A complete water treatment system consists of three main parts: pre-treatment system, precision treatment system, and post-treatment system. After passing through pre-treatment systems such as PP filter element (sand rod filter), activated carbon unit, and water softener unit, the content of suspended solids (particulate matter), colloids, hardness, microorganisms, and other impurities in the water is greatly reduced to reduce the processing load of subsequent precision treatment systems such as reverse osmosis and electric desalination, and extend their service life.

 

Activated carbon has a large specific surface area and is filled with micropores with extremely small pore sizes (10-30 angstroms). Colloids, residual chlorine, iron ions, etc. have significant adsorption and filtration effects. Desktop pure water machines, water purifiers, and other commonly used 10 inch/20 inch activated carbon filters. Activated carbon filter tanks made of fiberglass/stainless steel are commonly used in large pure water units.

 

The pore size of reverse osmosis membranes is as small as the nanometer level (1 nanometer=10-9 meters). Under a certain pressure, H2O molecules can pass through the RO membrane, while impurities such as inorganic salts, heavy metal ions, colloids, bacteria, viruses, etc. in the source water cannot pass through the RO membrane, thus strictly distinguishing between permeable pure water and impermeable concentrated water.

 

The RO membrane has a removal rate of over 99% for high valence ions, colloids, bacteria, and substances with a molecular weight greater than 300 daltons (including heat sources), and a removal rate of 95% for low valence ions (NA+, K+). When the source water conductivity is less than 3505 μ s/cm, the RO pure water conductivity is usually ≤ 55 μ s/cm, which meets the national third level water standard. After circulating and filtering through atomic level ion exchange columns, the effluent rate can reach 18.2 M Ω· cm. Reverse osmosis is an economical method that can achieve impurity removal rates of 90% to 99%, and it is also a good pretreatment method for reagent grade ultrapure water systems.

 

Note: The filtration capacity of RO membrane is greatly affected by water temperature. The suitable water temperature is 25 ℃~30 ℃. When the temperature drops by 1 ℃, the water production of RO membrane decreases by about 3%. When the water temperature approaches 0 ℃, the RO membrane will stop producing water.