Removal of Cs+ and Co2+ from Domestic Wastewater by Adsorbent Addition

The removal of radiological agents from a wastewater treatment plant that entered via the detonation of a radiological dispersive device (RDD) was investigated. Cobalt and cesium have been the focus of simulated RDD events and therefore were chosen as the radionuclides to be studied. The goal of the study was to determine the efficacy of using commercially available adsorbents to remove Cs and Co from wastewater. Based on adsorption experiments two adsorbents were chosen for further study: sorbent ATS was selected for Co and IONSIV (UOP, Des Plaines, Ill.) IE-911 was chosen for Cs. Both ATS–Co and IE911–Cs were modeled using the Langmuir isotherm. Co removal by ATS increased with increasing pH. Cs adsorption by IE-911 was not a function of pH directly but decreased with increasing pH due to the increased removal of other cations (e.g., calcium). Removals of Co and to a lesser extent Cs were not significantly affected by the presence of wastewater solids and dissolved organics. The level of mixing did not adversely affect ATS/Co or IE-911/Cs removal kinetics. ATS’s Co removal capacity was constant with temperature, whereas IE-911–Cs’s capacity decreased with decreasing temperature. Both ATS–Co and IE911–Cs removal kinetics decreased with temperature.