Tertiary treatment is an optional process and the most advanced form of treatment.  This level of treatment removes excess nutrients from wastewater, such as nitrogen and phosphorus, but can also include processes to eliminate other pollutants of concern.  This advanced treatment involves several sophisticated processes that utilize many types of treatment, including chemical and biological processes. 

Unfortunately, tertiary treatment is not used or currently required by law in New Jersey.  However, tertiary treatment is used in areas where techniques are used to reuse wastewater after treatment for various purposes (see Sludge Management).