Wastewater Disinfection with Peracetic Acid

Peracetic acid (PAA) was evaluated on the secondary effluent as a potential disinfectant in a lab study and in a pilot project. In the lab study, PAA was compared with sodium hypochlorite at concentrations between 3 and 7 mg/L against fecal coliform and E. coli for 9, 17, and 30 min contact times. In the pilot project, three lower doses of PAA (1.3, 1.5, and 2.0 mg/L) were tested. The antimicrobial effect of PAA against fecal coliform and E. coli was found to be directly proportional to its dose and length of contact time. Similar increases were observed in the microbial inactivation when the contact time was increased from 9 min to 30 min. The data collected during the pilot project suggests that PAA can be a viable alternative to sodium hypochlorite, however, further studies are needed to investigate the PAA decay rate and its impact on the environment.