Combined membrane separation technology: a case of zero discharge treatment of high-salt wastewater

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The combined membrane separation technology is an efficient and flexible solution to achieve zero discharge in the treatment of recycled saline wastewater. Through the cooperation of different types of membrane components, it can remove various pollutants in wastewater and realize resource utilization.

Case background:
A salinization plant in Shandong province produced a large amount of highly saline wastewater containing chlorides, sulfates and other salt compounds. Since the wastewater could not be discharged directly or used for other purposes, it was decided to use the double membrane method for wastewater treatment to achieve the goal of zero discharge.

Processing process:
Pretreatment →NF→ Reverse osmosis
Pretreatment →NF→ Reverse osmosis
High salt wastewater wastewater is first passed through a coarse sieve and sedimentation tank to remove large particles of suspended matter and sediment, reducing pollution to subsequent membrane elements. The pH value of the wastewater is adjusted through the chemical neutralization process to prevent acid and alkali corrosion and pollution of the membrane.

Primary nanofiltration (NF)
The wastewater is passed through the first-stage Dalton NF membrane system, which effectively removes most salts, organic matter and microorganisms from the water. The water quality after NF membrane treatment is relatively good, and the organic-rich part is left in the wastewater.

Intermediate processing step
Filtration, neutralization or other chemical treatment to further purify the water and remove remaining organic matter.

Second stage reverse osmosis (RO)
The treated water passes through a second-stage Dalton RO membrane system, which has a smaller pore size than NF and effectively removes residual salts and other tiny dissolved substances from the water.

Post-processing and recycling
The treated water goes through a final post-treatment step to ensure that the water quality meets environmental discharge standards.

Effects and Advantages:
By using the double membrane process, the plant has successfully treated high-salt wastewater into water quality that meets environmental discharge standards and has achieved zero discharge. The salt in the wastewater is efficiently removed, and the fresh water generated can be used for industrial production, reducing the dependence on natural water bodies. The combination of nanofiltration and reverse osmosis makes the wastewater treatment more comprehensive and efficient.

With the continuous progress and innovation of science and technology, there are many challenges facing the current zero discharge of saline wastewater.

Daltonen continues to be committed to developing new efficient and low-cost wastewater treatment technologies and equipment, exploring more energy-efficient and efficient membrane separation integration processes, optimizing the overall design of zero-discharge systems, improving resource recovery rates, reducing energy consumption and costs, achieving double improvement of economic and environmental benefits, and promoting the chemical industry to green sustainable development.

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