Novel Co-treatment of Cooling Blowdown Water and Produced Water: A Regional Approach for Resource Recovery and Treatment Footprint Reduction

Taking advantage of the complementary chemistries of the cooling blowdown water (BDW) and produced water (PW) from shale gas production, this pilot study evaluated their co-treatment feasibility to generate useful products while reducing treatment footprints. The process includes the mixing of BDW and PW, chemical softening, activated carbon (AC) filtration, and reverse osmosis (RO). The results showed that a simple mixing of BDW and PW (BDW/PW = 5) readily removed 98% of barium and 85% of sulfate and generated a high-density (4.1 g/cm3) barite-dominant solid with a yield of 1.92 kg/m3 mixed water. Softening using sodium carbonate and sodium hydroxide removed >95% scale forming divalent ions, and the AC filtration resulted in ∼90% total organic carbon removal. RO treatment of the AC effluent achieved ∼60% water recovery. Compared to BDW and PW treated separately, the co-treatment process resulted in a ∼70% chemical saving. The RO concentrate had high enough TDS (77 g/L) suitable for thermal evaporation to generate commercial-grade 10-lb brine. An initial technoeconomic analysis of a co-treatment scenario using a thermoelectric powerplant in West Virginia shows cost saving potential and revenue generation. This study demonstrates the potential of the co-treatment method as a useful tool for sustainable regional water management.