Microbial dynamics within passive wastewater treatment systems in northen climates

Domestic wastewater treatment in rural and remote regions of Canada presents significant challenges. Conventional mechanical wastewater treatment plants are typically not an appropriate technology in these regions. In these situations, passive wastewater treatment systems are widely used for management of wastewater generated from individual residences or small communities. The principal types of passive systems used in Canada include soil or peat-based filters, wetlands and lagoons. Advantages of passive systems include relatively low capital and operational costs, and reduced maintenance requirements. Disadvantages of passive systems, however, include larger spatial footprints and reduced reliability. The reliability, or variability in treatment performance, of passive systems is a pertinent issue for Canada, due to our widely varying, and sometimes extreme, climate. With respect to the protection of public health, the release of pathogenic microorganisms from passive wastewater treatment systems is a primary concern. The overall, long-term goal of this research program is to develop the ability to characterize and manage the risk associated with the release of pathogenic microorganisms from passive wastewater treatment systems operating in Canadian climates. In this research we will assess and compare the migration of fecal indicator organisms and pathogenic bacteria in passive systems typically used in both Southern and Northern regions of Canada.This study will provide unique information on the genetic diversity of E. coli populations within passive wastewater systems and an assessment of (i) strain-specific transport potential, and (ii) naturalization phenomena. This proposed research will also provide much needed knowledge with respect to the microbial treatment performance of lagoon and wetland systems operating in Canada's Far North. Ultimately, this research will lead to the development of design guidelines and improved monitoring programs for passive systems treating domestic wastewater in all regions of Canada.