Fouling analysis of a tertiary submerged membrane bioreactor operated in dead-end mode at high-fluxes

Vera, Luisa; Cabrera, E; Díaz, Oliver; Sánchez, Rubén D.; Bohorque, Rafael A.; Rodríguez‐Sevilla, Juan

doi:10.1016/j.memsci.2015.06.014

Cited by 25 publications

(12 citation statements)

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“…Whilst the particle matrix within heterogeneous MBR systems, is regarded as too complex to be only described by discrete surface forces, a transition from limited to significant irreversible fouling was observed when cycle length increased from 9 to 14 mins, which corresponded to a critical mass (Equation 7) between 0.7 and 1.1 g MLSS m -2 at J 20 of 13.5 L m -2 h -1 . Vera et al [32] described reversibility of the deposit formed within the dead-end filtration cycle of an MBR to be also governed by cake compressibility, which we propose to be dependent upon the matrix composition and character. To illustrate, in this study, the critical mass was considerably lower than previously identified for MBR (4.6-4.8 g MLSS m -2 , J= 24 L m -2 h -1 ), which can be explained by the higher colloidal fraction within the AnMBR suspension as the SMP concentration (sum of protein and carbohydrate) ( Table 1) was around 5-7 times that in denitrification MBR [24,25].…”

Section: Discussionmentioning

confidence: 70%

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Identification of gas sparging regimes for granular anaerobic membrane bioreactor to enable energy neutral municipal wastewater treatment

Wang

Cingolani

Eusebi

et al. 2018

Journal of Membrane Science

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In this study, conventional and novel gas sparging regimes have been evaluated for a municipal wastewater granular anaerobic MBR to identify how best to achieve high sustainable fluxes whilst simultaneously conserving energy demand. Using continuous gas sparging in combination with continuous filtration, flux was strongly dependent upon shear rate, which imposed a considerable energy demand. Intermittent gas sparging was subsequently evaluated to reduce energy demand whilst delivering an analogous shear rate. For a flux of 5 L m-2 h-1 , a fouling rate below 1 mbar h-1 was sustained with low gas sparging frequency and gas sparging rates. However, to sustain low fouling rates for fluxes above 10 L m-2 h-1 , a gas sparging frequency of 50 % (i.e. 10 s on/10 s off) and an increase in gas sparging rate is needed, indicating the importance of shear rate and gas sparging frequency. An alternative gas sparging regime was subsequently tested in which filtration was conducted without gas sparging, followed by membrane relaxation for a short period coupled with gas sparging, to create a pseudo dead-end filtration cycle. Fouling characterisation evidenced considerable cake fouling rates of 200-250 mbar h-1 within each filtration cycle. However, long term fouling transient analysis demonstrated low residual fouling resistance, suggesting the cake formed during filtration was almost completely reversible, despite operating at a flux of 15 L m-2 h-1 , which was equivalent or higher than the critical flux of the suspension. It is therefore asserted that by operating filtration in the absence of shear, fouling is less dependent upon the preferential migration of the submicron particle fraction and is instead governed by the compressibility of the heterogeneous cake formed, which enables higher operational fluxes to be achieved. Comparison of energy demand for the three gas sparging regimes to the energy recovered from municipal wastewater AnMBR demonstrated that only by using dead-end filtration can energy neutral wastewater treatment be realised which is the ultimate ambition for the technology.

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Section: Discussionmentioning

confidence: 70%

“…According to the cake filtration model, the TMP can also be described through inclusion of suspension characteristics [32]:…”

Section: Anaerobic Mbr Pilot Plantmentioning

confidence: 99%

Identification of gas sparging regimes for granular anaerobic membrane bioreactor to enable energy neutral municipal wastewater treatment

Wang

Cingolani

Eusebi

et al. 2018

Journal of Membrane Science

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“…This indicated the potential for complete deposit reversibility under super-critical fluxes during both average flow and peak flow period in AnMBR. Whilst this study illustrates comparable performance to continuous gas sparging, further work is required to establish the potential to sustain higher initial fluxes and peak fluxes in AnMBR with pseudo dead-end filtration, in excess of the suspensions critical flux, which has been successfully demonstrated for other MBR applications [23,28,41]. It is therefore suggested that further capital cost reduction can be expected by increasing the attainable initial and peak flux through this pseudo dead-end filtration.…”

Section: Discussionmentioning

confidence: 83%

Sustaining membrane permeability during unsteady-state operation of anaerobic membrane bioreactors for municipal wastewater treatment following peak-flow

Wang

Jefferson

Soares

et al. 2018

Journal of Membrane Science

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Key highlights Peak flow characteristics (size, duration and frequency) are examined for AnMBR  Increasing gas flow rate during peak flow improves recovery  Supra-critical fluxes can be sustained for short durations  Specifying average flux below critical flux improves recoverability  Membrane area should be based on average flow, reducing capital cost AbstractIn this study, the impact of peak flow on anaerobic membrane bioreactor operation is investigated to establish how system perturbation induced by diurnal peaks and storm water flows will influence membrane permeability. Good permeability recovery was attained through increasing gas sparging during peak flow, which was explained by the transition in critical flux of the suspension at higher shear rates. However, supra-critical fluxes could also be sustained, provided peak flow was for a short duration. We suggest longer durations of supra-critical operation could be sustained through introduction of reactive fouling control strategies (e.g. TMP set-point control). An initial flux below the critical flux, prior to the introduction of peak flow, was advantageous to permeability recovery, suggesting membrane 'conditioning' is important in governing recoverability following peak flow. The importance of conditioning was confirmed through analysis of multiple peak flow events in which the loss of permeability following each peak-flow event was increasingly negligible, and can be ascribed to the arrival of a steady-state in membrane surface deposition. Whilst responding to peak flow with increased gas sparging has been shown effective, the energy demand is considerable, and as such a pseudo dead-end filtration strategy was also evaluated, which required only 0.04 kWh m -3 of energy for gas sparging. Comparison of both filtration modes identified comparable fouling rates, and the feasibility of a low energy gas sparging method for peak flow management that has successfully enabled supra-critical fluxes to be achieved over long-periods in other MBR applications. Importantly, membrane . Please refer to any applicable publisher terms of use.2 area provides the highest contribution toward capital cost of AnMBR. The potential to turnup flux in response to peak-flow has been identified in this study, which suggests membrane area can be specified based on average flow rather than peak flow, providing substantive reduction in the capital cost of AnMBR for municipal wastewater treatment.

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“…To save energy, MBRs can be operated without air scouring that leads to a reduction in the back‐transport (due to the lack of shear stress) and, consequently, deterioration of membrane filtration. In this case, the operation should be implemented at high fluxes to control membrane fouling by physical cleaning and increasing the backwashing efficiency . There are studies conducted by researchers in other literature that propose effective strategies to reduce the aeration demand during filtration processes .…”

Section: Membrane Foulingmentioning

confidence: 99%

Current Status and Future Prospects of Membrane Bioreactors (MBRs) and Fouling Phenomena: A Systematic Review

et al. 2018

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Membrane bioreactors (MBRs) have been widely used for municipal and industrial wastewater treatment around the world due to their advantages, which include higher efficiency, smaller footprint, and lower sludge production over other conventional activated sludge (CAS) processes. However, membrane fouling that results from physicochemical interactions between the membrane and the components of the mixed liquor still remains the most challenging matter preventing the broad application of MBR technology. Recently, a considerable number of experimental and modelling investigations have been conducted concerning MBRs and membrane fouling. Despite the development of low‐fouling membrane systems, more research and engineering activities with a focus on surface modification, wastewater specifications, pre‐treatment and treatment conditions, and efficient fouling control and remedy strategies are still needed to minimize the probability of the occurrence of fouling. It is vital to investigate important aspects of the characterization and mechanisms of the fouling phenomenon to find reliable and long‐term solutions. This review provides a detailed survey of the main aspects of the MBR processes, configurations, advantages and disadvantages, fouling phenomenon, and fouling control strategies in MBRs. Past research and engineering activities in this area are critically reviewed such that pros and cons of recent developments in fouling inhibition and mitigation approaches are also discussed. The main practical and theoretical challenges for the effective utilization of MBRs in various municipal and industrial sectors are then addressed. At the end, we offer useful practical guidelines and recommendations for the better design and operation of MBRs in industrial and public communities.

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Fouling analysis of a tertiary submerged membrane bioreactor operated in dead-end mode at high-fluxes

Cited by 25 publications

References 50 publications

Identification of gas sparging regimes for granular anaerobic membrane bioreactor to enable energy neutral municipal wastewater treatment

Identification of gas sparging regimes for granular anaerobic membrane bioreactor to enable energy neutral municipal wastewater treatment

Sustaining membrane permeability during unsteady-state operation of anaerobic membrane bioreactors for municipal wastewater treatment following peak-flow

Current Status and Future Prospects of Membrane Bioreactors (MBRs) and Fouling Phenomena: A Systematic Review

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