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.
Denitrification in Municipal Drinking Water
SeHAWK® 240 gpm Municipal Brine Turnkey Plant Installation
A western US municipality operates a reverse-osmosis drinking water plant that produces a brine stream with elevated selenium and nitrate. In order to comply with state regulations, the brine stream must be treated prior to being discharged to a local waterway. After completing a 2-month pilot study, Frontier Water Systems was selected to design and supply a treatment plant, centered around a SeHAWK® Link modular bioreactor. The SeHAWK® Link provides the customer with the flexibility for future expansion, a compact footprint, and easily integrates with the existing RO and various auxiliary equipment and treatment processes.
Since startup, the SeHAWK® has consistently removed nitrate to below detection limits and has removed selenium to below the stringent discharge limit of 4.6 ug/L. The success of the plant has enabled the municipality to attain greater independence of drinking water supplies, securing safe drinking water for current needs and future town growth.
SeHAWK® Pilot Demonstration for High Salinity Waters
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.