ORCID Profile
0000-0002-4354-0053
Current Organisation
Universiteit Gent
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Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8NJ06160B
Abstract: Silver nanoparticles were synthesized using a greener approach and subsequently embedded on PVDF nanofibre membranes for growth inhibition of mesophilic and thermophilic bacteria.
Publisher: The Electrochemical Society
Date: 09-2016
DOI: 10.1149/MA2016-02/25/1764
Abstract: Introduction Many industrial processes results in the production of complex waste streams, often containing a combination of both organics and inorganics. Ex les can be found in the food industry where for ex le salt is used to treat potatoes, olives, cheese, … RO brines can also contain a mixture of both organics and salts. The treatment of these streams is not straightforward, as the organics limit the applications of common physico-chemical treatment methods (e.g. by fouling of membranes) and the salts h er conventional biological treatment. Furthermore, these conventional techniques are aimed at recovering the water or simply treating the streams before discharge. By selectively separating the organics from the salts, valorisation of both the inorganics (e.g. recycling back to the system) and the organics (e.g. as biogas) can be facilitated. Ion-exchange membranes (IEM) are expected to be a good candidate to achieve this selective separation, since they are less prone to fouling because of the lack of pressure during operation. However, although fouling of IEM has received attention in literature [1–4], the transport mechanics of organics is not well understood yet. In a first study, we showed that the presence of NaCl greatly influences the transport of organics and that this transport seems to be mainly diffusion driven in the presence of salts [5]. This is of great importance not only for the cases described above, but also for other systems that encounter a mixture of organics and inorganics, such as membrane electrolysis and microbial electrosynthesis processes. This study focusses on the effect of different salt types (NaCl, MgCl 2 , Na 2 SO 4 ) and the direction of the transport of the organics relative to the transport of the salts. Both trace organic contaminants (TOrC) and organic acids (OA) are used as a model for organics. Materials and methods A 4-cell pair PC Cell 64004 ED set-up was used for the experiments, equipped with Fujifilm Type I membranes (8x8 cm²). Both experiments with a constant current density and experiments without an external driving force were executed, to distinguish between diffusive and electromigrative transport of the organics. Results Three different hypotheses were tested in this research (1) transport of organics is different in the presence of multivalent salt ions versus monovalent ones, (2) the transport direction of the organics with respect to the salt is important and (3) organics transport is mainly diffusion driven. The tests with multivalent salt ions clearly show that the transport of negatively charged organics is higher in the presence of Na 2 SO 4 and the transport of positively charged organics is higher in the presence of MgCl 2 when compared to NaCl. This can be explained by the lower diffusion coefficient of both SO 4 2- and Mg 2+ compared to Cl - and Na + respectively. When salts and organics are dosed in different compartments, Donnan dialysis plays a significant role in diffusion, causing an increase in the organics transport. This was observed both in experiments with and without an external driving force, further confirming the diffusive nature of the organics transport. This was further endorsed by the experiments with OA, where no difference in transport rate can be observed between experiments with and without external driving force. Furthermore, experiments with OA in the absence of salts show a significantly higher transport rate, both with and without a constant current density. This study confirms the diffusive nature of organics transport in the presence of salts. Ongoing research focusses on the influence of membrane characteristics on the transport behaviour of organics, with the ultimate goal of developing tailor-made membranes for the selective separation between organics and salts. References [1] Bazinet, L. and Araya-Farias, M. (2005) Effect of calcium and carbonate concentrations on cationic membrane fouling during electrodialysis. Journal of Colloid and Interface Science , 281 , 188–96. [2] Banasiak, L.J., Van der Bruggen, B. and Schäfer, A.I. (2011) Sorption of pesticide endosulfan by electrodialysis membranes. Chemical Engineering Journal , 166 , 233–9. [3] Korngold, E., De Körösy, F., Rahav, R. and Taboch, M.F. (1970) Fouling of anionselective membranes in electrodialysis. Desalination , 8 , 195–220. [4] Lindstrand, V., Sundström, G. and Jönsson, A. (2000) Fouling of electrodialysis membranes by organic substances. Desalination , 128 , 91–102. [5] Vanoppen, M., Bakelants, A.F. a M., Gaublomme, D., Schoutteten, K.V.K.M., Bussche, J. Vanden, Vanhaecke, L. et al. (2015) Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes. Environmental Science & Technology , 49 , 489–97.
Publisher: The Electrochemical Society
Date: 09-2016
DOI: 10.1149/MA2016-02/41/3089
Abstract: Introduction Water and energy are two of the main challenges facing our modern world today. With water shortages and pollution reaching alarming levels, research is pushed to look for alternative water sources, such as (secondary treated) waste water and seawater. In the case of seawater, the main issue is the large amount of energy needed for its desalination, around 2-3 kWh/m³ at a recovery of 50% (35 g/l total dissolved solids) in the case of state-of-the-art reverse osmosis (RO). By coupling RO with reverse electrodialysis (RED), the energy demand can be decreased in two ways: (1) energy can be produced in RED by the salinity gradient between the seawater and for ex le impaired water and (2) the concentration of the seawater decreases in RED, entailing a lower energy demand in the RO step. This type of hybrid can theoretically decrease the energy demand of seawater desalination to the point of energy neutrality and can even be energy producing [1,2]. However, the viability of the process is limited by the slow desalination kinetics in RED, resulting in a high required membrane area and consequent high capital costs. The desalination rate in RED is mainly limited in the first stages of desalination, where the low salinity compartment causes a high resistance of both the solution itself and of the membrane. Indeed it was shown that the membrane resistance mainly depends on the low salinity solution it is in contact with [3,4]. Figure 1. Envisioned hybrid (A)RED-RO process To overcome this initially high resistance, a new mode of RED operation was developed: assisted RED or ARED. Here, instead of producing energy, a small potential difference is applied in the same direction as the natural salt transport to increase the desalination rate. ARED can be incorporated into the hybrid system as shown in Figure 1. This study is one of the first to explore the possibilities of ARED on lab-scale. Materials and methods A 5-cell pair RED set-up was used for the ARED tests. Fujifilm type I and type II membranes were used, with an active membrane area of 7.8x11.2 cm². Spacers with a thickness of 485 μm were used to create the low and high salinity compartments. A constant current density (0-136 A/m²) was applied and the resulting voltage was recorded to create current-voltage curves. Experiments were executed in once-through mode to keep the influent concentrations constant. Results To study the influence of the low salinity compartment (impaired water compartment), the seawater compartment concentration was kept constant, at 0.5M NaCl, while the impaired water compartment concentration was varied (0.01, 0.05, 0.1 and 0.25M NaCl). All obtained current-voltage curves at the lower concentrations (0.01 and 0.05M NaCl) show a clear downward declination, indicating a significant decrease in resistance at increasing currents. At lower flow rates, this decrease in resistance becomes more apparent, as the residence time in the system increases. At higher concentrations (0.1 and 0.25M NaCl), the relation is linear, as theoretically expected. The observed decrease in system resistance is caused by an increase in concentration of the low salinity compartment due to the salt transport in the system. Galama et al. (2014) and Geise et al. (2014) showed that the low salinity compartment concentration determines the membrane resistance [3,4] and that an increase in the concentration of this compartment thus leads to a decrease in the membrane resistance as well. The rapid decrease in resistance observed in ARED is its main advantage. By incorporating it into the RED-RO hybrid, it increases the economic viability of the system. Further characterisation and modelling of the system is under way to further assess its value. References [1] Li, W., Krantz, W.B., Cornelissen, E.R., Post, J.W., Verliefde, A.R.D. and Tang, C.Y. (2013) A novel hybrid process of reverse electrodialysis and reverse osmosis for low energy seawater desalination and brine management. Applied Energy , 104 , 592–602. [2] Vanoppen, M., Blandin, G., Derese, S., Le-Clech, P., Post, J.W. and Verliefde, A.R.D. (2016) Salinity gradient power and desalination. In: Cipollina A, and Micale G, editors. Sustainable Energy from Salinity Gradients , 1st ed. Woodhead Publishing-Elsevier, London. p. 281–313. [3] Galama, a. H., Vermaas, D. a., Veerman, J., Saakes, M., Rijnaarts, H.H.M., Post, J.W. et al. (2014) Membrane resistance: The effect of salinity gradients over a cation exchange membrane. Journal of Membrane Science , 467 , 279–91. [4] Geise, M., Curtis, A.J., Hatzell, M.C., Hickner, M.A. and Logan, B.E. (2014) Salt Concentration Differences Alter Membrane Resistance in Reverse Electrodialysis Stacks. Environmental Science & Technology Letters , 1 , 36–9. Figure 1
Publisher: MDPI AG
Date: 07-2016
Abstract: Forward osmosis (FO) is a promising membrane technology to combine seawater desalination and water reuse. More specifically, in a FO-reverse osmosis (RO) hybrid process, high quality water recovered from the wastewater stream is used to dilute seawater before RO treatment. As such, lower desalination energy needs and/or water augmentation can be obtained while delivering safe water for direct potable reuse thanks to the double dense membrane barrier protection. Typically, FO-RO hybrid can be a credible alternative to new desalination facilities or to implementation of stand-alone water reuse schemes. However, apart from the societal (public perception of water reuse for potable application) and water management challenges (proximity of wastewater and desalination plants), FO-RO hybrid has to overcome technical limitation such as low FO permeation flux to become economically attractive. Recent developments (i.e., improved FO membranes, use of pressure assisted osmosis, PAO) demonstrated significant improvement in water flux. However, flux improvement is associated with drawbacks, such as increased fouling behaviour, lower rejection of trace organic compounds (TrOCs) in PAO operation, and limitation in FO membrane mechanical resistance, which need to be better considered. To support successful implementation of FO-RO hybrid in the industry, further work is required regarding up-scaling to apprehend full-scale challenges in term of mass transfer limitation, pressure drop, fouling and cleaning strategies on a module scale. In addition, refined economics assessment is expected to integrate fouling and other maintenance costs/savings of the FO/PAO-RO hybrid systems, as well as cost savings from any treatment step avoided in the water recycling.
Publisher: Wiley
Date: 23-06-2020
DOI: 10.1002/PAT.4986
No related grants have been discovered for Arne Verliefde.