Case Study: Ritsumeikan University restores lake water quality and reduces toxic substances with COMSOL Multiphysics

Ritsumeikan University - Customer Case Study

Ritsumeikan University confronted oxygen-depleted reservoir water at the Sounoseki Dam, where low dissolved oxygen allowed toxic metals and organic pollutants to persist. To design a cost-effective way to restore the lake’s self‑purifying capacity, the university used Comsol’s COMSOL Multiphysics software (with CFD and Chemical Reaction Engineering modules) to study the coupled effects of wind, waves, currents, sediment resuspension, diffusion, and chemical reactions.

Comsol’s multiphysics simulations identified optimal injection locations, depths and flow rates and revealed a large-scale recirculation region that could be used to spread microbubbles efficiently. Using those results, field trials injected oxygen microbubbles (2–5 L/min) into a ~1 million m3 reservoir for about one month, producing a sharp reduction in NH4‑N, PO4‑P, dissolved Fe and Mn concentrations and demonstrating effective, scalable oxygenation guided by Comsol.

Ritsumeikan University

Shuya Yoshioka

Associate Professor