An overview of the effectiveness of peracetic acid as a disinfection alternative to chlorination when treating wastewater
Peracetic acid is a wastewater disinfection alternative that is gaining attention due to its ability to provide bacterial inactivation performance competitive with other mature technologies. It is delivered as a solution in which it is in equilibrium with hydrogen peroxide, acetic acid and water. Its efficacy can be tested in an onsite laboratory using a jar tester and a fresh, undisinfected effluent sample. There is a full-scale application in St. Augustine, FL, and another municipal facility in Frankfort, KY, that uses PAA as a full-scale backup to its ozone disinfection system.
Compared with other chemical oxidants used in water and wastewater treatment, PAA has a relatively high oxidation potential that makes it attractive for disinfection. It is effective against a range of microorganisms and is most effective at pH values below the logarithmic value of its acid dissociation constant [pKa (8.2)], but has high efficacy up to a pH of about 9. It is also effective at low temperatures and is relatively unaffected by effluent organic matter compared with other chemical oxidants used for disinfection (e.g., chlorine or ozone). Peracetic acid can provide cost savings, which, coupled with its ability to provide treatment of challenging effluent while meeting stringent DBP limits is driving its evaluation.