Effect of hydraulic retention time on membrane fouling and biomass characteristics in submerged membrane bioreactors |
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| Authors: | Fangang Meng Baoqiang Shi Fenglin Yang Hanmin Zhang |
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| Institution: | (1) Key Laboratory of Industrial Ecology and Environmental Engineering, MOE, School of Environmental and Biological Science and Technology, Dalian University of Technology, Linggong Road, 2#, Dalian, 116024, People’s Republic of China |
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| Abstract: | 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. |
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| Keywords: | Membrane bioreactor (MBR) Membrane fouling Hydraulic retention time (HRT) Extracellular polymeric substances (EPS) Hydrodynamics |
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