An innovative multistage anaerobic hythane reactor (MAHR): Metabolic flux, thermodynamics and microbial functions

Buchun Si, Hao Yang, Sijie Huang, Jamison Watson, Yuanhui Zhang, Zhidan Liu

Research output: Contribution to journalArticlepeer-review


Biohythane production from wastewater via anaerobic fermentation currently relies on two-stage physically separated biohydrogen and biomethane reactors, which requires closed monitoring, the implementation of a control system, and cost-intensive, complex operation. Herein, an innovative multistage anaerobic hythane reactor (MAHR) was reported via integrating two-stage fermentation into one reactor. MAHR was constructed using an internal down-flow packed bed reactor and an external up-flow sludge blanket to enhance microbial enrichment and thermodynamic feasibility of the associated bioreactions. The performance of MAHR was investigated for 160 d based on biogas production, metabolic flux and microbial structure in comparison to a typical anaerobic high-rate reactor (up-flow anaerobic sludge blanket (UASB)). A biohythane production with an optimized hydrogen volume ratio (10–20%) and a high methane content (75–80%) was achieved in the hythane zone (MH) and methane zone (MM) in MAHR, respectively. In addition, MAHR showed a stronger capability to accommodate a high organic loading rate (120 g COD/L/d), and it enhanced the conversion of organics leading to a methane production rate 66% higher than UASB. Thermodynamic analysis suggested that hydrogen extraction in MH significantly decreased the hydrogen partial pressure (<0.1% vol) which favored acetogenesis in MM. Metabolic flux and microbial function analysis further supported the superior performance of MAHR over UASB, which was primarily attributed to enhanced acetogenesis and acetoclastic methanogenesis.

Original languageEnglish (US)
Article number115216
JournalWater Research
StatePublished - Feb 1 2020


  • Biohythane
  • Metabolic flux
  • Methane
  • Microbial structure
  • Multistage anaerobic hythane reactor
  • Thermodynamics analysis

ASJC Scopus subject areas

  • Water Science and Technology
  • Ecological Modeling
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Civil and Structural Engineering


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