Research On Process Of Nonthermal Plasma Coupled With Bio-Trickling Filter For Chlorine-Containing Benzene-Containing VOCs Treatment

With the continuous development of society and industry,the problem of air pollution has become increasingly prominent.Under the premise of vigorously promoting emission reduction policies and pollution control measures,although the emissions of NO_x,PM_2.5.5 and SO₂ are decreasing year by year,the emission of VOCs is increasing year by year.rise.Among them,the pharmaceutical and chemical industry is one of the huge sources of VOCs,and chlorobenzene was originally used as the bitter acid needed for the production of military explosives.Currently,it is mainly used in the manufacture of phenol,nitrochlorobenzene,aniline and insecticide DDT.An important intermediate in the chemical industry.Traditional VOCs treatment technologies（absorption method,adsorption method,etc.）all have disadvantages such as poor treatment effect,long-term operation,and secondary pollution.The VOCs emissions of different industries have their own specialities,and VOCs emissions for different industries must be“According to local conditions,the right medicine can effectively and stably treat VOCs.The biological treatment of VOCs has a high carbonization rate,low operating cost and no secondary pollution to the atmospheric environment,but because of its toxicity tolerance,it can only treat low concentration VOCs,and the low temperature plasma treatment range is wide,while the carbonization rate is low.However,if the low temperature plasma is used as a pretreatment method,the toxicity of the biological system can be reduced to improve the overall system degradation efficiency.In this study,low temperature plasma coupled bio-trickling technology was used to treat VOCs emissions from the pharmaceutical and chemical industries,and chlorobenzene,a typical organic pollutant in the pharmaceutical and chemical industry,was selected as the treatment target.In the biological drip filtration system research,chlorobenzene was the sole carbon source,and the membrane was successfully run by the rapid sludge removal method after 600 h.After the membrane was successfully completed,the system achieved high-efficiency and stable degradation of chlorobenzene.When the inlet concentration is 1000 mg·m^-3,the degradation effect of the drip filter tower can still exceed 70%.The effect of the membrane hanging on the reactor is observed by scanning electron microscopy.It is found that the film thickness of the lower layer of the reactor is denser than that of the upper layer.The process parameters of the biological drip filter system were studied.It was found that the optimal operating conditions of the biological drip filter system were:chlorobenzene inlet concentration 700 mg·m^-3,residence time 80 s,spray density 10.36 L·m^-3·s^-1,the pH is between 7-8,and the oxygen concentration is 10%.Because xylene is widely used in medicine and other industries as synthetic monomers or solvents,it is one of the characteristic organic pollutants in pharmaceutical and chemical industry.Therefore,xylene is introduced to investigate the interaction between different organic substances in the process of degrading composite VOCs by biological systems.The effect of xylene on the degradation efficiency of chlorobenzene was studied.When the concentration of chlorobenzene and xylene was 1:1,the degradation effect of the biological trickling filter on the mixed exhaust gas reached 87.6%.Through biodegradation macroscopic kinetic analysis,the biological trickling filter When xylene is introduced,the degradation of p-chlorobenzene is inhibited,and on the contrary,the degradation of p-xylene itself is promoted.At the same time,in the chloride ion balance analysis,it was found that chlorobenzene can be completely degraded by the biological system,and the chlorine-containing part enters the circulating liquid and all exist in the form of chloride ions,and with the continuous accumulation of the ion body,the biological system appears to be higher.Tolerance,still functioning properly.High-throughput analysis of the bio-trickling system found that when different substrates were used as microbial carbon sources,the microbial community of the biological system was greatly different,and the abundance analysis of the microbial strains in the bio-trickling system was used to obtain the system.At the completion stage,microorganisms have 12 gates,18 classes,34 orders,53 families,60 genera,and 6 species at different classification levels.When xylene is the sole carbon source,there are different classification levels.9 gates,13 classes,15 orders,17 families,17genera,1 species;when using chlorobenzene and xylene as mixed carbon sources,there are 17 gates and 22 classes at different classification levels.45 orders,71 families,84 genera,43 species;while running to the later stage with chlorobenzene as the sole carbon source,the pH of the drip filter nutrient solution is maintained under acidic conditions,at different classification levels.There are 9 gates,12 classes,20 orders,25 families,29 genera,and 17 species.The degradation characteristics of chlorobenzene and xylene are the genus Chitins and the genus Pleurotus.Finally,this paper studies the process parameters of low temperature plasma and the degradation of chlorobenzene by low temperature plasma-bio-integrated system.The optimal operating conditions for low temperature plasma are:discharge voltage7kV,inlet concentration 700 mg·m^-3,residence time 5.5 s.At this time,the degradation effect of plasma reaches 80%,and the energy efficiency can reach550mg·kWh-1..Moreover,the degradation efficiency and removal load of chlorobenzene in the coupling system are improved compared with the single biological drip filtration system.The inlet concentration is gradually increased from50 mg·m^-33 to 1500 mg·m^-3,and the degradation effect of the coupling system is high.In a single biological system,the degradation efficiency can be increased by 10%to20%under different conditions.