City of Toledo Bayview Water Reclaimation Plant Pathogen Study

Funding Organization: City of Toledo
Project Duration: 2011-2021

During storm events in areas with combined sewers, the volume of water entering the sewage treatment systems may exceed the volumetric capacity of the system.  Excess volume is then discharged either partially treated or untreated to surface waters.


The City of Toledo Bayview Water Reclaimation Plant has expanded its treatment process to include a high rate clarification (ballasted flocculation) treatment technology to address this issue.  In the past, the performance of most systems has been evaluated by examining reduction of fecal indicator organisms, such as total coliforms, fecal coliforms, or Escherichia coli.  

However, most fecal indicator organisms are bacterial and may not best represent the reduction of viral and protozoan parasites. This study is designed to improve understanding of the effectiveness of the high rate clarification treatment in regard to pathogenic organisms. In this study, both the high rate clarification and conventional wastewater treatment process trains are sampled and examined for the presence of selected pathogens to evaluate pathogen removal. 

Methods for pathogen detection were selected to evaluate viable organisms that pose a potential health concern if discharged to surface waters. Selected organisms include the pathogens Salmonella, Campylobacter, Cryptosporidium, Giardia, and Adenoviruses as well as indicator organisms Enterococcus and coliphage (F-specific and somatic).