Bromate removal during transition from new granular activated carbon (GAC)to biological activated carbon (BAC)

Bromate removal by activated carbon after ozonation in a subject of concern , since bromate is commonly found in the ozonation of bromide-containing wa ter. Though new GAC (granular activated carbon) shows the capacity to reduc e bromate to bromide, n the long-term use of GAC following ozonation, its b romate removal rate apparently decreases during transition from new GAC to BAC (biological activated carbon) after 3 months. Batch bromate reduction e xperiments using new GAC and BAC confirmed new GAC's ability and BAC's inab ility to reduce bromate to bromide. Our experiment also indicated that ion exchangeable bromate adsorption on new GAC was very limited. Based on the r esults of our long-term experiment, the bromate removal rate during the tra nsition from new GAC to BAC was calculated: 1.5 mg BrO3/g carbon when broma te concentration was 50 mu g/l. BAC's inability to reduce bromate makes it necessary to optimize ozonation conditions to minimize the formation of bro mate and other by-products while maintaining target levels trf organic matt er decomposition. (C) 1999 Elsevier Science Ltd. All rights reserved.