(339h) Produced Water and Waste Heat-aided Blowdown Water Treatment: Using Chemical and Energy Synergisms for Value Creation

Cooling of high temperature steam at thermoelectric power plants requires large quantities of freshwater and generates a waste stream from the blowdown (BD) operation. This BD water can be treated and reused as make-up water for the cooling operation to reduce the freshwater demand. However, traditional treatment of BD is chemical- and energy-intensive and adds to the overall costs of water management for power plants. Taking advantage of the complementary chemistries of the BD water and produced water (PW) from shale gas production, this study evaluated the feasibility of a co-treatment process for both waters to reduce chemical and energy footprints of the water treatment while maximizing generation of useful streams include low-salinity water and concentrated brine as a saleable byproduct. The cotreatment process includes mixing of field-collected BD water and PW, chemical softening, activated carbon (AC) filtration, and reverse osmosis (RO) followed by thermal desalination. The results showed that a 10:1 mixing of BD and PW (i.e., BD/PW = 10) removed > 90 % of Ba. The softening using sodium carbonate removed > 95% scale forming divalent ions, and the AC filtration resulted in ~90% total organic carbon removal. Effluent from the softening and AC treatments was conducive to the RO treatment, which showed maximum water recovery and energy savings under 900 psi. Compared to BD and PW treated separately, the co-treatment process resulted in a ~50% chemical saving potential for softening. The RO treatment of the mixed 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. Overall, this co-treatment approach can dispose two prevalent waste streams from power and energy production, result in reduction in the treatment chemical and energy footprints as well as recovery of useful products from the wastes.