How to use the new RO reverse osmosis membrane correctly?

• Technical points of using the new RO reverse osmosis membrane:
  First, rinse the quartz sand and coconut shell activated carbon, and rinse the newly installed quartz sand and coconut shell activated carbon for a longer time.
  2. Check whether there is residual chlorine, if there is residual chlorine exceeding the standard, solve the residual chlorine problem and then proceed to the next step of RO reverse osmosis membrane.
  3. After the new film is installed, water it and soak the film for 1~2 hours, because it is a dry film, the soaked film is relatively moist to prevent the film from being damaged by too high pressure.
  4. Then start the high-pressure pump, the pressure should be slowly increased, from 2 kg to 8~10 kg, the desalination rate of the new membrane is better.
  5. The residual chlorine is controlled below 0.003.
  6. Open the concentrated water valve before starting the high-pressure pump, and slowly adjust the concentrated water valve after the high-pressure pump is opened to control the recovery rate of a single membrane by about 15%.
  7. The water produced in the first half hour must be drained, because there is a protective liquid in the membrane to avoid affecting the taste of the water.
  8. Detect the PH value of influent water, above 6.5.

• How to judge that the reverse osmosis membrane needs to be cleaned?

Reverse osmosis membrane elements can generally be used for about 2~3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing. Reverse osmosis membrane elements can generally be used for about 2~3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing.

Cleaning of reverse osmosis membranes

As a rule of thumb, if the reverse osmosis unit is cleaned every three months or more. If it is cleaned once every 1-3 months, it is necessary to improve the operating conditions and improve the pretreatment effect.

Judge the cleaning situation:

(1) Standardized freshwater production has decreased by more than 10%.

(2) The standardized salt permeability rate has increased by more than 10%.

(3) In order to maintain the normal flow rate of fresh water, the pressure difference between the feed water and the concentrated water is increased by more than 10% after temperature calibration.

(4) The internal device has serious pollutants and scale.

(5) Before the RO device is deactivated for a long time.

(6) Routine maintenance of RO equipment.

Contaminant

The common pollutants in reverse osmosis membrane elements are mainly CaCO3, CaSO4, BaSO4, SrSO4, metal oxides, silicon deposits, organic matter and biological slime. When the scale inhibitor dosing system or acid addition system fails, CaCO3 may be deposited in the membrane elements, and chemical cleaning should be used for cyclic cleaning or overnight soaking.

Formulation

Different pollutants cause different degrees of damage to the membrane, and different pollutants use different cleaning solutions.

Cleaning equipment

It is generally composed of cleaning pump, chemical preparation box, 5-20um security filter, heater, related pipeline valves and control instruments.

Cleaning methods include static soaking and cyclic cleaning. Static soaking is soaked in cleaning liquid, and the time is approximately 1-15h depending on the degree of pollution. The general steps of cyclic cleaning are:

1. Pump fresh water from the preparation box into a pressure vessel and discharge it for a few minutes.

2. Prepare the cleaning solution with fresh water in the preparation box.

3. Cycle the pressure vessel with cleaning liquid for 1 hour or reach the predetermined time. The cleaning flow rate can be determined according to the table below, and when the contamination is severe, the cleaning flow can be increased to 150% of the resin in the table. At this time, the cleaning pressure drop is large, and the general control is not more than (0.10-0.14MPa)/root film element or 0.4MPa/root film assembly. At the beginning of the cleaning of the medicine, 50% of the flow value in the meter can be used to pour the heated cleaning solution into the pressure vessel to control the pressure, so that it can overcome the pressure drop between the inlet and the outlet water 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 from 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 film roll to bulge and damage the film elements.

4. After the cycle cleaning is completed, wash the preparation box with fresh water.

5. 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, foam-free, or free of cleaning fluid, which usually takes 15-30 minutes.

Reverse osmosis membrane replacement

After the normal operation of the reverse osmosis equipment for a period of time, the reverse osmosis membrane elements will be contaminated by suspended solids or insoluble salts that may be present in the feed water, and the following symptoms will appear:

1. The weight of the membrane elements of the reverse osmosis equipment has increased;
2. The RO membrane removal rate increased or decreased significantly;
3. Under standard pressure, the water yield of reverse osmosis equipment decreased significantly.
4. In order to achieve the standard water yield, the operating pressure needs to be improved;
5. The pressure drop between the influent water and the concentrated water of the reverse osmosis equipment increases;
6. Take the membrane element out of the pressure vessel, pour water on the inlet side of the upright membrane element, if the water cannot flow through the membrane element, only overflow from the end face, indicating that the inlet flow channel is blocked.