Synergistic and antagonistic effects in the photoelectrocatalytic disinfection of water with TiO2 supported on activated carbon as a bipolar electrode in a novel 3D photoelectrochemical reactor

•First study on the application of 3D bipolar electrodes to bacterial inactivation.•GAC-TiO2 composite provides a good photocatalytic inactivation rate.•Bipolar electrode does not improve electrochemical disinfection.•Electrolysis generates chlorine and photocatalysis generates hydroxyl radicals.•Photoelectrocatalytic combination is antagonistic for bacterial inactivation.