High Cross-flow Velocity Research Articles

Biofouling control of a forward osmosis membrane during single-pass pre-concentration of wastewater

Pre-concentration of wastewater using a forward osmosis (FO) membrane prior to processing by an anaerobic digester can enhance biogas production. However, biofouling caused by microbes in wastewater remains a challenge. The study aimed to evaluate the efficacy of chloramination in mitigating the biofouling of an FO membrane during a single-pass concentration of primary wastewater effluent. Pre-disinfection at a chloramine dose of 22–121 mg/L successfully alleviated membrane fouling. Bacterial cell counts in the feed and concentrate showed that most of the bacterial cells in the wastewater were trapped on the membrane surface or spacer. The FO membrane surfaces in non-chloraminated/chloraminated systems were fully-covered by intact/damaged bacterial cells, respectively, indicating that chloramination effectively mitigated biofouling. However, due to high permeate-recovery and low cross-flow velocity in a single-pass concentration process, organic fouling on the membrane surface (and possibly on the interior wall of the membrane-pores) appeared to cause a gradual reduction in permeate-flux. This study demonstrated successful biofouling control using chloramination during a single-pass and high-recovery pre-concentration of primary wastewater effluent.

Nutrient-driven forward osmosis coupled with microalgae cultivation for energy efficient dewatering of microalgae

In this study, a new forward osmosis (FO) coupled with microalgae cultivation process was developed as a means of energy-efficient dewatering of microalgae, adopting a microalgal culture medium as a draw solution. In so doing, the energy-intensive regeneration of draw solution is omitted, and the resulting dilute solution of nutrients is directly reused as a culture medium. Process feasibility was proved by using glucose, a common carbon source for heterotrophic microalgae cultivation, as draw solute in dewatering the microalgal culture. When glucose and microalgal suspension were used as draw solution and feed solution, respectively, membrane orientation and cross-flow velocity (CFV) were found to have substantial impacts on dewatering performance of forward osmosis: compared to active layer-facing-draw solution orientation (AL-DS) and low cross-flow velocity, active layer-facing-feed solution orientation (AL-FS) and high cross-flow velocity were more effective at reducing reversible and irreversible fouling and thereby improving water flux. In comparison with sea salt, which is considered a conventional draw solute that does not require a regeneration step, glucose showed better dewatering performance due to its lower reverse solute flux (RSF), which caused flux decline due to loss of osmotic pressure difference and cake-enhanced concentration polarization (CECP) in fouling layer. The nutrient-driven forward osmosis process coupled with microalgae cultivation led to the production of highly concentrated biomass (roughly 120 g/L), supporting the idea that this novel approach can offer a promising low-energy alternative for microalgal dewatering.

Influence of Ozone Treatment on Ultrafiltration Performance and Nutrient Flow in a Membrane Based Nutrient Recovery Process from Anaerobic Digestate.

Membrane filtration of biological suspensions is frequently limited by fouling. This mechanism is well understood for ultrafiltration of activated sludge in membrane bioreactors. A rather young application of ultrafiltration is the recovery of nutrients from anaerobic digestates, e.g., from agricultural biogas plants. A process chain of solid/liquid separation, ultrafiltration, and reverse osmoses separates the digestate into different products: an organic N-P-fertilizer (solid digestate), a recirculate (UF retentate), a liquid N-K-fertilizer (RO retentate) and water. Despite the preceding particle removal, high crossflow velocities are required in the ultrafiltration step to overcome fouling. This leads to high operation costs of the ultrafiltration step and often limits the economical application of the complete process chain. In this study, under-stoichiometric ozone treatment of the ultrafiltration feed stream is investigated. Ozone treatment reduced the biopolymer concentration and apparent viscosity of different digestate centrates. Permeabilities of centrate treated with ozone were higher than without ozone treatment. In a laboratory test rig and in a pilot plant operated at the site of two full scale biogas plants, ultrafiltration flux could be improved by 50–80% by ozonation. Nutrient concentrations in the fertilizer products were not affected by ozone treatment.

Milk protein fractionation by custom-made prototypes of spiral-wound microfiltration membranes operated at extreme crossflow velocities

Compared to tubular membranes, spiral-wound membranes (SWM) cannot be operated at very high crossflow velocities due to mechanical instabilities of the module. We therefore applied a novel approach using custom-made microfiltration SWM modules to study the effects of crossflow velocities beyond the level currently applicable for commercial SWM. First, we used a modified industrial SWM (0.96 m) to measure flux and protein permeation spatially resolved within the limits of crossflow conditions applied in routine operation (maximum ΔpL of 1.3 bar). Secondly, we applied a short SWM (0.24 m) to assess the effect of extreme crossflow velocities with a corresponding ΔpL of up to 2.8 bar m−1. The goal was to investigate the effects of deposit formation reduced to the minimum, and thus, to measure the theoretically achievable improvement of flux and protein permeation even though this is currently not practicable. As key result, we found a critical crossflow velocity up to which a significant increase of protein mass flow could be achieved; beyond which, however, no further reduction in filtration resistance caused by deposit formation was observed. The filtration became independent of the transmembrane pressure. Based on these findings, more rigid modules could potentially improve the performance of SWM.

Impact of Hydrodynamics on the First Stages of Biofilm Formation in Forward Osmosis with Spacers.

Initial deposition of bacteria is a critical stage during biofilm formation and biofouling development in membrane systems used in the water industry. However, the effects of hydrodynamic conditions on spatiotemporal deposition patterns of bacteria during the initial stages of biofilm formation remain unclear. Large field epifluorescence microscopy enabled in situ and real-time tracking of Bacillus subtilis in a forward osmosis system with spacers during the first 4 h of biofilm formation. This study quantitatively compares the spatiotemporal deposition patterns between different hydrodynamic conditions: high and low permeate water flux (6 or 30 L m-2 h-1) as well as high and low crossflow velocity (1 or 14 cm s-1). Low crossflow velocity and high permeate water flux maximized bacterial attachment to the membrane surface, which was 60 times greater (6 × 103 cells mm-2) than at high crossflow velocity and low permeate water flux (<100 cells mm-2). Imaging at 30 s intervals revealed three phases (i.e., lag, exponential, and linear) in the development of deposition over time. Quantification of spatial deposition patterns showed that an increase in the ratio of permeate water flux to crossflow velocity led to a homogeneous deposition, while a decrease had the opposite effect. The insights of this research indicate that an appropriate choice of hydrodynamic conditions can minimize bacteria accumulation prior to biofilm formation in new and cleaned FO membrane systems treating water of high fouling propensity.

Membrane Bioreactor with External Side-Stream Membranes and High Cross Flow Velocity to Treat Municipal Wastewater

In this work, a pilot unit using side-stream MBR configuration was operated in BioFlow mode (i.e. no back pulse) and BioPulse mode (with intermittent back pulses) to treat municipal wastewater with relatively low MLSS. The results showed that the trans-membrane pressure (TMP) was less in the case of BioPulse over the whole period of system operation compared to that of BioFlow mode. However, the energy consumption per unit volume of permeated water is slightly higher in the case of BioFlow mode (3.4 kW.hr/m3) than that in the case of BioPulse mode (3.2 kW.hr/m3). Therefore, operation in BioPulse is preferable due to stable TMP caused by nearly fully recoverable fouling type, which results in lower chemical cleaning frequency. The MBR unit showed steady performance at a flux of 60 L/m2.hr. The system could achieve good water quality that satisfies Iraqi standards requirements for wastewater reuse or discharge to water resources

Athermal forward osmosis process for the concentration of liquid egg white: Process performance and improved physicochemical property of protein

The concentrated liquid egg white (LEW) by dewatering process displays the remarkable advantages. However, the concentration process was hindered by the high viscosity and heat sensitivity of LEW. Forward osmosis (FO) as an emerging membrane technology to concentrate LEW was evaluated for the first time in this study. The effects of process conditions on FO flux, fouling control, and product quality were investigated. The LEW can be concentrated up to about 2.1 folds by a single FO process. Flux decline (up to 80%) occurred during the process which was attributed to membrane fouling and dilution of draw solution. However, the membrane fouling could be mitigated by higher cross-flow velocity and the flux could be recovered up to 100% by osmotic backwash. There was no significant leakage of draw solutes and loss of protein in LEW during FO process. The concentration of LEW resulted in a promoted products quality.

Efficient degumming of crude canola oil using ultrafiltration membranes and bio-derived solvents

Vegetable oils derived from rapeseed and its genetic variant canola, are conventionally extracted from oilseeds by means of an organic solvent, typically hexane. Concerns regarding the toxicity of hexane have meant safer and more environmentally friendly solvents such as terpenes are becoming attractive. In this research, the degumming of canola oil/terpene mixtures using ultrafiltration is considered as a critical step in such an extraction process. Polysulfone (PSF) and polyethersulfone (PES) membranes were found to be ineffective in this application, as the oil appeared to cause swelling of the membrane structure. This meant that the original flux could not be restored after cleaning. Conversely, a ceramic membrane (MWCO 5 kDa) provided stable behaviour over several cycles of operation when cleaned with pure solvent at high cross-flow velocity at 40 °C. This membrane showed high phospholipid retention (95 ± 2%), although some oil was also retained (16 ± 3%). Cymene emerged as the most attractive of the three terpenes tested, with higher permeate flux and phospholipid rejection than limonene or pinene. Industrial relevanceWhile hexane has been traditionally used for oilseed extraction, toxicity concerns are likely to restrict its industrial use in the future. This article provides information to engineers and food scientists on the use of terpenes as an alternative solvent. In particular, the potential for ultrafiltration to be used in degumming of canola oil/terpene mixture is assessed. Our research shows that polymeric membranes are unlikely to be useful at scale in this application, as they are not readily cleaned for reuse. Conversely, a ceramic membrane of 5 kDa pore size provides the necessary rejection of phospholipids. There is some oil retention, that might require a downstream recovery step. The best results were obtained with cymene, suggesting this is a good target for industrial use.

Spinel-based ceramic membranes coupling solid sludge recycling with oily wastewater treatment

Highly efficient and economic treatment of wastewater sludges and wastewaters in one way is a challenging issue in the water treatment field. Herein we present a waste-to-resource strategy for rational fabrication of low–cost ceramic membranes, which simultaneously addresses the treatment of heavy metal-laden sludges and the separation of oil-in-water (O/W) emulsions. A thermal conversion mechanism is proposed for complicated reactions between simulated nickel-laden wastewater sludge and bauxite mineral. In addition to full stabilization and recycling of heavy metal wastewater sludges, rational tailoring of ceramic membrane structures can also be realized to achieve high water flux and favorable mechanical and surface properties. With rational structure design, the tailored spinel-based ceramic membranes exhibited high rejection and high flux (7473 LMH·bar−1) simultaneously for separation of oily wastewater, outperforming other reported state-of-the-art ceramic membranes. The membrane fouling mechanism revealed the dominance of cake layer formation at low cross flow velocities, while a combined model of cake layer formation and pore blocking dominated membrane fouling at high cross-flow velocities. The proposed strategy can be potentially extended toward design of functional ceramic membranes derived from other heavy metal wastewater sludges and for other water treatment applications.

Comparative study of nanofiltration membrane characterization devices of different dimension and configuration (cross flow and dead end)

Comparison of nanofiltration characterization data from literature is challenging due to different hydrodynamics and system designs, which affect membrane retention. In this study, stirred cell (SC), micro and macro cross flow systems (micro and macro CF) with different configuration were used to measure salt and organic tracer retention. Minimal concentration polarization conditions were applied in order to:1)evaluate comparability of the systems for characterization of membrane pore radius and molecular-weight-cut-off,2)understand the impact of system configuration and operation on mass transfer,3)compare salt retention at laboratory scale with the retention of spiral wound module.Results indicated that system dimension was the most important parameter to affect the mass transfer and the concentration of both salt and organic tracers on the membrane surface (Cm) in the macro CF system. Indeed, the higher channel length to width ratio of macro CF was related to reduced mass transfer and higher Cm. However, a comparability of the three systems was observed by operating at low flux (below 80 L/m2h) and higher cross flow velocity (above 0.4 m/s), where the lowest concentration polarization conditions were maintained. This is valid taking into account the variation of hydrodynamics (e.g. relation of Sherwood number and Reynolds range), which is intrinsically related to the different operation modes of dead end and cross flow. This study gives a novel contribution to improve the accuracy of membrane characterization methodologies and to identify suitable operative conditions for testing new membrane materials at small scale.

Nonplanar vortex-induced vibrations of cantilevered pipes conveying fluid subjected to loose constraints

In this paper, a theoretical model for vortex-induced vibrations (VIVs) of a cantilevered pipe conveying fluid subjected to loose constraints is proposed and analyzed. The unsteady hydrodynamic forces associated with the wake dynamics are modeled by two distributed van der Pol wake oscillators. Taking into account the coupling between the structure and fluid, the full nonlinear partial differential equations of the flexible pipe are derived by using Hamilton's principle. The nonlinear partial differential equations for the pipe and wake are further discretized by the aid of the Galerkin's technique, resulting in a set of ordinary differential equations. These ordinary differential equations are further numerically solved by using a fourth-order Runge-Kutta integration algorithm. Via varying the internal and cross-flow velocities, the derived high-dimensional reduced-order model displays some interesting dynamical behaviors of the coupled system. Phase portraits, bifurcation diagrams, Argand diagram and oscillation shape diagrams are plotted, showing the existence of lock-in phenomenon and figure-of-eight trajectory. When the internal fluid velocity is small and below the critical value for flutter instability, the oscillation of the pipe is mainly induced by the cross flow. For internal flow velocity beyond the critical value for flutter instability, interestingly, the effect of low cross-flow velocity is not pronounced. For relatively high cross-flow velocity, both internal and external fluid flows can significantly contribute to the responses of the pipe. This work is expected to be useful for predicting the responses of marine oil-conveying pipes under the combined effects of internal and external fluid flows.

In Situ Visualization of Concentration Polarization during Membrane Ultrafiltration Using Microscopic Laser-Induced Fluorescence.

A novel noninvasive technique-microscopic laser-induced fluorescence (micro-LIF)-has been applied to achieve in situ visualization of concentration polarization (CP) of nanoparticles during cross-flow ultrafiltration at high resolutions. The reversible, highly dynamic nature of CP and its sensitive response to the filtration conditions were investigated and validated by direct visualization of the CP layer and the well depicted concentration profile near the membrane surface. Using micro-LIF, the formation of a CP layer during filtration and its back-diffusion after the filtration ceased can be directly observed. The dynamic variation of the CP layer with the cross-flow velocity and transmembrane pressure (TMP) change has also been demonstrated. The results showed that CP reached the steady state approximately 1 min after the filtration condition change. A higher cross-flow velocity and/or a lower TMP decrease the CP concentration and thickness. Further quantitative analysis of the filtration test results using the film theory model helps to obtain the particle concentration at the membrane surface and the thickness of the CP layer (30-50 μm). Accordingly, the nature of CP dynamics was characterized and the deficiency of the traditional CP model was explored.

Turbulent jet-assisted microfiltration for energy efficient harvesting of microalgae

For energy-efficient harvesting of microalgae using a hollow fiber membrane, a turbulent jet was implemented to induce local high crossflow velocity near the membrane surface for fouling reduction during microfiltration. The performance of the turbulent jet-assisted module was evaluated and compared to that of a control group that represented other types of flow conditions including the conventional-type hollow fiber membrane module. When assisted by the turbulent jet, permeate flux at the steady-state increased by 126% and the specific energy for filtrating out a unit volume of permeate was reduced by 38% relative to the conventional type. In the results of a computational fluid dynamics analysis, the wall jet created after impingement of the jet flew along the membrane surface with a reduced boundary layer, and it is expected that this provided a scouring phenomenon. Shear stress on the membrane surface increased 3.7-fold on average, and was highest at the point of impingement. With regard to energy efficiency, concentrating on increasing the local fluid velocity near the membrane via turbulent jets rather than increasing the entire feed recirculation is more practical to improve the filtration performance for microalgae harvesting with low power consumption.

The relationship between size-segregated particles migration phenomenon and combined membrane fouling in ultrafiltration processes: The significance of shear stress

Shear stress generated by cross flow velocity (CFV) was employed to investigate the migration of particles with varied sizes ranging from 0.5 µm to 100 µm in a laboratory flat sheet cell, which was implemented to investigate particle size segregation during the formation of combined membrane fouling. Computational fluid dynamic simulations of shear stress on the membrane surface over a range of CFV indicated that the peak value of shear stress (0.95–5.17 Pa) and average shear stress (0.267–1.873 Pa) all increased as the CFV increased (0.05–0.30 m/s). In case of the combine membrane fouling formed under short-term (6 h) filtration of mixed solution, the particle size segregation caused by shear stress was demonstrated using a laser scattering particle analyzer. In details, the volume fraction of small particles within cake layer was larger compared to that in the initial solution, whereas the large particles were susceptible to remain in the end solution. Under lower CFV, increasing shear stress could mitigate combined membrane fouling caused by organic matter and inorganic particles, however, under high CFV, increasing shear stress could enhance combined fouling, and the main reason was that higher shear stress increased the lift force exerted on particles, which could help large particles moving away from the membrane surface, leading to small particles depositing on the membrane surface and causing a severe membrane fouling. The implication is that the option of suitable hydrodynamic condition is preferable to reduce membrane fouling of mixed solution in the field of water treatment.

Critical flux and fouling mechanism in cross flow microfiltration of oil emulsion: Effect of viscosity and bidispersity

Membrane-based filtration is promising for applications in the food industry, for example, for processing dairy products, but membrane fouling restricts the efficiency of the process. The deposition of the main constituents in skim milk of casein, lactose and milk fat globules onto the membrane due to the permeate drag is inevitable, which necessitates a mechanistic study of the fouling phenomena. The Direct Observation through the Membrane (DOTM) technique was used to understand the effects of viscosity and bidispersity on the microfiltration of oil emulsions. Deposits at the feed-membrane interface clearly slowed down as the feed viscosity increased. The higher drag to the crossflow as a result of the higher viscosity caused more oil droplets to foul the membrane. However, although both casein and lactose increased the feed and permeate viscosity, the presence of lactose did not alter the fouling phenomena of a moving cake layer of oil droplets much, but the presence of casein caused the oil droplets to deposit instead as clusters. For casein, other than the viscosity effect, it also resulted in a bidisperse suspension, with the smaller particulates promoting membrane fouling. Agreement between the experimental data and the shear-induced diffusion model was good at the lower cross-flow velocities (CFVs) but poorer at higher CFVs, which indicate that the effect of viscosity appeared negligible at the lower CFVs but more dominant at the higher CFVs. The DLVO model agreed with the Jcrit and TMP results. This study sheds light on the membrane fouling phenomena for viscous feeds, and are expected to be useful particularly for food applications.

A model for rising bubbles interacting with crossflowing liquid

The effect of liquid crossflow on the behaviour of submerged bubbles was examined using a theoretical time-varying model based on the equations of motion in two-dimensional space. The results were compared with experimental rise velocities and previously obtained trajectories. Bubble images were recorded using high-speed photography at gas flow rates of 2–25 L/min and crossflow velocities of 0.059–0.334 m/s, respectively. Image processing was then used to measure the bubble rise velocities. Increasing the crossflows strongly limits the bubble rise velocities, which depend on the bubble size, especially at high crossflow velocities. The model's predicted velocities show good agreement with the experimental data, which had uncertainties of around ±10%. The model predicted nearly linear trajectories, which were visually similar to the experimental trajectories. We compared the model's trajectories with swarm centroids and predictions by an empirical correlation developed earlier for the swarm inclination angle. The model's results compared favourably with the experiments, although there were slight overpredictions, especially at high crossflows. This could be corrected in future works by developing more appropriate closure relationships related to crossflows.

Influence of high shear rate on particles size, rheological behavior and fouling propensity of fruit juices during crossflow microfiltration: Case of orange juice

Abstract This work aimed to characterize the impact of high shear rate generated by crossflow microfiltration on the particles size, the rheological behavior and the overall fouling propensity of fruit juices. To this end, two orange juices, with different characteristics, were circulated during a defined duration (until 120 min) under a high shear rate (22,270 s−1) in a side-stream membrane unit, without filtration. Results showed that this shearing condition was likely to induce significant changes concerning at the same time the particles size distribution (with a possible particles fractionation) and the rheological properties of the fruit juices (with a potential increase of energy of cohesion between the particles). The fouling propensity of the juices, estimated through lab-scale filtration test, was also modified by the shear rate, showing that new foulant components could be released during the circulation in the filtration loop. Industrial relevance Crossflow microfiltration is successfully applied to stabilize and clarify fruit juices or to concentrate their pulpy fraction. This work aimed to characterize for the first time the impact of high shear rate applied during crossflow microfiltration on the particles size distribution, the rheological behavior and the overall fouling propensity of fruit juices. This work showed for the first time that it is important to consider the impact of high shear rates on the particles size fractionation and the release of foulant compounds when carrying-out fruit juices microfiltration under high crossflow velocities. Crossflow microfiltration of fruit juices under high crossflow velocity may not be, in some cases, the most appropriate strategy to reduce membrane fouling. According to the juice characteristics, specific industrial strategies such as enzymatic treatment or mechanical actions (e.g. back-pulsing) would be more useful than crossflow velocity to enhance the overall performance of microfiltration.

Experimental study on impingement spray and near-field spray characteristics under high-pressure cross-flow conditions

The fuel spray injected into a direct injection (DI) engine is substantially affected by both the in-cylinder air flow and the piston cavity wall impingement. The combined effect of the air flow and the wall impingement plays an important role on the spray development, mixture formation, and subsequent combustion. In this study, the effects of cross-flow and flat wall impingement on the spray development and dispersion were investigated. The spray was injected by a valve covered orifice (VCO) nozzle under various cross-flow velocities and ambient pressures. Impingement spray images in a vertical plane and several horizontal planes were obtained by a high speed video camera and a continuous wave laser sheet. A high speed video camera connected with a long-distance microscope was employed to obtain the near-field spray images. The results show that cross-flow favors spray dispersion while the high ambient pressure tends to compress the spray profiles. Additionally, under an approximate liquid-to-air momentum flux ratio q, when the ambient pressure and cross-flow velocity were varied, at 2 ms ASOI the outlines of the spray in the windward side agree well, whereas the spray extended further in the leeward side at a lower ambient pressure. At the plane of y = 25 mm, a complex vortex movement was observed that resulted in a non-uniform distribution of droplets in the upper part of the spray in the leeward side. In addition, at the plane of y = 45 mm, an empty belt area occurred in the vortex core region revealing that the density of the droplets in this region was quite low. The quantitative analysis shows that with increasing cross-flow velocity, the spray tip penetration decreases slightly before impingement while the spray tip penetrates further on the wall surface after impingement. The high cross-flow velocity favors the spray breakup and dispersion leading to a larger wall-jet vortex while the high ambient pressure restrains the spray dispersion leading to a smaller spray tip penetration and vortex height. For near-field spray, the spray image at higher ambient pressure shows fewer ligaments. With increasing cross-flow velocity, the whole spray shifted downstream. The spray outline was wider at the initial stage (0.05 ms ASOI) than that at steady stage (2 ms ASOI) of spray evolution.

Physical cleaning techniques to control fouling during the pre-concentration of high suspended-solid content solutions for resource recovery by forward osmosis

The fouling propensity of digested sludge centrate, and the effectiveness of membrane flushing, air-scouring, and ultrasonication for physical cleaning were systematically evaluated. Accelerated fouling conditions were applied to simulate the long-term and intensive pre-concentration scenario that is required for phosphorus recovery from digested sludge centrate. The results suggest that membrane fouling during forward osmosis operation to pre-concentrate digested sludge centrate is mostly due to the deposition of small mineral crystals and particulate matter on the membrane surface. Both high cross-flow velocity flushing and ultrasonication were effective at preventing membrane fouling under accelerated fouling conditions. Our results also highlight the potential of intermittent membrane cleaning for achieving a higher cumulative permeate volume and lower energy consumption in comparison to continuous application to prevent membrane fouling. Among several physical cleaning regimes investigated in this study, the combination of ultrasonication and high cross-flow velocity flushing was the most effective and could maintain stable FO operation over several consecutive cleaning cycles.

Effect of the high cross flow velocity on performance of a pilot-scale anaerobic membrane bioreactor for treating antibiotic solvent wastewater

The effect of high cross flow velocity (CFV) on the operational efficiency of a pilot-scale anaerobic membrane bioreactor (AnMBR) treating antibiotic solvent effluents was explored. The average of total Chemical Oxygen Demand (COD) and tetrahydrofuran (THF) removal efficiencies during four Runs were 96.5% and 98.7%. Meanwhile, biological removal contributions were 74.3% and 78%, the rest part was attributed by the physical removal process of the membrane block, VFA (Volatile Fatty Acids) and alpha value (VFA/alkalinity) increased with the increase of CFV, resulted alkalinity decreased. Biomass concentration mixed liquid suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) as well as the polysaccharide increased smoothly in the suspended sludge with the CFV increasing, and the protein content decreased gradually. However, the concentration of biomass, polysaccharide and protein presented opposite trends in the attached sludge of the membrane. The results indicated that AnMBR can effectively treat the antibiotic solvent wastewater under high CFV.