HR: 0800h
AN: B41C-04    [Abstracts]
TI: Anammox Coupled With Nitrification Impacts a Saline, High Ammonia Groundwater
AU: * Figueroa, L A
EM: lfiguero@mines.edu
AF: Colorado School of Mines Environmental Science & Engineering, 1500 Illinois St, Golden, CO 80401, United States
AU: Landkamer, L
EM: llandkam@mines.edu
AF: Colorado School of Mines Environmental Science & Engineering, 1500 Illinois St, Golden, CO 80401, United States
AU: Peterson, D M
EM: dpeterson@gjo.doe.gov
AF: S.M. Stoller Corp., 2597 Bū Road, Grand Junction, CO 81503, United States
AU: Metzler, D
EM: Donald.Metzler@gjo.doe.gov
AF: U.S. Department of Energy EnvironmentalManagement, 2597 Bū Road, Grand Junction, CO 81503, United States
AB: High amounts of ammonia (130 to 2200 mg-N/l) in a saline environment (TDS = 10-20 g/l) are present in a groundwater plume adjacent to the Colorado River near Moab, Utah. Ammonia levels sufficient to affect aquatic life have been observed in limited sections of the river adjacent to the site, which has prompted interim treatment efforts. Microcosm studies were performed to assess the potential for microbial transformations of ammonia in the hyporheic zone sediment and the effect of ground/river-water mixing on transformations. Experiments were conducted using sub-riverbed sediment and mixtures of groundwater (290 mg-N/L ammonia) and river water (100%, 50% and 10% plume water) in anaerobic and aerobic environments. Aqueous NH4+, NO2-, NO3-, pH, dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were monitored over 38 days. Interestingly, the ammonia concentration decreased in all microcosms (29% to 100%) with the highest removal occurring in the oxic microcosms. Total nitrogen removal ranged from 27% to 83%. Three lines of evidence suggest that anammox occurred in the anaerobic microcosms: 1) NH4+ concentrations decreased, 2) little change in DOC occurred and 3) DIC decreased. DIC should increase if denitrification were the dominant process. It is possible that small amounts of O2 diffused into the microcosms, driving some nitrification that supplied NO2- for anammox. In the aerobic microcosms, denitrification or anammox occurred in addition to nitrification because nitrate did not accumulate in general. Again, we believe anammox occurred because of DOC and DIC trends. In the aerobic 10% groundwater microcosm, NO3- accumulated once the ammonia concentration became low and the nitrate level stabilized after the ammonia was gone. This also indicated that anammox was the dominant process because denitrification should not stop due to ammonia depletion. The aerobic microcosms were only agitated twice per week, which would allow the sediments to become anoxic. Concurrent nitrification and anammox has been observed in aerobic wastewater treatment and sediment environments due to anaerobic microenvironments.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0432 Contaminant and organic biogeochemistry (0792)
DE: 0448 Geomicrobiology
SC: Biogeosciences [B]
MN: 2007 Joint Assembly