Abstract: Aeration circulating bioreactor is one kind of bioreactor with aerating riser located at letdown area for wastewater treatment,and there often is packing in the down area as carriers for growth of microbes.Hydrodynamics and mass transfer characteristics of the bioreactor were studied by changing flux(V_l)and velocity(U_ld)of circulation liquid,and variance of residence time distribution function(σ_θ²).There is a better power law correlation between V_l and gas flow(V_g)whether there is packing or no packing in the down area and whatever various sectional area ratios of the aerated riser and the bioreactor(A_r/A_re).With increase of A_r/A_re,V_l and U_ld go up first and then down and the extreme values appear at A_r/A_re 0.11.Compared with the packing-free bioreactor,for packing bioreactor both V_l and U_ld decrease but value of σ_θ² increases,so liquid mass transfer is improved.For bioreactor with parking at the conditions of A_r/A_re 0.11,liquid influent 0.1 m³·h^-1and the gas flow 0.5-3.1 m³·h^-1,the flux of circulation liquid flow is 9—28 times larger than that of liquid influent i.e.from 0.9 m³·h^-1 to 2.8 m³·h^-1 and σ_θ² larger than 0.9.Therefore,the aeration circulating bioreactor is of higher liquid mass transfer such as liquid mixing and diluting,and can be directly used for treatment of high concentration wastewater.

Key words: circulating aerated bioreactor, hydrodynamics, liquid mass transfer

摘要： 循环曝气生物反应器是一种具有曝气筒的用于废水处理的生物反应器,曝气筒外为下降区,常常填充填料作为微生物生长的载体。从循环液量(V_l)、环流液速(U_ld)以及停留时间分布函数的量纲1方差(σ_θ²)等方面研究了循环曝气生物反应器的流体力学性能和传质特性。研究表明,在下降区内有或无填料以及不同曝气筒截面积与反应器截面积比值(A_r/A_re)的情况下,循环曝气生物反应器内的循环液量与气体流量之间均符合幂函数关系,A_r/A_re对循环液量或循环液速的影响是先增后减,极值点为0.11。下降区放置填料降低了循环液量、循环液速,但提高了σ_θ²,改善了液相传质性能。当A_r/A_re为0.11时,在液体进料为0.1 m³·h^-1、气体流为量0.5~3.1 m³·h^-1的情况下,循环曝气生物反应器内的液相循环量是液相进料的9~28倍、σ_θ²为0.9以上,循环曝气生物反应器具有较好的液相混合和稀释能力,可直接处理高浓度废水。

关键词: 循环曝气生物反应器, 流体力学特性, 液相传质特性