MBR运行初期对基因工程菌的截留特性研究

Interception Characteristics of MBR for Genetically Engineered Microorganism (GEM) at the Beginning of Operation

摘要:

在膜-生物反应器(MBR)中实施基因工程菌生物强化时, 运行初期基因工程菌流失是生态风险评价的重要内容。在一体式微滤膜-生物反应器中, 考察了运行初期不同运行条件对基因工程菌流失密度和截留效率的影响, 并对截留特性进行了探讨。结果表明, 膜-生物反应器运行初期, 不同运行条件对基因工程菌的截留效率影响不同：污泥浓度增加, 截留效率提高; 提高膜通量和曝气量, 截留效率降低。基因工程菌接种密度为1.0×1010 CFU/mL时, 不同运行条件下的流失密度为1.0×102 CFU/mL~2.5×102 CFU/mL, 最大截留效率大于8 lg。膜-生物反应器运行初期, 膜组件截留、污泥吸附以及对悬浮细胞迁移阻碍是影响截留效率的主要因素, 一定条件下其截留效率贡献率分别为82.3%、14.9%和2.8%。膜-生物反应器稳定运行过程中形成凝胶层, 可以提高截留效率。一定条件下, 膜组件、污泥和凝胶层对基因工程菌的截留贡献率分别为75.3%、10.7%和14.0%。

Abstract:

The leakage of genetically engineered microorganism (GEM) at the beginning of operation was the important content for ecological risk assessment when GEM was inoculated in a membrane bioreactor (MBR) for bioaugmentation. The effects of different operating conditions on leaking density and intercepting efficiency of GEM were investigated in a submerged microfiltration MBR at the beginning of operation. The interception characteristics were also discussed. The results showed that different operating conditions had different influences on intercepting efficiency: higher sludge concentration was profit for interception, while higher aeration intensity and flux had opposite effects on interception. When the inoculated density of GEM was 1.0×1010 CFU/mL, the leaking densities varied from 1.0×102 CFU/mL to 2.5×102 CFU/mL under different operating conditions at the beginning of operation and the maximum intercepting efficiency could be higher than 8 lg. The main factors determining intercepting efficiency at the beginning of operation were membrane module interception, sludge adsorption as well as suspended GEM transfer inhibition and their contribution shares under certain conditions were 82.3%, 14.9% and 2.8%, respectively. Gel layer formation during MBR stable operation was helpful to increase intercepting efficiency. The contribution shares for GEM interception of membrane module, sludge and gel layer were 75.3%, 10.7% and 14.0%, respectively, under certain conditions.