生物膜填料床内含有生化反应的多相传输模型

Model of multiphase transport behavior in bio-filter for waste gas treatment

废气处理生物膜滴滤塔的多孔填料床内是带有气液两相流动、有机污染物扩散、生物膜内生化反应的复杂生化反应体系.在平行平板理论模型基础上,建立了生物膜多孔填料床内含生化反应的多元多相流动及传输特性的多相混合模型,获得了废气处理生物膜滴滤塔净化效率的理论计算方法.模型的理论预测值与生物膜滴滤塔净化低浓度甲苯废气的实验结果基本吻合.

In the trickling bio-filter for waste gas treatment, there exists a series of complicated transport phenomena such as gas and liquid two-phase flow, pollutant transport, and biodegradation reaction in packed bed with bio-film. A multiphase mixture model was established for studying the transport behavior in the porous packed bed with multiphase flow of multi-component fluid of trickling bio-filter for gas waste treatment. The two-phase multi-component fluids were treated as a compound fluid in this model. The momentum equation and mass component equation were given for the compound fluid based on the transport theory for multiphase flow in porous medium. The source term in the mass component equation was derived from a pore-level model to reflect the relationship of the pollutant biodegrading rate with local pollutant concentration, liquid saturation, structure of packed bed, and biochemical reaction kinetics in trickling bio-filter. To take account of the effect of packed bed clogging on the purification efficiency of trickling bio-filter with smaller particles, a bio-film coverage rate was introduced into the calculation of effective mass transfer area. The purification efficiency of trickling bio-filter for low concentration toluene waste gas was predicted theoretically from the present model for packed bed with 25 mm particles or 8 mm particles in co-current flow or reflux flow, respectively. As compared with experimental results, the discrepancy between theoretically predicted values and experimental data was within ±21.9%.