Investigating the Synergy of an Electrolytic reactor for Bromide Removal with Downstream Treatment Processes

摘要

Meeting the Stage 1/2 Disinfectant/Disinfection By Product Rules is a balancing act for most utilities. The Castaic Lake Water Agency (Agency) treats imported water from the California Aqueduct (West Branch of State Water Project) at its two water treatment plants. Although the water settles in two major reservoirs prior to treatment, high THM concentrations have been experienced in the past upon addition of free chlorine for distribution system residual. To complicate matters, the presence of bromide ion in the range of 100 to 300 μg/L is problematic for two reasons: 1) ozone is applied at both water treatment plants for preoxidation, which reacts with the bromide ion to form bromate by-product, and 2) upon addition of free chlorine, brominated disinfection by-products (e.g. THMs and HAAs) are formed. These brominated by-products have been linked to greater health risks. To address this issue, several prototypes of an electrolytic process were tested at the Agency. Promising results were obtained in terms of bromide, DBP minimization, and microbial inactivation. A Tailored Collaboration project sponsored by AwwaRF was developed with the Agency to further advance the testing. The main purpose of the project was to further characterize and develop technology to fully understand its potential for full-scale drinking water treatment. Optimal ranges of power amperage and of contact time for bromide removal and DBP formation potential reduction were identified. The feasibility and synergy of an electrolytic reactor in a conventional water treatment plant were tested and discussed. Scalability issues were addressed.