Aerated Lagoon Enhancements to Achieve NPDES Compliance
The City of Norway’s aerated lagoon wastewater treatment system doesn’t meet new NPDES permit limits for ammonia-nitrogen and E.coli. To achieve reduced limits, a NitrOx® system and UV disinfection system will be added. The NitrOx system consists of a
series of aerated concrete tanks with floating media and in-tank heaters. The heaters help maintain the optimum water temperature during winter to facilitate proper ammonia-nitrogen removal. The NitrOx system occupies a small footprint and is installed between the aerated lagoons and the final settling cell.
Snyder & Associates evaluated the city’s existing treatment process of aerated lagoons followed by manmade wetlands. It was determined that the most economical options would be to construct an ammonia removal process while utilizing the existing aerated lagoon treatment system. Other wastewater treatment options were analyzed in detail, but the economics and relative maintenance requirements of the NitrOx process were ideal. UV disinfection is being planned to meet compliance with E.coli discharge limits.
Some of the challenges Snyder & Associates helped this project overcome include site constraints, construction within a floodway, and sizing the project to incorporate wastewater from an existing industrial facility. In addition to the unique process solution, we also helped the City of Norway evaluate options for solar power use to decrease an anticipated rise in electrical bills due to the NitrOx in-tank heater system.