Intensification of oil destruction processes in sediments by aeration

The remediation of oil-contaminated environment is a topical problem on the worldwide scale chained from productionto transport of oil and oil refinery products. The experimental work is aimed at studying the rate of oil destruction in sediments andthe intensification of these processes by enforced aeration and bioturbation. The common species of tubificid worms Limnodrilus hoffmeisteri(Claparede, 1862) was used in the lab experiment. Dissolved oxygen content in the air pumped aquariums was more than7 mg/l. The maximum was observed in aquariums without worms - 7.31  0.05 mg/l and oxygen content was slightly lower in thosewith worms 7.08  0.03 mg/l. Lower concentrations were determined in aquariums without aeration: 4.75  0.10 mg/l without worms;3.06  0.02 mg/l with worms. Samples of sediments were analyzed on oil hydrocarbons content in the end of the experiment. The analysisresults indicated the differences on residual oil content between aquariums under different experimental conditions. Highest residualoil concentration of 14.2  0.2 g/kg was observed in non aerated aquariums without worms. Oil content in sediments decreased by 2.6%after three months. The low rate of self-restoration capacity was observed in air pumped aquariums without worms, too. The average oilconcentration in the end of the experiment was 13.95  0.65 g/kg and that is equal to a decrease by 4.3% in comparison with the initialsubstrate. A relatively high concentration of dissolved oxygen did not affect the complexes of self-restoration processes in the testedaquariums. Oil reduction in sediments was more significant in aquariums with worms but under oxygen deficient conditions (withoutpumping) - 12.9  0.3 g/kg (reduction rate - 11.5 %). Most optimal conditions for remediation processes were gained in aquariumswith worms and with 24-hour water aeration. The residual oil content was 10.05  0.05 g/kg (reduction rate - 69%) in the end of theexperiment. Sufficient dissolved oxygen content and bioturbation along with optimal temperature conditions are the main factors acceleratingremediation processes in oil-contaminated sediments.

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