The removal of NOM using dual-coagulant was complex and pH
dependent, and meanwhile, NOM was also affected by dosing
sequence. The dual-coagulants significantly improved NOM removal,
especially CBF–PFC. Both the two dual-coagulants reached
a maximum NOM removal at pH 6. Adsorption and bridging were
believed to be the main removal routes by CBF. In addition, flocs
size and growth rate were also enhanced by CBF. The flocs were
small and grew slowly at neutral and weakly base conditions. The
flocs recovery ability was improved by adding CBF after PAC. The
recovery ability decreased as pH increased and all the flocs showed
a limited recovery capacity. The flocs were more compact at high
pH and the addition of CBF lead to loose structure of flocs due to
its high negative charge.