The Client's Needs
The existing wastewater treatment plant (WWTP) consisted of a series of four lagoons. The WWTP was landlocked with minimal land area for expansion.
A number of technologies were considered for upgrading the WWTP. After a six-month pilot study held in the winter of 2004-2005, an AnoxKaldnes™ Moving Bed Biofilm Reactor (MBBR) was deemed to be the best alternative – the major advantage being its small footprint.
The AnoxKaldnes™ MBBR operates as a stand-alone treatment process. There is no return activated sludge (RAS) from a secondary clarifier, thereby operator intervention and maintenance is minimized. In the case of Ste-Julie, a full scale MBBR™ was installed and commissioned in 2007. Even with temperatures as low as 3°C, the average ammonia effluent concentration was 3.9mg/L, down from an average influent concentration of 16.2mg/L.
The study determined that the MBBR solution not only eliminated COD and BOD, but also nitrified the water coming in. The main objective of the pilot study was to demonstrate the capability of the MBBR process to eliminate organic matter in a separate stage and to reach a level of BOD of less than 29mg/L after a settling period of 30 minutes. The results of the study were positive; the average concentration of settled BOD being of 26mg/L after 30 minutes of settling with a total BOD5 loading of 3.29g/m2-day.
Over the past 40 years, the City of Ste-Julie (Quebec) has enjoyed a tremendous growth rate, effectively multiplying its population 15 times over. The subsequent increase in pollution loading, coupled with more stringent effluent standards, made the upgrade of the existing wastewater treatment facility virtually unavoidable.