Functions, types and maintenance of pure water equipment
① what types of strainers are there
according to the size of the filtered water, the most common types of primary filters are sand filters, non-woven fabric filter elements and PP fiber filter elements. The most commonly used lengths of non-woven fabric filter elements and PP fiber filter elements are 10 inches and 20 inches. The pore diameter of the filter element used as a primary filter is generally about 25U
② what is the effect of incorrect processing of long fiber composites by the strainer
the coarse filtration experimental machine has mechanical, hydraulic, electro-hydraulic or electronic servo types. Its function is to remove suspended impurities with large particle size in water, prevent these impurities from entering the activated carbon filter, cover the surface of activated carbon, and make the pore structure of activated carbon lose the ability to adsorb impurities in water
③ why and how to maintain the strainer
with the increase of solid impurities intercepted, the resistance of the coarse filter rises sharply and the water flow decreases gradually. If it is not treated in time, it cannot meet the water flow requirements of the subsequent treatment process. For sand filter, backwash in time after the pressure rises to a certain extent. During backwashing, some fine sand is washed out of the filter, so the sand filter should be regularly supplemented with sand. After repeated backwashing, the degree of crushing of the sand increases. At the same time, it is impossible to wash 100% of the sand every time, the remaining silt in the sand gradually increases, and the sand layer will appear plate formation. At this time, the sand layer should be replaced. For non-woven fabric or PP fiber filter element, if the filter hole is blocked, the experiment cannot be carried out. Generally, it is difficult to flush it with water, and the filter element must be replaced regularly
2. Activated carbon filter
① what is the function of activated carbon filter
activated carbon filter is mainly used to remove macromolecular organics, iron oxides and residual chlorine. Organic matter, residual chlorine and iron oxide are easy to poison the ion exchange resin, while residual chlorine and cationic surfactant will not only poison the resin, but also destroy the membrane structure and make the reverse osmosis membrane invalid
② why should the activated carbon filter be maintained
the activated carbon filter uses the rich pores of the activated carbon to adsorb and filter the colloidal substances such as macromolecular organics, residual chlorine and iron oxide in the water. This adsorption is irreversible, that is, the activated carbon has a certain saturated adsorption capacity. Once the adsorption is saturated, the activated carbon loses its adsorption performance and cannot be washed away by backwashing. In addition, after the activated carbon adsorbs organic matter, it provides rich nutrition for bacteria, causing bacteria to multiply in large numbers in the activated carbon filter, and the microbial content in the water increases after the activated carbon filter
③ how to maintain the activated carbon filter
before the adsorption of activated carbon is saturated, backwash regularly to flush out a large number of bacteria and suspended solids on the surface of activated carbon. After the adsorption of activated carbon is saturated, the activated carbon should be replaced immediately, otherwise it will cause irreparable damage to the reverse osmosis membrane
3. Water softener
①. What is the function of water softener
the function of water softener is to remove calcium and magnesium ions in water and soften water. If there is no water softener or the water softener fails, calcium and magnesium salts form water-insoluble sediments on the surface of the reverse osmosis membrane due to the sharp increase in concentration,
block the pores of the reverse osmosis membrane, shortening the service life of the reverse osmosis membrane
② why and how to maintain the water softener
water softeners for pure water generally use sodium cation exchange resin, which is regenerated with salt after resin exchange saturation. After several years of use, the resin is more and more broken, and gradually loses its softening ability. Especially when the activated carbon is saturated through the
filter and the activated carbon is not replaced in time, the iron, organic matter and residual chlorine in the raw water will directly enter the water softener, poisoning the resin. Once the resin is poisoned, it cannot be reactivated by regeneration
when the working exchange capacity of the resin decreases significantly, the resin should be replaced
4. Reverse osmosis is the core component of the pure water system. The raw water that has been pretreated and meets the requirements of reverse osmosis membrane becomes pure water after reverse osmosis
filtration. Therefore, doing a good job in the maintenance of reverse osmosis is the key to ensure the quality of pure water. During the operation of reverse osmosis membrane, the salt concentration on the membrane surface is higher than that in the main fluid. This phenomenon is called concentration polarization. The consequence of concentration polarization is to make some salts precipitate on the membrane surface, block the water production channel of reverse osmosis membrane, and reduce the water production of membrane. Organic matter in the feed water will deposit on the membrane surface when it is not washed continuously or washed regularly, especially some reverse osmosis membranes with charge on the surface will attract charged organic matter and stick it on the membrane surface. The deposition of organic matter on the film surface causes more serious damage to the film in the mold forming process than the deposition of salt on the film surface. Sometimes this damage is irreversible. The concentration of organic matter and various salts on the membrane surface is much higher than that of the main water flow, which provides rich nutrition for the reproduction of bacteria. A large number of microbial colonies not only block the water production channel, but also because the reverse osmosis membrane itself is also an organic matter, it will be decomposed by microorganisms, causing irreversible damage. Oxidizing substances in water, such as residual chlorine, are enriched on the membrane surface. After enrichment to a certain extent, they exceed the concentration that the membrane itself can withstand, and the reverse osmosis membrane will be oxidized and decomposed
all the above factors make the water production of reverse osmosis membrane gradually decrease, the salt permeability gradually increase, and the quality of pure water decline. Generally, the service life of reverse osmosis membrane is three years. The reverse osmosis membrane should be replaced in time after it is damaged, otherwise it will not only affect the water production, but also deteriorate the water quality
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