Influence of seed sludge and pretreatment method on hydrogen production in packed-bed anaerobic reactors

Several studies have reported on the effects of inoculums source and pretreatment on biological hydrogen production. However, there have been few studies on continuous reactors. This paper investigated the influence of different seed sludge sources and pretreatment methods on biohydrogen production in up-flow anaerobic fixed-bed reactors fed with sucrose. The following inoculum sources were included in the study: (1) anaerobic sludge from an up-flow anaerobic sludge blanket (UASB) reactor used to treat poultry slaughterhouse wastewater (Sl), (2) anaerobic sludge from a UASB reactor used to treat swine wastewater (Sw) and (3) autofermentation (A). Heat (He) and acid (Ac) shock were used to increase hydrogen production and suppress hydrogen consumption. The average hydrogen yields (HY) in the experiment were 2.1 (A), 2.0 (SlHe), 2.0 (SlAc), 1.0 (Sl), 1.0 (SwAc), 0.7 (SwHe) and 0.7 (Sw) mol H₂ mol⁻¹ sucrose. Although heat shock produced the maximum HY value (SlHe), acid pretreatment (SlAc) resulted in more stable hydrogen production with the largest average value, which could be an advantage of using pH shock. The autofermentation process presented HY values similar to those produced with SlAc and SlHe, making it a suitable seed sludge for biohydrogen production because pretreatment was not required.