Proof of the Pudding: Equipment Selection Criteria and Three Years of Experience with an Ultraviolet Disinfection System at a Municipal Wastewater Treatment Plant

As part of an expansion to an average flow of 45.9 million gallons per day, the Ypsilanti (Michigan) Community Utilities Authority elected to install ultraviolet disinfection to replace their existing chlorination/dechlorination process. This paper reports the unique, collaborative methodology used to select the system based on not only the life cycle costs, but active participation of the stakeholders. A team including representatives of all departments at the Authority WWTP critically evaluated manufacturer provided information, then visited selected sites with similar types of equipment as part of making the final selection. A low-pressure, high intensity system was selected, based on life-cycle cost, reliability, safety, and ease of operation. The selected equipment was pilot tested for validation of the dose-kill relationship. This paper describes the unique methodologies used in making that decision. The full-scale system has been successfully operating since spring 2003. Actual operating results are compared to evaluation criteria provided by the manufacturer prior to selection.