Animal Waste, Water Quality and Human Health

Exposure interventions 305ProblemHigh levels of E. coli in bathing waters have been linked to increased human exposurerisk due to the likelihood of pathogen presence via epidemiological studies. In additionto poor circulation within the beach area and nutrient loading the following pollutantsources were identified: faulty septic systems, wet weather urban and rural surfacerunoff, and industrial discharge. As a result of the influx of contamination, the bathingbeach was frequently closed for lengthy periods of time during the recreationalswimming season.Improvement initiativeThe Upper Thames Region Conservation Authority (UTRCA) in conjunction with theOntario Ministry of Environment and Trojan Technologies installed a polyvinylcurtain and UV light disinfection system to improve water quality in the enclosedswimming area. Water was pumped through intake screens to remove debris, passedthrough UV lamps in a facility onshore to disinfect the water and returned to theenclosed swimming area through two diffusers. The curtain was anchored to thebottom and enclosed some 1600 m 3 of water which was re-circulated every fourhours. The UV system consisted of two reactors, each consisting of a concretechannel housing five modules. Each module contained four lamps for a total of 40lamps in the system (20 lamps per reactor). Water was analyzed weekly for E. coli atseven sites within the enclosed area. UV disinfection resulted typically in a greaterthan 97% reduction in levels of E. coli, even following rainfall events (Figure 8.2).Figure 8.2 Enclosed bathing area and intake for on-shore UV system at Fanshawe Beach,Ontario, Canada.