Session 22B: Facility Operations and Maintenance: Process Optimization
3:00pm - 3:45pm
Real-Time Process Controls to Improve Operational Sustainability: A Study of Two East Coast Wastewater Facilities
Hazen and Sawyer, United States of America;
The purpose of this presentation is to summarize real-time process control programs and historical data from two east coast wastewater facilities to illustrate benefits and challenges associated with using advanced process control programs for nitrification, denitrification, and solids separation. The programs include ammonia-based aeration control (ABAC), aerobic solids retention time control, optimized dissolved oxygen (DO) control, chemical nutrient-pace dosing, ammonia-based-load equalization, and secondary clarifier guidance. In addition to presenting positive impacts such as cost and time savings and process optimization, operator feedback on challenges including calibration, cleaning, and troubleshooting of on-line analyzer instruments will be included in the presentation.
Operating data post-program implementation at the Neuse River Resource Recovery Facility (NRRRF) and North Durham Water Reclamation Facility (NDWRF) was analyzed to evaluate changes in operational efficiency and cost savings resulting from real-time process controls.
For example, after implementation of ABAC, NDWRF optimized the ammonia setpoint to make BNR basin nitrification more reliable. Effluent TN was reduced by 0.6 mg/L (from 2.9 to 2.3 mg/L) by allowing increased simultaneous nitrification and denitrification and less DO entering the anoxic zones. Also, the mass of nitrate removed in the second anoxic zone per pound of glycerin added increased from 2.1 to 3.0 lb nitrate/lb glycerin, illustrating how ABAC also made denitrification more efficient.
NRRRF has also seen significant improvements in denitrification and carbon savings following implementation of ABAC, nutrient-paced carbon feed, and ammonia-based load equalization. Overall, nitrate concentrations at the end of the aerobic zone have decreased from 10 mg/L in 2017 to 8.5 mg/L in 2018, and methanol use has decreased by 32%.
NRRRF and NDWRF have optimized their process to achieve reduced effluent total nitrogen concentrations and decrease operating cost with several real-time process control programs. These low-cost solutions are helping utilities operate more efficiently with reduced chemical and energy demand.
3:45pm - 4:30pm
Providing Onsite Laboratory Support to Improve Treatment Facility Operations
Clean Water Services, United States of America;
Clean Water Services (CWS) operates a centralized Water Quality Laboratory (WQL) to support efforts across the District. Every year, over 30,000 treatment plant, surface water and industrial samples are sent to the WQL where more than 140,000 analyses are performed. The centralized approach is efficient and cost-effective. However, this approach also disconnects laboratory personnel from the context of the samples and slows turnaround time between sample collection and when results are available for process decision making.
Over the past few years, CWS has implemented a different strategy to improve the support the WQL provides to the Wastewater Treatment Department. The relocation of a laboratory specialist from the centralized lab to the Durham Treatment Facility has facilitated collaboration between multiple departments within CWS including the WQL, Operations, Electrical & Instrumentation, and the Technology, Development and Research group. This collaboration and face-to-face communication has allowed for more rapid and effective troubleshooting of online analyzers, as well as standardization of online instrument maintenance and validation.
The laboratory specialist is key to the standardized approach to instrument maintenance and validation. The laboratory specialist serves as the instrument champion with responsibility to:
This standardized approach has resulted in greater instrument accuracy and dependability and increased CWS reliance on online instruments. Shifting the structure of the WQL to provide onsite support has been a success. Process control data is available faster, instrumentation is more reliable and coordination between work groups has improved. This presentation will detail the role of the onsite laboratory specialist, summarize the CWS standardized approach to instrument operation, and provide lessons learned through the development of this new role.