Process Roadmaps to Low DO Operations - Lessons Learned from a North American Survey on Suboxic and Low DO Activated Sludge Facilities

Facilities throughout the United States are successfully implementing low dissolved oxygen (DO) and suboxic nutrient removal (SBNR) operations using a variety of plant configurations and controls strategies to decrease energy consumption while achieve high effluent quality standards. As part of a Department of Energy project, several facilities participated in workshops to identify common operational strategies and challenges for low DO/SBNR operational. From the workshop, it was determined that successful low DO/SBNR systems can be achieved with a variety of aeration process configurations and controls strategies. Aeration demand and blower turndown were the largest obstacles in achieving low DO operations. Instrumentation is key: understanding which probes are appropriate and the importance of probe location can significantly influence process performance. In addition, Los Angeles County Sanitation Districts is implementing SBNR operations at the Pomona Water Reclamation Plant which will provide real-world guidance on SBNR execution and operations.