| Volatile Organic Compounds(VOCs) is another kind of contamination junior to Particles. They do great harm to human health and cause heavy pollution, however, they are hard to be controlled, especially for waste gases borne with low-concentration VOCs. So, an effective control approach is urgent. Biotreatment of air-borne contaminants offer an alternative to conventional air treatment technologies. Because of its advantages, such as simple equipment, low investments & operational spending and no secondary-pollution, it has received increased attention of scholars around the world. This article selected toluene as research object. A bacterial which can highly degrade toluene have been obtained by enriching, screening, acclimatizing the strains in activated sludge. We also research the optimal growing conditions of the bacteria. Finally, kinetics characteristics of strain under no inhibitable conditions was examined. The results were reported as follows: 1. The best environmental conditions for the growth of bacteria are 35 ℃, pH7.0,inoculum quantity 5%, concentration of toluene 40ul by analyzed the result of orthogonal table experiment. The effects order of each parameter is toluene concentration>temperature>pH> inoculate quantity.Under the optimal growing conditions, we found that the degradation toluene rate increased first then dropped with the increase of toluene concentration, and the growth cycle of this bacteria is a little long,its log phase is about 12 hours,and move into steady phase after 16hours by its growth curve 2.It find that specific growth rate will increase initially,then it will decrease in according to the growning of toluene concentration by adding different concentration of toluene.when adding 99.110mg/L of toluene, the degradation property of the strain is good at 20-40℃temperature or at pH=6-7.The number of unit bacteria is not compared with the number of matrix.When inoculate quantity is 0.5%,The degradation speed is the lowest one.When inoculate quantity is over 5%, its effects to toluene degradation is none. 3.The consuming and degradation of toluene have been researched by mass conservation law.And a toluene degradation model under no inhibitive conditions have been deducted by enzyme reaction mechanism. The model expresses as follow:when temperature is at 30℃,pH=7,inoculate quantity is 5%,the range of toluene concentration is at 0-316.5mg/L. "Vm ax"is maximum reaction speed,"kf"is reaction speed constant,"m"is preserving coefficient, Vm ax=0.341 h-1,kf=38.65mg/L,m=0.0876. The formula have represented good coherence and relativity when estimate the degradation of toluene. 4 Based on adsorption-biofilm theory and biochemical reaction kinetics, a noval biotrickling filter model which was used to characterize the degradation of Volatile Organic Compounds has been founded when liquid flux is at 24.4L/h and toluene concentration is between 0 and 800mg/m3 .The toluene concentration distribution on support media have been gotten by this model and finally validated this model.It showed as follow: 110.113(1.155 6.382 )( 121 )0.148( 121 ) 247.3n n nndC C h P Qh Cdh Q P Qh C= ? ? + ? ? ? + ? The coefficient of this model are computed as follow: K a= 1.155, K b= 6.382, K c= 0.148, K f= 247.3. This work implies that it is feasible to use the screening bacteria as the inoculated seed to purify waste gases contaminated by toluene. Through this research, The research on toluene degradation property, statical degradation kinetic and using statical degradation kinetic model on biotrickling filter would not only explain the reaction essence between toluene and Pesudomonas sp but also support references when using this Pesudomonas sp dealing with toluene on biotrickling filter... |
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