Biohydrogen production with anaerobic sludge immobilized by ethylene-vinyl acetate copolymer

A novel synthetic polymer (ethylene-vinyl acetate copolymer; EVA) was used to immobilize acclimated sewage sludge for H2 production under anaerobic conditions. Using sucrose as the sole carbon substrate, the resulting EVA-immobilized cells achieved an optimal H2 production rate (vH2) of 488 ml H2/g VSS and the best substrate-based yield (YH2/sucrose) of 1.74 mol H2/mol sucrose. Operation at a temperature of 40 °C resulted in the most efficient H2 production. Acclimation of the sewage sludge allowed up to 3-fold enhancement on the performance of H2 production. Kinetic studies show that a Monod-type model is able to describe the dependence of specific H2 production rate on sucrose concentration. The immobilized cells maintained stable and efficient H2 production during 15 repeated runs, indicating excellent durability and stability of the immobilized-cell system. The composition of soluble metabolites was found to be a reliable indicator for the efficiency of biohydrogenation.