Method and system for treating maleic anhydride production comprehensive wastewater

The treatment method comprises the following steps: sequentially carrying out oil separation, coagulating sedimentation and air floatation treatment on the maleic anhydride production comprehensive wastewater under an acidic condition to obtain pretreated wastewater containing DBP (Dibutyl Phthalate); feeding the pretreated wastewater into a photo-Fenton catalytic oxidation reactor, adding a ferrous sulfate solution, uniformly stirring, turning on an ultraviolet lamp tube, and then adding a hydrogen peroxide solution to carry out photo-Fenton catalytic oxidation reaction; after the illumination reaction is finished, adjusting the pH value of the solution to be alkaline, and adding PAM for flocculation to obtain pre-oxidized supernate; pre-oxidized supernate enters the IC anaerobic reactor, effluent of the IC anaerobic reactor enters the accurate aeration low-oxygen AO reactor, a low-oxygen AO biochemical reaction is carried out, and the effluent meets the discharge requirement. Through photo-Fenton catalytic