Wastewater Treatment Plant Disinfection and Ammonia Removal Improvements
Maximizing the Potential
In order to anticipate challenges and quickly solve problems for the city's wastewater treatment plant, it was imperative to plan ahead of pending regulations imposed on the plant's discharge to the Missouri River. Regulatory requirements through Great Falls' new Montana Pollutant Discharge Elimination System (MPDES) permit, required improvement designs that would bring critical discharge permit limits for metals discharge, flow metering, ammonia, and E.coli into compliance.
Even before new disinfection and ammonia removal designs to meet the regulations started, an extensive baseline river sampling survey both upstream and downstream of the outfall was developed. With this baseline sampling done, the metals limits could be eliminated as a concern. The design of new facilities needed to maximize treatment technologies for disinfection and ammonia removal were used to get the desired discharge permit requirements while providing for accurate influent and effluent flow measurement.
Design improvements included reconfiguration of existing aeration basins into two biological reactors (bioreactors) for reduction of ammonia and nitrogen and a new ultraviolet (UV) light disinfection system within the existing disinfection tank. The bioreactors were designed so that a single sensor controls oxygen feed to both reactors, minimizing the need for expensive analytical and controls equipment. This process also utilizes denitrification, the use of oxygen in nitrate, to minimize the amount of dissolved oxygen required to achieve treatment limits. The implementation of the denitrification process optimized energy usage and cost.
Additional considerations were also taken to visually blend the new facilities since the wastewater treatment plant is located adjacent to an active pedestrian trail. Designers matched brick fascia elements to blend into existing infrastructure while masking the industrial nature of the facility.
- 2015 - First Place, Best Projects Award, Engineering News-Record Mountain States