Using selectivity to evaluate aqueous- and resin-phase denitrification during biological ion exchange.

An increased fertilizer application for agricultural purposes has resulted in increased nitrate (NO) levels in surface water and groundwater around the globe, highlighting demand for a low-maintenance NO treatment technology that can be applied to nonpoint sources. Ion exchange (IEX) is an effective NO treatment technology and research has shown that bioregeneration of NO laden resins has the potential to minimize operational requirements and brine waste production that often prevents IEX application for decentralized treatment. In this work, batch denitrification experiments were conducted using solutions with low IEX selectivity capable of supporting the growth of denitrifying bacteria, while minimizing NO desorption from resins, encouraging resin-phase denitrification.