tagasipesu

Tagasipesu, commonly translated as backwash, is a cleaning procedure used in water filtration systems to remove accumulated solids from filter media by reversing the direction of flow. It is widely used in municipal water treatment, swimming pool filtration, and various industrial filtration setups.

In a backwash cycle, the filter valve is shifted to a backwash position, causing water to flow upward through the filter media rather than downward. This reversed flow lifts and expands the media bed, loosening trapped particles and carrying them out of the filter through a waste line. Some systems employ an air scour or air washing step to further loosen fine material before the backwash discharge.

Backwash is typically triggered by an increase in differential pressure across the filter or by a scheduled interval determined by the filter control system. The duration of a backwash depends on the filter type and water quality, and is often followed by a rinse or air purge to settle the media and restore proper filtration characteristics. After these steps, normal filtration resumes.

Backwashing is most common with gravity or pressurized sand and multimedia filters. Cartridge filters are generally cleaned by other methods and are not typically backwashed. The process generates backwash wastewater that contains solids and contaminants, requiring proper disposal or treatment to prevent environmental impact. Properly implemented backwashing helps maintain filtration efficiency and prolongs filter life.