Hexavalent chromium removal in two-stage bioreactor system

Hai Shen, Yi Tin Wang

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


A two-stage bioreactor system was used to reduce Cr(VI). Escherichia coli ATCC 33456 cells were aerobically grown in a first-stage chemostat, and then pumped to a second-stage plug-flow reactor where anaerobic Cr(VI) reduction occurred. Experimental results demonstrated that near complete removal of Cr(VI) was achieved in the plug-flow reactor under appropriate operating conditions. The removal efficiency in the plug-flow reactor was significantly affected by the influent Cr(VI) concentration, Cr(VI) loading rate, liquid detention time, and a consumed Cr(VI) reduction capacity factor. The consumed Cr(VI) reduction capacity factor was directly related to the toxicity effect of Cr(VI) on cells. To illustrate the influence of the consumed reduction capacity factor on Cr(VI) reduction in the plug-flow reactor, a mathematical model was developed by incorporating Cr(VI) reduction kinetics into the mass balance relationship of Cr(VI) for a plug-flow reactor. Analyses of Cr(VI) concentration profiles along the plug-flow reactor using both model simulations and experimental data indicated that the rate of Cr(VI) reduction decreased with the depletion of the reduction capacity of cells and Cr(VI) reduction ceased after the reduction capacity was exhausted.

Original languageEnglish
Pages (from-to)798-804
Number of pages7
JournalJournal of Environmental Engineering (United States)
Issue number11
StatePublished - Nov 1995

ASJC Scopus subject areas

  • General Environmental Science
  • Environmental Engineering
  • Environmental Chemistry
  • Civil and Structural Engineering


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