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FAQ
  • What are the potential risks of frequent replacement of reverse osmosis scale inhibitors?
    System stability risk
    1. The chemical properties of scale inhibitors of different brands or models may be different. Replacement may lead to incompatibility between the scale inhibitor and the RO membrane, thus causing oxidation, aging of the membrane surface or formation of new sediments, and affecting the water production, cleaning cycle, etc. of the reverse osmosis system.
    2. Increased cost
    Replacing scale inhibitors not only increases the cost during chemical replacement, but also may lead to frequent replacement of membrane elements due to system instability, further increasing the operation cost.
    3. Operational complexity
    Replacing scale inhibitors involves system shutdown, cleaning, chemical dosing and other operations. Frequent replacement increases the risk of human operation errors (e.g., inaccurate chemical dosage, pollution of chemical tanks, which in turn affects system stability).
  • What work needs to be done when the reverse osmosis feed water quality changes?
    Confirmation and analysis: Figure out what has changed, how much it has changed, and why it has changed.
    Inspect the pretreatment system: Fully check whether the pretreatment equipment (filter, softener, dosing system, ultrafiltration system) is invalid or needs optimization.
    Strengthen water quality detection: Strengthen the detection of key water quality and operation parameters, and readjust the dosing scheme according to the water quality.
    Chemical cleaning: Conduct chemical cleaning in a timely manner according to the equipment operation status.
    Evaluation and preplan: Evaluate the impact of water quality changes on the system, and formulate short-term response and long-term improvement plans.
    Emergency situation: Communicate with the equipment manufacturer, and immediately reduce the system recovery rate! Inspect and replace the security filter element! Adjust system operation parameters (pressure, pH, chemical dosage, etc.).
    Feedback to sales personnel.
  • How to simply judge the cause of reverse osmosis fouling?
    (1) Visual inspection
    When it is determined that the system is fouled and chemical cleaning needs to be carried out, first open the end plate of the pressure vessel and directly observe the accumulation of pollutants in the gap between the end plate of the pressure vessel and the membrane element. The type of pollutants can be basically determined through direct observation, and then the corresponding cleaning scheme can be determined.
    A. Front-section fouling observation
    Pretreatment filter material (sand, activated carbon) leakage, colloidal fouling, organic fouling and biological fouling are serious in the front section. Particulate and mucous fouling can be observed at the inlet of the front membrane elements. In case of biological fouling, fishy and odorous mucous substances will be found, and burning the scraped biological slime (mucous membrane) will produce a burnt protein smell.
    B. End-section fouling observation
    Inorganic salt scaling is serious in the end section of the system, and rough powder can be felt at the end of the membrane elements in the end section. If gas is emitted when dissolved with hydrochloric acid (pH 3~4), the precipitate is most likely CaCO3. Sulfate scale and silica scale are difficult to dissolve even at very low pH. If the scale is soluble in 0.1 mol/L HF solution, it may be silica scale.
    (2) Weighing
    Pollutants adhere to the feed water flow channel of the fouled membrane element, resulting in an increase in the overall weight. Stand the taken out membrane element upright, drain the water and weigh it, and compare it with the reference weight of the membrane element. The excess weight is the weight of the adhered pollutants.
  • How to adjust the cleaning process when the pressure difference of the second stage of reverse osmosis is still large after chemical cleaning?
  • Increase the flushing step before cleaning: Before chemical cleaning, flush the reverse osmosis system with qualified water after pretreatment for a long time and with a large flow rate (the time can be extended to 30-60 minutes) to remove loose impurities and pollutants in the system as much as possible and reduce the burden of chemical cleaning.
  • Optimize the selection and configuration of cleaning solution: Select a more targeted cleaning solution according to the specific composition of pollutants (e.g., acidic cleaning solution for water scale such as calcium and magnesium ions; alkaline cleaning solution or enzyme-containing cleaning solution for organic fouling).
  • Configure the cleaning solution in strict accordance with the formula and concentration requirements to ensure its effectiveness. At the same time, the concentration of the cleaning solution can be appropriately increased, but attention should be paid to avoiding damage to the membrane elements.
  • Adjust the cleaning process parameters:
    • Extend cleaning time: Extend the original cleaning time (generally from the conventional 1-2 hours to 3-4 hours) to make the cleaning solution fully contact and react with pollutants and improve the cleaning effect.
    • Increase cleaning temperature: Appropriately increase the temperature of the cleaning solution within the allowable temperature range of the membrane elements (generally controlled at 30-35℃) to accelerate the chemical reaction rate and enhance the cleaning effect.
    • Increase circulation flow rate: Improve the circulation flow rate of the cleaning solution to form a stronger turbulence in the membrane module, which is conducive to the stripping and discharge of pollutants, but attention should be paid not to exceed the pressure resistance range of the membrane elements.
  • Strengthen flushing after cleaning: After cleaning, thoroughly flush the system with pretreated water until the conductivity, pH and other indicators of the flushing water are close to the feed water, to ensure that the residual cleaning solution is completely removed and prevent secondary pollution or damage to the membrane elements caused by residual cleaning solution.
  • Increase the number of cleanings or adopt step-by-step cleaning: If the pressure difference is not significantly reduced after one cleaning, multiple cleanings can be carried out, and the change of pressure difference can be evaluated after each cleaning.
  • How to solve the rising trend of reverse osmosis feed water conductivity caused by high temperature in summer and the relatively poor quality of reclaimed water feed water?

    Strengthen coagulation and sedimentation: Appropriately increase the dosage of coagulant in the biological aerated filter to make suspended particles, colloids and other impurities in water easier to coagulate and settle, improve the sedimentation effect, and remove part of organic matter and microorganisms.

    Replace the filter material with higher filtration accuracy in the security filter.

    Regularly observe the pH of feed water, and adjust the pH of feed water to the range of 6-8 by adding acid or alkali according to the measured results.

    Appropriately reduce the system recovery rate to avoid the risks of membrane fouling and scaling caused by excessively high salt concentration on the concentrated water side due to excessively high recovery rate.

  • What problems are easy to occur in activated carbon filters and how to solve them?
    Activated carbon powder in the effluent of activated carbon filter: The solution is to adjust the feed water quality, reduce the content of suspended solids and oxidants in the feed water, and reduce backwashing, especially the number of air scrubbing times.
    Too small adsorption capacity and short service life of activated carbon: The solution is to select the appropriate type of activated carbon.
    Failure of activated carbon filter: The solution is to regularly monitor the effluent quality of activated carbon, inspect the operation performance of the activated carbon filter, and carry out replacement or regeneration in a timely manner.