Zhong’an United’s zero-discharge technology for high-salt wastewater has passed technical evaluation

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Zhong’an United’s zero-discharge technology for high-salinity wastewater passed technical evaluation. According to Zhong’an Coal Chemical, between November 19 and 20, 2020, after two days of technical assessment, the project titled “Research on Zero-Discharge Treatment Technology for High-Salinity Wastewater in Zhong’an United Coal Chemical” was approved by the expert panel. The expert group believes that the comprehensive zero-discharge technology for high-salt wastewater in Zhong’an United Coal Chemical Industry features high recovery rates, low energy consumption, as well as integration and modularity. It provides a solution for zero-discharge of high-salt wastewater in the coal chemical industry, with its overall technology reaching international leading levels. The research project on zero-discharge treatment technology for high-salt wastewater in Zhongan United Coal Chemical is a collaborative scientific effort involving units such as Great Wall Energy Chemical, Zhongan United, Engineering Construction Company, Beijing Research Institute of Chemical Technology, and Dalian Petrochemical Research Institute. It is one of Sinopec’s “Ten Dragon” scientific research projects. The research and development task has been completed, resulting in a complete set of technologies for zero discharge of high-salt wastewater, namely \"pre-treatment – reverse osmosis concentration – nanofiltration pre-treatment – nanofiltration salt separation and concentration – thermal separation and crystallization\". Zhongan Coal Chemical uses a series of physical and biochemical treatment processes, with most of the water being reused directly as make-up water for the circulating water system. A small amount of high-salinity water is pre-treated using the high-efficiency zero-discharge pretreatment, softening, and silicon removal technology developed by Beijing Zhonghuan Membrane Materials Technology Co., Ltd. This process effectively removes hardness, silicon, and fluoride from the water. Subsequent membrane concentration, nanofiltration for preliminary separation, evaporation, and crystallization are used to recover most of the water; at the same time, sodium chloride and sodium sulfate are obtained. A small amount of mother liquor is dried to produce miscellaneous salts, which are then transported away. The facility was put into operation in December 2019, and is designed to treat 360 tons of high-salinity wastewater per hour. After nearly a year of operation, the unit is running stably. In September 2020, the high-salt wastewater treatment unit at Zhongan Coal Chemical passed the performance calibration, with its key operational technical parameters exceeding the design values.