| Oil and gas production has generated substantial volumes of wastewater over the past decade. Due to high salinity, which can exceed 100,000 mg/L, and the presence of organic and inorganic constituents, considerable challenges must be overcome to effectively treat O&G wastewaters for beneficial reuse (e.g., irrigation, livestock watering, industrial water, surface water recharge). Currently nearly 90% of wastewater produced during the life of an oil well is disposed of through deep-well injection. Produced water brought to the surface during the production process contains formation water of highly variable composition that was previously trapped in the rock. This wastewater contains high dissolved organic matter and salt concentrations, as well as various inorganic compounds. Advanced treatment technologies must be developed to remove this broad range of contaminants from O&G waste streams to maximize options for water reuse.;This study investigates the potential for publically owned treatment works using biological treatment processes to adequately co-treat produced water and municipal wastewater. This study utilized a pilot-scale sequencing batch reactor-membrane bioreactor (SBR-MBR) hybrid treatment system to remove organic compounds, primary nutrients, and suspended solids from a mixture of municipal and O&G wastewaters for beneficial reuse. The fate of dissolved organic compounds and metals of concern throughout the treatment train, how to optimize sodium chloride loading rates to achieve effluent goals, and the change in characteristics of the adapting biological community are addressed.;Produced water was initially dosed at 6% by volume, and the SBR-MBR system achieved comparable removal of primary (i.e., chemical oxygen demand, ammonia) and secondary constituents (i.e., trace organic compounds, inorganic contaminants) to control conditions. When produced water was increased to 20% of the influent by volume, nitrification was lost, indicating the threshold at which removal is effected by produced water dose lies between 6% and 20% by volume. Over this time, the biological community in the bioreactors remained stable providing evidence of a robust system. |
