TREATMENT OF HIGH-SALT WASTEWATER FROM COAL-FIRED THERMAL POWER PLANTS

This paper described an optimal zero-emission process for high-salt wastewater. Through redesign of the post-treatment process of the conventional wastewater zero-emission process, with the aim of optimizing the method and maximizing the economic benefits, various methods of the important steps in the process were demonstrated and screened, and the actual process was established as chemical softening-tube microfiltration-nanofiltration-reverse osmosis (RO)-dish-tube reverse osmosis (DTRO). The combined route of the evaporative crystallization system (for salt nitrate production) was applied to recover Na₂SO₄ and NaCl sequentially. Multiple detection methods was used on the generated NaCl through crystallization, and the quality of sodium chloride product was proved to reach the superior grade of Industrial Salt (GB/T 5462—2015), and the external sales were realized. Zero pollution and discharge were truly achieved by the total recycling of wastewater.