Frontier completed a pilot study at a western municipality for nitrate removal from the city’s drinking water supplies. The city owns and operates a reverse osmosis (RO) plant for treatment of hardness and nitrate in the city water supplies. Changes to their discharge permit will necessitate nitrate treatment and reuse the brine stream produced from the RO. Using an expanded bed, upflow bioreactor, FWS successfully demonstrated full and efficient denitrification from concentrations that reached 72 mg/L nitrate as N in the RO brine stream and post treatment to meet EPA standards for drinking water. Results from the successful pilot study lead to preliminary design of a full scale 1.67 MGD RO brine treatment plant for the city.
To protect local ecosystems from selenium contamination, a water district in California operates a demonstration-scale plant for treatment of selenium in high-salinity natural waters. To test an upgrade to plant capacity and operation, Frontier Water Systems was selected to pilot the SeHAWK® process in conjunction with ultrafiltration and reverse-osmosis pre-treatment.
Over four months of operation, the SeHAWK® process demonstrated selenium removal rates >95%. Despite changes in water quality, including spikes in feed nitrate concentration and TDS, the SeHAWK® pilot process achieved results that exceeded pilot goals. These results were achieved while operating at a contact time equal to 20% of other conventional biological treatment also tested on site.