Bioremediation of Oil-Contaminated Fine Sediments

Bioremediation of oil contamination has been shown to be effective for cobble and sandy shorelines. To assess the operational limitations of this technology, this project studied its potential to treat buried oil in fine sediments. The effectiveness of bioremediation by nutrient enrichment with water-soluble mineral fertilizers was quantified experimentally with a randomised block design with three replicate blocks. Each block consisted of an untreated control plot, a plot treated with fertilizer alone, an oiled plot, and an oiled plot treated with fertilizer. The sediment in each plot was retained in mesh enclosures and buried at a depth of 0.15 m. Weathered and emulsified Arabian Light crude oil was applied to the appropriate plots at 3.7 kg.m−−2. Bioremediation success was monitored by examining in situ CO2 production rates; changes in residual hydrocarbons normalized to 17?(H), 21?H)-hopane; and response of hydrocarbon-degrading microorganisms. Fertilizer treatments significantly increased the biodegradation of petroleum hydrocarbons (p = 0.0001) in the buried sediments. These conclusions were supported by in situ CO2 production data. Microbiological analyses showed that nutrient addition increased the numbers of hydrocarbon-degraders on the oiled plots tenfold. The results clearly showed that bioremediation can treat oil buried in fine sediment following a spill incident.