Exploring the Potential of Peracetic Acid for Wastewater Disinfection: Insights from a Pilot-Scale Study

Wastewater disinfection is a key treatment for the protection of the environment and public health from pathogenic infections. Peracetic acid (PAA) is an organic peroxyacid with a high oxidation potential that can be an alternative to conventional disinfectants. The aim of this pilot-scale study was to assess six disinfection conditions using PAA as a disinfectant agent of wastewater. To this end, a 6-month study was performed, and six disinfection conditions were studied: 15 mg/L of PAA with 5, 10, and 15 min of contact time; 10 mg/L of PAA with 10 and 15 min of contact time; and 5 mg/L of PAA with 10 min of contact time. After the disinfection, an increase in the 5-day biochemical oxygen demand (BOD5) and the chemical oxygen demand (COD) was observed; however, this was not proportional to the PAA dose because the higher doses tested did not result in a higher increment. In addition, PAA resulted in a slight decrease in pH. Nevertheless, the PAA impact on pH was not dependent on the PAA dose or the contact time. The PAA disinfection performance showed that doses of 10 and 15 mg/L achieved Escherichia coli log reduction higher than 2 logs, and even higher than 3 logs when 15 mg/L were tested with 10 and 15 min of contact time. The results showed also that the contact time was not a limiting factor for the PAA performance, at least for the contact times used in this study. This pilot-scale study proved that PAA can be an alternative disinfectant for wastewater.