Algal Turf Scrubber® technology can be designed and operated to meet a wide range of nitrogen reduction goals. ATS systems have been applied to surface water, agricultural runoff, and domestic wastewater with total nitrogen concentrations ranging from approximately 1 to 18 parts per million (ppm).
Whether the treatment objective is nitrogen load reduction to support TMDL compliance or reduction of wastewater discharge concentrations below Advanced Wastewater Treatment (AWT) standards, ATS systems can be configured to address demanding water quality goals.
ATS systems are designed to operate at high hydraulic loading rates while maintaining active attached algal growth and routine biomass harvesting. Across a range of point and nonpoint source applications, annual nitrogen removal rates have ranged from approximately 500 to more than 8,000 pounds of nitrogen per process acre, depending on source-water quality, climate, hydraulic loading, harvest frequency, and treatment objectives.
Annual nitrogen removal rates of more than 6,400 pounds per acre of treatment area have been achieved while treating stormwater runoff in the Lake Okeechobee watershed. Under comparable low nitrogen inflow concentrations, ATS systems have demonstrated nitrogen removal per acre more than 200 times greater than large constructed treatment wetlands.
Nitrogen reduction at low influent concentrations can be especially important for surface-water restoration, stormwater treatment, water reuse, and advanced wastewater polishing applications. Full-scale facilities such as Osprey Marsh ATS provide operating references for nutrient polishing where the objective is not simply bulk nutrient removal, but sustained reduction toward low receiving-water nutrient concentrations.
S-154 ATS testing showed higher nitrogen areal removal rates at higher Linear Hydraulic Loading Rates (LHLR) while treating low-concentration stormwater with mean influent TN of approximately 1.85 mg/L. LHLR is expressed as gallons per minute per linear foot of ATS floway width (gpm/lf).