Numerical simulation of scaling-up for AEC-MBRs regarding membrane module configurations and cyclic aeration modes

Abstract

The airlift external circulation membrane bioreactors (AEC-MBRs) have been attracting attentions due to their capabilities of nutrient removal with lower energy demand and smaller footprint. The gap between laboratory study and full-scale AEC-MBRs regarding hydrodynamics needs to be addressed. In this study, impacts of seven design variables and cyclic aeration modes on hydrodynamics were studied for the scale-up of AEC-MBRs with computational fluid dynamics modelling. The results demonstrated that shear stress on membranes was 14.7% higher in full-scale MBR with only 15% of SAD of lab-scale MBR while it showed an overall higher sensitivity to the design variables in lab-scale MBRs. Cyclic aeration modes created a sinusoidal pattern of shear stress and generated more fluctuations and were expected to reduce more irreversible fouling. When a shifting frequency of 5s/5s was applied in AEC-MBR, 50% of aeration energy was reduced and yield water with good quality was harvested.

Aeration pipe design for free bubbling hydrodynamic optimization of flat sheet MBRs

“…Membrane fouling has seriously inhibited its extensive application [2][3][4]. At present, aeration is the normally used method to ameliorate foiling [5,6]. However, the low efficiency of air utilization and uneven bubble flow from traditional aeration devices has limited the hydrodynamic effect of bubbling on fouling control, particularly at full-scale [7].…”