Optimisation of dead-end filtration conditions for an immersed anoxic membrane bioreactor

McAdam, Ewan J.; Judd, Simon

doi:10.1016/j.memsci.2008.09.032

Cited by 26 publications

(14 citation statements)

References 27 publications

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“…The authors accounted for this by the considerably lower solids concentration developed within the membrane tank, which evidently limited cake layer growth at the membrane surface [9,22,23]. Using a UASB configured AnMBR, Martin-Garcia et al [5] undertook a preliminary investigation of an alternative gas sparging regime which comprised sequential filtration cycles without gas sparging, followed by a combination of backwash and gas sparging, to create a low energy pseudo dead-end (DE) filtration cycle [24]. The authors determined reasonable sustainable flux of 7 L m -2 h -1 despite undertaking filtration in the absence of shear, which considerably reduced the gas sparging requirement and corroborates findings of earlier investigation into pseudo dead-end (DE) filtration for MBR with low solids concentration [24,25].…”

Section: Introductionmentioning

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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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: Introductionmentioning

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: 84%

“…Continuous gas sparging was compared to an alternative hydrodynamic regime, in which filtration was conducted without gas sparging. Following a period of filtration (9 minutes), gas sparging was introduced for 1 minute together with membrane relaxation to create a pseudo dead-end filtration cycle [28]. Initial fluxes of 6 and 10 L m -2 h -1 were evaluated, with fluxes doubled in response to peak flow ( Figure 12).…”

Section: Alternative Hydrodynamic Conditionsmentioning

confidence: 99%

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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“…Besides the influence of C sources, the investigations focused on different types of denitrification (hydrogenotrophic [19,24], autotrophic [25], heterotrophic [25]), membrane bioreactor (MBR) configurations [16], carbon to nitrogen (C/N) ratio [15,[25][26][27], and the removal of pesticides [27]. Moreover, studies were carried out on hydraulic retention time [28][29][30], concentration of mixed liquor suspended solids (MLSSs) [15,16,30], mathematical modelling of MBR [31], optimisation of the energy demand [29], trihalomethane formation potential [11,21,28,30] and the inhibition of nitrite [10,19]. The first commercial-scale biological drinking water denitrification plant utilising hydrogen was introduced at Rasseln in Germany [19,24].…”

Section: Introductionmentioning

confidence: 99%

Nitrate Removal from Groundwater with Membrane Bioreactor

Simonič¹,

Goršek²,

Petrović³

2017

Nitrification and Denitrification

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The aim of this study is to model the denitrification process performed in a membrane bioreactor (MBR). The research was carried out using a modified Zenon ZeeWeed 10 MBR system. The membrane module consisted of submerged hollow-fibre membrane with a pore size of 0.04 µm and an active area of 0.93 m 2 . The concentration of nitrate in drinking water was (70 AE 2) mg/L NO 3 À . During the experiment, we maintained a constant concentration level of activated sludge at approximately 0.76 g/L under anoxic conditions. Sugar was added to the activated sludge as a source of carbon. The Monod kinetic parameters were estimated based on the experimental data numerical interpolation. Afterwards, a dynamic simulation with known parameters was carried out, and the time dependence of the substrate and biomass concentration was studied. We developed a model based on actual substrate outlet concentration. In addition, the time required to reach a steady state was estimated.

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Optimisation of dead-end filtration conditions for an immersed anoxic membrane bioreactor

Cited by 26 publications

References 27 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

Nitrate Removal from Groundwater with Membrane Bioreactor

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