New effluent quality regulations or changes to the ultimate discharge point of a wastewater treatment system can require that a system meet new Total Nitrogen (TN) effluent limits. For wastewater treatment systems requiring TN removal, a de-nitrification unit process for nitrate removal follows the SAGR nitrification process.
OPTAER® lagoon based wastewater treatment systems can be adapted to meet a wide range of total nitrogen limits through the use of preanoxic zones within the lagoon system or tertiary denitrifying sand filters. The fully nitrified SAGR effluent is returned to the front of the OPTAER® lagoon system, where incoming wastewater provides a carbon source required for de-nitrification. For small systems or in existing sites where effluent recycle is not practical, SAGR effluent can be passed through a continuous backwash up-flow sand filter with carbon addition for denitrification. The denitrifying sand filter can be combined with a recycled lagoon system effluent to meet lower TN limits.