Recently, the 200m3/h industrial wastewater zero discharge recycling project undertaken by Hangzhou Water Treatment Technology Development Center Co., Ltd. (HWC) in Baotou was officially accepted after 168-hour continuous and steady operation. The wastewater of the project mainly comes from multi-media filter backwash water, RO concentrated water, ion exchange recycled wastewater, RO chemical cleaning wastewater, circulated cooling wastewater, flue gas desulfurization wastewater, boiler chemical cleaning wastewater and chemical lab wastewater. The wastewater has high-content and complex inorganic salts such as calcium, magnesium and sulfate, therefore, direct evaporation and crystallization of wastewater not only consume a great deal of energy but also generates carnallite that is hard to be processed. HWC, according to the characteristics of water quality, pre-treats, desalts and concentrates the wastewater through organic combination of membrane processes, thereby reducing the evaporation capacity, ensuring that the crystallized salt meets the requirements on industrial salt, truly realizing zero discharge recycling of wastewater and effectively lowering the costs for investment in and operation of evaporation equipments. Since the wastewater has high content of mixed salt, the project team has specially designed and developed a set of combined-membrane zero discharge technologies. After being pre-treated by the ultra-filtration system, the wastewater is desalted via nano-filtration and then re-concentrated by the RO unit, so as to reduce the evaporation rate to 5 cubic meters per hour. The adoption of the technique for mechanical recompression of vapor also helps significantly reduce energy consumption of crystallization. The implementation of the project is expected to reduce RMB4.72 million water investment cost and RMB3.5 million of sewage charge.