With the rapid development of electronic components and biotechnology, sewage treatment is also constantly improving in practical applications, especially with the detailed theoretical foundation of membrane treatment, which has been tested by long-term social practice activities. RO reverse osmosis system is a crucial operating procedure in wastewater treatment, characterized by meticulous mechanical equipment and high operating pressure. The operation of the system will immediately affect the quality of the final effluent, so it seems particularly important to do a good job in adjusting the RO reverse osmosis system. We can grasp from the following aspects:

1、 Operational specifications

The RO reverse osmosis system consists of an RO membrane, a high-pressure pump, and a multi substance filtration device set up for maintenance of the RO membrane. The multi substance filtration device is equipped with a filtration diameter of 5 μ M filter element. This type of filter element will filter out all specifications and models exceeding 5 μ M particles. It has maintenance and upkeep functions for the RO membrane in the middle and upper reaches, otherwise the surface of the RO membrane is prone to scaling. At present, the most common type of membrane penetrated is acrylic emulsion liquid membrane, and the membrane mode is roll composite packaging bag. The desalination rate of this type of membrane is 99.5%. Due to the susceptibility of RO membranes to damage from pH, permanganate index, and temperature in water, there are strict requirements for the leakage water quality before RO membrane operation:

PH value: 3-10

Permanganate index:< 0mg/L

SDI15 value:< five

Temperature:< 45 ℃

Exceeding any of the above indicators may cause infiltration into the membrane and cause deformation, thereby damaging the effluent quality and reducing the service life of the membrane. And the types of membranes also have different requirements for leakage water quality. Before adjustment, it can be clarified according to the instructions provided by the RO film manufacturer.

2、 Adequate preparation before operation

As a high-pressure operating mechanical equipment, RO should strictly follow the operation steps to clarify and adjust the opening status of the shut-off valve for maintenance of the mechanical equipment and the instrument panel inside the vehicle and safety reasons before operation. The operation steps are as follows:

1. Fully open the water gate valve of the multi material filtration device and open the water gate valve of the high-pressure pump

2. Open the high-pressure pump outlet shut-off valve one circle

3. Open the RO inlet valve one turn

4. Rotate the needle valve on the concentrated water pipe three and a half turns

5. Fully open the inlet and outlet valves of the produced water and the inlet and outlet valves of the concentrated water

6. Close all sampling valves and clear shut-off valves

7. Open all pressure display valves to a semi closed position

3、 Trial operation

When all the above specifications are clearly considered, the high-pressure pump fund allocation trial operation can be initiated. As RO is also a liquid screening machine equipment, water can only rely on RO reverse osmosis membrane when the water supply and drainage pressure is higher than the infiltration concentration value, thereby ensuring the expected desalination effect. The driving force for this situation comes from the pressure difference between the water supply and drainage (concentrated water) and the infiltration concentration value (the infiltration concentration value varies with the type and method of infiltration into the membrane) in the middle（ Δ P) , this part of the Δ P can be adjusted and controlled by a shut-off valve (valve 5) installed at the RO inlet and a pressure regulating needle valve (valve 13) installed on the concentrated water pipeline. At the beginning, the total leakage output value (the sum of readings from steam flow meters 11 and 12) was adjusted to the designed inlet and outlet water volume based on the RO inlet shut-off valve. Next, use a pressure regulating needle valve (valve 13) to accurately adjust the output water volume and concentrated water pressure. When the water production rate is lower than the design value of the plan, it indicates that the pressure of water supply and drainage (concentrated water) is not high, which is Δ The P value is not high, so the needle valve should be adjusted down at this moment to expand the pressure of concentrated water (leakage) until the water production rate is equal to the design value of the plan.

4、 Common problem analysis

High pressure pump found abnormal shutdown

1) Pump leakage pressure below 0.05Mpa

2) Concentrated water pressure exceeding 1.4Cpa

3) The water production pressure is higher than 0.5CPa

1) Increase the pressure of upstream, midstream, and downstream treated water;

2) According to the RO inlet shut-off valve

Adjust the needle valve on the concentrated water pipe

Concentrated water pressure

3) Using the same method as 2) to solve the problem

Insufficient water output

1) Insufficient inflow and outflow of water

2) Insufficient concentrated water pressure, i.e. insufficient leakage pressure

1) Install the high-pressure pump inlet and outlet shut-off valves and

RO inlet shut-off valve enlarged

2) Reduce the needle valve on the concentrated water pipeline

Excessive water output

1) Excessive inflow and outflow of water

2) Excessive concentrated water pressure, i.e. excessive leakage pressure

1) Install the high-pressure pump inlet and outlet shut-off valves and

Reduce the RO inlet shut-off valve

2) Enlarge the needle valve on the concentrated water pipeline

Abnormal sound found in high-pressure pump

1) Poor contact condition of motor drive roller bearings

2) Due to the low leakage pressure of the pump, cavitation occurs

1) Maintenance of rotating rolling bearings

2) Increase the treatment water pressure in the upstream, midstream, and downstream sections

If the adjustment of the RO reverse osmosis system is carried out according to the operation steps of scientific research, and the pre adjustment inspection is carefully carried out, this part of the work can be done well.

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