1、 Preparation principle

Reverse osmosis water treatment equipment is usually composed of raw water pretreatment system, reverse osmosis purification system and ultra purification post-treatment system. The main purpose of pretreatment is to make the raw water meet the requirements of reverse osmosis membrane separation module and ensure the stable operation of reverse osmosis purification system. Reverse osmosis membrane system is the most economical and efficient purification method to remove more than 98% ions, organics and 100% microorganisms in raw water. The ultra purification post-treatment system can further remove trace ions, organic matter and other impurities in RO pure water through a variety of integrated technologies, so as to meet the final water quality requirements for different purposes.

2、 How it works

Reverse osmosis (RO) is the most precise membrane liquid separation technology. The operating pressure is applied on the inlet (concentrated solution) side to overcome the natural osmotic pressure. When the operating pressure higher than the natural osmotic pressure is applied on the concentrated solution side, the flow direction of water molecules' natural osmosis will be reversed, and the water molecules in the inlet (concentrated solution) will become the purified water on the dilute solution side through the RO membrane; Reverse osmosis equipment can block all dissolved salts and organic matters with molecular weight greater than 100, but it allows water molecules to pass through. The desalination rate of reverse osmosis composite membrane is generally greater than 98%. They are widely used in the preparation of industrial pure water and electronic ultra pure water, the production of drinking pure water, boiler feed water and other processes. Using reverse osmosis equipment before ion exchange can greatly reduce the discharge of operating water and wastewater.

3、 Pretreatment system introduction reverse osmosis water treatment system generally includes pretreatment system, reverse osmosis device, after treatment system, cleaning system and electrical control system. Pretreatment system generally includes quartz sand filter, activated carbon filter, precision filter, etc. Its main function is to reduce the pollution index of raw water and other impurities such as residual chlorine to meet the requirements of reverse osmosis. Detailed classification of pretreatment system: 1. Quartz sand filter quartz sand filter mainly removes suspended solids, colloid, sediment, clay, saprophyte, particulate matter and other impurities in water. It can reduce the turbidity of water, achieve the purpose of water quality clarification and protect the reverse osmosis membrane. 2. Activated carbon filter activated carbon filter mainly uses a large number of hydroxyl (hydroxyl) and hydroxyl and other functional groups on the surface of activated carbon to carry out chemical adsorption on various substances, remove the peculiar smell, organic matter, colloid, iron and residual chlorine in water, reduce the chroma and turbidity of water, and reduce the pollution to reverse osmosis system. 3. The softener uses sodium ion on the ion exchange resin to exchange calcium and magnesium ions in water to reduce the hardness of water. At the same time, the softener uses soft water salt to regenerate the ion exchange resin. Soft water salt is also known as regeneration agent of ion exchange resin. 4. Precision filter

The 5 micron PP melt blown filter core is mainly used to remove the particles larger than 5 microns that are not removed by the pretreatment system, and intercept the filter material lost in the first three filtration procedures, so as to protect the RO membrane.

Whether the filter element can meet the normal use conditions will affect the normal working conditions of the membrane. Generally, the filter element is replaced every 3-4 months.

4、 Introduction of reverse osmosis system

The reverse osmosis system mainly consists of multi-stage high pressure pump, reverse osmosis membrane element, membrane shell (pressure vessel), support, etc. Its main function is to remove the impurities in the water and make the effluent meet the use requirements. The high-pressure pump will boost the outlet water of the security filter to the working pressure of RO, and then evenly distribute it to the pressure vessel. The water flow is separated by the reverse osmosis membrane, and two water flows are formed in the pressure vessel. Part of the influent water passes through the membrane to form pure water, while the remaining inorganic salts and solid residues are detained and concentrated to form concentrated water, thus realizing the separation of inorganic salts and water.

The purified water flows out from each pressure vessel equipped with reverse osmosis membrane and flows through the flowmeter after confluence, then flows out of the outlet of the equipment and enters the pure water tank, while the concentrated water flows out from the concentrated outlet of the pressure vessel.

Desalination mechanism of reverse osmosis membrane: there are many very thin membrane pores on the surface of the semi permeable membrane. A layer of water molecules are selectively adsorbed on the surface of the membrane, and salt solutes are repelled by the membrane. The higher the valence state of ions is repelled, the farther away they are repelled. Under the push of reverse osmosis pressure, the water molecules around the membrane pores flow out pure water through the capillary action of the membrane to achieve the purpose of desalination.

When the pore size of the membrane is larger than that of the reverse osmosis membrane, the water solution of salt will leak through the membrane, and the divalent salt will leak more, followed by the divalent salt, and the trivalent salt will leak less. The pore size of RO membrane was less than 1.0 nm, so the RO membrane could remove one of the least bacteria, Pseudomonas aeruginosa (3000 nm) × 10-10m)； Can also filter out a variety of viruses, such as influenza virus (800 × 10-10m), meningitis virus (200 × 10-10m)； It can even filter out heat sources (10-500) × 10-10m)。 The characteristics of the preparation of pure water by reverse osmosis are as follows: compact equipment structure, simple maintenance, small floor area and high water yield; The preparation of pure water without phase transition has low energy consumption; At the same time, there is no acid, alkali and other wastewater discharge, which is a new energy-saving environmental protection equipment;

The ratio of wastewater and pure water in reverse osmosis system is usually 3:1 for small domestic water purifiers, 1:1 for small industrial reverse osmosis system and 0.3:0.7 for large-scale system. If we want to reduce wastewater discharge, the cost will be higher and the service life of reverse osmosis membrane will be shortened.

This advanced membrane separation technology has been widely used in various fields  。 5、 Reverse osmosis system maintenance 1. Do a good job in daily water quality testing and equipment operation parameters recording work, find abnormal timely solution. The conductivity of pure water, the pressure of each point and the flow rate of inlet and outlet water were detected and recorded regularly every day. 2. Add regenerant to the salt tank regularly, and set the regeneration time according to the actual situation and water yield. It is usually added once every 3-4 days. 3. Replace the security filter element in time（ 4. Wipe the machine frequently to keep the equipment clean. 5. Regularly check whether there is water leakage in the pipeline and solve it in time.

6. The normal water and power supply of the equipment should be ensured. In case of power failure and water cut, the time of the equipment should be readjusted, especially the regeneration time after power failure. It is forbidden for irrelevant personnel to touch the button of the electric control part and the valve of the pipeline part, so as to prevent the equipment from being used normally due to misoperation.

6、 In case of power failure of emergency equipment or damage of pure water components such as main pump and membrane, the softened water valve can be opened to continue to use the softened water to ensure the normal operation of water equipment. This method shall be based on the actual requirements of water equipment. 1. When the water leakage of the equipment is serious, the water inlet switch of the equipment shall be turned off immediately, and the power supply shall be turned off, and the service provider shall be informed to deal with it.

2. In the process of water production, when the pressure gauge behind the membrane shows more than 1.5MPa, the conductivity exceeds 15US / cm or the water quality exceeds the standard range, the resin, membrane, activated carbon and other consumables should be replaced in time.

7、 The change of consumables indicates that the quartz sand, activated carbon and softening resin are granular objects, which are easy to form a porous structure after accumulation, providing a growth environment for the long-term propagation of fungi. At the same time, activated carbon and softening resin adsorption have a certain degree of saturation, and the filtration effect will decline after long-term use. When the washing regeneration can not meet the pretreatment effect, it can be replaced to ensure the water quality of reverse osmosis membrane.

Under all conditions, the service life of quartz sand, activated carbon, resin, precision filter element and reverse osmosis membrane is 10-24 months, 10-12 months, 3-6 months and 12 months respectively.           Resin regeneration cycle: under normal conditions, the resin regeneration cycle is 1-3 days.

8、 Application fields 1. Power industry: boiler make-up water, cooling dam; 2. Electronic industry: semiconductor industry ultra pure water, integrated circuit cleaning water, formula water; 3. Food industry: formula water, production water; 4. Pharmaceutical industry: process water, preparation water, washing water, injection water, sterile water preparation; 5. Beverage industry: formula water, production water, washing water; 6. Chemical industry: production water, wastewater treatment; 7. Drinking water engineering: ultra pure water preparation, drinking water purification; 8. Petrochemical Industry: advanced treatment of oilfield injection water and petrochemical wastewater; 9. Seawater desalination: water for production and living in island areas, coastal water shortage areas, ships, sea water oil fields, etc;

10. Environmental protection field: recovery of precious metals and water in electroplating rinsing water to achieve zero or micro discharge.