Backwash intensity and frequency impact the microbial community structure and function in a fixed-bed biofilm reactor

Xu Li, Wangki Yuen, Eberhard Morgenroth, Lutgarde Raskin

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Linkages among bioreactor operation and performance and microbial community structure were investigated for a fixed-bed biofilm system designed to remove perchlorate from drinking water. Perchlorate removal was monitored to evaluate reactor performance during and after the frequency and intensity of the backwash procedure were changed, while the microbial community structure was studied using clone libraries and quantitative PCR targeting the 16S rRNA gene. When backwash frequency was increased from once per month to once per day, perchlorate removal initially deteriorated and then recovered, and the relative abundance of perchlorate-reducing bacteria (PRB) initially increased and then decreased. This apparent discrepancy suggested that bacterial populations other than PRB played an indirect role in perchlorate removal, likely by consuming dissolved oxygen, a competing electron acceptor. When backwash intensity was increased, the reactor gradually lost its ability to remove perchlorate, and concurrently the relative abundance of PRB decreased. The results indicated that changes in reactor operation had a profound impact on reactor performance through altering the microbial community structure. Backwashing is an important yet poorly characterized procedure when operating fixed-bed biofilm reactors. Compared to backwash intensity, changes in backwash frequency exerted less disturbance on the microbial community in the current study. If this finding can be confirmed in future work, backwash frequency may serve as the primary parameter when optimizing backwash procedures.

Original languageEnglish (US)
Pages (from-to)815-827
Number of pages13
JournalApplied Microbiology and Biotechnology
Issue number3
StatePublished - Nov 2012


  • Backwash frequency
  • Backwash intensity
  • Biofilm reactor
  • Microbial community
  • Perchlorate

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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