Influence of Internal Biofilm Growth on Residual Permeability Loss in Aerobic Granular Membrane Bioreactors

Abstract

Membrane fouling results in flux decline or transmembrane pressure drop increase during membrane bioreactor (MBR) operation. Physical and chemical cleanings are essential to keep an MBR operating at an appropriate membrane flux. Considerable residual membrane permeability loss that cannot be removed by conventional cleaning requires membrane replacement. This study demonstrates that an internal biofilm can develop inside a hollow-fiber membrane and can probably account for up to 58.9 and 81.3% of total membrane resistance for aerobic granular MBR operated in sequencing batch reactor (SBR) mode or continuous-fed mode, respectively. The Arthrobacter sp. (accession no. AM900505 in GenBank) corresponded to internal biofilm development by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis and the agar-plating technique. This study also identifies a single strain, Arthrobacter sp., generates the internal biofilm. The Arthrobacter sp. is a rod-shaped bacterium with a size close to that of membrane pores, and can secrete excess bound proteins, hence can penetrate and attach itself inside the membrane and grow. Internal biofilm growth could contribute significantly to membrane resistance during long-term MBR operation.

Probing Membrane Fouling via Infrared Attenuated Total Reflection Mapping Coupled with Multivariate Curve Resolution

“…Some spectroscopic technologies, such as confocal laser scanning microscopy and surface‐enhanced Raman scattering (SERS), partially overcome these shortcomings and have been utilized to analyze membrane fouling processes . However, fluorophore labels or SERS substrates are required for applying these methods.…”

Membrane Processes

“…The influence of internal biofilm growth on permeability loss in aerobic granular MBRs was studied (Juang, Adav et al, 2010). This study demonstrates that an internal biofilm can develop inside a hollow-fiber membrane and can probably account for up to 58.9 and 81.3% of total membrane resistance for aerobic granular MBR operated in SBR mode or continuous-fed mode, respectively.…”

Evolution of Membrane Fouling Revealed by Label-Free Vibrational Spectroscopic Imaging

“…Membrane fouling is affected by a variety of factors, including membrane materials and structure, feed properties, and operating conditions. ,,,− Different types of fouling forms have been proposed, including pore constriction, pore blockage, and deposit-forming cake layers. ,− In addition to the conventional approaches, various new techniques have been utilized to characterize membrane fouling processes, such as ultrasonic time domain reflectometry, , electrical impedance spectroscopy, , and 3-dimentional (3D) optical coherence tomography (OCT) imaging . Some of them can provide real-time information on membrane fouling, such as change in porosity and fouling layer formation, but fail to discriminate the different chemical compositions of foulants, which is considered crucial to the evaluation of the roles of foulant species in fouling process.…”