Therefore, sorption of PCBs onto sludge was the most likely removal mechanism in the primary and biochemical treatment stages.
In highdensity clarifier stage, PCBs concentrations in effluent and
sludge samples decreased more significantly than the ones in the aerobic bioprocess stage owing to the oxidation (although
no evidence is available in the literature of ferrate reaction
with PCBs) or the coagulation by ferrate, because ferrate
at pH < 7 generates Fe(III) ions with excellent flocculation
capability and Fe(OH)3 that is a good adsorben