If you ask anyone in the environmental science world about water quality, you’ll hear this: In order to avoid crises like last summer’s red tide and blue-green algae eruptions, you’ve got to keep nutrients out of our rivers, streams, canals and shoreline. The more those substances, namely nitrogen and phosphorous, infiltrate the water, the bigger your algae bloom might grow.
“It’s very important that when we are trying to address this issue we understand that prevention is always cheaper than treatment,” says Jennifer Hecker, executive director of the Charlotte Harbor National Estuary Program. “The most cost-effective and efficient way of removing nutrients from our waterways is just keeping them out of there to begin with.”
Alas, Florida—the state that’s 18.5 percent water and boasts the longest coastline in the lower 48—has not figured out how to prevent dirty runoff from contaminating water bodies. Until such regulatory matters are worked out, scientists and science-minded entrepreneurs are looking for the next-best thing: how to clean up algae-infested water.
Lots of companies are visiting or setting up shop in the Sunshine State to test out various purification systems. We examined a few of the ones that are addressing cyanobacteria, the blue-green algae found in fresh or brackish water. Many zeroed in on Cape Coral—that city of canals—and so we turned our attention there, too, learning about methodologies tried and the ensuing results, as evaluated by the region’s top water experts.
VACUUMING UP THE ALGAE
HOW IT WORKS: With approval from the Florida Department of Environmental Protection, Lee County hired California- based construction and engineering firm AECOM to vacuum up algae from county waters. The slurry removed—a mixture of algae and water—was put in a tanker and taken to the North Lee County Reverse Osmosis Plant. It was then processed to separate liquids and solids, and the solid waste went to the Lee County
Landfill in Hendry County. The liquid waste was treated to FDEP specifications, transferred into an existing five-million-gallon holding pond, then pumped into a deep-injection well 2,600 feet below ground, which the county says is below the confined drinking-water aquifer. The cleanup cost was $1.61 million.
WHAT THE EXPERTS SAY: As far as removing the algae from the water goes, this method worked. “That project was very successful,” says Jeff Pearson, utilities director for the City of Cape Coral. “We were able to eliminate all of the thick algae mats that had built up in dead-end canals.”
But others see it as an expensive option that comes with some concerns. “It does physically remove the material from the ecosystem, which helps,” says Hecker. “But the waste stream aspect was a bit of a challenge.”
John Cassani from Calusa Waterkeeper, a nonprofit focused on the protection of local waterways, is concerned about potential public health risks that could arise from the chosen disposal methods, due to the fact that the algae produces microcystins, toxins that could be carcinogenic. “We’re still trying to follow up with FDEP on that one to try to understand where they got their protocol,” he says. “It’s been an uphill battle.”
HOW IT WORKS: Used previously to clean up after events like the BP Oil Spill, AquaFlex’s open-cell foam membrane traps water contaminants and works something like the human lungs, absorbing contamination and releasing clean water. People might be familiar with closed-cell foam from things like yoga mats or running shoes. With AquaFlex’s open-cell foam, those closed cells are burst open through a special process, which creates an open-cell capillary-connected network that functions like the tiny air sacs called alveoli in the human lungs and expands the surface area to maximize the foam’s direct contact with contaminated water. AquaFlex uses a medical-grade polymer to create a variety of flexible designs and shapes to optimize performance, such as “curtains” resembling eel grass or mats.
The Massachusetts-based company tested the product in the Fort Myers area (in conjunction with a team that included the Charlotte Harbor National Estuary Program, Sea and Shoreline, and marine science professor Michael Parsons from Florida Gulf Coast University) and results looked promising. In all nine configurations tested, absorption rates ranged from 45,000 ppb (parts per billion) to 259,000 ppb. For other water contamination disasters, a yield of more than 1,000 ppb is considered significant.
AquaFlex can be wrung out and re-used for situations like oil spills. But for blue-green algae, that’s not the best approach because of the toxins the algae produce. “This poses some unique challenges to ensure maximum protection from the impact on human health and making sure that the contamination is not moving from one body of water to another and/or into a landfill,” says Scott Smith, founder of AquaFlex.
Smith’s approach? AquaFlex products that are fully saturated with blue-green algae should get removed and transported to a waste-to-energy facility. In the case of the product testing done in Lee County, the waste all went to GreenWater Laboratories in Palatka, Florida, for analysis of how effective the technology was at removing blue-green algae from the water.
But Smith says the ability for the waste to be processed and destroyed at a waste-to-energy facility is a major plus of his technology. “That’s a very big deal about what we’re doing,” says Smith. “We’ve got the ‘How do you dispose of it?’ piece solved in a very environmentally responsible way.” As he works to scale up the product for use in algae outbreaks, he’s particularly looking at facilities that use plasma-arc technology, since there is no formation of ash and the process breaks waste material down into atoms that recombine into harmless gases.
WHAT THE EXPERTS SAY: Hecker says the initial tests showed it was effective and hopes to a do a larger study to expand on the results. “I think it could be a promising technology,” she says. “The mats are affordable and could be easily stored in different locations. The idea would be to attack the problem when it’s small; it would be difficult to use on a very large scale. But a lot of times these start as small outbreaks at the end of a canal where it is relatively contained. That’s when it’s easier to use these types of technology that could treat it before it spreads.”
Cassani agrees that it’s a potential solution that seems best-suited for small areas, not bigger outbreak zones. “Does it work on a scale that’s the scale of the problem?” he asks. “At one point Lake Okeechobee had easily 400,000 acres of cyanobacteria. So how is that going to scale up?”
MICROORGANISMS THAT ATTACK THE ALGAE
HOW IT WORKS: New York-based Ecological Laboratories, whose production and R&D facility is in Cape Coral, treated a controlled section of Cabot Canal in Cape Coral. Microbe-Lift, the company’s combination of naturally occurring microorganisms, not only kills off the algae without any chemicals but also removes nitrates from the water through a process called anoxic respiration. That’s a key element, because if nitrates simply die off but aren’t removed, those nutrients remain in the water, ready to provide fuel for future algae outbreaks.
During its trial period, the company saw no negative impacts to other aquatic life in the canal and in fact reported “active aquatic marine life” and the return of birds to the treated area. Improvements to the canal were seen both visually and through lab measurements, which showed reductions in levels of ammonia, nitrite, nitrate and phosphate.
Microbe-Lift has been used in Petco stores for 12 years to keep aquariums clean and has also been used to treat ponds, lakes, and rivers around the world. “In Jacksonville, we’ve used it on an eight-lake series of brackish water for 12 years,” says Doug Dent, vice president of sales for Ecological Laboratories. “With no chemical usage whatsoever we’ve restored that ecosystem. We’ve cleaned up the solids on the bottoms [of the lakes] that create odors and result in fish kills.”
WHAT THE EXPERTS SAY: Pearson likes what he has seen so far. “The results are still preliminary and we’re going to continue to evaluate it,” he says. “But from what we’ve observed it looks like it did work. But I don’t want to say 100 percent it’s the solution until we have all our data in. But we actually saw a lot of marine life thriving in that area, versus the area outside of the test area. So what we saw was very positive and encouraging.”
Cassani has some questions about the general process, though. “It’s my understanding that it requires subsequent applications,” he says. “It may not be cost-effective to scale up to thousands of acres. Scale of application is important when considering applicability.”
NANO BUBBLES/BUBBLE CURTAIN
NABAS GROUP/VERTEX WATER FEATURES
HOW IT WORKS: Through an aeration system, nano bubbles less than 5 microns in diameter (about the size of a human red blood cell) deliver oxygen and/or ozone into the water to disinfect it and break up any bacteria or fungus in the water. No chemicals are used in the process of increasing the dissolved oxygen in the water. Maryland- based NABAS Group has used this process to treat lakes in Mount Pleasant, South Carolina and Fort Myers at Lexington Country Club. In October it began a project in a Cape Coral canal off Del Prado Boulevard that was cut short due to Hurricane Michael. But four days of data collection showed increases in dissolved oxygen levels.
Also in October, Vertex Water Features of Pompano Beach installed its AirGate bubble curtain system across the mouth of the Mandolin Canal in Cape Coral to block cyanobacteria in the Caloosahatchee River from entering the canal. A 12-horsepower compressor system pushed air through hoses into 44 membrane bubble diffusers that were lined up across the bottom of the canal’s entrance, with the goal of forming a wall of bubbles. That wall would ideally create large boils of outward flowing water with the kinetic energy needed to deflect and push away any floating cyanobacteria attempting to enter the canal.
WHAT THE EXPERTS SAY: These tests did not produce a lot of enthusiasm. According to Pearson, by the time the Vertex bubble curtain was installed, there wasn’t a lot of blue-green algae around to test its effectiveness. “We were able to use sawdust and a stormwater tracer dye, and it appeared on the surface to do good job at keeping it back,” he says. But what’s still unclear is whether it would have any impact on submerged materials. Pearson says the city may do further tests next year to get more data if it feels it’s needed.
Hecker isn’t intimately familiar with either of these trials. But she says the general concept of infusing oxygen into water can create conditions that are better for aquatic life and less conducive for growth of harmful algae. The problem? “You’re not physically removing nutrients,” she says. “And if the nutrients aren’t physically removed, they can become a fuel source for future outbreaks. This goes back to the root issue of finding solutions that stop the cause rather than just treat the illness.”