water as function of the ozone dose (in mg/min) is pre- sented in Figure 4. The higher the ozone dose, the higher the bacterial removal and COD oxidation. Best results were obtained with ozone doses about 20 mg/min where 72% and 78% of FC and TC, respectively were inacti- vated. No effect of pH was determined for fecal and total coliforms inactivation at the different pH values tested (pH = 5, 7 and 9, data not shown). This behavior, how- ever, is reasonable if considering that molecular ozone is actually the chemical species carrying out bacteria disin- fection instead of hydroxyl radicals, which will be af-fected by pH