Case Study: Hydro International achieves up to 50% project cost savings and major footprint reduction for CSO disinfection with ANSYS Fluent modeling

Using Computational Flow Modeling for Improving Combined Sewer Overfl ow System Design

Hydro International, maker of the Storm King advanced hydrodynamic vortex separator (HDVS), needed to validate and explain why its CSO (combined sewer overflow) system achieved effective disinfection at about three minutes — far below the conventional 15‑minute contact time regulators expected. To address this regulatory and technical challenge, Hydro worked with ANSYS (using ANSYS Fluent) to investigate the hydrodynamics and contact times in the Storm King system.

Using ANSYS Fluent, Cardiff University and Hydro International built and ran computational flow models of the Storm King across full‑scale flow ranges, comparing modeled residence times and kill rates with laboratory experiments. ANSYS’s modeling showed that residence times and disinfection efficacy matched or exceeded conventional tanks, provided insight into the disinfection mechanism, supported proposals to relax the 15‑minute mandate, and enabled municipalities to cut CSO project costs by up to 50% while reducing footprint to about one‑tenth, allowing Hydro International to offer a lower‑cost, high‑performance solution.

Hydro International