1Introduction

　　Reverse osmosis equipment processes raw water through fine filters, granular activated carbon filters, compressed activated carbon filters, etc,Then increase the pressure through a pump,The aperture is utilized as1/10000μm(Equivalent to the size of Escherichia coli1/6000,"Virus 1/300)Reverse osmosis membranes(ROmembrane),Separate water with a higher concentration into water with an extremely low concentration (that is, purified water) and water with an even higher concentration. Use the water with a lower concentration and discharge or reuse the water with a higher concentration. At the same time, isolate all impurities such as industrial pollutants, heavy metals, and viruses that are mixed in large quantities in the water, so as to meet the physical and chemical indicators and hygiene standards for drinking water,Produce pure water,It is a good choice for the human body to replenish good water in a timely manner.BecauseROThe purity of water produced by reverse osmosis technology is among the highest among the water production technologies currently mastered by humans in the field of drinking water manufacturing,So people call this water-producing machine a reverse osmosis pure water machine. Of course, there are also some even higher-purity pure water manufacturing technologies (such asEDIPolishing mixed beds, etc., are not suitable for drinking water production.

　　Pure water equipment, simply put, is the equipment used to produce pure water. Pure water is widely used by us in: daily drinking, chemical industry, breeding, planting, beverages, etc.

　　Reverse osmosis equipment, applying membrane separation technology, can effectively remove charged ions, inorganic substances, colloidal particles, and organic matter from water. It is an excellent device in the processes of high-purity water preparation, brackish water desalination and wastewater treatment. It is widely used in fields such as electronics, medicine, light textile, chemical engineering, and power generation.

　　Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that uses pressure difference as the driving force to separate the solvent from the solution. When pressure is applied to the feed liquid on one side of the membrane and exceeds its osmotic pressure, the solvent will undergo reverse osmosis in the opposite direction of natural osmosis. Thus, the solvent that passes through, namely the permeate, is obtained on the low-pressure side of the membrane. The concentrated solution, namely the concentrate, is obtained on the high-pressure side. If reverse osmosis is used to treat seawater, fresh water is obtained on the low-pressure side of the membrane and brine on the high-pressure side.

　　During reverse osmosis, the permeation rate of the solvent is the liquid flowNFor:

　　N=Kh(Δp－Δπ)

　　In the formulaKhIt is the hydraulic permeability coefficient, which slightly increases with the rise in temperature.ΔpIt is the static pressure difference on both sides of the membrane;ΔπIt is the osmotic pressure difference of the solutions on both sides of the membrane. The osmotic pressure of a dilute solutionπFor:

　　π=iCRT

　　In the formulaiThe number of ions generated by the ionization of solute molecules;CIs the molar concentration of the solute;RIs the molar gas constant;TFor temperature.

　　Reverse osmosis typically employs asymmetric membranes and composite membranes. The equipment used in reverse osmosis mainly consists of hollow fiber or spiral wound membrane separation devices.

　　Reverse osmosis membranes can retain various inorganic ions, colloidal substances and macromolecular solutes in water, thereby obtaining purified water. It can also be used for the pre-concentration of large-molecule organic solution. Due to the simplicity of the reverse osmosis process, low energy consumption and proximity20It has developed rapidly over the years. It has now been widely applied in seawater and brackish water (see brine) desalination, boiler water softening and wastewater treatment, and combined with ion exchange to produce high-purity water. Its application scope is expanding and has begun to be used in the concentration of dairy products and fruit juices, as well as in the separation and concentration of biochemical and biological preparations.

　　2The system composition of reverse osmosis pure water equipment

　　A reverse osmosis pure water treatment system generally includes a pretreatment system, reverse osmosis device, post-treatment system, cleaning system and electrical control system, etc. 　The pretreatment system generally includes raw water pumps, dosing devices, quartz sand filters, activated carbon filters, precision filters, etc. Its main function is to reduce the pollution index and residual chlorine and other impurities of the raw water, meeting the feed water requirements for reverse osmosis. 　The reverse osmosis device mainly consists of multi-stage high-pressure pumps, reverse osmosis membrane elements, membrane housings (pressure vessels), supports, etc. Its main function is to remove impurities from water to ensure that the effluent meets the usage requirements.

　　The post-treatment system is an additional configuration when reverse osmosis fails to meet the effluent requirements. It mainly includes one or more of the following equipment: anion bed, cation bed, mixed bed, ultrafiltration, etc.

　　The cleaning system mainly consists of a cleaning water tank, a cleaning water pump and a precision filter. When the reverse osmosis system is contaminated and the effluent indicators fail to meet the requirements, it is necessary to clean the reverse osmosis system to restore its effectiveness.

　　The electrical control system is used to control the normal operation of the entire reverse osmosis system. Including instrument panels, control panels, various electrical protections, electrical control cabinets, etc.

　　3The characteristics of reverse osmosis devices

　　1.The reverse osmosis membrane is an imported spiral wound composite membrane. Membrane material: Aromatic polyamide.

　　2.It has a large water permeability and a high desalination rate. Under normal circumstances≥98%

　　3.It has a very high retention and removal effect on organic matter, colloids, particles, viruses, pyrogens, etc.

　　4.It has low energy consumption, high water utilization rate and lower operating costs than other desalination equipment.

　　5.The separation process involves no phase change and has reliable stability.

　　6.The equipment is compact in size, easy to operate and maintain, highly adaptable and has a long service life.

　　4The design features of reverse osmosis pure water equipment

　　1Deep filtration of water is achieved by increasing the pressure on the water. In addition to the common filters, reverse osmosis pure water equipment also includes fine filters, granular activated carbon filters and compressed activated carbon filters. Fine filters have a more refined filtration function than ordinary filters and can better filter impurities in water. As we all know, activated carbon has a good adsorption and filtration function for odors and impurities. The reverse osmosis pure water equipment uses dual activated carbon filters to achieve deep filtration processing of raw water, improving the filtration efficiency of the equipment. At the same time, enhancing the filtration capacity by increasing the water pressure is also an innovation.

　　2The core of reverse osmosis pure water equipment lies in the application of reverse osmosis membranes. Reverse osmosis membranes are a type of filtration membrane with extremely small pores. By using this membrane, ultra-fine filtration of raw water can be achieved, and water can be divided into higher and lower concentrations at the same time. Water with a higher concentration can be recycled and reused, while water with a lower concentration is pure water and can be used by people.

　　5Cleaning method

　　Reverse osmosis technology has been increasingly widely applied due to its unique superiority. The cleaning issue of reverse osmosis water purification equipment may cause losses to many users with weak technical capabilities. Therefore, by doing a good job in the management of reverse osmosis equipment, serious problems can be avoided.

　　Low-pressure flushing of reverse osmosis equipment

　　Regularly perform high flow, low pressure and low pressure on the reverse osmosis equipmentpHThe flushing of the value is conducive to removing the dirt adhering to the membrane surface, maintaining the membrane performance, or when the reverse osmosis equipment feeds waterSDISuddenly increase over5.5At the above times, low-pressure flushing should be carried out and waitSDITurn on the machine only after the value adjustment is qualified.

　　Reverse osmosis equipment shutdown protection

　　Due to fluctuations in production, reverse osmosis equipment is inevitably shut down frequently. When it is out of service for a short or long time, protective measures should be taken. Improper handling can lead to a decline in membrane performance that cannot be restored.

　　Short-term storage is applicable when the service is out of service15dThe following systems can adopt each1～3dThe method of low-pressure flushing is used to protect reverse osmosis equipment. Practice has found that water temperature20℃At the above times, water is stored in the reverse osmosis equipment3dIt will go bad and stink, and multiply in large numbers. Therefore, it is recommended that the water temperature be higher than20℃Every hour, every2dor1dLow-pressure flushing once, with water temperature lower than20℃At that time, you can do it every time3dPerform a low-pressure flush once. After each flush, all the inlet and outlet valves on the reverse osmosis device of the water purification equipment should be closed.

　　Long-term shutdown protection applies to shutdown15dFor the above-mentioned systems, protective solution should be used at this time(agent)Fill it into the reverse osmosis device of the water purification equipment for protection. Common agent formulas(Composite film)For formaldehyde10(Mass fraction)Isothiazolinone20mg/LSodium bisulfite1(Mass fraction).

　　Chemical cleaning of reverse osmosis membranes

　　Under normal operating conditions, reverse osmosis membranes may also be contaminated by inorganic scale, colloids, microorganisms, metal oxides, etc. The deposition of these substances on the membrane surface can cause a decrease in the output or desalination rate of the reverse osmosis device in the water purification equipment, an increase in pressure difference, and even cause irreparable damage to the membrane. Therefore, in order to restore good water permeability and desalination performance, chemical cleaning of the membrane is required.

　　"General3～12It should be cleaned once a month. If it has to be cleaned once a month, it indicates that the pretreatment system should be in place and the operating parameters should be adjusted. If1～3If the equipment needs to be cleaned once a month, it is necessary to improve its operational level. It is rather difficult to determine whether the pretreatment system needs to be improved.

　　6Raw water pretreatment system

　　The reverse osmosis system is the core component of the entire pure water system. Only through reverse osmosis can the standard of pure water be achieved. The reverse osmosis system mainly adopts membrane filtration technology. Then water molecules can pass through the reverse osmosis membrane. Some other ions such as calcium, magnesium and sodium are discharged along with the wastewater. The following are the components of this system.

　　1.Precision filter

　　It mainly filters out large particle molecules in water.

　　2.Special high-pressure pump

　　Provide strong power for reverse osmosis equipment.

　　3.Reverse osmosis membrane

　　Reverse osmosis membranes employ membrane filtration technology. The purpose of purifying water is achieved by allowing water molecules to pass through while other ions cannot.

　　It is of great significance to rely on the production of pure water. Therefore, to produce pure water, it is essential to choose a place with relatively good raw water quality. Mountain springs, deep Wells, etc. Here, a very important index is involved, which is "electrical conductivity". Generally speaking, the lower the electrical conductivity. The purer the water. The water treatment processes adopted are all reverse osmosis systems. The treated water can generally reach90%- 99%The desalination rate. Now I'll introduce the components of this system.

　　1.Raw water pump

　　The raw water pump is used to provide raw water pressure for the raw water pretreatment system. If the raw water has pressure, this equipment can be dispensed with. The general requirement is the pressure of the raw water>=0.3MP

　　2.Raw water tank

　　The function of the raw water tank is simpler; it is used to store raw water. This is to serve as a transit in case the raw water supply fails.

　　3.Quartz sand filter

　　This device is mainly used to filter out microorganisms and dust in water to make the raw water clear.

　　4.Activated carbon filter

　　This device is mainly used to filter out residual chlorine in water.

　　5.Dosing system (cation exchange system)

　　Cation exchange systems are mostly used in small-scale systems. For large-scale systems, dosing systems are often used to directly add scale inhibitors.

　　7Main process flow description

　　Raw water tank

　　It stores raw water and is used to settle large sand particles and other sedimentable substances in the water. At the same time, it buffers the impact of unstable water pressure in the raw water pipe on the water treatment system. (Such as the response of pressure sensors caused by too low or too high water pressure).

　　Raw water pump

　　Constant system water supply pressure and stable water supply volume.

　　Multi-media filter

　　The filter with multiple filtration layers is mainly designed to remove particles such as sand, rust, colloidal substances and suspended matter contained in the raw water20umThe above-mentioned substances can be controlled by manual valves or fully automatic controllers for a series of operations such as backwashing and forward washing. Ensure the quality of water produced by the equipment and extend its service life.

　　Activated carbon filter

　　The system adopts shell activated carbon filters. Activated carbon can not only adsorb electrolyte ions but also perform ion exchange adsorption. Adsorption by activated carbon can also increase the oxygen consumption of potassium permanganateCOD"By"15mg/L(O2)drop 2～7mg/L(O2)In addition, due to the adsorption effect, the concentration of adsorbed replication on the surface increases, thus also playing a catalytic role, removing pigments, odors, a large amount of biochemical organic matter in water, reducing the residual chlorine value and pollutants in water, and removing trihalides in water.THMAnd other pollutants. Meanwhile, the equipment is equipped with a self-maintenance system and has very low operating costs.

　　Ion softening system/Dosing system

　　R/O The device is designed to dissolve solid substances for concentrated discharge and the utilization of fresh water, and to prevent the concentrated water end, especiallyROA concentrated water side of a membrane module appears behind the device CaCO3,MgCO3,MgSO4,CaSO4,BaSO4, SrSO4, SiSO4The concentration product is greater than its equilibrium solubility constant and crystallizes out,Damage the inherent characteristics of the membrane element ,Before entering the reverse osmosis membrane module,Ion softening devices should be used or an appropriate amount of scale inhibitor should be added to prevent carbonates, SiO2,The crystallization of sulfate.

　　Precision filter

　　The precision filter is adopted to remove the residual suspended solids, non-straight particles and colloids and other substances in the influent water, so as toROAfter waiting for the system 　The equipment operates more reliably and continuously. The filter element is5umMelt-blown filter elements are designed to prevent any leakage from the upper-level filtration unit5umThe removal of impurities. To prevent entry into the reverse osmosis device and damage to the membrane surface, thereby damaging the membrane's desalination performance.

　　Reverse osmosis system

　　The reverse osmosis device uses sufficient pressure to make the solvent (usually water) in the solution pass through the reverse osmosis membrane (or semi-permeable membrane) and separate it out. Because this process is opposite to the direction of natural osmosis, it is called reverse osmosis. Reverse osmosis can adapt to various types of raw water with different salt contents, especially in water treatment projects with high salt content, it can achieve excellent technical and economic benefits. Reverse osmosis has a higher desalination rate, higher recovery rate, stable operation, small floor space, and simple operation. While removing salt, reverse osmosis equipment also removes most colloids and large-molecular-weight organic substances.

　　8Main uses

　　1It is used to produce pure water and high-purity water required for processes in the electronics industry, such as picture tube glass shells, picture tubes, liquid crystal displays, circuit boards, computer hard disks, integrated circuit chips, and monocrystalline silicon semiconductors.

　　2It is used to produce softened water and desalinated pure water for the feed water of thermal power generation boilers, medium and low pressure boilers in factories and mines.

　　3It is used to produce pure water for large-volume medical parenterals, injections, pharmaceuticals, biochemical products, medical sterile water and pure water for artificial kidney dialysis, etc., which are required by the pharmaceutical industry.

　　4It is used for the production of drinking purified water, distilled water, mineral water for the beverage (including alcoholic beverages) industry, brewing water for alcoholic beverages and pure water for blending.

　　5The production of domestic water and drinking water from seawater and brackish water;

　　6Prepare deionized water for electroplating processes; Pure water for battery (storage battery) production process; Automobiles, household appliances, building materials products 　Surface coating and cleaning water; Pure water for coated glass Hardening and desalination water required for textile printing and dyeing processes;

　　7Petrochemical industry, such as cooling water for chemical reactions; Process pure water for the manufacturing of chemical agents, fertilizers and fine chemicals, and cosmetics;

　　8A good water supply network system for hotels, buildings, communities, airports, real estate properties and swimming pool water quality purification;

　　9Wastewater treatment and reuse in circuit boards, electroplating, and the electronics industry;

　　10The treatment of wastewater from domestic life, hospitals, leather tanning, dyeing and printing, papermaking industries, and leachate from garbage.

　　9The hazards of concentration polarization

　　During the reverse osmosis membrane separation process, after water molecules pass through, the salt content at the membrane interface increases, forming a higher concentrated water layer. This layer forms a significant concentration gradient with the concentration of the feed water flow. This phenomenon is called membrane concentration polarization.concentration polarization" Concentration polarization can have a detrimental impact on operation.

　　(1Due to the high concentration in the interface layer, the osmotic pressure will increase accordingly. When the osmotic pressure increases, it is bound to cause a decrease in the water production under the original operating conditions. To achieve the original water production volume, the water supply pressure needs to be increased, which will increase the energy consumption of the product water

　　(2) Due to the increase in salt concentration in the interface layer, on both sides of the filmΔcIncrease it to enhance the water and salt permeation of the product.

　　(3) Due to the increase in the concentration of the interface layer, the tendency of substances prone to scaling to precipitate is enhanced, leading to fouling of the membrane. To restore performance, the scale needs to be cleaned frequently, which may cause an irreversible decline in membrane performance.

　　(4) The concentration gradient formed, when certain measures are taken to make the salt diffuse away from the membrane surface, but the diffusion rate of colloidal substances is hundreds or even thousands of times slower than that of salt. Therefore, concentration polarization is an important cause of colloidal contamination on the membrane surface.

　　The result of concentration polarization is that the osmotic pressure of brine increases, and thus the pressure required for reverse osmosis also needs to increase. In addition, it may also cause certain insoluble salts (such as.CaSO4It precipitates on the membrane surface. Therefore, during operation, it is necessary to keep the brine side in a flocculation state to reduce the degree of concentration polarization.

　　10Process flow

　　Source water tank→Source water booster pump→Multi-media filter→Activated carbon filter→Cation resin softener→Precision filter→Level OneROReverse osmosis pure water system→Level 2ROReverse osmosis pure water system→Water-air mixer→Ozone machine→Stainless steel pure water tank→ Fully automatic filling line

　　11Precautions for Operation

　　Whether pure water equipment can operate normally for a long time mainly depends on maintenance. If the equipment is maintained carefully, it will be in good condition. Therefore, during the operation of the pure water equipment, it is necessary to pay attention not to damage the machine. Attention should be paid in the operation of pure water equipment

　　1.Prevent filter media from entering the reverse osmosis device: Select an appropriate filter outlet device to prevent sand and activated carbon leakage from the filter. Select the appropriate activated carbon to prevent powder shedding during use.

　　2.Large-scale pure water equipment that uses tap water as the water source should set up an independent water supply system. This can not only ensure the stable operation of the water supply system but also reduceROThe instantaneous impact on the entire plant's water supply network when the system starts or stops. whenROWhen the device directly takes water from the raw water pipeline network, high and low pressure protection facilities should be set up, as the pressure in most water supply networks fluctuates greatly.

　　3.First, the compatibility between chemicals should be considered, and second, the compatibility between chemicals and membrane materials should be taken into account. For example,ROCoagulants, coagulant AIDS, coagulants, reducing agents and scale inhibitors are often used simultaneously in the system. Since the limbs in natural water usually carry a negative charge, cationic coagulants with a positive charge are typically used. To preventR0The device is scaling.ROAlmost all the water inlet ends have taken into account the measure of adding scale inhibitors, and these scale inhibitors are almost all negatively charged. Therefore, it is necessary to avoid the reaction between cationic coagulants and anionic scale inhibitors to prevent the deposition of colloidal compounds generated by the reaction on the membrane surface.

　　The above points are extremely important during the use of pure water equipment. They not only protect the equipment but also guarantee the production.