Sign in
FAQ
  • What matters need attention in the collection of circulating water samples?
    The representativeness of sampling is directly related to the reliability of data. The sampling container should be a hard glass bottle or plastic bottle to avoid introducing impurities from other containers (iron containers will affect the determination of iron). The sampling location should be a place with water flow, and the sampling depth should be 10cm under the water surface. The sampling point should avoid areas with foam and impurities on the surface (which will affect the determination of COD).
  • What problems need attention in the first on-site membrane cleaning service?

    Communicate fully with the customer's professional engineers or technical personnel to understand the customer's cleaning requirements, and indirectly find out the system operation and cleaning status (e.g., cleaning cycle, name of cleaning chemicals used, cleaning time control, chemical dosage for cleaning, pH control, heating status of the chemical tank, etc.).

    Understand the system operation parameters and judge the system operation status from the parameters (e.g., service life of membrane elements, system pressure difference, flow rate, desalination rate, etc.).

    If the membrane elements have a long service life and serious performance degradation, the first set of cleaning should be tentative. Minimize the contact time between chemicals and membrane elements, and the soaking time should not be too long (generally about 2 hours). The cleaning temperature and pH should be controlled within the cleaning requirements of membrane elements. The subsequent cleaning shall refer to the results of the first set of cleaning to consider whether to adjust the cleaning method.

  • What are the impacts of excessive addition of reducing agent on reverse osmosis operation?
    Sodium bisulfite can react with oxygen in the reverse osmosis feed water, resulting in a decrease in dissolved oxygen in water and the formation of an anaerobic environment. In addition, the temperature provided by the reverse osmosis feed water is suitable, which will lead to the massive reproduction of sulfate-reducing bacteria with excess sodium bisulfite and sulfate in water as raw materials, thus causing fouling of the reverse osmosis system.
  • What are the causes of abnormal increase in conductivity of reverse osmosis product water?
    Oxidation (e.g., residual chlorine) will directly damage the membrane structure.
    Insufficient operating pressure: Pressure lower than the design value will lead to a decrease in desalination rate.
    Excessively high recovery rate: Exceeding the design recovery rate will increase the ion concentration on the concentrated water side and lead to increased permeation.
    Abnormal temperature: For every 1℃ increase in water temperature, the water production increases by 3%, but the desalination rate decreases slightly.
    Sealing problems: Aging or damage of O-rings at both ends of the membrane shell will cause raw water to short-circuit into the product water side, resulting in a sudden and large fluctuation of conductivity in product water.
    Back pressure: Back pressure will cause deformation or even rupture of membrane sheets, leading to an increase in conductivity of product water.
  • What are the possible causes of the decrease in reverse osmosis water production?

    Membrane fouling (organic matter, microorganisms, colloids, etc.).

    Membrane scaling (carbonate, sulfate, silicate, etc.).

    Too low feed water temperature (for every 1℃ decrease in temperature, water production decreases by 2%-3%).

    Insufficient feed water pressure or decreased pump efficiency.

  • Why is sodium bisulfite effective in cleaning iron pollution in RO systems?
    The main reason lies in its chemical properties and cleaning mechanism. Sodium bisulfite can provide sulfite ions in aqueous solution, which have strong reducibility and can reduce iron oxides (e.g., rust) into a soluble form, thus effectively removing iron pollution.
    Reasons for its excellent cleaning effect:
    Reducibility: Sulfite ions of sodium bisulfite can react with iron oxides and reduce them to a water-soluble state.
    Easy operation: The iron pollutants can be cleaned only by introducing sodium bisulfite solution into the contaminated system and conducting appropriate soaking and circulation.
    Relatively low cost: Compared with other chemical cleaning agents, sodium bisulfite has lower cost and high efficiency.