Removal of pathogenic and indicator bacteria from dairy wastewater using an ecological treatment system.

In the quest to improve the sustainability of water treatment options, plant-based systems, such as wetlands and ecological treatment systems, have become a promising alternative. To date, most of the research on ecological treatment systems has focused on the ability of these systems to remove excessive nutrients, turbidity and BOD from wastewater. However, wastewater is the primary source of fecal contamination in aquatic ecosystems; therefore another factor key to making these systems successful is ensuring their ability to remove pathogens. This study assessed the ability of an ecological treatment system to remove total coliforms and E. coli from dairy wastewater. Total coliform and E. coli data was collected from the ecological treatment system located on Waterman Farm (WETS) at The Ohio State University. A three phase dosing experiment was conducted during the summer and early fall of 2005 to assess the capacity of the WETS to remove pathogens from wastewater. Wastewater was diluted with wellwater at a ratio of 1:3 during the month of July, in August the ratio of wastewater increased to 1:1, and in September increased to 2:1. Regardless of wastewater concentration, total coliform and E. coli concentrations were consistently reduced by at least 95% from influent to effluent of the WETS, with over 60% of the reduction occurring in the first two reactors. Pathogen concentrations were negatively correlated with DO and NO3 concentrations and positively correlated with TSS concentrations. These results indicate that ecological treatment systems have the potential to successfully remove pathogens from wastewater.OARDCUSD