The waste water should have already been pH corrected as it was fed into the Phenolic Waste Tank. Maintaining the pH of the water fed to the OEC between 4.5 and 5.0 is extremely important. The cumene solvent in the OEC cannot remove phenate present in the waste water when the pH is higher than 5.0. The waste water is very corrosive if the pH is less than 4.5.