Biohydrogen production using an up-flow anaerobic sludge blanket reactor

Sewage sludge was acclimated to establish H2-producing enrichment cultures for converting sucrose (20 g COD/l) into H2 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 H2/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 (Kd) 0.1 day−1 and yield coefficient (Yg) 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.