Boiler Chemical Cleaning Wastewater

I have a project that requires to treat the boiler chemical cleaning wastewater which is high in COD. The specification requests the oxidative process to be used to remove the COD. The client doesn't provide an additional basin to store the boiler chemical cleaning wastewater. It will be treated together with general wastewater from the power plant. Can anyone help and advise what kind of oxidative process/chemical can be used in order to reduce the COD?