Testing monolithic activated carbon adsorbers for in-line removal of organic micropollutants

Abstract

Anthropogenic organic micropollutants (OMP) occur along the whole urban water cycle including drinking water. Various OMP can be efficiently adsorbed onto activated carbon. In the present study a commercial monolithic adsorber (MA), originally developed for gas treatment, was examined for the removal of OMP from drinking water. As a promising advantage, the adsorber can be introduced into existing pipes without causing substantial pressure losses. The MA was first characterized with scanning electron microscopy and energy dispersive X-ray spectroscopy. Weight loss during incineration at 550 °C indicated an activated carbon content of around 25%. Adsorption isotherms were recorded with milled material of the MA to estimate the capacity of the embedded adsorbent. Long-term flow-through experiments with two different flow rates were conducted to estimate the in-line removal efficiency. At low flow rates removals of 60% benzotriazole, 40% carbamazepine and 30% diclofenac were observed initially followed by a linear increase of effluent concentrations. Calculated loadings after 60 days of operation were e.g. 30 μg benzotriazole per g adsorber or 110 μg benzotriazole per g activated carbon as constituent of the adsorber. For specific applications, MA might be useful for the in-line elimination of OMP within drinking water distribution systems.