Lake Apopka Phosphorous Removal Pilot Project Appears Promising

from the Daily Commercial
A pilot project to remove phosphorus from Lake Apopka is one of several that may prove beneficial to restoring the lake in the next decade, according to state Sen. Alan Hays, R-Umatilla.

“We are having good results, and we are learning a lot and are still searching for the best method or the best combination of methods to clean up (Lake Apopka),” Hays said. “It is highly unlikely there will be one single methodology that works out there. But once we settle the method of cleanup it is a matter of time. A 10-year timeline is not out of the question.”

The state’s fourth largest lake previously was a “world-class bass fishery but impacts to the lake over many decades led to the lake to be named Florida’s most polluted large lake,” the St. Johns River Water Management District reported.

Lake Apopka is located south of State Road 48 — two thirds in Orange County and a third in Lake County. It is best known as the headwaters of the Harris Chain of Lakes.
The decline of Lake Apopka can be traced to “the loss of 20,000 acres of wetlands along the lake’s north shore to farming operations beginning in the 1940s; agricultural discharges laden with phosphorus until the late 1990s; treated wastewater discharges from shoreline communities prior to the 1980s; and discharge from citrus processing plants prior to the 1980s,” according to the St. Johns River Water Management District.
In early October, Ferthaul Florida RS, the contractor, kicked off the pilot project that involves dredging water from the bottom, separating the solids from the water using a parabolic filter and treating the water with enhanced cavitation, according to information on the project. Cavitation is the formation of bubbles in a liquid, typically by movement of a propeller, according to its definition.
Bill Hooper, president of Ferthaul Florida RS, said cavitation “produces heat, which will kill the bacteria.”
“When the cavitation event implodes on itself, it produces a violent shockwave, resulting in extreme heat and therefore killing the bacteria,” Hooper said. “We are doing it with water and not using any chemicals. We end up with water that is actually clean. You can actually drink it. We are capable of removing in a day what takes most people a year to do.”
After the cavitation procedure is completed, the phosphorus is then separated from the treated water in holding tanks and the phosphorus water and mud is then applied on an adjacent test site to measure the impact on vegetation growth.
Based on independent laboratory results for the first 3.5 million gallons of “processed dredged canal water and mud, the system has removed over 2,000 pounds of phosphorus from the canal.”
Hays said the cost for the phosphorus removal through this pilot project — $80 a pound — is “considerably more economical than anything else we have looked at.”
Lake County Commission Chairman Sean Parks said the project could be a game changer for Lake County.
“I applaud Sen. Hays’ effort to clean up Lake Apopka,” Parks said. “If we can get this cleaned up, the sky’s the limit when it comes to ecotourism and recreational opportunities for Lake County.”
While encouraged by efforts to clean up phosphorus from Lake Apopka, Skip Goerner, chairman of the Harris Chain of Lakes Restoration Council, said it is only one piece of the puzzle to restoring the lake as a whole.
Goerner said there are no efforts being made to reconnect the North Shore marsh to Lake Apopka.
“The marsh is essential to the restoration of Lake Apopka,” he said. “The marsh acts as a natural kidney. It slows down the surface flow of water from rainfall and it allows the water to clarify itself. We are now up to 60 billions of gallons of water per year that is never returning.”
But Ed Garland, public communications coordinator for the St. Johns River Water Management District, wrote in an email that “reconnecting the marshes would prevent the district from properly managing water levels in different areas of the North Shore, and a reconnection could potentially expose Lake Apopka to higher nutrient/pesticide levels.”
Hays said water remains one of the most prominent issues in the 2016 Legislative session.
“We will pass a water bill, and it will go to the governor, and I am confident he will sign it before the session ends,” he said.

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