Evaluation of Pathogen Removal from Dairy Wastewater Using an Ecological Treatment System

Abstract

Ecological treatment systems can provide a sustainable, plant-based alternative to traditional wastewater treatment. One factor essential to the success of these systems is ensuring their ability to remove pathogens present in wastewater. Wastewater is the primary source of fecal contamination in aquatic ecosystems, containing total and fecal coliforms on the order of 107-109 and 106-108 100 ml-1, respectively. 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 were collected from an ecological treatment system treating liquid manure. A three phase dosing experiment was conducted during the summer and early fall of 2005 to assess the capacity of the treatment system to remove pathogens from liquid manure. 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 96% from influent to effluent, with the majority of the removal (60%) occurring in the first two reactors. Although USEPA discharge requirements for E. coli were not met, the substantial reductions achieved indicate that ecological treatment systems have the potential to successfully remove pathogens from wastewater. The results from this study will be used to guide future ecological treatment system designs, so that even larger pathogen reductions can be achieved.