Identification and Characterization of Aromatic Degrading Halomonas in Hypersaline Produced Water and COD Reduction by Bioremediation by the Indigenous Microbial Population Using Nutrient Addition

Abstract

Hypersaline produced water is a high volume waste stream that is typically contaminated by toxic low molecular weight aromatic compounds exemplified by phenol. Aromatic compound degrading Halomonas were isolated from hypersaline produced water obtained from offshore operations in Brazil, which had a chemical oxygen demand (COD) of 4300 mg/L. These isolates were able to aerobically degrade the oxygenated aromatics phenol, benzoic acid, para-hydroxybenzoic acid and some isolates were shown to produce aromatic dioxygenase activities associated with highly conserved aromatic degradation pathways utilized by a broad range of aromatic degrading bacteria. The presence of aromatic degrading bacteria in the hypersaline produced water suggested that the COD content could be reduced by bioremediation using the indigenous microbial population by the addition of nutrients. Using this approach a variety of nitrogen, phosphorous and carbons sources were identified that individually or in combination significantly improved the reduction in COD after aerobic incubation. These results demonstrate the potential of applying bioremediation to undiluted hypersaline produced water for COD reduction and aromatic compound removal.