Estrone Removal In Treatment Systems Designed For Nitrogen Removal

Abstract

New rules regarding total nitrogen levels in wastewater treatment plant (WWTP) effluents may result in widespread implementation of total nitrogen removal technologies. Conventional nitrification systems do not remove total nitrogen, instead only oxidizing ammonium to nitrate. Conventional nitrification, however, does result in estrogen degradation. One estrogen naturally secreted by humans, estrone (E1), is a major contributor to the estrogenicity of WWTP effluent. The objective of this work was to provide guidance on the impact that changes in wastewater treatment practices could have on E1 removal by comparing E1 degradation in conventional nitrification systems with that in a range of treatment technologies designed to remove total nitrogen from wastewater. E1 removal was assessed in the following lab scale systems: conventional treatment at room temperature, e.g. 21±2 °C, (96% mean E1 removal), conventional treatment at 15 °C (99% mean E1 removal), Modified Ludzack-Ettinger treatment (96% mean E1 removal), aerobic granular sludge treatment (14% mean E1 removal), a sequencing semi-batch treatment (97% mean E1 removal) and an anaerobic ammonium oxidation (ANAMMOX) treatment (99.8% mean E1 removal). This work demonstrated that the choice of nitrogen removal technology used by a treatment plant could have a significant impact on the estrogenicity of WWTP effluent. Of particular note was that granular aerobic sludge treatment was contraindicated for applications where the estrogenicity of the effluent is important to consider, whereas the energy efficient ANAMMOX technology may be a good option for total nitrogen removal in similar situations.