13. How long is the maximum allowed shutdown time without system flushing?

If the system uses a retarder, when the water temperature is between 20-38 ℃, it takes about 4 hours; At temperatures below 20 ℃, approximately 8 hours; If the system is not usedscale inhibitorAbout one day.

How can we reduce the energy consumption of membrane systems?
Low energy consumption membrane elements are sufficient, but it should be noted that their desalination rate is slightly lower than that of standard membrane elements.

15. reverse osmosisCan the pure water system be started and stopped frequently?

The membrane system is designed based on continuous operation, but in actual operation, there will always be a certain frequency of startup and shutdown. When the membrane system is shut down, it is necessary to use its produced water or pre treated qualified water for low-pressure flushing to replace high concentration but scale inhibitor containing concentrated water from the membrane elements. Measures should also be taken to prevent water leakage in the system and the introduction of air, as if the components lose water and dry up, irreversible loss of water production flux may occur. If the shutdown is less than 24 hours, there is no need to take measures to prevent microbial growth. If the downtime exceeds the above regulations, protective solution should be used for system preservation or timed flushing of the membrane system. Zhangjiagang water treatment manufacturer Zhangjiagang bottled water filling machine manufacturer

How to determine the direction of installing saltwater sealing rings on membrane components?

The saltwater sealing ring on the membrane element is required to be installed at the inlet end of the element, with the opening facing the inlet direction. When the pressure vessel is filled with water, its opening (lip) will further open to seal the bypass flow of water between the membrane element and the inner wall of the pressure vessel.

How to remove silicon from water?

Silicon in water exists in two forms, active silicon (monomeric silicon) and colloidal silicon (multicomponent silicon): colloidal silicon does not have the characteristics of ions, but its scale is relatively large. Colloidal silicon can be intercepted by fine physical filtration processes, such as reverse osmosis, and can also be reduced in water content through coagulation techniques, such as coagulation clarification tanks. However, those separation techniques that rely on ion charge characteristics, such asion exchange resinThe continuous deionization process (CDI) has limited effectiveness in removing colloidal silica.
The size of activated silicon is much smaller than colloidal silicon, so most physical filtration techniques such as coagulation clarification, filtration, and air flotation cannot remove activated silicon. The processes that can effectively remove activated silicon are reverse osmosis, ion exchange, and continuous electrodeionization.

What is the impact of pH on removal rate, water production, and membrane lifespan?

　 reverse osmosis membraneproduceThe pH range corresponding to the product is generally 2-11. pH has little effect on the membrane performance itself, which is one of the significant characteristics different from other membrane products. However, the properties of many ions in water are greatly affected by pH. For example, weak acids such as citric acid mainly exist in a non-ionic state under low pH conditions, but dissociate and become ionic at high pH values. Due to the high charge level of the same ion, the removal rate of the membrane is high. If the charge level is low or uncharged, the removal rate of the membrane is low. Therefore, pH has a significant impact on the removal rate of certain impurities.

What is the relationship between influent TDS and conductivity?

When obtaining the inlet conductivity value, it must be converted into TDS value so that it can be input during software design. For most water sources, the conductivity/TDS ratio is between 1.2 and 1.7. In order to conduct ROSA design, a ratio of 1.4 is used for seawater and a ratio of 1.3 is used for brackish water conversion, which usually yields a good approximate conversion rate.

20. How to know if the membrane has been contaminated?

The following are common symptoms of pollution:
Under standard pressure, the water production decreases
In order to achieve the standard water production rate, it is necessary to increase the operating pressure
The pressure drop between the inlet water and the concentrated water increases
The weight of membrane components increases
Significant changes in membrane removal rate (increase or decrease)
When the component is removed from the pressure vessel, water is poured onto the inlet side of the upright membrane component. Water cannot flow through the membrane component and only overflows from the end face (indicating that the inlet channel is blocked).

21. How to prevent the growth of microorganisms inside the original packaging of membrane components?

When the protective solution becomes turbid, it is likely due to the growth of microorganisms. Membrane components protected with sodium bisulfite should be checked every three months. When the protective solution becomes turbid, the components should be removed from the sealed storage bag and soaked in fresh protective solution with a concentration of 1% (by weight) food grade sodium bisulfite (not activated by cobalt) for about 1 hour. The components should be resealed and sealed, and drained before repackaging.

22. RO membrane elements and IX ionsexchange resinThe entryWhat are the water requirements?

In theory, entering the RO and IX systems should not contain the following impurities:
suspended solids
colloid
calcium sulfate
algae
bacteria
Oxidants, such as residual chlorine, etc
Oil or lipid substances (must be below the detection limit of the instrument)
Organic compounds and iron organic complexes
Metal oxides such as corrosion products of iron, copper, and aluminum
The quality of incoming water will have a significant impact on the lifespan and performance of RO components and IX resin.

What impurities can RO membranes remove?

RO membrane can effectively remove ions and organic matter, and reverse osmosis membrane has a higher removal rate than nanofiltration membrane. Reverse osmosis can usually remove 99% of the salt content in the feedwater, and the removal rate of organic matter in the influent is ≥ 99%.

24. How do you know which cleaning method to use for your membrane system?

In order to achieve the desired cleaning effect, it is very important to choose appropriate cleaning agents and steps. Incorrect cleaning can actually deteriorate system performance. Generally speaking, inorganic scaling pollutants, * using acidic cleaning solutions, microbial or organic pollutants, * using alkaline cleaning solutions.

Why is the pH value of RO produced water lower than that of the incoming water?

When understanding the equilibrium between CO2, HCO3-, and CO3=, the answer to this question can be found. In a closed system, the relative content of CO2, HCO3-, and CO3=varies with pH value. Under low pH conditions, CO2 accounts for the majority, while in the medium pH range, it is mainly HCO3-, and in the high pH range, it is mainly CO3=. Due to the fact that RO membranes can remove soluble ions but not soluble gases, the CO2 content in RO produced water is basically the same as that in RO influent. However, HCO3- and CO3=can often be reduced by 1-2 orders of magnitude, which breaks the equilibrium between CO2, HCO3-, and CO3=in the influent. In the series of reactions, CO2 will combine with H2O to undergo the following reaction equilibrium transfer until a new equilibrium is established.
HCO3－ CO2 + + H+ H2O
If the influent contains CO2, the pH value of the RO produced water will always decrease. For most RO systems, the pH value of the reverse osmosis produced water will decrease by 1-2 pH values. When the influent alkalinity and HCO3- are high, the pH value of the produced water will decrease even more.

A very small amount of incoming water, containing less CO2, HCO3- or CO3=, results in less change in the pH value of the produced water. In some regions, there are regulations for the pH value of drinking water, generally ranging from 6.5 to 9.0. According to our understanding, this is to prevent corrosion of the water supply pipeline, and drinking water with low pH value itself will not cause any health problems. * Many commercially available carbonated beverages have a pH value between 2 and 4.

Fault analysis of reverse osmosis equipment system

The most common problems in reverse osmosis systems are the decrease in desalination rate and the decrease in product water volume. If either or both of them slowly decrease, it may be a common phenomenon of dirt or scale formation, which can be solved by appropriate cleaning; And sudden or rapid performance decline indicates that there is a problem or improper operation of the processing system. A problem has occurred and needs to be resolved as soon as possible. Delay may result in the reverse osmosis membrane being unable to restore its original performance.
The prerequisite for discovering problems in a timely manner is to keep corresponding records. When the desalination rate and water production of the system decrease, the instrument should be calibrated first to avoid misjudgment due to instrument reasons. These instruments include conductivity meters, flow meters, pressure gauges, temperature gauges, etc. Secondly, it is necessary to standardize the recorded operational data. Changes in temperature, influent TDS, recovery rate, service life, and water flux can cause variations in desalination rate and water production. By calculating the standardized water production and desalination rate, and comparing them with the initial operating data, it is confirmed that the system has *.
There are three main types of faults in reverse osmosis systems: reduced permeability, increased salt permeability (decreased desalination rate), and increased pressure drop. However, there are many reasons for these faults, and efforts should be made to identify the essence of the problem from these faults and implement maintenance and repair measures as soon as possible.
The fault analysis items and countermeasures are shown in Table 4-3.

By analyzing the changes and trends in these operating parameters, the cause of the malfunction can be determined. Table 4-4 lists the causes and solutions of the reverse osmosis system malfunction from another perspective for reference.

Main measures for troubleshooting reverse osmosis systems

1. Verify instrument operation
Including pressure gauges, flow meters, pH meters, conductivity meters, thermometers, etc., recalibrate if necessary.

2. Recheck the operational data
Check the operation records, changes in flux and desalination rate, considering the effects of temperature, pressure, feedwater concentration, membrane age, etc. on yield and desalination rate.

3. Evaluate possible mechanical and chemical issues
Mechanical problems mainly include damage to O-rings, saltwater seals, pumps, pipelines and valves, and faulty instruments. One of the chemical problems is improper addition of acid. High doses of acid can damage membranes or cause sulfate based scaling (if sulfuric acid is used), while low doses can lead to carbonate or metal hydroxide based scaling or pollution; Secondscale inhibitorImproper addition, high doses may lead to contamination, while low doses may cause scaling.

4. Analyze the changes in the chemical conditions of the feed water
Comparing the current feed water analysis with the benchmark data at the time of design, changes in the chemical conditions of the feed water will result in the need to add pre-treatment or update existing pre-treatment equipment.

5. Identify pollutants
One is to analyze the inorganic components of the feed liquid, saltwater, and product liquid, including total organic carbon (TOC), turbidity, and pH value TDS、 Total suspended solids (TSS), SDI, and temperature, among which the determination of SDI, TSS, and turbidity can provide a basis for particulate matter pollution, and the determination of TOC can predict the tendency of organic matter pollution; The second is impregnation and analysis of the feed liquid cylinderfilter(Preferred method) or SDI filter pad.

6. Choose a suitable cleaning solution
In the selection of cleaning solutions, the following factors should be considered: the type of membrane anddetergentCompatibility of selection, requirements for cleaning equipment, structural materials of the system, identification of pollutants, etc.

Zhangjiagang Suzhou Renyu Machinery Co., LtdWe are a professional manufacturer specializing in the research, development, and production of various beverage machinery. The company adheres to a market-oriented approach, using * technology, scientific management, product quality, and fast and thoughtful after-sales service to provide customers with supporting services such as process consultation, graphic design, installation and commissioning, technical training, etc. With a high-quality R&D team and rich production and manufacturing experience, the company has won the trust of users at home and abroad. The company's products are exported to Indonesia, Malaysia, Russia, Japan, etc. The company regards product quality as the life of enterprise development and has established a strict quality assurance system. The company adheres to the principle of "quality *, user *" and sincerely welcomes new and old customers to visit and patronize.

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