Combined Processes Of Photoelectric Fenton And Three-dimensional Electrode For The Treatment Of Coking Wastewater

In recent years,with the continuous growth of steel output,the scale of coking in China is increasing day by day,and the coking wastewater produced in the coking process is also increasing gradually.Coking wastewater is a high concentration industrial wastewater which is difficult to be biodegradable.Its composition is complex,its biodegradability is poor,its toxicity is high,the treatment effect of traditional biochemical process is not ideal,and the effluent quality is not up to standard.Therefore,developing new treatment technology to treat coking wastewater efficiently has become the focus of research in recent years.The advanced oxidation method has gained more and more attention and research in the field of treating high-concentration organic wastewater because of its strong oxidation capability,fast reaction speed,and no secondary pollution.Electric Fenton method is a kind of advanced oxidation method,which can handle organic wastewater simply and quickly.However,the common two-dimensional electrode reactor has the problems of low reaction efficiency and incomplete degradation of organic materials.The three-dimensional electrode method can solve these problems.At the same time,the photocatalytic oxidation method is also a new technology with a wide range of application prospects in the field of wastewater treatment.The photocatalytic oxidation method has the characteristics of strong oxidizing ability,easy control of reaction conditions,no secondary pollution,etc.,so it has become a research in recent years.Therefore,the Fenton reaction is placed in a three-dimensional electrode reactor and combined with photocatalytic oxidation to treat coking wastewater.The application in the concept of disposal waste with waste,solid waste coke powder was used as the particle electrode to construct three-dimensional electrode technology for the pretreatment of coking wastewater combined with photoelectric Fenton-like process,improving its biodegradability.Firstly,in order to improve the mass transfer performance of the coke particle electrode,the surface of the metal powder was impregnated and modified to select the metal element with the best catalytic effect.The modified coke powder was characterized by X ray diffraction,Fourier infrared spectroscopy and Environmental scanning electron microscope.Secondly,the effects of electrolysis voltage,electrolysis time,particle electrode dosage,initial pH,electrode spacing,TiO₂ dosage and other factors on the treatment of coking wastewater were analyzed.The COD_Crr value before and after the experiment was measured using potassium dichromate method.The best application conditions were compared;COD_Crr removal efficiency of two-dimensional photoelectric Fenton method,three-dimensional photoelectric Fenton method coking wastewater was compared.Experimental results show:The phase of Fe₂O₃ appears in the XRD spectrum.A new Fe-O stretching vibration absorption peak appears in the IR spectrum,indicating that Fe₂O₃ is successfully supported on the coke powder.The SEM image shows that the pores of the modified coke particle have increased.It facilitates the mass transfer inside the electrode.Photoelectric Fenton synergetic three-dimensional electrode treatment of coking wastewater is significantly better than two-dimensional electrode method and three-dimensional electrode method.The optimal application conditions obtained by the experiment are:electrolysis voltage is 15 V,electrolysis time is 1.5 h,particle electrode dosage is 30 g·L^-1,initial pH is 3.0,plate spacing is 5 cm,TiO₂ dosing The amount is 6.0 g·L^-1.Under the optimal application conditions,COD_Crr removal rate of wastewater reached 79.8%,BOD₅/COD_Crr value increased from 0.08 to 0.32,and biodegradability increased significantly,which is favorable for follow-up biological treatment.On the one hand,it achieves the purpose of waste treatment and waste treatment,achieves the goal of recycling coking wastewater and the internal recycling of coke powder,and on the other hand improves the treatment effect of three-dimensional electrodes and reduces operating costs.