Peracetic Acid (PAA) versus Chlorination/De-chlorination – A Disinfection Comparison

摘要

Peracetic acid (PAA) is an approved disinfectant that has been used for decades in the food andmedical industries, however it has historically been considered too expensive for use inwastewater disinfection applications. Recently, rising concerns around trihalomethanes (THMs)have opened the door to exploring alternative non-chlorine based disinfection technologies. TheCity of St. Augustine with the permission of Florida Department of Environmental Regulationperformed a pilot test to compare the disinfection performance and costs of a PAA disinfectionsystem versus a chlorination/de-chlorination system. The 5.0 Million Gallons per Day (MGD)St. Augustine, Florida Wastewater Treatment Plant (WWTP) was selected for the trial due to thefact that the plant’s flow was split between two identical contact chambers. This configurationenabled a direct head-to-head evaluation between the PAA and chlorination/de-chlorinationsystems across three performance criteria that were critical to the plant; disinfectionperformance, effluent toxicity and chemical costs. The objective was to conduct a full-scaledemonstration test to determine if a PAA disinfection system, using automated dose controltechnology could effectively reduce pathogen levels to achieve regulatory compliance while atthe same time preventing harmful residuals from forming in the treated effluent. The test resultsdemonstrated that PAA was consistently able to reduce pathogen loads to achieve regulatorycompliance, prevent harmful residuals from forming in the treated effluent, and reduce its overallchemical consumption and cost.