Annie Jiang graduated from Colorado School of Mines with Bachelor's and Master's degree in Environmental Engineering in 2020. She joined Ardurra Austin as an Engineer-In-Training in July 2021. Annie's area of interest is treatment process design with an emphasis on wastewater treatment. Some of her roles include but not limited to are process design, biological process modeling, and treatment data analysis. Annie is a member of the Water Environment Federation, American Water Works Association, and Water Environment Association of Texas.

• Add Second Speaker

Megan Martin, PE holds a Chemical Engineering Degree from University of Texas and brings over 17 years’ experience in the consulting engineering field. Ms. Martin has designed and assisted in the construction of a wide variety of wastewater treatment processes. Megan also serves as a judge for the WEF and WEAT Operations Challenge Maintenance Event.

Aeration energy often exceeds half a wastewater plant's power demand. Wastewater modeling simulators are potent tools that can save significant time and money in evaluating multiple advanced upgrade alternatives. This presentation includes a wastewater modeling case study yielding substantial savings for three Oklahoma City nitrifying wastewater treatment facilities.

Ardurra evaluated the aeration capacity of three activated sludge facilities in Oklahoma City, including:

1. Chisolm Creek WWTP (11 MGD)
2. Deer Creek WWTP (15 MGD)
3. North Canadian WWTP (80 MGD AADF)

Each facility operates a single-stage nitrification system, and their respective effluent data meet ammonia permit limits. Each facility will unlikely receive a total nitrogen effluent discharge limit in the foreseeable future. However, denitrification has significant benefits, including protecting the stream's water quality and improving secondary clarification through strengthening flocculation particles. Incorporating denitrification can also help operators control undesirable filamentous growth and return alkalinity to the treatment process.

Design of aeration systems and selection of aeration equipment is often done through spreadsheet calculations based on an estimation of specific oxygen requirements. These estimations can be derived through empirical or mechanistic steady state or dynamic process models such as BioWin. Common design practice is to evaluate minimum and maximum month, annual average, and peak day loads and temperatures for model inputs to cover the full range of operational plant flows. The design procedure involves setting the DO to 2 mg/L, and the required airflow is determined based on standard equations.

Steady-state models allow for the development of a blower capacity and the number and distribution of diffusers. Dynamic models allow for fine-tuning sizing through evaluating a facility's dynamic behavior, such as periods of high energy usage or low DO concentration. Dynamic modeling integrates all parts of the treatment process, including controllers and aeration equipment, delivering more valuable information to the designer.

Performing steady state and dynamic modeling allowed us to evaluate the conversion of the conventional activated sludge plants to nitrifying and denitrifying facilities. Our work with the model made it possible to fine-tune blower configurations, make valve adjustment settings, and optimize airflow requirements. Our calculations allowed us to reduce alkalinity feed requirements to control pH and improve settleability while decreasing chemical feed costs for solids handling.

This presentation will discuss the conversion of OKC's three plants from conventional activated sludge to advanced treatment facilities, thereby increasing treatment efficiency and effluent water quality. We examined historical power demand and compared it to projected savings from a new operational protocol aligned with the plants' expected and typical operations. We will discuss our 20-year life cycle analysis and present cost savings of approximately 35 percent.