Biohydrogen production using an up-flow anaerobic sludge blanket reactor

Abstract

Sewage sludge was acclimated to establish H 2-producing enrichment cultures for converting sucrose (20 g COD/l ) into H 2 in an up-flow anaerobic sludge blanket (UASB) reactor. The operating hydraulic retention times (HRTs) were 24– 4 h . The experimental results indicated that this UASB system could be used for hydrogen production. The hydrogen productivity was HRT dependent and nearly constant at the HRT of 8– 20 h . However, it drastically decreased at an HRT of 4 or 24 h . The hydrogen production rate (HPR) and specific HPR peaked at the HRT of 8 h and drastically decreased at all other HRTs. At an HRT of 8 h , the average granular diameter peaked at 0.43 mm and each gram of biomass produced 53.5 mmol H 2/ day with a hydrogen gas content of 42.4% (v/v). Butyrate and acetate were the main fermentation volatile fatty acids. The anaerobic granule sludge kinetic constants were endogenous decay coefficient (K d ) 0.1 day −1 and yield coefficient (Y g ) 0.1 g VSS/g COD . The mean cell retention time was 22.2 h and the excess sludge discharge rate was 3.24 l/day .