Mesophilic and thermophilic alkaline fermentation of waste activated sludge for hydrogen production: Focusing on homoacetogenesis

Jingjing Wan, Yuhang Jing, Shicheng Zhang, Irini Angelidaki, Gang Luo

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The present study compared the mesophilic and thermophilic alkaline fermentation of waste activated sludge (WAS) for hydrogen production with focus on homoacetogenesis, which mediated the consumption of H2 and CO2 for acetate production. Batch experiments showed that hydrogen yield of WAS increased from 19.2 mL H2/gVSS at 37 °C and pH 10–80.1 mL H2/gVSS at 55 °C and pH 10. However, the production of volatile fatty acids (mainly acetate) was higher at 37 °C and pH 10 by comparison with 55 °C and pH 10. Hydrogen consumption due to homoacetogenesis was observed at 37 °C and pH 10 but not 55 °C and pH 10. Higher expression levels of genes relating with homoacetogenesis and lower expression levels of genes relating with hydrogen production were found at 37 °C and pH 10 compared to 55 °C and pH 10. The continuous experiment demonstrated the steady-state hydrogen yield of WAS was comparable to that obtained from batch experiments at 55 °C and pH 10, and homoacetogenesis was still inhibited. However, the steady-state hydrogen yield of WAS (6.5 mL H2/gVSS) was much lower than that (19.2 mL H2/gVSS) obtained from batch experiments at 37 °C and pH 10 due to the gradual enrichment of homoacetogens as demonstrated by qPCR analysis. The high-throughput sequencing analysis of 16S rRNA genes showed that the abundance of genus Clostridium, containing several homoacetogens, was 5 times higher at 37 °C and pH 10 than 55 °C and pH 10.
Original languageEnglish
JournalWater Research
Volume102
Pages (from-to)524-532
Number of pages9
ISSN0043-1354
DOIs
Publication statusPublished - 2016

Keywords

  • Alkaline fermentation
  • Fermentative hydrogen production
  • Homoacetoogenesis
  • Mesophilic
  • Thermophilic
  • Waste activated sludge
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Ecological Modeling
  • Alkalinity
  • Carbon dioxide
  • Fatty acids
  • Fermentation
  • Gene expression
  • Genes
  • Polymerase chain reaction
  • RNA
  • Volatile fatty acids
  • Waste activated sludges
  • Hydrogen production
  • Clostridium

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