Wastewater Treatment Systems – Nitrogen Reduction
treatment capacities of 1514 L/d (400 gal/d) to 5678 L/d (1500 gal/d) that are designed to provide reduction of
nitrogen in residential wastewater. Management methods for the treated effluent discharged from these
systems are not addressed by this Standard. A system, in the same configuration, must either be
demonstrated to have met the Class I requirements of NSF/ANSI 40 or must meet the Class I requirements of
NSF/ANSI 40 during concurrent testing for nutrient removal.
The water chemistry of a site for installation and use of these systems is critical to achieve expected water
quality results. Before these systems are installed at a location, the water used within the residence must be
analyzed to verify that there is sufficient alkalinity to achieve the system’s performance. Refer to Annex A for
Natural systems involving features such as vegetation, wetlands, free access or buried sand filters, and soil
systems may be evaluated using this protocol as long as effluent samples are representative of all treated
effluent discharged from the system, as sampled from a central point of collection of all treated effluent.