Aberdeen, WA Water Resource Recovery Facility Disinfection System Evaluation

This paper describes an alternatives evaluation for upgrading the system used for disinfection of effluent discharged by the City of Aberdeen’s Wastewater Treatment Plant (WWTP). The City currently uses gas chlorination for disinfection of WWTP effluent and a gas sulfur dioxide system for dechlorination. Although the disinfection system has proven to be safe and effective in meeting the City’s NPDES permit limits, the City is evaluating options for upgrading or replacing the existing disinfection system because of:the age of equipment, approaching the end of its useful life,safety and health considerations for plant staff and the public associated with transport, storing and handling of chlorine and sulfur dioxide gases, both of which are extremely toxicmore stringent regulations and corresponding costs of compliance, and decreasing reliability of gas shipments.Nine alternatives were identified and screened, and a preferred alternative identified.