| The development of hydrocarbon resources such as crude oil, coalbed methane, conventional gas, and tight-shale gas unvaryingly results in the generation of brackish wastewaters. Brackish wastewater is characterized by salt content, often expressed as total dissolved solids (TDS). In the United States, over 21 billion barrels of produced water are generated every year. The disposal of this produced water has major economic and environmental implications. Current reverse osmosis (RO) treatment methods yield clean water recovery rates ranging from 50-75%, commonly limited by fouling by mineral scalants such as CaCO3 and CaSO4. Low recovery rates result in large concentrate or waste stream that is more difficult to dispose of than the original produced water.;To address the low recoveries caused by mineral fouling in RO systems, we have developed an integrated system that treats the primary RO concentrate via Accelerated Precipitation Softening (APS) and microfiltration (MF) before passing the water to a secondary RO treatment. The combined APS-MF system removes scalants as precipitates resulting in a superior feed water to the secondary RO with significantly reduced calcium concentration. The combined process provides a feasible pathway for beneficial reuse of produced water, such as irrigation of crops. |
