RO seawater desalination machinery to meet domestic water needs

Working Principle: 

Under natural conditions, solvent molecules spontaneously diffuse from low-concentration solutions (freshwater) to high-concentration solutions (seawater), a phenomenon known as osmosis. Reverse osmosis technology uses a high-pressure pump to apply external pressure, making the pressure value exceed the osmotic pressure of seawater . This forces water molecules in the seawater to permeate in the reverse direction, passing through the semi-permeable membrane into the freshwater side. Meanwhile, salt ions such as sodium chloride and magnesium sulfate, as well as suspended impurities, organic matter, and microorganisms in the seawater are trapped by the membrane and discharged with the concentrate, ultimately achieving seawater desalination and purification.

Core Structural Components A complete reverse osmosis seawater desalination system consists of four parts: 

A pretreatment system, a core reverse osmosis system, a post-treatment system, and auxiliary systems. These modules work together to ensure stable operation and high-quality produced water. The specific structure is as follows:

- Pretreatment System: As the "pre-protection barrier" for the equipment, its core function is to remove suspended particles, colloids, residual chlorine, organic matter, and calcium and magnesium ions from seawater, preventing subsequent reverse osmosis membrane fouling, scaling, or damage, and extending membrane lifespan. Main components include a multi-media filter (removing 5-10μm suspended particles) and 1μm & 5μm security filters. Seawater has a very high hardness index, with calcium and magnesium ion content exceeding 10,000 ppm. Therefore, a water softener cannot be used directly to remove hardness; scale inhibitors must be added. In some high-turbidity, high-algae seawater scenarios, an ultrafiltration (UF) device will be added to ensure that the surface water pollution index (SDI) after pretreatment is ≤3, meeting the requirements of the reverse osmosis system.

- Core Reverse Osmosis System: The "core membrane system and pump set" of the equipment determines the efficiency and quality of seawater desalination. It mainly includes high-pressure pump sets, reverse osmosis membrane modules, and energy recovery devices. The high-pressure pump provides an operating pressure of 4.5-7.5 MPa (5.5-6.5 MPa for conventional seawater, 6.5-7.5 MPa for high-salinity/low-temperature seawater), commonly using multi-stage centrifugal pumps or plunger pumps, and equipped with frequency converters to adapt to fluctuations in water temperature and salinity. The reverse osmosis membrane modules are mainly polyamide composite membranes (approximately 200 nm thick, pore size 0.1-1 nm), with spiral wound arrangement being the primary method (accounting for 90% market share). A single membrane can achieve a desalination rate of over 99.7%. The energy recovery device (such as a PX pressure exchanger) can recover the pressure energy of the concentrate, achieving energy savings of over 30%, making it a key component for reducing equipment energy consumption.

- Post-treatment system: Deeply treats the freshwater produced by reverse osmosis to meet the water standards of different scenarios. The main components include pH adjustment device and ultraviolet sterilizer. Generally, primary RO treatment is suitable for ordinary domestic water. Some drinking water scenarios require secondary RO system. Industrial water scenarios may be equipped with secondary RO + EDI/mixed bed to further reduce conductivity and ensure that the produced water quality meets the standards.

Guangzhou Kaiyuan has 20 years of professional experience in customizing seawater desalination equipment, offering capacities from 1 to 2000 tons per day. Water quality can be designed according to customer requirements.