Amphidrome® ColdNite® System

Cold Temperature nitrification for lagoons and other underperforming WWTFs

Polishing the WWTF effluent with this system uncouples the solids residence time (SRT) from the hydraulic residence time (HRT) providing a large population of volatile solids (VS) in a small footprint.

The process utilizes a biologically active filter (BAF), also referred to as a submerged attached growth bioreactor (SAGB) because the media is always submerged in the process flow.  The two primary advantages of SAGBs are the high biomass concentrations, equivalent to 7,000 – 18,000 mg-VS/l, that may be achieved, and the short hydraulic retention time (HRT),


which result when media with a high specific surface area is used.   The media also provides physical filtration and therefore the need for solids separation after the biological treatment process is eliminated.  Solids associated with biological growth and algae are backwashed out of the filter and sent back to the head end of the facility.

After a yearlong pilot that produced fractional ammonia with an influent temperature of 3.3º C, Waverly, PA selected the Amphidrome® ColdNite® system to upgrade their 0.5 MGD lagoon process in lieu of designing a new WWTP.

The Waverly system went into operation in 2014 and has proven to be a cost-effective addition to the Township’s existing treatment facilities for nitrification during cold temperature, weather transition periods, and high peak flows.