Strains of internal biofilm in aerobic granular membrane bioreactors

Abstract

This study isolated strains in suspended liquor, the surface fouling layer, and biofilm inside hollow-fiber membranes of a membrane bioreactor (MBR); analyzed their distributions, sizes, surface charges, and growth behaviors; and determined the quantities of extracellular polymeric substances (EPS) secreted by these strains under different organic loadings. Three strains, which may penetrate the microfiltration membranes, were close relatives of the Ralstonia mannitolilytica strain SDV (GenBank Accession No. GU451066), Arthrobacter sp. BJQ-2 (GenBank Accession No. GU451067), and Actinobacterium DS3 (GenBank Accession No. GU451068). Among these three strains, only Arthrobacter sp. developed an internal biofilm. The relatively short length of Arthrobacter sp. minimizes resistance to cells moving through the membrane matrix, thereby enhancing its ability to build a biofilm in the interior surface of membranes.

Membrane fouling potentials and cellular properties of bacteria isolated from fouled membranes in a MBR treating municipal wastewater

“…For examples, a strain belonging to Arthrobacter sp. having a relatively small cell size in mixed liquor of an aerobic granular membrane bioreactor (AGMBR) can penetrate the microfiltration (MF) membrane and develop an internal biofilm that induce membrane fouling (Juang et al 2010). Furthermore, biofilm formation potentials of strains isolated from reverse osmosis (RO) membranes treating potable water were measured in microtiter plates and related to their cellular properties such as hydrophobicity, surface charge, and motility (Pang et al 2005).…”

“…Biofilm formation potentials determined in microtiter plates sometimes do not reflect membrane fouling potentials, because convective permeate flow is known to be a major mechanism that transports bacterial cells and EPS to membrane surfaces during filtration (Habimana et al 2014). Therefore, biofilm formation and/or biomass deposition on membrane surfaces, furthermore membrane fouling, are more likely to be independent of bacterial cell surface properties and motility (Habimana et al 2014;Juang et al 2010). Thus, membrane fouling potential must be directly evaluated for each bacterial strain under defined filtration conditions.…”

Fouling characterisation in PVDF membrane contactors for dissolved methane recovery from anaerobic effluents: effect of surface organofluorosilanisation

“…Alkalinity was determined by means of the 5 pH point titration procedure (Moosbrugger et al 1992) (848 Titrino Plus, Metrohm, Switzerland). The polysaccharide content was analysed by the phenol-sulfuric acid method proposed by Dubois et al (1956) with glucose as the standard (Juang et al 2010;Hafuka et al 2019). The protein content was determined according to the modified Lowry methods by Onishi and Bar (Total protein kit, micro Lowry, Onishi & Bar modification, Sigma-Aldrich, USA) using bovine serum albumin as the standard.…”

Membrane fouling induced by AHL-mediated soluble microbial product (SMP) formation by fouling-causing bacteria co-cultured with fouling-enhancing bacteria

“…Extensive studies have been conducted to isolate and characterize key bacteria responsible for membrane fouling 6 – 9 . In our previous study, forty-one bacterial strains were isolated from a pilot-scale MBR treating municipal wastewater, tested for their fouling potential using a cross-flow filtration unit, and related to their cellular properties 8 .…”