High-recovery-rate saline wastewater membrane combination and separation process and application

Abstract

The invention discloses a high-recovery-rate saline wastewater membrane combination and separation process and an application thereof, and belongs to the technical field of water treatment and resource recycling. The process and the application comprise the following steps: a fiber filter is used to treat saline wastewater; then the saline wastewater is treated by an ultrafiltration membrane, and discharged water enters an ultrafiltration water tank; water in the ultrafiltration water tank is treated by a reverse osmosis membrance to obtain reverse osmosis clear water and reverse osmosis thick water, clear water is recycled, and thick water is treated by a nanofiltration membrane for further concentration; after the thick water is nano-filtered, nanofiltration clear water and nanofiltration thick water are obtained; the nanofiltration clear water enters the ultrafiltration water tank, and the nanofiltration thick water is collected and then applied to building materials or the coal washing industry. The separation process can also a physical washing and chemical cleaning unit and also selects a secondary reverse osmosis membrane assembly after primary reverse osmosis water production in order to adapt to different water quality requirements of discharged treatment water. Secondary reverse osmosis inflow water is primary reverse osmosis produced water, and secondary reverse osmosis thick water returns to the ultrafiltration water tank. The salt rejection rate is increased, and meanwhile the higher overall recovery is ensured.

Description

technical field [0001] The invention belongs to the technical field of water treatment and resource recycling, and particularly relates to a method and application for the treatment and recycling of saline wastewater based on a membrane combination process, and is especially suitable for underground brackish water, power plant circulating cooling sewage, and chemical industry containing wastewater. Treatment of saline wastewater. Background technique [0002] my country is a country that lacks fresh water resources, and the per capita fresh water possession is only 1 / 4 of the world's average level. . At the same time, the saline-alkaline geological conditions in Northwest China and the industrial structure dominated by coal mining and utilization, chlor-alkali and other chemical industries cause a large amount of saline wastewater to be discharged into the environment every year. Therefore, providing an efficient and economical saline wastewater treatment process and techno...

AI Technical Summary

Problems solved by technology

Due to the high filtration accuracy of the ultrafiltration membrane, most pollutants are likely to cause membrane blockage and fouling during the ultrafiltration process.

In addition, due to the limitation of the concentration ratio of the reverse osmosis membrane on the saline wastewater, a large amount of saline concentrated water is produced during the treatment process, resulting in low recovery of fresh water and other problems.

[0005] Zhao Peng et al. (CN101734820A) used the method of adding coagulation and sedimentation before membrane treatment to pre-treat wastewater to remove most of the suspended particles in the water and reduce the burden and damage of membrane treatment. However, the coagulation effect is affected by the water quality. And the type and dosage of the coagulant are severely restricted, and the colloidal precipitate formed by the residual coagulant can aggravate the membrane fouling. Therefore, increasing the pre-coagulation treatment to reduce the membrane fouling has been questioned by many

Yong Ruisheng et al. (CN101219836A) used deacidified and degreased walnut shells as filter materials to pre-treat oily wastewater with high salt content to remove most of the oil and suspended solids. However, the source of raw materials is limited and the treatment process is complicated. , low filtration accuracy, large water consumption for backwashing, etc.

[0006] For reverse osmosis concentrated water, multi-effect evaporation is currently used for treatment, but there are problems such as high energy consumption.

Secondary reverse osmosis is used to re-filter the primary reverse osmosis concentrated water to reduce the discharge of concentrated water. However, due to the high salt content of the primary reverse osmosis concentrated water, the secondary reverse osmosis requires a relatively high working pressure. The membrane tube , the pressure bearing capacity of water pipes will increase, thereby greatly increasing the cost of water treatment

In addition, although the return of reverse osmosis concentrated water to the front-stage ultrafiltration or nanofiltration can improve the recovery rate, increase the membrane surface flushing flow rate, and reduce fouling, the return rate must be controlled at a certain value, and this untreated concentrated water Direct backflow will seriously increase the salt concentration of reverse osmosis and its front stage nanofiltration, increase the burden on the membrane, affect the life of the membrane, reduce the efficiency of wastewater treatment, and increase the cost of the entire treatment process

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