Protecting Human Health and Aquatic Ecosystems with Ultrasonic Technology

F elipe S. Contreras is a Principal Engineer at Kleinfelder. He specializes in integrated water resources management, water and wastewater treatment and distribution systems, efficient utility operation, and hydraulic modeling. If you’ve ever spent any time around a body of water, you’ve probably encountered areas affected by algae— simple photosynthetic organisms that live in the sea and freshwater. While algae may have disrupted your day on the lake, the impacts of algal blooms go far beyond an occasional slimy and odious inconvenience; they can actually be very harmful. 

Harmful algal blooms (HABs) occur when algaelike bacteria grow out of control while producing dangerous toxins. Warm temperatures coupled with stagnant nutrient-rich water and sunlight exposure act as a catalyst for HABs, which have become a significant environmental problem in all 50 states. In addition to posing a significant threat to human health by impacting drinking water reservoirs, HABs are detrimental to aquatic ecosystems and local economies that rely on water-related tourism. As rising carbon dioxide levels and temperatures are coupled with periods of intense precipitation, the occurrence of HABs is predicted to increase, making management, response, and research efforts related to HABs a priority. Fortunately, a relatively new technology, which uses ultrasonic waves, is proving to be very effective at controlling HABs.

"Many units in the HAB control market can send ultrasonic frequencies, however the state-ofthe-art monitoring, transmission of data and online access to the information is a game changer"

Kleinfelder— a leading engineering, science, and construction services firm—is currently using these emerging ultrasonic algae control units to support the City of Newark Department of Water and Sewer Utilities with addressing HABs that have impacted two of the five reservoirs serving the Pequannock Water Treatment Plant. The ultrasonic units have been deployed in key locations of the Echo Lake reservoir, and grab samples have been collected to verify the effectiveness of the ultrasonic units. Kleinfelder is also working closely with the manufacturer to verify and validate the equipment performance. 

The MPC (Monitor, Protect, Control) Buoy is an ultrasonic algae control unit manufactured by LG Sonic. The MPCBuoys emit an ultrasonic wave which creates a “sound barrier” near the surface of the water which serves to block algae from photosynthesizing without adverse impacts to humans, animals, fish, or other aquatic life. The MPC-Buoys are equipped to monitor water quality and algae parameters such as turbidity, pH, temperature, dissolved oxygen, chlorophyll-a, and Phycocyanin in real time to provide necessary information to enable the user to adjust the ultrasonic frequency. The specific frequency causes a disruption to the buoyancy regulation organs in Cyanobacteria, impacting the production of intracellular gas-filled structures (vacuoles). At lowlight conditions, gas-filled structures can be produced at a high rate, and cells increase their buoyancy. Conversely, if cell osmotic potential is high (during photosynthesis) cells become negatively buoyant and sink in the water column. 

Many units in the HAB control market can send ultrasonic frequencies, however the state-of-the-art monitoring, transmission of data, and online access to the information is a game changer. The units are essentially solar-powered labs that log and analyze samples and allow for fine tuning to control the algal formations. With the results displayed via the web, it’s a dream come true for engineers and scientists working to mitigate and prevent HABs.

The efficiency and effectiveness of the ultrasonic algae control units are being monitored over the course of a 36-month pilot program, which is partially funded through a New Jersey Department of Environmental Protection grant. Now after completing year one of the program, the technology is proving promising, after consecutive years of reported HABs in Echo Lake. In 2020, even after a late start (September) in the deployment of the ultrasonic control units, HABs were not observed. 

In addition to speeding up a state and/or local agency’s ability to mount a sustainable and effective emergency response to HABs, the technology can be proactively deployed in at-risk bodies of water to prevent outbreaks in the first place. While a well-planned water quality testing and data collection program will continue to be a key component to proactively preventing HABs, ultrasonic algae control units equipped with water quality monitoring technology will serve as a vital component to maintaining healthy waters and reducing risk to people, wildlife, and the environment.