Abstract

Microbiological and Physicochemical survey was undertaken in produced water and its receiving environment with the aim of verifying the likely impacts of produced water constituents on the immediate receiving marine near shore shallow environment. The sampling was carried out in two seasons, late wet season and late dry season. The results obtained indicate that the chemical constituents of the discharged produce water are capable of sustaining microbial growth and proliferation. Produce water from Escravos tank farm had relatively moderate concentrations of hydrocarbon utilizing microorganisms and sulphate reducing bacteria and the concentration of these organisms were much higher at the point of discharge of the produced water. Physicochemical analysis showed that Produce water had lower salinity and sulphate levels than the receiving marine water but the reverse was the case with the BOD, COD and Hydrocarbon constituents. The two seasons under investigation showed similar results. From the analytical data, it can be advanced that the impacts of produced water microbial flora on the receiving environment is limited to the vicinity of the discharge point of about 100 m in diameter and also to some extent up to a distance of 500 m upstream along the direction of flow of produced water discharges. It is expected that while the hydrocarbon degrading microorganisms plays a beneficial role of degrading and detoxifying abundant produced water hydrocarbons in the sediment and the surface water, Sulphate reducing bacteria might at the same time be playing a detrimental role of oxidizing certain organic compounds or hydrogen and reducing sulphate and other reduced sulphur compounds in the marine water and sediment  to hydrogen sulphide which can be very toxic to bacteria, aquatic animals and man.

Key words: Produced water, sulphate reducing bacteria, hydrocarbon utilizing bacteria.