Low-temperature effects on the removal of soluble manganese in MnOx(s)-coated media systems

Abstract

The purpose of this study was to investigate the role of low-temperature conditions in potentially impacting soluble Mn2+ removal in MnOx(s)-coated media systems. The study involved an extensive examination of water quality and process data for a ten-year period (2005–2014) from the Harwood's Mill Water Treatment Plant in Newport News, VA. Additionally, laboratory-scale shallow depth column studies were performed employing MnOx(s)-coated media for soluble Mn2+ removal. Data were evaluated for the impacts of low temperature conditions, water pH, soluble Mn2+ concentration, and free chlorine concentration on the ability of MnOx(s)-coated media to promote effective soluble Mn2+ removal. The results show that the uptake of soluble Mn2+ onto MnOx(s)-coated filter media is significantly impacted by water temperatures below 15 °C, with impacts being very substantial under lower temperature (T < 10 °C) conditions. Also, the adverse effects of low temperature on MnOx(s)-coated treatment processes can be at least partially mitigated by an increase in solution pH.