Nitrate is a widespread contaminant found in groundwater and surface water throughout the United States. Nitrate, released from fertilizer runoff, can lead to methemoglobinemia. Due to its health concern, the maximum contaminant level (MCL) of nitrate in drinking water is set to be 10 mg-N/L in the United States. Because of its properties (e.g., highly soluble, mobile, chemically inert in most natural systems), nitrate is not readily removed by conventional water treatment technologies.  In the United States, ion exchange (IX) is the most commonly used technology for treatment of nitrate in drinking water. However, the major concern for IX treatment is the need for frequent resin regeneration with concentrated salt brines. The regeneration process produces a waste stream with high concentrations nitrate and other contaminants in addition to the high background salt levels. Chemical or biological treatment of waste brines has been researched to enable recycling and repeated reuse prior to disposal. While these technologies show promise in improving environmental footprint of IX systems, there has not been a systematic study to quantify environmental impacts or economic costs of IX systems incorporating brine regeneration technologies. In this contribution, the overall environmental impacts and economic cost of conventional IX treatment processes and hybrid IX/catalytic treatment processes for nitrate are evaluated and compared using life cycle assessment (LCA). The hybrid system incorporates a novel catalyst treatment process (Pd-In/C) we have been operating continuously in our laboratory to treat synthetic and waste IX brines. Analysis examines the sensitivities to different operating parameters of the hybrid system (e.g., brine recycle ratio, catalyst longevity, fouling, regeneration). Results for the hybrid IX/catalyst system will also be compared to hybrid IX systems incorporating chemical reduction (zerovalent iron) and heterotrophic biological reduction processes for nitrate.

Environmental and economic sustainability assessment of a hybrid ion exchange/catalytic treatment system for nitrate removal from drinking water

246th National Meeting (2013)

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