Assessment of manganese removal from over 100 groundwater treatment plants
The aim of this study was to make an inventory of water quality and operational parameters which could affect manganese removal through aeration and rapid sand filtration and to establish correlations between these parameters and manganese removal efficiency. The focus of the overview was on manganese removal efficiency in the first aeration-filtration stage of conventional groundwater treatment plants (GWTPs). Data from selected full-scale GWTPs have been collected, and univariate and multivariate statistical analyses were conducted. Multivariate statistics indicated that multiple parameters including NH4+ removal efficiency, iron loading per filter run (FR) and pH of filtrate play a significant role in manganese removal, while other parameters (oxygen concentration in filtrate, filtration rate and empty bed contact time (EBCT)) were found to be of secondary importance. Univariate statistical assessment of the data suggests that very effective manganese removal can be achieved when all of the following conditions are met: NH4+ removal efficiency >85%, pH of filtrate >7.1, iron loading per FR <2.7 kg Fe/m2, oxygen concentration in filtrate >1 mg O2/L, filtration rate <10.5 m/h and EBCT >11.5 min.