Ultrasonic Algae Control for Power Plant Cooling

Thermal power generation facilities depend on massive cooling volumes to condense steam and reject waste heat. At the R.M. Schahfer Generating Station in Northwest Indiana, operated by the Northern Indiana Public Service Company (NIPSCO), cooling water drawn from the Kankakee River circulates through on-site cooling reservoirs before discharge. Shallow, sunlit, and nutrient-rich reservoir environments create prime conditions for algal proliferation. Photosynthetic activity from uncontrolled algal blooms elevated total suspended solids (TSS) and raised water pH. Under National Pollutant Discharge Elimination System (NPDES) permits and federal steam electric power effluent guidelines, exceeding strict thresholds for TSS and pH carries financial penalties and forces plant operators to curtail discharge volumes, risking power generation outages.

To suppress biological growth, industrial operators historically relied on chemical dosing, including copper-based algaecides, sulfuric acid for pH control, and ultraviolet blockers. Chemical treatments rupture algal cells, releasing cellular contents and toxins directly into the water column. Furthermore, residual chemicals risk exceeding downstream ecotoxicity limits, while repeated chemical applications add procurement costs and operational complexity without delivering permanent bloom suppression.

Operational Objectives and Technical Selection
NIPSCO aimed to achieve consistent discharge compliance by keeping TSS concentrations strictly below regulatory thresholds, stabilizing effluent pH, and decreasing chemical reliance across cooling operations. The utility selected LG Sonic to deploy floating MPC-Buoy systems directly into the station's cooling water reservoir.

The selected technology utilizes continuous low-power ultrasound emitted across specific sound frequencies. The acoustic waves create an effective sound layer in the upper water column that inhibits the vertical buoyancy regulation of algal cells. Without the ability to migrate toward sunlight for photosynthesis, algal populations sink to deeper, darker water layers and die off gradually without cell wall lysis or intracellular toxin release. Each autonomous buoy integrates solar panels, battery storage, and multi-parameter sensors that record water quality indicators, transmitting telemetry via cellular communication to optimize ultrasonic dosing frequencies based on real-time biological conditions.

Deployment Process and Environmental Performance
The implementation involved installing five solar-powered floating platforms across the reservoir to establish acoustic coverage across the water body. Real-time water data allowed remote technical teams to calibrate acoustic programs against incoming nutrient fluctuations from river makeup water.

Following deployment, reservoir TSS concentrations dropped below 3 mg/L, remaining consistently beneath regulatory monthly limits. The stable biological control eliminated the need for sulfuric acid dosing to regulate pH, saving an estimated $300,000 in operational costs within the first year. NIPSCO completely phased out ultraviolet blocker additions at cooling tower circuits and decreased overall algaecide consumption by 66 percent over two years. By mitigating algal proliferation at the raw-water reservoir stage, the plant protected downstream condensers and cooling towers against biofouling while meeting environmental discharge parameters.

Edited by Evgeny Churilov, Induportals Media - Adapted by AI.

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