Water Treatment Plant Operational Resilience – An Evaluation of Powdered Activated Carbon Usage for Seasonal Tastes and Odors Control in Relation to Climate Change and Source Water Quality

Abstract

Water treatment utilities adapt daily to intake water quality fluctuations caused by weather and other factors. Taste and odors are not health concerns, but consumers relate their presence to unhealthy drinking water. Climate change impacts are expected to affect water quality and increase taste and odors. Therefore, water utilities will need to adapt to ensure that they are able to continue to meet the expectations of the consumers. A survey of Tennessee water treatment plant operators indicated that operators may rely heavily on the robustness of the plants and operator experience, which could pose challenges in planning for the future. Predictive tools for understanding climate change impacts are needed to prepare for the future. Simple linear regression and logistic regression models were developed for two water treatment plants located in Nashville, TN. The models were developed to describe the relationship between powdered activated carbon use and ambient air temperatures, taste and odor compounds, and intake water temperature. Simple linear regression did not meet the performance criteria. Logistic regression modeling met the criteria and was used to predict climate change impacts on taste and odor compound presence and powdered activated carbon usage as a function of ambient temperatures for the projected 2030-2060 (future mid-century), and 2069-2099 (future) time periods. The predictions, on average, indicated that climate change impacts have occurred as of the study period (2007-2016). By the future time period (2069-2099), the season for taste and odors and powdered activated carbon usage will likely be extended to most of the year (>0.1000 probability) reaching a critical level of concern for five or six months of the year (>0.9000 probability). A method was developed to estimate the powdered activated carbon needed for treatment as temperatures increase. A low estimate of the climate change impact is to increase powdered activated carbon usage, on average, by approximately 30% by the future time period (2069-2099). This study was a first attempt to assist water utilities in planning for future taste and odor management under projected climate changes using statistical modeling.