The effectiveness of slow sand filters to treat Canadian rural prairie water

Abstract

The following manuscript provides a technical review of slow sand filters (SSFs) as well as two case studies from the province of Saskatchewan, Canada in which an optimized technology has been successfully designed and implemented to produce high quality potable water for very small populations. Renewed interest in SSF systems for small communities has resulted in enhanced plant and filter design, improved operating procedures for increased efficiency and expanded range of acceptable raw water quality input and an overall low maintenance system design. Despite some limitations to the use of SSFs, recent design modifications and improvements for operation and maintenance of SSFs have expanded their application to a broader range of contaminants under highly variable environmental and operating conditions. The flexible and modular design options inherent to SSF systems, along with the modifications in expanded application, make SSFs highly attractive for potable water treatment in rural and remote regions. The SSFs designed and tested in Saskatchewan are modular polyethylene systems that include pre- and posttreatment processes such as ozone oxidation, roughing, and biological activated carbon (BAC) filters to provide significant reductions in turbidity, heavy metals, colour, and organics.