Composition Of EPS Research Articles

Enhancing mainstream anammox process by adding Fe3O4 nanoparticles

In order to further promote the application of mainstream anammox, magnetic field enhancing technology was applied to improve the anammox start-up and operation performance under the conditions of low temperature and substrates concentrations. Two UASBs were adopted as anammox reactors and run in parallel. The controlling group and the magnetic field enhancing group (with 2.4 g/L Fe3O4 NPs) were recorded as UASBC and UASBM. The results showed that UASBC and UASBM successfully took 37 days and 33 days to start mainstream anammox with TNRE of 90.03% and 85.05%, respectively. The maximum TNLR of UASBC and UASBM reached 0.54 mg N(m3·d)−1 and 0.82 mg N(m3·d)−1 with the maximum TNRE of 86.41% and 85.50% during 121 days operation. The results showed that magnetic filed could change morphological characteristics of AnAOB and strengthen sludge granulation by adjusting the composition of EPS. Microbial high-throughput sequencing analysis results showed the phylum of Planctomycetes dominated in UASBC and UASBM with the relative abundance of 26.41% and 32.68% on 121 d. Candidatus Kuenenia was cultured as the dominant bacteria, and it was speculated that magnetic filed had the ability to promoting the enrichment of Candidatus Kuenenia. These findings were interesting and meaningful, and could provide new ideas for long-term application of mainstream anammox.

Environmental modulation of exopolysaccharide production in the cyanobacterium Synechocystis 6803

Microorganisms produce extracellular polymeric substances (EPS, also known as exopolysaccharides) of diverse composition and structure. The biochemical and biophysical properties of these biopolymers enable a wide range of industrial applications. EPS from cyanobacteria are particularly versatile as they incorporate a larger number and variety of building blocks and adopt more complex structures than EPS from other organisms. However, the genetic makeup and regulation of EPS biosynthetic pathways in cyanobacteria are poorly understood. Here, we measured the effect of changing culture media on titre and composition of EPS released by Synechocystis sp. PCC 6803, and we integrated this information with transcriptomic data. Across all conditions, daily EPS productivity of individual cells was highest in the early growth phase, but the total amount of EPS obtained from the cultures was highest in the later growth phases due to accumulation. Lowering the magnesium concentration in the media enhanced per-cell productivity but the produced EPS had a lower total sugar content. Levels of individual monosaccharides correlated with specific culture media components, e.g. xylose with sulfur, glucose and N-acetyl-galactosamine with NaCl. Comparison with RNA sequencing data suggests a Wzy-dependent biosynthetic pathway and a protective role for xylose-rich EPS. This multi-level analysis offers a handle to link individual genes to the dynamic modulation of a complex biopolymer.Key points• Synechocystis exopolysaccharide amount and composition depends on culture condition• Production rate and sugar content can be modulated by Mg and S respectively• Wzy-dependent biosynthetic pathway and protective role proposed for xylose-rich EPSGraphical

Suitability of lectin binding studies for the characterization of redox-active microbial environmental biofilms

Aquatic environmental microbial biofilms grow in a broad range of redox environments from oxic to methanogenic, and they often also establish internal redox gradients. In technical applications, biofilms are also subjected to controlled redox conditions. Studies on biofilms often make use of fluorescence microscopic imaging techniques together with lectin binding analysis to gain insights into structure, composition, and functions of the biofilms. Here we studied the direct influence of redox potentials on fluorescence lectin binding analyses (FLBA) for two commonly used lectin-fluorophore conjugates. An effect of the electrical potential on signal intensity was observed and found to be statistically significant. The signal intensity changes however, remained within the range of a few percent total. A significant drop in intensity was only observed for extremely oxidizing potentials, typically not found under environmental conditions. Our results showed that the fluorophore itself and not the lectin binding to the respective glycoconjugate causes fluorescence changes. The two tested lectin-fluorophores are shown to be suitable for studying the distribution and composition of EPS in environmental biofilms or technical applications and under varying redox conditions.

Extracellular polymeric substance profiling and biophysical analysis reveal influence factors of spontaneous flocculation in rich lipid alga Heveochlorella sp. Yu

Microalgae harvest and lipid accumulation were important factors influencing commercialized development of microalgae biodiesel. Spontaneous flocculation was an ideal method in microalgae harvest, but few rich lipid microalgae could be harvested by spontaneous flocculation. Rich lipid alga Heveochlorella sp. Yu has a characteristic of spontaneous flocculation to be harvested. Heveochlorella sp. Yu has high lipid productivity (105.24 mg L−1 d−1) and fine spontaneous flocculation efficiency (82.93 %, 2 h) on early stationary phase (day 9). The polysaccharides consisting of glucose, mannose, galactose, rhamnose and fructose (8.67:4.90:3.27:2.16:1) in loose-bound extracellular polymeric substance (LB-EPS) might make great contribution in microalgae flocculation. Meanwhile, the zeta potential close to zero was also beneficial to microalgae flocculation. Besides, the adhesion free energy related with cells adhesion was detected by thermomechanical analysis. Afterward, Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was utilized to quantitatively evaluate short-range interactions involved in the spontaneous aggregation among cells. Collectively, biophysical analyses indicated that content and composition of EPS, Zeta potential, thermodynamic parameter and total interaction based on XDLVO theory were closely connected with spontaneous flocculation in microalga Yu. Our study provided a harvest-simplified process of rich microalgae, which proposes a new idea for commercial development of microalgae biodiesel.

Mechanism and regulation of filamentous algal-bacterial symbiosis based on microbiological quorum sensing.

In algae-bacteria symbiotic systems, algae and bacteria work cooperatively to reduce aeration demand and carbon emissions during wastewater treatment. However, controlling and stabilizing microbial communities in the conventional algae-bacteria symbiotic systems are complicated and unstable. We, therefore, developed a novel sewage treatment system based on a filamentous algae-bacterial symbiotic granule system (AB) in a photo-sequencing batch reactor (PSBR). The exogenous signal molecules (i.e., N-acyl-homoserine lactones [AHLs]) were applied to promote the algae-bacteria consortia formation. The characteristics and performance of the mature algae-bacterial granular consortia were investigated and then compared with that of the activated sludge (AS) system under identical operating conditions. The chemical oxidation demand (COD) removal efficiencies were greater than 90% in the dynamic synergistic investigation, even without aeration. However, the addition of AHLs (5, 50, and 200 nmol/L) had a negligible effect on treatment performance. In static conditions, 10-9nmol/L of AHLs can significantly regulate the algae-bacteria symbiotic system, and AHLs (<50 nmol/L) improved COD and NH4 + removal efficiencies by up to 90%. Moreover, the addition of AHLs augmented polysaccharide secretion but had little effect on protein secretion. In comparison to the AS system, the AB system demonstrated promise in terms of pollution removal efficiency and microbial diversity enhancement. PRACTITIONER POINTS: Oscillatoria can serve as an excellent biological carrier for immobilizing bacteria. AHLs (10-9mol/L) regulated the operation state of algae-bacteria symbiotic system. AHLs altered the composition and content of EPS in the algae-bacteria system.

Aerobic Granular Sludge Operation and Nutrient Removal Mechanism from Domestic Sewage in an Anaerobic/Aerobic Alternating Continuous Flow System

Mature aerobic granular sludge was inoculated at room temperature in an anaerobic/aerobic alternating continuous flow system. The system consisted of two independent anaerobic and aerobic tanks. Actual domestic sewage was used as the influent to explore the influence of the gas intensity and hydraulic residence time on the continuous flow system. The results revealed that the conditions of a reflux ratio of 2, lower aeration intensity (0.6 mL·min-1), and proper hydraulic residence time (9 h) were more conducive to the removal of pollutants. Under such conditions, the average removal rate of TP was 80.43%, the average removal rate of TN was 83.6%, the average removal rate of COD was 90.39%, the sludge concentration was approximately 2100 mg·L-1, the sludge volume index was maintained below 50 mL·g-1, and the particle size was 700-800 nm. The EEM-PARAFAC model was used to characterize and analyze the EPS at different stages. The results revealed that changing the parameters could change the composition of EPS. The hydraulic residence time had a greater impact on the continuous flow system than the aeration intensity. In addition, a preliminary conceptual reaction process model in the anaerobic/aerobic alternating continuous flow system was built using high-throughput pyrosequencing and phylogenetic assignment. Eleven major functional bacteria related to nitrogen and phosphorus removal were found in the system.

Quercetin Inhibits Biofilm Formation by Decreasing the Production of EPS and Altering the Composition of EPS in Staphylococcus epidermidis

Staphylococcus epidermidis is an opportunistic pathogen, and its biofilm formation ability is an important virulent factor. Quercetin, a typical flavonoid ubiquitously used in dietary supplementation, is known for its antioxidant property, but its anti-biofilm activity against S. epidermidis remains unknown. In this study, the anti-biofilm activity of quercetin was investigated using S. epidermidis ATCC35984, a strong biofilm-positive strain. An attempt was made to disclose the mechanisms of the anti-biofilm activity of quercetin. S. epidermidis exhibited a less cell surface hydrophobicity after quercetin treatment. Also, quercetin effectively inhibited S. epidermidis cells from adhering to the glass slides. Quercetin downregulated the intercellular adhesion (ica) locus and then polysaccharide intercellular adhesin (PIA) production was reduced. Therefore, S. epidermidis cells became less hydrophobic, which supported quercetin’s anti-biofilm effect. Our study suggests that quercetin from plants be given further attention as a potential anti-biofilm agent against the biofilm formation of S. epidermidis, even biofilm infections of other bacteria.

Newly Isolated Acidithiobacillus sp. Ksh From Kashen Copper Ore: Peculiarities of EPS and Colloidal Exopolysaccharide.

A novel strain of an iron- and sulfur-oxidizing bacterium was isolated from a natural biotope at Kashen copper ore (Martakert Province, Republic of Artsakh). The strain is able to grow and oxidize ferrous ions in the range of pH 1.4–2.6 with optimal pH 2.0. The optimal temperature for growth is 35°C. Acidithiobacillus sp. Ksh has shown the highest activity for pyrite oxidation among other strains. It also demonstrated high activity in oxidation for copper and copper-gold bearing ores (Armenia). The isolate Acidithiobacillus sp. Ksh was identified as Acidithiobacillus ferrooxidans based on phylogenetic and physiological studies. Comparative studies of EPS production by cells grown on ferrous ions or pyrite were carried out. The chemical composition of capsular and colloidal EPS produced by Acidithiobacillus (At.) ferrooxidans Ksh were revealed to be proteins and carbohydrates. Exosaccharide produced by At. ferrooxidans Ksh is present mainly as polysaccharide in contrast to Leptospirillum (L.) ferriphilum CC, which is oligosaccharide. The structural difference of colloidal particles of these polysaccharides was due to the degree of hydration of the saccharide molecules.

A novel exopolysaccharide produced by Lactobacillus coryniformis NA-3 exhibits antioxidant and biofilm-inhibiting properties in vitro.

BackgroundExopolysaccharides (EPSs) secreted from lactic acid bacteria are carbohydrate polymers with reported biological activities. In this study, we extracted and characterized the composition as well as antioxidant and biofilm-inhibitory properties of EPS from Lactobacillus coryniformis NA-3 isolated from northeast Chinese sauerkraut (Suan Cai).MethodsLactobacillus coryniformis NA-3 was identified with 16S rDNA amplification and Neighbor Joining (NJ) phylogenetic analysis. EPS derived from Lactobacillus coryniformis NA-3 (EPS-NA3) was analyzed, including compositions by high-performance liquid chromatography (HPLC), functional groups by Fourier-transform infrared spectroscopy (FT-IR) and glycosidic bond configuration by Hydrogen-1 Nuclear Magnetic Resonance (1H NMR). Antioxidant activity of EPS was evaluated with hydroxyl and superoxide radical-scavenging. Anti-biofilm activities of EPS-NA3 were checked through inhibition and dispersion.ResultsThe monosaccharide composition of EPS included α-rhamnose, α-mannose, α-galactose, and α-glucose in a ratio of 2.6:1.0:5.0:3.3. The free radical-scavenging abilities of EPS-NA3 were 37.77% ± 1.56% and 78.87% ± 3.07% on hydroxyl and superoxide reactive oxygen species respectively. Moreover, EPS-NA3 attenuated the formation of Bacillus cereus and Salmonella typhimurium biofilms by inhibition ratios of approximately 80% and 40% respectively. Additionally, treatment with EPS-NA3 dispersed established biofilms of B. cereus and S. typhimurium by approximately 90% and 20% respectively.ConclusionThese results suggest that EPS-NA3 may be developed as antioxidant and anti-biofilm agents for industrial and clinical applications due to its capacity of scavenging free radicals, inhibition of bacterial biofilm formation, and dispersion of established biofilms.

Correlation between oxidation-reduction potential values and sludge dewaterability during pre-oxidation

Pre-oxidation is effective in enhancing sludge dewaterability. Different types and doses of oxidants are used to improve sludge dewaterability in pre-oxidation. Rapid evaluation of the sludge dewaterability is vital for optimizing the type and dose of oxidants in pre-oxidation. It normally takes more time to evaluate sludge dewaterability by measuring typical indicators such as specific resistance to filtration (SRF), content of bound water, and composition of EPS. This study presented a rapid parameter, oxidation-reduction potential (ORP), to correlate it with the dewaterability of pre-oxidized sludge samples. An index of ΔORP (ΔORP = ORPt=0.5 min–ORPt=0 min) showed positive correlations with SRF (r = 0.89, p < 0.05), content of total organic carbon in soluble and loosely-bound EPS (r = 0.86 and 0.84, p < 0.05), zeta potential (r = 0.86, p < 0.05), and content of Fe(III) in the sludge cake (r = 0.92, p < 0.01). However, the ΔORP index showed negative correlations with tryptophan-like proteins, tyrosine-like proteins, microbial byproduct-like materials in tightly-bound EPS (r = −0.85, −0.90 and −0.90, p < 0.05), and sludge particle sizes (p < 0.01). A multiple linear regression model was developed to further reflect the linear correlation between the ΔORP values and the key factors reflecting sludge dewaterability. An optimal dose of oxone (0.4 mmol/g VS) for sludge pre-oxidation with the ΔORP value of 387 mV combined with Fe(III) coagulation conditioning system were verified by the results of dewatering experiments using a laboratory-scale diaphragm filter press. This study demonstrated the feasibility of using ΔORP as a potential rapid evaluation tool for sludge dewaterability.

Characteristics of Biofilm During the Transition Process of Complete Nitrification and Partial Nitrification

The objective of the study was to investigate the change of biofilm characteristics when implementing the procedure of partial nitrification. A ratio control strategy (DO/NH4+-N) was taken to achieve partial nitrification, and biofilm samples were obtained at 10.27%, 52.12%, and 93.54% of the nitrite accumulation rate. The amount and spatial distribution of total bacteria, ammonia oxidizing bacteria (AOB), and nitrite oxidative bacteria (NOB) were observed by fluorescence in situ hybridization (FISH) and confocal laser scanning microscope (CLSM) through a three-dimensional excitation emission matrix (EEM) to observe the secretion and composition changes of extracellular polymer substances. Ratio control successfully enriched AOB and achieved partial nitrification under conditions when NOB was not completely washed. Heterotrophic bacteria and nitrifying bacteria coexist in the biofilm. The heterotrophic bacteria were in the outer layer, but nitrifying bacteria were distributed in the biofilm surface at 6-25 μm. During the process of short-range nitrification, the AOB/NOB value gradually increased, and the stable operation period was as high as 15.56. During the operation of the reactor, EPS and microbial flora changes are closely related. When microbial activity decreased, EPS secretion decreased. During the stable operation period of partial nitrification, NOB and other bacteria that are non-resistant to high nitrite nitrous acid declined, and the fluorescence intensity of aromatic protein-like bacteria decreased. However, the three-dimensional fluorescence spectra showed that the chemical composition of EPS was not obvious during the process of partial nitrification.

Composition of Extracellular and Intracellular Polymeric Substances Produced by Scenedesmus and Microcystis

Abstract Algal extracellular and intracellular polymeric substances (EPS and IPS) are widely applied in fields such as food, cosmetics, and wastewater treatment. Algal IPS content was much higher than EPS and thus extracting IPS from algal biomass may greatly improve the commercial value of algal cultivation. This study was to provide a basis for development of algal IPS by comparing composition of algal IPS and EPS. EPS and IPS produced by Scenedesmus and Microcystis, which commonly dominates the freshwater ecosystems, were analyzed using fluorescence excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). The IPS concentration of Scenedesmus obliquus and Microcystis aeruginosa was 1.2 to 2.1 times higher than EPS concentration. The maximum EPS concentration was 145.7 mg C/L but the maximum IPS concentration reached 206.1 mg C/L. Seven components including five humic-like components (C1, C2, C3, C4, and C7) and two tryptophan-like component (C5 and C6) were identifie...

Unified understanding of physico-chemical properties of activated sludge and fouling propensity

A range of parameters affecting floc characteristics, sludge composition and filtration properties was investigated by analyzing 29 sludge samples from municipal and industrial conventional activated sludge systems and municipal membrane bioreactors (MBR). Samples were characterized by physico-chemical parameters, composition of ions and EPS, degree of flocculation, settling properties, dewatering properties, and filtration properties. By analyzing the interplay between various metrics instead of single parameters, a unified understanding of the influence of sludge composition and characteristics was developed. From this, a conceptual model was proposed to describe the interplay between sludge composition, characteristics, and filtration properties. The article shows three major results contributing to describe the interplay between sludge characteristics and fouling propensity: First, the degree of flocculation could be quantified by the ratio between floc size and residual turbidity and was a key parameter to assess fouling propensity. Second, extracted EPS to polyvalent cations ratio was used as an indicator of the flocculation. A high ratio combined with a high concentration of EPS resulted in large, loosely bound, and weak flocs that were easily deformed, hence giving compressible fouling layers. Finally, high amounts of carbohydrates in both total and extracted EPS resulted in more pronounced fouling, which may be explained by carbohydrates forming poorer flocs than humic substances and proteins. Accordingly, samples with high humic content showed lower specific resistance to filtration due to better floc structure. The amount of carbohydrates in EPS correlated positively to the influent COD/N ratio, which may explain why systems with high influent COD/N ratio demonstrated higher fouling propensity.

Exopolysaccharide production in Anabaena sp. PCC 7120 under different CaCl2 regimes.

Influence of various levels of CaCl2 (0, 1, 10 and 100mM) on exopolysaccharide production has been investigated in the cyanobacterium Anabaena 7120. At the concentration of 1mM CaCl2, growth was found to be stimulatory while 100mM was sub lethal for the cyanobacterial cells. Estimation of EPS content revealed that EPS production depends on the concentration of calcium ions in the immediate environment with maximum being at10mM CaCl2. A possible involvement of alr2882 gene in the process of EPS production was also revealed through qRT-PCR. Further, FTIR-spectra marked the presence of aliphatic alkyl-group, primary amine-group, and polysaccharides along with shift in major absorption peaks suggesting that calcium levels in the external environment regulate the composition of EPS produced by Anabaena 7120. Thus, both quantity and composition of EPS is affected under different calcium chloride concentrations presenting possibilities of EPS with novel unexplored features that may offer biotechnological applications.

Biofilm Formation and Extracellular Polymeric Substances (EPS) Analysis by New Isolates of &lt;i&gt;Leptospirillum&lt;/i&gt;, &lt;i&gt;Acidithiobacillus&lt;/i&gt; and &lt;i&gt;Sulfobacillus&lt;/i&gt; from Armenia

Biofilm formation by new isolates, Leptospirillum sp. strain ZC, Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6 isolated from different biotopes of sulfide ores in Armenia on pyrite was studied by atomic force microscopy (AFM) combined with epifluorescence microscopy (EFM). It was revealed that all the tested species formed monolayer biofilms The results showed that in contrast to Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6, cells of Leptospirillum sp. strain ZC were often observed by clusters and aggregates.The composition of capsular and colloidal EPS formed by isolated Leptospirillum sp. strain ZC, Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6 was studied. It was revealed that the EPS of all three species grown on iron (II) mainly consisted of carbohydrates, proteins as well as uronic acids.

Urinary catheter indwelling clinical pathogen biofilm formation, exopolysaccharide characterization and their growth influencing parameters

Self-reproducing microbial biofilm community mainly involved in the contamination of indwelling medical devices including catheters play a vital role in nosocomial infections. The catheter-associated urinary tract infection (CA-UTI) causative Staphylococcus aureus, Enterobacter faecalis, and Pseudomonas aeruginosa were selectively isolated, their phenotypic as well as genotypic biofilm formation, production and monomeric sugar composition of EPS as well as sugar, salt, pH and temperature influence on their in vitro biofilm formation were determined. From 50 culture positive urinary catheters S. aureus (24%), P. aeruginosa (18%), E. faecalis (14%) and others (44%) were isolated. The performed assays revealed their varying biofilm forming ability. The isolated S. aureus ica, E. faecalis esp, and P. aeruginosa cup A gene sequencing and phylogenetic analysis showed their close branching and genetic relationship. The analyzed sugar, salt, pH, and temperature showed that the degree of CA-UTI isolates biofilm formation is an environmentally sensitive process. EPS monosaccharide HPLC analysis showed the presence of neutral sugars (ng/μl) as follows: glucose (P. aeruginosa: 44.275; E. faecalis: 4.23), lactose (P. aeruginosa: 7.29), mannitol (P. aeruginosa: 2.53; S. aureus: 2.62; E. faecalis: 2.054) and maltose (E. faecalis: 7.0042) revealing species-specific presence and variation. This study may have potential clinical relevance for the easy diagnosis and management of CA-UTI.

Metal removal of cyanobacterial exopolysaccharides by uronic acid content and monosaccharide composition

In the present study, chromium, cadmium and metal mixed (chromium+cadmium) removal and its association with exopolysaccharides and uronic acids production in Synechocystis sp. BASO671 were investigated. It was investigated that BASO671 showed different removal ability when exposed to each metal solely and mixed metal. EPS production by BASO671 was increased following exposure to 15 and 35ppm Cr(VI), Cd(II) and Cr(VI)+Cd(II). Monomer composition of EPS was changed after metal treatment. Uronic acid contents of metal treated cells were higher than control cells of each isolate. Also, glucuronic acid content and galactronic acid content of EPS correlated with uronic acid contents of cells. Scanning electron microscopy and energy dispersive X-ray spectroscopy analysis confirmed that a considerable amount of metals had precipitated on the cell surface. Fourier transform infrared spectrum analysis of EPSs indicated the presence of CH and CO group, which may serve as binding sites for divalent cations.

A prototype IT/BF–MBR (inclined tube/biofilm-membrane bioreactor) for high-rise building wastewater recycling

A novel inclined-tube biofilm-membrane bioreactor (IT/BF-MBR) has been developed in a prototype system for high-rise building wastewater recycling. The prototype IT/BF-MBR system was designed as a single compact reactor with three compartments, starting from first-stage biofilm compartment, second-stage biofilm compartment and aerobic membrane compartment with submerged MF membrane installation. Here, the inclined tube was installed as a prefilter for sieving and filtering the incoming suspended solid and also served as a media to promote biofilm growth in the biofilm compartments to enhance more biomass activity inside the IT/BF-MBR system. The system received raw wastewater from a 20-floor university building at a design flow rate capacity of 4 m3/day. The IT/BF-MBR could achieve stable treatment performance as above 90% removal efficiencies for organic Chemical oxygen demand, NH4+–N, and total phosphorus. The composition of microbial EPS inside the membrane bioreactor system was found in the following order: lipid ##xgt; carbohydrate ##xgt; protein. Furthermore, the quality of treated effluent could comply with the reuse water quality standard for nonpotable uses as toilet flushing and garden watering purposes.

A model for the structures of impact polypropylene copolymers produced by an atmosphere-switching polymerization process

This work reports on the development of a model to establish the relationship between the structures of impact polypropylene copolymer (IPC), a high performance polymer material, and the characteristics of an atmosphere-switching polymerization process (ASPP), a new polymerization route. To calculate the complex structures of IPC, a detailed kinetic mechanism was proposed to describe the kinetic behavior of the active centers of Ziegler–Natta catalyst during ASPP. The semibatch ASPP for synthesizing IPC was carried out for the model validation. The model is capable of predicting the evolution of the compositional distributions of IPC as a function of switching frequency (SF), which is the main characteristic parameter of ASPP. ASPP not only allows controlling the contents of ethylene–propylene random copolymers (EPR) and ethylene–propylene segmented copolymers (EPS,) but also tuning the composition of EPS. Other applications of the model are discussed.

Performance and fouling characteristics of different pore-sized submerged ceramic membrane bioreactors (SCMBR)

The membrane bioreactor (MBR), a combination of activated sludge process and the membrane separation system, has been widely used in wastewater treatment. However, 90% of MBR reported were employing polymeric membranes. The usage of ceramic membranes in MBR is quite rare. Four submerged ceramic membrane bioreactors (SCMBRs) with different membrane pore size were used in this study to treat sewage. The results showed that the desirable carbonaceous removal of 95% and ammonia nitrogen removal of 98% were obtained for all the SCMBRs. It was also showed that the ceramic membranes were able to reject some portions of the protein and carbohydrate, whereby the carbohydrate rejection rate was much higher than that of protein. Membrane pore size did not significantly affect the COD and TOC removal efficiencies, the composition of EPS and SMP or the membrane rejection rate, although slight differences were observed. The SCMBR with the biggest membrane pore size fouled fastest, and membrane pore size was a main contributor for the different fouling potential observed.