Comparative investigation on the impact of polymeric substances on membrane fouling during sub-critical and critical flux operation of a municipal membrane bioreactor

Soluble organic macromolecules are ubiquitous in activated sludge supernatant. For the operation of membrane bioreactors (MBR) this group of substances is considered as the dominant factor causing severe membrane fouling due to the concentration polarisation phenomenon. The well established critical flux concept for the characterisation of membrane bioreactor's operation limits is based on filtration data only. As there is an cause-and-effect relation between the partial retention of organic compounds and the limited flux according the critical flux concept the aim of this study was to draw a comparison between different permeate fluxes on the retention of organic macromolecules. Thus, a municipal pilot-scale MBR with three capillary hollow fibre membrane modules was operated in sub critical, critical and supercritical flux mode, respectively and the retention of macromolecules was quantified by size exclusion chromatography. Three permeate extraction pumps allow a simultaneous operation with different operational conditions for each membrane module and proved the crucial impact of permeate flux on the fouling rate. The interchange of these conditions gave evidence of an optimised start-up procedure for MBRs characterised by higher permeate fluxes. An increased flux causes both a higher retention of soluble macromolecules and subsequent a higher fouling rate.

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Enhanced Removal of Organic Pollutants and Reactive Dye in Polyethersulfone Submerged Membrane Bioreactor (PES-SMBR) for Textile Wastewater

Current World Environment ◽

10.12944/cwe.16.1.33 ◽

2021 ◽

Vol 16 (1) ◽

pp. 329-341

Author(s):

Tukaram P. Chavan ◽

Ganpat B. More ◽

Sanjaykumar R. Thorat

Keyword(s):

Membrane Fouling ◽

Membrane Bioreactor ◽

Textile Wastewater ◽

Pilot Scale ◽

Reactive Dye ◽

Hollow Fibre ◽

Flow Mode ◽

Permeate Flux ◽

Chemical Cleaning ◽

Submerged Membrane Bioreactor

The present investigation was carried out to assess the operation of a pilot-scale submerged membrane bioreactor (SMBR) for the treatment of reactive dye and textile wastewater. The operation of SMBR model was conducted by using a polyethersulfone (PES) hollow fibre membrane with continuous flow mode at different HRTs at 8, 6 and 4 h, for 90 days. During the entire operation, the average permeate flux, TMP, F/M ratio and OLR was found to be 19 (L/m²/h), 2.6 (psi), 0.10 (g BOD/(g MLSS•d) and 0.89 (kg BOD/m³.d), respectively. The variations in the permeate flux, TMP, F/M ratio and OLR have not adversely effects on the operation of the SMBR model. Throughout the entire operation, despite the TP, TDS and conductivity, the high amount of COD (82%), BOD (86%), NO3-N (79%), TSS (98%), turbidity (97%) and colour (79%), removal was achieved. The permeate flux was declined by membrane fouling and it was recovered by chemical cleaning as well as regular backwashing during the entire operation. The results obtained from the study concluded that the hollow fibre ultrafiltration polyethersulfone (PES) membrane shows good performance while treating textile wastewater along with reactive dye solution.

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Factors Affecting Reversible Pollution of Immersed Ultrafiltration Membrane in Treatment of Surface Water: Pilot Scale Studies

Water Practice & Technology ◽

10.2166/wpt.2010.069 ◽

2010 ◽

Vol 5 (3) ◽

Author(s):

Sun Lihua ◽

Li Xing ◽

Liu Ruiping ◽

Sun Wenpeng ◽

Li Guibai

Keyword(s):

Surface Water ◽

Membrane Fouling ◽

Polyvinylidene Fluoride ◽

Pilot Scale ◽

Ultrafiltration Membrane ◽

Permeate Flux ◽

Critical Flux ◽

Pvdf Membrane ◽

Factors Affecting ◽

Membrane Materials

The main factors (i.e., permeate flux, mixture characteristics, and membrane materials) affecting the pollution of immersed ultrafiltration membrane (immersed-UF) during the treatment of surface water were investigated through pilot scale studies. The variation of the running pressure was used as an indicator of membrane fouling. It is indicated that the rate of running pressure increased rapidly when the actual flux exceeded the critical flux, which exhibited to be 20 L·m−2·h−1 as for the membrane used in this study. The higher concentrations of turbidity and organic matter in the mixture contributed to the more significant increase of running pressure and the more serious membrane fouling. The higher temperature could lessen the membrane fouling to a certain extent. It was observed that membrane materials showed obvious effects on membrane fouling. The running pressure of Polyvinylidene Fluoride (PVDF) membrane was lower than that of chemically-modified Polyvinyl Chloride (PVC) at the same permeate flux, indicating the more promising potential of anti-pollution for PVDF membrane.

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Optimising the operation of a MBR pilot plant by quantitative analysis of the membrane fouling mechanism

Water Science & Technology ◽

10.2166/wst.2005.0617 ◽

2005 ◽

Vol 51 (6-7) ◽

pp. 19-25 ◽

Cited By ~ 62

Author(s):

T. Jiang ◽

M.D. Kennedy ◽

B.F. Guinzbourg ◽

P.A. Vanrolleghem ◽

J.C. Schippers

Keyword(s):

Membrane Fouling ◽

Pilot Plant ◽

Filter Cake ◽

Municipal Wastewater ◽

Hollow Fibre ◽

Critical Flux ◽

Membrane Pore ◽

Operational Conditions ◽

Temperature Conditions ◽

Filtration Flux

In order to optimize some operational conditions of MBR systems, a MBR pilot plant equipped with a submerged hollow fibre membrane module was employed in this study. The pilot MBR was fed with real municipal wastewater and the filtration flux, backwashing interval, aeration frequency and temperature were varied. A filtration flux below 25 l/m2h is generally recommended, at below this flux, the MBR operated at sub-critical flux conditions, the filter cake was minimized and membrane fouling was mainly attributed to the membrane pore blocking. Moreover, the membrane fouling, at below 25 l/m2h, was more reversible to backwashing; above this value, backwashing became less efficient to clean the membrane. Less frequent backwashing (e.g. 600 s filtration/45 s backwashing) decreased the amount of fouling irreversible to backwashing and its performance was superior to that of frequent backwashing (e.g. 200 s filtration/15 s backwashing). The MBR suffered more fouling at low temperature conditions (e.g. at 13–14 °C) than at high temperature conditions (e.g. at 17–18 °C). A conceptual model was built up and successfully interpreted this temperature effect.

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Correlation between membrane fouling and soluble/colloidal organic substances in membrane bioreactors for municipal wastewater treatment

Water Science & Technology ◽

10.2166/wst.2005.0615 ◽

2005 ◽

Vol 51 (6-7) ◽

pp. 1-8 ◽

Cited By ~ 77

Author(s):

B. Lesjean ◽

S. Rosenberger ◽

C. Laabs ◽

M. Jekel ◽

R. Gnirss ◽

...

Keyword(s):

Membrane Fouling ◽

Extracellular Polymeric Substances ◽

Municipal Wastewater ◽

Membrane Bioreactors ◽

Size Exclusion ◽

Water Phase ◽

Parallel Operation ◽

Municipal Wastewater Treatment ◽

Operational Conditions ◽

The Difference

Two similar membrane bioreactors of 2 m3 each were operated in parallel over two years under the same operational conditions, fed with the same municipal wastewater. The only process and operational difference between both pilot plants was the position of the denitrification zone (pre-denitrification in pilot 1 and post-denitrification in pilot 2). Despite parallel operation, the two MBRs exhibited different fouling rates and decreases in permeability. These differences could not be accounted for by MLSS concentrations, loading rates, or filtration flux. In a one-year investigation, soluble and colloidal organic material in the activated sludge of both MBR was regularly analysed by spectrophotometric and Size Exclusion Chromatography (SEC) methods. The larger organic molecules present in the sludge water phase (i.e. polysaccharides, proteins and organic colloids) originating from microbial activity (extracellular polymeric substances) were found to impact on the fouling and to explain the difference in membrane performance between the two MBR units. In both pilot plants, a linear relationship could be clearly demonstrated between the fouling rate of the membrane and the concentration of polysaccharides in the sludge water phase during a 5 month operational period at an SRT of 8 days.

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Recycling of Reverse Osmosis Concentrates to the Membrane Bioreactor in the MBR-RO Process for Water Reuse: effect on mbr performances

Revue des sciences de l eau ◽

10.7202/1040057ar ◽

2017 ◽

Vol 30 (1) ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Thi Thu Nga Vu ◽

Manon Montaner ◽

Christelle Guigui

Keyword(s):

Organic Matter ◽

Reverse Osmosis ◽

Membrane Fouling ◽

Water Reuse ◽

High Performance ◽

Membrane Bioreactor ◽

Membrane System ◽

Size Exclusion ◽

Ro Concentrate ◽

The Impact

Wastewater effluents can be treated by an integrated membrane system combining membrane bioreactor (MBR) and reverse osmosis (RO) for effective removal of micropollutants in the field of high-quality water reuse. However, discharging the RO concentrate waste stream directly into the natural environment could lead to serious problems due to the toxic components contained in the concentrates (micropollutants, salts, organic matter). A possible solution could be the recirculation of RO concentrate waste to the MBR. However, such an operation should be studied in detail since the recirculation of non-biodegradable organic matter or high concentrations of salts and micropollutants could directly or indirectly contribute to MBR membrane fouling and modification of the biodegradation activity. In this context, the work reported here focused on the recirculation of such concentrates in an MBR, paying specific attention to MBR membrane fouling. Lab-scale experiments were performed on a continuous MBR-RO treatment line with RO concentrate recirculation. The main goal was to determine the recovery of the RO unit and of the global process that maintained good process performance in terms of biodegradation and MBR fouling. The results demonstrate that the impact of the toxic flow on activated sludge depends on the recovery of the RO step but the same trends were observed regardless of the organic matter and salt contents of the concentrates: the concentration of proteins increased slightly. Size-exclusion high performance liquid chromatography (HPLC-SEC) was employed to study the effects of RO concentrate on the production of protein-like soluble microbial products (SMPs) and demonstrated a significant peak of protein-like substances corresponding to 10-100 kDa and 100-1 000 kDa molecules in the supernatant. Thus a significant increase in the propensity for sludge fouling was observed, which could be attributed to the increased quantity of protein-like substances. Finally, the effect of the concentrate on sludge activity was studied and no significant effect was observed on biodegradation, indicating that the return of the concentrate to the MBR could be a good alternative.

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A review on membrane applications and transport mechanisms in vacuum membrane distillation

Reviews in Chemical Engineering ◽

10.1515/revce-2016-0050 ◽

2017 ◽

Vol 34 (1) ◽

Cited By ~ 6

Author(s):

Rakesh Baghel ◽

Sushant Upadhyaya ◽

Kailash Singh ◽

Satyendra P. Chaurasia ◽

Akhilendra B. Gupta ◽

...

Keyword(s):

Membrane Fouling ◽

Membrane Separation ◽

Critical Evaluation ◽

Experimental Studies ◽

Membrane Distillation ◽

Permeate Flux ◽

Separation Processes ◽

Vacuum Membrane Distillation ◽

Polarization Coefficient ◽

The Impact

AbstractThe main aim of this article is to provide a state-of-the-art review of the experimental studies on vacuum membrane distillation (VMD) process. An introduction to the history of VMD is carried out along with the other membrane distillation configurations. Recent developments in process, characterization of membrane, module design, transport phenomena, and effect of operating parameters on permeate flux are discussed for VMD in detail. Several heat and mass transfer correlations obtained by various researchers for different VMD modules have been discussed. The impact of membrane fouling with its control in VMD is discussed in detail. In this paper, temperature polarization coefficient and concentration polarization coefficient are elaborated in detail. Integration of VMD with other membrane separation processes/industrial processes have been explained to improve the performance of the system and make it more energy efficient. A critical evaluation of the VMD literature is incorporated throughout this review.

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Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation

Water Science & Technology ◽

10.2166/wst.2008.111 ◽

2008 ◽

Vol 57 (4) ◽

pp. 601-605 ◽

Cited By ~ 2

Author(s):

Y. C. Su ◽

C. P. Huang ◽

H. C. Lee ◽

Jill R. Pan

Keyword(s):

Shear Stress ◽

Membrane Fouling ◽

Membrane Bioreactor ◽

Permeate Flux ◽

Membrane Unit ◽

Widespread Application ◽

Critical Flux ◽

Membrane Cleaning ◽

Close Link ◽

Novel Technologies

Recently, the membrane bioreactor (MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub-critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub-critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules (e.g. polysaccharides) may play an important role in membrane fouling under sub-critical flux operation.

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The role of shear conditions on floc characteristics and membrane fouling in coagulation/ultrafiltration hybrid process – the effect of flocculation duration and slow shear force

RSC Advances ◽

10.1039/c5ra18328f ◽

2016 ◽

Vol 6 (1) ◽

pp. 163-173 ◽

Cited By ~ 10

Author(s):

Jun Nan ◽

Meng Yao ◽

Qinggui Li ◽

Dan Zhan ◽

Ting Chen ◽

...

Keyword(s):

Membrane Fouling ◽

Shear Force ◽

Hybrid Process ◽

Permeate Flux ◽

Floc Characteristics ◽

The Impact

The impact of shear conditions during coagulation on the ultrafiltration permeate flux in a coagulation–ultrafiltration (C–UF) process was investigated.

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Application of Coagulation–Membrane Rotation to Improve Ultrafiltration Performance in Drinking Water Treatment

Membranes ◽

10.3390/membranes11080643 ◽

2021 ◽

Vol 11 (8) ◽

pp. 643

Author(s):

Hongjian Yu ◽

Weipeng Huang ◽

Huachen Liu ◽

Tian Li ◽

Nianping Chi ◽

...

Keyword(s):

Shear Stress ◽

Drinking Water ◽

Water Treatment ◽

Membrane Fouling ◽

Membrane Filtration ◽

Drinking Water Treatment ◽

Permeate Flux ◽

Organic Removal ◽

Cake Layer ◽

The Impact

The combination of conventional and advanced water treatment is now widely used in drinking water treatment. However, membrane fouling is still the main obstacle to extend its application. In this study, the impact of the combination of coagulation and ultrafiltration (UF) membrane rotation on both fouling control and organic removal of macro (sodium alginate, SA) and micro organic matters (tannic acid, TA) was studied comprehensively to evaluate its applicability in drinking water treatment. The results indicated that membrane rotation could generate shear stress and vortex, thus effectively reducing membrane fouling of both SA and TA solutions, especially for macro SA organics. With additional coagulation, the membrane fouling could be further reduced through the aggregation of mediate and macro organic substances into flocs and elimination by membrane retention. For example, with the membrane rotation speed of 60 r/min, the permeate flux increased by 90% and the organic removal by 35% in SA solution, with 40 mg/L coagulant dosage, with an additional 70% increase of flux and 5% increment of organic removal to 80% obtained. However, too much shear stress could intensify the potential of fiber breakage at the potting, destroying the flocs and resulting in the reduction of permeate flux and deterioration of effluent quality. Finally, the combination of coagulation and membrane rotation would lead to the shaking of the cake layer, which is beneficial for fouling mitigation and prolongation of membrane filtration lifetime. This study provides useful information on applying the combined process of conventional coagulation and the hydrodynamic shear force for drinking water treatment, which can be further explored in the future.

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Improvement of microfiltration performance in water treatment: is critical flux a viable solution?

Water Science & Technology ◽

10.2166/wst.2000.0669 ◽

2000 ◽

Vol 41 (10-11) ◽

pp. 309-315 ◽

Cited By ~ 5

Author(s):

S. Vigneswaran ◽

D.Y. Kwon ◽

H.H. Ngo ◽

J.Y. Hu

Keyword(s):

Membrane Fouling ◽

Particle Deposition ◽

Material Balance ◽

Transmembrane Pressure ◽

Operational Mode ◽

Permeate Flux ◽

Critical Flux ◽

Viable Solution ◽

Crossflow Microfiltration

In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.

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