Optimizing a Chemically Enhanced Primary Treatment Process for Operational Decision Support

Abstract

The Wastewater System Effluent Regulations set national effluent water quality standards for wastewater treatment facilities in 2015. This stated effluent discharge limits of less than 25 mg/L for both total suspended solids (TSS) and carbonaceous biochemical oxygen demand (cBOD5). This led to a collaboration between Dalhousie University and Halifax Water to optimize treatment at the Dartmouth Wastewater Treatment Facility (DWWTF). The goal of this study was to provide data-driven decision support for operations at the DWWTF to optimize TSS removal. This is the first step prior to the implementation of a secondary biological treatment process to minimize the subsequent solids load and allow for the target of cBOD5 removal. The study resulted in the creation of two decision trees that may be refined and used for operational decision support regarding optimal chemical dosing during average daily flow (< 3750 m3/h) and average wet weather flows (> 3750 m3/h).