Microbial community structure of anaerobic sludge for hydrogen production under different acid pretreatment conditions

The effect of different pretreatment methods on anaerobic H₂ production from a sucrose-rich synthetic wastewater was investigated in this work. The substrate utilization, formation of aqueous products, H₂ production and microbial diversity in anaerobic sludge all markedly depended on these pretreatment methods. The highest H₂ production according to the values for the maximum H₂ production rate of 27.57 ml h⁻¹, specific H₂ production rate of 2.962 ml g-VSS h⁻¹, and H₂ yield of 1.617 mol H₂ mol glucose⁻¹ was observed in the H₂ production by the sludge pretreated with butyrate (pH = 2). Correspondingly, the main microbial communities were Clostridium sp. HPB-16, Clostridium sp. HPB-46, Clostridium sp. HPB-2, Clostridium sp. HPB-4, Oxalobacteraceae bacterium QD1, uncultured bacterium clone HPR93, uncultured Olsenella sp. clone J27, and uncultured bacterium clone SR_FBR_E5. This result demonstrates that acid pretreatment such as butyrate could be also as an effective method to enrich H₂-producing bacteria from anaerobic sludge for large-scale biological H₂ production.