Study On Synergistic Treatment Of Chemical Wastewater Containing Benzene And Styrene By Fenton Oxidation And D-A~2/O

In recent years,with the rapid development of China’s economy and the rapid rise of the chemical industry,the environmental pollution problem is becoming more and more serious.As important raw materials and organic solvents,benzene and styrene are widely used in the chemical industry,causing serious pollution to the water.This topic simulates the wastewater containing benzene and styrene produced by a tank car cleaning plant.The wastewater has the characteristics of high toxicity,difficult degradation and poor biodegradability.It is difficult to completely remove it by a single treatment method.The study used a combination of Fenton oxidation and D-A²/O and A²/O processes as the main treatment method.Through the small-scale experiment,the optimal reaction conditions and combined process are studied and determined to improve the treated effluent quality.In the Fenton oxidation stage,the optimum reaction conditions were determined.When V（H₂O₂）=2m L,n(Fe²⁺):n（H₂O₂）=1:9,p H=3 and reaction time T=2h,the removal rate of benzene and styrene can reach more than 90%,and the removal rate of TOC can reach more than 85%.Most of the intermediate products degraded by this method are small molecules of organic matter,such as alkanes,acids,aldehydes,etc.,and some of them are directly mineralized into inorganic substances such as H₂O and CO₂.Determine the best operating conditions in the D-A²/O process and A²/O process stages.Fenton oxidation effluent is mixed with simulated domestic sewage.The mixed wastewater mainly contains ammonia nitrogen,benzene,styrene and intermediate products produced by Fenton oxidation.Changing different hydraulic retention time（HRT）,it is found that when HRT=36h,the treatment effect of D-A²/O process and A²/O process is the best.At this time,the removal rates of benzene,styrene,COD and ammonia nitrogen by D-A²/O process are about 97%,94%,92%and 97%respectively;The removal rates of benzene,styrene,COD and ammonia nitrogen by A²/O process are about 94%,90%,91%and 87%respectively.When HRT=36h,comparing the structure and microbial content of sludge in D-A²/O process and A²/O process,it is found that the relationship between the tightness of sludge structure and microbial content in the two processes is:2#each tank in D-A²/O process>A²/O process>1#each tank in D-A²/O process.The research shows that the collaborative treatment of wastewater containing benzene and styrene by Fenton oxidation and D-A²/O has reasonable structure,good method and feasible technology,which provides experience and technical support for the treatment of such wastewater.