Utilisation de l’acide performique pour réduire la pollution microbiologique et chimique des eaux résiduaires urbaines

Performic acid (PFA) is used to disinfect urban wastewater (WW) due to its proven effectiveness against various pathogenic microorganisms. However, its advantages over ozone, one of the main disinfectants in WW treatment, as well as its reactivity with pharmaceutical molecules, remain poorly documented. This study, conducted on a pilot plant continuously fed with nitrified water, compares the efficiency of PFA, either alone or in combination to generate advanced oxidation processes (AOPs), to that of ozone in eliminating three pathogenic microorganisms (Escherichia coli (E. coli), intestinal enterococci (IE), and spores of sulfite-reducing bacteria, SSRB) and seven pharmaceutical molecules commonly detected in the Parisian WW. The results show that PFA effectively removes E. coli and IE (with increasing removal between 0.8 and 2 mg PFA/L) and is more efficient than ozone at all tested specific doses (0.14 to 1.00 gO₃/gDOC). The SSRBs were better removed with UV-C/PFA and ozone/PFA AOPs, due to reactive species generated by the decomposition of PFA through ozone and/or UV-C photolysis. In addition, the removal of pharmaceutical molecules by PFA showed low average removals (from 6 to 45% for 2 to 10 mg PFA/L). Moreover, UV-C/PFA improved the average removal rates, particularly at low doses (22% at 2 mg PFA/L), although this improvement was not due to a synergistic effect. In contrast, compared to PFA, ozone at high specific doses led to higher removal rates (from 62 to 92% for 0.48 to 1.00 gO₃/gDOC). Furthermore, at a low specific ozone dose (0.29 gO₃/gDOC), ozone/PFA proved more effective than the individual use of PFA or ozone.