Biofouling Layer Research Articles

The growth process of the cake layer and membrane fouling alleviation mechanism in a MBR assisted with the self-generated electric field

The electric field assisted membrane bioreactor (MBR) is an effective technique to alleviate membrane fouling. In this study, the spontaneous electric field was introduced into the MBR to observe the growth process of cake layer on the membrane surface. The external resistance for spontaneous electric field MBR (S-50) and S-500 were 50 Ω and 500 Ω respectively. During the experiments, S-50 maintained the highest electric field intensity of 11.83 mV/cm. The reduction of extracellular polymeric substances (EPS) content in activated sludge, transmembrane pressure (TMP) growth rate reached 52.8% and 51.7% respectively. After 28 days operation, S-50 obtained the minimum contaminant specific biovolume (23.316 μm3/μm2), which was 68.2% lower than that of it in Control-MBR. The metal oxide or metal hydroxide were distributed in the cake layer. EPS played a significant role in the formation and growth of the cake layer. Based on the results obtained in this study, the growth of the biofouling layer on the membrane surface could be divided into three stages. EPS first deposited on the membrane surface, and then microorganisms embedded in the cake layer to form clusters. After that, EPS and total cells further increased and led to a faster biovolume growth rate. Subsequently, the biovolume growth rate decreased in the cake layer. The spontaneous electric field delayed the deposition of EPS on the membrane surface. The produced H2O2 and •OH were beneficial to the degradation of organics, causing the smaller contaminant biovolume on the membrane surface. This work aims to provide a theoretical basis for the practical application of the electric field to control membrane fouling.

Biofouling layer maintains low hydraulic resistances and high ammonia removal in the UF process operated at low flux

In this study, the hydraulic resistance and pollutant removal efficiency of the biofouling layer (i.e., biofilm) were investigated in the ultrafiltration (UF) systems operating at various flux (i.e., 10, 15, 20, and 30 L/m2·h). The results showed that the biofouling layers successfully removed ammonia (70–100%) and assimilable organic carbon (AOC) (47–55%) although their thicknesses were approximately 50–200 μm. The ammonia removal efficiency exponentially increased as the average time of water passing through the biofouling layer increased. The fouling resistance sharply increased at the flux of 30 L/m2·h, while a negligible increase was observed at the flux of 10 L/m2·h. Moreover, membrane fouling was low even without backwashing or air sparging at the flux of 10 L/m2·h. According to the observation from optical coherence tomography (OCT) and the analysis of the specific resistance of biofouling layers, these phenomena of low fouling were related to the thin and loose biofouling layers at low flux, which formed because of the low accumulation of foulants, low compression of the biofouling layer at low trans-membrane pressures, and the activity of microorganisms. These findings suggested that we can utilize the benefits of biofouling to remove specific pollutants without a remarkable increase in fouling resistances.

Balancing carbon, nitrogen and phosphorus concentration in seawater as a strategy to prevent accelerated membrane biofouling

Membrane biofouling remains a significant challenge in seawater reverse osmosis desalination for drinking water production. This study investigated nutrient imbalance as the cause of biofouling in lab-scale experiments and carried out a year-long field-testing at a seawater desalination pilot plant. Lab experiments showed that growth medium with excess of organic carbon (C) but with low nitrogen (N) and phosphorus (P) accelerated the formation of bacterial biofilm. Balancing C to N and P ratios by adding N and P to growth medium increased the proliferation of free-living cells but reduced attached form of bacteria as biofilm. The cell excretion of excess C in the form of extracellular polysaccharides (EPS) was considered as a strategy for nutrient storage for future use. Cell enzyme activity assays indicated some of the bacteria had enhanced enzyme activities to degrade polysaccharides in the absence of organic C in growth medium, possibly using EPS in the biofilm. A year-long field study indicated that accelerated biofouling of seawater reverse osmosis (SWRO) membranes was associated with the elevated content of total organic carbon (TOC) in the intake seawater. Adding N and P to the intake seawater to balance the increase of TOC resulted in reduction of membrane biofouling. Microbial community analysis of the biofouling layer using 16S rRNA gene sequencing indicated biofouling communities varied with seasonal changes. Dosing of N and P did not induce dramatic changes in the fouling microbial community growing on the membrane surface. The outcome of this work implies that membrane biofouling associated with the elevated concentration of TOC in intake seawater is caused by imbalance of C:N:P in the source seawater which occurs often during algal blooms. Addition of N and P to rebalance the nutrients can prevent accelerated SWRO membrane biofouling.

Evaluating the performance of gravity-driven membrane filtration as desalination pretreatment of shale gas flowback and produced water

The shale gas extraction industry generates a large quantity of highly contaminated flowback and produced water (FPW), with great impacts on human health and the environment. In this study, gravity-driven membrane (GDM) filtration was evaluated over a 612-day period as a pre-treatment of FPW for its subsequent desalination. The various investigated GDM systems showed similar contaminant removals, and their steady-state fluxes (i.e., 0.65–0.82 L/(m2·h)) were not significantly correlated to membrane configurations or to the hydrostatic pressures. The flux decline was primarily due to a reversible resistance, which accounted for a large proportion (>89%) of the total hydraulic resistance. Compared to traditional ultrafiltration, the GDM pretreatment resulted in better desalination performance for the subsequent nanofiltration or reverse osmosis step, which were characterized by higher organic removal and generally higher permeate fluxes. More than 60 bacterial genera and 8 eukaryotic genera were detected in the shale gas FPW, with the kingdoms Alveolata and Stramenopiles (within the eukaryote domains) reported for the first time. The biofouling layer of GDMs had a lower bacterial diversity but a higher eukaryotic diversity than the FPW feed water. The eukaryotic community, including Alveolata, Fungi, Stramenopiles and Metazoa, played a major role in the flux behavior.

Thin-film nanocomposite membranes incorporated with water stable metal-organic framework CuBTTri for mitigating biofouling

Thin-film composite (TFC) polyamide membranes are the most commonly used membrane materials for reverse osmosis (RO) processes; however, the high biofouling propensity is one of major limitations to the widespread application of TFC membranes. In this study, we developed an antibiofouling thin-film nanocomposite (TFN) membrane by incorporating a copper-based water-stable metal-organic framework (MOF), CuBTTri, in the active layer. Results showed that the presence of MOFs in the TFN active layer significantly increased membrane water permeability without compromising selectivity. Furthermore, the incorporation of CuBTTri imparted the TFN membrane with efficient antibacterial properties. After 24 h contact, the colony forming units (CFU) of Pseudomonas aeruginosa on the TFN membrane (with a dosage of 0.1% MOF) was 3.4% of that on the pristine membrane, demonstrating a strong antibiofouling behavior. The cross-flow filtration tests further confirmed the antibiofouling performance of the TFN membrane, with a significantly lower flux decline (∼36%) compared to the control (∼70% flux decline). The TFN membranes also had a thinner biofouling layer and less quantity of biofoulants on their surface compared to the TFC membrane. The antibiofouling properties of the TFN membrane were associated with bacterial membrane potential depolarization and cell damage due to the contact with MOF. These results highlight the potential of water-stable MOFs to be used as functional materials to fabricate antibiofouling TFN membranes for advanced water and wastewater treatment.

Effects of water temperature and light intensity on the performance of gravity-driven membrane system

The selection of favorable environmental conditions for gravity-driven membrane (GDM) systems is crucial to their widespread application. In this study, GDM systems operated under different light intensities (illuminance levels of 0, 200, and 3000 Lux) and water temperatures (10, 20, and 30 °C) were investigated for their performance and fouling layer characteristics. The results showed that indoor light (200 Lux) had limited effects on the performance of the GDM system. However, full daylight (3000 Lux) led to algal growth; these algae increased fouling resistance and deteriorated permeate water by releasing algogenic organic matter, although they could also enhance the heterogeneity of the biofouling layer by increasing the microbial activity. Water temperature rarely influenced the total organic matter removal. The fouling layers had different thicknesses and heterogeneity, but the same level of EPS; therefore, the hydraulic resistances of these fouling layer were almost the same at different water temperatures. These findings suggest that GDM system could be operated at low water temperature and indoor light conditions, and that strong light should be avoided during the operation of GDM systems.

Biofouling in ultrafiltration process for drinking water treatment and its control by chlorinated-water and pure water backwashing

We investigated biofouling in ultrafiltration (UF) for drinking water treatment and its control by backwashing with chlorinated-water or pure water. By using sodium azide to suppress biological growth, the relative contribution of biofouling to total fouling was estimated, and its value (5.3–56.0%) varied with the feed water, and increased with the increases of filtration time and membrane flux. The biofouling layer could partially remove biodegradable organic matter and ammonia (32.9–74.2%). Backwashing using chlorinated-water partly inactivated the microorganisms (23.8%) but increased the content of extracellular polymeric substances (7.7%) in the biofouling layer. In contrast, backwashing using pure water led to a looser and more porous fouling layer according to optical coherence tomography observation. Consequently, the latter was more effective in reducing fouling resistance (33.41% reduction) compared to backwashing by chlorinated-water (8.6%). These findings reveal the critical roles of biofouling in pollutants removal in addition to membrane permeability, which has important implications for addressing seasonal ammonia pollution.

Simultaneously recovering electricity and water from wastewater by osmotic microbial fuel cells: Performance and membrane fouling

Since the concept of the osmotic microbial fuel cell (OsMFC) was introduced in 2011, it has attracted growing interests for its potential applications in wastewater treatment and energy recovery. However, forward osmosis (FO) membrane fouling resulting in a severe water flux decline remains a main obstacle. Until now, the fouling mechanisms of FO membrane especially the development of biofouling layer in the OsMFC are not yet clear. Here, the fouling behavior of FO membrane in OsMFCs was systematically investigated. The results indicated that a thick fouling layer including biofouling and inorganic fouling was existed on the FO membrane surface. Compared to the inorganic fouling, the biofouling played a more important role in the development of the fouling layer. Further analyses by the confocal laser scanning microscopy (CLSM) implied that the growth of biofouling layer on the FO membrane surface in the OsMFC could be divided into three stages. Initially, microorganisms associated with s-D-glucopyranose polysaccharides were deposited on the FO membrane surface. After that, the microorganisms grew into a biofilm caused a quick decrease of water flux. Subsequently, some of microorganisms were dead due to lack of nutrient source, in the meantime, polysaccharide and proteins in the biofouling layer were decomposed as nutrient source, thus leading to a slow development of the biofouling layer. Moreover, the microorganisms played a significant role in the formation and development of the biofouling layer, and further studies are needed to mitigate the deposition of microorganisms on FO membrane surfaces in OsMFCs.

Biological pre-treatments enhance gravity-driven membrane filtration for the decentralized water supply: Linking extracellular polymeric substances formation to flux stabilization

Abstract Gravity-driven membrane (GDM) filtration is a promising technology for decentralized drinking water treatment due to its low energy requirements and simple operation. The reduced flux observed in GDM systems relative to other membrane treatment techniques remains a vital obstacle to their wider application. With the goal of further improving membrane flux and permeate quality, three simple and practical technologies have been examined as pre-treatments for GDM systems, (i) slow filtration with granular activated carbon (GAC), expected to remove both biodegradable and non-biodegradable contaminants, (ii) slow filtration with modified fiber ball (MFB), expected to promote biodegradation of organic compounds and (iii) microfiltration (MF), expected to reject suspended substances and particles. Results indicated that stable permeability increased by approximately 230%, 150% and 100% in GDM systems employing GAC, MFB and MF pre-treatments compared to the control. The dissolved organic compounds (DOC) were removed by approximately 60% and 30% in GAC/GDM and MFB/GDM, while MF/GDM and GDM control were not effective at DOC removal. Correlations between the stable flux and extracellular polymeric substances (EPS) concentration (R2 > 0.9) indicated that reduction of EPS should be responsible for the flux improvements. Tracing the fate of florescent foulants illustrated that the EPS was mainly secreted/converted by the microbes colonizing within the bio-fouling layer of the GDM system. During long-term filtration, assimilable organic compounds (AOC) which can serve as nutrients for the growth of microbes within the bio-fouling layer were efficiently consumed (>50%) by the biological pre-treatments. This reduction in AOC was linked with a reduction in the growth/activity of bacteria within the bio-fouling layer of GDM system and a reduction in EPS accumulation. Overall, biological pre-treatments can significantly enhance the flux and water quality produced by a GDM system without significantly increasing the operation and maintenance. These improvements in flux and water quality can hopefully spark wider adoption of GDM as an economical and environmentally-friendly technology for decentralized drinking water treatment.

Characterization of the alteration processes of historical glasses on the seabed

Glass objects are common in shipwrecks since they are associated with ordinary glassware or commercial products. The alteration pathologies of historical glasses from two wrecks from the Mediterranean Sea were analyzed to characterize their alteration mechanisms. The results of this research proved that the alteration layers presented a moderate content of Na2O, similar to the average salinity of the ocean, and a high content of Al2O3 due to an extremely basic environment during the corrosion process. The biofouling layer protected the glass surfaces. Dark deposits with a high content of MnO were observed in the most instable glass.

Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewater

This study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor for real sewage employing baffles in the reactor. To study the biofouling development on forward osmosis membranes optical coherence tomography (OCT) technique was employed. On-line monitoring of biofilm growth on a flat sheet cellulose triacetate forward osmosis (CTA-FO) membrane was conducted for 21 days. Further, the process performance was evaluated in terms of water flux, organic and nutrient removal, microbial activity in terms of soluble microbial products (SMP) and extracellular polymeric substance (EPS), and floc size. The measured biofouling layer thickness was in the order sodium chloride (NaCl) > ammonium sulfate (SOA) > potassium dihydrogen phosphate (KH2PO4). Very high organic removal (96.9 ± 0.8%) and reasonably good nutrient removal efficiency (85.2 ± 1.6% TN) was achieved. The sludge characteristics and biofouling layer thickness suggest that less EPS and higher floc size were the governing factors for less fouling.

Predicting Transmembrane Pressure Rise from Biofouling Layer Compressibility and Permeability

AbstractThe operation of filtration membranes for wastewater treatment is severely affected by biofouling formation, which causes a rapid increase in transmembrane pressure (TMP) in constant rate filtration. The TMP rise is often attributed to particulate fouling within the membrane, but the external fouling layer or filter cake contributes significantly. The fouling is highly compressible, so any model must incorporate cake compression. A one‐dimensional controlled rate model based on compressible cakes and accurate sludge properties is proposed to predict the TMP rise needed to maintain constant flux. Increased compressibility results in more rapid TMP rise. Model predictions were compared to pilot‐plant data and showed good correlation, without assuming fouling within the membrane. Optimization of cycle times and flux rates are performed.

Effects of GAC layer on the performance of gravity-driven membrane filtration (GDM) system for rainwater recycling

Gravity-driven membrane filtration (GDM) is promising for decentralized rainwater recycling, owing to low maintenance and energy consumption. However, the organic removal by GDM process is sometimes undesirable and the quality of the permeate cannot meet the standard of water reuse. To improve this, granular activate carbon (GAC) was added as a particle layer on the membrane surface of GDM system. Additionally, a system with sand addition and a system with no particle addition were trialed as comparisons, to study the combined effects of particle hindering and adsorption on the removal efficacy of organics and the development of permeate flux. Results showed that GDM with a GAC layer improved removal efficiency of organics by 25%, and that GAC enhanced removal of florescent compounds (e.g., aromatic proteins, tryptophan proteins and humics), compared with the other two systems. Additionally, the permeate flux in three systems stabilized after Day 25, and kept stable until the end of the operation. However, the presence of GAC layer decreased the level of stable flux (3.2 L/m2h) compared with the control system (4.5 L/m2h). The factors responsible for the lower flux and severe membrane fouling in GAC layer assisted system were the combined effects of particle and adsorption which led to a denser bio-fouling layer with higher amount of biomass and extracellular polymeric substances contents (proteins and polysaccharides). Resistance distribution analyses revealed that GAC layer mainly increased hydraulically reversible resistance (occupied 93%) of the total resistance, indicating that the flux could be recovered easily by simple physical cleaning.

Coupling GAC to ultra-low-pressure filtration to modify the biofouling layer and bio-community: Flux enhancement and water quality improvement

An integrated gravity-driven membrane (GDM) and granular activated carbon (GAC) filtration process was operated for 193days to investigate the influence of integrated GAC on the flux stabilization, permeate quality, composition of the biofouling layer and eukaryotic community compared with a GDM control system. The results revealed that the presence of GAC resulted in a strongly increased stable flux (6Lm−2h−1, compared to 2Lm−2h−1 in the GDM control). Furthermore, the GAC/GDM system exhibited a significant removal of dissolved organic compounds (DOC) (50–70%) due to the adsorption and biodegradation process. By contrast, the DOC in the permeate of the control was approximately 20–30% higher than in the raw water, which was attributed to the hydrolysis of high-MW compounds. Furthermore, the composition of the biofouling layer attached on the membrane surface was significantly influenced by the presence of GAC, leading to a reduction of accumulated organic compounds by 60%. Likewise, the extracellular polymeric substances (EPS) were obviously reduced in the GAC/GDM system, especially the tightly bound EPS in the biofilm and EPS deposited in membrane pores. Additionally, the GAC could function asa eukaryotic pre-incubator, resulting in a higher diversity of the eukaryotic community and improving predation in the biofouling layer. Furthermore, a more porous, heterogeneous and permeable biofouling layer was observed in GAC/GDM. The higher flux in GAC/GDM system was attributed to (i) lower organic foulants (especially EPS) accumulated in the biofouling layer and membrane pores and (ii) highly heterogeneous structures due to improved activity of eukaryotes in the biofouling layer. These results are essential to develop robust maintenance-free, cost-effective and energy-efficient drinking water treatments.

A low energy gravity-driven membrane bioreactor system for grey water treatment: Permeability and removal performance of organics

Synthetic grey water was treated with a low-pressure gravity-driven membrane bioreactor (GDMBR) system. The system was operated without any direct shear at the membrane surface and without any cleaning or flushing. In order to reduce energy consumption, one reactor was operated without aeration and the results were compared with an aerated reactor. Although the dissolved oxygen content was low (0.4–0.6mg/L) in the non-aerated system, a stable permeability was observed at a level of around 20L/m2hbar (flux of 1L/m2h). The fouling resistance was dominated by the bio-fouling layer, which could be removed hydraulically. In comparison to the aerated system, the bio-fouling layer grown without aeration exhibited a lower biological activity, was thicker and had a lower surface roughness. Furthermore, the stable permeability of the aerated system was higher (40L/m2hbar), which could be explained by a lower content and load of extracellular polymeric substances (including extracellular polysaccharides and proteins). In comparison to filtration through a non-fouled membrane, the rejection of biopolymers and humic substances was strongly enhanced, which shows that the bio-fouling layer acts as a secondary membrane. The energy consumption was 0.02–0.04kWh/m3, which is substantially less than for normal MBRs, and even less than for the traditional activated sludge process. These results show that grey water can be treated in a membrane reactor without any cleaning and flushing and even without any aeration, which makes the process suitable for decentralized wastewater treatment and considerably reduces the energy consumption.

QAC modified PVDF membranes: Antibiofouling performance, mechanisms, and effects on microbial communities in an MBR treating municipal wastewater

Biofouling remains as a critical issue limiting the widespread applications of membrane bioreactors (MBRs). The use of antibiofouling membranes is an emerging method to tackle this issue. In this study, a polyvinylidene fluoride (PVDF) membrane was modified using a quaternary ammonium compound (QAC) to create an antibiofouling membrane. The membrane was used in an MBR and the performance, mechanisms, and effects on microbial communities of this membrane were compared to a control operated in parallel. Results showed that the membrane exhibited a significantly reduced transmembrane pressure increase rate of 0.29 kPa/d compared with 0.91 kPa/d of the control. Analysis using a confocal laser scanning microscope (CLSM) revealed almost complete lack of living microbes on the antibiofouling membrane in contrast to the control. However, specific oxygen uptake rate and dehydrogenase activity analyses demonstrated no adverse impacts on microbial viability of the bulk activated sludge. Bacterial population analysis using the Illumina Miseq platform added further evidence that the use of antibiofouling membrane did not exert negative influences on richness, diversity and structure of the bacterial community. Effluent quality of the test MBR also exhibited minimal difference from that of the control reactor. The amount of polysaccharides and proteins in the biofouling layer was also significantly reduced. Quartz crystal microbalance with dissipation monitoring suggested that the antibiofouling membrane only allowed organic matter with strong adhesion properties to attach onto the membrane surfaces. These findings highlight the potential of the antibiofouling membrane to be used in MBRs for wastewater treatment and reclamation.

Time-resolved monitoring of biofouling development on a flat sheet membrane using optical coherence tomography

Biofouling on a membrane leads to significant performance decrease in filtration processes. In this study, an optical coherence tomography (OCT) was used to perform a time-resolved analysis of dynamic biofouling development on a submerged membrane under continuous operation. A real-time change in the biofouling morphology was calculated through the image analysis of OCT scans. Three videos were generated through the acquisition of serial static images. This is the first study that displays the dynamic biofouling formation process as a video. The acquisition of OCT cross-sectional scans of the biofouling allowed to evaluate the time-lapsed evolution for three different time periods (early stage, double layers and long-term). Firstly, at the early filtration stage, membrane coverage and average biofouling layer thickness were found to be linearly correlated with the permeate flux pattern. Secondly, after 3 d of operation, an anomalous morphology was observed, constituted by a double-layered biofouling structure: denser on the bottom and looser on the top. In a long-term operation, the biofouling structure underwent a dynamic evolution over time, resulting in a multi-layered structure. The biofouling formation information was closely associated with filtration performance (i.e. flux) indicating the suitability of OCT as real-time and in-situ biofouling monitoring technique.

A low pressure gravity-driven membrane filtration (GDM) system for rainwater recycling: Flux stabilization and removal performance

Rainwater is a nature resource, which can be widely used for non-potable and potable applications in water scared countries after appropriate treatment. Gravity-driven membrane filtration (GDM) process is a promising technology for decentralized rainwater treatment due to no backwashing, flushing and chemical cleaning. In this study, we established a single lab-scale GDM system for the stored rainwater (simulative cellar rainwater) treatment with two months operation, and a stored tap water was used as a compared system to evaluate the permeability and organics removal performance. Results showed that GDM exhibited a good performance for bacteria and turbidity removals, but the removal performance of DOC was undesirable due to the low rejection of low molecular-weight fulvic. Additionally, the permeate flux reached stable with the value of 6–6.5 L/m2h during 60 days operation in the rainwater system, however, the tap water system stabilized only at 4 L/m2h. Hydraulically reversible resistance accounted for large proportions (90%) of the total resistance, which indicated that the flux could be recovered by simple physical flushing. The bio-fouling layer adhered on the membrane surface was characterized at the end of the filtration experiment. Higher bio-activity with lower EPS (polysaccharides and proteins) contents of the fouling layer were found in the rainwater system compared with the control system, which was the main reason for the higher flux. These results show that rainwater can be treated in a single GDM process with low maintenance, which makes the process suitable for decentralized water supply.

Revisiting interrelated effects of extracellular polysaccharides during biofouling of reverse osmosis membranes: Viscoelastic properties and biofilm enhanced osmotic pressure

In addition to the effect of extracellular polysaccharides on biofilms viscoelastic properties and their related integrity and cohesion, their presence in biofilms of RO membranes can affect biofilm porosity and associated electrolytes diffusion. In order to elucidate how polysaccharides can affect both biofilm viscoelasticity and back diffusion of electrolytes on RO membranes, three bacterial strains of Pseudomonas aeruginosa PAO1, differentially expressing the Psl polysaccharide, were used as biofouling agents. During the biofouling stage, similar permeate flux decline was observed for all strains, while elevation in salt passage was lower for the Psl-deletion mutant biofilm. After the biofilm washing stage, as shear rate was elevated, permeate flux recovery was significantly higher and a decrease in salt passage was evident, in the Psl-deletion mutant biofilm. In contrast, in Psl containing biofilms, an elevation in salt passage was evident after the washing stage. Salt passage results, CLSM analysis and the intrinsic mass transfer coefficient kd, provided us with an overall range of biofouling layer’s porosity between 0.25 and 0.35. Lastly, the higher amounts of biomass of Psl containing biofilms persisted on the RO membranes after the washing stage, corroborated with both EPS viscoelastic properties measured by QCM-D and biofilm elasticity measured by AFM. This study highlights mechanistically, the EPS effects on biofouling of RO membranes, mediated by biofilm mechanical properties as well as ion transport.

In-situ assessment of biofilm formation in submerged membrane system using optical coherence tomography and computational fluid dynamics

This paper introduces a novel approach to study the biofouling development on gravity driven submerged membrane bioreactor (SMBR). The on-line monitoring of biofilm formation on a flat sheet membrane was conducted non-destructively using optical coherence tomography (OCT), allowing the in-situ investigation of the biofilm structure for 43 d. The OCT enabled to obtain a time-lapse of biofilm development on the membrane under the continuous operation. Acquired real-time information on the biofilm structure related to the change in the flux profile confirming the successful monitoring of the dynamic evolution of the biofouling layer. Four different phases were observed linking the permeate flux with the change of biofilm morphology. In particular, a stable flux of 2.1±0.1L/m2h was achieved with the achievement of steady biofilm morphology after 30 d of operation. Biofilm descriptors, such as thickness, biofilm area, macro-porosity and roughness (absolute and relative), were calculated for each OCT acquired scans. Interestingly, relative roughness was correlated with the flux decrease. Furthermore, the precise biofilm morphology obtained from the OCT scans was used in computational fluid dynamics (CFD) simulation to better understand the role of biofilm structure on the filtration mechanism.