Introduction to Ultrapure Water System Pretreatment

Pretreatment in ultrapure water systems removes particulate matter, colloids, residual chlorine, and calcium and magnesium ions from the water, protecting the reverse osmosis system. Common pretreatment components include:

1. PP (Polypropylene Meltblown Filter): With a gradually tightening structure (loose on the outside, tight on the inside), and a filtration pore size of 5 microns, it effectively removes various particulate impurities from the filtered liquid, blocking large particles such as rust, sediment, and insect eggs. Common sizes are 10-inch and 20-inch, but 5-inch and 30-inch sizes can also be provided according to actual needs.

2. PL (Wound Filter): Made by winding polypropylene or degreased cotton threads onto a polypropylene frame using a special process. The wound filter's structure is loose on the outside and tight on the inside, effectively filtering suspended solids and rust from the liquid. Compared to PP, it has a stronger dirt-holding capacity, but its filtration effect is relatively weaker. Common sizes are 10-inch and 20-inch.

3. Activated Carbon: Effectively removes residual chlorine, organic matter (500~6000 Daltons), heavy metals, and off-colors and odors. High-quality acid-washed activated carbon is commonly used in pure/ultrapure water preparation processes; it has a large specific surface area, abundant porosity, and strong filtration effect. Activated carbon is available in various sizes depending on the manufacturing process and water treatment requirements: compressed activated carbon filter cartridges (AC), commonly 10-inch and 20-inch sizes; granular activated carbon filter cartridges, also commonly 10-inch and 20-inch sizes; and activated carbon canisters of various models and sizes.

4. KDF: High-purity copper/zinc alloy. Effectively reduces or removes chlorine and heavy metals from water through an electrochemical oxidation-reduction (electron transfer) reaction, and inhibits the growth and reproduction of microorganisms in the water.

5. Chlorine Remover: Ca2SO3. Effectively removes residual chlorine through a reduction reaction.

6. Quartz Sand: Quartz sand is made of silicon dioxide crystals and is commonly used as the packing material in mechanical filters in ultrapure water systems to treat source water with high turbidity and suspended solids. By filling the filter media with quartz sand of different mesh sizes, flow pores of varying sizes are formed between the particles, effectively intercepting particulate impurities and suspended solids in the source water.

7. Manganese Sand: Manganese sand is a water treatment filter media with an MnO2 content of not less than 35%. Utilizing the anti-ferrocatalytic effect of manganese sand itself, it catalyzes ferrous iron in the water to ferric iron, which then adheres to the surface of the manganese ore particles, thus achieving iron removal.

8. Softening Resin: Through ion exchange, it removes large amounts of Ca2+ and Mg2+ from the water, reducing water hardness. Softening resin requires regeneration during use.

9. Flocculant: Primarily used at the front end of multi-media filters to remove colloidal substances and fine particles.

10. Scale Inhibitor: Mainly for water with high alkalinity, high hardness, and high pH, effectively controlling carbonate and sulfate scale buildup in reverse osmosis systems.

11. Bactericide: A highly effective broad-spectrum bactericide used to control the growth of microorganisms throughout the reverse osmosis system.