Peracetic Acid to Replace Gaseous Chlorine for Wastewater Disinfection: From Bench Scale Testing to Pilot Demonstration

The objective of this study was to assess the feasibility to use peracetic acid (PAA) disinfection technology at the 20-mgd Northside Wastewater Treatment Plant (NSWWTP) in Danville, Virginia. This technology was being evaluated to replace the plant’s existing gaseous chlorination system to eliminate the associated safety concerns. The focus of this presentation is to demonstrate the use of a disinfection pilot reactor (DPR) to (1) evaluate the effectiveness of PAA as the primary disinfectant to achieve compliance with the plant’s National Pollutant Discharge Elimination System (NPDES) permit microbial criteria under varying plant operating conditions, (2) determine the dose rate and contact time required to achieve the disinfection goal, and (3) measure the potential impact of PAA on the wastewater effluent quality.The pilot results successfully demonstrated PAA technology to be an effective disinfection process for this plant. A PAA dose rate of 1.3 mg/L and a contact time of 33 minutes were sufficient to consistently achieve the bacterial reduction goal. In addition, monitored results of various water quality parameters confirmed that adding PAA to the wastewater did not cause any adverse impact to the effluent wastewater quality, including chronic toxicity, pH, TSS and BOD5.