Recent Submissions

  • An improved indirect evaporative cooler experimental investigation

    Shahzad, Muhammad Wakil; Burhan, Muhammad; Ybyraiymkul, Doskhan; Oh, Seung Jin; Ng, Kim Choon (Applied Energy, Elsevier BV, 2019-10-01) [Article]
    Air conditioning has enhanced the work efficiency and improved life style by maintaining comfortable environment. The growing demand of air conditioning has negative impact on energy and environment. In 2015, air conditioning consumed 6% of total global electricity produced and it is expected to increase to 20% by 2050. The leveling-off conventional chiller’s efficiency at 0.85 ± 0.03 kW/Rton due to pairing of dehumidification and cooling processes in one machine is not only the major reason of high energy consumption but also the key limitation in efficiency improvement. The de-coupling of dehumidification and cooling processes can be one of the solution to achieve the quantum jump in the performance, 0.6 ± 0.03 kW/Rton, by improving individual processes. We proposed an improved indirect evaporative cooler system for sensible cooling that can be combined with dehumidification processes to achieve sustainable cooling goals. The experimentation on 800 mm long and 280 mm wide generic cell showed that it can produce temperature differential up to 10 °C with small area of heat transfer. It was showed that the proposed vertical heat exchanger configuration with multi point injection of working air is the best configuration of the indirect evaporative cooler, achieving coefficient of performance level of 78 for cooling alone. We expect that overall coefficient of performance level of 7–8 is achievable by incorporating efficient dehumidification processes. We also presented detailed design parameters that can be used as a reference for commercial system design.
  • 3D Analysis of Ordered Porous Polymeric Particles using Complementary Electron Microscopy Methods

    Alvarez, Juan; Saudino, Giovanni; Musteata, Valentina-Elena; Madhavan, Poornima; Genovese, Alessandro; Behzad, Ali Reza; Sougrat, Rachid; Boi, Cristiana; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira (Scientific Reports, Springer Science and Business Media LLC, 2019-09-27) [Article]
    Highly porous particles with internal triply periodic minimal surfaces were investigated for sorption of proteins. The visualization of the complex ordered morphology requires complementary advanced methods of electron microscopy for 3D imaging, instead of a simple 2D projection: transmission electron microscopy (TEM) tomography, slice-and-view focused ion beam (FIB) and serial block face (SBF) scanning electron microscopy (SEM). The capability of each method of 3D image reconstruction was demonstrated and their potential of application to other synthetic polymeric systems was discussed. TEM has high resolution for details even smaller than 1 nm, but the imaged volume is relatively restricted (2.5 μm)3. The samples are pre-sliced in an ultramicrotome. FIB and SBF are coupled to a SEM. The sample sectioning is done in situ, respectively by an ion beam or an ultramicrotome, SBF, a method so far mostly applied only to biological systems, was particularly highly informative to reproduce the ordered morphology of block copolymer particles with 32-54 nm nanopores and sampling volume (20 μm)3.
  • Identification and characterization of core sludge and biofilm microbiota in anaerobic membrane bioreactors

    Cheng, Hong; Cheng, Dan; Mao, Junwen; Lu, Ting; Hong, Pei-Ying (Environment International, Elsevier BV, 2019-09-11) [Article]
    An analysis of sludge (i.e., 63 samples) and biofilm (i.e., 79 samples) sampled from 13 anaerobic membrane bioreactors (AnMBR) was conducted. Predominant microbial community identification and multivariate analysis indicate that these reactors showed different microbial community structure, but these differences had no impact on the overall AnMBR performance. Instead, core microbial genera which occurred in ≥90% of sludge (20 genera) and biofilm (12 genera) samples could potentially account for the AnMBR performance. A further calculation on net growth rate (NGR) of core genera in sludge suggested distribution into two main groups (i.e., I: low relative abundance and NGR, II: high relative abundance or high NGR). Consistent positive correlations between bacterial genera were observed among those that exhibited either high relative abundance or high NGR. The anaerobic microbial consortium in both sludge and biofilm were largely affected by stochastic dispersal and migration processes (i.e., neutral assembly). However, Acinetobacter spp. and Methanobacterium spp. occurred consistently in higher frequency in the biofilm but in lower occurrence frequency in the AnMBR permeate. Findings from this study suggest first, specific core microorganisms exist in the sludge regardless of the operating conditions of the AnMBRs, and second, prevention of biofoulant layer on anaerobic membranes can be devised by minimizing attachment of microbes on surfaces in a non-selective manner.
  • Pilot-Scale Assessment of Urea as a Chemical Cleaning Agent for Biofouling Control in Spiral-Wound Reverse Osmosis Membrane Elements.

    Sanawar, Huma; Bucs, Szilárd S; Pot, Martin A; Zlopasa, Jure; Farhat, Nadia; Witkamp, Geert Jan; Kruithof, Joop C; van Loosdrecht, Mark C M; Vrouwenvelder, Johannes S. (Membranes, MDPI AG, 2019-09-11) [Article]
    Routine chemical cleaning with the combined use of sodium hydroxide (NaOH) and hydrochloric acid (HCl) is carried out as a means of biofouling control in reverse osmosis (RO) membranes. The novelty of the research presented herein is in the application of urea, instead of NaOH, as a chemical cleaning agent to full-scale spiral-wound RO membrane elements. A comparative study was carried out at a pilot-scale facility at the Evides Industriewater DECO water treatment plant in the Netherlands. Three fouled 8-inch diameter membrane modules were harvested from the lead position of one of the full-scale RO units treating membrane bioreactor (MBR) permeate. One membrane module was not cleaned and was assessed as the control. The second membrane module was cleaned by the standard alkali/acid cleaning protocol. The third membrane module was cleaned with concentrated urea solution followed by acid rinse. The results showed that urea cleaning is as effective as the conventional chemical cleaning with regards to restoring the normalized feed channel pressure drop, and more effective in terms of (i) improving membrane permeability, and (ii) solubilizing organic foulants and the subsequent removal of the surface fouling layer. Higher biomass removal by urea cleaning was also indicated by the fact that the total organic carbon (TOC) content in the HCl rinse solution post-urea-cleaning was an order of magnitude greater than in the HCl rinse after standard cleaning. Further optimization of urea-based membrane cleaning protocols and urea recovery and/or waste treatment methods is proposed for full-scale applications.
  • Membrane-Free Detection of Metal Cations with an Organic Electrochemical Transistor

    Wustoni, Shofarul; Combe, Craig; ohayon, David; Akhtar, Mahmood Hassan; McCulloch, Iain; Inal, Sahika (Advanced Functional Materials, Wiley, 2019-08-26) [Article]
    Alkali-metal ions, particularly sodium (Na+) and potassium (K+), are the messengers of living cells, governing a cascade of physiological processes through the action of ion channels. Devices that can monitor, in real time, the concentrations of these cations in aqueous media are in demand not only for the study of cellular machinery, but also to detect conditions in the human body that lead to electrolyte imbalance. In this work, conducting polymers are developed that respond rapidly and selectively to varying concentrations of Na+ and K+ in aqueous media. These polymer films, bearing crown-ether-functionalized thiophene units specific to either Na+ or K+, generate an electrical output proportional to the cation type and concentration. Using electropolymerization, the ion-selective polymers are integrated as the gate electrode of an organic electrochemical transistor (OECT). The OECT current changes with respect to the concentration of the ion to which the polymer electrode is selective. Designed as a single, miniaturized chip, the OECT enables the selective detection of the cations within a physiologically relevant range. These electrochemical ion sensors require neither ion-selective membranes nor a reference electrode to operate and have the potential to surpass existing technologies for the detection of alkali-metal ions in aqueous media.
  • An organic electrochemical transistor integrated with a molecularly selective isoporous membrane for amyloid-β detection.

    Wustoni, Shofarul; Wang, Shaofei; Alvarez, Juan R; Hidalgo, Tania C; Nunes, Suzana Pereira; Inal, Sahika (Biosensors & bioelectronics, Elsevier BV, 2019-08-26) [Article]
    Alzheimer's disease (AD) is a progressive neurodegenerative disease associated with severe memory loss and impaired cognitive skills. A common pathological change found in AD-affected brains is the accumulation of a peptide named amyloid-β (Aβ) that can form plaques. Aβ aggregates are visible to structural scanning tools; however, these bulky and expensive instruments are accessible to trained personnel in clinical settings only, thus hampering timely diagnosis of the disease, particularly in low-resource settings. In this work, we design an organic electrochemical transistor (OECT) for in vitro detection of Aβ aggregates in human serum. The OECT channel is integrated with a nanostructured isoporous membrane which has a strong affinity for Aβ aggregates. The detection mechanism relies on the membrane capturing Aβ aggregates larger than the size of its pores and thus blocking the penetration of electrolyte ions into the channel underneath. Combining the high transconductance of the OECT with the precise porosity and selectivity of the membrane, the device detects the presence of Aβ aggregates in human serum samples with excellent sensitivity. This is the first-time demonstration of a biofunctionalized, nanostructured, and isoporous membrane integrated with a high-performance transistor for biosensing. This robust, low-power, non-invasive, and miniaturized sensor aids in the development of point-of-care tools for early diagnosis of AD.
  • The past, present, and future of coral heat stress studies

    Cziesielski, Maha Joana; Schmidt-Roach, Sebastian; Aranda, Manuel (Ecology and Evolution, Wiley, 2019-08-22) [Article]
    The global loss and degradation of coral reefs, as a result of intensified frequency and severity of bleaching events, is a major concern. Evidence of heat stress affecting corals through loss of symbionts and consequent coral bleaching was first reported in the 1930s. However, it was not until the 1998 major global bleaching event that the urgency for heat stress studies became internationally recognized. Current efforts focus not only on examining the consequences of heat stress on corals but also on finding strategies to potentially improve thermal tolerance and aid coral reefs survival in future climate scenarios. Although initial studies were limited in comparison with modern technological tools, they provided the foundation for many of today's research methods and hypotheses. Technological advancements are providing new research prospects at a rapid pace. Understanding how coral heat stress studies have evolved is important for the critical assessment of their progress. This review summarizes the development of the field to date and assesses avenues for future research.
  • Evidence of Spatial Homogeneity in an Electromethanogenic Cathodic Microbial Community.

    Ragab, Alaa I.; Katuri, Krishna; Ali, Muhammad; Saikaly, Pascal E (Frontiers in microbiology, Frontiers Media SA, 2019-08-17) [Article]
    Microbial electrosynthesis (MES) has been gaining considerable interest as the next step in the evolution of microbial electrochemical technologies. Understanding the niche biocathode environment and microbial community is critical for further developing this technology as the biocathode is key to product formation and efficiency. MES is generally operated to enrich a specific functional group (e.g., methanogens or homoacetogens) from a mixed-culture inoculum. However, due to differences in H2 and CO2 availability across the cathode surface, competition and syntrophy may lead to overall variability and significant beta-diversity within and between replicate reactors, which can affect performance reproducibility. Therefore, this study aimed to investigate the distribution and potential spatial variability of the microbial communities in MES methanogenic biocathodes. Triplicate methanogenic biocathodes were enriched in microbial electrolysis cells for 5 months at an applied voltage of 0.7 V. They were then transferred to triplicate dual-chambered MES reactors and operated at -1.0 V vs. Ag/AgCl for six batches. At the end of the experiment, triplicate samples were taken at different positions (top, center, bottom) from each biocathode for a total of nine samples for total biomass protein analysis and 16S rRNA gene amplicon sequencing. Microbial community analyses showed that the biocathodes were highly enriched with methanogens, especially the hydrogenotrophic methanogen family Methanobacteriaceae, Methanobacterium sp., and the mixotrophic Methanosarcina sp., with an overall core community representing > 97% of sequence reads in all samples. There was no statistically significant spatial variability (p > 0.05) observed in the distribution of these communities within and between the reactors. These results suggest deterministic community assembly and indicate the reproducibility of electromethanogenic biocathode communities, with implications for larger-scale reactors.
  • Elucidation of dual-mode inhibition mechanism of a typical polymer-based antiscalant on Red seawater for thermal desalination at higher temperatures and higher concentration factors

    Singh, Yogesh Balwant; Ng, Kim Choon (Journal of Petroleum Science and Engineering, Elsevier B.V., 2019-08-16) [Article]
    Scale deposition in the thermal process for desalination is quite inevitable. This study is about scale formation, crystal modification, and prevention mechanism of a tetrapolymer based antiscalant on Red Seawater. Red seawater at concentration factors (CF) of 1.5 and 2.5 was studied under reflux condition at 70 °C and 98 °C respectively for seven hours with 1 ppm, 2 ppm, and 4 ppm concentration of the antiscalant. Eventually, the mechanism of inhibitory action of the antiscalant has been reconnoitered after seawater analysis and imaging the morphological changes in the crystal formation patterns with Scanning electron microscope (SEM). The changes in the values of pH, turbidity and alkalinity (both phenolphthalein alkalinity (PA) and total alkalinity (TA)) were measured to apprehend various fluctuations happening as a result of the addition of antiscalant. The variations in the pH of seawater with antiscalant were in concurrence with the changes in alkalinity and was also reflected in turbidity. These changes explicitly demonstrated the threshold mechanism of scale inhibition. SEM micrographs exhibited distorted round shaped depositions supporting crystal modification mechanism as well. The efficiency and dominance of inhibitory mechanism varied from 2 h to 6 h for the antiscalant and was observed to be directly related to CF of seawater used, the temperature applied, and a dose of antiscalant added.
  • Membrane distillation hybrids for water production and energy efficiency enhancement: A critical review

    Ghaffour, NorEddine; Soukane, S.; Lee, Jung Gil; Kim, Y.; Alpatova, Alla (Applied Energy, Elsevier BV, 2019-08-13) [Article]
    With an ever-increasing demand in energy, constrained by strict environmental regulations, process development faces stringent design requirements further limited by intrinsic properties of inherent materials. Process hybridization is now considered as an improvement path to several limitations. Complementarity between processes is the essence of the hybridization concept, with the ultimate goal to design more eco-friendly, energy efficient process combinations delivering higher throughputs and boosting the thermodynamic limits of the existing mature technologies. Market size of membrane-based separation processes, widely used in desalination, water treatment and purification, is forecasted to grow significantly in the next decades. While desalination market is mainly shared between thermal processes and reverse osmosis (RO), advanced water treatment and purification rely mostly on membrane technology. Among the large span of available techniques stands membrane distillation (MD), to which a tremendous research effort has been dedicated during the last two decades. Although praised for its numerous advantages, this thermally-driven separation process still cannot withstand large production rates while maintaining energy efficiency. Hybridization of MD with existing technologies and other emerging processes is therefore at the leading edge. This literature review presents the state-of-the-art MD hybrids with different separation processes including RO, pressure retarded osmosis, forward osmosis, mechanical vapor compression, electrocoagulation, electrodialysis, multi-stage flash, multi-effect distillation, crystallization and adsorption with a focus on water production and energy efficiency enhancement. Each of these processes has advantages at the cost of more or less severe drawbacks and its association to MD offers improvement opportunities. Each variant is thoroughly reviewed with major contributions and knowledge gaps highlighted. Perspectives and recommendations are emphasized in each case. Latest developments in MD and its energy consumption and optimization are also reported.
  • Membrane backwash cleaning using CO2 nucleation

    Al Ghamdi, Mohanned; Alhadidi, Abdulsalam; Ghaffour, NorEddine (Water Research, Elsevier BV, 2019-08-13) [Article]
    Low pressure membranes, such as ultrafiltration (UF), are widely used in water treatment applications, including the pretreatment of reverse osmosis desalination. UF membranes produce a water of superior quality, in addition to reducing the footprint and the use of chemicals, compared to conventional methods. However, membrane fouling remains a major drawback, and frequent membrane cleanings are required to maintain the flux of water and its quality. Typically, after a series of backwashes using an UF permeate, a chemical cleaning process is applied to fully recover the membrane's permeability. However, frequent chemical cleanings negatively affect the lifetime of the membrane, the environment, and increase operational costs. Here, we introduce a novel cleaning method that uses a solution saturated with CO2 to clean the membranes through the backwash step. As the pressure drops, the CO2 solution becomes supersaturated, and bubbles start to nucleate within the membrane pores and on its surface, resulting in the effective removal of the deposited fouling material. These foulants are further helping the nucleation process as they are considered as imperfection sites with high creation and growth of bubbles. Investigations performed for different synthetic feed solutions of organic compounds (sodium alginate), colloidal matter (silica) and sea salts, at different concentrations, show that our new physical cleaning process using CO2 is more performant than the regular backwash using Milli-Q water. We obtain a 100% flux recovery, in a short time, even under severe irreversible fouling conditions. Based on these results, we conclude that replacing water by a solution saturated with CO2 for the backwash cleaning of filtration membranes provides significant benefits to existing cleaning processes, and represent a promising alternative for improving and lowering the frequency of conventional chemical cleaning methods.
  • Predicting the performance of large-scale forward osmosis module using spatial variation model: Effect of operating parameters including temperature

    Lee, Jung Gil; Ghaffour, NorEddine (Desalination, Elsevier BV, 2019-08-12) [Article]
    Forward osmosis (FO) is considered as an energy-efficient process for numerous applications. Although its performance is determined by the spatially varied operation factors and the length of the channel, most of the reported simulation studies rely on length-averaged lumped models. Here, we introduce a one-D model based on heat and mass transfer and transport behavior for both bulk draw and feed channel flows. We find prediction results to be in good agreement with two different experimental results at inlet feed temperatures below 25 °C. However, the difference of water flux (Jw) and reverse salt flux (RSF) between measured and predicted data increases when both feed and draw temperatures also increase. Our theoretical simulation study first reveals that the feed temperature near the membrane active layer surface is the main factor for improving water and salt permeabilities. We find that, with a channel width of 0.3 m and a channel length of 2.5 m, Jw and RSF calculated using the length-averaged based lumped model are overestimated by 13.01% and 13.12%, respectively, compared to those obtained using our new spatial variation model. Our study demonstrates that the length-averaged based lumped model is not an appropriate simulation model to predict the performance of large-scale FO modules at lower inlet velocities.
  • Energy efficient 3D printed column type feed spacer for membrane filtration

    Ali, Syed Muztuza; Qamar, Adnan; Kerdi, Sarah; Phuntsho, S.; Vrouwenvelder, Johannes S.; Ghaffour, NorEddine; Shon, H.K. (Water Research, Elsevier BV, 2019-08-06) [Article]
    Modification of the feed spacer design significantly influences the energy consumption of membrane filtration processes. This study developed a novel column type feed spacer with the aim to reduce the specific energy consumption (SEC) of the membrane based water filtration system. The proposed spacer increases the clearance between the filament and the membrane (reducing the spacer filament diameter) while keeping the same flow channel thickness as compared to a standard non-woven symmetric spacer. Since the higher clearance reduces the flow unsteadiness, column type nodes were added in the spacer structure as additional vortex shading bodies. Fluid flow behaviour in the channel for this spacer was numerically simulated by 3D CFD studies and then compared with the standard spacer. The numerical results showed that the proposed spacer substantially reduced the pressure drop, shear stress at the constriction region and shortened the dead zone. Finally, these findings were confirmed experimentally by investigating the filtration performances using the 3D printed prototypes of these spacers in a lab-scale filtration module. It is observed that the column spacer reduced the pressure drop by three times and doubled the specific water flux. 2D OCT (Optical Coherence Tomography) scans of the membrane surface acquired after the filtration revealed much lower biomass accumulation using the proposed spacer. Consequently, the SEC for the column spacer was found about two folds lower than the standard spacer.
  • Nuclear Quantum Effects in Hydrophobic Nanoconfinement.

    Shrestha, Buddha Ratna; Pillai, Sreekiran; Santana, Adriano; Donaldson, Stephen H; Pascal, Tod A; Mishra, Himanshu (The journal of physical chemistry letters, American Chemical Society (ACS), 2019-08-01) [Article]
    Nuclear quantum effects (NQEs) in water arise due to delocalization, zero-point energy (ZPE), and quantum tunneling of protons. Whereas quantum tunneling is significant only at low temperatures, proton delocalization and ZPE influence the properties of water at normal temperature and pressure (NTP), giving rise to isotope effects. However, the consequences of NQEs for interfaces of water with hydrophobic media, such as perfluorocarbons, have remained largely unexplored. Here, we reveal the existence and signature of NQEs modulating hydrophobic surface forces at NTP. Our experiments demonstrate that the attractive hydrophobic forces between molecularly smooth and rigid perfluorinated surfaces in nanoconfinement are ≈10% higher in H2O than in D2O, even though the contact angles of H2O and D2O on these surfaces are indistinguishable. Our molecular dynamics simulations show that the underlying cause of the difference includes the destabilizing effect of ZPE on the librational motions of interfacial H2O, which experiences larger quantum effects than D2O.
  • Global spatial risk assessment of sharks under the footprint of fisheries.

    Queiroz, Nuno; Humphries, Nicolas E; Couto, Ana; Vedor, Marisa; da Costa, Ivo; Sequeira, Ana M M; Mucientes, Gonzalo; Santos, António M; Abascal, Francisco J; Abercrombie, Debra L; Abrantes, Katya; Acuña-Marrero, David; Afonso, André S; Afonso, Pedro; Anders, Darrell; Araujo, Gonzalo; Arauz, Randall; Bach, Pascal; Barnett, Adam; Bernal, Diego; Berumen, Michael L.; Lion, Sandra Bessudo; Bezerra, Natalia P A; Blaison, Antonin V; Block, Barbara A; Bond, Mark E; Bradford, Russell W; Braun, Camrin D; Brooks, Edward J; Brooks, Annabelle; Brown, Judith; Bruce, Barry D; Byrne, Michael E; Campana, Steven E; Carlisle, Aaron B; Chapman, Demian D; Chapple, Taylor K; Chisholm, John; Clarke, Christopher R; Clua, Eric G; Cochran, Jesse E M; Crochelet, Estelle C; Dagorn, Laurent; Daly, Ryan; Cortés, Daniel Devia; Doyle, Thomas K; Drew, Michael; Duffy, Clinton A J; Erikson, Thor; Espinoza, Eduardo; Ferreira, Luciana C; Ferretti, Francesco; Filmalter, John D; Fischer, G Chris; Fitzpatrick, Richard; Fontes, Jorge; Forget, Fabien; Fowler, Mark; Francis, Malcolm P; Gallagher, Austin J; Gennari, Enrico; Goldsworthy, Simon D; Gollock, Matthew J; Green, Jonathan R; Gustafson, Johan A; Guttridge, Tristan L; Guzman, Hector M; Hammerschlag, Neil; Harman, Luke; Hazin, Fábio H V; Heard, Matthew; Hearn, Alex R; Holdsworth, John C; Holmes, Bonnie J; Howey, Lucy A; Hoyos, Mauricio; Hueter, Robert E; Hussey, Nigel E; Huveneers, Charlie; Irion, Dylan T; Jacoby, David M P; Jewell, Oliver J D; Johnson, Ryan; Jordan, Lance K B; Jorgensen, Salvador J; Joyce, Warren; Daly, Clare A Keating; Ketchum, James T; Klimley, A Peter; Kock, Alison A; Koen, Pieter; Ladino, Felipe; Lana, Fernanda O; Lea, James S E; Llewellyn, Fiona; Lyon, Warrick S; MacDonnell, Anna; Macena, Bruno C L; Marshall, Heather; McAllister, Jaime D; McAuley, Rory; Meÿer, Michael A; Morris, John J; Nelson, Emily R; Papastamatiou, Yannis P; Patterson, Toby A; Peñaherrera-Palma, Cesar; Pepperell, Julian G; Pierce, Simon J; Poisson, Francois; Quintero, Lina Maria; Richardson, Andrew J; Rogers, Paul J; Rohner, Christoph A; Rowat, David R L; Samoilys, Melita; Semmens, Jayson M; Sheaves, Marcus; Shillinger, George; Shivji, Mahmood; Singh, Sarika; Skomal, Gregory B; Smale, Malcolm J; Snyders, Laurenne B; Soler, German; Soria, Marc; Stehfest, Kilian M; Stevens, John D; Thorrold, Simon R; Tolotti, Mariana T; Towner, Alison; Travassos, Paulo; Tyminski, John P; Vandeperre, Frederic; Vaudo, Jeremy J; Watanabe, Yuuki Y; Weber, Sam B; Wetherbee, Bradley M; White, Timothy D; Williams, Sean; Zárate, Patricia M; Harcourt, Robert; Hays, Graeme C; Meekan, Mark G; Thums, Michele; Irigoien, Xabier; Eguiluz, Victor M; Duarte, Carlos M.; Sousa, Lara L; Simpson, Samantha J; Southall, Emily J; Sims, David W (Nature, Springer Science and Business Media LLC, 2019-07-25) [Article]
    Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management.
  • Reply to the ‘Comment on “The chemical reactions in electrosprays of water do not always correspond to those at the pristine air–water interface”’ by A. J. Colussi and S. Enami, Chem. Sci., 2019, 10, DOI: 10.1039/c9sc00991d

    Gallo Junior, Adair; Farinha, Andreia S. F.; Emwas, Abdul-Hamid M.; Santana, Adriano; Nielsen, Robert J.; Goddard, William A.; Mishra, Himanshu (Chemical Science, Royal Society of Chemistry (RSC), 2019-07-23) [Article]
    The air–water interface serves as a crucial site for numerous chemical and physical processes in environmental science and engineering, such as cloud chemistry, ocean-atmosphere exchange, and wastewater treatment. The development of “surface-selective” techniques for probing interfacial properties of water therefore lies at the forefront of research in chemical science. Recently, researchers have adapted electrospray ionization mass spectrometry (ESIMS) to generate microdroplets of water to investigate interfacial phenomena at thermodynamic equilibrium. In contrast, using a broad set of experimental and theoretical techniques, we found that electrosprays of water could facilitate partially hydrated (gas-phase) ions (e.g., H3O+·(H2O)2) to drive/catalyze chemical reactions that are otherwise not possible to accomplish by purely interfacial effects (e.g., enhanced water–hydrophobe surface area) (Chem. Sci., 2019, 10, 2566). Thus, techniques exploiting electrosprays of water cannot be relied upon as generalized surface-selective platforms. Here, we respond to the comments raised by Colussi & Enami (Chem. Sci., 2019, 10, DOI: 10.1039/c9sc00991d) on our paper.
  • Recycled Poly(ethylene terephthalate) for High Temperature Solvent Resistant Membranes

    Pulido, Bruno; Habboub, Ola; Aristizabal, Sandra; Szekely, Gyorgy; Nunes, Suzana Pereira (ACS Applied Polymer Materials, American Chemical Society (ACS), 2019-07-22) [Article]
    Porous membranes of recycled poly(ethylene terephthalate) (PET) were prepared by non-solvent induced phase separation (NIPS) and evaluated for the first time for the filtration in high temperature solvents and other harsh environments. The PET was recycled from commercial water bottles. The morphology, pore size and pore density were optimized by varying the composition of the polymer concentration in the casting solution, the solvent, and the non-solvent bath in conditions of controlled humidity and temperature. Poly(ethylene glycol) (PEG) of 0.2 and 1 kg mol-1 was used as an additive and pore inducing agent. The filtration performance of the membranes was tested under different solvents and temperatures. The obtained PET membranes were successfully applied for ultrafiltration with a MWCO of 40 kg mol-1 in dimethylformamide (DMF) at temperatures up to 100 ˚C. PET membranes were found to be resistant to a wide variety of solvents as well as in chlorine and acid medium. They could be used as porous support for thin-film composite membranes and for different applications requiring high chemical and heat resistance.
  • Hydrodynamic flow transition dynamics in a spacer filled filtration channel using direct numerical simulation

    Qamar, Adnan; Bucs,Szilard; Picioreanu, Cristian; Vrouwenvelder, Johannes S.; Ghaffour, Noreddine (Journal of Membrane Science, Elsevier BV, 2019-07-19) [Article]
    A vital component of spiral-wound membrane modules is the spacer mesh. It not only structurally supports the membranes but also aids in mass-transport enhancement through the membrane surface. Fundamental understanding of hydrodynamics associated with these spacer designs is critical to improve the permeate flux performance by decreasing concentration polarization and minimizing (bio)fouling, as well as minimizing the axial pressure drop. In the present study, time and space resolved Direct Numerical Simulations (DNS) were performed for a commercial spacer geometry. The spacer geometry was reconstructed by measurements using Scanning Electron Microscopy (SEM). Computations were performed for three spacer cells, allowing elimination of stream-wise periodicity that was a major bottleneck in earlier studies. The numerical solver was well checked in terms of boundary layer profiles obtained from Particle Image Velocimetry (PIV) data and with pressure measurements corresponding to various flow channel velocities. Non-dimensional computations were performed for Reynolds Numbers (Re) ranging from 73 to 375 (inlet channel velocity of 0.073–0.375 m/s) covering the flow transition dynamics regime. Results indicate that flow transition from steady to unsteady regime occurs for Re > 250. The flow transition could be primarily attributed to the interaction between vortices attached to the spacer filaments and the screw-vortex that originates along the diagonal of the spacer cells. No turbulent transition was observed even at the highest investigated velocity (Re = 375). The frequency spectra of time-varying velocity signal shows that at Re > 350 a sudden shift of frequency spectra occurs from discrete to continuous mode indicating the onset of advanced instability. Spacer design criteria in terms of maximum principal stress is also proposed, which can potentially aid in minimizing biofilm seeding.
  • Enhanced ammonia recovery from wastewater by Nafion membrane with highly porous honeycomb nanostructure and its mechanism in membrane distillation

    Guo, Jiaxin; Lee, Jung Gil; Tan, Tian; Yeo, Joonho; Wong, Pak Wai; Ghaffour, Noreddine; An, Alicia Kyoungjin (Journal of Membrane Science, Elsevier BV, 2019-07-17) [Article]
    Removing nitrogen from wastewater by conventional treatment methods requires substantial energy, only to release it back to the atmosphere as gaseous nitrogen. Herein, we investigated the applicability of membrane distillation (MD) in resource recovery from sludge digestate by controlling the volatility and pressure of the vapor transport across the membrane to concentrate ammonia in the permeate stream. A mixture of Nafion ionomer and Multiwall Carbon Nanotubes (MWCNTs) were incorporated into a Poly (vinylidene fluoride-co-hexafluoropropene; PVDF-HFP) nanofiber matrix to fabricate a nanoporous honeycomb Nafion membrane featuring high recovery and increased mechanical strength. Theoretical modeling was conducted to predict the expected performance of the fabricated Nafion membrane under different operation conditions and to reveal the mechanism behind the enhanced recovery of Nafion membranes in the MD process. The resultant Nafion (8%)/MWCNT (2.5%)/PVDF-HFP nanofibrous membrane showed up to three times higher ammonia recovery compared to the commercial PVDF membrane from a feed with an ammonia concentration of 300 mg/L. The theoretical analysis quantitatively revealed that the Nafion containing membrane can not only suppress the negative effect of membrane's structural resistance on the ammonia recovery efficiency but also enhance the efficiency. In addition, we also uncovered that the effect of Nafion on ammonia recovery efficiency was maximized when the Nafion 8% membrane was employed. This study demonstrated an innovative and realistically applicable MD treatment process for recovering resource, which integrates low-grade heat and has scaling-up potential for wastewater treatment plants.
  • Removal and biotransformation pathway of antibiotic sulfamethoxazole from municipal wastewater treatment by anaerobic membrane bioreactor

    Wei, Chunhai; Sanchez Huerta, Claudia; Leiknes, TorOve; Amy, Gary L.; Zhou, Hong; Hu, Xiaodong; Fang, Qian; Rong, Hongwei (Journal of Hazardous Materials, Elsevier B.V., 2019-07-15) [Article]
    A lab-scale mesophilic anaerobic membrane bioreactor (AnMBR) was used to treat synthetic municipal wastewater with variable concentrations of antibiotic Sulfamethoxazole (SMX) and bulk organics in this study. The removal and biotransformation pathway of SMX in the AnMBR were systematically investigated during a 170 d of operation under hydraulic retention time of 1 d. Average SMX removal was 97.1% under feed SMX of 10–1000 μg/L, decreasing to 91.6 and 88.0% under feed SMX of 10,000 and 100,000 μg/L due to the inhibition effects of high SMX loading rate on anaerobic microorganisms. SMX biotransformation followed pseudo-first order reaction kinetics based on SMX removal independent of feed SMX of 10–1000 μg/L during continuous operation and also in a batch test under initial SMX of 100,000 μg/L. According to the identified 7 transformation products (TPs) by gas chromatography-mass spectrometry, the biotransformation pathway of SMX from municipal wastewater treatment via AnMBR was first proposed to consist of 2 primary routes: 1) Butylbenzenesulfonamide without antibiotic toxicity dominated under feed SMX of 10–100 μg/L; 2) Sulfanilamide with much lower antibiotic toxicity than SMX dominated under feed SMX of 1000–100000 μg/L, further transforming to secondary TPs (4-Aminothiophenol, Aniline, Acetylsulfanilamide) and tertiary TPs (4-Acetylaminothiophenol, Acetylaniline).

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