Biological Oxygen Dosed Activated Carbon (BODAC): an innovative technique for effective fouling prevention

Summary

Biological Oxygen Dosed Activated Carbon (BODAC) is a technology developed to prevent fouling in reverse osmosis systems used for wastewater reclamation at the Ultrapure Water Plant in Emmen, the Netherlands. At the Ultrapure Water Plant, the RO membranes have been in operation for over ten years without replacement and with minimal cleaning. The present thesis examines the BODAC technology by elucidating the mechanisms behind the removal of fouling precursors. A mass balance study of the full-scale BODAC filters revealed that in BODAC filters iron (Fe) and manganese (Mn) are the only fouling precursors that are removed well. With this knowledge, the BODAC filters were replicated at laboratory scale to study the removal routes in depth. Finally, the BODAC filter effluent was spiked with Fe and Mn and passed through a membrane fouling simulator. This experiment revealed that the addition of these two minerals triggered significant membrane fouling. This finding shows that the effective fouling prevention by BODAC filters is indeed related to the removal of Fe and Mn.