results suggested that the alkalization pretreatment of the substrate plays a crucial role in the conversion of the sweet sorghum stalk wastes into bio-hydrogen by the mixed anaerobic sludge. Copyright © 2009 John Wiley & Sons, Ltd.