Blanket Process Research Articles

Investigating upflow anaerobic sludge blanket process to treat forward osmosis effluents of concentrated municipal wastewater under psychrophilic temperature

This work investigated the stability of the Upflow Anaerobic Sludge Blanket (UASB) reactor under psychrophilic temperatures with varying feed streams, simulating typical and concentrated sewage. In Phase I, treating municipal wastewater, chemical oxygen demand (COD) removal dropped from 77 ± 6 % to 41 ± 2 % as hydraulic retention time decreased from 24 to 12 h and organic loading rate (OLR) increased from 0.6 to 1.3 gCOD/(L∙d). In Phase II, at a similar OLR (≈1.2 gCOD/(L∙d)), the UASB treated organic-rich effluents (from 1.0 to 2.1 ± 0.1 gCOD/L) resulting from the pre-treatment of the forward osmosis (FO) process. The UASB performance improved significantly, achieving 87 ± 3 % COD removal and 63 ± 4 % methane recovery, with microbial analysis confirming methanogen growth. The COD mass balance showed up to 30 % more electrical energy recovery from sewage compared to conventional wastewater treatment plants (WWTPs), indicating that the FO-UASB combination is a promising approach to achieve energy-neutral operation in WWTPs.

Differential biotransformation of micropollutants in conventional activated sludge and up-flow anaerobic sludge blanket processes

We report differential micropollutant biotransformations in a conventional activated sludge (CAS) process and a pilot-scale up-flow anaerobic sludge blanket (UASB) process operating in parallel at the same wastewater treatment plant.

Assessing the effect of green tuff as a novel natural inorganic carrier on methane-producing activity of an anaerobic sludge microbiome

The upflow anaerobic sludge blanket (UASB) process is an anaerobic biological system that is widely used for the treatment of a variety of wastewater owing to its benefits such as low energy requirements and energy recovery as methane gas; however, unstable reactor performance is often observed. To solve this problem, several inert inorganic carriers and polymer materials have been studied for stabilization of the sludge microbial community and promotion of methane production. In this study, we demonstrate the effects of green tuff (GT) as a novel natural inorganic carrier on methane-producing activity (MPA) in combination with syntroph/methanogen-utilizable substrates and on the microbial community assembly of methanogenic batch cultures fed with granular sludge collected from UASB reactors treating milk- (MMW) or soy sauce- (SSW) manufacturing wastewater. The MPAs of MMW cultures with GT were 4.56- (propionate), 2.01- (n-butyrate), 1.37- (n-valerate), and 1.22- (benzoate) fold higher than those without GT. Likewise, SSW cultures with GT showed 1.34- (acetate) and 1.42- (propionate) fold higher MPA than those without GT. These results indicate that GT has potential to enhance MPAs during methanogenic degradation of these substrates. According to 16S rRNA transcripts-based community profiling, populations of syntrophic bacteria (Syntrophobacter and Smithella) and hydrogenotrophic methanogens (Methanobacterium and Methanolinea) in the cultures with GT were higher than in those without GT. Therefore, GT can be a potential solution for the activation of syntrophic partnerships and improvement/stabilization of reactor performance.

Stories of Welcome Blanket Makers: Towards a Philosophy of Craft

Welcome Blanket was created as a craftivism response to Trump’s call for a border wall. “Imagine if the massive distance of this wall was re-conceptualized and re-contextualized not to divide, but to include. Instead of a wall, a concrete line, to keep people out, what if lines of yarn became 3,500,640 yards of blankets to welcome people in?” The 3,200-blanket goal was quickly achieved and shown in the Smart Museum of Art at the University of Chicago. Then, with enclosed notes from the makers welcoming newly arrived immigrants, the blankets were distributed to refugees and immigrants in several resettlement communities throughout the United States. Meanwhile, members of a community associated with a nascent Makerspace in Norfolk, Connecticut, began making small (15”x 20”) “hugs” blankets for children who had been released from ICE detention centers to shelters. Welcome Blanket facilitated a process through their call to action to have these blankets, handmade dolls, and toiletries, distributed. We also sent a bale of blankets to the Heartland Alliance for a group of unaccompanied immigrant children coming into Chicago. We conducted a series of conversations with makers, ages nine to ninety, who were first-generation immigrants, children of immigrants, indentured servants, as well as people who did not know very much about their family’s immigrant experiences. These dialogues reveal much about the phenomenology of craft, the values that emerge in the context of community around craftivism, networks, and the spirit of co-creation. Drawing on hidden histories in what appears to be a homogenous community, makers found that through the action and reflection of the Welcome Blanket process, the community was able to weave together local concerns with global injustices. As Bruno Latour (2005) states: “Strength does not come from concentrations, purity and unity, but from dissemination, heterogeneity, and the careful plaiting of weak ties.”

Biogas recovery from fresh landfill leachates by using a coupled air stripping-up follow anaerobic sludge blanket (UASB) process

The present study focuses on fresh leachates treatment using anaerobic digestion. To overcome the unsuitable raw characteristics, appropriate pretreatment conditions were identified based on Batch tests. A subsequently optimized pretreatment-anaerobic two stages UASB coupled treatment was studied. The performance of the overall coupled treatment was assessed by monitoring volatile fatty acids (VFA), COD and ammonium removal, and biogas performance. Results showed that combining acidity correction to short aeration gives a synergetic effect and allowed appropriate anaerobic start-up conditions. Under continuous aerobic pretreatment-UASB digestion, significant removal of NH+4 (75.87%), COD (19.14%), and VFA (20.3%) were achieved during the aeration step resulting in the total abatement of 88.66%, 83.6% and 70.39% for NH+4, COD, and VFA, respectively. The process allowed good biogas performance up to 2,470 mL biogas/L and 123 mL CH4/gCOD removed, with gradual improvement from the first to the second UASB reactor. Inlet COD and VFA feeding rate seemed to be the main key parameters with 45.37 g COD/L.d and 18.43 g VFA/L.d as a critical threshold. Therefore, the anaerobic digestion of high COD leachates is highly feasible and the aerobic–anaerobic coupled treatment is a promising technical scenario that deserves further studies.

Influence of Pre-Hydrolysis on Sewage Treatment in an Up-Flow Anaerobic Sludge BLANKET (UASB) Reactor: A Review

The up-flow anaerobic sludge blanket (UASB) process has emerged as a promising high-rate anaerobic digestion technology for the treatment of low- to high-strength soluble and complex wastewaters. Sewage, a complex wastewater, contains 30–70% particulate chemical oxygen demand (CODP). These particulate organics degrade at a slower rate than the soluble organics found in sewage. Accumulation of non-degraded suspended solids can lead to a reduction of active biomass in the reactor and hence a deterioration in its performance in terms of acid accumulation and poor biogas production. Hydrolysis of the CODP in sewage prior to UASB reactor will ensure an increased organic loading rate and better UASB performance. While single-stage UASB reactors have been studied extensively, the two-phase full-scale treatment approach (i.e., a hydrolysis unit followed by an UASB reactor) has still not yet been commercialized worldwide. The concept of treating sewage containing particulate organics via a two-phase approach involves first hydrolyzing and acidifying the volatile suspended solids without losing carbon (as methane) in the first reactor and then treating the soluble sewage in the UASB reactor. This work reviews the available literature to outline critical findings related to the treatment of sewage with and without hydrolysis before the UASB reactor.

Preparation of High Sphericity Li<sub>2</sub>TiO<sub>3</sub> Tritium Breeder by Polymer Assisted Sedimentation Method

The tritium breeder materials used in solid tritium breeding blanket of fusion reactor are lithium-based ceramics, like lithium titanate (Li2TiO3), lithium orthosilicate (Li4SiO4), lithium aluminate（LiA1O2) and lithium zirconate (Li8ZrO6). Among them, Li2TiO3 has the advantages of stable chemical property, high mechanical strength and high lithium content, so it has become one of the preferred materials. Based on the design of solid blanket and tritium extraction process, breeder materials need to be made into a certain shape of pebbles. B Spherical breeder is widely used in the design of fusion reactor for the larger specific surface area, more channels between the pebbles to diffuse and release tritium, and easier loading or unloading. However, due to the high requirements of the breeder pebbles, the production control are not complete. In this paper, a new preparation method of ceramic pellets with high sphericity, polymer assisted sedimentation method, was used to prepare ceramic pebbles. The slurry consists of micro-scaled ceramic powder and organic monomers. Spherical droplets of ceramic slurry were obtained by sedimentation method in viscous liquids. The organic monomer contained in the droplets was heated to polymerize into small pellet preforms during the sedimentation process. By optimizing the sintering process, the fabricated pebbles could perform high compressive load (>18 N), spherical shape (0.95~1.02), uniform particle size (0.8~1.2mm) and porosity (15~20 %). The main advantages of this method is the mild preparation conditions (50~110 °C), the simplified transfer and purification process and convenient industrialization.. The obtained product has high spherical shape, uniform particle size, high compactness and mechanical strength.

Population Changes of Eubacteria, Sulfate-Reducing Bacteria and Methanogenic Archaea in an Anaerobic Reactor Processing Ethanol Distillery Vinasse

Abstract The microbiological characterization by molecular techniques (DGGE and quantitative PCR) of Archaea, Bacteria domain and sulfate-reducing bacteria (SRB) from a laboratory scale Up-flow Anaerobic Sludge Blanket (UASB) processing sugar cane vinasse was performed during the operational phase with increasing organic loads. The organic load removal efficiency was between 97% and 75% for volumetric organic loads (VOL) in the range of 0.6 to 15.4 kgCOD.m-3.d−1 and for higher VOL (until 27.0 kgCOD.m-3 .d−1) the removal efficiency decreased to 48%. Archaea represented the majority of the estimated population (107 copies of 16S RNA ribosomal gene. mL-1) followed by bacteria (106 copies of 16S RNA ribosomal gene. mL-1) and sulfate-reducing bacteria (SRB) (105 copies of dsrB gene. mL-1). There was a significant difference between the populations of Archaea and SRB with increasing VOL. DGGE profiles show differences among populations with increasing VOL, especially with respect to sulfate-reducing bacteria. The presence of SRB together with a high sulfate removal percentage (97%) of about 15 kgCOD.m-3d-1h, indicates the establishment of a sulfidogenic process.

Sludge blanket anaerobic baffled reactor for source-separated blackwater treatment.

The performance of a sludge blanket anaerobic baffled reactor was tested as an integrated treatment system for source-separated blackwater. The system consists of a stirred equalization tank, a buffer inlet tank, and two identical reactors, each with a working volume of 16.4 L, operated in parallel. Both reactors run at 3-days hydraulic retention time with different intermittent pulse feeding. Pulse lengths of 12 and 24 seconds per feed were set with respective rates of 114 L h-1 and 52 L h-1 for the short-pulse fed reactor (RI) and the long-pulse fed reactor (RII). Stable performance of the reactors was attained after 120 and 90 days, for RI and RII, respectively. After stable conditions attained, total chemical oxygen demand (COD) removal efficiency stabilized above 78%. Biogas production ranged from 0.52 to 1.16 L d-1 L-1 reactor volume, with 67-82% methane concentration and an average conversion of 0.69 ± 0.2 and 0.73 ± 0.2 g CH4-COD g-1CODin for RI and RII, respectively. The results imply that source-separated blackwater can be treated effectively in an anaerobic sludge blanket process on average loading rate of 2.3 ± 0.5 g COD d-1 L-1 reactor volume with high methane production potential and more than 80% removal of organic and particulate matter.

Environmental, Technical, and Economic Evaluation of a New Treatment for Wastewater from Slaughterhouses

The wastewater treatment has a fundamental role for all the industrial processes, being a crucial part in the water cycle. The meat industry around the world has severe problems associated with the huge freshwater requirements that increase with the population growth. However, nowadays, the most used slaughterhouse wastewater treatment (SWWT) system has negative environment impacts. Hence, the inclusion of the life cycle assessment method, as decision technique in the design and configuration of the treatment train for these industries, results in an attractive innovation. Particularly for the SWWT, the aerobic process is the most used approach; however, its high-energy requirements increase significantly the associated total cost. On the other hand, the upflow anaerobic sludge blanket process has been reported as an attractive treatment, but this needs a secondary treatment for achieving the environmental regulations for some pollutants. Therefore, this paper presents a techno-economic–environmental–social evaluation as a sustainable alternative in wastewater treatment train configuration based on the obtained results of the Trail and Refrigerator of the city of Morelia in Mexico. The results show that with the new configuration, the energetic requirement is reduced by 76%; thus, the operational cost is minimized in the same way, while the environmental impact is reduced by 30% with the integration of anaerobic and aerobic processes.

Impacts of biostimulation and bioaugmentation on the performance and microbial ecology in methanogenic reactors treating purified terephthalic acid wastewater

Up-flow anaerobic sludge blanket (UASB) processes treating purified terephthalic acid (PTA) wastewater often face challenges associated with biomass loss. As excessive biomass loss could lead to deterioration of PTA removal, biostimulation and bioaugmentation were often practiced without understanding the microbial impact in UASB. Three laboratory-scale UASB reactors were operated with synthetic PTA wastewater as the feed, with two added with co-substrate (glucose or molasses) on Day 170 for 90 days, and one with external granules on Day 118. Throughout the operation, treatment performance was measured together with the analysis of microbial communities of biomass samples using 16S rRNA-based gene Illumina sequencing. Glucose amendment destabilized both terephthalic acid and para-toluic acid removal, while molasses amendment improved para-toluic acid removal. Both substrate addition generally led to decreases in the abundances of syntrophs and methanogens and increases in carbohydrate-fermenting bacteria in the granular sludge. Regarding bioaugmentation, paper mill granule addition led to a temporary crash of terephthalic acid removal for 42 days, and deterioration of para-toluic acid removal throughout the operation. Syntrophs and methanogens were observed to colonize on the paper mill granules after three months, meanwhile growth of methanogens were stimulated on the PTA granules added initially. Overall, proper level of molasses amendment and external granule inoculation could be promising strategies to make up for biomass loss during the operation of PTA-degrading UASB.

Quality Assessment of Full-Scale Municipal Wastewater Treatment Plant Consisting UASB Reactors and Polishing Ponds During its Start-Up Phase in India

Amongst the technologies available, the up flow anaerobic sludge blanket (UASB) process has been one of the most widely applied methods for municipal waste water treatment especially in countries of warm climatic conditions like India. However, past about one decade has witnessed rapid decline in the UASB popularity and its implementation. There has been criticism from various sections on the performance of UASB reactors for not complying with the prescribed discharge standards. It is a general hypothesis that the UASB reactors are not meant for diluted waste water like municipal sewage when typically the BOD is less than 150 mg/l, COD 250 mg/l and sulphates are more than 150mg/l. An attempt has been made through this study to investigate the reasons on the basis of quality assessment and field observations on UASB reactors and it’s post-treatment of a newly commissioned (start-up) municipal (sewage) wastewater treatment plant commonly called ‘STP’ having capacity of 14 million litres per day (MLD). Study was aimed to know the gaps during the commissioning stage which could be related to poor removal efficiencies. This paper briefly discusses some issues related to operation and maintenance of the UASB plants with purpose for improvements.

Enhanced bioremoval of refractory compounds from dyeing wastewater using optimized sequential anaerobic/aerobic process

The upflow anaerobic sludge blanket process followed by the biological aerated filter process was employed to improve the removal of color and recalcitrant compounds from real dyeing wastewater. The highest removal efficiency for color was observed in the anaerobic process, at 8-h hydraulic retention time, seeded with the sludge granule. In the subsequent aerobic process packed with the microbe-immobilized polyethylene glycol media, the removal efficiency for chemical oxygen demand increased significantly to 75 %, regardless of the empty bed contact time. The average influent non-biodegradable soluble chemical oxygen demand was 517 mg/L, and the average concentration in effluent from the anaerobic reactor was 363 mg/L, suggesting the removal of some recalcitrant matters together with the degradable ones. The average non-biodegradable soluble chemical oxygen demand in effluent from the aerobic reactor was 87, 93, and 118 mg/L, with the removal efficiency of 76, 74, and 67 %, at 24-, 12-, and 8-h empty bed contact time, respectively. The combined anaerobic sludge blanket and aerobic cell-entrapped process was effective to remove the refractory compounds from real dyeing wastewater as well as in reducing organic loading to meet the effluent discharge limits. This integrated process is considered an effective and economical treatment technology for dyeing wastewater.

Congress OKs Hardship Exemption for Meaningful Use

For doctors unable to meet meaningful use requirements for 2015, Congress has approved a blanket process for those applying for a hardship exemption to avoid having a penalty applied to their Medicare payments in 2017.By voice vote in the House on Dec. 18 and a unanimous consent vote later that day in the Senate, Congress passed the Patient Access and Medicare Protection Act (S. 2425), which allows the Centers for Medicare & Medicaid Services to grant hardship exemptions globally, rather than on a case-by-case basis.There are a number of reasons a hardship exemption would be issued, including infrastructure-related problems, unforeseen circumstances, lack of face-to-face interactions, and lack of available certified electronic health records.Doctors seeking the exemption will need to apply by March 15, 2016; hospitals must do so by April 1, 2016.“Moving forward, this process will now allow doctors to avoid erroneous penalties that would have otherwise caused harm for patients seeking quality care,” Rep. Renee Ellmers (R-NC) said in a statement.Gregory Twatchman is a reporter with Frontline Medical News. For doctors unable to meet meaningful use requirements for 2015, Congress has approved a blanket process for those applying for a hardship exemption to avoid having a penalty applied to their Medicare payments in 2017. By voice vote in the House on Dec. 18 and a unanimous consent vote later that day in the Senate, Congress passed the Patient Access and Medicare Protection Act (S. 2425), which allows the Centers for Medicare & Medicaid Services to grant hardship exemptions globally, rather than on a case-by-case basis. There are a number of reasons a hardship exemption would be issued, including infrastructure-related problems, unforeseen circumstances, lack of face-to-face interactions, and lack of available certified electronic health records. Doctors seeking the exemption will need to apply by March 15, 2016; hospitals must do so by April 1, 2016. “Moving forward, this process will now allow doctors to avoid erroneous penalties that would have otherwise caused harm for patients seeking quality care,” Rep. Renee Ellmers (R-NC) said in a statement. Gregory Twatchman is a reporter with Frontline Medical News.

Sludge profiling at varied organic loadings and performance evaluation of UASB reactor treating sewage

An up-flow anaerobic sludge blanket (UASB) process was investigated for the treatment of domestic wastewater using a 60 l pilot scale reactor. The treatment performance was analysed at 8 h hydraulic retention time under ambient condition (8–40 °C). Biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) were used to evaluate the performance of organic matter and suspended solids removal. Specific methanogenic activity and solids concentration along the sludge bed height were determined to evaluate sludge quality. An average of 65–85% BOD, COD and TSS removal were achieved under different organic loadings 0.57–6.35 kg [COD] m −3 d −1 . The removal of organic matter showed a linear correlation with organic loads. The methanogenic activity decreased at lower organic loads. In addition, at low organic loads, high variations in COD reduction and low gas production were observed. • Long term performance of pilot-scale UASB reactor was investigated under ambient conditions. • Sludge bed profiles were determined at different organic loading and biogas production rates. • Specific methanogenic activity was investigated. • Experimental results were verified with sludge bed model.

Succession of microbial community and enhanced mechanism of a ZVI-based anaerobic granular sludge process treating chloronitrobenzenes wastewater

The combined zero-valent iron (ZVI) and upflow anaerobic sludge blanket (UASB) process is established for the treatment of chloronitrobenzenes (ClNBs) wastewater, and the succession of microbial community and its enhanced mechanism are investigated in the study. Results showed that compared with the control UASB (R1), the stable COD removal, ClNBs transformation, and dechlorination occurred in the combined system (R2) when operated at influent COD and 3,4-Dichloronitrobenzene (3,4-DClNB) loading rates of 4200–7700gm−3d−1 and 6.0–70.0gm−3d−1, and R2 had the better shock resistance and buffering capacity for the anaerobic acidification. The dechlorination for the intermediate products of p-chloroanaline (p-ClAn) to analine (AN) occurred in R2 reactor after 45 days, whereas it did not occur in R1 after a long-term operation. The novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed in the combined system, and higher microbial activities including ClNB transformation and H2/CH4 production were achieved simultaneously. The dominant bacteria were closely related to the groups of Megasphaera, Chloroflexi, and Clostridium, and the majority of archaea were correlated with the groups of Methanosarcinalesarchaeon, Methanosaetaconcilii, and Methanothrixsoehngenii, which are capable of reductively dechlorinating PCB, HCB, and TCE in anaerobic niche and EPS secretion.

Evaluation of performance in a combined UASB and aerobic contact oxidation process treating acrylic wastewater

The lab-scale and full-scale performance of a combined mesophilic up-flow anaerobic sludge blanket (UASB) and aerobic contact oxidation (ACO) process for treating acrylic wastewater was studied. During lab-scale experiment, the overwhelmed volumetric load for UASB was above 6 kg chemical oxygen demand (COD) ·(m−3·d−1) since COD removal efficiency dropped dramatically from 73% at 6 kg COD·(m−3·d−1) to 61% at 7 kg COD·(m−3·d−1) and 53% at 8 kg COD·(m−3·d−1). Further results showed that an up-flow fluid velocity of 0.5 m h−1 for UASB obtained a highest COD removal efficiency of 75%, and the optimum COD volumetric load for the corresponding ACO was 1.00 kg COD·(m−3·d−1). Based on the configuration of the lab-scale experiment, a full-scale application with an acrylic wastewater treatment capacity of 8 m3 h−1 was constructed and operated at a volumetric load of 5.5 kg COD·(m−3·d−1), an up-flow fluid velocity of 0.5 m h−1 for UASB and a volumetric load of 0.9 kg COD·(m−3·d−1) for ACO; and the final effluent COD was around 740 mg L−1. The results suggest that a combined UASB–ACO process is promising for treating acrylic wastewater.

Full Scale Evaluation on Anionic Polyacrylamide Applied in Ferric Flocs Sludge Treatment

The Polyacrylamide (PAM) is a frequently used flocculant for high concentration suspensions removal in water treatment characterized by the generation of large and dense flocs. In this paper, by using the anionic PAM as flocculant, a full-scale experimental study was carried out on flocculating ferric flocs sludge with pelleting flocculation blanket process under scale of 19~38 m3/h. The investigation aimed to optimum the dosage of the PAM and evaluate the application of the PAM in ferric flocs sludge treatment. The experimental results indicated that the increasing of PAM dosage could improve both outlet turbidity and thicken sludge concentration obviously, under the raw wastes concentration of 285~1022 mg/L, the system could achieve ideal operation effect with PAM dosage of 0.3~2.7 mg/L and treatment unit surface loading of 19~38 m3/m2·H. The investigation results also proved that there exists an approximately linear relationship between optimal PAM dosage and raw sludge concentration, that is, the increasing of raw sludge concentration would require synchronously rising of the optimal dosage. While the relationship between maximum surface loading and raw sludge concentration appeared negatively linear dependence, the maximum surface loading would decreased linearly with the increasing of inlet sludge concentration.

Full Scale Optimization of Flocs Blanket Process Applied in Ferric Flocs Sludge Treatment

The flocs blanket process is a traditional technology for high concentration suspensions removal. In this paper, by thickening ferric flocs sludge, the flocs blanket process was optimized with a scale of 19~38 m3/H to achieve more satisfied operational condition. Under the raw sludge concentration of 100~1200 mg/L, an increase in polymer dosage would improve outlet turbidity, the moderate mechanical agitating strength of 3 rpm could achieve best operational results. The experimental results also revealed an approximately linear relationship between raw water concentration and optimum PAM dosage, that is, the optimum dosage of PAM increased synchronously with the increasing raw sludge concentration. While the relationship between raw sludge concentration and maximum up-flow rate reflected negatively linear dependence, the maximum up-flow rate would decrease linearly with the increasing raw sludge concentration. The experimental results proved that the flocs blanket process could be applied to thicken the ferric flocs sludge as a highly efficient technology.

Advanced characterization of fouling in membrane coupled with upflow anaerobic sludge blanket process

In this study, an advanced process based on the use of ultrafiltration hollow fibre membranes immersed in the supernatant of an upflow anaerobic sludge blanket bioreactor (MUASB) and operated under low permeate flux was proposed. Process sustainability was assessed under different operating conditions: membranes were immersed either in the supernatant or in the biomass bulk and operated under various permeate fluxes. Additionally, temporal investigation was also proposed through the advanced characterization of fouling behaviour by systematic fractionation (based on level of reversibility) and analysis by liquid chromatography–organic carbon detector. Among the various suspended solids (SS) concentrations in supernatant (10, 25, 100, and 400 mg L−1) and in biomass bulk (6500 mg L−1), higher fouling levels were observed under low SS concentrations. However, more easily reversible fouling was obtained under MUASB conditions, demonstrating potential long-term sustainability. Results of long-term operation indicated that an increase of flux leads to larger amounts of SS participating in irreversible fouling and higher irreversibility. Temporal change in fouling characteristics revealed that the most easily removable fouling layer (i.e. cake), and its relative fraction of SS, were the two main factors impacting on the overall hydraulic performance. Additionally, the development of microbial population on the membrane surface was closely related to the proteins content and the overall hydraulic resistance. Polysaccharides and other dissolved organic matters (humic substances, building blocks, and low molecular weight compounds) presented low effect on membrane fouling.