Probable Problems in the Use of Cation Exchange Resin in Sichuan Province

　　Problems that may arise in the use of cationic exchange resins in Sichuan Province? Chengdu Senger Environmental Protection Technology Co., Ltd.

　　1. Damage of flow passage

　　Ion exchange resin leaks from the equipment and enters the later equipment or water supply system, which makes the operation of the latter equipment difficult and deteriorates the quality of the effluent water.

　　2. Organic Pollution

　　Resin contaminated by organic matter is the main problem in water treatment. With the pollution of natural water becoming more and more serious, the pollution of resin has brought a great threat to water treatment. The more alkaline the resin is, the more serious the organic pollution is. The greater the ratio of organic matter to strong acid anion in the influent is, the greater the degree of resin pollution is.

　　The order of organic contamination degree of Sichuan anion exchange resin resin is as follows:

　　Gel strong base type I > macroporous strong alkali type 1 > strong alkaline type II > weak base.

　　It can be said that the pollution of strong alkali anion exchange resin for organic matter is very common, which needs to be taken seriously.

　　Ion exchange resins may be deteriorated by oxidants such as free chlorine in the influent during operation. This deterioration can not be recovered. It may also be contaminated by foreign impurities and change its performance, affecting the quality of effluent and periodic water production. However, appropriate measures can be taken to clarify the pollutants and restore or improve the properties of the resin.

　　3. Layering of resin is not clear

　　For example, mixing bed requires that the two resins can be well stratified, otherwise the water production and effluent quality will be reduced. In serious cases, the effluent will not meet the required target.

　　There are many reasons for the occurrence of lipid mixing, mainly in the following situations:

　　(1) Operation and equipment problems. When the flow is not uniform, deviations (possibly due to damage or fouling of local flow area) and improper backwashing operation, and resin stratification is not good, equipment should be checked or re-operated.

　　(2) The resin is polluted and its density increases. Resin layer is polluted by iron, calcium scaling, or organic pollutants, which will increase the resin density and affect the stratification effect.

　　(3) The lower resin is broken, and the fragmented resin is not easy to be stratified with the upper resin. At this time, they should be separated by desalted water and the fragmented resin should be removed.

　　(4) Small-scale tests and particle settling velocities must be carried out before the new resin is loaded to verify whether the particle size and density of the selected resin are suitable for hydraulic stratification and to remove the fine-grained resin when the resin is loaded.

　　4. Pollution of Turbidity on Anodic Resin

　　When the turbidity of influent exceeds the requirement or DC coagulation occurs, more suspended solids will pollute the resin when they enter the * ion exchanger. These suspensions often contain coagulants, usually salts of high-valent metal ions. These suspended solids are difficult to remove during regeneration and backwashing. They are often removed by backwashing with large flow of water (but resin loss should be prevented), air scrubbing and dissolution of hot concentrated hydrochloric acid solution.

　　5. Calcium sulphate precipitation

　　When using sulfuric acid to regenerate anodic resin, if the concentration of sulfuric acid is too high and the flow rate is too slow, calcium sulfate will deposit on the surface of resin particles, resulting in hardness of the effluent. At this time, hydrochloric acid can be regenerated once to dissolve the deposited sulfuric acid, or rinse in time with a large amount of water.

　　6. Iron Pollution

　　Both anionic and anionic resins are polluted, but the mechanism of iron contamination is different between the two resins. In the first stage desalination equipment, the cationic resin contacts the products and corrosion products which are coagulated with iron ions and iron ions in raw water. When iron ions in water are absorbed by positive resin, it is difficult to regenerate. Corrosion products become iron ions when regenerated. At lower regeneration dosage, they will be absorbed by resin at the outlet. Ferric ion pollution will make the color darker, accelerate oxidation degradation, performance gradually reduced, water quality deteriorated, water quantity reduced; anion resin polluted by iron is different, often from the regeneration solution brought iron deposited on anion resin, and combined with silicon, organic matter and so on into a complex material form, so that anion resin is polluted. Dyeing, and the pollution is cumulative. Mixed bed resin is also seriously polluted, especially when the machine and furnace have just been put into operation and restarted after a long period of shutdown, it will bring in a large amount of iron oxide, which will pollute the resin.

　　7. colloidal silicon

　　Colloidal silicon is a phenomenon of improper regeneration of strong alkali anion resin. When the ratio of silica to strong acid anion in raw water is large or weak alkali anion resin absorbs strong acid in water, colloidal silica may occur in anion resin regeneration. Generally, this phenomenon is more likely to occur when the concentration of alkali solution is higher and the temperature and flow rate are lower. Colloidal silicon usually appears in the resin layer at the outlet of regenerated liquor, which is due to the sharp decrease of p_of regenerated alkali liquor at the outlet, forming the environment of gelled silicon.

　　The method of preventing the occurrence of colloidal silicon is as follows:

　　(1) Preheated resin bed;

　　(2) The regeneration method is that the regeneration liquid is diluted first, then concentrated, and the flow rate is fast and then slow.

　　(3) Discharge part of the initial regeneration waste liquid from the middle of the resin layer, etc.

　　The colloidal silicon in the resin layer will affect the effluent quality, and the silicon emission will occur in the long running time. Once the phenomenon of desilication occurs, it can be dissolved in dilute temperature and alkali.

　　8. Thermal degradation

　　The water temperature in the normal primary desalted water treatment system is not high (even if the water temperature in summer is not higher than 40 C in the south of China), in principle, it will not cause serious degradation of type I strong alkali anion resin. However, due to the poor cooling effect, the condensation water temperature can be as high as about 60 C, which is not conducive to the mixed bed anion resin. Strong alkali resin for a long time

　　9. Backwashing loss

　　Resin loss occurs when the backwashing flow is too large or the backwashing operation is abnormal. A large number of resins are often found in ditches and wastewater pools.