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LemTec™ Biological Treatment Process

The LemTec Biological Treatment Process™ (LBTP) is an advanced, aerated lagoon treatment process capable of meeting some of the most stringent treatment parameters. This state of the art treatment process focuses on eliminating many of the short comings of traditional aerated lagoon processes and enhancing many of their benefits.

LET’s innovative LBTP Process achieves year-round effluent limits as low as 10 mg/L BOD, 10 mg/L TSS and 1 mg/L NH3-N, 1 mg/l Total Phosphorus and 10 mg/l Total Nitrogen at a fraction of the cost of traditional wastewater treatment systems. With a smaller footprint than traditional lagoons and lower capital and operating costs than mechanical treatment processes, the system allows for easy expandability for future needs.

Each LET wastewater treatment process, including the LBTP, is custom designed with our Advanced Integrated Lagoon Treatment (AILT) approach. The AILT approach allows us to integrate cutting edge technologies in combination with over 30 years of proven experience to deliver guaranteed results for each of our clients’ unique needs.

Stages of
The Biological Treatment Process

Stage 1
Aeration Process for Aerobic Treatment

The first stage of the the LemTec Biological Treatment Process™ (LBTP) is an aerobic process.  The aeration process design in an LBTP system consists of one to several aeration cells. The primary objective of the aeration cells is to provide consistent, reliable BOD removal and set the stage for the remaining treatment objectives. Sophisticated process modeling ensures that the aeration process is maximized, designed to perform consistently and reliably even during high flow conditions or variable influent loading. The other primary function of the aeration cells is to begin the process of sludge digestion and stabilization.

By covering the aerated portion of the LBTP process with the LemTec™ Modular Insulated Cover System, the lagoon can maintain an optimal, consistent wastewater temperature, which enhances the kinetic reaction rates for BOD removal and nitrification and increases performance reliability during transitional periods. In addition, our cover system eliminates algae and aquatic growth within the lagoon that can contribute to elevated TSS levels, negatively impacting BOD removal, and causing nuisance odors.

Stage 2
Solids Management

After the aerobic process stage of the LemTec Biological Treatment Process™ (LBTP), the next primary step is for sludge reduction and solids management including storage, separation and digestion. The first consideration is to provide an environment conducive for solids settling. The use of the LemTec™ Modular Insulated Cover enhances the settling process by eliminating wind and wave action on the lagoon surface.  

In addition, our cover system eradicates algae or aquatic growth within the lagoon and potential for nuisance odors. Our cover system also eliminates the stratification of temperatures and prevents pond “turn over” during changes in the season.  

To achieve proper sludge digestion and benthal decay, LET provides a unique aeration process within the settling zone. Doing so enhances the digestion process, minimizes the amount of sludge collected and eliminates the risk of benthal rebound. Through this unique settling design, Lemna can ensure the settling zone will be sized adequately to provide many years of maintenance free service as it relates to sludge handling.

Stage 3
Expanded and Tertiary Treatment Components for Enhanced Process Capabilities

Depending on our customers’ individual, final treatment objectives, LET is able to include additional treatment steps immediately following the custom-designed LemTec™ Biological Treatment Process (LBTP) settling zone.

The need to reduce ammonia, for instance, is quite common. The use of the Lemna Polishing Reactor™ (LPR) immediately downstream of the settling zone is used to achieve ammonia limits down to less than 1 mg/l.  The LPR is a submerged, fixed film, attached-growth process that creates an environment conducive to the growth of nitrifying bacteria necessary for ammonia removal and BOD polishing. Further nutrient removal, beyond ammonia may be required.  

The LemTec™ Phosphorus Removal System (LPRS) can be designed into our LBTP process prior to the wastewater reaching the final LPR step. The LPRS is comprised of a chemical dosing system, low horsepower pumps and mixers. The phosphorus removal process precipitates phosphorus and allows contaminants to be dissolved or suspended to settle out as floc particles, achieving effluent of 1 total phosphorus for our clients.

Other steps can be added to adapt the LBTP and enhance its capabilities to accomplish virtually any treatment objective including Total Nitrogen (TN) removal, additional solids capture, and more. With each customized LBTP design, we are able to successfully deliver wastewater treatment solutions that meet every challenge from influent to effluent.


LET is committed to advancing lagoon technologies and treatment processes, including the LemTec ™Biological Treatment Process (LBTP), 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.  

“Lemna is definitely a leader rather than a follower. The LemTec™ Biological Treatment Process has proven to be an excellent choice. The installation process is simple yet effective in its high degree of performance and low maintenance cost.”

B.L., New Hampshire – LET Client

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