Fermentative Hydrogen Production and Bacterial Community Analysis of Immobilized Sewage Sludge

Abstract

A novel anaerobic batch fermentation seeded with immobilized sludge was developed for enhanced fermentative hydrogen production using pretreated sweet sorghum substrate as carbon source. Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approach. Hydrogen production was more efficient with the immobilized-cell system than with the free sludge. When the heat treated and acclimatized sludge's were immobilized, the cumulative hydrogen production enhanced. The batch fermentation was operated at a hydraulic retention time (HRT) of 24 h and an influent substrate concentration of 10–40 g/L. With highest concentration of substrate, the acclimatized sludge produced 15.98 mL of H2/g of substrate. In all the treatments, maximum hydrogen yield was obtained at the substrate concentration of 40 g/L, inoculum volume of 10 g/L, at room temperature and HRT of 24 h. The immobilized beads retained 60% of their activity up to three cycles. The best fermentative hydrogen production performance was eventually dominated by presumably enhanced hydrogen-producing bacterial species identified as Escherichia coli.