Study On N-Hexane Waste Gas Purfication By Collaboration Of Microorganism And Plants

N-hexane was used as solvents in industrial production widely, while the health problems caused by its improper operation to workers cannot be ignored in recent years. This paper adopted microbial packing tower planted with ryegrass to process simulative n-hexane waste gas and studied the influence to bacteria’s distribution and enzymatic activity of ryegrass. The results showed that at same filling height the introduction of ryegrass increased the number of bacteria, fungi, actinomycete significantly compared ryegrass-microbial packed tower(A) with microbial packed tower(B).The number of bacteria, fungi in packing tower A presented rule of decrease in rhizosphere region-transition region-non-rhizosphere region, while this rule was not obvious in actinomycetes. The activities of catalase and dehydrogenase in packing tower A were higher compared with packing tower B, and the activity of catalase presented rule of decrease in rhizosphere region-transition region-non-rhizosphere region.The paper studied reaction conditions of n-hexane in biological filtration purification and researched the influence of the inlet n-hexane concentration, filling height, temperature, light on n-hexane removal efficiency specifically. The results indicated that for ryegrass-microbial packed tower and microbial packed tower, the n-hexane purification rate increased with the inlet n-hexane concentration rising, while the efficiency declined with the inlet n-hexane concentration rising. The n-hexane purification rate declined with the increase of the filling height, while the efficiency increased with the increase of the filling height. When the inlet n-hexane mass concentration was 0～500 mg-m"3 and the filling height was 600 mm, the outlet n-hexane mass concentration was 0～46 mg·m-3 which was all lower than 100 mg·m-3 ruled by GBZ 2.1-2007 《The allowable concentration of toxics in workplace air)) The n-hexane purification rate and efficiency increased when temperature rising and the optimum temperature for ryegrass-microbial packed tower was 25℃. The n-hexane purification rate of ryegrass-microbial packed tower increased with the light intensity enhancement, it reached the maximum with the light intensity was 240μmol·m-2·s-1, while the n-hexane purification rate of microbial packed tower varied inconspicuously. The purification effect of ryegrass-microbial packed tower was superior to microbial packed tower at identical conditions.Through the simulation in dynamics process of biological purification hexane, the results indicated that the n-hexane concentration calculated through the equation fitted with the experimental data exactly. This equation could guide the design of n-hexane biofiltration process.Compared purification rates of both packing tower after removing ryegrass from tower A for a month, the results showed that the difference of n-hexane purification rate between packed tower A and B gradually shrink and converged with the increase of filling height.