Desalination 199 (2006) 405–407 Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. Removal of heavy metals from drinking water supplies through the ion exchange membrane bioreactor Adrian Oehmen*, Rui Viegas, Svetlozar Velizarov, Maria A. M. Reis, João G. Crespo CQFB/REQUIMTE, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal email: adriano@dq.fct.unl.pt Received 19 October 2005; accepted 6 March 2006 Abstract Arsenic (As) and mercury (Hg) are two highly toxic heavy metals that must be removed to very low levels in drinking water supplies. A novel treatment method for the removal of both compounds is the ion exchange membrane bioreactor (IEMB) process, which incorporates pollutant transport through an ion exchange membrane by Donnan dialysis, with biological removal of the pollutant. As detailed in this study, the IEMB process has a high potential for use in drinking water treatment systems, and offers numerous advantages over currently implemented processes, such as minimising the risk of secondary pollution of the drinking water. Keywords: Anion exchange membrane (AEM); Cation exchange membrane (CEM); Arsenate (H 2 AsO 4 – ); Arsenite (H 2 AsO 3 – ); Ionic mercury (Hg 2+ ); Biological removal 1. Introduction Heavy metals have been found in poten- tially harmful concentrations in numerous drinking water systems due to natural or indus- trial pollution sources. Two of the most toxic heavy metals are arsenic (As) and mercury (Hg), and thus each compound must be removed to very low levels in order to prevent health problems. The maximum concentrations of arsenic and mercury recommended by the World Health Organization are 10 ppb and 1 ppb, respectively. The main limitations of existing treatment technologies are secondary contamination by microbial cells, nutrients, and metabolic by-products in biological processes; difficul- ties in disposing the brine solution from pres- sure driven membrane processes; high energy demands in distillation processes; competition for adsorption sites in ion-exchange systems by other ions that are usually present in much higher concentrations; and the undesirable addition of chemicals, as well as difficulties in *Corresponding author. doi:10.1016/j.desal.2006.03.091