The basic working principle of reverse osmosis is as follows: A specially designed high-pressure water pump pressurizes the raw water to 6-20 kg, forcing it to permeate through a reverse osmosis membrane with a pore size of only 0.0001 micrometers. Chemical ions, bacteria, fungi, and viruses cannot pass through and are discharged with the wastewater. Only water molecules and solvents smaller than 0.0001 micrometers are allowed to pass through.
The security filter contains filter cartridges with a pore size of 5 μm. These cartridges filter out any particles larger than 5 μm, protecting the downstream RO membrane, which is prone to scaling. A commonly used type of reverse osmosis membrane is the polyamide membrane, specifically a spiral-wound composite membrane. This type of membrane can achieve a desalination rate of up to 99.5%.
Because RO membranes are susceptible to changes in pH, residual chlorine, and water temperature, strict requirements are placed on the influent water quality before operation:
PH: 3~10
Residual chlorine: < 0.1mg/L
SDI15: < 5.0
Water temperature: < 45℃
Exceeding any of these limits may cause membrane deformation, affecting effluent quality and shortening membrane lifespan. Furthermore, different types of membranes have different influent water quality requirements. These requirements should be confirmed according to the instructions provided by the RO membrane manufacturer before commissioning.