Investigation of Cryptosporidium parvum and Giardia lamblia in wastewater effluent

This thesis concerned developing methods for evaluating the effectiveness of ultraviolet (UV) reactors operating under field conditions for reducing the infectious potential of protozoan parasites present in secondary wastewater effluents. Field studies were conducted at two wastewater treatment plants, one operated by City of Edmonton and the other operated by City of Kelowna. The infectivity of Giardia lamblia cysts recovered and concentrated from wastewater before and after UV treatment was examined using a Mongolian gerbil model. The probability of gerbils inoculated with concentrates collected from downstream of the UV reactors relative to gerbils inoculated with concentrates collected from upstream of the UV reactors was 13 percent. Furthermore, the severity of infection in individual gerbils was lower in the UV downstream samples relative to the UV upstream samples. The findings suggest that the infectivity of protozoan parasites such as Giardia lamblia may be reduced in operating wastewater UV reactors but is not necessarily eliminated.