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Thread: Dual filter backwash

  1. #1
    New Member
    Join Date
    May 2023

    Dual filter backwash

    Hallo everyone
    in case of a gravity dual filter, eg sand and anthracite, is a combined air & water wash cycle advisable? What velocities can be applied?
    Water process and operations

  2. #2
    Join Date
    Aug 2023
    When considering a gravity dual filter system with sand and anthracite media, the use of a combined air and water wash cycle can be beneficial in certain situations. Let's explore the concept and considerations:

    Combined Air & Water Wash Cycle: Combining air and water in the backwash cycle can enhance the efficiency of filter media cleaning. The introduction of air can help loosen and lift trapped particles from the media bed, allowing the subsequent water flow to carry them away. This can lead to a more thorough cleaning process compared to using water alone.


    Improved particle removal: Air agitation can dislodge particles that might be tightly bound to the media.
    Reduced media compaction: Air helps prevent media compaction, which can prolong the life of the media bed.
    Enhanced backwash efficiency: Air-water combination can create turbulence, enhancing the effectiveness of the backwash process.

    Equipment compatibility: Ensure that your filter system is designed to handle both air and water in the backwash cycle.
    Media type: The effectiveness of air-water backwash can vary depending on the specific media used (sand, anthracite, etc.).
    Operating conditions: Proper flow rates and pressures must be maintained to ensure effective backwash without damaging the media.
    Velocities: Optimal velocities for the air and water backwash cycles can vary based on factors such as media size, bed depth, and filter design. Generally, velocities for air-water backwash are lower than those used during filtration to avoid media scouring and fluidization.

    It's recommended to consult the manufacturer's guidelines for your specific gravity dual filter system and media types to determine the most suitable velocities for the combined air and water backwash cycle.

    As always, conducting pilot tests or consulting with experts in water process and operations can provide valuable insights tailored to your system's parameters and goals. Balancing the benefits of a combined air-water backwash with the practical considerations of your specific setup will help you optimize the performance of your gravity dual filter system.

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