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Recent Submissions

  • The impact of COVID-19 lockdowns on surface urban heat island changes and air-quality improvements across 21 major cities in the Middle East.

    El Kenawy, Ahmed M; Lopez-Moreno, Juan I; McCabe, Matthew; Domínguez-Castro, Fernando; Peña-Angulo, Dhais; Gaber, Islam M; Alqasemi, Abduldaem S; Al Kindi, Khalifa M; Al-Awadhi, Talal; Hereher, Mohammed E; Robaa, Sayed M; Al Nasiri, Noura; Vicente-Serrano, Sergio M (Environmental pollution (Barking, Essex : 1987), Elsevier BV, 2021-07-20) [Article]
    This study investigates changes in air quality conditions during the restricted COVID-19 lockdown period in 2020 across 21 metropolitan areas in the Middle East and how these relate to surface urban heat island (SUHI) characteristics. Based on satellite observations of atmospheric gases from Sentinel-5, results indicate significant reductions in the levels of atmospheric pollutants, particularly nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). Air quality improved significantly during the middle phases of the lockdown (April and May), especially in small metropolitan cities like Amman, Beirut, and Jeddah, while it was less significant in “mega” cities like Cairo, Tehran, and Istanbul. For example, the concentrations of NO2 in Amman, Beirut, and Jeddah decreased by −56.6%, −43.4%, and −32.3%, respectively, during April 2020, compared to April 2019. Rather, there was a small decrease in NO2 levels in megacities like Tehran (−0.9%) and Cairo (−3.1%). Notably, during the lockdown period, there was a decrease in the mean intensity of nighttime SUHI, while the mean intensity of daytime SUHI experienced either an increase or a slight decrease across these locations. Together with the Gulf metropolitans (e.g. Kuwait, Dubai, and Muscat), the megacities (e.g. Tehran, Ankara, and Istanbul) exhibited anomalous increases in the intensity of daytime SUHI, which may exceed 2 °C. Statistical relationships were established to explore the association between changes in the mean intensity and the hotspot area in each metropolitan location during the lockdown. The findings indicate that the mean intensity of SUHI and the spatial extension of hotspot areas within each metropolitan had a statistically significant negative relationship, with Pearson's r values generally exceeding - 0.55, especially for daytime SUHI. This negative dependency was evident for both daytime and nighttime SUHI during all months of the lockdown. Our findings demonstrate that the decrease in primary pollutant levels during the lockdown contributed to the decrease in the intensity of nighttime SUHIs in the Middle East, especially in April and May. Changes in the characteristics of SUHIs during the lockdown period should be interpreted in the context of long-term climate change, rather than just the consequence of restrictive measures. This is simply because short-term air quality improvements were insufficient to generate meaningful changes in the region's urban climate.
  • Defining sulfonation limits of poly(ether-ether-ketone) for energy-efficient dehumidification

    Akhtar, Faheem; Abdulhamid, Mahmoud; Vovusha, Hakkim; Ng, Kim Choon; Schwingenschlögl, Udo; Szekely, Gyorgy (Journal of Materials Chemistry A, Royal Society of Chemistry (RSC), 2021-07-06) [Article]
    Dehumidification is a vital process in the cooling industry and has emerged as a promising tool for alleviating the effects of energy-intensive activities. Advanced engineering materials, which can be employed in dehumidification processes, have attracted considerable attention. However, the majority of commercial adsorbents suffer from low sorption performance in arid climates. In this work, sulfonated poly(ether-ether-ketones) (SPEEKs) were designed as desiccants for dehumidification processes. The in silico and experimental investigations at a molecular level enabled the development of desiccants exhibiting outstanding water uptake capacity of more than 300%, fast sorption uptake, and high transport rate. The sorption capacity of the prepared materials outperformed those of the previously reported desiccants. Membrane performance analyses demonstrated remarkably high water vapor permeability and selectivity; therefore, the desiccants developed herein showed potential for application in water vapor control and dehumidification processes in enclosed or confined spaces. Contrary to common assumptions, the correlation between the sulfonation degree and dehumidification performance showed a plateau after maximum curvature. The results of this study open new directions for tailoring energy-efficient materials for dehumidification processes.
  • Stimuli-Responsive Lysozyme Nanocapsule Engineered Microfiltration Membranes with a Dual-Function of Anti-Adhesion and Antibacteria for Biofouling Mitigation

    Li, Sihang; Zhao, Shuzhen; Pei, Jianfei; Wang, Haihua; Meng, Huanna; Vrouwenvelder, Johannes S.; Li, Zhenyu (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2021-07-05) [Article]
    Biofouling remains as a persistent problem impeding the applications of membranes for water and wastewater treatment. Green anti-biofouling of membranes made of natural and environmentally friendly materials and methods is a promising strategy to tackle this problem. Herein, we have developed a functionalized PVDF membrane with stimuli-responsive lysozyme nanocapsules (NCP). These nanocapsules can responsively release lysozyme according to environmental stimuli (pH and redox) induced by bacteria. Results showed that (i) the surface of the functionalized membrane with NCP had enhanced hydrophilicity, reduced roughness, and negative charge, (ii) a remarkable reduction of adsorption of proteins, polysaccharides, and bacteria was achieved by the functionalized membrane, and (iii) the colony forming unit (CFU) of bacteria on a membrane surface was reduced more than 80% within 24 h of contact. In addition, the NCP membrane showed excellent anti-biofouling activity regarding the bacterial viability being 12.5 and 8.3% on the membrane after filtration with 108 CFU mL–1Escherichia coli and Staphylococcus aureus solution as feed, respectively. The coating layer and assembled nanocapsules endowed the membrane with improved lysozyme stability, anti-adhesion performance, and antibacterial activity. Stimuli-responsive lysozyme nanocapsule engineered microfiltration membranes show great potential for anti-biofouling in future practical application.
  • Produced Water Pretreatment Prior to Filtration with Forward Osmosis and Membrane Distillation Integrated System

    Alqulayti, Abdullah (2021-07) [Thesis]
    Advisor: Ghaffour, NorEddine
    Committee members: Saikaly, Pascal; Fortunato, Luca; Saqib Nawaz, Muhammad
    The simultaneous treatment of different produced water streams with the forward osmosis membrane distillation hybrid system (FO-MD) has been suggested recently. This work investigates the need for pretreatment of produced water prior to filtration with FO-MD in order to reduce the level of fouling and scaling in the system. The desalter effluent (DE) stream was selected as FO feed solution, and the water oil separator (WO) stream was used as FO draw solution/MD feed solution, and a significant flux decline was observed in FO and MD within the first 5 hours of operations. SEM and EDX analysis indicated that the formation of scale layer on both membranes was the main reason for the sharp flux decline. Silica was the major contributor to the scaling of the support layer of the FO membrane. While the scaling layer on MD membrane consisted mainly of CaSO4 crystals with some deposition of Silica. Therefore, electrocoagulation (EC) was selected for the pretreatment of produced water to target the removal of Ca, SiO2 and SO4 ions in order to reduce the likelihood of inorganic fouling in FO-MD. The different parameters of EC, namely, the current density, electrolysis time, and initial pH were tested at a wide range of values of 7-70 mA/cm2 , 10-60 minutes, 5-9, respectively. calcium and sulfate ions were not effectively removed at the relatively high applied current density of 70 mA/cm2 , while high removal of silica was achieved even at low applied current densities. The optimum conditions of EC for silica removal were found to be 7 mA/cm2 for the current density and 10 minutes for the electrolysis time which resulted in a 97% removal of silica. it was found that due to pretreatment, the average FO and MD fluxes increased by 49% (9.93 LMH) and 39% (8.55 LMH), respectively. Therefore, even though EC did not show promising results in terms of the removal of calcium and sulfate, efficient silica removal was achieved with minimum energy requirements which suggests that it could have a potential to be integrated with the FO-MD hybrid system for the treatment and reclamation of produced water.
  • Evaluation of Different Forward Osmosis Membrane Cleaning Strategies for Produced Water Streams Treatment

    Alamoudi, Talal (2021-07) [Thesis]
    Advisor: Ghaffour, NorEddine
    Committee members: Pinnau, Ingo; Vrouwenvelder, Johannes S.; Saqib Nawaz, Muhammad
    Forward osmosis (FO) as a novel membrane separation technology has recently been investigated in various water treatment applications. The natural mass transfer process between two solutions driven by the osmotic pressure difference leads to many operational advantages in the FO process, such as low energy consumption and minimal fouling problems. It makes FO a feasible technology for the treatment of produced water (PW). Although previously, the treatment of PW using FO has been investigated, osmotic backwashing (OB) is not systematically examined for water flux recovery of the PW fouled FO membranes. Moreover, the cleaning of FO membranes used for the simultaneous treatment of different PW streams was never previously attempted. In this study, OB was thoroughly investigated for the cleaning of PW-fouled FO membranes. Also, FO membrane chemical cleaning using SDS and NaOH solutions was examined too. To investigate OB, the cleaning efficiency of a 60 min OB cleaning protocol was examined under different FO operating modes in (5 x 20 h) experiments using synthetic desalter effluent as FO feed solution (FS) and 1.2 M NaCl solution or water-oil separator outlet (WO) as draw solutions (DS). The AL-FS (active layer facing FS) mode outcompeted the AL-DS (active layer facing DS) mode, achieving a flux of 12.9 LMH and 80.1% water reclamation when using WO as a DS. Therefore, this FO configuration 5 was selected when evaluating the cleaning protocols. Moreover, after evaluating different OB methods, the 30 min OB protocol achieved the highest system efficiency rate of 95% and was studied for the treatment of real PW streams. The SDS and NaOH chemical cleaning methods achieved flux recovery rates of 99% and 98% by the end of the third treatment cycle, respectively, outperforming the 89% flux recovery rate of the optimized OB protocol. Although the investigated cleaning methods were able to restore the system performance, a substantial increase in RSF was observed due to mainly irreversible colloidal fouling. This study demonstrates the feasibility of OB and chemical cleaning in restoring FO system performance for the simultaneous treatment of PW streams
  • Coupling anaerobic fluidized membrane bioreactors with microbial electrolysis cells towards improved wastewater reuse and energy recovery

    El Kik, Olga; Issa, Lea; Katuri, Krishna; Saikaly, Pascal; Alameddine, Ibraim; El-Fadel, Mutasem; Saikaly, Pascal (Journal of Environmental Chemical Engineering, Elsevier BV, 2021-07) [Article]
    Anaerobic Membrane Bioreactors (AnMBRs) combine the advantages of anaerobic processes and MBR technology to improve effluent quality and energy recovery. However, these systems are associated with operational challenges such as membrane fouling and loss of dissolved methane that increases operation and energy expenses. In this study, a new configuration was developed combining AnMBRs with Microbial Electrolysis Cells (MECs). The effectiveness of the coupled AnFMBR-MEC system was tested by monitoring several indicators during the treatment of synthetic wastewater. The new configuration exhibited a 25-day shorter startup period, a 56% enhanced average methane yield, and a reduced membrane fouling with a maximum transmembrane pressure value nearly 6.5 folds lower than that exhibited by the AnFMBR alone. AnFMBR-MEC had an average CE of 40% and both reactors achieved around 90% COD removal. Similar bacterial communities existed in both reactors but with different relative abundance and localization. In the AnFMBR-MEC, the Direct Interspecies Electron Transfer was the likely dominant route for acetate consumption due to the abundance of Geobacter and Methanosarcina on the granular activated carbon and in suspension. The new system offers a promising technology with less fouling and improved resource recovery from wastewater due to the presence of different environmental niches (GAC, anode, cathode) for microbial colonization and growth, which resulted in the reduction of biomass in suspension and the proliferation of electroactive bacteria and methanogens as biofilms.
  • Impact of Different Cleaning Methods on Biofilm Removal in Membrane Distillation

    Amin, Najat A. (2021-07) [Thesis]
    Advisor: Ghaffour, NorEddine
    Committee members: Vrouwenvelder, Johannes S.; Alpatova, Alla
    Membrane distillation (MD) is an emerging thermal separation technology which proved its efficiency in desalination of highly saline waters, including seawater, brines and impaired process waters. In a long-term prospective, MD can reinforce sustainability of the clean water production and mitigate the water-energy stress caused by lacking suitable freshwater recourses. However, just like in any other membrane separation process, MD membrane is susceptible to biofouling which presents a significant challenge by substantially reducing its performance and deteriorating permeate quality. This study evaluated different cleaning methods aimed at controlling biofilm development on a surface of hydrophobic MD membrane in a direct contact MD (DCMD) process fed by the Red Sea water. This was achieved by applying physical (hydraulic) cleaning and chemical cleanings with a range of chemicals utilized in membrane separation processes including citric acid (mineral acid), ethylenediaminetetraacetic acid (EDTA, metal-chelating agent) and sodium hypochlorite (NaOCl, oxidant). Flux recovery and changes in biofilm morphology, including its thickness and structure as well as microbial and extracellular polymeric substances (EPS) contents before and after cleanings have been analyzed to elucidate cleaning mechanisms and suggest effective strategies of biofilm removal. The results showed that 0.3% EDTA exhibited the best cleaning performance resulting in the highest permeate flux recovery (93%), followed by 0.3% NaOCl (89%), 3% citric acid (76%), and hydraulic (66%) cleanings. Application of EDTA and NaOCl has also resulted in the lowest number of bacterial cells and substantial reduction of the peak intensities caused by protein-like compounds and tyrosine-containing proteins present on the membrane surface after its treamtent. The observed trends are in a good correlation with the optical coherence tomography (OCT) observations which revealed substation changes in biofilm morphology leading to a significant reduction of biofilm thickness which followed the order of hydraulic cleaning < citric acid cleaning < NaOCl cleaning < EDTA cleaning. This study suggests that selection of an appropriate cleaning type and formulation is critical for achieving sustainable MD plant operations, both technically and economically.
  • Bottled Drinking Water: Assessment of Physical-Chemical and Microbiological Parameters and Biological Stability of 19 Different Brands Available in Saudi Arabia

    Nadreen, Yasmeen (2021-07) [Thesis]
    Advisor: Vrouwenvelder, Johannes S.
    Committee members: Gonzalez-Gil, Graciela; Saikaly, Pascal
    Bottled drinking water is a common form of water consumption that has grown in popularity and dependency. With countless types and brands available, there are factors to consider regarding the variations in mineral content and microbiological quality, and environmental consequences associated with importing natural bottled waters. Saudi Arabia is the largest desalinated water producer, and although there are scarce natural water resources, consuming locally produced water can alleviate environmental pressures, so long as local bottled water is of good quality and provides the basic function of drinking water. The objective of this study is to scrutinize the variations in bottled waters available in the Saudi market and compare local and imported waters regarding water quality and compliance with health regulations. Surveying local bottled waters revealed that over 60% were imported, adding to the environmental significance. Results from inductively coupled plasma-atomic emission spectroscopy, ion chromatography, and pH meters indicate most bottled waters were compliant with health standards. Flow Cytometry (FCM) was used to determine microbial cell densities. Purified waters, on average, contained significantly lower concentrations than other water types, while mineral waters contained the most cells per milliliter. Microbiological stability was examined through incubating samples at 30°C to promote microbial growth, and results were analyzed using an online FCM system. Purified waters had the least amount of growth and to a lesser degree than mineral and sparkling, which varied in microbial growth responses. DNA extractions and microbial community analyses were performed on select mineral waters before and after incubation. Results showed microbial genera found were similar between samples from the same country and some were unique. All samples exhibited some change in microbial community composition after incubation, signifying that certain communities thrived more than others. Proteobacteria was the most common abundant phylum among samples. Although analysis was restricted to the genera level, there were no health concern associated with types of bacteria discovered. In conclusion, local purified waters had greater microbiological quality and stability than imported waters, and mineral compositions were within the healthy range. Reducing reliance on foreign natural waters may help alleviate environmental consequences and improve local economy
  • A Multi-platform Comparison of Phenology for Semi-automated Classification of Crops

    Kanee, Sarah (2021-07) [Thesis]
    Advisor: McCabe, Matthew
    Committee members: Johansen, Kasper; Blilou, Ikram
    Remote sensing has enabled unprecedented earth observation from space and has proven to be an invaluable tool for agricultural applications and crop management practices. Here we detect seasonal metrics indicating the start of the season (SOS), the end of the season (EOS) and maximum greenness (MAX) based on vegetation spectral signatures and the normalized difference vegetation index (NDVI) for a time series of Landsat-8, Sentinel-2 and PlanetScope imagery of potato, wheat, watermelon, olive and peach/apricot fields. Seasonal metrics were extracted from NDVI curves and the effect of different spatial and temporal resolutions was assessed. It was found that Landsat-8 overestimated SOS and EOS and underestimated MAX due to its low temporal resolution, while Sentinel-2 offered the most reliable results overall and was used to classify the fields in Aljawf. Planet data reported the most precise SOS and EOS, but proved challenging for the framework because it is not a radiometrically normalized product, contained clouds in its imagery, and was difficult to process because of its large volume. The results demonstrate that a balance between the spatial and temporal resolution of a satellite is important for crop monitoring and classification and that ultimately, monitoring vegetation dynamics via remote sensing enables efficient and data-driven management of agricultural system
  • Monitoring crop development and health using UAV-based hyperspectral imagery and machine learning

    Angel, Yoseline (2021-07) [Dissertation]
    Advisor: McCabe, Matthew
    Committee members: Hong, Pei-Ying; Tester, Mark A.; Zarco-Tejada, Pablo
    Agriculture faces many challenges related to the increasing food demands of a growing global population and the sustainable use of resources in a changing environment. To address them, we need reliable information sources, like exploiting hyperspectral satellite, airborne, and ground-based remote sensing data to observe phenological traits through a crops growth cycle and gather information to precisely diagnose when, why, and where a crop is suffering negative impacts. By combining hyperspectral capabilities with unmanned aerial vehicles (UAVs), there is an increased capacity for providing time-critical monitoring and new insights into patterns of crop development. However, considerable effort is required to effectively utilize UAV-integrated hyperspectral systems in crop-modeling and crop-breeding tasks. Here, a UAV-based hyperspectral solution for mapping crop physiological parameters was explored within a machine learning framework. To do this, a range of complementary measurements were collected from a field-based phenotyping experiment, based on a diversity panel of wild tomato (Solanum pimpinellifolium) that were grown under fresh and saline conditions. From the UAV data, positionally accurate reflectance retrievals were produced using a computationally robust automated georectification and mosaicking methodology. The resulting multitemporal UAV data were then employed to retrieve leaf-chlorophyll (Chl) dynamics via a machine learning framework. Several approaches were evaluated to identify the best-performing regression supervised methods. An investigation of two learning strategies (i.e., sequential and retraining) and the value of using spectral bands and vegetation indices (VIs) as prediction features was also performed. Finally, the utility of UAVbased hyperspectral phenotyping was demonstrated by detecting the effects of salt-stress on the different tomato accessions by estimating the salt-induced senescence index from the retrieved Chl dynamics, facilitating the identification of salt-tolerant candidates for future investigations. This research illustrates the potential of UAV-based hyperspectral imaging for plant phenotyping and precision agriculture. In particular, a) developing systematic imaging calibration and pre-processing workflows; b) exploring machine learning-driven tools for retrieving plant phenological dynamics; c) establishing a plant stress detection approach from hyperspectral-derived metrics; and d) providing new insights into using computer vision, big-data analytics, and modeling strategies to deal effectively with the complexity of the UAV-based hyperspectral data in mapping plant physiological indicators.
  • Textile dye wastewater treatment by direct contact membrane distillation: Membrane performance and detailed fouling analysis

    Fortunato, Luca; Elcik, Harun; Blankert, Bastiaan; Ghaffour, NorEddine; Vrouwenvelder, Johannes S. (Journal of Membrane Science, Elsevier BV, 2021-06-25) [Article]
    The treatment of textile dye solution is considered one of the most challenging wastewater treatments, representing a major concern for the ecosystem. This study investigates the efficiency of direct contact membrane distillation (DCMD) for the treatment of synthetic textile solution in lab test membrane cells. The effect of the feed temperature and feed flow rate on the MD fouling were investigated at feed water temperatures of 40 °C, 60 °C, 80 °C and feed flow rates of 15 L/h, 30 L/h and 45 L/h. Results show that (i) negligible fouling was observed at a feed temperature of 40 °C, (ii) the increase in temperature impacted the process performance, leading to severe flux decrease (∼70%) and to the formation of a thick fouling layer (240 μm) at a feed temperature of 80 °C, (iii) fouling thickness was reduced with increasing feed flow velocity, (iv) the fouling increased toward the inlet side of the membrane cell due to the variation of the driving force along the module. In-situ non-invasive fouling monitoring allowed evaluating the fouling spatial distribution on the membrane, and linking the MD process performance to the fouling accumulation, indicating a linear correlation between the flux decrease and the fouling deposition.
  • Dynamic feed spacer for fouling minimization in forward osmosis process

    Ali, Syed Muztuza; Kim,Youngjin; Qamar, Adnan; Naidu, Gayathri; Phuntsho, Sherub; Ghaffour, NorEddine; Vrouwenvelder, Johannes S.; Shon, Ho Kyong (Desalination, Elsevier BV, 2021-06-25) [Article]
    In this study, a dynamic feed spacer is used to minimize the fouling problem of forward osmosis (FO) membrane process. The conceptual design of the spacer consists of a series of microturbines assembled in ladder type filament cells and termed as turbospacer. It exploits the kinetic energy of the flowing feed solution to rotate the turbines and creates high flow turbulence in the feed channel to prevent the accumulation of foulants and related performance decline. This proof of concept study employed a 3D printed prototype of the proposed spacer in a lab-scale FO experimental setup to compare their performances with a symmetric non-woven spacer of the same thickness under the same operating condition as a reference. Primary effluent from municipal wastewater treatment plant was used as feed solution for a short term (6 days) fouling experiment in this study. Outcomes of the FO fouling experiment revealed that the turbospacer resulted in (i) a factor 2 lower spacer channel pressure drop built-up, and (ii) a 15% reduction in flux decline compared to the reference symmetric spacer. Almost 2.5 times lower foulant resistance was obtained by using the turbospacer at the end of the fouling experiment. In addition, the analysis of the foulant layer growth over a particular position of the membrane surface captured by an optical coherence tomography (OCT) device at different stages of the experiment exhibited that the turbospacer produced a thinner foulant layer. In summary, the turbospacer demonstrated better fouling prevention and control in the FO process.
  • Evaluation of DNA extraction yield from a chlorinated drinking water distribution system

    Putri, Ratna E.; Kim, Lan Hee; Farhat, Nadia; Felemban, Mashael; Saikaly, Pascal; Vrouwenvelder, Johannes S. (PLOS ONE, Public Library of Science (PLoS), 2021-06-24) [Article]
    Desalination technology based on Reverse Osmosis (RO) membrane filtration has been resorted to provide high-quality drinking water. RO produced drinking water is characterized by a low bacterial cell concentration. Monitoring microbial quality and ensuring membrane-treated water safety has taken advantage of the rapid development of DNA-based techniques. However, the DNA extraction process from RO-based drinking water samples needs to be evaluated regarding the biomass amount (filtration volume) and residual disinfectant such as chlorine, as it can affect the DNA yield. We assessed the DNA recovery applied in drinking water microbiome studies as a function of (i) different filtration volumes, (ii) presence and absence of residual chlorine, and (iii) the addition of a known Escherichia coli concentration into the (sterile and non-sterile, chlorinated and dechlorinated) tap water prior filtration, and directly onto the (0.2 μm pore size, 47 mm diameter) mixed ester cellulose membrane filters without and after tap water filtration. Our findings demonstrated that the co-occurrence of residual chlorine and low biomass/cell density water samples (RO-treated water with a total cell concentration ranging between 2.47 × 102–1.5 × 103 cells/mL) failed to provide sufficient DNA quantity (below the threshold concentration required for sequencing-based procedures) irrespective of filtration volumes used (4, 20, 40, 60 L) and even after performing dechlorination. After exposure to tap water containing residual chlorine (0.2 mg/L), we observed a significant reduction of E. coli cell concentration and the degradation of its DNA (DNA yield was below detection limit) at a lower disinfectant level compared to what was previously reported, indicating that free-living bacteria and their DNA present in the drinking water are subject to the same conditions. The membrane spiking experiment confirmed no significant impact from any potential inhibitors (e.g. organic/inorganic components) present in the drinking water matrix on DNA extraction yield. We found that very low DNA content is likely to be the norm in chlorinated drinking water that gives hindsight to its limitation in providing robust results for any downstream molecular analyses for microbiome surveys. We advise that measurement of DNA yield is a necessary first step in chlorinated drinking water distribution systems (DWDSs) before conducting any downstream omics analyses such as amplicon sequencing to avoid inaccurate interpretations of results based on very low DNA content. This study expands a substantial source of bias in using DNA-based methods for low biomass samples typical in chlorinated DWDSs. Suggestions are provided for DNA-based research in drinking water with residual disinfectant.
  • Smart Sand by Surface Engineering: Toward Controllable Oil/Water Separation

    Chang, Jian; Ong, Chi Siang; Shi, Yusuf; Yuan, Jiayin; Ahmed, Zeyad; Wang, Peng (Industrial & Engineering Chemistry Research, American Chemical Society (ACS), 2021-06-23) [Article]
    Sand, an abundant resource from the nature, is a promising candidate for oil/water separation. Herein, raw sand was designed with switchable surface wettability to enable recyclability and versatility in practical oil/water separation. The “smart” sand was fabricated by grafting pH-responsive poly(4-vinylpyridine) (P4VP) and oleophilic/hydrophobic octadecyltrimethoxysilane (OTS) onto its surface. The decorated sand can be used as the oil sorbent for controllable oil sorption and desorption in response to different pHs, as well as a filter to selectively separate either oil or water on demand. This novel design offers an intelligent, low-cost, large-scale, and highly efficient route to potentially settle the issues of industrial oily wastewater and oil spill.
  • Potential Pitfalls in Membrane Fouling Evaluation: Merits of Data Representation as Resistance Instead of Flux Decline in Membrane Filtration

    Blankert, Bastiaan; Van der Bruggen, Bart; Childress, Amy E.; Ghaffour, NorEddine; Vrouwenvelder, Johannes S. (Membranes, MDPI AG, 2021-06-22) [Article]
    The manner in which membrane-fouling experiments are conducted and how fouling performance data are represented have a strong impact on both how the data are interpreted and on the conclusions that may be drawn. We provide a couple of examples to prove that it is possible to obtain misleading conclusions from commonly used representations of fouling data. Although the illustrative example revolves around dead-end ultrafiltration, the underlying principles are applicable to a wider range of membrane processes. When choosing the experimental conditions and how to represent fouling data, there are three main factors that should be considered: (I) the foulant mass is principally related to the filtered volume; (II) the filtration flux can exacerbate fouling effects (e.g., concentration polarization and cake compression); and (III) the practice of normalization, as in dividing by an initial value, disregards the difference in driving force and divides the fouling effect by different numbers. Thus, a bias may occur that favors the experimental condition with the lower filtration flux and the less-permeable membrane. It is recommended to: (I) avoid relative fouling performance indicators, such as relative flux decline (J/J0); (II) use resistance vs. specific volume; and (III) use flux-controlled experiments for fouling performance evaluation.
  • Integrated solar-driven PV cooling and seawater desalination with zero liquid discharge

    Wang, Wenbin; Aleid, Sara; Shi, Yifeng; Zhang, Chenlin; Li, Renyuan; Wu, Mengchun; Zhuo, Sifei; Wang, Peng (Joule, Elsevier BV, 2021-06-16) [Article]
    Utilizing the ‘‘waste heat’’ of solar cells for desalination enables the simultaneous production of freshwater and electricity and represents low barrier-of-entry electricity and freshwater supplies to off-grid communities for point of consumption. Herein, guided by theoretical modeling, this project demonstrated that a higher freshwater production rate and a lower solar cell temperature could be achieved simultaneously. With a five-stage photovoltaics-membrane distillation-evaporative crystallizer (PME), we experimentally demonstrated a high and stable freshwater production rate of 2.45 kg m2 h1 and a reduced solar cell temperature of 47 C under 1 sun irradiation, as compared to 62 C of the same solar cell working alone. The reduced solar cell temperature led to an 8% increase in its electricity production. Moreover, the concentrated brine produced in the process was fully evaporated by the underlying evaporative crystallizer, achieving zero liquid discharge. We expect that our work will have important implications for the understanding and advancement of solar distillation.
  • Hybrid water vapor sorbent design with pollution shielding properties: extracting clean water from polluted bulk water sources

    Li, Renyuan; Wu, Mengchun; Shi, Yusuf; Aleid, Sara; Wang, Wenbin; Zhang, Chenlin; Wang, Peng (JOURNAL OF MATERIALS CHEMISTRY A, Royal Society of Chemistry (RSC), 2021-06-11) [Article]
    The shortage and contamination of local water resources have long been a challenge especially for off-grid communities without centralized water supply. The emerging solar photothermal distillation lacks the capability of handling polluted source water with a wide range of common environmental pollutants. Based on water vapor harvesting, this work reports a Simple Water Extraction Apparatus with Pollutant Shielding (SWEAPS) design which is able to efficiently produce clean water from various polluted liquid water sources and the atmosphere. SWEAPS is fabricated by encapsulating a water vapor sorbent by an omniphobic fabric. The omniphobicity of the encapsulation fabric endows SWEAPS with self-floating capability and the ability to screen out the contaminants in the source water. The self-floating properties of SWEAPS allow it to harvest clean water vapor right above the source-water–air interface where the relative humidity is close to 100%, leading to its much higher water harvesting capacity than that of the same material harvesting water vapor from the ambient atmosphere. Due to the chemical and physical stability, anti-bacterial, pollution and corrosion shielding effects of SWEAPS, it is demonstrated to produce clean water meeting the WHO drinking water standard from various polluted water resources, such as seawater, contaminated water, and amazingly untreated real domestic wastewater. SWEAPS has the potential to produce clean water for point of consumption at a decentralized scale and thus to improve the quality of life for those who need water most.
  • CubeSats deliver new insights into agricultural water use at daily and 3 m resolutions

    Aragon Solorio, Bruno Jose Luis; Ziliani, Matteo G.; Houborg, Rasmus; Franz, Trenton E.; McCabe, Matthew (Scientific Reports, Springer Science and Business Media LLC, 2021-06-09) [Article]
    Earth observation has traditionally required a compromise in data collection. That is, one could sense the Earth with high spatial resolution occasionally; or with lower spatial fidelity regularly. For many applications, both frequency and detail are required. Precision agriculture is one such example, with sub-10 m spatial, and daily or sub-daily retrieval representing a key goal. Towards this objective, we produced the first cloud-free 3 m daily evaporation product ever retrieved from space, leveraging recently launched nano-satellite constellations to showcase this emerging potential. Focusing on three agricultural fields located in Nebraska, USA, high-resolution crop water use estimates are delivered via CubeSat-based evaporation modeling. Results indicate good model agreement (r2 of 0.86–0.89; mean absolute error between 0.06 and 0.08 mm/h) when evaluated against corrected flux tower data. CubeSat technologies are revolutionizing Earth observation, delivering novel insights and new agricultural informatics that will enhance food and water security efforts, and enable rapid and informed in-field decision making.
  • Natural deep eutectic solvents as biofilm structural breakers

    Nava Ocampo, Maria F.; Al Fuhaid, Lamya; Verpoorte, Robert; Choi, Young Hae; van Loosdrecht, Mark C.M.; Vrouwenvelder, Johannes S.; Witkamp, Geert Jan; Farinha, Andreia S.F.; Bucs,Szilard (Water Research, Elsevier BV, 2021-06) [Article]
    Natural Deep Eutectic Solvents (NADES) are composed of supramolecular interactions of two or more natural compounds, such as organic acids, sugars, and amino acids, and they are being used as a new media alternative to conventional solvents. In this study, a new application of NADES is presented as a possible technology for biofilm structural breaker in complex systems since the current solvents used for biofilm cleaning and extraction of biofilm components use hazardous solutions. The NADES (betaine:urea:water and Lactic acid:glucose:water) were analyzed before and after the biofilm treatment by attenuated total reflection Fourier-transform infrared spectroscopy and fluorescence excitation-emission matrix spectroscopy. Our results indicate that the green solvents could solubilize up to ≈70 percent of the main components of the biofilms extracellular matrix. The solubilization of the biomolecules weakened the biofilm structure, which could enhance the biofilm solubilization and removal. The NADES have the potential to be an environment-friendly, green solvent to extract valuable compounds and break the main structure from the biofilm, leading to a greener method for extracellular polymeric substance (EPS) extraction and biofilm treatment in various water treatment systems.
  • Competition of two highly specialized and efficient acetoclastic electroactive bacteria for acetate in biofilm anode of microbial electrolysis cell

    Sapireddy, Veerraghavulu; Katuri, Krishna; Ali, Muhammad; Saikaly, Pascal (npj Biofilms and Microbiomes, Springer Science and Business Media LLC, 2021-05-31) [Article]
    Maintaining functional stability of microbial electrolysis cell (MEC) treating wastewater depends on maintaining functional redundancy of efficient electroactive bacteria (EAB) on the anode biofilm. Therefore, investigating whether efficient EAB competing for the same resources (electron donor and acceptor) co-exist at the anode biofilm is key for the successful application of MEC for wastewater treatment. Here, we compare the electrochemical and kinetic properties of two efficient acetoclastic EAB, Geobacter sulfurreducens (GS) and Desulfuromonas acetexigens (DA), grown as monoculture in MECs fed with acetate. Additionally, we monitor the evolution of DA and GS in co-culture MECs fed with acetate or domestic wastewater using fluorescent in situ hybridization. The apparent Monod kinetic parameters reveal that DA possesses higher jmax (10.7 ± 0.4 A/m2) and lower KS, app (2 ± 0.15 mM) compared to GS biofilms (jmax: 9.6 ± 0.2 A/m2 and KS, app: 2.9 ± 0.2 mM). Further, more donor electrons are diverted to the anode for respiration in DA compared to GS. In acetate-fed co-culture MECs, DA (98% abundance) outcompete GS for anode-dependent growth. In contrast, both EAB co-exist (DA: 55 ± 2%; GS: 24 ± 1.1%) in wastewater-fed co-culture MECs despite the advantage of DA over GS based on kinetic parameters alone. The co-existence of efficient acetoclastic EAB with high current density in MECs fed with wastewater is significant in the context of functional redundancy to maintain stable performance. Our findings also provide insight to future studies on bioaugmentation of wastewater-fed MECs with efficient EAB to enhance performance.

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