Full-Scale Demonstration of Continuous AvN Control: What Did We Learn for BNR Optimization?

The main purpose of this study is to demonstrate applicability of AvN control to reduce energy and chemical requirements for a carbon starved 15.7 MGD BNR system at Pueblo, CO required to meet nitrogen and phosphorus limits. The intermittent AvN control has been demonstrated for efficient shortcut nitrogen removal (Regmi et al., 2014 and Regmi et al., 2015) at a pilot-scale. Consequently, there has been a desire to implement AvN at full-scale systems. However, implementation of intermittent aeration with existing aeration system is not trivial and would require major modifications. Hence, in this study a simpler and more practical alternative based on continuous aeration AvN control as an add-on to the existing DO control is tested at full-scale to achieve BNR goals (TIN < 15 mg/L, TP < 1 mg/L as annual average). At Pueblo wasting is performed via hydrocyclone which has resulted in densification (Regmi et al., 2019). Therefore, a unique opportunity was presented to evaluate two very promising intensification technologies – densification with external selector (hydrocyclone) with the AvN control in concert. This paper includes insights from a comprehensive science-based investigation to shed light on i) Aeration savings ii) nitrification rates iii) anoxic P uptake iv) impact of densification on low DO operation as result of AvN control.