The city sought a cost effective technology that could provide more stable disinfection performance over a broad range of pH conditions.
Performance of existing chlorination process becomes less effective during some periods of summer and fall months. The city of St. Helena sought a cost effective technology that could provide more stable disinfection performance over a broad range of pH conditions and could easily retrofit the existing system.
VigorOx® WWT II is desirable because of its stable and high disinfection efficiency over a broad range of pH and of its capability of retrofitting into existing treatment train, in addition to its other unique features (e.g., ease of operation and very low toxicity to aquatic organisms). The Water Treatment team provided complete services and process evaluation, including on site bench scale tests and full-scale trial.
The three-month full-scale test confirmed the effectiveness of VigorOx WWT II and narrowed down the operating conditions needed to achieve the disinfection goal.
Specifically, with Ct values (C being the dose in mg/L and t being contact time in minutes) of 400 mg-min/L of higher, VigorOx WWT II is able to comply with the permit limit.