Combining continuous flow aerobic granulation using an external selector and carbon-efficient nutrient removal with AvN control in a full-scale simultaneous nitrification-denitrification process

Abstract

The James R. Dolorio Water Reclamation Facility in Pueblo, Colorado, uses AvN aeration controls to lower aeration energy while promoting carbon-efficient nutrient removal and hydrocyclone-based wasting to achieve SVI improvements and process intensification. The results from the full-scale installation showed that hydrocyclone-based wasting helped improve settling characteristics by reducing the SVI from 200 ± 52 mL/g to 83 ± 22 mL/g within weeks of operation. PAO and nitrifiers were preferentially retained in dense flocs and granules, while lighter heterotrophic and filamentous organisms were preferentially wasted, thus uncoupling the SRT of these two fractions relative to the overall SRT. The SRT was estimated at 14.4 ± 3.4 days for dense aggregates and 7.1 ± 2.3 days for lighter flocs. The use of AvN control with continuous low DO conditions resulted in low DO conditions (< 0.3 mgO2/L) reducing air demand by 50% while providing excellent nitrogen (effluent TIN < 11 mgN/L) and TP removal (effluent TP < 1 mgP/L) at low primary effluent COD/N ratio of 6.0. The presence of comammox was demonstrated through molecular analysis, while ex-situ batch tests revealed the presence of DPAO, which could have attributed to the energy and carbon-efficient biological nutrient removal.