Donnan Dialysis Process Research Articles

Alkali-driven Donnan dialysis for efficient ammonia recovery from wastewater: Performance, mechanism and optimization

Recovery of ammonia from wastewater is of practical importance toward a sustainable society. To this end, concentration-driven Donnan dialysis (DD) is a promising recovery method especially for its simplicity and negligible energy consumption. Upon the traditional salt-driven DD, the conceptive alkali-driven DD significantly enhanced mass transfer and removal efficiency, yet their performance in terms of key process parameter were not deeply understood and further optimization remained unclear. Models for salt (NaCl) and alkali (NaOH)-driven DD processes were thus established and the ammonia transfer was theoretically investigated. The results showed that a fluctuated Donnan equilibrium constant was found responsible for the superior performance of alkali-driven DD (mass transfer accelerated by 90 % than control). Interestingly, there was an optimal ammonia recovery mode via adjusting ratios of alkali/ammonia and cation/ammonia, two key parameters governing the process efficiency, based on which the salt-alkali coupling-driven DD process was further proposed. It was verified that the coupling-driven DD process achieved the ammonia removal kinetic value of 0.1632 h−1 under insufficient alkali conditions (accounting for 50 % ammonia concentration in feed) with lowest CO2 emissions of 3.49 kg CO2/kg NH4+. The descending overall efficiency of ammonia removal, following alkali-driven (0.2943 h−1) > coupling-driven (0.1632 h−1) > salt-driven (0.1228 h−1), was ascribed to the variations in the electrochemical potential of ions involved in the respective processes. In addition, the cost of chemical consumption for a coupling-driven DD process (3.99 $/kg NH4+) was close to that of a salt-driven process, but much lower than that of an alkali-driven process (14.81 $/kg NH4+). These finding insight the low-carbon and efficient recovery of ammonia from wastewater.

Selective recovery of Nickel from electroplating rinse bath wastewater by an integrated Donnan Dialysis/precipitation process

ABSTRACT The purpose of this work is to experimentally assess the application of a hybrid process, Donnan Dialysis (DD)/precipitation, for the selective separation and recovery of Nickel ions from Nickel electroplating rinse bath effluent. The primary objectives include facilitating water and Nickel reuse while protecting environmental resources. The separation of Ni (II) via an ion-exchange membrane was investigated experimentally. Operational parameters, such as the type of cation-exchange membrane, initial Nickel (II) concentration, and counter-ion concentration, were systematically studied to understand their impact on the productivity and selectivity of DD process. Simultaneously, the feasibility and efficiency of Ni (II) recovery from the receiver compartment through the precipitation process, forming Ni3(PO4)2, were examined. Results indicate that, under optimal conditions and with an initial Ni (II) concentration of 200 mg/L or less, the removal efficiency reached 90% after 24 hours of dialysis. Significantly, the type of cation-exchange membrane emerged as a crucial factor influencing Ni (II) removal. Additionally, employing PO4 3- as a precipitation reagent in a stoichiometric ratio yielded an excellent Ni recovery performance of 99%. Consequently, the treated effluent (feed compartment) becomes suitable for recycling in a new electroplating operation, while the solution obtained in the receiver compartment can be reused for another DD cycle process after Ni (II) recovery as Ni3(PO4)2. Importantly, this hybrid method produces a valuable Ni3(PO4)2 precipitate of excellent quality.

Graphene Oxide/Polyethyleneimine-Modified Cation Exchange Membrane for Efficient Selective Recovery of Ammonia Nitrogen from Wastewater.

Competition for the migration of interfering cations limits the scale-up and implementation of the Donnan dialysis process for the recovery of ammonia nitrogen (NH4+-N) from wastewater in practice. Highly efficient selective permeation of NH4+ through a cation exchange membrane (CEM) is expected to be modulated via tuning the surface charge and structure of CEM. In this work, a novel CEM was designed to form a graphene oxide (GO)-polyethyleneimine (PEI) cross-linked layer by introducing self-assembling layers of GO and PEI on the surface of a commercial CEM, which rationally regulates the surface charge and structure of the membrane. The resulting positively charged membrane surface exhibits stronger repulsion for divalent cations compared to monovalent cations according to Coulomb's law, while, simultaneously, GO forms π-metal cation conjugates between metal cations (e.g., Mg2+ and Ca2+), thus limiting metal cation transport across the membrane. During the DD process, higher NH4+ concentrations resulted in a longer time to reach Donnan equilibrium and higher NH4+ flux, while increased Mg2+ concentrations resulted in lower NH4+ flux (from 0.414 to 0.213 mol·m-2·h-1). Using the synergistic effect of electrostatic interaction and non-covalent cross-linking, the designed membrane, referred to as GO-PEI (20) and prepared by a 20 min impregnation in the GO-PEI mixture, exhibited an NH4+ transport rate of 0.429 mol·m-2·h-1 and a Mg2+ transport rate of 0.003 mol·m-2·h-1 in single-salt solution tests and an NH4+/Mg2+ selectivity of 15.46, outperforming those of the unmodified and PEI membranes (1.30 and 5.74, respectively). In mixed salt solution tests, the GO-PEI (20) membrane showed a selectivity of 15.46 (~1.36, the unmodified membrane) for NH4+/Mg2+ and a good structural stability after 72 h of continuous operation. Therefore, this facile surface charge modulation approach provides a promising avenue for achieving efficient NH4+-selective separation by modified CEMs.

Development of a predictive kinetic model with statistically analyzed parameters for Donnan Dialysis process

Donnan Dialysis (DD) utilizes ion exchange membranes that allow the selective transport of target ions from a feed solution to a concentrated receiver solution. The kinetics of DD involves boundary layer diffusion (BLD), diffusional membrane transport (MD), and a mixed regime where both mechanisms are active. The objective of the research was to develop an automated computational model that can predict nitrate, bicarbonate, and sulfate concentration profiles and transport mechanisms in DD processes. Experiments were conducted in a batch dialyzer in sole- and multi-component feed solutions and NaCl receiver solutions.Training of the model included numerical extraction of the BLD and MD coefficients from the experimental data; determination of the statistically significant parameters that affect the DD transport; development of correlations between these parameters and the kinetic coefficients; and mapping of the ratio between the boundary layer resistance and the membrane resistance to determine the transport mechanism.The predictive model, included the kinetic equations, i.e., the Nernst-Planck formulation, mass balances, and electro-neutrality, the correlations, and the mapping of the transport mechanism. The model was verified by the experimental data used for the model training and validated by independent datasets. Very good fits between the predicted and experimental concentration profiles were obtained, and the ability to determine the transport mechanism was demonstrated.

Ligand-Enabled Donnan Dialysis for Phosphorus Recovery from Alum-Laden Waste Activated Sludge.

While many nutrient recovery technologies target liquid waste streams, new strategies are required for effective phosphorus recovery from solid waste. This study reports an innovative ligand-enabled Donnan dialysis process to recover orthophosphate (P(V)) from alum-laden waste activated sludge (WAS). Four ligands, namely acetate, citrate, ethylenediaminetetraacetate (EDTA), and oxalate, were evaluated for P(V) release from a synthetic sludge containing 5 mM P(V) and 25 mM Al(III) and a real, alum-laden WAS with similar contents. Citrate and EDTA released more than 95% of P(V) at doses of 30 mM, outperforming acetate and oxalate. The ligand-based solubilization strategy was coupled with Donnan dialysis to recover P(V) into a clean sodium chloride draw solution. After Donnan dialysis with the synthetic sludge, the P(V) recovery's order was as follows: EDTA (54.4%) > citrate (41.7%) > oxalate (4.3%). The P(V) recovery efficiencies were slightly lower for Donnan dialysis with real, alum-laden WAS, namely 45.1% and 25.2% for EDTA and citrate addition, respectively, due to competitive effects exerted by other dissolved species. These promising results successfully demonstrated the proof-of-concept for ligand-enabled Donnan dialysis.

Coupling donann dialysis and electro-reduction process for nitrate removal from simulated groundwater

In this study, Donnan dialysis (DD) was applied to denitrify synthetic groundwater and electro-reduction was utilized as a post-treatment to remove the nitrate from the secondary waste generated during the DD process. Combined experiments were performed under continuous operating mode using a synthetic solution mimicking nitrate-contaminated groundwater found in agriculturally intensive regions of Italy. The influence of residence time on thie removal efficiency of nitrate in each reactor was studied. The effects of nitrate concentration, accompanying ions, and by-product formation were tested in the electrolyzer. In DD, nitrate, along with the accompanying ions bicarbonate and sulfate, was transported through an anion exchange membrane into a 100 mM NaCl receiving stream. Higher removal efficiencies were obtained with prolonged residence time, up to 65% at RT of 120 min. A maximum of 60% electro-reduction of nitrate, using a Cu-DSA electrode pair, was achieved at a residence time of ≥90 min. The specific energy consumption did not change significantly with the electrolysis RT ranging from 40 to 120 min. An increase in the nitrate concentration resulted in higher removal efficiency and reduced energy consumption. During the electrolysis of the DD waste, no ammonia was formed and 100% N2-selectivity was obtained.

Donnan Dialysis-Osmotic Distillation (DD-OD) Hybrid Process for Selective Ammonium Recovery Driven by Waste Alkali.

This work proposed an innovative and energy-efficient Donnan Dialysis (DD) and Osmotic Distillation (OD) hybrid process for alkali-driven ammonium recovery from wastewater. The efficiency and feasibility of ammonium removal and recovery from synthetic and real wastewater using NaOH and waste alkali were investigated. Ammonium in the feed first transported across the cation exchange membrane and accumulated in the receiver chamber. It is then deprotonated as ammonia, passing through the gas permeable membrane and finally is fixed as ammonium salt in the acid chamber. Our results indicated that employing waste alkali (red mud leachate) as driving solution led to excellent ammonium recovery performances (recovery efficiency of >80%), comparable to those of NaOH solution. When the initial ammonium concentration was 5 and 50 mM, the waste alkali driven DD-OD process achieved acceptable NH4+-N flux density of 16.8 and 169 g N m-2 d-1, at energy cost as low as 8.38 and 2.06 kWh kg-1 N, respectively. Since this alkali driven DD-OD hybrid process is based on solute concentration (or partial pressure) gradient, it could be an energy-effective technology capable of treating wastewaters containing ammonium using waste alkali to realize nutrients recovery in a sustainable manner.

Removal of phosphate by Donnan dialysis coupled with adsorption onto calcium alginate beads.

In this study the removal of phosphates from solution by Donnan dialysis and by adsorption onto calcium alginate beads were studied separately and then together. This hybrid process was conducted in order to benefit from each process, and it is an original and new combination. First, the Donnan dialysis process was performed with different parameters: the type of counter-ion, the concentration of the counter-ion, the initial phosphate concentration, the pH of the solution and the choice of anion-exchange membranes. Donnan dialysis achieved 68% and 12.5% phosphorus removal with AMX and AFN membranes respectively. Then a preliminary study into the adsorption of phosphate onto calcium alginate beads was carried out. A full factor design was applied in order to determine the effect of the main parameters and their mutual interactions for the adsorption process. The removal of phosphate onto calcium alginate beads reached 82.5%. Finally, coupling Donnan dialysis with adsorption onto calcium alginate beads for the removal of phosphate reached 89.5% with the AMX membrane. This hybrid process can be considered to be a solution for improving the contact time and for enhancing the removal of phosphate by 10% compared to adsorption onto calcium alginate.

Preparation of PVA-Based Hollow Fiber Ion-Exchange Membranes and Their Performance for Donnan Dialysis.

Hollow fiber type cation-exchange (C-HF) membranes and hollow fiber type anion-exchange (A-HF) membranes were prepared from poly (vinyl alcohol) (PVA)-based copolymer with cation-exchange groups and by blending PVA and polycation, respectively, by a gel fiber spinning method. In order to control the water content of the hollow fiber membranes, the membranes were cross-linked physically by annealing, and then cross-linked chemically by using glutaraldehyde (GA) solutions at various GA concentrations. The outer diameter of C-HF and A-HF membranes were ca. 1000 μm and ca. 1500 μm, respectively, and the thickness of the membranes were ca. 170 μm and 290 μm, respectively. Permeation experiments were carried out in two Donnan dialysis systems, which included mixed 0.1 M NaCl and 0.1 M CaCl2/C-HF /3 × 10−4 M CaCl2 and mixed 0.1 M NaCl and 0.1 M NaNO3/A-HF/3 × 10−4 M NaNO3 to examine ionic perm selectivity of the membranes. In the Donnan dialysis experiments using C-HF membranes, uphill transport of the divalent cations occurred, and, in the case of A-HF membranes, uphill transport of NO3− ions occurred. C-HF and A-HF membranes had about half of the flux in the uphill transported ions and also about half of the selectivity between the uphill transport ions and driven ions in comparison with those of the commercial flat sheet cation-exchange membrane (Neosepta® CMX) and anion-exchange membrane (Neosepta® AMX). Yet, IEC of C-HF and A-HF membranes were about one fifth of CMX and less than half of AMX, respectively. Since hollow fiber membrane module will have higher packing density than a flat membrane stack, the hollow fiber type ion-exchange membranes (IEMs) prepared in this study will have a potential application to a Donnan dialysis process.

Defluorination by Donnan Dialysis with seawater for seafood processing

Donnan Dialysis (DD) is developed in this study for continuous removal of fluoride from Antarctic krill by using seawater or concentrated seawater as the receiving solution. Results show that RO concentrate (1.0 mol L−1 NaCl) got the highest fluoride removal efficiency (93.66% ± 0.81%) with three stages at 0.01 cm s−1 flow velocity. Afterwards, fluoride removal experiment with a real krill solution showed 89.34% ± 0.55% under the optimized conditions. The product has fulfilled the fluoride content of US FDA standard and Canadian Food Inspection Agency in fish and fish products. Results also showed a lower loss of amino acids and proteins in comparison of conventional methods. Finally, a techno-economic evaluation showed that 4.0 USD per ton of Krill solution can be expected by this DD process. This study proves that Donnan Dialysis may be a sustainable defluorination process in removing high fluoride content of seafood by seawater or concentrated seawater.

Divalent Cation Removal by Donnan Dialysis for Improved Reverse Electrodialysis.

Divalent cations in feedwater can cause significant decreases in efficiencies for membrane processes, such as reverse electrodialysis (RED). In RED, power is harvested from the mixing of river and seawater, and the obtainable voltage is reduced and the resistance is increased if divalent cations are present. The power density of the RED process can be improved by removing divalent cations from the fresh water. Here, we study divalent cation removal from fresh water using seawater as draw solution in a Donnan dialysis (DD) process. In this way, a membrane system with neither chemicals nor electrodes but only natural salinity gradients can be used to exchange divalent cations. For DD, the permselectivity of the cation exchange membrane is found to be crucial as it determines the ability to block salt leakage (also referred to as co-ion transport). Operating DD using a membrane stack achieved a 76% reduction in the divalent cation content in natural fresh water with residence times of just a few seconds. DD pretreated fresh water was then used in a RED process, which showed improved gross and net power densities of 9.0 and 6.3%, respectively. This improvement is caused by a lower fresh water resistance (at similar open circuit voltages), due to exchange of divalent for monovalent cations.

The removal of chromium ions from water in Donnan dialysis process

The removal of chromium ions from water in Donnan dialysis process

Donnan dialysis − A new predictive model for non−steady state transport

A bond−graph model has been developed and applied to analyze the non−steady state transport kinetics of K+ cations in the Donnan dialysis (DD) process. The model is based on a pseudo−thermodynamic network analysis and takes into account all the simultaneously occurring processes and phenomena, i.e. diffusion through aqueous layers, interfacial and membrane ion−exchange kinetics, interdiffusion of K+ and H+ cations, diffusion of a free electrolyte in the membrane, and the osmotic transport of water. Moreover, membrane morphology represented by its heterogeneity and non−uniform distribution of ionogenic groups has been included in the model.The numerical simulations of fluxes demonstrated that the DD efficiency in the investigated system results from osmotic water transport as well as an electrolyte solution sorption into the cation−exchange membrane. These phenomena cause dilution of the stripping phase and enable free diffusion of the electrolyte between the external solutions, respectively. The reverse K+ ions flux from the stripping solution into the feed one observed in DD experiments results from the interdiffusion and non−exchange diffusion of the electrolyte.The numerical calculation results were compared with the experimental data measured for the DD systems operating with a low feed solution concentration (cf=0.01M) and high stripping solution concentration (cs up to 1M) resulting in observable osmotic flux of water. It was found that the developed model can be applied for the prediction of time−dependent concentration in the DD system. Consequently, the prediction of fluxes, concentration factors, recovery factors, etc. is also possible. The model calculations enable also the prediction of the experimental results as dependent on one of the main factors which influence DD efficiency, i.e. the stripping phase concentration.

Donnan dialysis based separation of gold(III) from electronic waste solutions using an anion exchange pore-filled membrane

Donnan dialysis technique was employed for the recovery of Au(III) from aqua regia solutions of electronic waste containing low concentrations of Au(III) in the presence of much higher concentrations of Cu(II) and Ni(II). The anion exchange pore-filled membrane was synthesized using in-situ photo-polymerization with polypropylene as the host membrane and (3-acrylamidopropyl)trimethyl ammonium chloride and (3-acryloxy-propyl)trimethoxysilane as the monomer and spacer, respectively. Photo-polymerization was carried out with ethylene glycol dimethacrylate as the cross-linker and 2,2-dimethoxy-2-phenyl acetophenone as the UV-initiator. The transport of Au(III) through this anion-exchange pore-filled membrane was studied using a two compartment cell where the receiver solution contained NaCl as the stripping reagent. Cu(II), which is the dominant metal ion in electronic waste solutions, did not interfere with the transport of Au(III) even at Au(III): Cu(II) mass ratios of up to 1:500. Gold from 100-fold diluted electronic waste solutions in aqua regia was successfully recovered (96.3%) after 4 cycles of Au(III) transport while at the same time insignificant fractions of the dominant metals in the electronic scrap (Cu and Ni) were transported. This study shows that Au(III) can be selectively recovered from diluted aqua regia solutions of electronic waste based on the proposed Donnan dialysis process.

Arsenate removal from sulphate-containing water streams by an ion-exchange membrane process

Abstract A possible limitation of applying Donnan dialysis for arsenate removal from drinking water supplies is when sulphate is present as an accompanying anion in the water to be treated, due to strong competition between arsenate and sulphate transport through standard grade anion-exchange membranes. This work aims at evaluating the feasibility of employing an ion-exchange membrane Donnan dialysis based process with a new strategy of using sulphate as the driving counter-ion for arsenate counter-transport and removal from sulphate-containing drinking water streams. The process performance with different arsenate receiving solutions (containing chloride or sulphate as driving counter-ions and with or without arsenic precipitation) was investigated and compared. Experiments were carried out to separate arsenate from contaminated water comparing the performance of three anion-exchange membranes: one with mono-valent anion permselective properties and two standard grade membranes. As selection criteria, the transport rate of arsenate and its membrane retention were investigated. The effects of pH variation and co-ion (cation) leakage on the Donnan dialysis process efficiency were also studied. Efficient arsenic removal was achieved through integrating Donnan dialytic transport of arsenate with its simultaneous precipitation in the receiving compartment with FeSO 4 . The process proposed is environmentally friendly and with minimal maintenance requirements, which makes it especially attractive to be applied in rural areas located far from centralized drinking water supply infrastructures.

Nernst Planck approach based on non-steady state flux for transport in a Donnan dialysis process

In the present work, Nernst Planck (NP) approach based on non-steady state flux has been explored to predict the transport kinetics in a Donnan dialysis process. The calculations have been carried out for pure and mixed bi-ionic monovalent–monovalent systems. Appropriate forms of the equations have been derived and then solved numerically by finite difference method using appropriate initial and boundary conditions. The results of the calculations have been compared with the experimental transport profiles and NP calculations based on pseudosteady state approximation. It has been found that the NP method based on non-steady state flux is capable of predicting the transport kinetics for both pure and mixed ionic systems for all salt compositions. On the other hand, NP approach based on pseudosteady state approximation works only at high salt concentrations (>0.1M) for pure ionic systems. Also, the approach completely fails for mixed ionic systems. The NP approach with non-steady state flux is capable of accounting the accumulation of ions in the membrane and the time lag characteristics prevalent dominantly in the initial time scales of a membrane transport process.

Removal of Cu2+ from aqueous solution using proton exchange membrane by Donnan dialysis process

In the context of increasing heavy metal pollution (e.g., Cu2+, Cd2+, Pb2+ and Zn2+) in Liao River Basin of China in recent years due to metallurgical refinery, this study investigated the removal of Cu2+ from aqueous solution by Donnan dialysis process. Na+ was selected as the counterion, while GEFC-107 proton exchange membrane (GEFC Co., China) was used as the ion exchange membrane. Transport of Cu2+ from feed phase to receiver phase was enhanced by increasing \({{{\text{Na}}_{\text{R}}^{ + } } \mathord{\left/ {\vphantom {{{\text{Na}}_{\text{R}}^{ + } } {{\text{Cu}}_{\text{F}}^{{ 2 { + }}} }}} \right. \kern-0pt} {{\text{Cu}}_{\text{F}}^{{ 2 { + }}} }}\) ratio (subscripts R and F denote as receiver and feed phases, respectively). For the initial Cu2+ concentration of 200 mg L−1 and \({{{\text{Na}}_{\text{R}}^{ + } } \mathord{\left/ {\vphantom {{{\text{Na}}_{\text{R}}^{ + } } {{\text{Cu}}_{\text{F}}^{{ 2 { + }}} }}} \right. \kern-0pt} {{\text{Cu}}_{\text{F}}^{{ 2 { + }}} }}\) ratio of 20:1, a removal efficiency of 95.31 % was achieved for 190 min dialysis. The adsorption percentage by the proton exchange membrane increased from 12.12 to 85.15 % when the initial Cu2+ concentration decreased from 200 to 20 mg L−1. The kinetics data for Cu2+ removal was best interpreted by the first-order model. The removal efficiency decreased from 89.09 to 72.43 % when the proton exchange membrane was reutilized three times without membrane washing using acid. Higher initial pH of receiver phase or lower initial pH of feed phase facilitated the Cu2+ transport from feed to receiver phase. The feasibility of Donnan dialysis collaborated with precipitation to remove Cu2+ was found to be not suitable for Cu2+ removal with high concentration, i.e., initial concentration 200 mg L−1, since only a removal efficiency of Cu2+ of 54.08 % was achieved.

Kinetic modeling and selectivity of anion exchange in Donnan dialysis

The objective of this work was to compare selective sorption and transport behavior of a Selemion AMV membrane for different anions with a theoretically derived kinetic model describing the Donnan dialysis (DD) process. This analysis resulted in a suggested relation for the diffusivity of small ions through “nanochannels” of ion exchange membranes. Mass transfer through boundary layers and membrane diffusion were modeled on the basis of the Nernst–Planck equation by introducing constant diffusivity ratios between the exchanging counter ions. To indentify the kinetic and selectivity coefficients, DD batch experiments with sodium nitrate, sulfate or dihydrogen phosphate as feed electrolytes and sodium chloride as receiver electrolyte were conducted. The derived kinetic model simulated the measured concentration changes very precisely after fitting three concentration-independent parameters and the concentration-dependent permeability coefficient. The selectivity sequence was found to be nitrate>sulfate>dihydrogen phosphate>chloride, while this sequence is strongly connected to activity in solution and in the membrane. This influence was very significant for sulfate, which resulted in higher removal efficiency than expected. Regarding diffusivity the identified sequence was nitrate>sulfate>chloride>dihydrogen phosphate. These results led to a correlation that describes diffusivity of counter ions through nanochannels as a function of hydrated cross section area and valence.

Simple Model for Characterizing a Donnan Dialysis Process

The objective of this work is to characterize the kinetics of Donnan dialysis process by a simple model. The Nernst–Planck equation is simplified by neglecting the membrane swelling pressure and assuming an average diffusion coefficient for all ions. Experimental data are presented on the permeation of monovalent phosphate ions from a KH2PO4/NaH2PO4 feed solution to a NaCl receiver solution using two different anion exchange membranes: a low flux membrane (Fumasep FAB) and a high flux membrane (Selemion AMV). Measurements indicate a brief initial ion exchange process in which the membrane is loaded with phosphate ions. Phosphate transport data fit the predicted correlations and provide values of the overall kinetic coefficient. The kinetic coefficients derived from both membranes were found to increase linearly with the membrane phosphate concentration. The phosphate dialysis data of the low flux membrane were found to be controlled by a diffusive process, while the data of the high flux membrane were found to be mass transfer controlled. The increase of the kinetic coefficient with phosphate concentration is shown to be related to the increase in membrane ion diffusivity with its solution concentration.

Transport of arsenate through anion-exchange membranes in Donnan dialysis

The transport of arsenate across the main known types of polymeric anion-exchange membranes: heterogeneous, homogenous and monovalent-anion-permselective ones, was systematically studied under batch and continuous Donnan dialysis operating conditions. The experiments were carried at a low arsenate level of 0.1mmolL−1 (equivalent to about 7.5mgL−1 of As) in the feed solutions in order to allow for elucidating the transport rate and removal efficiencies of As within the concentration range relevant for contaminated drinking water supplies. The results are discussed in the light of the existing knowledge on the properties of the investigated anion-exchange membranes, complemented, when missing, with experimental data obtained in the present study. It has been found that the Donnan dialysis process performance depends strongly on the anion-exchange membrane used under batch operating conditions, but the differences vanish for a continuous operation mode, for which similar degrees of As removal have been obtained. Implications of the experimental findings as applied to removal of arsenate from dilute aqueous solutions are considered. The most appropriate anion-exchange membranes appear to be those possessing a relatively open structure and low tortuosity of the polymeric matrix. On the other hand, the use of membranes with monovalent-anion-permselective properties is not recommendable because of a slow transport rate of arsenate and its significant retention in the membrane phase.