Transforming Corrosion and Odor Management Through Data-Driven Sewer Process Modeling

Many utilities face significant corrosion challenges in their sewage collection systems caused by hydrogen sulfide. These corrosion issues, and often associated odor problems, are increasing due to stricter industrial waste controls (heavy metals), widespread drinking water conservation efforts, and the shift toward larger, centralized wastewater treatment facilities. These trends often result in more wastewater with a low dissolved oxygen concentration resulting in conditions conducive for sulfide generation, contributing to extensive infrastructure damage-costing hundreds of millions of dollars and, in some cases, leading to sewer collapses in densely populated areas. Traditionally, utilities manage odor and corrosion reactively, relying on temporary or expensive interventions. Identifying the underlying causes remains difficult, partly because reliable methods for predicting corrosion and infrastructure failures have historically been limited by both the complexity of the processes and the lack of suitable computational tools. Sewer process modeling provides a powerful, proactive approach for understanding system-wide behavior and evaluating mitigation strategies. Before such modeling tools were available, utilities determined the most effective chemicals and doses for odor control through costly, time-consuming trial and error field testing. In contrast, comprehensive sewer process models enable instant evaluation of treatment chemicals, prediction of impacts on downstream treatment plants, and estimation of airflow requirements for vapor-phase treatment. This presentation will introduce conceptual sewer process modeling and demonstrate its benefits and potential cost savings. Several case studies will be presented, including:

System wide optimization of chemical dosing locations for odor and corrosion control.
A project where modeled ventilation airflows informed dosing strategies that reduced odor control chemical costs by $430,000 per year.
An example showing how the model helped evaluate and select an alternative solution that directly addressed the source of persistent odor issues to improve community relations.

Attendees will gain an understanding of the modeling approach, practical applications, and opportunities for substantial cost and operational efficiencies. Figure 1 - An example from a case study - once upon the time there was a maintenance hole. Figure 2 - Case study illustrating a system-wide holistic approach to identify whether issues are being local or systemic. A local problem applies to a small area of the catchment, one tributary of the collection system or one single pump station and has an end point. A systemic problem applies to all parts of the catchment and/or gradually increasing along with the collection system. A systemic issue might be caused by multiple minor inputs causing significant problems in the carrier as it travels downstream. The purpose of this classification is to narrow down the possible solutions that can be applied to the problem, thus arriving at the preferred option more expediently. Figure 3 - Case study identifying priority zones for cost-effective mitigation.