Challenge
The Egret Marsh Regional Stormwater Facility is being designed to treat fertilizer-laden urban and agricultural runoff currently discharging to the Indian River Lagoon. By reducing nitrogen and phosphorus levels, HydroMentia’s ATS™ will allow the county to better meet Federal Total Maximum Daily Load (TMDL) limits for these nutrients and avoid harmful algal blooms while improving overall water quality. These improvements are one part of Indian River County’s comprehensive program to restore the Indian River Lagoon—the most biologically diverse estuary in North America.
Solution
HydroMentia’s Algal Turf Scrubber® uses algae to remove excess nitrogen and phosphorus from water. Polluted water is conveyed to the Algal Turf Scrubber®, where it is pulsed in waves across a sloped floway. Algal turf or dense mats of simple algae are cultivated on the surface. As the algae grow, they remove nutrient pollutants (nitrogen and phosphorus) from the water. The harvest of plant biomass maintains the system in an accelerated growth phase and provides sustainability as nutrients are continuously recovered and removed from the treatment unit.
Results
Hydromentia, Inc. has completed design of a 6-acre ATS™ for the Egret Marsh Stormwater Facility. The proposed ATS™ is designed to treat 10 million gallons of water per day on a 575’ floway. It is projected, based on historical water quality, that the Egret Marsh Algal Turf Scrubber® system will remove approximately 3300 pounds per year of phosphorus at an areal removal rate of 712 lbs/acre/yr (80 g m-2 yr-1), approximately 14,000 pounds per year of nitrogen at an areal removal rate of 5160 lbs/acre/yr (578 g m-2 yr-1). Project bidding and construction are scheduled for the fall of 2007.