Performic Acid Testing for Evaluation of Disinfection Efficacy and Toxicity in WWTP Secondary Effluent at Both Laboratory and Onsite Pilot Demonstration

PFA has been used in Europe for nearly 20 years as a disinfectant for wastewater because of its environmentally sustainable characteristics. The goals for this study were to determine the required conditions for PFA efficacy to achieve permitted limits for bacteria and toxicity at the Gresham WWTP; to evaluate the log inactivation of PFA for indicator organisms; and to compare the efficacy of PFA to chlorine. Comparing PFA to hypochlorite, lab testing demonstrated that PFA required 5.6 times less dose to reduce E. coli to below the WWTP permit limit using a 15-minute contact-time. The pilot results showed a CT (dose * contact-time) of 20 - 40 mg * minute/L to provide effective disinfection (with a 2-3 log reduction). PFA doses up to 4 mg/L with a contact-time of 15 minutes showed no toxic effects. This evaluation proved PFA to be a good disinfectant alternative for the North American market.