Remediation of hydrocarbon contaminants in cold environments : electrokinetically enhanced bioremediation and biodegradable oil sorbents
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Doctoral thesis (article-based)
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Date
2006-11-03
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Mcode
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Language
en
Pages
56, [64]
Series
Reports from the Department of Ecological and Environmental Sciences, University of Helsinki, 6
Abstract
Owing to the vast amounts of oil in the world, oil spills are common on land as well as at sea. In addition to oil products, other industrially used hydrocarbons, such as creosote, also contaminate soils. Most hydrocarbons are biodegradable. Hence, bioremediation is an attractive alternative for cleaning up hydrocarbon spills. In cold climate areas, however, biodegradation is often a slow process. The aim of this thesis was to develop efficient, cost-effective, and ecologically sound techniques for cold climate areas for the treatment of both oil spills on water or solid surfaces and for subsurface contamination. For subsurface hydrocarbon spills, the approach was to use electrokinetics in order to deliver nutrients and possibly microorganisms to contaminated soils, and in order to heat the soil to increase contaminant bioavailability and microbial activity. Electroosmosis proved to be an effective method to disperse bacteria and nutrients in medium- or fine-grained soils, where uncharged particles migrated with water through the soil towards the cathode. Creosote degradation proceeded faster with electroosmotically added nutrients than in controls without additions. However, inoculation with enriched creosote-degraders was not necessary because the indigenous microbes of the soil were well adapted to the creosote contaminants. For small-scale oil spills, the usual remediation method involves absorption with oil sorbents. Most sorbents in use today are synthetic and incineration is the only method for their disposal. A biodegradable sorbent, however, could be processed, for instance, in compost-like systems. Cotton grass is a common plant in peat bogs and its water-repellent fibre is a by-product of peat excavation. Cotton grass proved to be an excellent oil sorbent especially for spills on the surface of water: It absorbed up to three times as much oil as a commercial, synthetic oil sorbent. Cotton grass performed extremely well also in conditions simulating winter in the Baltic Sea. In addition, the effect of drying microbial suspension on an oil sorbent to enhance oil degradation of the oily sorbents was investigated. Microbial treatment of oil sorbents could be beneficial in mineral soils with low initial microbial density if fast degradation is of importance. Otherwise, it may not be worthwhile.Description
Keywords
oil spill, bioremediation, electrokinetics, creosote, oil sorbents, cotton grass, öljyvuodot, bioremediaatio, elektrokinetiikka, kreosootti, öljynimeytysaineet, tupasvilla
Other note
Parts
- Suni, S. and Romantschuk, M., 2004. Mobilisation of bacteria in soils by electro-osmosis. FEMS Microbiology Ecology, 49, 51-57.
- Suni, S., Malinen, E., Kosonen, J., Silvennoinen, H. and Romantschuk, M., 2007. Electrokinetically enhanced bioremediation of creosote-contaminated soil: laboratory and field studies. Journal of Environmental Science and Health, Part A, A42 (7), in press.
- Suni, S., Kosunen, A.-L., Hautala, M., Pasila, A. and Romantschuk, M., 2004. Use of a by-product of peat excavation, cotton grass fibre, as a sorbent for oil-spills. Marine Pollution Bulletin, 49, 916-921.
- Suni, S., Kosunen, A.-L. and Romantschuk, M., 2006. Microbially treated peat-cellulose fabric as a biodegradable oil-collection cloth. Journal of Environmental Science and Health, Part A, A41 (6), 999-1007.