Industrial water desalination from China for chemical industry

With people's attention to drinking water safety, reverse osmosis water purifier is gradually becoming the mainstream of modern household water purification products. It adopts reverse osmosis filtration technology, and the core element is reverse osmosis membrane. Only water molecules can pass through the reverse osmosis membrane and remain for drinking; Bacteria, viruses (including SARS virus and the smallest BSE in the world can be effectively intercepted), scale, heavy metal ions, radioactive substances and other harmful substances, various pollutants, and soluble salt ions can not pass through the membrane, but become concentrated water discharged. The reverse osmosis pure water machine ensures the safety and reliability of the effluent quality, and there is no problem of water source pollution.The domestic reverse osmosis pure water machine is a domestic pure water device used for producing domestic direct drinking water by reverse osmosis membrane method.The water purification system of the pure water machine takes the reverse osmosis membrane as the core. The part before the reverse osmosis membrane can be called pre-treatment, and the part after the reverse osmosis membrane is called post-treatment. Reverse osmosis pure water machine is a device that integrates microfiltration, adsorption, ultrafiltration, reverse osmosis, UV sterilization, ultra purification and other technologies to directly convert tap water into ultra pure water. Reverse osmosis (RO) membrane is the core element of reverse osmosis pure water unit. The purified water produced by reverse osmosis pure water mechanism is fresher, healthier and safer than barreled water. It is widely used.Cleaning method of household machine1. Cut off the power supply of the water dispenser.2. Clean the surface, tray and other parts. Clean the surface with neutral detergent, but do not use organic detergent, otherwise it will corrode the surface of water dispenser. Alcohol cotton balls can be used to clean the water inlet, inner wall, faucet, ponding tray, etc; Insert the water bottle vertically downward into the smart seat on the upper part of the machine, turn on the red hot water tap and blue cold water tap, turn off the tap until there is water discharged, and then hold the bottle body with both hands and take out the water bottle upward.3. Clean the outside of the water dispenser and the smart seat.4. Pour an appropriate amount of special cleaning disinfectant into the water storage tank. After soaking for 10 minutes, turn on the water tap until the disinfectant is red and blue.5. Unscrew the drain valve at the back or bottom of the machine and drain the disinfectant in the water dispenser.6. Rinse repeatedly with boiling water or barreled water for several times.7. Tighten the drain valve and complete the disinfection and sterilization procedures.Detailed explanation of reverse osmosis household filtration systemPrimary filtration: 5 micron PP fiber filter cartridge (remove impurities visible to the naked eye in water, including sediment, red insects, rust, etc.)Function: pre-treatmentService life: according to the raw water quality, it is recommended to replace it once every 3 monthsSecond stage filtration: granular activated carbon filter cartridge (strong adsorption of organic matter, different colors and peculiar smell, such as pesticides, chlorine, etc.)Function: pre-treatmentFeatures: adsorb organic matter, different colors and peculiar smell in water through physical action, such as pesticides and chlorine, so as to achieve the purposes of disinfection, decolorization, purification and decontaminationService life: according to the raw water quality, it is recommended to replace it once every 6-12 months.Tertiary filtration: high density sintered activated carbon filter cartridge (strong adsorption of color, odor and organic matter (such as pesticides) in raw water)Function: pre-treatmentFeature:1. It is made by high-density process. The micropores formed on the surface and inside of the  filter cartridge are developed, with high arrangement density, uniform and dense arrangement, fast adsorption speed and high efficiency.2. The filter element integrates the advantages of ultrafiltration membrane and activated carbon. At the same time, it overcomes the shortcomings of membrane and ordinary activated carbon filtration. For example, the membrane only intercepts the substances in the water, but has no effect on the peculiar smell and color in the water, and can not remove the color and smell in the water, such as the color brought by bleaching powder and natural pigment. Granular activated carbon will form gap filtration in the process of water scouring, so that some water hardly contacts with activated carbon when passing through the carbon bed.Service life: according to the raw water quality, it is recommended to replace it once every 6-12 monthsFourth stage filtration: RO membrane reverse osmosis technology (apply membrane separation technology to remove all bacteria, viruses, heavy metals and organic compounds in water)Function: under pressure, water becomes pure water through reverse osmosis membrane; Impurities in water are intercepted by reverse osmosis membrane and carried out by concentrated water. The use of reverse osmosis technology can effectively remove inorganic salt ions, colloids, bacteria, viruses, bacterial endotoxin and most organic matters in water;Service life: according to the raw water quality and water consumption, it is recommended to replace it once every 18-36 monthsThe Fifth stage of filtration: Post placed antibacterial activated carbon (adsorb peculiar smell, adjust the taste of water, mellow and sweet, conducive to human absorption).Features: the silver loaded activated carbon made of coconut shell can adjust the pH of water quality, make the taste of purified water sweet and mellow (weakly alkaline water), inhibit bacteria in water and reduce secondary pollution.Suitable OccasionIt is suitable for families, offices and other places. It is mainly used for drinking. Features: fresh direct drink, good taste. When the direct drinking machine is in the working state of water making: the water purification outlet is opened and the sewage outlet is closed. In the water making state, raw water (unprocessed water) enters from the water inlet. First, it is filtered by the ultrafiltration membrane filter element to effectively remove the sediment, rust, bacteria, colloid, algae, macromolecular organic matter and other harmful substances in the water in a high-precision and pure physical way, and then magnetize the water purified by the ultrafiltration membrane through multi-functional nanocrystals, natural calcium ion spheres and KDF Mineralization, activation, weak alkalization, and removal of heavy metal ions, followed by high-quality coconut shell activated carbon and special dechlorination activated carbon filter element to effectively remove organic matters (such as chloroform), improve the taste and form fresh direct drinking water.Working PrincipleAll pure water machines in the domestic market should have five levels of filtration. The first level is PP cotton filter element, the second and third levels are granular activated carbon, the fourth level is RO reverse osmosis membrane, and the fifth level is post activated carbon, which is mainly used to improve the taste. The filter element of the filter device of household (commercial) pure water machine has a service life. The fiber filter element can generally be used for 6 months and the activated carbon filter element is generally 12 months. Their service life completely depends on the local water quality, water pressure and water consumption; When the filter element is replaced regularly, the shelf life of reverse osmosis membrane is 2 years. If the pretreatment is sufficient, its actual service life can reach 8 years and the removal rate can reach more than 99%. The pure water produced by the pure water machine can not only be used for daily drinking, such as making tea, coffee, milk powder, refrigeration, etc. the direct raw drinking effect is better. The ice made from pure water is crystal clear, clean and hygienic. The pure water can also be used for steaming rice, boiling soup, cooking porridge, etc. the food tastes pure. When you need to eat raw fruits and vegetables, you'd better wash it with pure water for the last time, which makes you feel more at ease, Pure water will not stimulate the skin. If you wash your face with it, it can play a cosmetic role.The post-treatment of pure water machine can adopt activated carbon filter element, ultraviolet sterilization lamp, etc.The function of post activated carbon filter element is to deeply treat the pure water produced by reverse osmosis membrane, remove volatile organic compounds and odor in the water and improve the taste of pure water. Especially for the pure water machine using pressure water storage bucket, the rear activated carbon can effectively remove the rubber smell produced by the water storage bucket.Ultraviolet sterilization lamp is often used in high-grade pure water machine, which can prevent purified water from secondary pollution.Common Faults1. If the transformer burns out and the raw water pressure fails, it will directly lead to the failure of the water pump to start and unable to produce purified water;2. Check whether the PP filter element is blocked, resulting in water unable to flow, pressure rise and water leakage. If this phenomenon occurs, replace the filter element;3. The outflow water quality standard is unqualified. Check whether the reverse osmosis membrane is blocked or seriously polluted due to long-term use;4. The pressure bucket has been filled with water, but the pure water cannot flow out. It may be that the rear activated carbon is blocked and must be replaced;5. The machine has stopped running, but there is still water flowing out. It is necessary to check whether the water inlet solenoid valve operates normally;6. The machine cannot be shut down due to frequent startup. It is necessary to check whether the high-voltage switch fails

 What is ultrafiltration technology in water treatment?In the process of ultrafiltration, the aqueous solution flows through the membrane surface under the push of pressure. The solvent (water) and small molecular solute smaller than the membrane pore permeate the membrane and become the purified solution (filtrate). The solute and solute group larger than the membrane pore are intercepted and discharged with the water flow to become the concentrated solution. The ultrafiltration process is dynamic filtration, and the separation is completed in the flow state. The solute is only deposited on the membrane surface, the ultrafiltration rate decreases to a certain extent and tends to balance, and can be recovered by cleaning.Ultrafiltration system is also closely related to reverse osmosis system. In many aspects, they are similar.Ultrafiltration device, like reverse osmosis device, has plate type, tube type (internal pressure tube type and external pressure tube bundle type), roll type, hollow fiber type and other forms. Concentration polarization is a natural phenomenon in membrane separation process. How to minimize this phenomenon is one of the important topics of ultrafiltration technology. The measures taken are: ① increase the water flow velocity on the membrane surface to reduce the thickness of the boundary layer and take away the trapped solute from the water in time; ② Take physical or chemical washing measures.What is the principle of ultrafiltration technology?      The principle of ultrafiltration is not complicated. During ultrafiltration, due to the accumulation of trapped impurities on the membrane surface, a concentration polarization phenomenon will occur. When the solute concentration reaches a certain limit, the gel layer will be formed, resulting in a sharp decrease in the permeability of the membrane, which limits the application of ultrafiltration. Therefore, it is necessary to study through experiments to determine the best process and operating conditions, minimize the influence of concentration polarization, and make ultrafiltration a reliable reverse osmosis pretreatment method.      Ultrafiltration is a membrane separation technology (UF). It can purify, separate or concentrate the solution. Ultrafiltration is between microfiltration and nanofiltration, and there is no obvious boundary between them. Generally speaking, the pore diameter of ultrafiltration membrane is between 0.05 um – 1 nm and the operating pressure is 0.1 – 0.5 MPa. It is mainly used to intercept and remove macromolecular substances such as suspended solids, colloids, particles, bacteria and viruses in water. Ultrafiltration membrane can be divided into organic membrane and inorganic membrane according to membrane materials. According to the appearance of the membrane, it can be divided into: flat plate type, tube type, capillary type, hollow fiber type and porous type. At present, domestic ultrafiltration water purifiers are mainly hollow membranes.      The work of ultrafiltration membrane is mainly based on screening mechanism, and water purification is carried out by working pressure and pore size of membrane. Taking hollow fiber as an example, the water inlet mode can be divided into external pressure type: raw water enters from outside the membrane wire, and purified water is prepared from inside the membrane wire. On the contrary, it is internal pressure type. The working pressure of internal pressure type is lower than that of external pressure type. Ultrafiltration membrane has been widely used in many fields, such as advanced treatment of drinking water, concentration and separation of industrial ultrapure water and solution.Advantages and disadvantages of ultrafiltration technology      The ultrafiltration equipment system has high recovery rate and excellent product quality, which can realize high-efficiency separation, purification and high multiple concentration of materials. The system is made of sanitary pipe valves, which are clean and sanitary on site and meet the requirements of GMP or FDA production specifications. The system has advanced process design, high degree of integration, compact structure, less floor area, simple operation and maintenance, and low labor intensity.        There is no phase change in the treatment process, which has no adverse effect on the components in the material, and the separation, purification and concentration process is always at room temperature. It is especially suitable for the treatment of heat sensitive substances, completely avoids the disadvantage of high temperature damaging bioactive substances, and effectively retains the bioactive substances and nutrients in the raw material system.        Ultrafiltration components shall be handled with care and protected. As ultrafiltration components are precision equipment, they shall be handled with care during use and installation, and shall not be damaged. If the components are out of service, wash them with clean water first, then add 0.5% formaldehyde aqueous solution for disinfection and sterilization, and seal them well. In winter, the components shall be subject to anti freezing treatment, otherwise the components may be scrapped.        The ultrafiltration equipment system has low energy consumption and short production cycle. Compared with the traditional process equipment, the equipment operation cost is low, which can effectively reduce the production cost and improve the economic benefits of the enterprise.        Ultrafiltration technology has the advantages of simple operation, low cost, no need to add any chemical reagent, especially the experimental conditions of ultrafiltration technology are mild, there is no phase change compared with evaporation and freeze-drying, and does not cause the change of temperature and pH, so it can prevent the denaturation, inactivation and autolysis of biological macromolecules. In the preparation technology of biological macromolecules, ultrafiltration is mainly used for desalination, dehydration and concentration of biological macromolecules. Ultrafiltration also has some limitations, it can not directly obtain dry powder preparation. For protein solution, generally only 10 ~ 50% concentration can be obtained.Ultrafiltration Membrane     The key of ultrafiltration technology is membrane. There are various types and specifications of membranes, which can be selected according to the needs of work. Early membranes were isotropic homogeneous membranes, i.e. commonly used microporous films, with pore sizes of 0.05mm and 0.025mm. The relatively thin (about 1.0 mm) porous layer with a certain thickness (about 0.1 mm) and a relatively thin (about 1.0 mm) porous membrane are used as a support layer. The skin layer determines the selectivity of the membrane, while the sponge layer increases the mechanical strength. Because the skin layer is very thin, it has high efficiency, good permeability, large flow, and is not easy to be blocked by solute, resulting in the decrease of flow rate. Commonly used membranes are generally made of acetic acid fiber or nitric acid fiber or a mixture of the two. Recently, in order to meet the needs of sterilization in pharmaceutical and food industry, non fiber anisotropic membranes have been developed, such as polysulfone membrane, polysulfone amide membrane and polyacrylonitrile membrane. The membrane is stable at pH 1 ~ 14 and can work normally at 90 ℃. Ultrafiltration membrane is usually relatively stable. If used properly, it can be used continuously for 1 ~ 2 years. If not used temporarily, it can be soaked in 1% formaldehyde solution or 0.2% NaN3 for storage. The basic performance indexes of ultrafiltration membrane mainly include: water flux [cm3 / (cm2? H)]; Rejection rate (expressed as a percentage); Chemical and physical stability (including mechanical strength), etc.   There are three common operation modes in ultrafiltration process.(1) Single stage intermittent operation: in the ultrafiltration process, in order to reduce the influence of concentration polarization, the membrane module must maintain a high feed liquid flow rate, but the membrane permeation flux is small, so the feed liquid must be circulated in the membrane module for many times to concentrate the feed liquid to the required degree, which is the most basic feature of the industrial filtration device. Batch operation is applicable to the treatment of products in laboratory or small-scale batch production.(2) Single stage continuous operation: compared with intermittent operation, it is characterized by that the ultrafiltration process is always carried out at the concentration close to the concentrated solution, so the permeability and rejection rate are low. In order to overcome this disadvantage, multi-stage continuous operation can be adopted.(3) Multi stage continuous operation: the concentration of circulating liquid in each section increases in turn, and the concentrated liquid is led out in the last section. Therefore, the feed liquid in the previous sections can be operated at a lower concentration. This continuous multi-stage operation is suitable for large-scale industrial production..Application of ultrafiltration technology     As a membrane separation technology, ultrafiltration has been widely used in various fields of national economy, such as industrial production, medicine and health, environmental protection and people's life. Although it can deal with a wide variety of objects, and people have different purposes, the role of ultrafiltration can be attributed to three functions: purification, separation and concentration.(1) Application in industrial wastewater treatmentIndustrial wastewater treatment is mainly used in: the treatment and application of sugar containing wastewater; Treatment of wastewater containing crude oil; Combined with bioreactor to treat various wastewater; Textile industry, dye and dyeing wastewater treatment and reuse; Treatment of papermaking wastewater; Treatment of radioactive wastewater, etc. For example, in the recovery of dyes from dyeing wastewater, during suspension tie dyeing in printing and dyeing plants, more vat dyes will be discharged from the reduction steamer in production, which is both pollution and waste. Using ultrafiltration technology and polysulfone and polysulfone amide ultrafiltration membrane, printing and dyeing wastewater can be treated without acid neutralization and cooling.(2) Application in pharmaceutical industryThe main applications in pharmaceutical industry are: purification of antibiotics and interferon; Injection and water for injection to remove pyrogen; Plasma and biopolymer treatment; Separation, concentration and purification of proteins and enzymes; Refining and purification of Chinese herbal medicine. For example, the application of heat removal in the pharmaceutical industry.(3) Application in water treatmentThe applications of water treatment mainly include: pure water for electronic industry; Pretreatment of high purity water and water inlet of reverse osmosis components; Production of sterile water for beverages and cosmetics; Production of sterile and heat free raw water for pharmaceutical industry; For example, in the manufacture of mineral water, the water source must be groundwater, which will dissolve some inorganic salts when flowing underground. The combined process of ultrafiltration and microfiltration can be used to produce mineral water that meets the drinking water standard.(4) Application in food fermentation industryThe main applications in food fermentation industry are: wine clarification and sterilization; Ripening soy sauce; Sterilization, clarification and decolorization of vinegar; Purification of fermentation broth; Clarification of fruit juice; Recovery of sugar juice and sugar liquid; Recovery of whey protein; Concentration of skimmed milk, etc.

How Does Reverse Osmosis System Work?Reverse osmosis membranes are membranes with selective permeability. When liquid or gas passes through the reverse osmosis membranes, some components pass through while others are intercepted. In fact, reverse osmosis membranes are permeable to any component except at very different rates. During the reverse osmosis process, the permeability of the solvent (water) is much higher than that of the solute (salt) dissolved in water. Solvents and solutes are separated by reverse osmosis membrane to obtain pure water and concentrated salt solution.Water in operation of reverse osmosis flows to the side of the salt solution through osmosis until a new equilibrium is reached. Apply an additional pressure on the side of the salt solution equal to the reverse osmosis pressure. External pressure will increase the chemical potential on one side of the salt solution, causing the solution to flow to the side of pure water. This phenomenon is called reverse osmosis.There are two ways for water to pass through the membrane, one is through the pores on the membrane, and the other is through the diffusion between the molecular nodes in the membrane. According to the theory, the chemical property of the membrane is that on the solid-liquid interface, water is preferentially adsorbed and passed through, and salt is intercepted. There is a weak chemical binding force between water and the membrane surface, so that water can be dispersed in the membrane structure. The physical and chemical properties of the membrane determine the structure of water than salt in the transfer process.(1) Yielding water - osmotic solutionThe permeate of reverse osmosis and nanofiltration membranes is purified water, so they are also called system yielding water.(2) Concentrated Water - Concentrated LiquidSolutions that do not penetrate the membrane are concentrated in the raw water. Concentrated water is discharged as wastewater in water treatment reverse osmosis system.Applicaiton Of Reverse Osmosis SystemAt present, reverse osmosis system, as the main desalination process, has been widely used in many fields, including oil, power, chemical industry, pharmaceuticals, drinking water.Types of membranesFeaturePurposeUltra low pressure flux membraneUltra low operating pressure, higher water flux, but low desalination rateLow salt waterLow pressure reverse osmosis membraneHigh desalination rate and low water fluxBrackish waterLow pollution reverse osmosis membraneSurface electrical neutrality, good hydrophilicity and strong anti-pollution abilitySurface waterPositive charge reverse osmosis membranePositive charge on surface, higher cation removal rateCation removalSeawater desalination membraneSuper compaction resistance for use in high pressure systemsSeawater desalinationNecessity of Reverse Osmosis PretreatmentVarious raw water contains suspended and soluble substances of certain concentration. Suspension is mainly composed of inorganic salts, colloids, microorganisms, algae and other biological particles. Soluble substances are mainly soluble salts (such as chlorides) and insoluble salts (such as carbonates, sulphates and silicates) metal oxides, acids and bases.During the reverse osmosis process, the volume of influent decreases and the concentration of suspended particles and soluble substances increases. Suspended particles deposit on the membrane, blocking the flow path and increasing friction (pressure drop). Difficult to dissolve beyond its saturation limit is that it will precipitate from concentrated water, form scaling on the membrane surface, reduce the flux of RO membrane, increase the operating pressure and pressure drop, and cause the degradation of yielding water quality. This deposition on the membrane surface is called membrane fouling, which results in a deterioration of system performance. Need to enter reverse osmosis in raw water.The effect of pretreatment of raw water reflects that the absolute values of water quality indexes of pollutants such as TSS, TOC, COD, BOD, LSI and iron, manganese, aluminium, silicon and barium are reduced.Another important water quality indicator of membrane fouling tendency is SDI. Through pretreatment, besides reducing the above indexes to the water requirement range of reverse osmosis system, it is also important to minimize SDI and the ideal SDI (15 minutes) value should be less than 3.In order to control biological pollution, it is necessary to reduce the dead water area on the pipeline and avoid the use of carbon filters. Before RO membrane loading, the pretreatment system and RO device shall be disinfected. After startup, it shall be kept in continuous operation, and biofilm will grow during shutdown.The methods to control microbial pollution include: continuous or periodic use of disinfectants online or offline. Effective disinfection and cleaning methods shall be available after biological pollution of RO.Composition of reverse osmosis systemIt includes process flow, membrane module and shell, high-pressure pump, pressure protection, low-pressure flushing, excessive discharge and system detection.What is the function of high-pressure pump?The selection of pressure and flow of high-pressure pump system is mainly based on the simulation calculation results of running Hyde energy design software imsdesign.The selection of high-pressure pump is generally considered according to the condition after three years of membrane operation.In order to ensure the safety and reliability of the system, the lift and flow specifications can be increased by 10% based on the recommended selection of the calculation results.Manual regulating valve is generally installed at the outlet of high-pressure pump. The pressure required by the system in the initial stage of operation is smaller than that after three years, so manual regulating valve is used to regulate the output of the pump.What is low pressure flushing？Reverse osmosis shutdown automatic membrane flushing. Ro automatically flushes the reverse osmosis membrane when the system is shut down to avoid dirt deposition.How to operate over standard emission？Excessive discharge / shutdown / alarm of pure water qualityWhen the conductivity of pure water exceeds the maximum allowable value, the reverse osmosis system will shut down automatically and give corresponding alarm signals.Pressure gauge: pre membrane pressure, inter membrane pressure and post membrane pressureThermometer: inlet water temperatureFlow meter: produced water flow, concentrated water flowConductivity meter: water inlet conductivity, water production conductivityCommon problemsWhen the water production decreases(1)Changes in the following parameters will reduce the actual water production of the membrane in the system(2)When the pressure of the inlet pump remains unchanged, the inlet water temperature decreases(3)Reduce RO water inlet pressure with throttle valve(4)Increase the produced water back pressure when the inlet pump pressure remains unchanged(5)The influent TDS (or conductivity) increases, which will increase the osmotic pressure that must be overcome when the produced water passes through the membrane(6)The recovery rate of the system increases, which will increase the average influent / concentrated water TDS of the system, thus increasing the osmotic pressure(7)Contamination of membrane surface(8)The pollution of the inlet channel network leads to the increase of inlet concentrated water pressure drop (△ P)Ocpuritech, the best reverse osmosis system manufacturer in China, provides industrial reverse osmosis system, commercial reverse osmosis system, ultrafiltration system, seawater desalination deionized water system and filter cartridge.

Seawater Desalination System Product DisplayWe designed small and portable desalination water system treatment equipment, the flow rate is from 500L/D to 6000L/D, which is very popular. It is also suitable for high salinity groundwater, river water or well water. The characteristics of this kind of seawater reverse osmosis system are small size, compact structure, easy to operation and maintain, easy to move (wheel optional), durable, low noise, etc. , according to the appropriate circuit capacity and motor power, we divide such seawater desalination ro system into brackish water type and seawater desalination type; the whole seawater desalination system is composed of raw water pump, multi-media filter, reverse osmosis main part and cleaning PE water tank , the performance specifications are roughly as follows:Power consumption: 1.5KW-3KWInfluent TDS : ≤38000mg/LProduct water TDS : ≤600mg/LWorking pressure: 1000PSI (60bar)Inlet pressure: 1barWorking temperature: 10-45 ℃Inlet SDI: ≤5Flow ChartSea Water RO System MaintainThe necessity of chemical cleaning and clean water cleaning When operating a reverse osmosis desalination plant, the separated mineral ions, metal salts, microorganisms, algae, colloids and other impurities will accumulate on the membrane surface and then cause RO membrane fouling, which will result in less flow, or a drop in salt rejection, at any time , if the purified water flow drops to the rated standard (under the same conditions), or the purified water salinity increases significantly, it means that the membrane needs to be cleaned; the reasons for membrane fouling are complex, and the fouling characteristics and pollutants may be different, replace In other words, insufficient operating pressure, or a drop in pump flow will result in a drop in net water flow. So, in order to get an appropriate method to solve this problem, the user should analyze the reasons;The most common contamination comes from microorganisms, organic matter, and algae in the sea. Monthly cleaning is required to recover from this type of contamination.Tabel 1:  list the character for common RO membrane pollutionsPollution ReasonMetal oxides(Fe，Mn，Ni，Cu)                                                                                           Common reasonSalt permeate rateMembrane pressure lossFreshwater productivityDouble up rapidly Double up rapidlyDecrease 20-25%Sediments (CaCO3, MgCO3)Increase 20-25％Increase 10-25％Decrease <10％Colloid (Silicon colloid)Double up graduallyDouble up graduallyDecrease ≥50%Microbiology (Germs, algae)Double upDouble upDecrease ≥50% 1. Safe cleaning routines and cleaning steps for sea water purification system. (1). Safe cleaning routinesa. Before use any chemical dose mentioned at the follow charters, be sure to follow the experience that stated here, and claim the detail operation instruction from the dose supplier or the professional.b. While prepare the protecting liquid, be sure stir the solute to dissolved totally and equally.c. Use the freshwater without free chlorine to flush the membrane, the water temperature should not be less than 20℃. The permeated water from the membrane or the water after pre-filtration from a non-rusty pipe can do.d. Before return to normal running, be sure to flush the system under no pressure for about 5 minutes, and then release the freshwater of the initial 30 minutes when the machine begins working.e. There is a water temperature limit on cleaning, if the PH of the water is 2-10, the temperature should be lower than 40℃, and if 10-11, should lower than 35℃, and if 11-12, should lower than 30℃, please keep the cleaning liquid over 15℃, otherwise the cleaning time could be too long. 2. Cleaning and protection chemical dose use instruction for seawater desalination system Cleaning dose operation1. flush the water tank with fresh water at 40~45℃ for 5-10 minutes, till the water turn clean.2. Add fresh water into the tank, at 40~45℃, add alkaline cleaning dose, density at 0.5%~1%, control the PH value at 11-12, cycle for 40 minutes.    3. flush plant with freshwater at 40~45℃ for 10 minutes, till the water be neutral.    4. Add fresh water into the tank, at 40~45℃, add acid cleaning dose, density at 3%, cycle for 15 minutes.    5. flush plant with freshwater at 40~45℃ for 10 minutes, till the water be neutral. Chemical dose and water dose should be used as followed table:50 Liter wateracid liquid 500 mlAlkaline powder 0.5kgProtection liquid 1000 ml   Protection dose operationAdd fresh water into the tank, at normal temperature, add protection liquid, density at 1-2%, cycle for 15-30 minutes, keep the liquid inside the system. Caution: Either the desalination rate or product water flow rate decrease over 15%, the plant should be cleaned immediately, otherwise the life and the plant capacity cannot be recovered any more. 3. PLANT MAINTAINENCE(1). Keep the reverse osmosis desalination plant clean, wipe off the oil stain or splashed seawater(2). Fasten the screw or change the sealing if leakage is found between the pipes(3). Clean or change the precision filter cartridges    a. After running the reverse osmosis desalination plant for some time, the pre-filter cartridge could be stuffed by the impurities in the seawater, this will affect the feed water pressure loss, or feed water flow rate decrease, then could lead to low fresh water productivity. When the reading of the feed water pressure gauge less than 0.1 Mpa , that means the precision filter need to be cleaned or replaced.   b. When replace the cartridge, screw off the housing with the plastic wrench come with the package, put the old cartridge out, and install the new one, and then screw the housing back.   c. The stuffed cartridge can be recovered by dipping it into caustic soda liquid of 5-8% density, for about 6 hours. then flush it with fresh water, then airing to dry.4. TROUBLE SHOOTING