Continuous hydrogen production using upflow anaerobic sludge blanket reactors: effect of organic loading rate on microbial dynamics and H₂metabolism

Abstract

BACKGROUND Enriching hydrogen (H2)‐producing bacteria by suppressing methane‐ producing microorganisms is a critical step in continuous biological H2 production. Selective inhibition of methanogens can be achieved by varying the organic loading rate (OLR) in continuous reactors. In this study, continuous H2 production was examined using mixed anaerobic cultures fed glucose in upflow anaerobic sludge blanket reactors (UASBRs) operating at 37°C and at pH 5.0 by varying the OLR at a constant hydraulic retention time. RESULTS A stable H2 yield of 1.64 ± 0.04 mol mol−1 glucose was obtained at OLRs from 8.6 to 12.8 g COD L−1 d−1. Increasing the OLR increased the hydrogenase flux and suppressed methanogenesis. At high OLRs, high acetate and solvent production were associated with Clostridiaceae and Ruminococcaceae while at low OLRs, the presence of Synergistaceae and Propionibacteriaceae were related to the production of propionate and other reduced byproducts. CONCLUSION This study successfully demonstrated continuous H2 production using bench‐scale UASBRs fed glucose. Understanding the OLR effect on H2 production and microbial interaction is important in the full‐scale operation of H2 production facilities using low value feedstocks such as switch grass, corn stover and shorghum. © 2016 Society of Chemical Industry

Activated sludge bacterial communities of typical wastewater treatment plants: distinct genera identification and metabolic potential differential analysis

“…And some Microbacteriaceae strains can even grow in a heavy metal contaminated environments (Corretto et al 2017 ). Ruminococcaceae are able to produce mixed byproducts containing H 2 , ethanol, acetate and degrade Methyl tert-Butyl Ether (MTBE) (Liu et al 2016 ; Veeravalli et al 2017 ). Although we also know nothing about genus B - 42 , but as for Trueperaceae , it has been reported as a hydrocarbon-bearing microorganism where some strains from Trueperaceae have been seen to have the ability to grow under multiple extreme conditions such as high alkalinity, moderately salinity, high temperatures, and are even found t o be present and remarkably resistant to ionizing radiation (Corretto et al 2017 ; Qian et al 2017 ).…”

Microbial cell immobilization in biohydrogen production: a short overview

“…The UASBR showed better performance with a biohydrogen production rate of 2.7 H 2 L/L/d at HRT of 3 h. Meanwhile, the CSTR produced a biohydrogen production rate of 0.5 H 2 L/L/d at HRT of 24 h. Moreover, the UASBR was more resistant to cell washout as compared with CSTR [86]. Veeravalli et al [119] investigated the effect of an organic loading rate on biohydrogen production using granulated UASBR and attained a high biohydrogen yield of 1.64 mol H 2 /mol glucose at 12.8 g COD L À1 d À1 . Increasing the organic loading rate from 8.6 to 12.8 g COD/L/d favored biohydrogen-producing hydrogenase enzymes and suppressed the biohydrogen-consuming methanogenic archaea [119].…”

“…Veeravalli et al [119] investigated the effect of an organic loading rate on biohydrogen production using granulated UASBR and attained a high biohydrogen yield of 1.64 mol H 2 /mol glucose at 12.8 g COD L À1 d À1 . Increasing the organic loading rate from 8.6 to 12.8 g COD/L/d favored biohydrogen-producing hydrogenase enzymes and suppressed the biohydrogen-consuming methanogenic archaea [119]. It is important to maintain a large population of biohydrogen-producing microorganisms to ensure high process yields.…”