Treatment method for RO reverse osmosis membrane performance degradation

The main reason for the decline in the performance of general RO reverse osmosis membranes is due to contamination of the membrane surface, such as surface fouling, clogging of membrane pores or due to physicochemical changes. The physical change is due to the compaction effect causing the permeability of the reverse osmosis membrane to decrease. Chemical changes are mainly caused by fluctuations in pH, such as hydrolysis of cellulose acetate membranes, and free chlorine also degrades the performance of the oriented polyamide membrane. The clogging of the reverse osmosis membrane pores is mainly caused by the deposition of membrane surface area and the growth of microorganisms. Among them, microorganisms not only block the pores of the membrane, but also have an effect of eroding damage to cellulose acetate.
A certain amount of residual chlorine must be maintained in the RO reverse osmosis membrane 0.1~0.5mg/L. The cleaning treatment of the RO reverse osmosis membrane is a subtle and cumbersome work. At present, the quality of the domestic membrane is not high enough, and the multi-clean membrane is easily damaged. In order to alleviate the cleaning work, it is necessary to do a good job of pre-treatment, and strictly control the water quality, otherwise it will be "endless."
The RO reverse osmosis membrane treatment method is: periodically circulating and treating with a 0.1% formaldehyde solution for at least one hour. The contaminated membrane should be cleaned with 2% ammonium citrate solution (pH=4~8) or with sodium bisulfite, sodium hexametaphosphate or dilute hydrochloric acid to prevent scaling of manganese, iron and carbonate. Organic substances are sometimes washed with an enzyme detergent. The cleaning pressure is 0.34~0.98MPa (3.5~10kgf/cm2), and the cleaning flow rate is 2~3 times of the original water treatment flow rate.
How to debug daily reverse osmosis equipment
The reverse osmosis equipment is divided into two parts, one part is pretreatment debugging, and the other part is the reverse osmosis host debugging part. The pretreatment is mainly positive and negative washing quartz sand, activated carbon, so that fine sand charcoal and impurities are washed away, and the amount of water entering the water is controlled. Infiltration host debugging is mainly to adjust the flow of water, water flow and pressure, the following is how to debug the daily reverse osmosis equipment?
1. Analyze and test the water inflow of the device. The results show that the water supply requirements can be adjusted before the water supply is adjusted.
2. Adjust the pressure control system of the high pressure pump.
3. Check whether the connection between all the pipes is perfect, whether the pressure gauge is complete, whether the low-pressure pipe connection is tight, and whether there is a shortage.
4. Open a pressure gauge switch and total inlet valve, concentrated water discharge valve, and water discharge valve.
5. Start the pretreatment equipment and adjust the water supply to be larger than the total water intake of the device.
6. Backwash and wash the charcoal filter until the water is clear.
7. Start the high pressure pump and slowly open the total inlet valve of the device. The total inlet pressure of the control unit is less than 0.5Mpa, flush for 5 minutes, and check whether the high and low pressure pipelines and instruments are normal.
8. Adjust the inlet valve and the concentrated water discharge valve to make the inlet pressure reach 1.0~1.4Mpa.
9. Detect the water conductivity of the product, open the product outlet water valve when the requirements are met, and close the production water discharge valve.
10. The debugging of the RO device is a manual single-step Cao group. After the operation is normal, it can be switched to the automatic state, and the online instrument and PLC automatically control the operation.
11. Start the regeneration system and see if the regeneration system is working properly.
The most important thing to note about reverse osmosis debugging is to remember that the water valve is closed and the high pressure pump is turned on. This will cause great damage. Therefore, when debugging, be sure to pay attention to whether the pipeline is in the same state to start the pump.
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