en.Wedoany.com Reported - The coal-fired power plant wastewater zero-discharge technology research and engineering demonstration project at Sanhe Power Plant, contracted by North China Power Engineering Co., Ltd. of China Energy Engineering Group, has completed overall commissioning, with all indicators meeting or exceeding design standards, laying the foundation for sustainable operation and deep environmental transformation of the power plant.
The project faced high requirements and technical challenges from the outset. It achieved, for the first time, the simultaneous recovery and resource utilization of two types of salts—industrial-grade refined sodium chloride and magnesium sulfate heptahydrate—integrating and applying multiple advanced and mature wastewater treatment technologies. The engineering technical route covers key stages including pretreatment, salt separation and concentration, and evaporation crystallization.
In the refined pretreatment system, targeting specific pollutants in the wastewater and the requirements of subsequent treatment systems, a selective pretreatment method of calcium removal with magnesium retention, and fluoride and silicon removal was adopted. This created stable influent conditions for subsequent deep treatment units and reduced the chemical treatment cost per ton of water to 40% of that in conventional zero-discharge projects.
In terms of high-efficiency membrane concentration technology, a combination of multi-stage nanofiltration and reverse osmosis was employed to perform multi-stage salt separation and concentration of the pretreated wastewater. The volume reduction was significant, recovering over 70% of high-quality freshwater for reuse in the production process, achieving internal water resource recycling and creating key conditions for the resource utilization of sodium chloride and magnesium sulfate heptahydrate.
In the precise evaporation crystallization process, mechanical vapor recompression and freeze crystallization technologies were applied to the high-salinity brine after salt separation and concentration. By controlling temperature, concentration, and pressure, high-purity salts were precipitated, and the condensed water was reused, achieving the resource separation, recovery, and zero discharge of dissolved solids in the wastewater.
This commissioning covered the entire process from wastewater collection to evaporation crystallization. The results showed that all system units operated stably and smoothly, with produced water quality exceeding reuse standards, good quality of crystallized salts, and key indicators such as system recovery rate and energy consumption meeting expectations. Overall system performance met standards, and operation was reliable and efficient, marking that the zero-discharge system is ready for formal operation.
This outcome validated the technical expertise of North China Power Engineering Co., Ltd. in system design and construction, providing reliable assurance for the power plant to achieve long-term stable wastewater zero discharge. The project pioneered the separation, purification, and resource utilization of sodium chloride and magnesium sulfate heptahydrate from high-salinity wastewater in thermal power plants, achieving zero discharge of wastewater from wet-cooling unit power plants and providing a technical reference for the industry.
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