Stricter regulations forced the town of Johnstown, Colorado to examine alternatives for an upgrade to their existing system.
Originally, the Johnstown site consisted of a series of three lagoons built in the 1950’s, with the most recent upgrade taking place in 1980. The city was faced with expanding their treatment capacity, along with meeting lower ammonia limits. The effluent discharge standards required the city to meet the new ammonia limits year round.
The wastewater temperature in the plant is low (<7°C/ 45°F) during winter making it difficult to nitrify on a consistent basis. In order to meet the nitrification limits, the city had two options to choose: build a new activated sludge plant, or use their existing facility and install an AnoxKaldnes™ LagoonGuard™ treatment system. The MBBR process was estimated to cost 50% less than the activated sludge alternative.
The city chose to install the AnoxKaldnes LagoonGuard. Two trains of two Moving Bed Biofilm Reactors in series were added after Lagoon 2, along with a DAF at the end of Lagoon 3.
City of Johnstown, CO - case study