Together with Hans-Peter Kaiser from the Water Supply Zurich and the other authors of the paper, Elisabeth Salhi and Urs von Gunten developed a real-time control system that adjusts the ozone dose during drinking water treatment. A new sequencing batch reactor measures the ozone decay rate constant at regular intervals. The data are then used to calculate the degradation of micropollutants and the inactivation of microorganisms, and, on the basis of this calculation, the ozone flow is constantly regulated during the treatment process to achieve a pre-defined treatment goal. The new system has been successfully tested for two years in a pilot plant at the Water Supply Zurich and has recently been implemented in the full-scale lake water treatment plant Lengg.

This study is the result of a longstanding collaboration between Eawag and the Water Supply Zurich and makes a valuable contribution to real-time process control in ozonation systems, thereby helping to improve the cost-effectiveness of ozonation in drinking water treatment.