Bioremediation of petroleum hydrocarbon contaminated soil using indigenous cultures

Ma, Zhongyun (1998) Bioremediation of petroleum hydrocarbon contaminated soil using indigenous cultures. Masters thesis, Memorial University of Newfoundland.

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Abstract

This research consisted of studying the biodegradation potential of Total Petroleum Hydrocarbons (TPH) in a diesel contaminated soil using indigenous cultures. From a site investigation conducted on a polluted site in Argentia (Newfoundland, Canada), typical soil profiles and contaminants were determined for helping in setting up an Environmental Test Facility. The potential for bioremediation of soils in that area was studied in the laboratory. Four lands of cultures were isolated from the petroleum hydrocarbon (diesel) contaminated soil, enriched in the laboratory and injected into the soil as a seed to increase the population of cultures. The contaminated soils were incubated in closed reactors at temperatures ranging from 25 to 5°C and pH values from 6 to 8. The addition of mineral salts as nutrients was also included. Surfactants were used as additional chemicals to enhance the rate of bioremediation. -- The degradation of TPH was evaluated by concentration monitoring (Gas Chromatography) and bacteria counting. Temperature effects study showed that biotreatability markedly decreased with decreasing temperature. The optimal rate of bioactivity was obtained in a neutral or slight acid condition, and surfactant Triton X-100 showed an enhancement of degradation of petroleum hydrocarbon, while the surfactant Tween 60 did not improve degradation. Nutrient requirement was also clearly identified. Under optimal condition, the TPH removal efficiency reached 50% of the initial value. It was also observed that bacteria seeding is possible and echances the remediation rate. -- Surfactants were used to wash diesel out of the contaminated soils in column tests. Distilled water, 0.5% (w/w) aqueous solution of surfactant Tween 60 and 0.5% (w/w) aqueous solution of surfactant Triton X-100 were used as leaching solutions. Corresponding TPH removals were obtained as 5.3%, 21.7%, and 67.8% respectively, demonstrating potential efficiency of combining physical and biological remediation methods.

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