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Recent Submissions

  • Characterization of microbiologically influenced corrosion by comprehensive metagenomic analysis of an inland oil field.

    Nasser, Badoor Ali Hassan; Saito, Yoshimoto; Alarawi, Mohammed; Humam, Abdulmohsen A; Mineta, Katsuhiko; Gojobori, Takashi (Gene, Elsevier BV, 2021-01-15) [Article]
    Corrosion in pipelines and reservoir tanks in oil plants is a serious problem in the global energy industry because it causes substantial economic losses associated with frequent part replacement and can lead to potential damage to entire crude oil fields. Previous studies revealed that corrosion is mainly caused by microbial activities in a process currently termed microbiologically influenced corrosion (MIC) or biocorrosion. Identifying the bacteria responsible for biocorrosion is crucial for its suppression. In this study, we analyzed the microbial communities present at corrosion sites in oil plant pipelines using comparative metagenomic analysis along with bioinformatics and statistics. We analyzed the microbial communities in pipelines in an oil field in which groundwater is used as injection water. We collected samples from four different facilities in the oil field. Metagenomic analysis revealed that the microbial community structures greatly differed even among samples from the same facility. Treatments such as biocide administration and demineralization at each location in the pipeline may have independently affected the microbial community structure. The results indicated that microbial inspection throughout the pipeline network is essential to prevent biocorrosion at industrial plants. By identifying the bacterial species responsible for biocorrosion, this study provides bacterial indicators to detect and classify biocorrosion. Furthermore, these species may serve as biomarkers to detect biocorrosion at an early stage. Then, appropriate management such as treatment with suitable biocides can be performed immediately and appropriately. Thus, our study will serve as a platform for obtaining microbial information related to biocorrosion to enable the development of a practical approach to prevent its occurrence.
  • Characterization of microbiologically influenced corrosion by comprehensive metagenomic analysis of an inland oil field.

    Nasser, Badoor Ali Hassan; Saito, Yoshimoto; Alarawi, Mohammed; Humam, Abdulmohsen A; Mineta, Katsuhiko; Gojobori, Takashi (Gene, Elsevier BV, 2021-01-15) [Article]
    Corrosion in pipelines and reservoir tanks in oil plants is a serious problem in the global energy industry because it causes substantial economic losses associated with frequent part replacement and can lead to potential damage to entire crude oil fields. Previous studies revealed that corrosion is mainly caused by microbial activities in a process currently termed microbiologically influenced corrosion (MIC) or biocorrosion. Identifying the bacteria responsible for biocorrosion is crucial for its suppression. In this study, we analyzed the microbial communities present at corrosion sites in oil plant pipelines using comparative metagenomic analysis along with bioinformatics and statistics. We analyzed the microbial communities in pipelines in an oil field in which groundwater is used as injection water. We collected samples from four different facilities in the oil field. Metagenomic analysis revealed that the microbial community structures greatly differed even among samples from the same facility. Treatments such as biocide administration and demineralization at each location in the pipeline may have independently affected the microbial community structure. The results indicated that microbial inspection throughout the pipeline network is essential to prevent biocorrosion at industrial plants. By identifying the bacterial species responsible for biocorrosion, this study provides bacterial indicators to detect and classify biocorrosion. Furthermore, these species may serve as biomarkers to detect biocorrosion at an early stage. Then, appropriate management such as treatment with suitable biocides can be performed immediately and appropriately. Thus, our study will serve as a platform for obtaining microbial information related to biocorrosion to enable the development of a practical approach to prevent its occurrence.
  • A first-principles approach for treating wastewaters

    Santana, Adriano; Farinha, Andreia S. F.; Zarzar Torano, Aniela; Ibrahim, Mahmoud; Mishra, Himanshu (International Journal of Quantum Chemistry, Wiley, 2021-01-15) [Article]
    Numerous materials are employed for the removal of contaminants from wastewaters. However, the regeneration/reuse of these materials is still seldom practiced. Quantitative insights into intermolecular forces between the contaminants and the functional surfaces might aid the rational design of reusable materials. Here, we compare the efficacies of aliphatic (C8H18), aromatic (C6H6), and aromatic perfluorinated (C6F6) moieties at removing methylene blue (MB+) as a surrogate cationic dye from water. We employed density functional theory with an implicit polarizable continuum model for water to accurately determine the contributions of the solvent's electrostatics in the adsorption process. Our calculations pinpointed the relative contributions of ππ stacking, van der Waals complexation, hydrogen bonding, and cationπ interactions, predicting that MB+ would bind the strongest with C6F6 due to hydrogen bonding and the weakest with C8H18. Complementary laboratory experiments revealed that, despite the similar hydrophobicity of silica beads functionalized with SiC8H17, SiC6H5, and SiC6F5 groups, as characterized by their water contact angles, the relative uptake of aqueous MB+ varied as SiC6F5 (95%) > SiC6H5 (35%) > SiC8H17 (3%). This first principles-led experimental approach can be easily extended to other classes of dyes, thereby advancing the rational design of adsorbents.
  • A zero liquid discharge system integrating multi-effect distillation and evaporative crystallization for desalination brine treatment

    Chen, Qian; Burhan, Muhammad; Shahzad, Muhammad Wakil; Ybyraiymkul, Doskhan; Akhtar, Faheem; Li, Yong; Ng, Kim Choon (Desalination, Elsevier BV, 2021-01-13) [Article]
    With growing global desalination capacity, brine from desalination plants has become an environmental threat to the ecosystems. One sustainable method for brine treatment is to develop zero liquid discharge systems that completely convert seawater into freshwater and salts. This paper presents a zero liquid discharge system, which consists of multi-effect distillation and evaporative crystallization, to treat desalination brine with a salinity of 70 g/kg. A thermodynamic analysis is firstly conducted for the proposed system. The specific heat consumption, specific heat transfer area, and Second-law efficiency are found to be 600–1100 kJ/kg, 110–340 m2/(kg/s), and 10–17%, respectively. The heat consumption can be effectively reduced by increasing the number of MED stages, while the specific heat transfer area decreases significantly with higher heat source temperatures. Based on the thermodynamic performance, a techno-economic analysis is conducted for the proposed system, and the specific cost is calculated to be $4.17/m3. Cost reduction can be achieved via employing cost-effective heat sources, reducing heat consumption, and scaling up the system. By selling the freshwater and salt crystals, the system will be more competitive than other existing brine treatment methods.
  • Elucidating the Role of Virulence Traits in the Survival of Pathogenic E. coli PI-7 Following Disinfection

    Sivakumar, Krishnakumar; Lehmann, Robert; Rachmadi, Andri Taruna; Augsburger, Nicolas; Zaouri, Noor A.; Tegner, Jesper; Hong, Pei-Ying (Frontiers in bioengineering and biotechnology, Frontiers Media SA, 2021-01-08) [Article]
    Reuse and discharge of treated wastewater can result in dissemination of microorganisms into the environment. Deployment of disinfection strategies is typically proposed as a last stage remediation effort to further inactivate viable microorganisms. In this study, we hypothesize that virulence traits, including biofilm formation, motility, siderophore, and curli production along with the capability to internalize into mammalian cells play a role in survival against disinfectants. Pathogenic E. coli PI-7 strain was used as a model bacterium that was exposed to diverse disinfection strategies such as chlorination, UV and solar irradiation. To this end, we used a random transposon mutagenesis library screening approach to generate 14 mutants that exhibited varying levels of virulence traits. In these 14 isolated mutants, we observed that an increase in virulence traits such as biofilm formation, motility, curli production, and internalization capability, increased the inactivation half-lives of mutants compared to wild-type E. coli PI-7. In addition, oxidative stress response and EPS production contributed to lengthening the lag phase duration (defined as the time required for exposure to disinfectant prior to decay). However, traits related to siderophore production did not help with survival against the tested disinfection strategies. Taken together, the findings suggested that selected virulence traits facilitate survival of pathogenic E. coli PI-7, which in turn could account for the selective enrichment of pathogens over the nonpathogenic ones after wastewater treatment. Further, the study also reflected on the effectiveness of UV as a more viable disinfection strategy for inactivation of pathogens.
  • Hole-Type Spacers for More Stable Shale Gas-Produced Water Treatment by Forward Osmosis

    Alqattan, Jawad; Kim, Youngjin; Kerdi, Sarah; Qamar, Adnan; Ghaffour, NorEddine (Membranes, MDPI AG, 2021-01-03) [Article]
    An appropriate spacer design helps in minimizing membrane fouling which remains the major obstacle in forward osmosis (FO) systems. In the present study, the performance of a hole-type spacer (having holes at the filament intersections) was evaluated in a FO system and compared to a standard spacer design (without holes). The hole-type spacer exhibited slightly higher water flux and reverse solute flux (RSF) when Milli-Q water was used as feed solution and varied sodium chloride concentrations as draw solution. During shale gas produced water treatment, a severe flux decline was observed for both spacer designs due to the formation of barium sulfate scaling. SEM imaging revealed that the high shear force induced by the creation of holes led to the formation of scales on the entire membrane surface, causing a slightly higher flux decline than the standard spacer. Simultaneously, the presence of holes aided to mitigate the accumulation of foulants on spacer surface, resulting in no increase in pressure drop. Furthermore, a full cleaning efficiency was achieved by hole-type spacer attributed to the micro-jets effect induced by the holes, which aided to destroy the foulants and then sweep them away from the membrane surface.
  • Combining Nadir, Oblique, and Façade Imagery Enhances Reconstruction of Rock Formations Using Unmanned Aerial Vehicles

    Tu, Yu-Hsuan; Johansen, Kasper; Aragon Solorio, Bruno Jose Luis; Stutsel, Bonny M.; Angel, Yoseline; Camargo, Omar A. López; Al-Mashharawi, Samir K. M.; Jiang, Jiale; Ziliani, Matteo G.; McCabe, Matthew (IEEE Transactions on Geoscience and Remote Sensing, IEEE, 2021) [Article]
    Developments in computer vision, such as structure from motion and multiview stereo reconstruction, have enabled a range of photogrammetric applications using unmanned aerial vehicles (UAV)-based imagery. However, some specific cases still present reconstruction challenges, including survey areas composed of steep, overhanging, or vertical rock formations. Here, the suitability and geometric accuracy of four UAV-based image acquisition and data processing scenarios for topographic surveying applications in complex terrain are assessed and compared. The specific cases include the use of: 1) nadir imagery; 2) nadir and oblique imagery; 3) nadir and façade imagery; and 4) nadir, oblique, and façade imagery to reconstruct a topographically complex natural surface. Results illustrate that including oblique and façade imagery to supplement the more traditional nadir collections significantly improves the geometric accuracy of point cloud data reconstruction by approximately 35% when assessed against terrestrial laser scanning data of near-vertical rock walls. Most points (99.41%) had distance errors of less than 50 cm between the point clouds derived from the nadir imagery and nadir-oblique-façade imagery. Apart from delivering enhanced spatial resolution in façade details, the geometric accuracy improvements achieved from integrating nadir, oblique, and façade imagery provide value for a range of applications, including geotechnical and geohazard investigations. Such gains are particularly relevant for studies assessing rock integrity and stability, and engineering design, planning, and construction, where information on the position of rock cracks, joints, faults, shears, and bedding planes may be required.
  • Zwitterionic Triamine Monomer for the Fabrication of Thin-Film Composite Membranes

    Le, Ngoc Lieu; Phuoc, Duong; Pulido, Bruno A.; Nunes, Suzana Pereira (Industrial & Engineering Chemistry Research, American Chemical Society (ACS), 2020-12-21) [Article]
    A new zwitterionic triamine monomer prepared from tris(2-aminoethyl)amine and 1,3-propane sultone is proposed for the interfacial polymerization with trimesoyl chloride to form thin-film composite membranes for nanofiltration with antifouling properties. The positive effects of the zwitterionic monomer fraction on the surface characteristics of the polyamide layer, fouling resistance, and filtration performance are demonstrated. Increasing the zwitterionic monomers in the selective layer significantly improves the water permeance (two-fold) without affecting the rejection for dyes tested with a molecular weight in the range of 637 and 1673 g/mol. The smoother and more hydrophilic membrane surface of the newly developed membrane provides excellent fouling resistance confirmed by the negligible protein adsorption and permeance drop during the filtration.
  • Enhanced hydraulic cleanability of biofilms developed under a low phosphorus concentration in reverse osmosis membrane systems

    Javier, Luisa; Farhat, Nadia; Vrouwenvelder, Johannes S. (Water Research X, Elsevier BV, 2020-12-15) [Article]
    A critical problem in seawater reverse osmosis (RO) filtration processes is biofilm accumulation, which reduces system performance and increases energy requirements. As a result, membrane systems need to be periodically cleaned by combining chemical and physical protocols. Nutrient limitation in the feed water is a strategy to control biofilm formation, lengthening stable membrane system performance. However, the cleanability of biofilms developed under various feed water nutrient conditions is not well understood. This study analyzes the removal efficiency of biofilms grown in membrane fouling simulators (MFSs) supplied with water varying in phosphorus concentrations (3 and 6 μg P·L-1 and with constant biodegradable carbon concentration) by applying hydraulic cleaning after a defined 140% increase in the feed channel pressure drop, through increasing the cross-flow velocity from 0.18 m s-1 to 0.35 m s-1 for 1 h. The two phosphorus concentrations (3 and 6 μg P·L-1) simulate the RO feed water without and with the addition of a phosphorus-based antiscalant, respectively, and were chosen based on measurements at a full-scale seawater RO desalination plant. Biomass quantification parameters performed after membrane autopsies such as total cell count, adenosine triphosphate, total organic carbon, and extracellular polymeric substances were used along with feed channel pressure drop measurements to evaluate biofilm removal efficiency. The outlet water during hydraulic cleaning (1 h) was collected and characterized as well. Optical coherence tomography images were taken before and after hydraulic cleaning for visualization of biofilm morphology. Biofilms grown at 3 μg P·L-1 had an enhanced hydraulic cleanability compared to biofilms grown at 6 μg P·L-1. The higher detachment for biofilms grown at a lower phosphorus concentration was explained by more soluble polymers in the EPS, resulting in a lower biofilm cohesive and adhesive strength. This study confirms that manipulating the feed water nutrient composition can engineer a biofilm that is easier to remove, shifting research focus towards biofilm engineering and more sustainable cleaning strategies.
  • Genome-Resolved Metagenomics and Antibiotic Resistance Genes Analysis in Reclaimed Water Distribution Systems

    Wang, Changzhi; Hong, Pei-Ying (Water, MDPI AG, 2020-12-10) [Article]
    Water reuse is increasingly pursued to alleviate global water scarcity. However, the wastewater treatment process does not achieve full removal of biological contaminants from wastewater, hence microorganisms and their genetic elements can be disseminated into the reclaimed water distribution systems (RWDS). In this study, reclaimed water samples are investigated via metagenomics to assess their bacterial diversity, metagenome-assembled genomes (MAGs) and antibiotic resistance genes (ARGs) at both point of entry (POE) and point of use (POU) in 3 RWDS. The number of shared bacterial orders identified by metagenome was higher at the POE than POU among the three sites, indicating that specific conditions in RWDS can cause further differentiation in the microbial communities at the end of the distribution system. Two bacterial orders, namely Rhizobiales and Sphingomonadales, had high replication rates in two of the examined RWDS (i.e., site A and B), and were present in higher relative abundance in POU than at POE. In addition, MAG and ARG relative abundance exhibited a strong correlation (R2 = 0.58) in POU, indicating that bacteria present in POU may have a high incidence of ARG. Specifically, resistance genes associated with efflux pump mechanisms (e.g., adeF and qacH) increased in its relative abundance from POU to POE at two of the RWDS (i.e., site A and B). When correlated with the water quality data that suggests a significantly lower dissolved organic carbon (DOC) concentration at site D than the other two RWDS, the metagenomic data suggest that low DOC is needed to maintain the biological stability of reclaimed water along the distribution network.
  • Novel Hole-Pillar Spacer Design for Improved Hydrodynamics and Biofouling Mitigation in Membrane Filtration

    Qamar, Adnan; Kerdi, Sarah; Ali, Syed Muztuza; Shon, Ho Kyong; Vrouwenvelder, Johannes S.; Ghaffour, NorEddine (Research Square, 2020-12-08) [Preprint]
    Abstract Feed spacers are the critical components of any spiral-wound filtration module, dictating the filtration performance. Three spacer designs, namely a non-woven commercial spacer (varying filament cross-section), a symmetric pillar spacer, and a novel hole-pillar spacer (constant filament diameter) were studied using Direct Numerical Simulations (DNS), 3-D printed and subsequently experimentally tested in a lab-scale ultrafiltration set-up with high biofouling potential feed water at various feed pressures. Independent of the applied pressure, the novel hole-pillar spacer showed initially the lowest feed channel pressure drop, the lowest shear stress, and the highest permeate flux compared to the commercial and pillar spacers. Furthermore, less biofilm thickness development on membrane surface was visualized by Optical Coherent Tomography (OCT) imaging for the proposed hole-pillar spacer. At higher feed pressure, a thicker biofilm developed on membrane surface for all spacer designs explaining the stronger decrease in permeate flux at high pressure. The findings systematically demonstrated the role of various spacer designs and applied pressure on the performance of pre-treatment process, while identifying specific shear stress distribution guidelines for engineering a new spacer design in different filtration techniques.
  • Cost of fouling in full-scale reverse osmosis and nanofiltration installations in the Netherlands

    Jafari, M.; Vanoppen, M.; van Agtmaal, J. M.C.; Cornelissen, E. R.; Vrouwenvelder, Johannes S.; Verliefde, A.; van Loosdrecht, M. C.M.; Picioreanu, C. (Desalination, Elsevier BV, 2020-12) [Article]
    The economic impact of fouling in spiral wound membranes is not yet well explored. There has been an established assumption that the cost of fouling in membrane processes is significant, but this hypothesis has not been thoroughly evaluated. We conducted an economic analysis on seven full-scale installations, four nanofiltration (NF) and three reverse osmosis (RO), to estimate the cost of fouling in industrial plants. The cost of fouling was calculated in detail, including costs of increase in feed channel pressure drop, water permeability reduction, early membrane replacement, and extensive cleaning-in-place (CIP). The estimated cost of fouling was expressed as a fraction of operational expenses (OPEX) for each plant and the major cost factors in fouling and CIP costs were identified. The selected NF plants were fed with anoxic ground water, while the feed water to RO plants was either surface water or municipal wastewater effluent. All the NF plants produce drinking water, while the RO plants produce demineralized water for industrial applications. We found that the cost of fouling in the RO plants was around 24% of OPEX, while the fouling related costs in NF cases was only around 11% due to the low biofouling potential of the anoxic ground water. The major factor in the cost of fouling is the early membrane replacement cost, followed by additional energy and with only a minor contribution from the cleaning costs. The down-time cost (caused by the interruption of water production during a CIP event) can be the major CIP cost factor for the plants with frequent cleaning events, while the cost of chemicals dominates in the plants with non-frequent CIP. In case of manual cleaning-in-place, the cost of fouling is increased by around 2% for the RO plants with frequent CIP. The manual execution of CIP cleaning is an attention point to reconsider, as the reviewed plants hold an automated CIP cleaning, providing membrane productivity advantages.
  • Scaling sets the limits of large scale membrane distillation modules for the treatment of high salinity feeds

    Soukane, Sofiane; Elcik, Harun; Alpatova, Alla; Orfi, Jamel; Ali, Emad; AlAnsary, Hany; Ghaffour, NorEddine (Journal of Cleaner Production, Elsevier BV, 2020-12) [Article]
    In this study, the dynamics of scaled-up membrane distillation (MD) modules are tackled for the treatment of highly saline desalination brines. Physical phenomena occurring inside the feed chamber during process scale-up including temperature evolution, species distribution and scaling likeliness were explored using a multicomponent computational fluid dynamics (CFD) model that couples momentum, heat, ions transport and water permeation across the membrane. The model was calibrated with experiments carried out on a lab-scale direct contact MD system fed with concentrated seawater with a salinity of 61 g/L. The complete fall-off of the permeate flux occurred when the salinity reached 170 g/L from 61 g/L, caused by a scaling mostly due to calcium sulfate (gypsum). In order to predict scaling occurrence, an in-house code is embedded in the CFD model to solve Pitzer’s equation at every cell of the domain, enabling the calculation of species activity coefficients, the feed ionic strength, species effective concentration and degree of saturation of the solution with respect to gypsum. Results unveil that during the MD process of brines, the degree of saturation increases considerably in membrane vicinity while the average outlet salinity remains close to that at the inlet due to the relatively high flow rate. Extrapolation to longer modules revealed that an increase in the feed temperature increases the scaling likeliness while flow rates, especially in the high range, did not significantly impact scaling formation. The drop in performance from lab-scale module to a scaled-up size is shown for 1 m long generic modules with and without the use of antiscalants.
  • Fate of polyphenols in forward osmosis

    Pei, Jianfei; Wang, Wenjing; Wang, Yifan; Wang, Haihua; Bucs,Szilard; Vrouwenvelder, Johannes S.; Li, Zhenyu (Journal of Membrane Science, Elsevier BV, 2020-12) [Article]
    The forward osmosis (FO) is an emerging technique for high quality concentration of liquid foods. Polyphenols are natural compounds with important health function in fruit and vegetable juice. In this study, the impacts of membrane property, feed solution (FS) pH value, draw solution (DS) composition and concentration, and membrane fouling on rejections of 9 food polyphenols by FO were investigated. Polyphenol rejection was mainly dominated by size exclusion and electrostatic repulsion. Membrane with higher negative charge and selectivity exhibited higher rejection. The increased pH of FS could enhance negative charge of membrane and thus increased the rejection. Reverse solute diffusion of DS could also enhance rejection via hindering the forward diffusion of polyphenol. The pectin fouling layer acting as the additional filtration barrier could increase the rejection of most selected polyphenols. However, the rejection of polyphenols with smaller molecular size (less than 23.07 Å2) decreased with the pectin fouled membrane and this might be attributed to the effect of cake-enhanced concentration polarization. The present study revealed the fate of polyphenol in FO and provided vital information to further advance the FO application.
  • Flexible isoporous air filters for high-efficiency particle capture

    Sabirova, Ainur; Wang, Shaofei; Falca, Gheorghe; Hong, Pei-Ying; Nunes, Suzana Pereira (Polymer, Elsevier BV, 2020-12) [Article]
    Air pollution with a high concentration level of particulate matter (PM) holds responsibility for an increasing number of fatalities worldwide. Inhalable and harmful airborne PM, generated by anthropogenic and natural sources, can act as carcinogenic agents and can also absorb and transfer with them viruses and bacteria. Stationary and automove filters, masks are part of our routine life. However, traditional fibrous air filters and improved high-efficiency particulate air filters (HEPA) suffer from several inevitable drawbacks, justifying the search for better alternatives. Herein, we present nanofabricated isoporous polymeric membranes with of PM2.5 and PM10 capture efficiency as high as 99.9%. The membranes were transparent and flexible with pore sizes of 0.7, 2 and 5 µm. Those with 2 µm had a density of 4.13 × 106 pores per cm2. Moreover, membranes coated with silver nanoparticles showed excellent biocidal effect against Acinetobacter baylyi bacteria. The membrane can be used in the heating, ventilation and air conditioning systems of buildings and car cabins, and can be incorporated in personal masking.
  • Green solvents for membrane manufacture: Recent trends and perspectives

    Kim, Dooli; Nunes, Suzana Pereira (Current Opinion in Green and Sustainable Chemistry, Elsevier BV, 2020-12) [Article]
    Membrane fabrication highly relies on solution processes. Environmental and health concerns are driving the investigation of alternative green solvents to substitute classical toxic ones. Recent contributions to this topic are reviewed, comparing advantages and drawbacks of manufacturing membranes using water, bio-sourced solvents, non-toxic synthetic organic solvents and ionic liquids as the most explored.
  • Sustainability Evaluation of Hybrid Desalination Systems: Multi Effect Distillation – Adsorption (MED-AD) and Forward Osmosis – Membrane Distillation (FO-MD)

    Son, Hyuk Soo (2020-12) [Dissertation]
    Advisor: Ghaffour, NorEddine
    Committee members: Vrouwenvelder, Johannes S.; Pinnau, Ingo; Orfi, Jamel
    Water is life for all living organisms on earth, and all human beings need water for every socio-economic activity in their daily lives. However, constant challenges are faced in securing quality water resources due to environmental pollution, a growing demand, and climate changes. To overcome imminent worldwide challenges on water resources, desalination of seawater and saline wastewater became inevitable, and significant efforts have been deployed by the desalination research community to advance the technology. However, there is still a gap to take it to a higher sustainability and compatibility compared to conventional water treatment technologies. Among all efforts, the hybridization of two or more processes stands among the promising solutions for sustainable desalination, which synergizes benefits of multiple technologies. To evaluate the sustainability of hybrid desalination technologies, two different systems, namely; (i) multi-effect distillation – adsorption (MED-AD) and (ii) forward osmosis – membrane distillation (FO-MD), are investigated in this study. The method developed for the analysis of primary energy consumption in complex desalination systems is used to evaluate the performance of the MED-AD pilot facility at King Abdullah University of Science and Technology (KAUST). Results of the MED-AD pilot operation showed an improvement in water production with a higher energy efficiency under the same operating conditions (near the ambient temperature with the solar thermal system). For the FO-MD hybrid system, an investigation is carried out on a novel in-house integrated module and a comparative analysis with the conventional module is provided. An isolation barrier carefully placed in the novel design enhanced the hybrid performance by reducing both concentration and temperature polarization. In addition, the FO-MD hybrid process is evaluated for brine reclamation application in a SWRO-MD-FO system. The sustainability of the proposed system and the potential of a flexible sustainable operation are presented with the experimental study with real seawater and brine from the full-scale desalination plant.
  • Nocturnal Surface Urban Heat Island over Greater Cairo: Spatial Morphology, Temporal Trends and Links to Land-Atmosphere Influences

    El Kenawy, Ahmed M.; Hereher, Mohamed; Robaa, Sayed M.; McCabe, Matthew; Lopez-Moreno, Juan I.; Domínguez-Castro, Fernando; Gaber, Islam M.; Al-Awadhi, Talal; Al-Buloshi, Ali; Al Nasiri, Noura; Al-Hatrushi, Salim; Schuwerack, Petra-Manuela; Peña-Angulo, Dhais; Abdelaal, Mohamed M.; Vicente-Serrano, Sergio M. (Remote Sensing, MDPI AG, 2020-11-27) [Article]
    This study assesses the spatial and temporal characteristics of nighttime surface urban heat island (SUHI) effects over Greater Cairo: the largest metropolitan area in Africa. This study employed nighttime land surface temperature (LST) data at 1 km resolution from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua sensor for the period 2003–2019. We presented a new spatial anomaly algorithm, which allowed to define SUHI using the most anomalous hotspot and cold spot of LST for each time step over Greater Cairo between 2003 and 2019. Results demonstrate that although there is a significant increase in the spatial extent of SUHI over the past two decades, a significant decrease in the mean and maximum intensities of SUHI was noted. Moreover, we examined the dependency between SUHI characteristics and related factors that influence energy and heat fluxes between atmosphere and land in urban environments (e.g., surface albedo, vegetation cover, climate variability, and land cover/use changes). Results demonstrate that the decrease in the intensity of SUHI was mainly guided by a stronger warming in daytime and nighttime LST in the neighborhood of urban localities. This warming was accompanied by a decrease in surface albedo and diurnal temperature range (DTR) over these areas. Results of this study can provide guidance to local urban planners and decision-makers to adopt more effective mitigation strategies to diminish the negative impacts of urban warming on natural and human environments.
  • A spatiotemporal indirect evaporative cooler enabled by transiently interceding water mist

    Shahzad, Muhammad Wakil; Lin, Jie; Xu, Ben Bin; Dala, Laurent; Chen, Qian; Burhan, Muhammad; Sultan, Muhammad; Worek, William; Ng, Kim Choon (Energy, Elsevier BV, 2020-11-24) [Article]
    The building sector consumes around half of the global energy produced and air-conditioning processes guzzle over 55% of building sector energy. The conventional refrigerant-based chillers, covering over 90% of the current cooling market, are not only energy-intensive but also have high ozone depletion and global warming potentials. Indirect evaporative coolers were introduced but they were difficult to commercialize due to their practical lower achievable temperature limits. All existing indirect evaporative coolers use hydrophilic interface to provide wet surfaces for evaporative potential. These hydrophilic surfaces not only increase heat transfer resistance but also provide excellent conditions, wet and damp surface, for mold formation. The treatment of mold is almost impossible as the height of the channel is only 3–5 mm and the fungus can be dangerous to health. Therefore, we proposed an innovative indirect evaporative cooling cycle in which there are no hydrophilic surfaces inside the system. The humidification of the working air is carried out before it is introduced into the wet channel. Also, the interface between dry and wet channel is only a thin aluminium foil that boosts heat transfer from supply air to working air in the transverse direction. A generic cell of 1800 mm long and 280 mm wide can produce 182.5 W cooling capacity. The measured coefficient of performance and effectiveness are 45 and 80% respectively for sensible cooling. This basic information of the proposed innovative indirect evaporative cooling system can be used to design a commercial unit as the total capacity is based on number of generic cells.
  • Counterintuitive Wetting Transitions in Doubly Reentrant Cavities as a Function of Surface Make-Up, Hydrostatic Pressure, and Cavity Aspect Ratio

    Arunachalam, Sankara; Ahmad, Zain; Das, Ratul; Mishra, Himanshu (Advanced Materials Interfaces, Wiley, 2020-11-20) [Article]
    Surfaces that entrap air underwater serve numerous practical applications, such as mitigating cavitation erosion and reducing frictional drag. These surfaces typically rely on perfluorinated coatings. However, the non-biodegradability and fragility of the coatings limit practical applications. Thus, coating-free, sustainable, and robust approaches are desirable. Recently, a microtexture comprising doubly reentrant cavities (DRCs) has been demonstrated to entrap air on immersion in wetting liquids. While this is a promising approach, insights into the effects of surface chemistry, hydrostatic pressure, and cavity dimensions on wetting transitions in DRCs remain unavailable. In response, Cassie-to-Wenzel transitions into circular DRCs submerged in water are investigated and compared with those in cylindrical “simple” cavities (SCs). It is found that at low hydrostatic pressures (≈50 Pa), DRCs with hydrophilic (θo ≈ 40°) and hydrophobic (θo ≈ 112°) make-ups fill within 105 and 107 s, respectively, while SCs with hydrophilic make-up fill within <10−2 s. Under elevated hydrostatic pressure (P ≤ 90 kPa), counterintuitively, DRCs with hydrophobic make-up fill dramatically faster than the commensurate SCs. This comprehensive report should provide a rational framework for harnessing microtexturing and surface chemistry toward coating-free liquid repellency.

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