Inactivation of E. coli and P. aeruginosa by UV-A-Activated PMS and PDS, and Alkaline-Activated PDS: A Comparative Study

Abstract

The aim of the present study was to evaluate the efficacy of peroxydisulfate(PDS)/peroxymonosulfate(PMS) activated using different methods for inactivating E.coli and P.aeruginosa . The UV-A, UV-A/PDS, PMS, and NaOH/PDS processes were used to inactivate E.coli and P.aeruginosa . Three different sulfate salts (K 2 S 2 O 8 , Na 2 S 2 O 8 and Oxone) were activated with UV-A radiation, and their inactivation effects were determined. During 30 min of UV A (Ultraviolet-A) radiation, the addition of 3 mM K 2 S 2 O 8 , Na 2 S 2 O 8 , and Oxone increased the removal efficiency of E. coli by 1.76, 1.51, and 2.47 log, respectively. For P. aeruginosa , there were increases of 1.44, 1.62, and 2.55 logs, respectively. The highest removal efficiency was obtained with oxone + UV-A for E.coli and P.aeruginosa . To examine the inactivation effect of alkaline (NaOH)-activated peroxydisulfate on microorganisms, studies were carried out using two different doses of K 2 S 2 O 8 (2 and 3 mM). With an increase in the PDS concentration, the removal efficiency of both bacteria increased. Higher removal efficiencies were obtained at higher base/PDS ratios. When the PDS concentration was increased from 2 to 3 mM at the same NaOH/PDS (0.25) ratio, the time required for 4 log bacteria removal was reduced by 33% for E.coli , while there was a decrease of more than 44.2% for P.aeruginosa .