The underdrain is the heart of every granular media filter. A well designed underdrain is durable and efficient, the filter will provide many years of continuous service.

EWT filter underdrains provide a durable, corrosion resistant system for collecting filtered effluent and accurately metering uniform air + water backwash flows. Innovative design features eliminate the two flow problems that have plagued other combined air + water cleaning systems: improper sizing of variable diameter orifices, and media displacement by surging or irregular flows.

EWT underdrains feature lateral ducts constructed of stainless steel, axially partitioned into channels for air and water. A variety of feed and drainage arrangements are possible, depending on existing basin layout and piping. All distribution orifices are specifically sized for each application to ensure flow equalization.

BACKWASH TROUGHS

ScourGuard™ filter backwash troughs allow granular media filters to be cleaned by simultaneous application of air scour and water backwash, with minimal media loss in the backwash waste. Concurrent application of air scour and backwash waster is an aggressive media cleaning technique that allows tenacious, deeply embedded contaminants to be removed quickly and efficiently.

The technique offers real operating economies through reductions in backwash frequency, backwash water production, and lower energy consumption of air blowers and backwash pumps; however, media loss is a concern. When backwash water is allowed to overflow the trough weirs during air scour, air induced turbulence can cause media particles to be carried into the waste trough and lost.

The ScourGuard™ trough essentially eliminates media loss through the use of the patented trough baffle design.