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LemTec™ Recirculating Sand Filter

With this granular media filtration system, LET delivers the best tertiary filtration for efficient nutrient removal, continuously operating without a need for backwash cycles.

The LemTec™ Recirculating Sand Filter is a dynamic up-flow bed filter used for tertiary, enhanced treatment of water and wastewater to ensure the maximum removal of suspended and colloidal solids is achieved even at varying flow rates. Within the recirculating sand filter tank, influent water is distributed evenly to the media bed near the bottom of the filter before traveling upward through the filter media. A turbulent upward current brings the water into an airlift that effectively scrubs and separates the sand, captures solids and the remaining high quality filtrate.

The LET sand filter is an effective stand-alone solution and can easily integrate as a component of a custom-designed LET wastewater treatment process. The sand filter is guaranteed to deliver maximum denitrification, algae and phosphorus removal to ensure successful treatment of wastewater of all kinds, including toxic industrial waste.

Each LET wastewater treatment process and related technology, including our LET Recirculating Sand Filter, is custom designed and integrated into treatment processes with our Advanced Integrated Lagoon Technologies (AILT) approach. The AILT approach allows us to integrate cutting edge technologies, such as our sand filter, in combination with over 30 years’ proven experience to deliver guaranteed results that meet each of our clients’ unique needs.

Recirculating Sand Filter

Granular media filtration system delivers the best tertiary filtration for efficient nutrient removal

LET’s recirculating sand filter technology provides a continuous supply of filter water without interruptions for backwash cleaning cycles, delivering maximum treatment as efficiently as possible. The design of the LET sand filter allows the majority of the captured solids to remain in the lower portion of the filter for easy, quick removal. Additionally, this optimized design allows for water to be gravity or pump fed with a low pressure drop that’s typically less than 24” during normal operation. Because of this, the LET Recirculating Sand Filter is able to minimize energy consumption and operating costs while achieving optimal treatment levels.

Our advanced sand filter technology has no moving parts, requiring minimal operator attention or maintenance. It is capable of handling high loading capacities and accommodates upstream upsets to continually maximize treatment. The cutting-edge LET Recirculating Sand Filter is unsurpassed in its ability to meet the treatment objectives, delivering guaranteed results and meeting effluent limits expeditiously and cost-effectively, whether as an add-on to an existing mechanical or biological treatment plant, or when integrated into an LET wastewater treatment process design


LET is committed to continuously advancing wastewater treatment processes and related technologies, including the LET Recirculating Sand Filter. We do this by continuously improving and expanding upon our treatment designs and service offerings. Our “Circle of Innovation” philosophy ensures that the needs of our clients are met efficiently, effectively and cost-consciously as we work together with our municipal and industrial clients, protecting water resources now and for future generations.

“It has been a pleasure to work with Lemna Environmental Technologies, Inc. The service and support are fast and friendly.”

P. V., Wisconsin – LET Client

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