NITRATE REMOVAL FROM WATER-SUPPLIES USING BIODENITRIFICATION AND GAC-SAND FILTER SYSTEMS

In this paper, a study on using fixed-film biological denitrification to remove nitrates from water supplies is reported. Fixed-film biologi cal systems have not been used in water supply systems in the U.S. alt hough they are proven to be efficient and economical for removing nitr ates with the reason being the possibility of imparting residual organ ics, suspended solids and bacteria to the treated water. In this resea rch, fixed-film upflow biodenitrification columns were operated under carbon-starved conditions and the effluent was treated with a granular activated carbon (GAC) and sand filter system (combined in one unit) to remove residual organics and suspended matter. The system resulted in an average effluent turbidity of 0.8 NTU, and COD and total suspend ed solids (TSS) concentrations of 5.7 and 0.6 mg/L, respectively.