Smarter Dosing for Disinfection

Disinfecting wastewater requires adding enough disinfectant to inactivate enough pathogens to meet permitted concentration. Current flow-pacing methods to achieve this rely on establishing concentration set-points based on worst-case scenarios (i.e., shorter contact time and poorest wastewater quality leading to the lowest disinfectant residual), and controlling such set-point values via the use of local disinfectant concentration sensors, depending on characteristics of the wastewater and volume of flow. These systems can operate with or without feed-forward, model-based flow-pacing. As a result of flow pacing strategy, disinfectant often is overdosed — this occurs whenever flows decrease or better quality influent enters the disinfection tank.