Author(s): Payton Seats; Mohammad Ahmed; Golnoosh Khajouei; Hunter Barber; Harry Finklea; Fernando Lima; Lian-Shin Lin

Linked Author(s): Payton Seats, Fernando Lima, Lian-Shin Lin

Keywords: Blowdown water reuse; Produced water; Co-treatment; Resource recovery; Water treatment footprints; Multi-objective planning

Abstract: Freshwater use for cooling operation at thermoelectric power plants generates large quantities of wastewater from blowdown (BD) in the cooling system. Treatment of this BD water to remove scale-forming constituents and recover the water for reuse can reduce freshwater demand for power generation. Due to its complementary chemistry and often proximity in energy producing regions, produced water (PW) from natural gas production can potentially be introduced into BD water treatment to create chemical and energy synergisms for treating the waters. This study evaluated the feasibility of a pilot-scale co-treatment process for both waters to maximize recovery of water for reuse and useful materials (barite and concentrated brine) as saleable byproducts. The cotreatment process includes mixing of field-collected BD water and PW, chemical softening, activated carbon filtration, and reverse osmosis (RO) followed by thermal desalination. The study showed properly mixing ratio of the two waters (e.g., BD:PW = 10:1) resulted in >90% barium removal, and softening of the mixture water with sodium carbonate removed >95% of all scale-forming divalent ions. Compared to treating BD and PW separately, the co-treatment process resulted in a ~50% chemical saving potential for softening. The RO treatment of the mixture water had an energy consumption 0.05 kWh per liter of the RO permeate, and resulted in overall energy saving for producing 10-lb brine. A process simulation model was developed to evaluate the treatment train’s performance and economics at the plant-scale. Specialized electrolyte thermodynamic and custom water treatment models were employed and validated with experimental and literature results to justify process design decisions. Techno-economic analysis and sustainability assessment of the simulated process for improved water reuse, lower chemical and energy footprints, and generation of useful products were carried out. A multi-objective planning methodology was developed to evaluate the benefits of applying the co-treatment approach for managing BD water and PW in an energy producing region. The method uses geocoded data of power plants and gas production wells, water quantities and chemistries, chemical and energy footprints of treatment units in calculating the costs of transporting waters and treatment, and quantities of recovered useful products.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221630

Year: 2022