Assessing the Potential Causes of cBOD and TSS spikes in Influent Wastewater at the Miami-Dade’s Central District WWTP

The Miami-Dade Water and Sewer Department (MDWASD) operates the Central District Wastewater Treatment Plant (CDWWTP), which has a capacity of 143 millions of gallons per day (MGD). This plant has two parallel treatment trains that receive influent wastewater from different portions of the collection system. CDWWTP has experienced several operational performance challenges attributable to aging infrastructure and changes in the raw influent wastewater characteristics. This has resulted in an observed peak influent concentrations for total suspended solids (TSS) and carbonaceous biochemical oxygen demand (cBOD) several times higher than design criteria, thus impacting the level of service. MWH conducted a characterization of major influent wastewater streams to the CDWWTP to establish the causes of the concentration spikes, and propose mitigation measures from an operational standpoint. Results indicate that spikes are due to high concentrations in areas of the collection system from sludge discharges originating at another treatment plant, and distribution of flows between the plants at the CDWWTP.