Novel enhanced primary treatment (EPT) of combined sewer overflow (CSO) using combinations of oxidants and coagulants

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Improved municipal water management is a critical element in securing a sustainable ecological future for Canadian lakes and rivers which cover about 12% of the surface area of Canada. Combined sewer overflows (CSOs) contribute a significant amount of pollutants especially at heavy wet weather conditions which may be more frequent in the coming years due to the climate change phenomenon. Current practices of bypassing the CSOs or partially treating these flows through primary treatment enhanced only by coagulants have elevated the concentrations of some parameters like total suspended solids (TSS) and E.coli beyond the regulatory requirements of safe discharge to the river. This violation to the regulatory requirements can pose dangerous consequences to the receiving aquatic environment organisms. In addition to the regulated pollutants, micropollutants (MPs) and nanomaterials (NMs) found at elevated concentrations in CSOs as a result to their extensive usage in a wide range of products can pose risks on humans, fish and other aquatic life. Consequently, their fate and removal mechanisms should be assessed, and strategies to reduce their concentrations prior to their release should be developed. In order to further enhance the treatment of CSOs, there is an essential need to enhance both the settling and the oxidation/ disinfection capabilities in primary sedimentation tanks. Chemical additions considered in this study will include ferrate (Fe(VI)) which is a promising dual oxidant/coagulant and peracetic acid (PAA) as an oxidant applied in conjunction with coagulants such as aluminum sulfate, polyaluminum chloride, or ferric chloride. The proposed NSERC Collaborative Research and Development (CRD) Program will assist decision-makers to adopt sustainable development strategies based on the simulation of actual conditions and the predictions of the impact of different pollutants in CSOs on the environment. As a result of this CRD Program, highly qualified personnel will be trained with multidisciplinary expertise that will strengthen Alberta's and Canada's capacities in wastewater treatment management.