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.