A comparative analysis of the physico-chemical parameters of treated oilfield formation water and that of a freshwater stream with no previous history of pollution from oil exploration activities was determined. The environmental impact resulting from the discharge of treated oilfield formation water into freshwater samples collected from this stream with no previous history of pollution from oil exploration activities was assessed in terms of changes in water quality parameters such as Dissolved oxygen (DO), Biochemical oxygen Demand (BOD) and in the microbial populations of the freshwater samples over a period of seven days since oilfield formation water readily mixes with flowing water after discharge. The analyses showed that concentrations of constituents such as chloride, total dissolved solids, total hardness, nitrate nitrogen and ammonium nitrogen alkalinity and silicate of the oilfield formation water were much higher than those of the freshwater source. The oxygen uptake (BOD values) in some stations of the freshwater stream differed significantly only at the 5% level after the treatment. Generally, the microbial populations were also lower after the treatment. Such observations suggest that, there is reduction in the biological activities of the freshwater after the addition of the treated oilfield formation water.
(Journal of Applied Sciences & Environmental Management: 2003 7(1): 61-65)