Study On Treatment Of Simulated Toluene Waste Gas By Biological Drip Filtration System

Volatile organic gas emissions are one of the major causes of environmental pollution and pose a serious threat to human health issues.Among them,toluene is a typical gas in volatile organic waste gas,which is produced in many industries during production and transportation,and has problems such as volatilization,large gas volume and low concentration,which is difficult to be treated.Therefore,it is important to develop a method for efficiently treating toluene waste gas.In this study,the biological drip filtration system was designed,the polyurethane sponge was used as the filler,the simulated toluene waste gas was used as the target gas,and the activated sludge was used as the bacterial source to directly hang the membrane.The blank system,the start-up membrane and the stable operation at room temperature were investigated respectively.The effects of toluene intake concentration,intake air volume and nutrient solution spray rate on toluene removal efficiency;biofilm morphology and structure at different stages were tested by scanning electron microscopy and high-throughput technology;detection of purified products,analysis of toluene Degree of degradation and causes;Finally,optimization of test conditions was carried out by response surface analysis.Under the condition of cost saving,a biological drip filtration system with efficient and stable operation is obtained,in order to provide certain theoretical support for the subsequent research work.Research indicates:(1)Test run of empty tower without filler,the difference of toluene inlet and outlet concentration is less than 3%,the system has good air tightness;the adsorption efficiency of toluene under various factors of blank system is between 3%and 5%,which is used for subsequent systems.So,the impact is negligible.(2)Bio-trickling system is under the conditions of toluene intake of 15 L/min,intake concentration of 100~300 mg/m~3 and nutrient solution spray rate of 60 ml/min,the activated sludge filming time is less than 30 days.When the inlet concentration is increased to 500mg/m~3,the toluene removal efficiency is still above 90%.(3)The results of stable operation of the system show that with the increase of intake air volume and intake air concentration,the removal efficiency decreases slightly;the intake air amount is changed to 5~25 L/min,and the intake air concentration is 100~1000 mg/m~3.The removal efficiency is still above 85%;the spraying rate of the nutrient solution is changed to10~100 ml/min,and the toluene removal efficiency is stable at about 95%.The results of the response surface optimization analysis are basically consistent.The three factors of the intake air amount,the intake air concentration and the nutrient solution spray rate and the corresponding interactions have little effect on the degradation efficiency of toluene under the experimental and predicted conditions.(4)With the increase of membrane time,the shape of biofilm is also changing constantly;after successful membrane hanging,the microbial colonies during high-efficiency operation are analyzed.The results show that the Proteobacteria are the dominant bacteria in this experiment.(5)The complete purification product of toluene is carbon dioxide and water.The analysis of the intermediate product by gas chromatography-mass spectrometer indicates that the process by-products include hydrocarbons,alkynes and aromatic hydrocarbons,in addition to toluene which is not degraded.