Meng Fangang, Shi Baoqiang, Yang Fenglin, Zhang Hanmin
Key Laboratory of Industrial Ecology and Environmental Engineering, MOE, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian, 116024, People's Republic of China.
Bioprocess Biosyst Eng. 2007 Sep;30(5):359-67. doi: 10.1007/s00449-007-0132-1. Epub 2007 Jun 14.
In this paper, three identical membrane bioreactors (MBRs) were operated in parallel in order to specify the influence mechanism of hydraulic retention time (HRT) on MBR. The results showed that the removal efficiency of chemical oxygen demand (COD) was stable though it decreased slightly as HRT decreased, but biomass activity and dissolved oxygen (DO) concentration in sludge suspension decreased as HRT decreased. The filamentous bacteria grew easily with decreasing HRT. The extracellular polymeric substances (EPS) concentration and sludge viscosity increased significantly as filamentous bacteria excessively grew. The over growth of filamentous bacteria, the increase of EPS and the decrease of shear stress led to the formation of large and irregular flocs. Furthermore, the mixed liquid suspended solids (MLSS) concentration and sludge viscosity increased significantly as HRT decreased. The results also indicated that sludge viscosity was the predominant factor that affecting hydrodynamic conditions of MBR systems.
本文通过并行运行三个相同的膜生物反应器（MBR），以明确水力停留时间（HRT）对MBR的影响机制。结果表明，化学需氧量（COD）的去除效率虽随HRT的降低略有下降，但仍保持稳定，而污泥悬浮液中的生物量活性和溶解氧（DO）浓度则随HRT的降低而下降。丝状菌易于随HRT的降低而生长。随着丝状菌过度生长，胞外聚合物（EPS）浓度和污泥粘度显著增加。丝状菌的过度生长、EPS的增加以及剪切应力的降低导致形成大而不规则的絮体。此外，混合液悬浮固体（MLSS）浓度和污泥粘度也随HRT的降低而显著增加。结果还表明，污泥粘度是影响MBR系统水力条件的主要因素。
