Start-Up Performance Evaluation of Submerged Membrane Bioreactors Using Conventional Activated Sludge Process and Modified Luzack-Ettinger Process

Abstract

The rising trend of converting conventional activated sludge processes to membrane bioreactor (MBR) processes for water reuse requires studying the start-up performance of bioreactors, during which mixed liquid suspended solids concentrations increase significantly. One conventional activated sludge MBR (CAS-MBR) and one modified Luzack-Ettinger (MLE) type MBR (MLE-MBR) with mixed liquor recirculation were evaluated for their performance on organic and nutrient removal, membrane fouling, biomass characteristics, and bacterial activities during the start-up period. The two bench-scale MBRs had identical reactor volume (7.2 L) and were operated under continuous flow conditions with no sludge wasting during the start-up operation. It took approximately 130 days for the MBR biomass concentrations to increase from initial 2,500 mg biomass