Enhanced Fermentative Hydrogen Production Using Gamma Irradiated Sludge Immobilized in Polyvinyl Alcohol (PVA) Gels

The anaerobic digested sludge was irradiated using gamma ray to enrich the hydrogen-producing microorganisms, and the irradiated sludge was immobilize in polyvinyl alcohol (PVA) gels for enhanced fermentative hydrogen production. The experimental results showed that the cumulative hydrogen production of 144 mL H-2/100 mL day(-1) and hydrogen yield of 1.77 mol H-2/mol glucose was obtained at 35 degrees C and initial pH 9 by immobilized sludge. The immobilized sludge remained active after 10 repeated batch operations, which showed the advantage over the suspended sludge both in the cumulative hydrogen production and hydrogen yield during long-term operation. Different microbial diversity presented in the suspended and immobilized system was observed: rod-shape bacteria dominated on the surface of immobilized cell beads and suspended sludge; spherical and shuttle-shape microbes were prevalent inside the immobilized cell beads. (C) 2017 American Institute of Chemical Engineers