A demanda atual por recursos hídricos com quantidade e qualidade exige que todos os efluentes domésticos sejam tratados de maneira adequada para minimizar os impactos ambientais causados no meio ambiente. As estações de tratamento de efluentes domésticos que utilizam sistemas tradicionais de tratamento em muitos casos não conseguem atingir os valores de remoção de poluentes exigidos pelas legislações ambientais e, portanto, processos avançados de tratamento de efluentes devem ser realizados para garantir tal atendimento. No presente trabalho foi realizada a coleta e caracterização físico-química de amostras em diferentes pontos de processo na estação de tratamento de efluentes do Campus Litoral Norte da Universidade Federal do Rio Grande do Sul. O monitoramento foi realizado durante 33 semanas e mostrou que o efluente tratado final da ETE apresentou valores elevados de poluentes como, por exemplo, nitrogênio total Kjeldahl (NTK), amônia e demanda química de oxigênio (DQO), o que impossibilita seu lançamento. O processo de eletrodiálise do efluente tratado da ETE foi realizada em uma planta piloto onde foram realizados 2 diferentes tipos de ensaios de eletrodiálise. No 1º ensaio o objetivo era avaliar o transporte iônico de poluentes do efluente após a eletrodiálise e os resultados encontrados mostram que, o efluente tratado por eletrodiálise, foram encontrados valores de concentração média abaixo de 1 mg/L para os ânions fluoreto, cloreto, nitrito e nitrato e para os cátions sódio, amônio, potássio e magnésio. Os resultados encontrados na caracterização fisico-química do efluente tratado indicam que o mesmo pode ser utilizado como água de reúso na agricultura, para fins urbanos e na psicicultura se for realizada a correção do pH. O 2º ensaio tinha como objetivo avaliar o comportamento das membranas através da qualidade do efluente após sucessivas eletrodiálises sem realizar a limpeza do sistema e os resultados encontrados mostram que foram obtidos valores de concentração média abaixo de 10 mg/L para todos os ânions e cátions. Os resultados encontrados pela caracterização fisico-química deste efluente tratado por eletrodiálise indicam que o mesmo pode ser utilizado como água de reúso na agricultura e reúso para fins urbanos se for realizada a correção do pH e a remoção da turbidez do efluente. Para o reúso na psicicultura, além da correção do pH, deve ser realizada a remoção do ânion nitrato para valores inferiores a 5 mg/L. / The current demand for water resources with quantity and quality requires that all domestic effluents must be adequately treated to minimize the environmental impacts caused on the environment. Municipal sewage treatment plants (MSTP) using traditional process in many cases fail to achieve the pollutant removal required by environmental. Therefore, advanced wastewater treatment processes must be carried out to ensure such care. The present work carried out the sampling and characterization samples at different process points from the wastewater treatment plant (WWTP) of Campus Litoral Norte of the Universidade Federal do Rio Grande do Sul. The monitoring was performed during 33 weeks and showed that the final treated effluent of the WWTP showed high values of pollutants such as NTK, ammonia and COD, which makes it impossible to discharge in nature. The process of electrodialysis of the final effluent, after the treatment at the WWTP, was carried out in the pilot plant. Two different electrodialysis tests were carried out. On the first test, the objective was to evaluate the ionic transport of pollutants from the effluent after the electrodialysis and the results found show that the effluent treated were found values of average concentration below 1 mg / L were obtained for fluoride, chloride, nitrite and nitrate anions and for sodium, ammonium, potassium and magnesium cations. The results found by the physicochemical characterization of the effluent indicate that it can be used as reuse water in agriculture, for urban proposes and in pisciculture if the pH correction is performed. In the second test, the objective was to evaluate the behavior of the membranes through the quality of the effluent after successive electrodialysis without cleaning the system. The results obtained in the effluent after the second test showed that mean values below 10 mg/L were obtained for all anions and cations. The results obtained by the physicochemical characterization of the effluent indicates that it can be used as reuse water in agriculture and for urban proposes reuse if the correction of the pH and the removal of the turbidity of the effluent is carried out. For reuse in the pisciculture, besides the correction of the pH, the removal of the nitrate anion should be carried out to values below 5 mg/L.

Em processos de eletrodeposição, substâncias à base de cianeto são empregadas como complexantes e portadores do metal a ser depositado. Entretanto, a toxicidade associada ao cianeto e a evolução das legislações ambiental e trabalhista impulsionaram a exploração de matérias-primas alternativas aos sais cianídricos. Um estudo desenvolvido no Instituto de Pesquisas Tecnológicas avaliou a modificação de um banho comercial isento de cianeto para processos de deposição de cobre em substratos de Zamac. Neste estudo, foi utilizado um banho à base do ácido 1,hidroxietano-1,1- difosfônico, ou HEDP, um composto orgânico capaz de formar complexos estáveis com íons metálicos. Para viabilizar a substituição do cianeto pelo HEDP, deve-se consolidar uma metodologia para o tratamento do efluente gerado nas operações que o envolvam. A técnica de eletrodiálise surge como uma alternativa considerada limpa, que dispensa mudanças de fase e adição de produtos químicos ao processo. O método consiste na utilização de membranas íon-seletivas para promover a separação de espécies iônicas entre soluções utilizando a diferença de potencial elétrico entre dois pólos como força motriz. Neste trabalho, avaliou-se a aplicação da eletrodiálise no tratamento de um efluente galvânico à base de HEDP. Foram utilizadas soluções sintéticas simulando as águas de lavagem de um banho toque composto por complexos de cobre e HEDP. A construção das curvas de polarização permitiu a determinação da densidade de corrente limite a ser empregada na eletrodiálise. Nos ensaios de eletrodiálise, foi avaliada a extração percentual dos íons de cobre e de HEDP das soluções sintéticas. As membranas utilizadas também foram analisadas para investigação de possíveis alterações estruturais. Os resultados mostraram extração de até 99,7% de cobre e 94,4% de HEDP, possibilitando o reaproveitamento das soluções tratadas nos tanques de lavagem e, simultaneamente, a reutilização dos íons extraídos, compensando perdas por arraste. As análises químicas comprovaram a presença de complexos aniônicos formados entre o cobre e o HEDP. A alteração na acidez do meio permite a separação deste complexo e a recuperação de cobre e de HEDP em compartimentos separados. As análises realizadas por MEV/EDS mostraram a presença de picos de cobre e fósforo nas superfícies das membranas. A avaliação feita por um processo de lixiviação indicou a ocorrência de depósitos nas superfícies das membranas. Os incrementos na acidez das soluções finais indicam recuperação do HEDP e as análises de foto-oxidação do ácido orgânico apontaram degradação inferior a 7% nos ensaios avaliados. / In electroplating processes, cyanide-based substances are used as complexing agents and as raw materials in form of metal salts. However, the toxicity associated with cyanide and the evolution of environmental and employment laws have been promoting research for the development of new raw materials in electroplating processes. A study conducted at the Institute for Technological Research evaluated the modification of commercial cyanide free bath for processes of copper coating on zinc alloys. In the performed study, a news alkaline copper bath was formulated using 1 hydroxyethane-1, 1 diphosphonic, or HEDP, an organic compound known for forming stable complexes with metal ions. To support the replacement of cyanide, it becomes necessary to consolidate a methodology for treatment of the wastewaters generated by operations involving HEDP. Electrodialysis is considered a clean technology which dispenses phase changes and the addition of chemicals to the treatment process. The method consists in the use of ion-selective membranes to promote the separation of ionic species from solutions, using as driving force the difference of electrical potential between two electrodes. In this study the application of electrodialysis in the treatment of electroplating wastewaters containing HEDP was evaluated. Synthetic solutions were prepared, simulating the rinsing water from a bath composed of copper and HEDP complexes. The construction of the current-voltage-curves allowed the determination of the limiting current density applied in the electrodialysis stack. During electrodialysis, the percentage of extraction of copper and HEDP from synthetic solutions were evaluated. The membranes used were analyzed to investigate possible structural changes. The results showed extracting rates up to 99,7% copper and 94,4% HEDP, allowing the reuse of solutions in rinse steps and simultaneously reuse of copper and HEDP ions to compensate drag-out losses. Chemical analysis confirmed the presence of anionic complexes formed between copper and HEDP. The decrease of pH allows the separation of these complexes and the recovery of copper and HEDP in separate compartments. The results of SEM/EDS analysis of membranes showed the presence of peaks of copper and phosphorus. The analysis made by a leaching process showed the occurrence of deposits on the membranes surface. The increases in acidity of the final solutions indicate recovery of HEDP and the photooxidation analysis indicated degradation of the organic acid under 7% in evaluated samples.

Este trabalho teve como objetivo avaliar a aplicação da eletrodiálise reversa no tratamento de efluente final de refinaria para reuso em sistema de resfriamento. O estudo foi conduzido nas instalações da Refinaria Gabriel Passos (REGAP)- MG, com efluente real, proveniente da saída da Estação de Tratamento de Despejos Industriais (E.T.D.I.), e utilizando para os testes uma unidade-piloto de eletrodiálise reversa com capacidade de tratamento de 2 m3/h. A utilização do processo de dessalinização por EDR teve o objetivo de reduzir sólidos totais dissolvidos no efluente de aproximadamente 1.240 mg/L para 310 mg/L, o que equivale a cloretos de 460 mg/L e 100 mg/L respectivamente, para atingir a qualidade requerida para água de make-up da torre de resfriamento da REGAP. Inicialmente foi feita uma avaliação comparativa com o processo de osmose inversa, no qual foi constatada, com o uso da EDR, a maior continuidade operacional, menores problemas de incrustação e menor exigência para o pré-tratamento do efluente. No estudo com a EDR foram realizados testes variando-se a vazão, de 600 a 2000 L/h de produto; voltagem de 200 a 370V e número de estágios. Durante os testes foi realizado o monitoramento operacional e analítico da água de alimentação da EDR, do produto (solução diluída) e do rejeito (concentrado salino), sendo os dados avaliados e correlacionados para determinação da densidade de corrente, taxa hidráulica, eficiência e taxa de remoção de sais. A análise da formação de incrustações e deposições na superfície das membranas levou ao estabelecimento de um procedimento de limpeza química. O estudo foi conduzido de forma a obter a otimização da operação com rendimento necessário na remoção de sólidos dissolvidos, menor custo energético e de manutenção. Após os testes foi selecionada a condição otimizada da unidade piloto: módulo em 2 estágios, vazão de 1,1 m3/h e voltagem de 275V. Para este condição o consumo energético foi de 1,95 KWh/m3 de efluente tratado. Os resultados mostraram a viabilidade técnica-econômica do uso da EDR para remoção de sais de efluente final de refinaria para aplicação em reposição de sistemas de resfriamento. / This study aimed the evaluation of the application of electrodialysis reversal in final effluent treatment targeting the reuse in cooling towers. The study was done in Gabriel Passos Refinery (REGAP) - MG, with real effluent, from the Industrial Effluent Treatment Station (ETDI), and was held in a pilot plant of electrodialysis reversal with a treatment capacity of 2 m3 / h. The use of the desalination process with EDR target the reduction of total dissolved solids in the effluent of about 1.240 mg / L to 310 mg / L, equivalent to chlorides of 460 mg / L and 100 mg / L respectively, to reach the required quality of make-up water in the REGAP cooling tower. It was originally done a comparative evaluation with reverse osmosis process, another method of membrane desalination. Electrodialysis was selected because of its operating stability, less problems with scaling and fouling, dispensing the use of conditioning chemicals, and the requirement of a simpler pre- treatment The tests with EDR were carried out ranging the product flux for 600 to 2.000 L/h, the voltage for 200 to 370V and the number of hydraulic stages. During the tests were analyzed operational and analytical data in the EDR feed, product (diluted solution) and reject (concentrated solution), being the parameters analyzed and correlated to determine the current density, hydraulic rate, efficiency and salts removal rate. The analysis of fouling and deposition formation on the membranes surface led to an establishment of a chemical cleaning procedure. This study was conducted in order to obtain the operational optimizing with the necessary income to remove dissolved solids, with lower energy cost and maintenance. After the tests was selected the optimum condition for the pilot plant: stack in 2 stages, flow rate of 1.1 m3/h and voltage of 275V. In this condition the power consumption was 1.95 KWh/m3 of treated effluent. The results showed the technical and economic feasibility for the EDR in removing salts from refinery effluents for reuse in make up of cooling systems.

Nitrogen pollution in the environment creates challenging problems globally and locally and can be effectively controlled by a significant reduction in nitrogen release into the natural water system. In addition, nutrients in high-strength wastewater can be recovered as valuable resources such as different types of ammonium solutions for industrial and agricultural utilizations. Selective ammonia separation from high-strength wastewater can be achieved by bipolar membrane electrodialysis (BMED), a relatively new ion exchange technology. A series of 8 bench-scale BMED experiments with bipolar membranes and cation exchange membranes were performed under various voltage applications. Ammonia in the wastewater was rapidly separated and recovered as a high purity ammonium hydroxide solution. BMED operation for 30 minutes at 5.0 V per cell pair was found to be ideal for high purity ammonium hydroxide production and low electrical energy consumption. Additionally, effective organic fouling control and low energy consumption were achieved. The experiments showed a decrease in the feed pH making it ideal for applications in solid-state anaerobic digestion with leachate recirculation. The application of leachate recirculation in solid-state anaerobic digestion (SSAD) has proven effective for mobilizing nutrients and diluting toxic byproducts to enhance biogas production. The leachate after recirculation contains accumulated ammonia and an increased pH and requires water and chemicals for dilution and pH adjustment prior to recirculation. The data from the experiments were used to construct a numerical model for a hypothetical lab-scale and pilot-scale bipolar membrane electrodialysis and solid-state anaerobic digestion with leachate recirculation (BMED-SSAD) system. A final ammonia concentration of less than 2000 mg-N/L in the reactor was found to be achievable by lab-scale (6 mA/cm2) and pilot-scale (12 mA/cm2) BMED-SSAD and low electric energy consumption. The results suggest that BMED is an attractive solution for ammonia separation from high-strength wastewater. / Thesis / Master of Applied Science (MASc)

Electrodialysis is a membrane separation process that uses an electrical potential to drive the separation. The performance of these systems is largely based on the performance of their ion exchange membranes (IEMs). This research focused on enhancing the performance of IEMs for electrodialysis through surface modification techniques involving chitosan bonded to the surface of commercially available cation exchange membranes (CEMs). The surface functionalization techniques resulted in membranes with improved electrodialysis performance. This research also explored the processing framework to produce functionalized sulfonated PEEK (sPEEK) nanofibers for future consideration as cation exchange membranes. Chitin was deacetylated to form the functionalized biopolymer chitosan, then applied to the surface of CEMs, rendering them more hydrophilic. These membranes were evaluated across several electrodialysis performance metrics. Results demonstrate that adjusting the degree of deacetylation of chitosan to enhance membrane hydrophilicity positively impacted electrodialysis performance. Furthermore, this research evaluated the effectiveness of similarly functionalized membranes to extract Lithium from brine solutions. The chitosan-coated membranes showed improved electrodialysis performance, including enhanced flux, limiting current density, system resistance, selectivity, and fouling resistance. Lastly, the sPEEK nanofibers were produced for the fabrication of ion exchange membranes by manipulating operational parameters to assess their impact. This research presents the successful functionalization of PEEK via sulfonation and electrospinning of the resulting sPEEK. These nanofibers were then pressed to form a solid sPEEK membrane. It was observed that changes in electrical potential and rotational speed influenced fiber diameter and spinnability. A correlation was established between membrane surface hydrophilicity and electrodialysis performance metrics in desalination and lithium extraction applications. This research advanced the understanding of structure-property relationships for CEMs. The research herein proposes techniques for industries such as desalination and lithium extraction that can meet growing demands for clean water and sustainable methods for producing high-value raw material streams.

Six Kaolins were chosen at random. These Kaolins were electodialyzed in a Mattson type dialysis cell. Titration curves were run on these both before and after being dialyzed to determine base exchange capacity and optimum pH. Debye-Scherrer x-ray powder diffraction patterns were made on each Kaolin both untreated and electrodialyzed in order to determine if electrodialysis had any effect on the crystal structure of the Kaolin. Quantitative spectrographic analyses were made to determine what elements and how much of each element was removed by dialysis. The same process was run and tests were made on Tennessee Ball Clay and Bentonite as a basis of comparison. It was confirmed that the Bentonite was decomposed by electrodialysis. / Master of Science

The dominant organic phosphorus compound classes were characterized in marine samples using a new, high recovery method for isolating and concentrating bulk dissolved organic matter (DOM) called combined electrodialysis+reverse osmosis (ED/RO). In contrast to earlier studies which use ultrafiltration (UF) to recover only the high molecular weight DOM, ED/RO is capable of isolating both low molecular weight (LMW) and high molecular weight (HMW) DOM. Samples were collected from a broad range of marine environments: along a transect incorporating coastal and offshore waters off the Southeastern United States, in Effingham Inlet, a Pacific fjord located on Vancouver Island, British Columbia and in the Amundsen Sea, Antarctica. Results from phosphorus nuclear magnetic resonance (31P NMR) analysis reveals a similar abundance of P compound classes between samples, phosphate esters (80-85%), phosphonates (5-10%) and polyphosphates (8-13%). These samples contain significantly higher proportions of polyphosphate P and P esters and lower proportions of phosphonates than measured in previous studies using the UF method. The much higher levels of polyphosphate detected in our samples suggests that polyphosphate is present mainly in the LMW DOM fraction. Polyphosphates in DOM may be present as (or derived from) dissolved nucleotides or organismal polyphosphate bodies, or both. Low molecular weight P esters are likely composed of phosphoamino acids and small carbohydrates, like simple sugar phosphates and/or dissolved nucleotides. Phosphonates in DOM are more prevalent as HMW phosphonate compounds, which suggests that LMW phosphonates are more readily utilized in marine ecosystems. Overall, the investigation of DOM across a size spectrum that includes both the HMW and the LMW fractions reveals a new picture of phosphorus distribution, cycling and bioavailability.

Reverse electrodialysis (RED) is a technique that can capture electrical potential from mixing two water streams of different salt concentration through permselective ion exchange membranes. Effective design of ion exchange membranes through structure optimization is critical to increase the feasibility of salinity gradient power production by RED. In this work, we present the preparation of organic-inorganic nanocomposite cation exchange membranes containing sulfonated polymer, poly (2,6-dimethyl-1,4-phenylene oxide), and sulfonated silica (SiO2-SO3H). The effect of silica filler size at various loading concentrations on membrane structures, electrochemical properties, and the RED power performance is investigated. The membranes containing bigger-sized fillers (70 nm) at 0.5 wt% SiO2-SO3H exhibited a relatively favorable electrochemical characteristic for power performance: an area resistance of 0.85 Ω cm2, which is around 9.3% lower than the resistance of the membranes with smaller filler particles. The power performance of this nanocomposite cation exchange membrane in a RED stack showed 10% higher power output compared with the membranes containing small particle size and achieved the highest gross power density of 1.3 W m-2. Thus, further optimized combination of material properties and membrane structure is a viable option for the development of effective ion exchange membrane design, which could provide desirable electrochemical performance and greater power production by RED.

With the continual concern over the presence of naturally occurring and anthropogenic inorganic and trace organic contaminants in the aquatic environment there is a growing need for the implementation of innovative treatment processes for the elimination of these contaminants from natural waters and wastewater effluents. While conventional treatment methods are ineffective in the removal of emerging contaminants such as steroidal hormones and pesticides, membrane technology, including electrodialysis (ED), has been highlighted as a potential treatment option. However, the clear lack of fundamental understanding of the behaviour of contaminants in ED is a current limitation for its extensive utilisation and is a critical issue that needs to be addressed. ED processing potentialities have not been fully exploited and more research is needed to account for all the key parameters such as contaminant physicochemical properties, solution chemistry and the presence of organic matter. The purpose of this study was to elucidate the mechanisms of inorganic and trace organic contaminant removal by ED. The inorganic contaminants fluoride, nitrate and boron were selected due to their ubiquitous nature in the environment and public health concerns resulting from longterm exposure. The hydrated radius and strength of hydration shells played a significant role in ionic transport, whereby nitrate with a smaller hydrated radius was removed more effectively (94.1 %) than fluoride (68.3 %) with a larger hydrated radius. While fluoride and nitrate removal was pH independent, the pH dependent speciation of boron enhanced its removal with increasing pH. Territorial binding and/or complexation of the inorganics with organic matter enhanced removal. The removal of a range of trace inorganics (e.g. arsenic, calcium, magnesium, uranium) from a brackish groundwater from a remote Australian community was investigated. Undissociated inorganics were not transported through the membranes, whereas dissociated inorganics were due to electrostatic attraction. At acidic-neutral conditions ionic transport was the dominant removal mechanism. At neutral to alkaline conditions insoluble carbonate species precipitated and deposited as a membrane scaling layer (60 μm). This has serious implications for the long-term practical applicability of ED to treat real waters as scaling increased ED stack resistance (pH 3: 27.5 4, pH 11: 50 4) and decreased total dissolved solids removal (pH 3: 99 %, pH 11: 89.5 %). While the treatment of trace organics by other membrane processes has been widely studied, their fate in ED and interaction with ED membranes is relatively unknown. Trace contaminant-membrane interaction studies were undertaken to quantify the partitioning of trace organics; namely steroidal hormones and the pesticide endosulfan, to ED membranes by measuring membrane-water partition coefficients (log KM). The extremely high sorption capacity of the membranes was attributed to hydrogen bonding between the trace organic and membrane functional groups. Hormone sorption during ED was influenced by solution pH and organic matter. In the case of estrone, membrane sorption decreased at pH 11 (487 μg/cm3) compared to pH 7 (591 μg/cm3) due to dissociation and membrane electrostatic repulsion .At pH 11, repulsion between dissociated estrone and HA coupled with membrane electrostatic attraction resulted in increased sorption. The findings from this study highlight that the transport of trace contaminants will depend largely on the characteristics of the membranes used in the ED process as well as the physicochemical characteristics of the contaminants, their interaction with the ED membranes and the presence of other inorganic and/or organic compounds. The knowledge gained has direct applications to current problems and uncertainties in water and wastewater treatment with regards to the fate and transport of contaminants.

Around 770 million people lack access to improved drinking water sources (WHO 2013), urgently necessitating implementation of contaminant removal by e.g. desalination systems on a large scale. To improve water quality and enable use of brackish water sources for human consumption in remote arid areas, a directly coupled wind – electrodialysis system (Wind-ED) was developed. Modularity, sustainability and above all suitability for the practical use in off-grid locations were the main motivations and design objectives. The direct coupling of wind energy with membranes reduces the system costs as well as technical drawbacks associated with using intermediate energy storage systems. During this research, systematic experiments were performed using the Wind-ED system in order to determine desalination performance and clean water production, specific energy consumption (SEC) and current efficiency (ηc) under relevant conditions, such as varying: i) wind speed, ii) wind turbulence intensity, iii) oscillation periods, iv) varying NaCl concentrations and v) flow rates. Moreover, the competitive removal of four commonly available inorganic contaminants in brackish groundwater sources, nitrate (NO3-), fluoride (F-), sulphate (SO42-) and chloride (Cl-), were investigated. Firstly, to establish a systematic understanding of how and to what extent energy fluctuations influence the transport of the salt (i.e. NaCl) ions across the membranes, experiments were conducted using pulsed electric field assisted electrodialysis (pulsed-ED) over a wide range of frequencies (0.001 – 10 Hz) and duty cycles (20 – 80). The results showed that pulsation applied in the sub-limiting regime resulted in reduced water production, explained by the delays caused by the off-periods during the pulsed desalination process. At higher current densities, pulsation led to considerable improvements in current (e.g. up to 95%, for a feed solution of 500 mg/L and a pulse regime of 1 Hz at 50 V peak voltage) and significant reduction in water dissociation, explained by a reduction of concentration polarisation. Importantly, the pulsation had no significant effect on energy consumption or current efficiency suggesting that ED could be suitable for direct coupling to fluctuating energy sources such as wind energy. ED was consequently coupled to a wind turbine system and a series of desalination tests were performed over a wide range of wind speeds (2-10 m/s), turbulence intensities (TI of 0-0.6) and oscillation periods (0-180 s). Results showed that water production and SEC increased with wind speed. However, both the water production and SEC stopped increasing as the power output from the turbine levelled off at wind speeds above the rated value (vrated: 7.9 – 8.4 m/s). The impact of wind speed fluctuations on the system performance were insignificant up to a TI of 0.4. The desalination performance declined under high turbulence intensity fluctuations (TIs ≥ 0.5) and long periods of oscillation (> 40 s), as the wind-ED system periodically cycled off in response to operation below the cut-in wind speed of the wind turbine (vcut-in: ~ 2 m/s). The off-cycling of the system caused significant delays in the desalination process, and thus resulted in reduced water production. Further reduction in the water production resulted as the wind-ED system operated under intermittent wind speed conditions with off-wind periods longer than 10 s. It was concluded that the main challenge in direct coupling of ED to a wind resource was not the magnitude of the fluctuations but the impact of the power cycling off during long periods of oscillation and lengthy periods of no wind. Interestingly, the SEC of the process remained relatively unaffected by the fluctuations and intermittencies in the wind resource. The effect of energy fluctuations on the competitive transport of F-, Cl-, NO3- and SO42- from artificial brackish water (TDS ~4350 mg/L) was investigated using different sets of real wind data. The ion removal, independent of the wind regime tested, followed the order: NO3- ≥ Cl- > F- > SO42-. The competitive removal of the ions was linked to differences in physicochemical properties (i.e. hydration energy, ionic mobility and valence). The specific selectivity (e.g. preferential transport of NO3- over SO42- ions) was found to increase with concentration polarisation being either minimised (by lowering the mean wind speed) or disrupted (by fluctuations in the wind resource). The results from flow rate and feed concentration experiments, showed that power production of the wind turbine depended on not only the available wind energy but also the resistance of the load (i.e. the ED stack). Thus, increasing the feed concentration and the flow rate resulted in reduced resistance in the ED stack (Rstack), which inversely influenced the current induction counter torque force applied on the shaft of the wind turbine and caused the rotor to spin at a lower angular velocity. This led to increased sensitivity of the wind-ED system to wind speed fluctuations (e.g. system cycled off due to extreme fluctuations and intermittencies with low TDS feed concentration of 2400 mg/L) and hence a reduction of desalination performance. Impact of flow rate on the SEC was found to be negligible; this was attributed to the automatic voltage to current adjustments done by the wind turbine, in order to minimise the impacts of Rstack on the power production by the turbine at a given wind speed. Increased flow rate and resulting shrinkage of the boundary layer’s thickness, caused the concentration profiles at the solution-membrane interface to become steeper. This favoured the transport of ions with the highest diffusion coefficients in the mixture (i.e. Cl- and NO3-). Decreased flow rate favoured the transport of ions with larger valence numbers and higher electric mobility inside the electrolyte (i.e. SO42-); as the former property governed the faster migration of SO42- ions through the thick boundary layer and the latter property assisted with the improved affinity of the ion-exchange membrane to SO42- ions compared to the monovalent anions in the mixture. Increasing the feed concentration of Cl- from 500 to 2,550 mg/L led to reduced transport numbers for the other anions in the mixture and significantly reducing their removal rate. The results obtained from both the pulsed-ED and wind-ED experiments showed that, despite direct coupling to the fluctuating energy source the SEC of the process remained relatively unaffected by the energy fluctuations. Although the desalination process might require more time to be completed when operating under extreme wind speed fluctuations and intermittencies, the quality of the drinking water produced was always within the WHO standards. In conclusion, the findings from this research prove the wind-ED system to be an energetically robust and a reliable off-grid desalination technique suitable for the treatment of brackish groundwater in water stressed remote regions.