A public-private partnership made possible the first operating implementation ofthe innovative DEMON® sidestream deammonification process in North America. Infact, this is the first operating full-scale installation of any form of anammox sidestreamtreatment in North America. HRSD, a regional wastewater treatment utility that serves17 localities in southeastern Virginia, and World Water Works, Inc. (WWW), whichspecializes in developing and providing highly efficient wastewater treatment solutions,joined forces to successfully install a centrifuge centrate treatment process previouslyused only in Europe.

Deammonification, partial nitritation by ammonia oxidizing bacteria (AOB) combined withanaerobic ammonium oxidation (anammox), provides up to 70-90% total nitrogen removalwith a 65% reduction in aeration energy, a 100% reduction in supplemental carbon, andan approximate 50% reduction in alkalinity requirements as compared to traditionalnitrification-denitrification. The DEMON® process is one of several available forms ofsingle-step (in the same tank) partial nitritation-anammox designed for centratetreatment from anaerobically digested Biosolids and operated as a sequencing batchreactor (SBR). While this process had been applied at approximately 30 plants in Europe,it had not been implemented elsewhere in a full scale application, primarily because of therequirements for seeding this process using biomass imported from operating facilities inEurope. The stability of the DEMON® process has improved in recent years with theaddition of a hydrocyclone for selective anammox bacteria retention in the process, andthis improvement resulted in considerably more interest in other parts of the world.

HRSD’s York River Treatment Plant, located in Seaford, Virginia, currently includes a fullyaerobic nitrifying activated sludge system with post denitrification filters. The plant wasthe site of another first that made it a stellar candidate for the DEMON® process.In 2002, HRSD launched at this facility Virginia’s first municipal water reuse project,which required the construction of an SBR. The initiative ended when an adjacentrefinery, the only reclaimed water customer, closed. Consequently, during recent plantupgrades, the SBR and equalization tanks installed to support the reuse project wereretrofitted to serve for centrate equalization and full nitrification. This meant that onlyminor piping needed to be done to install DEMON®, making the project more affordableand sustainable.

The DEMON® process was seeded with 5,000 gallons of concentrated anammoxbiomass by mixing the imported anammox biomass with plant effluent in October 2012.After some minor modifications to the equalization tank were made in November/December 2012, the process achieved operating objectives for ammonia loading andtotal nitrogen removal in early January 2013.

G

HRSD’s York River Treatment Plant, located in Seaford, VA,is the site of the first operating full-scale installation of anyform of anammox sidestream treatment in North America.

The availability of centrate equalization and treatment tanks modified for this purpose in a previous plantupgrade, which were suitable for DEMON® implementation, meant installation required less than 4months. The N-Cycle

The innovation of adding hydrocyclones for selecting anammox bacteria has led to stability of this patent pending DEMON®process.

AOB and Anammox Biomass. The DEMON® process shown duringthe aeration cycle.

Partial Nitritation-Anammox

HRSD York River Treatment Plant Implements Sustainable DEMON®SidestreamDeammonification Technology for Energy and Chemical Savings

• 65% reduction in aeration energy• 100% reduction in supplemental carbon • Approximate 50% reduction in alkalinity requirements as compared to traditional nitrification-denitrification.

5,000 gallons of concentratedanammox biomass was importedfrom Europe to seed the system.

WWW supplied the technology and processdesign, and HRSD installed the equipment, performed minor piping modifications, providedengineering support during construction andnow operates and maintains the DEMON®

sidestream deammonification process and related equipment.