A comparison study on membrane fouling in a sponge-submerged membrane bioreactor and a conventional membrane bioreactor

Abstract

h i g h l i g h t sLess SMP and bound EPS in activated sludge in the SSMBR induced lower R C and R P . Lower biomass growth and sludge viscosity contributed to lower R C in the SSMBR. Larger sludge flocs, higher zeta potential and RH led to lower R T in the SSMBR. Sponge could prevent pore blocking and cake layer formation. Sponge addition could reduce SMP C and EPS C through adsorption and biodegradation. This study compared membrane fouling in a sponge-submerged membrane bioreactor (SSMBR) and a conventional membrane bioreactor (CMBR) based on sludge properties when treating synthetic domestic wastewater. In the CMBR, soluble microbial products (SMP) in activated sludge were a major contributor for initial membrane fouling and presented higher concentration in membrane cake layer. Afterwards, membrane fouling was mainly governed by bound extracellular polymeric substances (EPS) in activated sludge, containing lower proteins but significantly higher polysaccharides. Sponge addition could prevent cake formation on membrane surface and pore blocking inside membrane, thereby alleviating membrane fouling. The SSMBR exhibited not only less growth of the biomass and filamentous bacteria, but also lower cake layer and pore blocking resistance due to lower bound EPS concentrations in activated sludge. Less membrane fouling in SSMBR were also attributed to larger particle size, higher zeta potential and relative hydrophobicity of sludge flocs.

Evaluation of micropollutant removal and fouling reduction in a hybrid moving bed biofilm reactor–membrane bioreactor system

“…Sludge samples were subjected to an extraction process to separate the SMP and EPS (Deng et al, 2014). Zeta potential of suspended solids of the mixed liquor was measured using a Zetasizer Nano ZS (Malvern Instruments, UK).…”

Membrane bioreactor: A mini review on recent R&D works

“…Deng et al (2014) noted that the added sponge can prevent cake formation and pore blockage in a submerged MBR that are mainly contributed by soluble microbial products in activated sludge. Zuthi et al (2015) developed a mathematical model for a sponge submerged membrane bioreactor considering the biomass viability and extra-cellular polymeric substances redundancy.…”

Membrane fouling reduction and improvement of sludge characteristics by bioflocculant addition in submerged membrane bioreactor

“…Subsequently, the removed cake layer was dissolved in 100 mL of distilled water for foulant analysis. The cake layer and mixed liquor were extracted and analyzed with regard to EPS and SMP based on the methods as demonstrated in our previous study [23]. BPC were obtained by following the method proposed by Sun et al [24].…”

“…The zeta potential of mixed liquor was analyzed with a zeta potential meter (Zetasizer Nano ZS, Malvern Instruments, UK). The method reported by Deng et al [23] and Ji et al [17] was applied to determine the relative hydrophobicity (RH) of sludge flocs. Particle size distribution of sludge flocs was determined by analyzing the images obtained by the Olympus System Microscope Model BX41 (Olympus, Japan) with Image-Pro Plus software.…”

“…Overall, the improved aggregation ability of sludge flocs in the MBR-G was ascribed to increased EPS concentrations as well as EPS P /EPS C ratio. Hence, although activated sludge presented higher EPS concentrations, the MBR-G exhibited less membrane fouling propensity with lower fouling rate [23,33]. , respectively.…”