Study On The Advanced Treatment Of Coking Wastewater By Fenton Reagent Oxidation Process

Components in coking wastewater are very complex, including many pollutants,such as hydroxybenzene, cyanogen, quinoline, pyridine, ammonia, and so on. What’s more, due the high concentration, toxicity and stabilization of thus pollutants, coking wastewater become a kind of typical organic wastewater that difficult to degrade. The content of COD in the effluent after treatment by traditional biochemical procedures is difficult to meet the increasingly stringent environmental standards. In recent years,as shortage of water resources and pollution of environment are becoming more and more serious, andvanced treatment has been increasing urgent for industrial wastewater from conventional biochemical treatment.The study mainly aims at treatments of the second pond water of a coal tar group of anyang city in which the concentration of COD and ammonia nitrogen is higher than nation discharge standard after biochemical treatment, Fenton reagent oxidation menthod is proposed for advanced treatment on the foundation of comprehensive investigation advanced treatment methods for coking wastewater, viewing to achieve recycling and zero emissions.In the Fenton oxidation treatment experiments, through orthogonal experiments and singel-factor test, we can know that : the main factor affecting the Fenton oxidation treatment effect of COD and their primary and secondary relationship is :the dosage of H₂O₂>the dosage of Fe²⁺>initial p H>reaction time; the main factor affecting the Fenton oxidation treatment effect of ammonia nitrogen and their primary and secondary relationship is :the dosage of Fe²⁺>reaction time>initial p H>the dosage of H₂O₂. The optimuln operating conditions for Fenton oxidation is that:the dosage of H₂O₂ is 333mg/L, the dosage of Fe²⁺ is 200mg/L, initial p H is 3, reaction time is 60 min. Under these conditions, the removal rate of the wastewater’s CODcr and ammonia nitrogen is about 77.81%�'� 51.33%, which can be removed to 57.72mg/L�'� 2.92mg/L respectively, reaching the requirements of the urban sewage recycling industrial water quality（GB/T19923-2005）.COD from the coking wastewater oxidation degradation by Fenton’s reagent was kinetically investigated in this study. Using differentiation, it is obtained that the overall reaction order is 2.0017,and the reaction order of COD、H₂O₂ and Fe²⁺are0.4940、0.5685 and 0.9392 respectively. And the kinetic equation are as follows:It is obvious that the reaction order of H₂O₂（0.5685） is higher than that of Fe²⁺（0.4961）, which indicates that the effect of inital H₂O₂ concentration is greater than that of Fe²⁺ on the oxidation degradation of COD by fenton process. The lower activation energy of 3.86 k J/mol shows that Fenton reaction can be initiated easily.GC-MS analysises of the coking wastewater showed that organic compounds was greatly reduced, phenolic,chain hydrocarbon,aldehydes and esters were completely removed,most compounds were absolutely dislodged or degraded into small molecular organic acids and Phthalic acid dibutyl. The possible interpretation of the way can be concluded through the research and analysis.