Filter Underdrains

Benefit from Enviroquip's years of experience in folded plate underdrain air scour systems with the improved media retaining design. This new design follows years of proven performance of the folded plate underdrains providing uniform distribution in low headloss gravity backwash systems and filter retrofits with pumped backwash systems.

Media retaining underdrain eliminates support gravel. The 0.25mm wide punched openings allow the filter media to sit directly on the underdrain and air scour laterals. Low profile design, 6 to 8 inch vertical height, and no support gravel allows deeper media stacks than previously considered with other underdrain designs.

Uniform introduction of air and water through separate conduits provides superior simultaneous air/water backwash. Simultaneous air/water cleaning of the filter is done over a short time period with low waterwash/ air rates resulting in reduced volume of wash water usage.

Separate uniform distribution of air and water provides the vigorous agitation required for effective media cleaning. Most other systems introduce air and water through the same orifices creating a surging action and non-uniform distribution of air and water resulting in irregular cleaning of the filter media.

STAINLESS STEEL FOLDED PLATE FILTER UNDERDRAIN/AIR SCOUR SYSTEM

Strong and Permanent
Stainless steel construction, 12 or 14-gauge stainless steel plate and 16 gauge stainless steel tube, provides long corrosion free, maintenance free life — all stainless steel components in the filter box. Epoxy capsule/stainless steel rod anchoring system provides clamping force to withstand even the highest lifting forces with substantial safety factors. Even distribution of air and water through separate conduits with minimum pressure drop. Large area formed by folded plate provides low headloss down the underdrain with water introduced through 3/16" diameter orifices spaced approximately 2" on center. Air is introduced through 3/16" diameter orifices evenly spaced along both sides of the rectangular laterals.

Air Scour
Uniform cleaning of the filter media with auxiliary air scour and water wash is essential for peak filter performance. Enviroquip's air scour and underdrain system provides this uniform cleaning whether as separate operations or simultaneous air/water. Separate air/water conduits eliminates opportunity for blowouts. The overall efficiency of our air scour system is evident by the lower air scour rates utilized. Lower air rates means reduced blower and piping costs and lower long term operating costs. Air is introduced at the lowest point in the valley between folded plates for best scouring of the media layer prior to media fluidization. Air is introduced above the underdrain eliminating the possibility of high pressures when compressible air and non-compressible liquid are mixed.

Simultaneous Air/Water
Separate air and water conduits is the best design on the market for simultaneous air/water backwash. Uniform distribution of air and water is virtually instantaneous. The combination of air scour and water wash reduces the amount of backwash water required to clean a filter. This is a major benefit for most facilities because not only is less water wasted with each backwash, increasing plant throughput, but the lower volume of backwash waste means downstream facilities (decant thickeners, holding ponds, pumps, etc.) that deal with this waste do not have to be expanded. Enviroquip's simultaneous air/water cleaning eliminates the problem other designs have with media loss. In fact, media loss of less than 1" over a 5-year period is common.

Folded plate underdrains, air scour laterals and stainless steel backwash troughs.
Air scour manifold and air feed pipe to each lateral
Existing header lateral underdrains in 20' x 42' filter cell prior to retrofit.
New stainless steel folded plate underdrains with air scour piping in same 20' x 42' filter cell after retrofit.

Simple Installation
Contractors verify our system as the lowest installation cost of any system on the market.

Underdrains, air scour laterals, anchors and manifold pipe are simple to install and do not require critical leveling or grouting to perform as designed. Epoxy capsule anchors spaced on maximum 24" centers provides clamping force to seal underdrains to the filter floor.

Ideal for Retrofits
Fabricated construction makes it the ideal system for filter retrofits; clay tile blocks, wheeler bottoms, header laterals and walker camp nozzles have been replaced with stainless steel folded plate underdrains. Low profile underdrain means more room for filter media to meet today's stringent effluent requirements. The headloss for each filter system is designed specifically for that system. Headloss is calculated based on years of filter underdrain experience to provide uniform distribution of wash water at maximum backwash rates.

Backwash Systems
The fact that we can vary the headloss through the underdrain allows us to offer underdrains for conventional pumped backwash filters or inner filter gravity backwash systems. Conventional pumped backwash filters required a higher underdrain headloss to insure uniform distribution of wash water. The principal behind inner filter backwash design is to provide a lower headloss through the underdrain and the piping to allow utilizing throughput from several filter cells to backwash an adjoining filter cell.

Proven System
Enviroquip's earliest folded plate installations date to 1981 are now provided with the improved air lateral/clamp system. Our experience is your assurance of trouble free installation and operation.