Evaluation of Onsite Sodium Hypochlorite Generation at the Blue Plains Advanced Wastewater Treatment Plant

Due to potential risks associated with transportation and handling of liquid chlorine, the District of Columbia Water and Sewer Authority (DC Water), switched to the use of liquid sodium hypochlorite as the disinfecting agent at the Blue Plains Advanced Wastewater Treatment Plant (AWTP). The escalating cost of bulk purchased sodium hypochlorite prompted DC Water to commission a study to evaluate disinfection alternatives that: 1) are compatible with existing treatment processes; 2) meet all plant effluent disinfection requirements; and 3) reduce life cycle costs of disinfection.The study involved a detailed technical, economic and non-economic evaluation of the feasibility of constructing and operating an onsite sodium hypochlorite generation facility in lieu of bulk purchase. Economic analyses included capital and O&M costs, life cycle costs over a 30-year time horizon, and sensitivity of price of bulk sodium hypochlorite and salt, electric power cost, debt service on life cycle costs.