Tech & Tools

Technical information


Filter media, which is the heart of producing safe tap water, gradually becomes contaminated with long-term use. In addition, the filtered gravel becomes a [non-land] state of gravel whose surface becomes uneven due to repeated cleaning.

With long-term use, mudballs (SS lumps) are formed in the filtration layer, and water is formed, and the filtration gravel at the bottom is spouting out.

Reasons for the non-landing phenomenon of filter media (example)
By repeating a series of states as shown in the figure below, water is gradually formed over several places, and madball formation and non-landing phenomenon occur. In addition to this, water may be formed due to defects (clogging / damage) in the lower water collecting part, and a non-landing phenomenon may occur.

  • (1) Initial stage
  • (2) Long-term use (accumulation of SS, precursor of madball)
  • (3) During water flow (water streaks are formed and raw water SS is concentrated)
  • (4) Backwashing (creating water lines, blowing up supporting gravel)
  • (5) Initial stage
  • (6) This is the result of repeated backwashing and water flow.

About the possible harmful effects of the non-land phenomenon

Decrease in filtration capacity
● The original effective area of the filter is reduced and the filtration capacity is reduced.
● Water concentrates on the part with low filtration resistance, and the raw water slips through without being treated.
● The time during which the differential pressure rises becomes shorter, and the quality of treated water cannot be maintained unless the frequency of backwashing is increased.
● Outflow of filter media

Effect of filter body
● If the supporting gravel layer collapses and reaches the lower water collecting device, the water collecting device will be clogged, causing damage to the water collecting device and outflow of filter media to the treated water side.
● Destruction of water collector


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