I. Replacement cycle under normal operating conditions (suitable for most scenarios)
For scenarios where the influent turbidity is ≤10 NTU (such as municipal water or circulating water replenishment), there are no sticky impurities or hard objects, and regular backwashing and screening maintenance are required, the filter media lifespan can reach 4-5 years.
In these scenarios, the filter media wears out slowly and clogs less. Regularly replenishing a small amount of lost or broken filter media is sufficient to maintain the filtration effect, without the need for complete replacement.
II. Replacement cycle under special operating conditions (replacement time needs to be shortened)
The influent turbidity is often >10 NTU (such as river water or lightly polluted water), contains a large amount of sticky impurities or small hard objects (such as slag particles), and the filter media is prone to wear and caking, so the replacement cycle needs to be shortened to 2-3 years.
If the ultrafiltration rate (>50m/h) is operated for a long time, or if the backwash intensity is too high, the filter media will break down and be lost more quickly, and the replacement cycle will need to be brought forward by 6-12 months.
III. Visual Criteria for Determining When Filter Media Needs Replacement
Decreased filtration efficiency: The turbidity of the effluent is consistently >5 NTU, or the suspended solids removal rate is less than 70%, and there is no improvement even after optimizing backwash parameters and adding filter aids.
Abnormal filter media condition: After screening, more than 30% of the filter media is found to be broken or pulverized, or the filter layer thickness is significantly reduced (below 100mm), and the condition cannot be stabilized even after adding new filter media.
Abnormal operating resistance: The pressure difference between the inlet and outlet rises too quickly, and the pressure difference still cannot fall back to 0.01-0.02MPa after backwashing, indicating that the filter media is severely clogged and cannot be restored by backwashing.
IV. Maintenance measures to extend the life of filter media
Regular screening: Every 6-12 months, remove the filter media and screen it to remove broken particles and impurities, and add new filter media of the same specification to maintain the stability of the filter layer gradation.
Chemical cleaning: Every 3-6 months, rinse the filter media with dilute hydrochloric acid or citric acid solution to remove surface scale and stubborn organic matter, and restore the filter media's adsorption capacity.
Source control of pollution: In scenarios where the turbidity of the influent exceeds the standard, pre-treatment (such as a coarse filter) is added to reduce the retention pressure of the filter media and reduce the wear and clogging speed.
