THE EFFECT OF OXYGEN ON PERCHLORATE
REDUCTION IN A BIOFILM REACTOR |
Hyeoksun Choi† |
School of Environmental Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, 790-784, Korea |
Corresponding Author:
Hyeoksun Choi ,Tel: +82-54-279-8358, Fax: +82-54-279-8299, Email: hyeoksun@postech.ac.kr |
Received: July 9, 2007; Accepted: September 8, 2007. |
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ABSTRACT |
The purpose of this research was to investigate the effects of low concentration of oxygen on
reduction of perchlorate, especially low perchlorate influent concentrations in a biofilm reactor, as well as
the effect of flow pattern in a biofilm reactor. Dissolved oxygen averaging 1 mg/L did not inhibit reduction
of influent perchlorate from 23 to 426 μg/L in the biofilm reactors when sufficient acetate was added,
probably due to limitation of oxygen diffusion into the biofilm. Influent perchlorate ranging from 23 to 426
μg/L was reduced to below detection level (4 μg/L) in the presence of 1 mg/L dissolved oxygen (DO).
Chloride was produced in a ratio of 0.37gCl-/gClO4
- and 0.35gCl-/gClO4
- in plug flow and recirculation
biofilm reactor which is similar to stoichiometric amount (0.36gCl-/gClO4
-) indicating complete perchlorate
reduction at 426 μg/L of ClO4
- feeding. At 23 μg/L influent perchlorate, total biomass solids were 3.18 g
and 2.81 g in the plug flow and recirculation biofilm reactors. The most probable number (MPN) analysis
for perchlorate-reducing bacteria showed 104 to 105 cells/cm2 in both biofilm reactors throughout the experiments.
The effluent perchlorate concentrations were not significantly different in the two different flow
regimes, plug flow and recirculation biofilm reactors. |
Keywords:
Biofilm reactor | Oxygen | Perchlorate |
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