Hydrological Characterization and Treatment Performance Assessment of a Natural Tundra Wetland Receiving Effluent from a Single-Cell Wastewater Treatment Exfiltration Lagoon

In light of the recent introduction of proposed Canadian federal wastewater effluent discharge regulations, research is being conducted on northern treatment systems in recognition of the unique challenges that a northern climatic environment pose. The Coral Harbour, Nunavut, wastewater treatment site consists of a single-cell lagoon that dynamically exfiltrates effluent into a natural tundra wetland treatment area. Natural tundra treatment wetlands may be a viable option for wastewater treatment in remote northern Canadian communities due to their passive and low maintenance operation requirements. The objectives of the study are to conduct a treatment performance and risk assessment, and develop an approach for modeling the hydrology and water quality aspects of the natural wetland treatment area. Many modeling techniques are available; however, a non-ideal flow chemical reactor model may be the most applicable to the site conditions. Data collection has included physical characterization, hydrological and hydrogeological monitoring, and treatment performance sampling of the wetland. Preliminary results have shown that the hydraulic loading rate of effluent on the wetland is highly dynamic, depending on seasonal factors with greater loading occurring during the spring melt period. The hydraulic retention time (HRT) of the natural treatment wetland is also highly variable depending on the period of observation; generally, the HRT was much shorter during the spring melt when flows into the wetland were high. Treatment performance (in terms of concentration reductions) of the natural treatment wetland was observed to be reduced in June compared to September, attributable to decreased retention time and comparatively lower amounts of dilution.