We used a hydrogen (H2)-based biofilm to treat a groundwater contaminated with perchlorate (ClO4-) at ∼10mg/L, an unusually high concentration. To enhance ClO4- removal, we either increased the H2 pressure or decreased the electron-acceptor surface loading. The ClO4- removal increased from 94% to 98% when the H2 pressure was increased from 1.3 to 1.7atm when the total acceptor surface loading was 0.49gH2/m2day. We then decreased the acceptor surface loading stepwise from 0.49 to 0.07gH2/m2day, and the ClO4- removal improved to 99.6%, giving an effluent ClO4- concentration of 41μg/L. However, the tradeoff was that sulfate (SO42-) reduction occurred, reaching 85% conversion at the lowest acceptor surface loading (0.07gH2/m2day). In two steady states with the highest ClO4- reduction, we assayed for the presence of perchlorate-reducing bacteria (PRB), denitrifying bacteria (DB), and sulfate-reducing bacteria (SRB) by quantitative polymerase chain reaction (qPCR) targeting characteristic reductases. The qPCR results documented competition between PRB and SRB for space within the biofilm. A simple model analysis for a steady-state biofilm suggests that competition from SRB pushed the PRB to locations having a higher detachment rate, which prevented them from driving the ClO4- concentration below 41μg/L.

Original languageEnglish (US)
Pages (from-to)3139-3147
Number of pages9
JournalBiotechnology and bioengineering
Issue number12
StatePublished - Dec 2013


  • Biofilm detachment
  • Groundwater remediation
  • Microbial community
  • Perchlorate reduction
  • QPCR
  • Sulfate reduction

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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