Ultrasonic Sedimentation Basin Algae Control: AWWA Opflow Study Documents Chemical-Free Results

A peer-reviewed look at sedimentation basin algae control

Sedimentation basin algae control rarely reaches the technical literature. Still, it remains a routine operational headache for surface water treatment plants. A June 2026 article in AWWA Opflow changes that. Engineers at Central Alabama Water wrote it together with a researcher from the University of Alabama. The article documents a full-cycle field evaluation of an LG Sonic ultrasonic system. The system was installed to manage chronic algae growth in a working drinking water sedimentation basin.

For utilities weighing whether ultrasound belongs in their treatment train, the value here is independence. The findings, the limitations, and the operational takeaways all come from the utility and an academic partner. In other words, they do not come from a vendor brochure.

The operational problem at Shades Mountain Filter Plant

Central Alabama Water’s Shades Mountain Filter Plant uses conventional treatment. The train includes coagulation with ferric sulfate, flocculation, sedimentation, and sand and anthracite filtration. It then adds disinfection with sodium hypochlorite, plus pH and alkalinity adjustment with liquid lime. The sedimentation step relies on a single earthen-bottom basin of just over four acres. Notably, that basin treats up to 80 million gallons per day.

For years, the basin grew seasonal filamentous algae along its perimeter and around the filter intakes. The growth was persistent rather than explosive. Even so, it created a chain of downstream problems. First, algae carried over into the granular filters. As a result, head loss increased, filter run times shortened, and chlorine demand rose. That combination then made it harder for operators to hold a target post-filtration free chlorine residual of 0.5 ppm.

Several factors drove the perimeter growth. The basin configuration, the variable blending of river and lake source waters, and warm summer temperatures all played a part. These are conditions that many surface water plants will recognize.

Why operators wanted an alternative to more chemicals

The conventional fix for basin algae is straightforward. Operators dose an oxidant such as sodium hypochlorite upstream of the sedimentation basin. It suppresses algae effectively. However, it carries a cost. Adding oxidant ahead of settling can turn the basin into a disinfection byproduct (DBP) incubator. Moreover, it can raise the risk of taste-and-odor problems, depending on how much algae dies off and which species are present.

Central Alabama Water’s internal Research and Innovation Department wanted a different path. Specifically, they set out to control the algae without introducing a new chemical that could add to DBP formation. That goal  (operational stability without more chemistry) is what led the team to ultrasonic treatment.

How the ultrasonic system was deployed and monitored

The team installed an MPC-Buoy LG Sonic ultrasonic system in April 2024. They positioned it near the filter intakes at the effluent end of the basin. The unit is solar-powered and designed to treat water bodies up to 500 meters across. It emits low-energy ultrasonic waves at variable frequencies below the surface. These waves disrupt the vertical movement some algae depend on. Because those species need sunlight near the surface and nutrients near the sediment, limiting that movement limits growth, and it does so without dosing chemicals.

The system also carries in-situ probes. It logs pH, temperature, turbidity, dissolved oxygen, and the algal indicators chlorophyll-a and phycocyanin. These readings are recorded every 15 minutes and sent to an online dashboard for real-time review. In addition, the utility added routine monitoring of dissolved organic carbon (DOC) and UV254. The team also used fluorescence spectroscopy at the University of Alabama to characterize the organic matter in the water.

What the study found

The clearest result was visual. For years, a perimeter algae mat had appeared every warm season. However, within one year of installation, that algae growth appeared essentially absent. The authors note that monitoring will continue. This measured framing fits the utility’s broader, evidence-first approach.

Just as important is what the study was careful not to claim. The system did not measurably reduce chlorophyll-a or phycocyanin in the flowing source water. The authors attribute this to limited contact time in a high-flow basin moving up to 80 mgd. Likewise, conventional organic matter metrics (DOC and UV254) did not change significantly. A direct comparison of filter run times was also not possible, because a new high-rate filter building came online during the evaluation. Meanwhile, the fluorescence work showed organic matter behaving in line with expected treatment performance once the system was running.

In other words, the documented win is localized control of attached growth in the basin itself. It is not source-water bloom suppression. The study is precise about that boundary. That precision is exactly what makes it useful.

Where ultrasonic treatment fits in the treatment train

The authors’ conclusion is the line utilities should take away. They describe the ultrasonic system as a complementary operational tool. It reduces reliance on chemical algae control within the basin, rather than replacing existing strategies. For example, enhanced coagulation and powdered activated carbon still have their place for upstream blooms and taste-and-odor events.

For plants dealing with chronic perimeter or basin-attached algae, the framing is clear. Ultrasound offers a low-maintenance, chemical-free option. As a result, it can improve operational stability and reduce downstream filter effects. The authors also note that longer-term datasets will help refine deployment and integration. This is field evidence that accumulates over time, then — not a closed case.

What this means for drinking water utilities

Most plant managers are not trying to restore an entire reservoir. Instead, they are trying to keep attached algae out of their filters and hold a stable chlorine residual. They also want to avoid adding chemistry that complicates DBP and taste-and-odor management. This study speaks directly to that operator-level problem.

It also models the kind of evidence the sector trusts. The study features a named utility, an academic partner, a full monitoring cycle, and honest limitations. Finally, it appears in an industry journal. For utilities evaluating ultrasonic sedimentation basin algae control, the Opflow article is therefore a credible starting point.

The MPC-Buoy combines this ultrasonic treatment with the continuous water quality monitoring described in the study. As a result, operators get both control and real-time visibility from a single solar-powered platform.

Read the study

The full peer-reviewed article is Ultrasonic Treatment Reduces Sedimentation Basin Algae Growth by Melanie Vines, Jeff Cochran, and Leigh G. Terry. You can read it in AWWA Opflow, June 2026 .

Facing chronic algae in your sedimentation basin?

Attached algae can shorten filter runs, drive up chlorine demand, and push you toward more upstream oxidant than you want. If that sounds familiar, ultrasonic treatment may be worth evaluating for your basin. Talk to an LG Sonic expert to assess whether the MPC-Buoy fits your plant’s configuration and source water.