Wastewater Treatment in Membrane Bioreactors: The Use of Polyelectrolytes to Control Membrane Fouling

Gkotsis, Petros; Peleka, Effrosyni; Zamboulis, D.; Mitrakas, Manassis; Tolkou, Athanasia K.; Zouboulis, Anastasios

doi:10.1007/s40710-016-0168-9

Cited by 10 publications

(5 citation statements)

References 25 publications

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“…Understanding the transport of charged macromolecules is important for protein diffusion, drug delivery, , pharmaceutical and separation processes, − and many more applications. Specifically, for separation processes, flexible polymers are known to foul membranes , and charged polymers have been used to mediate that fouling. , Membranes can also have different surface charges and the electrostatic interactions between the polyelectrolyte and membrane charge can play a key role in fouling . Thus, understanding the dynamics of polyelectrolytes in confinement can potentially reduce membrane interactions and improve separation processes.…”

Section: Introductionmentioning

confidence: 99%

Effect of Salt Concentration on Sodium Polyacrylate Diffusion in Convex Lens-induced Confinement (CLiC)

Roopnarine,

Morozova

2024

Macromolecules

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Membrane charge can influence how polyelectrolytes pass through pores in a separation process. In solution, polyelectrolyte dynamics have been studied extensively with dynamic light scattering. The behavior is heavily influenced by the ionic strength of the solution. Particularly at low ionic strengths, polyelectrolytes demonstrate two diffusion modes: a “fast” mode, attributed to counterion concentration fluctuations, and a “slow” mode believed to stem from the formation of aggregates caused by dipole–dipole interactions. To determine how this anomalous polyelectrolyte diffusion is affected by charged pores, we have examined the dynamics of fluorescently tagged, negatively charged sodium polyacrylate (NaPA) near similarly charged glass surfaces in convex lens-induced confinement. Differential dynamic microscopy (DDM) is used to determine the diffusion coefficient of NaPA in 150, 50, 10, and 1 mM ionic strength solutions. Our findings demonstrate a shift toward slower diffusion rates at salt concentrations below 50 mM, consistent with chain stretching. Interestingly, the “slow” and “fast” modes are not observed by using DDM in these geometries. However, in 1 mM ionic strength solutions, as the pore size reaches ∼0.30 μm, NaPA begins to visibly aggregate and even bind to the negatively charged surfaces. The free energy of the pore also shifts from repulsive to attractive at this salt concentration. These insights can further contribute to understanding polyelectrolyte solutions, both in bulk and near like-charged surfaces, due to changes in ionic strength.

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Section: Introductionmentioning

confidence: 99%

Effect of Salt Concentration on Sodium Polyacrylate Diffusion in Convex Lens-induced Confinement (CLiC)

Roopnarine,

Morozova

2024

Macromolecules

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“…These operational parameters can alter microorganism properties and help in optimizing the system’s performance. Recent studies have depicted that disk rotational speed, HRT, and SRT influence biodegradation and micro-pollutant removal in membrane systems [ 22 , 23 ]. The selection of short HRT results in a high organic loading rate, increasing the viscosity and sludge concentration and increasing the filamentous bacteria growth [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Response Surface Methodology for Optimization of Rotating Biological Contactor Combined with External Membrane Filtration for Wastewater Treatment

et al. 2022

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A large amount of wastewater is directly discharged into water bodies without treatment, causing surface water contamination. A rotating biological contactor (RBC) is an attached biological wastewater treatment process that offers a low energy footprint. However, its unstable removal efficiency makes it less popular. This study optimized operating parameters in RBC combined with external membrane filtration (RBC-ME), in which the latter acted as a post-treatment step to stabilize the biological performance. Response surface methodology (RSM) was employed to optimize the biological and filtration performance by exploiting three parameters, namely disk rotation, hydraulic retention time (HRT), and sludge retention time (SRT). Results show that the RBC-ME exhibited superior biological treatment capacity and higher effluent quality compared to stand-alone RBC. It attained 87.9 ± 3.2% of chemical oxygen demand, 45.2 ± 0.7% total nitrogen, 97.9 ± 0.1% turbidity, and 98.9 ± 1.1% ammonia removals. The RSM showed a good agreement between the model and the experimental data. The maximum permeability of 144.6 L/m2 h bar could be achieved under the optimum parameters of 36.1 rpm disk rotation, 18 h HRT, and 14.9 d SRT. This work demonstrated the effective use of statistical modeling to enhance RBC-ME system performance to obtain a sustainable and energy-efficient condition.

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“…Alternative fouling mitigation strategies have been reported, such as the use of scouring agents, dosing flux enhancers (FEs), the use of vibrating/rotating membranes, and application of an electric field by using microbial electrolysis cell [3]. Particularly, cationic polymers have been successfully applied as FE in membrane bioreactors fed with real wastewater [4][5][6][7][8][9][10][11][12][13] and synthetic wastewater [14][15][16][17][18][19][20]. However, despite some successful applications, a proper FE dosing control tool is lacking, and different empirically based approaches are followed.…”

Section: Introductionmentioning

confidence: 99%

Optimising the Flux Enhancer Dosing Strategy in a Pilot-Scale Anaerobic Membrane Bioreactor by Mathematical Modelling

2022

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Flux enhancers (FEs) have been successfully applied for fouling mitigation in membrane bioreactors. However, more research is needed to compare and optimise different dosing strategies to improve the filtration performance, while minimising the use of FEs and preventing overdosing. Therefore, the goal of this research is to develop an optimised control strategy for FE dosing into an AnMBR by developing a comprehensive integrated mathematical model. The integrated model includes filtration, flocculation, and biochemical processes to predict the effect of FE dosing on sludge filterability and membrane fouling rate in an AnMBR. The biochemical model was based on an ADM1, modified to include FEs and colloidal material. We developed an empirical model for the FE-induced flocculation of colloidal material. Various alternate filtration models from the literature and our own empirical models were implemented, calibrated, and validated; the best alternatives were selected based on model accuracy and capacity of the model to predict the effect of varying sludge characteristics on the corresponding output, that is fouling rate or sludge filterability. The results showed that fouling rate and sludge filterability were satisfactorily predicted by the selected filtration models. The best integrated model was successfully applied in the simulation environment to compare three feedback and two feedforward control tools to manipulate FE dosing to an AnMBR. The modelling results revealed that the most appropriate control tool was a feedback sludge filterability controller that dosed FEs continuously, referred to as _10. Compared to the other control tools, application of the _10 controller resulted in a more stable sludge filterability and steady fouling rate, when the AnMBR was subject to specific disturbances. The simulation environment developed in this research was shown to be a useful tool to test strategies for dosing flux enhancer into AnMBRs.

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Wastewater Treatment in Membrane Bioreactors: The Use of Polyelectrolytes to Control Membrane Fouling

Cited by 10 publications

References 25 publications

Effect of Salt Concentration on Sodium Polyacrylate Diffusion in Convex Lens-induced Confinement (CLiC)

Effect of Salt Concentration on Sodium Polyacrylate Diffusion in Convex Lens-induced Confinement (CLiC)

Response Surface Methodology for Optimization of Rotating Biological Contactor Combined with External Membrane Filtration for Wastewater Treatment

Optimising the Flux Enhancer Dosing Strategy in a Pilot-Scale Anaerobic Membrane Bioreactor by Mathematical Modelling

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