Performance of sewage treatment plants and impact of effluent discharge on receiving water quality within an urbanized area

In Brazil, wastewater treatment coverage is low. Even when treatment is carried out, many municipalities cannot achieve adequate levels of contaminant removal, and the usual practice of releasing raw or treated domestic effluent into water bodies remains. Thus, this pollution source puts pressure on water resources, compromising downstream uses of the disposal. This study has two aims: (1) to evaluate the performance of sewage treatment plants and (2) to determine the impact of discharging treated effluent on the water quality of receiving water bodies located within an urbanized area in the Velhas River basin, Minas Gerais State, Brazil. Monitoring data from raw wastewater were compared with typical ranges reported in literature, and effluent concentrations were compared between plants. The monitoring data of the receiving water bodies collected at points upstream and downstream of each disposal were statistically compared. Different performances between the systems and significant alterations in the receiving bodies resulting from the discharge of the treated effluents were found.