TY - JOUR
T1 - Microbial ecology of a perchlorate-reducing, hydrogen-based membrane biofilm reactor
AU - Nerenberg, Robert
AU - Kawagoshi, Yasunori
AU - Rittmann, Bruce
N1 - Funding Information:
The authors gratefully acknowledge the AWWA Research Foundation (AwwaRF) for managing this study (Project no. 2530). Funding was provided by the Environmental Protection Agency, via a Congressional earmark to the East Valley Water District. We also acknowledge our partners in this study, Samer Adham, Tom Gillogly, and Geno Lehman of Montgomery Watson Harza, Inc.
PY - 2008/2
Y1 - 2008/2
N2 - The hydrogen-based membrane biofilm reactor (MBfR) has been shown to reduce perchlorate to below 4 μg/L, but little is known about the microbial ecology of this or other hydrogen-based reactors, especially when influent perchlorate concentrations are much lower than the influent oxygen and nitrate concentrations. Dissimilatory (per)chlorate-reducing bacteria (PCRB) can use oxygen as an electron acceptor, and most can also use nitrate. Since oxygen and nitrate can be reduced concurrently with perchlorate, they may serve as primary electron acceptors, sustaining PCRB when the perchlorate concentrations are very low. We studied five identical MBfRs, all seeded with the same inoculum and initially supplied with oxygen, or oxygen plus nitrate, in the influent. After 20 days, perchlorate was added to four MBfRs at influent concentrations of 100-10,000 μg/L, while the fifth was maintained as a control. One day after perchlorate addition, the MBfRs displayed limited perchlorate reduction, suggesting a low initial abundance of PCRB. However, perchlorate reduction improved significantly over time, and denaturing gradient gel electrophoresis (DGGE) analyses suggested an increasing abundance of a single Dechloromonas species. Fluorescence in-situ hybridization (FISH) tests showed that the Dechloromonas species accounted for 14% of the bacterial count in the control MBfR, and 22%, 31%, and 49% in the MBfRs receiving nitrate plus 100, 1000, and 10,000 μg/L perchlorate, respectively. The abundance was 34% in the MBfR receiving oxygen plus 1000 μg/L perchlorate. These results suggest that oxygen is more favorable than nitrate as a primary electron acceptor for PCRB, that PCRB are present at low levels even without perchlorate, and that the presence of perchlorate, even at low levels relative to nitrate or oxygen, significantly enhances selection for PCRB.
AB - The hydrogen-based membrane biofilm reactor (MBfR) has been shown to reduce perchlorate to below 4 μg/L, but little is known about the microbial ecology of this or other hydrogen-based reactors, especially when influent perchlorate concentrations are much lower than the influent oxygen and nitrate concentrations. Dissimilatory (per)chlorate-reducing bacteria (PCRB) can use oxygen as an electron acceptor, and most can also use nitrate. Since oxygen and nitrate can be reduced concurrently with perchlorate, they may serve as primary electron acceptors, sustaining PCRB when the perchlorate concentrations are very low. We studied five identical MBfRs, all seeded with the same inoculum and initially supplied with oxygen, or oxygen plus nitrate, in the influent. After 20 days, perchlorate was added to four MBfRs at influent concentrations of 100-10,000 μg/L, while the fifth was maintained as a control. One day after perchlorate addition, the MBfRs displayed limited perchlorate reduction, suggesting a low initial abundance of PCRB. However, perchlorate reduction improved significantly over time, and denaturing gradient gel electrophoresis (DGGE) analyses suggested an increasing abundance of a single Dechloromonas species. Fluorescence in-situ hybridization (FISH) tests showed that the Dechloromonas species accounted for 14% of the bacterial count in the control MBfR, and 22%, 31%, and 49% in the MBfRs receiving nitrate plus 100, 1000, and 10,000 μg/L perchlorate, respectively. The abundance was 34% in the MBfR receiving oxygen plus 1000 μg/L perchlorate. These results suggest that oxygen is more favorable than nitrate as a primary electron acceptor for PCRB, that PCRB are present at low levels even without perchlorate, and that the presence of perchlorate, even at low levels relative to nitrate or oxygen, significantly enhances selection for PCRB.
KW - Hydrogen
KW - Membrane biofilm reactor
KW - Microbial ecology
KW - Perchlorate
KW - Secondary substrate
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U2 - 10.1016/j.watres.2007.08.033
DO - 10.1016/j.watres.2007.08.033
M3 - Article
C2 - 17915282
AN - SCOPUS:38949099332
SN - 0043-1354
VL - 42
SP - 1151
EP - 1159
JO - Water Research
JF - Water Research
IS - 4-5
ER -