In Tampa, the city’s water department is harnessing ultrasonic technology to tackle algae growth in the Hillsborough River, enabling it to reduce its reliance on chemical treatments for drinking water.
The city recently wrapped a two-year pilot project deploying ultrasonic buoys developed by LG Sonic to disrupt algae formation in the river and collect water quality data. The results? Fewer chemicals and smarter water monitoring.
“The ultrasonic buoys send out ultrasonic sound — a high frequency — across the surface of the water,” Tampa Water Production Manager John Ring said. “It goes out 500 feet from the buoy and will prevent algae from floating up to the water’s surface where they use sunlight to proliferate and reproduce. That will knock them back down in the water column where they will wither and die.”
The ultrasonic buoys are equipped with smart sensors that continuously monitor water quality and transmit data to the company’s cloud dashboard. The buoys monitor the water’s acidity level, dissolved oxygen and turbidity levels, and chlorophyll and cyanobacteria, which gives the water department “kind of a heartbeat,” Ring said, of what's going on with the algae around the buoys.
“What’s nice about the buoys is they’re giving us real-time data, which is giving us a little bit more insight to just what's going on in the river as far as algae is concerned,” he said.
Tampa Water Department uses LG Sonic’s dashboards to monitor the buoys, which automatically adjust ultrasonic frequencies based on the specific algae species detected in the water. The company, Ring said, typically monitors results for about three days after changing frequencies, and if they don’t see a good reaction, they use the technology to alter the frequencies again.
“It’s like a cat-and-mouse game of chasing after the algae and changing the frequency to keep them off balance,” he said.
During the pilot, the city deployed two buoys in the Hillsborough River, one at the water intake point and another 1,000 feet upstream, to create two controlled zones.
Before introducing the buoys, staffers controlled algae growth with algaecide sprayed from boats. The shift to non-chemical technology brought cost savings and sustainability benefits.
“As far as cost-wise, we are probably saving about $100,000 in algaecide,” Ring said. “For us, it was a bonus, but what was driving us to take a look at this technology was to find a more evasive way of controlling the algae without chemicals.”
The pilot was made possible through a Florida Department of Environmental Protection grant. The funding provided Tampa with a low-risk opportunity to explore new solutions that might not have been pursued otherwise, Ring said. With results in hand, the next step will be expanding from two buoys to four.
“It’s going to allow us to create a deeper field of ultrasonics along that river so we can impact the algae even further,” Ring said.
The pilot, a 90-day program in partnership with tech company 374Water, began recently to test an advanced treatment process at a city water reclamation facility. The company’s AirSCWO system leverages supercritical water oxidation (SCWO) technology, a process that uses intense heat and pressure to fully break down organic compounds, leaving behind only water and inorganic salts — and doing away with contaminants.
But beyond those targets, the technology is being tested as a potential solution to one of Orlando’s biggest wastewater challenges: sludge disposal.
Corey Knight, the city’s director of Public Works, outlined the reasoning behind piloting the new technology.
“Through our water reclamation process, we are left with sludge that we still need to dispose of. With this pilot test, the main goal is to see if the SCWO unit can treat enough sludge to be in continual use, allowing us to reduce the amount of byproduct and create a more sustainable process,” he said.
The city is currently evaluating whether the system can reliably handle more than 30 wet tons of sludge per day. So far, preliminary results from 374Water show the technology can destroy per- and polyfluoroalkyl substances (PFAS) contaminants at rates exceeding 99.9 percent for all tested materials. That level of destruction, if proven consistent, Knight said, could mark a significant breakthrough in how cities nationwide tackle some of the most persistent and hazardous pollutants in their water.
The public works director said he sees the pilot, which was funded by the U.S. Environmental Protection Agency (EPA), as more than just a local sustainability initiative but a potential model to advance water treatment nationwide. If successful, Ring said he believes the program has the potential to help guide EPA research priorities and inform future investments in next-generation wastewater technologies.
“Public Works wants to help not only the city, but our wastewater treatment industry as a whole,” he said. “EPA is concerned with PFAS and other emerging contaminants, and new technology to address these in the future. By working together, we can help further treatment and expand research.”
