FERMENTATIVE HYDROGEN PRODUCTION USING GRANULATED SEWAGE SLUDGE MICROFLORA

Sewage sludge microflora was anaerobically granulated in an up-flow anaerobic sludge blanket (UASB) system to investigate its hydrogen production efficiency. The UASB reactor with a height/diameter (H/D) ratio of 7.4 was operated and its hydrogenic characteristics were compared with a report on a lower H/D ratio of 3.8. The substrate, sucrose (20 g COD L -1 ), was fed in a continuous mode. The reactor was operated at a temperature of 35 ± 1 °C, pH of 6.7 and operating hydraulic retention times (HRT) of 24-6 h. Granulated sewage sludge microflora were demonstrated to efficiently produce hydrogen. A proper reactor H/D ratio enhances the efficiency and reactor operation stability. The highest hydrogen production was obtained at 8 h HRT. Each mol of sucrose yielded 2.9 mol of hydrogen with each g of microflora-solids producing 0.1 mol H2 d -1 . This high H/D ratio reactor, as compared with the reported low H/D ratio reactor, had a small biomass concentration variation, constant volatile suspended solids to total suspended solids concentration ratio, constant alkalinity value and high hydrogen production rate.