Multiphase Mixture Model For Multiphase Transport Characteristics Of Multi-Component Fluid With Biochemical Reaction In Trickling Biofilter

Environmental pollution resulted from the progress of global industrialization has attracted people's great attention. The recovery of low concentration VOC waste gas is valueless and its treatment is very difficult and expensive for traditional physical and chemical treatment technologies. The biological treatment technology of low concentration VOC waste gas has been a hotspot problem in the world,?which has a lot of advantages, such as high purification efficiency, easy operation, low energy consumption, low charge of investment and run, and no secondary pollution etc. At present, many practical equipment have been applied in the control of atmosphere pollution, while there is only a few reports in our country. This paper, author has studied the two phases flow and the degradation characteristic of trickling biofilter: (1) A parallel plat plates theoretical model for purification of low concentration VOC waste gas has been established with simplifying the porous packed material in the trickling biofilter to a parallel plat plates passage covered with biofilm. In the model the liquid film thickness in the passage has been obtained at first using two phase flow theory; then, similar analysis solution of concentration distribution of the pollutant in liquid phase and biofilm has been obtained through mass component equation of pollutant in gas-liquid phases combined with the biochemical kinetic equation of mass transfer in biofilm and dismission of oxygen limited. (2) Based on the parallel plat passage theoretical model, a multiphase mixture model in trickling biofilter with biochemical reaction has been first established applying a multiphase mixture model in porous packed material trickling biofilter with gas-liquid flow, pollutant diffusion and biochemical reaction in biofilm. The predicted value of model theory coincided basically with the experimental result of the waste gas toluene of low concentration in the trickling biofilter. (3) The metabolized heat model in trickling biofilter has been established first combined with a multiphase mixture model in trickling biofilter with biochemical reaction and theory of metabolism.The results of parallel plat plates model and the multiphase mixture model both show that: (1) the purification efficiency of trickling biofilter reduces as the gas or liquid flux increasing. (2) the purification efficiency of trickling biofilter increases as the special surface area of packed material increasing at a constant porosity of packed bed. Furthermore, when the special surface area of packed material is bigger, the effect of it on purification efficiency is less. (3)the purification efficiency of trickling biofilter increases as the height of packed bed increasing. (4) the purification efficiency of trickling biofilter increases as toluene inlet concentration increasing, but the increase in purification efficiency is small. The results of metabolized heat model in trickling biofilter show that: (1) Temperature difference between inlet and outlet of trickling biofilter increases as toluene inlet concentration increasing. (2) Temperature difference between inlet and outlet increases as gas flux increasing. (3) Temperature difference between inlet and outlet reduces as liquid flux increasing. (4) Temperature difference between inlet and outlet increases as the special surface area of packed material increasing at a constant porosity of packed bed. (5) Temperature difference between inlet and outlet reduces as porosity of packed bed increasing at a constant. special surface area of packed material. (6) Temperature difference between inlet and outlet increases as the height of packed bed increasing.