1. Heavy metal wastewater treatment
RO Technology is used earlier in the treatment of heavy metal wastewater, and a lot of research has been carried out at home and abroad. As early as the 1970s, RO Technology has been applied in electroplating wastewater treatment, mainly for large-scale treatment of nickel, chromium, zinc rinse water and mixed heavy metal wastewater.
Mohsenniaa added Na2EDTA to chelate Cu2 + and Ni2 + ions, and then through ro filtration, the ion retention of Cu2 + and Ni2 + can be increased to 99.5%. Covarrubias, Bo dallo, etc. used RO membrane to treat tannery wastewater. The results showed that RO membrane had a high removal rate of chromium and organics in leather industry wastewater.
Changsha Liyuan new materials Co., Ltd. uses membrane separation technology to concentrate nickel plating rinse water. The retention rate of nickel ion is more than 99%. After one-stage nanofiltration and two-stage ro concentration, the concentration of nickel ion in the concentrate reaches 50g · L-1. The permeate can be reused after treatment. Zhang Liankai adjusted the pH of the heavy metal wastewater from the pickling workshop of printed circuit board to neutral and then used ultrafiltration + RO process for pilot test. The removal rate of Cu2 + and total dissolved solid by RO system was 99.9% and 98.9%, respectively.
2. Dyeing wastewater treatment
Printing and dyeing textile wastewater not only has high chroma and large water volume, but also has complex components. The wastewater contains dyes, size, oil, additives, acid and alkali, fiber impurities, inorganic salts, etc. the dye structure also contains a lot of more biotoxic substances, such as nitro and amine compounds and heavy metal elements such as copper, chromium, zinc, arsenic, etc. if it is discharged directly without treatment, it will certainly affect the environment Cause serious pollution.
Zeng Hangcheng used ultrafiltration + ro double membrane technology to treat printing and dyeing wastewater. Ultrafiltration can effectively remove macromolecular organics in wastewater, reduce turbidity, and make the water quality meet the requirements of RO membrane. After RO treatment, the removal rate of organics and salts can reach 99% and 93% respectively. The chemical oxygen demand of water production is less than 10mg · L-1, and the conductivity is less than 80 μ s · cm-1. The water production meets most of the printing and dyeing process water consumption Standards. Zhongjing uses hollow fiber ultrafiltration membrane and RO Technology to treat wool printing and dyeing wastewater. Under the condition of operating pressure of 0.1MPa and flow rate of 1500L · H-1, the indexes of chroma and salt content are significantly reduced, COD value and chroma meet the discharge standard.
3. Treatment of Circulating Wastewater in power plant
The circulating cooling water system of the power plant consumes a large amount of water, accounting for 80% of the pure thermal power plant water and more than 50% of the thermal power plant water. The circulating discharge water is recycled and treated. As the water source of the circulating make-up water or boiler make-up water system, the produced water can not only prevent environmental pollution, but also effectively save water resources and reduce production costs.
Beijing Jingfeng natural gas turbine combined cycle power plant adopts the combined operation of ultrafiltration and RO Technology to treat the circulating sewage of the power plant. Since its operation, the RO system has operated well with a water yield of 68m3 · H-1, a conductivity of less than 35 μ s · cm-1 and a desalination rate of more than 97%. The desalted water station of the power plant of Handan Iron and Steel Group Co., Ltd. also adopts the double membrane water treatment process. The refined desalted water after ultrafiltration + secondary ro + mixed bed treatment can be used by the boiler and CDQ in the power plant, with a daily output of 150000t of refined desalted water. In addition, in Linyi Power Generation Co., Ltd., Guo Qing  conducted a field test on the treatment of Circulating Cooling Wastewater by the combined process of ultrafiltration and ro. The operating pressure of each section of the RO system was stable, and the produced water met the requirements of reuse. Chen Yingmin used continuous microfiltration + RO Technology to pre desalting the circulating sewage. The desalting rate of RO system was over 98%.
4. Chemical wastewater treatment
In the process of producing K2CO3 by ion exchange, a large amount of NH4Cl waste water will be produced. In order to save water and thoroughly solve the problem of NH4Cl waste water discharge, Zhang Jizhen adopts the method of combining ion exchange, RO membrane separation and low-temperature multi effect flash evaporation to further concentrate and recover the low concentration NH4Cl waste water, so as to make the waste water from the discharge up to the standard to be completely recycled and achieve zero discharge 。
The composition of petrochemical wastewater is complex. It contains not only oil, sulfur, benzene, phenol, cyanogen, naphthenic acid and other organic matters, but also metal salts, reaction residues, etc. the concentration of pollutants is high and difficult to degrade, and the water volume and pH fluctuate greatly. The traditional water treatment process is difficult to achieve the purpose of resource recovery and reuse. The 500 t · H-1 desalted water unit newly built by Lanzhou Petrochemical Company in 2006 has stable operation in 5 years, high desalting rate and good effect. Li Yuhang used ultrafiltration + ro double membrane method to recycle petrochemical wastewater. The water produced by ultrafiltration system is sdi99%, and the water produced at the end meets the water quality requirements of circulating cooling and make-up water.
Generally, RO, as the terminal treatment of industrial wastewater, has a high rejection rate for inorganic salt, organic matter and heavy metal ions in the water. The effluent quality is excellent and can be reused as cooling water or process water for recycling. It not only saves the use of fresh water, saves production costs, but also reduces the discharge of sewage. It is of great significance for environmental protection and sustainable development Water shortage areas have great economic benefits.