1,What is seawater desalination?
Seaater Desalination uses reverse osmosis technology to separate water molecules from seawater. Water from the ocean is forced through thousands of tightly-wrapped, semipermeable membranes under very high pressure. Desalination is one of the main ways to obtain fresh water in many coastal countries, especially those in the Middle East with high temperature and drought. Reverse osmosis system is currently used to do a widely used desalination system.
The pretreatment of reverse osmosis generally includes coagulating sedimentation, coarse filtration, Microfiltration, ultrafiltration, etc.
2,The sea water is fed with medicine (flocculant, coagulant aid) through the mixer and then enters the flocculation tank for flocculation reaction. The effluent of the flocculation tank enters the sedimentation tank for solid-liquid separation, and the supernatant liquid of the sedimentation tank is the effluent of the flocculation sedimentation process. It is mainly to remove impurities such as sediment, suspended matter, seaweed and other large particles in seawater.
3. Coarse Filtration
Coarse filtration generally uses multi-media filter housings and activated carbon filter housings. Multi-media filter housings are mainly used to remove suspended solids, colloids and other impurities and algae and other organisms in seawater. The activated carbon filter housing mainly absorbs the peculiar smell, organic matter, colloid in the seawater, thereby reducing the turbidity and chromaticity of the water, and achieving the effect of purifying the water quality.
The microfiltration system is generally composed of a security filter housing and filtering consumables. The security filter housing can be combined indefinitely according to the required water output. Due to the high salt content of seawater, the security filter housing in the microfiltration system generally uses a fiber reinforced plastics filter housing with strong corrosion resistance. The filtering consumables generally choose High Flow Filters, Melt Blown Cartridges or String Wound Cartridges with 5 micron filtration rating. Its main purpose is to filter the suspended solids, colloids, microorganisms and other impurities larger than 5 microns in seawater.
The ultrafiltration system is generally the last pretreatment process to protect the reverse osmosis system. The ultrafiltration system generally selects the Ultrafiltration Membrane Module made of PVDF hollow fiber membrane and UPVC material membrane housing, which can intercept impurities with a particle size greater than 0.1 micron, reduce the impurities in the reverse osmosis water, and extend the reverse osmosis membrane service life.
In the process of seawater desalination, the design of reverse osmosis pretreatment is determined according to the type of seawater source and water quality. If the seawater quality is poor, higher costs are required to complete the seawater desalination and desalination process. Therefore, we should choose places with better water quality to build desalination plants as much as possible.