State-of-the-Art Nitrogen Upgrade Program

Over the past ten years, AlexRenew has made significant enhancements to its treatment process to meet new, stricter nitrogen removal standards. Through the State-of-the-Art Nitrogen Upgrade Program (SANUP), AlexRenew has been helping to improve the overall quality of Potomac River and the Chesapeake Bay watershed. 

SANUP was a comprehensive, multi-year program that included several projects.

Package A – Supplemental Carbon Facility Improvements

AlexRenew relies on microbes to help us clean dirty water. The microbes need energy to grow and work, which they get from supplemental carbon. This project increased AlexRenew’s capacity to supply supplemental carbon to our treatment process.  Supplemental carbon helps us remove phosphorous and improve the settling of solids. 




Package B – Centrate Pretreatment Facility  

In March of 2015, AlexRenew opened its Centrate Pretreatment Facility (CPT). This facility is the first designed and separately constructed full-scale sidestream deammonification system in North America. Inside of the CPT, Anammox® bacteria, also known as red bugs, work in tandem with other types of microorganisms to transform the ammonia-nitrogen in dirty water into harmless nitrogen gas. This gas can be safely released back into the atmosphere. This revolutionary deammonification process uses less air, energy, and chemicals than traditional treatment processes and offers opportunities for operation and maintenance cost savings. 


Package C – Nutrient Management Facility

Inside the Nutrient Management Facility
Inside the Nutrient Management Facility

Another SANUP project is the Nutrient Management Facility. This 18-million-gallon facility helps balance the amount of ammonia-nitrogen that goes into AlexRenew’s biological reactor basins.

On top of the facility is Limerick Street Field. This multi-purpose athletic field is a community amenity that provides a green gathering place for residents. AlexRenew formally presented the field to the City of Alexandria on October 23, 2015. The City of Alexandria will maintain the field. 




Package D – Biological Reactor Basin 6

As part of SANUP, AlexRenew also added another biological reactor basin — BRB 6. In the biological reactor basins, we put microbes to work cleaning dirty water. In order to remove more nitrogen, AlexRenew needed to employ even more microbes, including the red bugs at work in the Centrate Pretreatment Facility. BRB 6 makes space for more microbes with 3.8 million gallons of additional secondary treatment capacity.

The red bugs used in the CPT are helping to seed AlexRenew’s mainstream deammonification process, which will occur in the biological reactor basins.