Anaerobic Fluidized Membrane Bioreactor Research Articles

Evaluating performance of nano-Fe3O4 modified granular activated carbon assisted wastewater treatment in anaerobic fluidized membrane bioreactor

Magnetic granular activated carbon (MGAC), a nano-Fe3O4 modified granular activated carbon, was used as the carrier in an anaerobic fluidized-bed membrane bioreactor (AFMBR) to promote domestic wastewater treatment efficiency and alleviate membrane biofouling. Chemical oxygen demand (COD) removal reached 89 ± 2.6% with the effluent concentration of 20 ± 3.9 mg/L in the MGAC-AFMBR, while it was 28 ± 5.2 mg/L in AFMBR at hydraulic retention time (HRT) of 4 h. Total nitrogen (TN) removal was also enhanced by 4.0% with MGAC. An increased proportion of Chloroflexi and Bacteroidetes in the sludge may be responsible for improved treatment performance. MGAC reduced the protein and polysaccharide content in extracellular polymeric substances (EPS) by 9.8% and 8.1%, respectively. Besides, Bacteroidetes and Proteobacteria abundance decreased by 4.0% and 16.6% in the membrane cake layer with MGAC addition. Therefore, the high-quality effluent and low membrane biofouling of AFMBR was sustained by MGAC.

Effect of temperature variations in anaerobic fluidized membrane bioreactor: membrane fouling and microbial community dynamics assessment

A single-stage anaerobic fluidized membrane bioreactor (AnFMBR) was applied to investigate the effects of temperature changes on membrane fouling while treating real municipal wastewater. The AnFMBR was operated at four temperature phases: 25 °C for 42 days, 20 °C for 20 days, 15 °C for 15 days, and at 10 °C for 15 days. The systems achieved a total chemical oxygen demand (TCOD) removal efficiency of above 90% at all phases. As temperature decreased, accumulation of solids and possible incomplete hydrolysis led to an increase in TCOD and volatile fatty acids (VFAs) in the reactor. However, as temperature reduced to 10 °C, VFAs in the reactor reduced probably an indication of reactors adaptation. Total membrane filtration resistance gradually increased to 1.1 × 1011 m−1 from 2.1 × 1009 m−1 with a temperature decrease from 25 °C to 10 °C. This corresponded to a significant decrease in membrane permeability from 1.68 to 0.05 LMH/kpa. The protein fraction of the extracellular polymeric substances (EPS) was dominant in all phases, which was ascribed for significant membrane fouling causing permeability deterioration. Microbial richness and diversity analysis using next generation Ion torrent sequencing methods revealed that Proteobacteria phylum was most dominant at 25 °C, whereas Bacteroidetes, which are responsible for releasing proteinaceous EPS, were most dominant at low temperatures (15 °C and 10 °C), contributing to severe fouling. In conclusion, decrease in temperature did not affect the treatment efficiency but resulted in gradual increase in membrane fouling.

A novel anaerobic fluidized membrane bioreactor system: Improving process performance and fouling control

In this study, the effectiveness of a novel system of an anaerobic fluidized membrane bioreactor (AnFMBR) in treating wastewater was demonstrated and the results were validated by testing duplicate systems in parallel under similar operating conditions. In this novel system, an outer loop performs as an anaerobic reactor while an inner loop serves as an AnFMBR with granular activated carbon (GAC) used as a carrier and for fouling control. The GAC fluidization is restricted to the inner loop to minimize operational energy while ensuring membrane scouring. Fluidized GAC was a key factor in maintaining low TMP by attracting biofilm formation thus reducing attachment to the membrane surface and by removing deposits from membrane surface via abrasion. The new system improved fouling control as reflected in a slower buildup in transmembrane pressure (TMP) resulting in a 1.5 to 3.8 folds increase in typically reported operating periods for anaerobic membrane bioreactors (AnMBRs) and AnFMBRs. Similarly, energy requirements were estimated at 52 and 94% lower than those reported for typical AnMBRs and aerobic MBRs, respectively. At a validation level, both AnFMBR systems exhibited a similar performance with respect to several indicators including the microbial community composition, methane yield, chemical oxygen demand removal, TMP, and energy savings. • A novel AnFMBR system was tested for wastewater reuse and energy recovery. • Improved membrane fouling control with an increase in operating periods. • Energy requirements decreased by 52 to 94% relative to other MBRs studies. • Exoelectrogens population were abundant favoring methane production. • High reproducibility in duplicate systems was recorded in validating the results.

Fate and removal of emerging contaminants in anaerobic fluidized membrane bioreactor filled with thermoplastic gel as biofilm support

The Anaerobic Fluidized Membrane Bioreactor (AnFMBR) is a membrane–based hybrid technology that can overcome the limitations of conventional anaerobic sewage treatment. Although previous studies have demonstrated excellent performance in the removal of conventional organic pollutants, further research into the removal paths of emerging contaminants (ECs) under various operating conditions is required for proper design and development of the AnFMBR technology. Regarding this, the fate of four ECs in a lab-scale AnFMBR filled with thermoplastic gel for biofilm growth was investigated under various Hydraulic Retention Time (HRT) conditions. When the HRT was 13 h, diclofenac and 17β-estradiol were efficiently removed at 93% and 72% respectively. Even after an HRT reduction to 6.5 h, the system was still able to maintain high ECs removals (74% for diclofenac and 69% for 17β-estradiol). However, irrespective of HRT operational condition, smaller removals of 17a-ethinylestradiol (37–52%) were observed, while only marginal removals of amoxicillin were achieved (5–29%). Biotransformation was attributed as the main route for ECs removal. The results obtained in this study indicate that the membrane-based hybrid AnFMBR can be used to treat the target ECs without influence on anaerobic process. The technology had better removal efficiency for diclofenac and 17β-estradiol. However, the AnFMBR system exhibits high variability in EC removal and low capacity for amoxicillin removal, implying that a combination of other processes is still required to properly avoid the release of these contaminants into the environment.

Temperate climate energy-positive anaerobic secondary treatment of domestic wastewater at pilot-scale

Conventional aerobic secondary treatment of domestic wastewater is energy intensive. Here we report net energy positive operation of a pilot-scale anaerobic secondary treatment system in a temperate climate, with low levels of volatile solids for disposal (< 0.15 mgVSS/mgCODremoved) and hydraulic residence times as low as 5.3 h. This was accomplished with a second-generation staged anaerobic fluidized membrane bioreactor (SAF-MBR 2.0) consisting of a first-stage anaerobic fluidized bed reactor (AFBR) followed by a second-stage gas-sparged anaerobic membrane bioreactor (AnMBR). In stage 1, fluidized granular activated carbon (GAC) particles harbor methanogenic communities that convert soluble biodegradable COD into methane; in stage 2, submerged membranes produce system effluent (permeate) and retain particulate COD that can be hydrolyzed and/or recycled back to stage 1 for conversion to methane. An energy balance on SAF-MBR 2.0 (excluding energy from anaerobic digestion of primary suspended solids) indicated net energy positive operation (+ 0.11 kWh/m3), with energy recovery from produced methane (0.39 kWh electricity/m3 + 0.64 kWh heat/m3) exceeding energy consumption due to GAC fluidization (0.07 kWh electricity/m3) and gas sparging (0.20 kWh electricity/m3 at an optimal flux of 12.2 L/m2 h). Two factors dominated the operating expenses: energy requirements and recovery cleaning frequency; these factors were in turn affected by flux conditions, membrane fouling rate, and temperature. For optimization of expenses, the frequency of low-cost maintenance cleanings was adjusted to minimize recovery cleanings while maintaining optimal flux with low energy costs. An issue still to be resolved is the occurrence of ultrafine COD in membrane permeate that accounted for much of the total effluent COD.

Anaerobic membrane bioreactor model for design and prediction of domestic wastewater treatment process performance

Anaerobic treatment of municipal wastewater that produces energy and low levels of biosolids for disposal has the potential to replace conventional aerobic processes. Here we propose a generic model for anaerobic membrane bioreactors (AnMBRs) that incorporates hydrolysis and dispersed growth microbial metabolism of particulate and soluble substrates, including a size-exclusion constraint based upon the pore size of submerged membranes. The model can be expanded to include attached growth systems, such as anaerobic fluidized bed reactors (AFBRs) within the staged anaerobic fluidized membrane bioreactor (SAF-MBR) system. Model development entailed: (1) acquisition of key kinetic metabolic parameters based on independent batch studies, (2) creation of a matrix of metabolic processes, and (3) development of a model that describes the relevant mass balances in the system. The utility of the model is demonstrated for dynamic simulations of a pilot-scale second generation SAF-MBR treating municipal wastewater (SAF-MBR 2.0). System outputs include the COD of the system effluent (= permeate), recirculated bulk COD and MLSS, gas production rate and composition, and dissolved methane concentration. These parameters are critical for system design and assessment. Predictions of performance by a pilot-scale system agreed well with monitored values, typically with less than 10% error, indicating that the developed model and independent batch assays for model calibration can enable reliable systems-level performance simulations.

Coupling anaerobic fluidized membrane bioreactors with microbial electrolysis cells towards improved wastewater reuse and energy recovery

Anaerobic Membrane Bioreactors (AnMBRs) combine the advantages of anaerobic processes and MBR technology to improve effluent quality and energy recovery. However, these systems are associated with operational challenges such as membrane fouling and loss of dissolved methane that increases operation and energy expenses. In this study, a new configuration was developed combining AnMBRs with Microbial Electrolysis Cells (MECs). The effectiveness of the coupled AnFMBR-MEC system was tested by monitoring several indicators during the treatment of synthetic wastewater. The new configuration exhibited a 25-day shorter startup period, a 56% enhanced average methane yield, and a reduced membrane fouling with a maximum transmembrane pressure value nearly 6.5 folds lower than that exhibited by the AnFMBR alone. AnFMBR-MEC had an average CE of 40% and both reactors achieved around 90% COD removal. Similar bacterial communities existed in both reactors but with different relative abundance and localization. In the AnFMBR-MEC, the Direct Interspecies Electron Transfer was the likely dominant route for acetate consumption due to the abundance of Geobacter and Methanosarcina on the granular activated carbon and in suspension. The new system offers a promising technology with less fouling and improved resource recovery from wastewater due to the presence of different environmental niches (GAC, anode, cathode) for microbial colonization and growth, which resulted in the reduction of biomass in suspension and the proliferation of electroactive bacteria and methanogens as biofilms.

Process optimization and energy analysis of vacuum degasifier systems for the simultaneous removal of dissolved methane and hydrogen sulfide from anaerobically treated wastewater

The control of dissolved methane (CH4) and hydrogen sulfide (H2S) emissions in anaerobic effluents is essential for minimizing the environmental implications of greenhouse gases, odor, and carbon footprint, as well as for preventing energy loss in the form of unrecovered dissolved methane. This study assessed the feasibility of a vacuum degasifier for the removal of CH4 and H2S from staged anaerobic fluidized membrane bioreactor (SAF-MBR) effluent. The optimization results showed that the efficiency of the nozzle fitted degasifiers were superior to the media packed ones. In three-stage vacuum degasifiers at a −0.8 bar vacuum pressure, H2S removal was mostly pH dependent and 88% removal efficiency was achieved with an initial concentration of 13.6 mg/L. Methane removal was dependent primarily on the number of degasifier units, and approximately 94% efficiency was achieved in a three-stage degasifier. Energy balance analysis showed that energy production exceeded the system energy requirements with 0.05–0.07 kWh/m3 of surplus energy. These results provide deep insights into this new technology for simultaneous removal of dissolved CH4 and H2S, which can be referred for potential future applications.

Effects of sodium hypochlorite concentration on the methanogenic activity in an anaerobic fluidized membrane bioreactor

The effect of membrane cleaning chemical, NaOCl on specific acetoclastic methanogenic activity (SAMA) of biomass in the anaerobic fluidized membrane bioreactors (AFMBRs) was assessed. Granular activated carbon (GAC) was used as a fluidizing media in the AFMBR to provide membrane scouring effect and surface for biofilm attachment. Effect of NaOCl on methane production was negligible for GAC with biofilm (bGAC) samples up to 150 mg NaOCl/g VSS, but was significant for the bulk liquid samples with noticeable lag period over 300 h even at the dosage of 50 mg NaOCl/g VSS. The toxicity of NaOCl on methane production was reduced in samples with virgin GAC (vGAC) by allowing 14 days of biomass buildup period prior to NaOCl addition, although the vGAC alone did not alleviate the toxicity. The results revealed that NaOCl concentrations beyond 100 mg/L within the reactor inhibited methanogenic activity and the effects were more pronounced on suspended biomass than the immobilized biomass on GAC.

Removals of pharmaceuticals in municipal wastewater using a staged anaerobic fluidized membrane bioreactor

The staged anaerobic fluidized membrane bioreactor (SAFMBR) is effective to remove organic substances with reduced sludge production by minimizing excess waste sludge. This study investigated the removals of four pharmaceuticals present at trace levels in municipal wastewater by using a SAFMBR. The target pharmaceuticals included ibuprofen, naproxen, carbamazepine, and diclofenac. A pilot-scale SAFMBR with hydraulic retention times (HRTs) from 4.5 to 13.5 hr was established and operated for 450 days with a municipal wastewater spiked with four pharmaceuticals. In the results, the BOD and COD removals were effective and limitedly affected the presence of pharmaceuticals. The BOD removal efficiencies in the anaerobic fluidized membrane bioreactor (AFBR) and anaerobic fluidized membrane bioreactor (AFMBR) were 63.5 ± 28.6% and 81.6 ± 25.1%, respectively. However, the treatment efficiencies of four pharmaceuticals varied. Naproxen that contains electron donating group was treated efficiently (63.8%∼72.1%), whereas the removal efficiencies of ibuprofen (25.0%∼32.4%), carbamazepine (16.6–18.5%), and diclofenac (non-detected) remained low. Ibuprofen was less efficient to compete with other electron acceptors in an anaerobic environment. For pharmaceuticals such as carbamazepine with a high acid dissociation constant (pKa = 13.9) or diclofenac with a high octanol-water partition coefficient (log KOW = 4.51), sorption onto the sludge could be one critical process affecting their concentrations in the water phase. By being positively charged at neutral pH and/or hydrophobic, the pharmaceuticals were initially adsorbed onto sludge, followed by being desorbed when sludge decayed after long operating hours. Nitrogen balance was analyzed to indicate the decay of the bacteria in the AFMBR. Increasing the HRTs only slightly improved the treatment efficiencies (e.g., the naproxen removal was increased from 63.8% to 72.1% when the HRT was increased from 4.5 to 7.5 h). The different processes responsible for the removals of these pharmaceuticals were more critical and their effects were limitedly changed by HRT adjustment, indicating the importance of knowing the properties of a pharmaceutical for selection of a proper treatment approach.

Treatment of campus domestic wastewater using ambient-temperature anaerobic fluidized membrane bioreactors with zeolites as carriers

An anaerobic fluidized-bed bioreactor (AFBR) connected with an anaerobic fluidized membrane bioreactor (AFMBR) in series with natural zeolites as carriers was used to treat the campus domestic wastewater (chemical oxygen demand (COD) of 130 ± 38 mg/L) at ambient temperature (20–35 °C) in this study. Results indicate that the attached growth of anaerobic microbes was observed on the surface of zeolite and 95% of COD were removed in the AFBR after 30 days of batch operation. When the AFBR-AFMBR system was run with a HRT from 3 to 4 h, the COD, biochemical oxygen demand (BOD), and suspended solid (SS) were removed by 84, 87, and 96%, respectively, with the corresponding effluent COD, BOD, and SS of 20, 8, and 2 mg/L, respectively. Overall, 41% of the COD removal was attributed to coupling with sulfate reduction by sulfate-reducing bacteria in this study. In the AFMBR, the transmembrane pressure remained lower than 0.2 bar at the membrane flux of 10 L/m2-h. The membrane module was operated consecutively for 333 days without chemical cleaning. In addition, the maximum substrate utilization rate of 37 g/L-d determined based on the modified Stover-Kincannon equation elucidates that the organics in the campus domestic wastewater were readily biodegraded. This facilitated the AFBR-AFMBR system removing the organics to the levels lower than the discharging limits.

Pilot study of cold-rolling wastewater treatment using single-stage anaerobic fluidized membrane bioreactor

A pilot-scale single-stage anaerobic fluidized membrane bioreactor (AFMBR) was firstly used in this study to treat cold-rolling emulsion wastewater from steel industry. It was continuously operated for 302 days with influent COD concentration of 860–1120 mg/L. Under a hydraulic retention time of 1.5 d, the average effluent COD concentration of 72 mg/L achieved corresponding 90% of COD removal. The permeate flux was varied between 1.7 and 2.9 L/m2/h during operation which decreased with increased biomass concentration inside AFMBR. The trans-membrane pressure (TMP) was generally around 35–40 kPa, however, it increased up to 60 kPa when volatile suspended solid increased to above 2.5 g/L. Both flux and TMP data reveal the importance of biomass control for AFMBR operation. Results from terminal restriction fragment length polymorphism (T-RFLP) show the genus Methanosaeta was dominant on GAC and it shared dominance with the genera Methanomethylovorans and Methanosarcina in suspended sludge.

Biological acetate production from carbon dioxide by Acetobacterium woodii and Clostridium ljungdahlii: The effect of cell immobilization

This study investigated the acetate production from gas mixture of hydrogen (H2) and carbon dioxide (CO2) in the ratio of 7:3 using two acetogens: Acetobacterium woodii and Clostridium ljungdahlii. Batch result shows A. woodii performed two-phase degradation with the presence of glucose that lactate was produced from glucose and was reutilized for the production of butyrate and few acetate, while only acetate was detected when providing gas mixture. C. ljungdahlii produced butyrate and ethanol along with acetate when glucose was introduced, while only ethanol and acetate were found by feeding gas mixture. The acetate-to-ethanol (A/E) ratio can be enhanced by cell immobilization, while GAC immobilization produced only acetate and the production rate reached 0.072 mmol/d under fed-batch operation. Acetate production rate increased from 18 to 28 mmol/L/d with GAC immobilization when gas flowrate increased from 100 to 300 mL/min in anaerobic fluidized membrane bioreactor (AFMBR), and a highest A/E ratio of 30 implies the possible application of acetate recovery from H2 and CO2.

Single-stage versus two-stage anaerobic fluidized bed bioreactors in treating municipal wastewater: Performance, foulant characteristics, and microbial community

This study examined the receptive performance, membrane foulant characteristics, and microbial community in the single-stage and two-stage anaerobic fluidized membrane bioreactor (AFMBR) treating settled raw municipal wastewater with the aims to explore fouling mechanisms and microbial community structure in both systems. Both AFMBRs exhibited comparable organic removal efficiency and membrane performances. In the single-stage AFMBR, less soluble organic substances were removed through biosorption by GAC and biodegradation than those in the two-stage AFMBR. Compared to the two-stage AFMBR, the formation of cake layer was the main cause of the observed membrane fouling in the single-stage AFMBR at the same employed flux. The accumulation rate of the biopolymers was linearly correlated with the membrane fouling rate. In the chemical-cleaned foulants, humic acid-like substances and silicon were identified as the predominant organic and inorganic fouants respectively. As such, the fluidized GAC particles might not be effective in removing these substances from the membrane surfaces. High-throughout pyrosequencing analysis further revealed that beta-Proteobacteria were predominant members in both AFMBRs, which contributed to the development of biofilms on the fluidized GAC and membrane surfaces. However, it was also noted that the abundance of the identified dominant in the membrane surface-associated biofilm seemed to be related to the permeate flux and reactor configuration.

Development and application of a procedure for evaluating the long-term integrity of membranes for the anaerobic fluidized membrane bioreactor (AFMBR).

A bench-scale short-term test, developed to predict the long-term integrity of membranes with potential for use in anaerobic fluidized-bed membrane bioreactors, was used to evaluate several commercial hollow-fiber membranes. It was found that membrane performance varied widely, some membranes failing much more rapidly than others. Also found was that larger sizes of the fluidized media, in this case granular activated carbon (GAC), severely affected membrane structural integrity more than did smaller sizes, as did the method used for membrane attachment. Within the limits studied, the GAC packing ratio had only a minor impact. A decrease in membrane permeability that sometimes resulted during the testing and was caused by the deposition of fine GAC particles could be eliminated without membrane damage through simultaneous chemical cleaning and sonication. This new testing procedure should be useful for selecting membranes and reactor operating conditions to better ensure long-term operating performance of anaerobic fluidized-bed membrane bioreactors.

Performance of anaerobic fluidized membrane bioreactors using effluents of microbial fuel cells treating domestic wastewater

Anaerobic fluidized membrane bioreactors (AFMBRs) have been mainly developed as a post-treatment process to produce high quality effluent with very low energy consumption. The performance of an AFMBR was examined using the effluent from a microbial fuel cell (MFC) treating domestic wastewater, as a function of AFMBR hydraulic retention times (HRTs) and organic matter loading rates. The MFC–AFMBR achieved 89±3% removal of the chemical oxygen demand (COD), with an effluent of 36±6mg-COD/L over 112days operation. The AFMBR had very stable operation, with no significant changes in COD removal efficiencies, for HRTs ranging from 1.2 to 3.8h, although the effluent COD concentration increased with organic loading. Transmembrane pressure (TMP) was low, and could be maintained below 0.12bar through solids removal. This study proved that the AFMBR could be operated with a short HRT but a low COD loading rate was required to achieve low effluent COD.

Integrity of hollow-fiber membranes in a pilot-scale anaerobic fluidized membrane bioreactor (AFMBR) after two-years of operation

Abstract Membrane integrity was evaluated for a pilot scale anaerobic fluidized bed membrane bioreactor (AFMBR) after operation for 765 days. Permeability and bubble point tests results for membrane specimens taken from the top of the membrane modules were similar to those of virgin membranes, thus no significant membrane damage was found at the top. On the other hand, membrane specimens taken from the middle and bottom sections were damaged severely by the continuous contact with fluidized 0.8–4 mm granular activated carbon particles as evidenced through scanning electron microscopy, as well as by permeability and bubble point tests. The occurrence of such significant membrane damage after only 2 years of operation indicates that membranes with a higher resistance to abrasion are desirable for use in the AFMBR.

Anaerobic fluidized membrane bioreactor polishing of baffled reactor effluent during treatment of dilute wastewater

AbstractBACKGROUNDIn this study an anaerobic fluidized bed membrane bioreactor (AFMBR) is added as a second stage to an operating anaerobic baffled bioreactor (ABR) to form a staged anaerobic baffled‐fluidized membrane bioreactor (SAB‐FMBR) operating at ambient temperature.RESULTSThe ABR first stage was operated at 3 h hydraulic retention time (HRT) and was followed by the AFMBR operated at 0.93 to 1.16 h HRT. The SAB‐AFMBR system was fed with complex synthetic wastewater with COD averaging 250 mg L−1. GAC fluidization increased the critical flux of the AFMBR due to fouling reduction associated with the cleaning action of the GAC particles on membrane surfaces. However, sustainable flux for long‐term operation of the AFMBR was lower than the critical flux determined in short‐term tests. Overall COD removal by the SAB‐FMBR system when operating at a sustainable flux (8–9 L m−2 h−1) was 96% with effluent COD of about 11 mg L−1 and suspended solids concentration near zero. The electrical energy required for system operation in the AFMBR was 0.0087 kWh m−3, much less than that of an anaerobic MBR using biogas sparging to control membrane fouling.CONCLUSIONThe AFMBR was applied successfully as a second stage polishing system for an ABR treating complex synthetic wastewater at a temperature of 25 °C. © 2014 Society of Chemical Industry

Superior Removal of Disinfection Byproduct Precursors and Pharmaceuticals from Wastewater in a Staged Anaerobic Fluidized Membrane Bioreactor Compared to Activated Sludge

A recently developed, staged anaerobic fluidized membrane bioreactor (SAF-MBR) system has demonstrated performance comparable to that of conventional activated sludge systems at similar hydraulic residence times. The low biosolid generation rate, small footprint, and energy-positive potential (from captured methane) suggest the possible advantages of using the SAF-MBR upstream of advanced treatment for decentralized water reuse. Previous research conducted on laboratory-scale systems indicated that the SAF-MBR system is capable of removing pharmaceutical compounds. The purpose of this study was to compare the removals of disinfection byproduct precursors as well as pharmaceuticals by parallel pilot-scale SAF-MBR and full-scale aerobic systems treating municipal wastewater. Significantly better removals of antivirals (acyclovir and lamivudine), β-blockers (atenolol, metoprolol, and propranolol), a β-blocker aerobic biotransformation product (metoprolol acid), an anticonvulsant (carbamazepine), antibiotics ...

The potential roles of granular activated carbon in anaerobic fluidized membrane bioreactors: effect on membrane fouling and membrane integrity

This study examined the behavior of granular activated carbon (GAC) in a hybrid GAC-microfiltration process, which was used to simulate an anaerobic fluidized membrane bioreactor. GAC can exhibit two major beneficial roles in reducing membrane fouling, namely, (1) GAC scours the membranes to limit the cake layer formation and facilitate cake layer removal; (2) GAC tends to absorb potential foulants to reduce the interaction of foulants with the membranes. However, several detrimental effects of GAC on membrane performance were also observed. For example, (1) GAC appeared to release micro- and nanoscaled fine carbon particles, which can form potential foulants. (2) GAC abrasion can induce partial membrane integrity loss, which was proven by membrane permeability increase and microscopic autopsy. Interestingly, it was found that the GAC size had little influence on the scouring-enhanced filtration performance and scouring-induced membrane damage. The properties of the membrane materials were more important in determining the extent of integrity loss of the membrane after GAC abrasion. A membrane with good elongation properties (e.g. polyvinylidene fluoride) and GAC having a suitable size (i.e. less energy consumption) with good stability (i.e. releasing less fine carbon particles) is recommended for the hybrid fluidized GAC-membrane filtration process.