Physical characterization and microbiological settling-rate modification of aqueous suspensions from hot-water-process oil-sands extraction
✍ Scribed by Martin B. Hocking
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 753 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0016-2361
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✦ Synopsis
Sealed samples of specific aqueous hot-water-process-tar-sands-extraction streams and tailings pond sludges have been examined microbiologically and shown to contain compatible micro-organisms. Portions of these have been treated aerobically and anaerobically, with and without added nutrient, to encourage hydrocarbon utilization, and the results compared with experiments conducted with untreated and boiled control samples. While both aerobes and anaerobes appear to be indigenous in the matrices examined, aerobic treatment with nutrient present was found to give optimum solids-settling performance, and anaerobic treatment negligible short-term settling effect, although a slight improvement was noted for longer-term tests, Extraction of bitumen from bituminous sands by the hotwater process efficiently recovers the bulk of the petroleum fraction and returns most of the larger-grained mineral matter in readily dewatered form. However, as currently practised, a significant proportion of the extraction water cannot be recycled because of build-up of a stable suspension of mineral fines together with bitumen'. This stable suspension not only contributes to a larger fresh water requirement for process operation but, probably of greater concern, results in a gross tailings volume larger than the capacity of minedout areas.
The technological solutions which have been tested have been summarized previously2. None have been adopted, either because they were found to be poorly effective or too costly. Also a number of chemical approaches to improving solids separation characteristics have been examined experimentally, some of which appear to have promise2. While one genus of bacterium, Nocar&, has been artificially irmoculated into a tar-sands tailings suspension and the degree of bitumen degradation noted there has been no published work relating to the effect of less specific microbiological treatment.
Since Haas, many years ago, noted that oil-inundated soil was the best source for hydrocarbonoxidizing micro-organisms4, it was thought that the bituminous-sand deposits themselves may be the best source of organisms for degrading bitumen, supported by reports of the finding of oxidized hydrocarbon fragments2$'. Furthermore, Parkinson has experimentally noted that many oil-degrading bacteria are only able to utilize selectively particular hydrocarbon substrates, whereas all oil-degrading fungi are capable of utilizing the whole range of straightchain paraffms6. This suggested that for maximum hydrocarbon degradation rate and completeness, significant advantage could be gained by utilization of co-metabolism by both kinds of micro-organisms.
Considerations such as these, together with the knowledge that micro-organisms utilizing crude oil thrive under high-moisture conditions',