Degradation Potential and Growth of Anaerobic Bacteria in Produced Water

The efficiency of an anaerobic biological treatment for the reduction of essential contaminants of produced water from an offshore oilfield was investigated using a microbial consortium enriched with sulphate-reducing bacteria (SRB). Experiments were conducted in a bench bioreactor at 35 degrees C, 250 rpm, with intermittent purges of N2 gas in order to establish anaerobic conditions and to remove the H2S generated. The results showed that pH control effectively influenced the activity of the anaerobic bacteria leading to COD removal of 57%. Meanwhile, pH control was found to have no influence on the removal efficiencies of oil and grease and total phenols. In all experiments, removals of oil and grease and total phenols of 60% and 58-67%, respectively, were obtained after a 15-day process. In studies carried out with biomass reuse the reductions obtained were 61% for oil and grease and 78% for total phenols over the same period. Such results point to the technical feasibility of anaerobic biodegradation for oilfield wastewater treatment.