Demonstration and evaluation of potential configuration options for shale-wastewater treatment plant by combining several unit processes

The process of shale resource exploitation causes water-related problems, and it threatens the environment and is directly connected to sustainability of the industry. As a solution, several options for treatment plant configuration of shale produced water were investigated to determine the fit-for-purpose organization. The candidate processes are coagulation-flocculation (C–F), dissolved air flotation (DAF), ozonation (OZ), ion-exchange (IX), ultrafiltration (UF), and reverse-osmosis (RO). For all processes, their impacts on the features of the shale wastewater treatment were determined. The removal of oil and grease is critical for smooth operation, and could be achieved by adopting DAF→(OZ or UF). Treatment configuration options were designed to accommodate two situations: in-site reuse and discharge-to-nature. The performance of 17 configuration options was determined and each was recommended for use as in-site reuse or discharge-to-nature applications. Generally, C–F→DAF→OZ→IX is recommended for in-site reuse, and C–F→DAF→OZ→UF→RO is more suitable for discharge-to-nature. Total operating and maintenance cost of discharge plant is 2.425 times more expensive than that of in-site reuse. No studies have been published to date regarding plant design with these comprehensive technologies. Therefore, this study could provide fundamental information based on experimental results and a methodology for designing treatment plant configuration to realize sustainable shale production.