Ozone treatment of combined sewer overflow (CSO) for disinfection and micropollutant control

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Combined sewer systems are designed to collect stormwater runoff, domestic sewage, and industrial wastewater in the same pipe and bring it to the local wastewater treatment plant (WWTP). During heavy rain and snow storms, combined sewers receive higher than normal flows. WWTPs are unable to handle these flows that may be as much as 5 to 6 time the plant's design capacity. Therefore, a portion of the excess stormwater and untreated wastewater, also called combined sewer overflow (CSO), has to be diverted to the receiving environment with little to no treatment. The CSOs are used to alleviate the overloading of the combined sewer system to prevent sewer backups in residential and commercial buildings and local streets. However, CSOs can impact the water quality and environmental ecosystems in the receiving water bodies if they are discharged into rivers without receiving proper treatment. CSOs may contain dissolved contaminants such as pharmaceuticals and personal care products, particulate organic matter loads, bacteria and viruses. Therefore, there is an urgent need to enhance the treatment of CSOs to reduce their environmental impacts. The proposed NSERC Collaborative Research and Development (CRD) Program will conduct a comprehensive fundamental and applied research in the area of municipal wastewater, with a focus on a deep understanding of ozonation in terms of process fundamentals, treatment mechanisms, and practical applicability for CSO treatment. The overall objective of the proposed CRD Program is to develop an effective ozone-based treatment approach for the safe release of treated CSOs into the environment. Using ozonation or catalytic ozonation as disinfectant and oxidant may be a viable option to simultaneously enhance the disinfection capabilities to meet the regulatory requirements and target micropollutants that are present in CSOs. This NSERC CRD program is a major advancement in wastewater treatment by providing an enhanced ozone-based treatment approach, aiming to improve the overall quality of the discharged CSOs into the environment and promote the protection of the environment and human health in Canada.