How do I meet my Total Nitrogen limits?

Total Nitrogen Limits are now routinely included in the discharge requirements for projects throughout the United States. Each state and local jurisdiction has varying requirements, but the default Total Nitrogen (TN) limit in many areas is the US EPA drinking water standard of 10 mg/liter.

Depending upon the treatment technology selected, the standard may or may not routinely be met. The more sophisticated and expensive treatment technologies such as the Membrane Bio-Reactor (MBR) can routinely meet the 10 mg/l limit. With the more passive and less expensive onsite treatment systems, an external carbon source is required to complete the denitrification process. The carbon source is typically added at the end of the treatment process and can take various forms – liquid methanol, wood media, and other proprietary forms.

It has been our experience that carbon injection into a tank will not be successful as the nitrifying bacteria (bugs) need a media to grow on. IWS utilizes a patented process provided by ENR Technologies, LLC ( which combines wood media in a single pass upflow filter for denitrification. The wood media provides a long term carbon source that will last 10 years and requires very little maintenance in the single pass upflow configuration. There is no chemical addition or injector calibration required. The real selling point for IWS is that it works! Our data shows that in most cases Nitrite/Nitrate is completely nitrified, which allows the TN to be well below the 10 mg/l limit.