Modeling the Resilience Performance of Houston’s Wastewater Treatment Plant under Wet Weather Conditions

Abstract

With increasing severity of wet weather events due to a changing climate, many municipal wastewater treatment plants are grappling with challenges in maintaining effective flow and effluent management. Compounded by aging wastewater infrastructure, it is imperative to enhance the resilience of wastewater systems to cope with the increasing intensity of wet weather events. This study employs a robust modeling framework using the Benchmark Simulation Model 2 and provides an analysis of the resilience performance of a wastewater treatment plant in Houston, Texas, in response to synthetic storms of varying intensities. It was shown that increased severity in wet weather results in decreased resilience performance with ammonia removal as the performance metric. Potential sewer overflows are identified in the absence of equalization basins under all synthetic storm scenarios. Furthermore, the sewershed, characterized by a high population density and low economic capacity, renders communities within it more susceptible to the adverse effects of potential sewer overflows. While effluent ammonia concentration remains within permissible limits due to the dilution effect, the substantial discharge of untreated ammonia loads into the receiving river may pose risks to the expansion of the hypoxic zone in the Gulf of Mexico. Our study addresses a critical gap in the quantitative assessment of US wastewater systems’ resilience performance under varying severities of wet weather. Overall, it highlights the urgent need to evaluate the resilience of existing wastewater systems, particularly in the context of evolving climate conditions and aging infrastructure.