How to debug a reverse osmosis pure water equipment?

Before commissioning the reverse osmosis pure water equipment, confirm that all power connections are intact, the pretreatment equipment has been commissioned, and the effluent meets the reverse osmosis membrane feed water requirements. Before the initial start-up of the reverse osmosis unit, the pretreatment system of the raw water must have been debugged and trial-run, and the effluent quality must meet the reverse osmosis unit feed water requirements. After secondary filtration, the turbidity of the water should be <1.0NTU and SDI<5.0.

1. Water supply conditions that must be confirmed before supplying pretreatment water to membrane elements

Water temperature 30~40℃; pH value within the range specified in the specifications and performance table of each reverse osmosis membrane element; FI value and monthly average below 3.0, maximum allowable value below 5.0; residual free chlorine 0.1~0.7mg/L (hollow fiber membrane), not detected (polyamide composite membrane).

2. Other conditions of the supply water

① It does not contain substances that will reduce membrane performance, such as residual free chlorine (allowable range for SC series), and oxidizing substances such as peroxides and ozone.

② It does not contain substances that will adhere to the membrane surface and cause a reduction in water volume (such as styrene, ethane extracted oil, etc.).

③ Substances that cannot be removed with approved chemicals, such as SiO2, CaSO4, BaSO4, SrSO4, CaF2, etc., cannot exceed their precipitation critical values. When exceeding the critical value, the specified antiscalant should be used.

④ It does not contain substances that will adsorb, react, or swell on the membrane element and membrane material, causing changes in the performance of the membrane element.

⑤ It does not contain organic solutions that undergo phase separation on the membrane surface.

⑥ Sterilization treatment should be carried out regularly to inhibit microorganisms in the pretreatment equipment, including the water intake equipment.

3. Verification of the water supply chemical dosing system

① All pipes and equipment must be made of corrosion-resistant materials and have been thoroughly rinsed.

② The added chemicals must be compatible with each other and have no adverse effects on the reverse osmosis membrane.

③ Ensure that the chemicals are fully mixed with the feed water.

4. Inspection of the reverse osmosis pure water equipment

① Check that the 5μm safety filter can effectively protect the high-pressure pump and reverse osmosis membrane elements.

② Check that the pressure gauge, flow meter, conductivity meter, etc., are correctly installed and calibrated.

③ Check that representative water samples can be taken from each section of feed water, each section of product water, and total concentrate water, and total product water.

④ Verify that the interlocks and alarms have been correctly set.

⑤ Verify that the product water pipeline is indeed open. Ensure that the concentrate water flow control valve is in the open position, and manually adjust the opening if necessary.

⑥ During operation, supervise that various chemicals, reagents, and analytical instruments (pH meter) used in the laboratory are fully equipped.

5. Debugging steps

① Rinse the reverse osmosis pressure vessel and related components of the reverse osmosis unit with low-pressure water flow.

② Remove the two end plates of the pressure vessel.

③ Remove the membrane element from the sealed plastic bag and push it into the pressure vessel in the direction of water flow. Glycerin should be applied to the sealing rings on both sides of the membrane element and pressure vessel as a lubricant. The concentrate water seal of the element should be located upstream.

④ Rinse the membrane element with water that meets the feed water requirements of the reverse osmosis unit (without antiscalant). The rinsing should be carried out according to the requirements of the membrane manufacturer's data.