Cypress swamp regains water quality with help from SolarBee circulators
Water and Wastes Digest Case of the Week
Fri, 07/22/2011
By Patrick J. Schnaidt
Award-winning circulation technology reduces blue-green algae.
Greenfield Lake, an idyllic cypress swamp surrounded by walking paths and bridges, is a popular recreation area in Wilmington, North Carolina. Residents and visitors enjoy picnicking, gardens, an amphitheater, boating and fishing.
But when blue-green algae took over the swamp, the water turned to pea soup and weeds grew thick along the shore. The shallow, 100-acre reservoir is primarily fed by stormwater via several drainage pipes throughout the basin. Boaters preferred to go elsewhere.
To clean up the water and bring back boaters and visitors, city officials installed four SolarBee SB10000v12 units that provide long-distance, near-laminar flow. The solar-powered, floating circulators operate day and night with a low-voltage motor and on-board battery system for continuous, energy-efficient water quality improvement.
How horizontal mixing improves water quality
“Pea-soup” water is typical of stormwater ponds, reservoirs and lakes that are susceptible to unhealthy and harmful algae blooms (HABs). These large-celled blue-green algae can predominate in warm, stagnant, nutrient-rich water. An environmentally preferable alternative to chemical treatment, long-distance mixing creates enough horizontal and vertical water movement to sufficiently disrupt large-celled blue-green algae and instead allow the “good” small-celled algae to predominate.
The goal of a horizontal mixer is not to add oxygen to a reservoir. That’s the work of green algae. The purpose of a horizontal mixer is to help the good algae survive. When the good algae survive, the levels of algae, zooplankton, fish, dissolved oxygen and pH will stay in balance.
At Greenfield Lake, SolarBee circulators draw in water from all directions, pushing it upward and sending it out across the surface in a thin layer. Good green algae and diatoms are pulled up from below, lifted to the top and sent out across the surface again, where they receive sunlight and are available to zooplankton. Gentle mixing and surface renewal, which keeps green algae suspended where they can receive sunlight, allowed Greenfield Lake to return to a healthy state.
Recreational users return
Within two months of installing SolarBee circulators, Wilmington city officials reported positive comments from visitors: the lake looked better than it had in recent history. Fishermen returned and canoe rentals doubled. Greenfield Lake is now a healthy reservoir that has clearly won the battle against blue-green algae. Even alligators appear to appreciate the improvement, if not for the water quality then to soak up some rays on the SolarBee units.
About SolarBee®
SolarBee Inc., a division of Medora Environmental Inc., develops, installs and services long-distance water circulation equipment to help solve water-quality problems. The award-winning and patented long-distance circulation technology has been successfully applied to prevent and control harmful blue-green algae in fresh water, reduce energy usage and control odors in wastewater, and to reduce nitrification, thermal stratification, and stagnation in potable water storage. The floating long-distance circulators can move up to 10,000 gallons per minute from depths of more than 100 feet and have been proven in hundreds of applications worldwide. For more information, call 866-437-8076 or visit www.solarbee.com.