Reverse osmosis (RO) treatment device

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Scope of use Seawater, brackish water desalination； Medium and high pressure boiler feed water ； Food and beverage pure water ； Bottled pure water pipe quality-separated water supply, etc. Cleaning standards for membrane fouling 1.1 Under normal pressure, the product water flow rate drops to 85 to 90% of the normal value ； 1.2 In order to maintain normal product water flow, the feed water pressure after temperature correction is increased by 10 to 15% compared with normal operation. ； 1.3 The product water quality is reduced by 10-15%, and the salt permeability is increased by 10-15%. ； 1.4 The pressure difference between each RO section increases significantly. Common pollutants and cleaning methods 2.1 Calcium carbonate scale: 　　When the antiscalant addition system fails or when the acid addition system fails, the pH value of the water increases, then calcium carbonate may precipitate. The occurrence of calcium carbonate scale deposition should be discovered as early as possible to prevent the grown crystals from operating on the membrane surface. If calcium carbonate scale is discovered early, it can be removed by lowering the feed water pH to between 3-5 and running for 1-2 hours. 　　For calcium carbonate scale that has a longer precipitation time, 2% citric acid cleaning solution (control pH not less than 4) should be used for cleaning. Note: You should ensure that the pH of any cleaning solution is not lower than 4, otherwise it may cause damage to the RO membrane element. You should pay more attention especially when the temperature is high. The highest pH value should not be greater than 10. You can use sulfuric acid or hydrochloric acid to reduce the pH value, and use sodium hydroxide to increase the pH value. 2.2 Calcium sulfate scale : 　　Cleaning solution 2 (see Table 2) is the best way to remove calcium sulfate scale from the reverse osmosis membrane surface. 2.3 Metal oxide scale: 　　Deposited hydroxides (such as ferric hydroxide) can be easily removed using the calcium carbonate scale removal method described above. 2.4 Silicon scale: 　　For silicon scales that are not symbiotic with metal oxides or organic matter, they can generally be removed only through specialized cleaning methods. Please contact our company for detailed methods. 2.5 Accumulated sediments: 　　Organic sediments (such as microbial slime or mildew) can be removed with cleaning fluid. In order to prevent regeneration and reproduction, the company's approved sterilizing fluid can be used to circulate and soak in the system. Generally, it takes a longer period of soaking to be effective. If the reverse osmosis device is out of service for more than three days, it is best to use detoxification treatment. 2.6 Selection of cleaning fluid: 　　When cleaning reverse osmosis membrane elements, it is recommended to use the cleaning fluid listed in Table 2. It is very important to conduct chemical analysis of contaminants before determining the cleaning solution. Detailed analysis and comparison of the analysis results can ensure the selection of the best cleaning agent and cleaning method. The cleaning method and the cleaning effect obtained during each cleaning should be recorded to provide a basis for finding the best cleaning method under specific water supply conditions. It is recommended to use 1# cleaning fluid for inorganic pollutants, and 2# cleaning fluid for calcium sulfonyl and organic pollutants. It is recommended to use 3# cleaning fluid to severely punish organic contamination. All cleaning solutions can be cleaned at a temperature of 40°C for 60 minutes. The required amount of supplies is based on the amount added per 379 liters. When preparing the cleaning solution, add chemicals and cleaning water (reverse osmosis fresh water) in proportion and mix evenly. During the reverse osmosis membrane cleaning process, the cleaning solution is circulated on the high-pressure side of the membrane at low pressure and large flow rate. At this time, the membrane element is still installed in the pressure vessel, and a special cleaning device is required to complete the work. 　　General steps of cleaning process: 3.1 Use a pump to pump clean, free chlorine-free reverse osmosis fresh water into the pressure vessel and allow it to drain for a few minutes. 3.2 Use reverse osmosis fresh water to prepare cleaning fluid (see Table 2 for details). 3.3 Circulate the cleaning fluid in the pressure vessel for 1 hour or a preset time. For an 8-inch pressure vessel, the flow rate is 35 to 40 gallons/min (8 to 9m3/H). 3.4 After the chemical washing is completed, drain the remaining liquid in the medicine box, clean it, and then put in reverse osmosis fresh water. 3.5 Use a pump to pump the fresh water in the medicine tank into the pressure vessel and let it drain for a few minutes. 3.6 After flushing the reverse osmosis system, open the freshwater outlet discharge valve of the reverse osmosis system and put the reverse osmosis system into normal operation. After 15-30 minutes, check the quality of the freshwater discharge water (no foam, no cleaning agent, and the conductivity meets the standard). 3.7 Open the fresh water outlet valve of the reverse osmosis system, close the fresh water outlet discharge valve, and resume normal operation. Table 1 Characteristics of reverse osmosis membrane pollution and treatment methods. General characteristics of pollutants. Treatment method 1. Calcium sediments (calcium carbonate and calcium phosphate, generally occur in the second section of the system). The desalination rate drops significantly. The system pressure drop increases. The system water production decreases slightly. Clean the system with solution 1. 2. Oxides (iron, nickel, copper, etc.) The desalination rate is slightly reduced. The system pressure drop is significantly increased. The system water production is significantly reduced. Use solution 1 to clean system 3. Various colloids (iron, organic matter and silica colloids). The desalination rate is slightly reduced. The system pressure drop gradually increases. The system water production volume is gradually reduced. Use solution 2 to clean system 4. Calcium sulfate (generally occurs in the second section of the system) The desalination rate has significantly decreased. The system pressure drop has or moderately increased. The system water production has slightly decreased. Use solution 2 to clean the system 5. Organic matter sedimentation and accumulation. The desalination rate may reduce the system pressure drop and gradually increase. The system water production has slightly decreased. Use solution 2 to clean the system. When the pollution is serious, use solution 3 to clean the system. 6. Bacterial contamination. The desalination rate may decrease. The system pressure drop has increased significantly. The system water production has significantly decreased. According to the possible pollution types, choose one of the three solutions to clean the system. Instructions: The cause of pollution must be confirmed and the source of pollution must be eliminated. If you need help, please contact our company. Table 2 Recommended common cleaning methods. Ingredients of cleaning solution to prepare 100 gallons (379 liters). Amount to be added when preparing the solution. pH adjustment 1. Citric acid 2%. Reverse osmosis product water (no free chlorine) 17.0 pounds (7.7 kg). 100 gallons (379 liters). Use sodium hydroxide to adjust the pH to 4.02. Sodium tripolyphosphate EDTA tetrasodium salt reverse osmosis product water (no free chlorine) 17.0 pounds (7.7 kg). 7 pounds (3.18 kg) 100 gallons (379 liters) Adjusted to pH 10.03 with sulfuric acid Sodium tripolyphosphate Sodium dodecyl benzene sulfonate reverse osmosis product water (no free chlorine) 17.0 pounds (7.7 kg) 2.13 pounds (0.97 kg) 100 gallons (379 liters) Adjusted to pH 10.0 with sulfuric acid