A major duck slaughterhouse in France faced significant challenges maintaining their cooling tower water within acceptable levels for bacteria and Legionella. Chemical treatment regimens in use were inconsistent and were unable to keep the towers algae free. The 7 evaporative towers were in the range of 500 to 1500 L in water volume size. The Simpson supplied AOP system was installed in the sump so as not to interfere with the tower recirculation systems. Sump water was extracted, treated with ozone and returned to the sump. Tower efficiency improved so much that the operation was reduced from 24 hrs per day to 16 hours per day savings some 33% in overall energy costs while reducing bacteria counts well below 250 CFU/ml and eliminating all algae.