The Key to Saving Water is in Your Backwash System

Since airwash was first introduced into filters in the 1960s, it has been widely known that the introduction of air with water achieves greater media cleansing and promotes optimum performance of granular water filters.

Simul-Wash™ is a simultaneous air and water backwash system. The Simul-Wash cycle consists of four steps: draindown, combined air/water backwash, air purge, and restratification. The key to the process is the combined air/water step. During this step, air and water at sub-fluidized rates are simultaneously introduced to set up within the filter bed a condition called “collapse-pulsing” cleaning. The agitation causes a unique scouring action in which media particles collide, breaking apart any attached solids. At these low air and sub-fluidization water rates, air bubbles form, collapse and re-form during their travel to the surface. The repetitive formation of expanding air bubbles creates outward pressure, optimizing media particle contact and abrasion in a sub-fluidized backwash procedure. Suspended solids and media are carried by the air and water up to the surface into the backwash trough area. To prevent media loss, the baffled trough creates an area free of air bubbles where media particles settle out of the backwash wastewater and return to the bed. Due to its unique shape, the Simul-Wash trough has exceptional hydraulic capacity. Consequently, fewer troughs may be required in a typical installation, therefore reducing costs.

Other manufacturers’ combined air/water backwash systems rely on the freeboard distance between filter media and the backwash trough. Thus, they are typically limited to less than 2 minutes of air/water cycle before the airwash blower must be de-energized to avoid media loss. However, our proprietary baffled trough design allows an unlimited duration of the combined air/water backwash cycle without media loss. This major difference allows extended “collapse-pulsing” cleaning cycles to more fully clean the bed, maximizing cleaning efficiency while minimizing backwash waste.

Washwater Consumption
Washwater Consumption

Hydraulic wash only at 15 gpm/ft2 for 15 minutes

Washwater volume = (15 gpm/ft2) = 22,500 gallons per wash

Simul-Wash with air at 3 cfm/ft2 and water at 5 gpm/ft2 for 12 minutes

Hydraulic wash at 15 gpm/ft2 for 3 minutes for media re-stratification

Washwater volume = (5 gpm/ft2) (12 min) (100 ft2) + (15 gpm/ft2) (3 min) (100 ft2)
= 10,500 gallons per wash


***Actual washwater savings will vary based on temperature, filter media and water quality. Calculations for a specific application are available upon request.

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