Benefits of Wastewater Process Modeling for Planning, Project Development, and Management


  • Phill Yi, Wendell Khunjar, Katya Bilyk, Ron Latimer, Paul Pitt - Hazen and Sawyer

As water resource recovery facilities (or wastewater treatment plants) move toward ever more stringent effluent limits there is greater demand on utilities to better manage existing assets in order to meet these limits. From a treatment plant perspective, this could mean additional capital investments to plants that have already undergone significant upgrades in recent years to achieve low effluent nitrogen and/or phosphorus limits. It is imperative to proactively plan and develop projects that will allow facilities to achieve the required and anticipated levels of treatment while saving costs. One tool that has been successfully implemented to achieve such goals are wastewater process models. For example, a facility in North Carolina was recently rerated to a 25% higher flow without having to construct additional biological nutrient removal tanks. Process modeling was used to optimize the configuration and operational strategy of the existing process.

Wastewater process models have been used successfully in planning and project development in several applications. For example, process models can and have been used to evaluate and optimize plant performance (i.e. ammonia-based DO control, carbon feed optimization, seasonal operating methods, tools of operations and training) as well as plan for future upgrades, provide training to operations, evaluate means of energy curtailment, and minimize chemical consumption. Use of process modeling in such applications can benefit plants and avoid pitfalls by more accurately estimating potential chemical/energy savings and evaluating the benefits, impacts, and feasibility of planned upgrades.

This presentation will provide an overview of applications and use of process models as it relates to planning, project development, and asset management. It will also cover different available software platforms for process modeling, typical procedures for model development, and several real-world applications at different water resource recovery facilities. Two examples that will be included are:

(1) Utility A developed several process models for their seven plants, which were then used to create an Operations Tool (“flight simulator”) for training, management of consumables (energy, chemicals, etc.), and for business case development for plant upgrades and operational changes.

(2) Utility B utilized process modeling to identify optimal process configurations during warm and cold weather to minimize chemical costs and effluent nutrient discharges.

For more information, please contact the author at

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Horizons Fall 2017 (pdf)

Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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