Dr. Colleen Chan, P.Eng.
Current Research Projects
Title: Development of Low Cost, Sustainable and Locally Produced Treatment Technology for the Removal of Synthetic Organic Contaminant in Drinking Water
Co-investigators: Monica Ip, Jeff Ferraby (Department of Civil Engineering) Dr. Kevin Soulsbury, Betty Zhou (Department of Chemistry)
Many point-of-use water treatment technologies applicable for use in rural communities in developing countries were designed for the purpose of pathogen removal without consideration of synthetic organic contaminant (SOC) removal. However, there is an increasing concern regarding the presence of SOCs in source water, especially in intensive agricultural or industrial areas where large quantities of SOCs are applied and discharged. These SOCs become part of the runoffs into rivers, lakes and leachate into groundwater. Chronic exposure to these pollutants (e.g. through drinking water) can cause significant health problems. The objective of the project is to develop a low cost, locally generated treatment technology, used in combination with point of use household technologies (i.e. biosand filter) such that the removal of SOCs from water is enhanced to a level that is safe for consumption.
Title: Effect of Point-of-Use Household Biosand Filter Inactivity Periods on Effluent Water Quality
Co-investigators: Jay Kim, Monica Ip (Department of Civil Engineering)
Currently over 2 million people depend on the point-of-use household biosand filter for the provision of safe drinking water. Some of these users adopt a nomadic or semi-nomadic lifestyle in which they move to other regions for extended periods of time for work or to farm based on agricultural seasons. As a result, the biosand filters are left inactive in their homes for extended periods of time. Recent field reports from humanitarian organizations (CAWST) have indicated that upon returning to their homes, some biosand filters exhibit a foul smell. As a result of this foul smell, many families abandon the use of the biosand filter. To date, it is not clear what causes the foul smell in the biosand filters after long periods of filter inactivity. It is also not clear how long periods of inactivity would affect filtered water quality, both biologically (i.e. pathogen removal) and chemically (i.e. presence and generation of nitrates/nitrites due to the anaerobic conditions within the filter). This project investigates the effects of biosand filter inactivity periods on effluent water quality (biological and chemical), and provides recommendations to users regarding resuming the use of the filters after long periods of inactivity.
Title: Effects of Biosand Filter Sand Grain Size, Hydraulic Loading Rate and Residence Time on Effluent Water Quality
Co-Investigators: Kyle Neufeld, Stevan Gavrilovic (Department of Civil Engineering)
The efficiency of pathogen removal is dependent on the operating conditions and the design parameters of the biosand filter (i.e. grain size, hydraulic loading rate, batch residence time). Current biosand filters require sand gradation with specified effective size and uniformity coefficient which yields a desired hydraulic loading rate optimal for pathogen removal. In practice, achieving the specified sand gradation is often a labour intensive sand preparation process, and requires specific types of sieves which may not be readily available in some rural communities. In places where the specified sand gradation cannot be met (i.e. a coarser sand is used instead of the finer sand specified), a practical solution may be to modify other physical and operational components the filter such that the hydraulic loading rate criteria is met. However, it is not clear what effects this will have on the filter's pathogen removal efficiency. The objective of this project is to provide a recommendation on whether modifications to the biosand filter can be justified. Effects of filter sand size, hydraulic loading rates and batch residence time on effluent water quality were investigated in this project.
Title: Optimum Diffuser Design for the Biosand Filter
Co-investigators: Sam Jones, Darien Cusworth (Department of Civil Engineering)
The biosand filter consists of several components, one of which is a diffuser plate. The diffuser plate is used to dissipate the kinetic energy of water poured into the filter. The energy dissipation is necessary to reduce the impact and disturbance to the top biological sand layer (biolayer) - an important layer for pathogen removal in water. The objective of the project is to establish the optimum diffuser plate design for the biosand filter. The project is carried out in two phases. The first phase involves the development of several diffuser plate configurations, and the investigation of the relationship between kinetic energy dissipation and the disturbance of the top biolayer. The second phase involves the investigation of water quality improvement using the diffuser plate developed from phase 1.