The key technical points for using a new RO reverse osmosis membrane are: 1. First, rinse the quartz sand and coconut shell activated carbon clean. Rinse the newly installed quartz sand and coconut shell activated carbon for a longer period of time. 2. Check for residual chlorine. If there is excessive residual chlorine, solve the problem before proceeding with the next step of RO reverse osmosis membrane work. 3. After installing the new membrane, rinse it with water and soak it for 1-2 hours. As it is a dry membrane, the soaked membrane is relatively moist to prevent damage from high pressure. 4. Then start the high-pressure pump, and the pressure should gradually increase from 2 kilograms to 8-10 kilograms for better desalination efficiency of the new membrane. 5. The residual chlorine should be controlled below 0.003. 6. Before starting the high-pressure pump, open the concentrated water valve first. After the high-pressure pump is turned on, slowly adjust the concentrated water valve to control the recovery rate of a single membrane to about 15%. 7. The water produced in the first half hour must be drained because there is a protective solution inside the membrane to avoid affecting the taste of the water. 8. Detect the pH value of the incoming water, which is above 6.5. 2、 How to determine if the reverse osmosis membrane needs to be cleaned? Introduction
Reverse osmosis membrane components can generally be used for about 2-3 years. If you want to extend the service life, you can clean the reverse osmosis membrane components, usually divided into two methods: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be carried out. Reverse osmosis membrane components can generally be used for about 2-3 years. If you want to extend the service life, you can clean the reverse osmosis membrane components, usually divided into two methods: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be carried out.
Cleaning of reverse osmosis membrane
Based on experience, if the reverse osmosis device is cleaned every three months or longer. If it is cleaned once every 1-3 months, it is necessary to improve the operating conditions and enhance the pre-treatment effect.
1. Determine the cleaning situation:
(1) Standardized freshwater production has decreased by over 10%.
(2) The standardized salt penetration rate has increased by more than 10%. (3) In order to maintain normal freshwater flow, the pressure difference between the feedwater and concentrate has increased by more than 10% after temperature calibration. (4) The internal device has serious pollutants and scaling. (5) Before the long-term shutdown of the RO device. (6) Routine maintenance of RO device. Before determining whether to clean the reverse osmosis system, other possible reasons that may cause the above phenomenon should also be considered comprehensively: ☆ Decrease in operating pressure (failure of pressure control device and abnormality of high-pressure pump); ☆ Decreased inlet water temperature (due to heater malfunction or seasonal changes causing a decrease in water temperature); ☆ The salt content in the incoming water increases; ☆ Preprocess exceptions; Due to membrane damage, misalignment of the central tube of the series membrane element, and inadequate sealing of the pressure vessel O-ring, concentrated water seeps into fresh water. The common pollutants in reverse osmosis membrane components include CaCO3 CaSO4、BaSO4、SrSO4、 Metal oxides, silicon deposits, organic matter, and biofouling. When the scale inhibitor dosing system or acid dosing system malfunctions, CaCO3 may deposit in the membrane components, and chemical cleaning methods should be used for cyclic cleaning or overnight soaking.
3 formulas
Different pollutants cause varying degrees of damage to the membrane, and different cleaning solutions should be used for different pollutants.
4 Cleaning equipment
(1) Reverse osmosis cleaning system
It generally consists of a cleaning pump, a chemical preparation box, a 5-20um security filter, a heater, related pipeline valves, and control instruments.
(2) The cleaning methods include static soaking and cyclic cleaning. Soak the membrane in cleaning solution for static immersion, with a duration of approximately 1-15 hours depending on the degree of contamination. The general steps of cyclic cleaning are: 1. Use a pump to transfer fresh water from the chemical preparation tank into the pressure vessel and discharge for a few minutes. Prepare cleaning solution with fresh water in the medication preparation box. 3. Use cleaning solution to cycle and clean the pressure vessel for 1 hour or until the predetermined time is reached. The cleaning flow rate can be determined according to the table below. When the pollution is severe, the cleaning flow rate can be increased to 150% of the resin in the table. At this point, the pressure drop during cleaning is relatively high, generally controlled not to exceed (0.10-0.14MPa) per membrane element or 0.4MPa per membrane module. At the beginning of drug cleaning, 50% of the flow rate value in the table can be used to inject the heated cleaning solution into the pressure vessel and control the pressure to overcome the pressure drop between inlet and outlet without fresh water flowing out. To avoid dilution of the cleaning solution, the concentrated water discharge valve can be opened to drain the accumulated water in the system before cleaning. The reverse osmosis system can be cleaned in sections. The cleaning direction is the same as the running direction, and reverse cleaning is not allowed, otherwise it may cause the membrane roll to protrude and damage the membrane element. After completing the 4-cycle cleaning, clean the chemical preparation box with fresh water. Rinse the pressure vessel with fresh water.
6 After flushing, run the reverse osmosis system with the fresh water discharge valve open until the fresh water is clean and there is no foam or cleaning solution, which usually takes 15-30min.
Replacement of reverse osmosis membrane
After a period of normal operation of reverse osmosis equipment, the reverse osmosis membrane elements may be contaminated by suspended solids or insoluble salts that may exist in the feedwater, resulting in the following symptoms: 1. The weight of the reverse osmosis equipment membrane elements increases; The removal rate of 2RO membrane significantly increases or decreases; Under 3 standard pressures, the water production of reverse osmosis equipment significantly decreases; In order to achieve the standard water production, it is necessary to improve the operating pressure; The pressure drop between the inlet water and concentrated water of the reverse osmosis equipment increases; Remove the membrane element from the pressure vessel and pour water onto the inlet side of the upright membrane element. If water cannot flow through the membrane element and only overflows from the end face, it indicates that the inlet channel is blocked.
Whether to replace the reverse osmosis membrane components or not depends on the actual situation.
