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The World Health Organization (WHO) recommends a maximum limit for nitrate of 50 ppm as NO3 while the USA and some other countries have set a maximum MCL of 10 ppm as N (or 45 ppm as NO3).
Nitrate removal using brine regenerable strong base anion resins is an established process. Nitrate selective resins, such as our Purolite A520E, were developed for use specifically in waters with high sulfate to nitrate ratios. For waters with low sulfate levels, our Purolite A300E Type II SBA resin may offer better economics. Our high-capacity Type I SBA A600E/9149 can also be used. Purolite A520E is favored, however, because nitrate fixed onto the bed is not displaced from Purolite A520E by sulfate as is the case for traditional Type I and II resins. Larger plants that are well controlled should evaluate both nitrate selective and standard Type I and II resins since the specific water chemistry will dictate which will yield the lowest operating cost.
Our technical experts can help by analyzing costs through our PureDesign™ economic comparison software.
For municipal or community water systems where on-site brine disposal is not permitted, hauling and off-site disposal of waste brine can be cost prohibitive. To address this, Purolite and Applied Research Associates have jointly developed the patented WIN process for nitrate removal, using proprietary weak base anion resin technology. The WIN process, while requiring more operator attention, can significantly reduce waste volume compared to brine regenerable resins while producing more benign nitrate waste.
Advantages of Purolite ion exchange resins for nitrate removal include:
• Single supplier for the full range of resin options available to the industry.
• Reliable easy-to-use PureDesign™ software for ease of design.
• Customizable brine minimization approaches.
• Multi-contaminant design approach is possible for simultaneous removal with other contaminants.