New York City Evaluation of Alternative Disinfection Technologies for Bnr Wastewater Treatment Plants

New York City Department of Environmental Protection designed, constructed and operated two pilot disinfection facilities: A chlorination/dechlorination pilot, consisting of a 2,000 gal contact tank and instrumentation, treating flows up to 100 gpm; and an ultraviolet light (UV) pilot consisting of two low pressure, high output units, treating flows of approximately 5 mgd. The objective of the study was to provide information necessary to guide the selection process and full-scale design of disinfection systems at wastewater treatment plants where Biological Nutrient Removal is being implemented. This was achieved by comparing performance and operations and maintenance requirements of the systems. Both pilots demonstrated disinfection effectiveness. Effectiveness of UV disinfection was not impacted by low ammonia concentrations, while the chlorination/dechlorination pilot experienced significant increase in chemical demand during periods of low influent ammonia concentrations. UV disinfection was not observed to generate disinfection by products while the chlorination/dechlorination pilot generated small concentrations.