Interpretation of water disinfection employing a commercial mixture of peracetic acid

FLORES, M.; BRANDI, R.J.; CASSANO, A.E.; LABAS, M.D.

CHEMICAL ENGINEERING JOURNAL

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2012

1385-8947

The Chemical disinfection of Escherichia coli employing a commercial mixture of peracetic acid (PAA) was studied. It was found that very low concentrations of disinfectant are required to reach a very important inactivation in a very short time. Special experiments employing PAA free hydrogen peroxide demonstrated that this result is mainly attributable to the presence of the acid in the mixture, but the occurrence of hydrogen peroxide under practical operating conditions produces an important synergetic effect that significantly increases the disinfection performance. A possible explanation has been proposed. AIt seems probable that a transition metal ion catalyzed homolysis of PAA acid initiates a chain reaction that originates several radical oxidative species. In particular, the hydroxyl radical and, to a lesser extent, other similarly very active species could be responsible for the extremely fast and irreversible destruction of vital bacteria components. After this fast initial attack, some components of the bacteria that inhibit the action of hydrogen peroxide may have been removed. Thereafter, the obstacles to the emergence of the synergic action of the second oxidant have been eliminated and it can be immediately unveiled. These results contrast entirely with those that we observed using hydrogen peroxide alone. Our results show that 8 mg L-1 27 of peracetic acid from a commercial mixture of PAA are enough to produce more than 4 logs decrease in bacteria concentration in less than 70 s.