Annular reactors and UV collimated beam apparatus for research of integrated disinfection of drinking water

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The control of microbial regrowth in distribution systems is one of the primary concerns for utilities in the drinking water industry.  The formation of clusters of bacteria, or "biofilm", on pipe surfaces can lead to an increase in pathogenic microorganisms, biocorrosion of pipe material and headloss in the pipe system.  Disinfection is often the key step in controlling biofouling in pipe systems.  Due to increasingly stringent regulations on disinfectants and their byproducts (i.e., Stage II D/DBP Rule, USEPA), suppliers are struggling to maintain a balance between residual protection, control of biofilm formation and compliance with drinking water standards.It is plausible that disinfectants in combination can form an integrated disinfection strategy that enhances removal of microbial pathogens entering the distribution system.  Although research in the area is limited, preliminary studies conducted by Dr. Rand have shown that synergistic benefits exist between UV light and chlorine-based disinfectants in the reduction of bulk water and biofilm bacteria.  Utilities in the drinking water industry could benefit from synergy by achieving higher removal of bacteria without increasing chemical disinfectant dose.  However, much more research is required before synergy becomes an accepted and utilized theory.Dr. Rand is interested in simulating distribution systems using alternative disinfection strategies to further the research on synergistic effects using bench-scale equipment.  Annular reactors (ARs) are widely accepted in the drinking water industry as a tool to simulate distribution systems due to their unique ability to promote biofilm formation while independently controlling hydraulic retention time and shear stress.  Collimated UV beams are an efficient way to achieve accurate dosages, and no such equipment currently exists in Atlantic Canada.