Ultrastructure of a bio-electrolytic methanogenic/methanotrophic granular biofilm for the complete degradation of tetrachloroethylene in contaminated groundwater.
The electrolytical methanogenic/methanotrophic coupling (eMaMoC) process was tested in a laboratory-scale single-stage reactor for the treatment of tetrachloroethene (PCE)-contaminated waters. A water electrolysis cell was placed directly in the effluent recirculation loop for the supply of both O2 and H2 to the system: H2 serving as the electron donor for both carbonate reduction into CH4 and reductive dechlorination. The concurrent presence of O2 and CH4 could be used by the methanotrophs for co-metabolically oxidising the chlorinated intermediates left over by the anaerobic transformation of PCE. At a PCE inlet of 33-52 microM and a hydraulic residence time (HRT) of 5.6 days, PCE reductive dechlorination to dichloroethene (DCE) was over 95% with a maximum DCE mineralisation of 83%. Fluorescence in situ hybridisation with 16S rRNA probes related to type I and type II methanotrophic bacteria were utilised to localise the methanotrophic communities in the anaerobic/aerobic granules. It evidenced that with operational time, along with increasing oxygenation rate, methanotrophic communities were specifically colonising onto the outermost layer of the anaerobic/aerobic granule.
Guiot
S R
SR
Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount, Montreal, Canada, H4P 2R2. serge.guiot@cnrc-nrc.gc.ca
Kuhn
R
R
Lévesque
M J
MJ
Cimpoia
R
R
D001420:Bacteria, Aerobic / Q000235:genetics / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D019149:Bioreactors; D004269:DNA, Bacterial / Q000235:genetics; D004000:Dichloroethylenes / Q000378:metabolism; D004572:Electrolysis; D017404:In Situ Hybridization, Fluorescence; D008697:Methane / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013750:Tetrachloroethylene / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014881:Water Supply
D004269:DNA, Bacterial; D004000:Dichloroethylenes; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D008697:Methane; D013750:Tetrachloroethylene