What is the purpose of backwashing? What is the backwash intensity of a filter?
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What is the purpose of backwashing? What is the backwash intensity of a filter?
The purpose of backwashing is to clean the filter media so that a new cycle of operation can begin. Backwashing intensity refers to the amount of flushing medium (usually water or compressed air) used per unit time per 1 m2 of filtration area. The unit is L/m2·S. To achieve backwashing effects, sufficient backwashing intensity and time are required. Excessive backwashing intensity can easily lead to the loss of filter media, and the water distribution devices in the filter tank are also prone to damage ； If the backwashing intensity is too low, it is not possible to remove the impurities from the filter layer completely. As a result, these accumulated impurities cause the filter media particles to stick together, leading to \"caking\" of the filter media and thus affecting the proper operation of the filter tank.
The purpose of backwashing is to separate the substances trapped by filtration from the filter media, thereby restoring the filtering capacity of the filter media. The backwashing intensity can be understood in this way: the greater the flow rate of the backwashing pump, the higher the hydraulic shear force during backwashing, which results in the filter media being cleaned more quickly and thoroughly; conversely, the opposite is true. Backwash intensity refers to the volume of backwash water flowing per unit time per unit area of filter media, measured in L/(s*m2).