The Research On Advanced Treatment Of Coking Wastewater By Heterogeneous Photo-fenton

The coking wastewater is a kind of refractory organic wastewater with highconcentration, which is mainly composed of phenol and nitrogen heterocyclic,because it can hardly reach the discharge standards by Secondary biologicaltreatment, so it is necessary to dispose coking wastewater with advanced treatment.It is a hot topic to search cost-effective advanced treatment method to disposecoking wastewater in recent years.Fenton’ reagent is a kind of advanced oxidation technology, it can be used totreat coking wastewater for its advantages of strong oxidation ability and fastreaction rate. However, Fenton’ reagent could have high oxidability only at low pHconditions （pH=3）, a lot of iron sludge were generated after the end of the reaction,so the effluent of water is yellow and result to secondary pollution. Some researchindicted that immobilize the iron ion on the carrier to get the solid catalyst, andestablish the heterogeneous photo-Fenton system H₂O₂and UV, which not only canreaction in wide range of pH, but also the catalyst can be recycled after the reaction.In this paper, copper and iron oxidate catalysts loaded on Al₂O₃/TiO₂wereprepared by precipitation method, the manufacture condition was optimized, theprepared catalyst was characterized. The degradation of p-chlorophenol andquinoline, were two typical pollutants, were used to investigate the influencedfactors of heterogeneous photo-Fenton system, analyzed changes in the compositionof the coking wastewater secondary effluent before and after treatment byheterogeneous photo-Fenton reaction, and the operation stability of heterogeneousphoto-Fenton in advanced treating coking wastewater was investigated.The ratio of copper and iron、 the temperature of calcinations and thecalcinations time on the effect of catalytic activity were investigated, Experimentsshow that the ratio of copper and iron was1:5, the calcinations condition wascalcined at200℃for5h, The prepared catalyst was characterized by SEM, BET,XRD, XPS, the result showed that FeOOH, Fe₂O₃and CuO were the effectivematerials of catalysis. Compared with the carrier, the surface area, total pore volumeand average pore width were decreased.H₂O₂dosage, catalyst dosage, the conceration of solution, the adding modle ofH₂O₂were the important factors of heterogeneous photo-Fenton by treatingp-chlorophenol and quinoline.GC/MS measurement indicated that the mainly organic of secondary effluent ofcoking wastewater were nitrogen heterocyclic, phthalates, polycyclic, and smallamount of phenol and hydrocarbons. After the treatment by heterogeneous photo-Fenton reaction, only some straight-chain alkanes and dibutyl phthalate leftremnanted, it is indicated that the refractory organics of secondary effluent ofcoking wastewater were oxidate to the degradable organics, CO₂and H₂O, the toxityof the water was reduced. The secondary effluent of coking wastewater was treatedby heterogeneous photo-Fenton continuous flow. The effect of H₂O₂dosage, catalystdosage and hydraulic retention time on the treatment were investigated.The heterogeneous photo-Fenton reaction system established in this paper canoperate in a wide range pH, it have advantages of high efficiency and good stability,It has high efficiency for the advanced treatment of coking wastewater which canreach the "iron and steel industry effluent discharge standard" and "integratedwastewater discharge standard level1B", confirmed it is applicable to advancedtreat coking wastewater by heterogeneous photo-Fenton.