EDTA in dairy wastewater and removal efficiency - A case study

Abstract

EDTA is the most widely used chelating agent for removal of undesirable cations in many industrial applications such as the dairy industry. It is generally considered to be non-biodegradable by conventional wastewater treatment, thereby potentially producing an environmental health risk. Under suitable conditions, however, EDTA has been reported to be effectively degraded by micro organisms during wastewater treatment. This study examined degradation of EDTA from a dairy wastewater treatment process in New Zealand operated at pH 8.0-8.2, with a three-week sludge retention time. An HPLC-UV analytical method was used to measure EDTA. A wide range of EDTA concentrations (93 to 5194 μg/L) was measured in the influent entering the wastewater treatment plant, while concentrations of 72-260 μg/L were measured in dairy effluent discharged into the local stream. About 93% of EDTA was degraded by the wastewater treatment. This study demonstrates that the wastewater treatment process at a dairy plant in New Zealand was very effective in removing EDTA.