A COMPREHENSIVE ASSESSMENT OF THE PERFORMANCE OF PERACETIC ACID DISINFECTION FOR WASTEWATER RECLAMATION

Abstract

Peracetic acid (PAA) is an alternative to chlorine-based disinfectants that is emerging recently.
This paper is the review of a previous research work that has been carried out over several years and that was aimed at a comprehensive performance assessment on PAA as a disinfectant for secondary effluent.
The process was studied at bench and pilot scale using the effluent of a wastewater treatment plant. In detail, in the view of complying with standards on discharge in surface water and agricultural reuse, two target microorganisms, namely Escherichia coli and faecal coliform bacteria, were selected for: (1) determining PAA decay and decay kinetics as a function of operating conditions; (2) evaluating PAA suitability as a disinfectant; (3) assessing long-term disinfection efficiency; (4) investigating disinfected effluent biological toxicity on some aquatic indicator organisms (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum); (5) comparing PAA with conventional disinfectants (sodium hypochlorite, UV irradiation). Experimental results pointed out that PAA disinfection was capable of complying with Italian regulation on reuse (10 CFU/100 mL for E. coli) and that it was competitive with benchmarks. Moreover, no regrowth phenomena were observed, as long as needed for agricultural reuse of the effluent (29 h after disinfection), even at negligible concentrations of residual disinfectant.

Finally, the toxic effect of PAA on the aquatic environment was due to the residual disinfectant in the water, rather than to chemical modification of the effluent and to the generation of by-products.