Research And Parameters Optimization Of Coking Wastewater Advanced Treatment By Nanosopic Fe₃O₄ Fentonlike Process

After the oxidative degradation of contaminants by the conventional Fenton process, a large number of Fe ions exist in the homogeneous will produce a large number of iron mud as the pH increased. A heterogeneous Fenton-technology which based on nano Fe₃O₄ as a catalyst was put forward for this problem. This technology use the magnetic properties of Fe₃O₄ that can be adsorped and separated by applying an external magnetic field in the heterophasic system to reduce the concentration of Fe ions in liquid phase and then reduce the production of iron mud. To study the effectiveness and impact factors of Fenton reagent composed by nano Fe₃O₄ and H₂O₂ in water treatment applications, regard the coking wastewater or the biochemical water in a coking plant in Benxi, Liaoning as the research object, regard A sewage discharge standards as the goal. To make sure that nano Fe₃O₄ class Fenton system can effectively deal with the coking wastewater and stability and compliance, this article mainly search the preparation and modification of catalyst、optimization of reaction conditions in small scale experiments、optimization of operating parameters of the reactor.First of all, the chemical co-precipitation method was used to get 1#catalyst nano Fe₃O₄. The method of surface coating was applicated to make the HA and DMSA were used for surface modification of Fe₃O₄ nanoparticles to get 2#catalyst nano Fe₃O₄-HA and 3#catalyst nano Fe₃O₄-DMSA. The active ingredients of these three kinds of catalyst were Fe₃O₄, which have the diameter of 50¹50nm and better magnetization and demagnetization. The modified 2# and 3#catalyst have better dispersion.Secondly, did a small scale experiments of the coking wastewater effluent by the Fenton-reagent which composed by the three kinds of modified catalyst and H₂O₂. The first step is to explore how the pH of the system、mass concentration of Fe₃O₄、the amount of H₂O₂、reaction time and temperature reflex influence the removal efficiency of COD and volatile phenol by the means of control Variable and get the approximate range of optimum reaction parameters. Then optimize the reaction conditions by the method of multi-factor response surface to obtain the optimal reaction conditions of three kinds of catalyst. Explore the effectiveness of catalyst which can be reused under the optimal reaction conditions. The conclusion shows that among the three catalysts, 2# has the best stability, and the removal efficiency of COD got to 63.32% while Volatile phenol got to 95.09% after 8 times’ usage. 3# has the best initial catalytic efficiency, the removal efficiency of COD got to 75.61% and Volatile phenol got to 99.84% when first used, and it’s turned to be 70.88% and 98.49% after 4 times usage. It can be said that surface modification can improve the stability of the catalyst, make the advantage of reuse of Fenton catalyst system more significant.Finally, design and run the pilot reactor that suitable for class nano Fe₃O₄ Fenton system, use the mode of parallel alternating operation make the water running continuously for the advanced treatment of coking wastewater. Besides, analyze and optimize the hydraulic retention time of reactor during operation、dosing mode of H₂O₂、supplementary dosage of nano Fe₃O₄. Finalize the hydraulic retention time of reactor is 120min、dosing H₂O₂ for 4 times respectively at 20min、40min、60min、80min in the run time. And added 20% of the amount of the initial investment of the the Fe₃O₄ before each repeated reaction. Then there is a 20 days of continuous operation of the reactor. Effluent COD stabilized at 50mg/L or less, volatile phenol basically stable at 0.5mg/L or less, and meet the goals of standard emission.The research of the Fenton reagent composed by nano Fe₃O₄ and H₂O₂ which was used to deal with the coking wastewater, and the optimization of operating parameters through the Fenton system, not only provided a viable processing technique for advanced treatment to meet the standard of coking wastewater, but also explored the feasibility and applicability of nano Fe₃O₄ Fenton system in the advanced treatment and applications of industrial wastewater which are biorefractory、biodegradable、and of low concentration. The research provided a practical guidance for the development of the technology.