Study On The Treatment Of Simulated Exhaust Gas Of Toluene And Dichloromethane By Biological Trickling Filter

In recent years,the rapid development of the petrochemical industry has attracted great attention from the society.While promoting economic development,it also poses a serious threat to the air quality of our country.Especially,Volatile Organic Compounds（VOCs）have been highly valued for their carcinogenic,teratogenic and mutagenic hazards to human body.Among the common treatment technologies of VOCs,biological method is a better economic treatment technology for low concentration VOCs because of its simple process,simple operation,low operating cost and no secondary pollution.In this study,the biotrickling filter process was used to degrade the mixed simulated exhaust gas of toluene and dichloromethane.Start the experimental device under the conditions of inlet concentration of 400 mg/m³,water bath temperature of30^oC,spraying amount of circulating nutrient solution of 4 L/h,inlet flow rate of 0.15m³/h,gas-liquid ratio of 40 and residence time of 160 s.After the removal efficiency is stable,the gas concentration increases to 1000mg/m³,and other conditions remain unchanged.The effect of concentration change on the degradation efficiency is investigated.The Solubilization Effects of four surfactants on toluene and dichloromethane,and the effects of four surfactants and four metal ions on microbial growth were investigated.The results showed that Tween-20 had better solubilization effect on toluene and dichloromethane in solubilization experiment,and Tween-20and Ca²⁺had the most obvious effect on microbial growth in the effect experiment of microbial growth,with maximum absorbance values of 0.311 and 0.205,respectively.Different concentrations of Tween-20 were added to the biotrickling filter to investigate the effect of Tween-20 on the removal of mixed simulated waste gas.When 50 mg/L Tween-20 was added,the removal efficiency of biotrickling filter for mixed simulated waste gas was the highest,which was 81.82%,and the removal capacity was 20.07 g/（m³·h）.On this basis,the effect of Ca²⁺concentration on removal efficiency was investigated.The results showed that on the basis of adding50 mg/L Tween-20 and 35 mg/L Ca²⁺,the removal efficiency was 97.61%and the removal capacity was 23 g/（m³·h）.In order to combine with the actual production process,the effects of organic load and residence time on the removal efficiency of trickling filter were investigated.The results show that the removal efficiency of mixed waste gas by trickling biofilter decreases with the increase of organic load,but the removal capacity of toluene and dichloromethane increases to a certain extent.The removal efficiency decreases with the decrease of residence time when residence time is 240s and 160s.The addition of Tween-20 and Ca²⁺enhanced the performance of the biotrickling filter,enabling it to quickly recover its activity and maintain long-term stable operation.