Environ. Sci. Technol. 2009, 43, 6579–6584
Assessment of Peracetic Acid Disinfected Effluents by Microbiotests M . A N T O N E L L I , * ,† V . M E Z Z A N O T T E , ‡ AND M. PANOUILLÈRES§ Politecnico di Milano, DIIAR - Environmental Section, Piazza Leonardo da Vinci 32, 20133 Milano (I), Universita´ degli Studi di Milano Bicocca, DISAT, Piazza della Scienza 1, 20126 Milano (I), and Ecole Normale Supe´rieure de Lyon, 46, Alle´e d’Italie, 69364 Lyon Cedex 07 (F)
Received March 26, 2009. Revised manuscript received July 2, 2009. Accepted July 6, 2009.
Bioassays were performed by commercially available kits on peracetic acid (PAA) solutions, at different concentrations, and on secondary effluents (from two different wastewater treatment plants) after disinfection at bench-scale, considering both samples containing residual active PAA and the same samples where residual PAA was quenched. Four indicator organisms were used: Vibrio fischeri, Thamnocephalus platyurus, Daphnia magna, and Selenastrum capricornutum. The experiments lead to conclude that Thamnocephalus platyurus is a very sensitive organism, probably not adequate to perform a reliable toxicity assessment of effluents for monitoring purposes. The presence of specific organic compounds deriving from human metabolism and urban pollution, even at very low concentrations, can affect the results of bioassays, especially those performed on Vibrio fischeri. PAA is toxic for bacteria and crustaceans even at concentrations lower than the ones commonly used in wastewater disinfection (2-5 mg/ L), while its effect on algae is smaller. The toxic effect on bacteria was expected, as PAA is used for disinfection, but its possible influence on biological processes in the receiving aquaticenvironmentshouldbeconsidered.Toxicityoncrustaceans would confirm the fact that discharging disinfected effluents could raise some environmental problems.
Introduction In Italy, the use of chlorine-based disinfectants is strongly discouraged due to the risk of toxic DBPs (disinfection byproducts) formation, peracetic acid (PAA) represents a suitable alternative to sodium hypochlorite because of its broad spectrum efficiency and the comparable way of application, which permits an easy and relatively cheap upgrade of existing plants. However, the knowledge about PAA action is limited, especially with respect to DBPs formation and direct and indirect toxicity. As for DBPs formation, no toxic DBPs seem to be generated when low doses are used (
