AWWA JAW41500

Ion exchange with chloride-form anion resin is recommended as a best available technology for removing nitrate from drinking water. Disposal of spent regenerant brine remains a difficult problem, however. A pilot study focused on a new ion exchange process with batch biological denitrification and reuse of the spent brine. Spent regenerant brine from regeneration of the nitrate-loaded ion exchange column was denitrified in a sequencing batch reactor using methanol as a carbon source. After denitrification, the spent brine was filtered, compensated with NaCl, and reused. Brine denitrification and reuse proved feasible only when using the nitrate-selective trethyl- and tributyl-amine resins. Compared with the conventional ion exchange process, brine reuse reduced the salt consumption and waste discharge by more than 90 percent. Includes 15 references, tables, figures.