Interactions between nitrifying bacteria and hydrocarbon-degrading bacteria during detoxification of oil sands process affected water
- Microbial Technologies, Vancouver, British Columbia (Canada)
- Syncrude Research, Edmonton, Alberta (Canada)
Large quantities of process water are produced during the extraction of bitumen from oil sands by the Syncrude and Suncor operations in northern Alberta. Freshly produced tailings water is acutely toxic, but it has been shown to slowly detoxify over time. As detoxification proceeds, there is also a precipitous decrease in ammonia concentrations. The present study examines these two microbially-mediated processes in relation to levels of bacteria and toxicants in mixtures of fresh and aged (detoxified) tailings water. Detoxification of tailings water was greatly accelerated when equal volumes of fresh and detoxified (natural aging for one year) tailings water were mixed. Addition of phosphorus further stimulated detoxification, causing levels of ammonia and naphthenic acids (toxic organic acids leached during bitumen extraction) to decrease to those of detoxified water within two months. Such changes were not observed when phosphorus was not added, or when it was added to less diluted (10-.1 or 3-.1) fresh tailings water. Populations of nitrifying bacteria and naphthenic acid degraders increased markedly in the phosphorus-amended mixtures, but not in its absence. Addition of CS{sub 2} (a specific inhibitor of nitrification) to these mixtures prevented ammonia oxidation. Surprisingly, it also prevented the increase in naphthenic acid-degraders and retarded the loss of naphthenic acids. These results suggest the existence of interactions in fresh tailings water between nitrifying bacteria, naphthenic acid degraders and toxicants. The activity of naphthenic acid-degraders apparently remains low until ammonia is oxidized, whereas that of nitrifying bacteria remains low until concentrations of naphthenic acids or other toxicants decrease below some threshold level. Understanding these interactions may lead to more efficient and effective processes to detoxify oil sands process water.
- OSTI ID:
- 242339
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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