**Domestically leading in wastewater recycling technology

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**China’s Leading Technology in Wastewater Recycling Author/Source: Sinochem News Network Date: October 15, 2020 Clicks: 26 On September 25, the China Nitrogen Fertilizer Industry Association organized experts to hold a project evaluation meeting in Meishan City, Sichuan, to assess the technological achievements of the integrated membrane filtration system for the recovery of phosinic acid wastewater, which was developed jointly by Sichuan Jinxiang Sairui Chemical Co., Ltd. (referred to as Jinxiang Company) and Sichuan Lvwo Innovation Environmental Protection Engineering Co., Ltd. (referred to as Lvwo Environmental Protection Company). An expert group composed of 12 senior experts from fields such as fertilizer industry, coal chemical engineering, and environmental protection, led by Gu Zongqin, president of the China Fertilizer Industry Association, unanimously concluded after evaluation that the project’s technical specifications are advanced, and its overall technology is at a leading level in China. 　　It is reported that the main innovations of this technology are as follows: First, an integrated multi-stage reverse osmosis membrane dilution and concentration technology has been developed. The reverse osmosis system features a flow-through type segmented pressure-increasing process, which ensures stable operating pressure for each membrane element, improves their operational efficiency, reduces the load of membrane fouling, and enables a service life of over 3 years. Second, develop high anti-fouling technologies for roll-type membrane elements to prevent high-concentration *ao acid an solutions from causing fouling of the membrane elements, thereby reducing the operational and maintenance costs of the equipment. Thirdly, the pH of the *ao acid wastewater is controlled at 6.8–7.2, and the temperature is kept between 25–35°C; this improves the retention efficiency of the reverse osmosis membrane for *ao acid. The concentration of the concentrated waste stream reaches 6–10%, while reclaimed water with a conductivity of ≤10 us/cm is obtained. Fourth is system automation control, which enables real-time collection, storage, and analysis of the operating conditions (parameters) of the equipment. This provides timely and comprehensive data analysis for system operation, facilitates automatic adjustments, and enhances the level of intelligence. It also allows for automatic control of the concentration ratio; when there are significant fluctuations in the process parameters of the materials fed into the device, this technology helps to reduce such fluctuations, thereby improving the stability and fault tolerance of the device. 　　The expert group believes that the research, development, and application of this technology are in line with the industrial policies aimed at **energy conservation, emission reduction, and clean production**, as well as with the industry’s goal of achieving **zero wastewater discharge**. It features a high concentration in the dense phase, good water quality in the clear phase, low investment and operating costs, and stable operation. 　　This technology has been successfully implemented in Chuanjinxiang Company over a period of three years, yielding valuable experience that makes it suitable for wider adoption. Gu Zongqin pointed out that, given the maturity and advancement of this technology, it is recommended to promote its use across the **industry. 　　The expert group also recommended that the implementing entity continue to develop this technology in order to increase the concentration of the concentrated phase to over 18%, and to minimize the amount of water introduced into the recovered concentrate, thereby reducing the energy consumption for evaporation in the system. 　　According to Li Xuchu, vice president and chief engineer of Chuanjinxiang Company, the company generates 1,000 m3 per day of phosphoric acid wastewater. Previously, ion exchange was used to treat this wastewater, but the main problems were manual operation, which increased the difficulty of managing staff, as well as unstable water quality in the treated output. Secondly, it is unable to withstand large-load impacts continuously, affecting the production stability of **. Third, the concentration of *ao acid in the recovered material is relatively low, at only 2-4%; the large amount of material recycled increases the load on the evaporator. 　　Li Xuchu said that the company, through analysis and investigation of the **wastewater treatment technology levels in the industry** as well as research on the application of special membrane separation systems by Greenwo Environmental Protection Company, decided to adopt a membrane filtration integrated system technology for the recovery and treatment of **wastewater**. The goals set were to achieve a **100% wastewater recovery rate, resulting in zero emissions; to prevent any secondary pollution during the treatment process; to keep the operating costs at no more than 3.5 yuan per ton of raw water; and to have an investment payback period of no more than 24 months. 　　Raw water conditions: Treatment volume of raw water is 38–40 m3/h; conductivity: 5000–8000 us/cm; pH value: 6.5–7.5; temperature: 25–35°C. After treatment, the specified parameters are achieved: the conductivity of the recycled fresh water is 5–30 us/cm (with a ** concentration of approximately 4.5–28 mg/L), while the conductivity of the recycled concentrated water is 100,000–120,000 us/cm (with a ** concentration of about 90–112 g/L). The operating load of the equipment can reach 110%. 　　After nearly three years of operational testing with the project’s equipment, it has been shown that under conditions of imported raw water, the conductivity of the treated water remains stable at around 10 us/cm (with a corresponding ** content of 9.2 mg/L), while the conductivity of the recycled concentrated water is between 100,000 and 120,000 us/cm (with a corresponding ** content of 90–112 g/L). The system operates stably, features fully automated control, and is simple yet reliable. 　　“The main vulnerable component of this device, namely the membrane, has a service life of over 3 years. The primary cost factor is electricity consumption, which is measured through separate metering. The overall treatment cost amounts to 2.31 yuan per ton of water. The investment required is 40% less compared to previous ion exchange systems; the payback period is less than 10 months. This approach truly enables our Chuanjinxiang Company to achieve **zero wastewater discharge**, thereby reducing the environmental pressure on the company. ”Li Xuchu said with confidence. 　　According to Qiu Quanguo, chairman of Lüewo Environmental Protection Company, the company’s membrane filtration integrated system for the recovery of phosphoric acid wastewater is compared in terms of performance with traditional wastewater treatment methods such as biochemical treatment, ion exchange, electrodialysis, and the electrodialysis+EDI approach. It features special separation membrane elements with high resistance to contamination; a membrane separation process system that results in a more concentrated concentrate phase and a clearer clear phase; and three technical advantages: one-button intelligent operation and control system. After nearly three years of verification regarding the continuous operation performance of the system, compared with Chuanjinxiang Company’s previous ion exchange technology, it has truly achieved **zero wastewater discharge.