TBAA reduction in reactors simulating distribution system pipes

To investigate the potential role of abiotic reduction in the loss of disinfection by-products in distribution systems, the degradation of tribromoacetic acid (TBAA) in pipe reactors made of new and previously in-service iron pipe was studied. TBAA was degraded in all of the reactors, with dibromoacetic acid, bromoacetic acid, and bromide as the observed products. The observation of these dehalogenation products under oxic conditions-in which oxygen would be preferred over TBAA as a terminal electron acceptor for biological processes-indicates that abiotic reduction by iron minerals at the pipe wall is responsible for the observed denomination reactions. The iron oxides formed in the pipes comprised goethite, lepidocroc'ite, and magnetite. Results suggest that abiotic reduction of highly reactive disinfection by-products at the pipe wall is potentially an important loss process in distribution systems.