Application of the RESALT Technology in the FGD Wastewater Concentration Processing of Coal-Fired Power Plant

RESALT technology which is developed based on the Electric dialysis (ED) technology can effectively separate calcium ions from sulfate ions such that the scaling of CaSO₄ is inhibited while the wastewater condensation process can be accomplished at the same time. The experiments were conducted in Huadian Laizhou power company with the inlet flow of the FGD wastewater about 3-4 m³/h. The RESALT equipments were tested to treat three kinds of flue gas desulfurization (FGD) wastewater. The results show that sulfate ions could be efficiently separated from calcium ions and the high salt contained wastewater could also be concentrated at the same time. Since there is no additional chemical agents required for the wastewater pre-treatment, electricity consumption is the main component of the cost during the wastewater treatment process, which will rise as the salt concentration of the wastewater goes up. For example, with the concentrations of 6 480 mg/L of SO₄^2–, 1 820 mg/L of Ca²⁺, 2 462 mg/L of Mg²⁺, 20 680 mg/L of Cl^– and 10 465 mg/L of Na⁺ in the FGD wastewater, the overall electricity consumption rate is 49.5 kW·h per ton and the direct treatment cost is about 22.6 RMB/ton.