The core process of pure water machine and ultrapure water machine (2) UV sterilization, ultrafiltration and microfiltration technology

l UV (ultraviolet sterilization)

The UV lamp used in the water purifier is a low-pressure mercury lamp. Like ordinary fluorescent lamps, it is excited by low-pressure mercury vapor to emit ultraviolet rays. The emitted ultraviolet light has two peaks of 254 nm and 185 nm . The difference between a UV lamp and a fluorescent lamp is the lamp. The tube of the fluorescent lamp is made of ordinary glass, and the ultraviolet light of 254 nm cannot be penetrated. The tube of the UV lamp is made of quartz glass, and the ultraviolet rays of each band can be well penetrated.

254nm ultraviolet light has a good bactericidal effect. This is because the cell has a regular absorption line for light waves. The ultraviolet light at 250~270nm has the largest absorption. The absorbed ultraviolet light actually acts on the genetic material of the cell, ie DNA . To a photochemical effect, the energy of the ultraviolet photon is absorbed by the base pairs in the DNA , causing the genetic material to mutate, causing the bacteria to die immediately or not to breed, and achieve the purpose of sterilization.

185nm UV light can degrade organic matter. Studies have shown that ultraviolet light with a wavelength of 185 nm can interact with water, causing a homogenization reaction of water, producing a reactive intermediate hydroxyl radical. Hydroxyl radicals are highly oxidizing, causing degradation and mineralization of organic matter in water, thereby lowering the TOC concentration and achieving the effect of degrading TOC in water .

l UF ( Ultrafiltration )

Ultrafiltration uses membrane filters with pore sizes typically ranging from 1 to 10 nanometers to remove particles of protein size . Ultrafiltration membranes of hollow fiber structure generally have a higher filtration rate.

Ultrafiltration membranes are typically installed close to the outlet of the pure water meter to reduce the concentration of microorganisms and organic macromolecules, including nucleases and endotoxins. Ultrafiltration membranes must be cleaned and replaced periodically to maintain their performance. Ultrafiltration can be installed in a conventional manner, with all water flowing straight through the membrane or, in a better way, tangential flow, with a portion of the horizontal flow passing through the membrane surface to remove contaminants to reduce clogging of the membrane surface. .

For the protection of ultrapure water quality remained stable on the indicators particles, bacteria and heat content, etc., UF is an excellent technology.

l MF ( microfiltration )

Microfilters in pure water systems physically block particulate matter and microorganisms in water. The microfilter is completely classified according to the size of the particles, has a relatively uniform molecular structure, and retains all particles larger than the surface pore size.

Microfilters ( 0.1-0.22 μm ) are usually placed as close as possible to the point of water withdrawal to capture microorganisms and fine particles.

The trapped particulate matter, including microorganisms or their metabolites and soluble materials, may be leached out of the filter again, so proper maintenance of the microfilter (regular disinfection and periodic replacement) is necessary to maintain its performance at a desired level.