Biohydrogen production from food waste and waste activated sludge in codigestion: influence of organic loading rate and changes in microbial community

Abstract

AbstractBACKGROUNDFood waste (FW) and waste activated sludge (WAS) are complementary substrates that improve H2 production by dark fermentation. However, there is little experience in the process performance in the long‐term operation of reactors co‐processing FW–WAS. This study aims to determine the optimal FW–WAS ratio in batch H2 production and then feed this FW–WAS ratio to an anaerobic sequencing batch reactor (SBR) to evaluate the influence of three organic loading rates (OLR) – 15, 22 and 45 g volatile solids (VS) L−1 d−1 – on H2 performance and microbial composition.RESULTSBatch tests showed that the FW–WAS ratio of 90–10 increased 22% of the H2 production compared to the individual FW. In the SBR operation, the OLR significantly influenced H2 performance, reaching the highest productivity of 733 ± 282 mL H2 L−1 d−1 at an OLR of 22 g VS L−1 d−1. The cooperative lactic acid cross‐feeding between Olsenella and Megasphaera resulted in the highest H2 productivity at an OLR of 22 g VS L−1 d−1. OLR promoted the prevalence of different taxa of hydrolytic bacteria, where Enterococcus and Veillonella were positively correlated, with the highest substrate hydrolysis of 50% at an OLR of 15 g VS L−1 d−1. Prevotella, a genus with a wide spectrum of hydrolytic enzymes, was predominant in the SBR operation regardless of the OLR.CONCLUSIONThe SBR operation at OLR of 22 g VS L−1 d−1 improved H2 production by applying a 90–10 FW–WAS ratio. The change in OLR promoted different taxa of hydrolytic species in the SBR; however, Prevotella spp. prevailed at the three OLRs. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).