[Required for work] Main points for installation of dual-stage reverse osmosis water treatment equipment

Ⅰ. Process description
The raw water is well water with high suspended matter content and high hardness. In order to make the influent meet the reverse osmosis influent requirements, a machine filter is set up, which contains fine quartz sand, which can remove suspended solids and sediment in the water. Adding scale inhibitor system can add scale inhibitor at any time to reduce the scaling tendency of hardness ions in water and prevent concentrated water structure. The precision filter contains a honeycomb spiral wound filter element with an accuracy of 5 microns, which further removes hard particles in the water and prevents scratching of the membrane surface. The reverse osmosis device is the core desalination part of the equipment. The single-stage reverse osmosis can remove 98% of the salt ions in the water.

Ⅱ. Mechanical filter operation
1. Exhaust: Open the upper exhaust valve and the upper intake valve to send water into the filter to the upper exhaust valve for continuous water intake.
2. Washing: Open the lower discharge valve and the upper inlet valve to allow water to pass through the filter layer from top to bottom, and the inlet water flow rate is 10t / h. It takes about 10-20 minutes until the drainage is clear and transparent.
3. Operation: Open the water outlet valve to send water to the subsequent equipment.
4. Backwashing: After running for a period of time, the filter cake is formed on the surface due to dirt retention. When the pressure difference between the inlet and outlet of the filter is greater than 0.05-0.08MPa, backwashing should be performed to ensure smooth water flow. Open the upper discharge valve, backwash valve, bypass valve, and flush at a flow rate of 10t / h for about 20-30 minutes until the water is clear. Note: After backwashing, the equipment must be washed before it can be put into operation.

Ⅲ. softener switch cleaning
The working principle of the softener is ion exchange. The characteristic of the ion exchanger is that the resin must be regenerated frequently. Pay attention to the following issues when using:
1. When the hardness of the effluent water exceeds the standard (hardness requirement ≤0.03mmol / L), it must be stopped and regenerated;
2. The regeneration method of cationic resin is to soak the resin in saline for about two hours, let the salt water dry, and then backflush it with water to continue using it;

Ⅳ. Add scale inhibitor system
The metering pump and the high-pressure pump start and stop at the same time and act synchronously. The scale inhibitor is MDC150 made in the United States. Dosage of scale inhibitor: According to the hardness of raw water, it is calculated that the dosage of 3-4 grams per ton of raw water. The system water intake is 10t / h, then the dosage per hour is 30-40 grams.
Configuration of scale inhibitor: Add 90 liters of water to the medicine box, then slowly add 10 kg of scale inhibitor, mix well. Adjust the measuring pump range to the corresponding scale.
Note: The minimum concentration of scale inhibitor should not be less than 10%.

Ⅴ. Precision filter
The precision of the precision filter is 5μm. To maintain the precision of the filter, the system does not have a backwashing line. The filter element in the precision filter usually lasts 2-3 months, and it can be extended to 5-6 months according to the actual water treatment. Sometimes the filter element can be replaced in advance to maintain the water flux.

Ⅵ. Reverse osmosis cleaning
Due to the accumulation of impurities in the water for a long period of time, the reverse osmosis membrane element is prone to scaling and leads to a decrease in water production and a reduction in the desalination rate. At this time, the membrane element needs to be chemically cleaned.
When the equipment has one of the following conditions, it must be cleaned:

1. Under normal pressure, the product water flow drops to 10-15% of the normal value;
2. In order to maintain normal product water flow, the feed water pressure after temperature correction is increased by 10-15%;
3. The product water quality is reduced by 10-15%; the salt permeability is increased by 10-15%;
4. The operating pressure increases by 10-15%; 5. The pressure difference between RO sections increases significantly.

Ⅶ.the preservation method of the membrane element:

1. Short-term preservation
It is suitable for reverse osmosis systems that have stopped running for 5-30 days. At this time, the membrane element is still installed in the pressure vessel of the system.

(1) Flush the reverse osmosis system with feed water, and pay attention to completely remove the gas from the system;
(2) After filling the pressure vessel and related pipelines with water, close the related valves to prevent gas from entering the system;
(3) Flush once every 5 days according to the above method.

2. Long-term shutdown protection
(1) Cleaning the membrane elements in the system;
(2) Prepare the sterilizing liquid with the reverse osmosis produced water, and flush the reverse osmosis system with the sterilizing liquid;
(3) After filling the reverse osmosis system with the sterilizing liquid, close the relevant valves to keep the sterilizing liquid in the system. At this time, make sure that the system is fully filled;
(4) If the system temperature is lower than 27 degrees, it should be operated with new sterilization liquid every 30 days; if the temperature is higher than 27 degrees, the sterilization liquid should be replaced every 15 days;
(5) Before the reverse osmosis system is put back into use, flush the system with low-pressure feed water for one hour, and then flush the system with high-pressure feed water for 5-10 minutes; regardless of low-pressure flushing or high-pressure flushing, the system’s product water discharge valve should be fully opened. Before the system resumes normal operation, it should be checked and confirmed that the product water does not contain any fungicides.