• A 3D Photothermal Structure toward Improved Energy Efficiency in Solar Steam Generation

      Shi, Yusuf; Li, Renyuan; Jin, Yong; Zhuo, Sifei; Shi, Le; Chang, Jian; Hong, Seunghyun; Ng, Kim Choon; Wang, Peng (Joule, Elsevier BV, 2018-04-18) [Article]
      Summary The energy efficiency in solar steam generation by 2D photothermal materials has approached its limit. In this work, we fabricated 3D cylindrical cup-shaped structures of mixed metal oxide as solar evaporator, and the 3D structure led to a high energy efficiency close to 100% under one-sun illumination due to the capability of the cup wall to recover the diffuse reflectance and thermal radiation heat loss from the 2D cup bottom. Additional heat was gained from the ambient air when the 3D structure was exposed under one-sun illumination, leading to an extremely high steam generation rate of 2.04 kg m−2 h−1. The 3D structure has a high thermal stability and shows great promise in practical applications including domestic wastewater volume reduction and seawater desalination. The results of this work inspire further research efforts to use 3D photothermal structures to break through the energy efficiency limit of 2D photothermal materials.
    • Accuracy comparison of remotely sensed evapotranspiration products and their associated water stress footprints under different land cover types in Korean peninsula

      Liaqat, Umar Waqas; Choi, Minha (Journal of Cleaner Production, Elsevier BV, 2016-09-09) [Article]
      Robust spatial information of evapotranspiration from multiple land cover types is deemed critical for several applications in agriculture and water balance studies. Energy balance models, used in association with satellite observations, are beneficial to map spatial variability of evapotranspiration which is mainly governed by different vegetation practices and local environmental conditions. This study utilize the Surface Energy Balance System model to estimate actual evapotranspiration and water scarcity footprints under complex landscape of Korean peninsula using Moderate-Resolution Imaging Spectroradiometer satellite data for a complete hydrological year of 2012. The modeled evapotranspiration was compared with flux tower measurements obtained from a subhumid cropland and temperate forest sites for the accuracy assessment. This accuracy comparison at daily scale had good agreement yielding reasonable coefficient of determination (0.72, 0.51), bias (0.41 mm day−1, 1.01 mm day−1) and root mean squared error (0.92 mm day−1, 1.53 mm day−1) at two observation (cropland, forest) sites, respectively. Furthermore, the monthly aggregated evapotranspiration from Surface Energy Balance System showed promising results than those of obtained from Moderate-Resolution Imaging Spectroradiometer based readymade global evapotranspiration product, i.e., MOD16, when both products were compared with unclosed and closed flux tower measurements. However, the variations in monthly evapotranspiration obtained from both products were significantly controlled by several climate factors and vegetation characteristics. Water stress mapping at regional and monthly scale also revealed strong contrast between the products of two approaches. Highest mean water stress (0.74) was observed for land use areas associated with evergreen forest and under sparsely vegetation condition by using estimated evapotranspiration from Surface Energy Balance System while an extreme mean water stress value of 0.56 by using end product of MOD16 evapotranspiration was raised from cropland regions. Overall, this study revealed the performance and suitability of two distinctive remote sensing approaches for characterizing the footprints of water fluxes in the Korean peninsula and provides a baseline for the policy makers to setup the sustainable use of existing water resources in this and other similar regions.
    • Adaptation to high current using low external resistances eliminates power overshoot in microbial fuel cells

      Hong, Yiying; Call, Douglas F.; Werner, Craig M.; Logan, Bruce E. (Biosensors and Bioelectronics, Elsevier BV, 2011-10) [Article]
      One form of power overshoot commonly observed with mixed culture microbial fuel cells (MFCs) is doubling back of the power density curve at higher current densities, but the reasons for this type of overshoot have not been well explored. To investigate this, MFCs were acclimated to different external resistances, producing a range of anode potentials and current densities. Power overshoot was observed for reactors acclimated to higher (500 and 5000. Ω) but not lower (5 and 50. Ω) resistances. Acclimation of the high external resistance reactors for a few cycles to low external resistance (5. Ω), and therefore higher current densities, eliminated power overshoot. MFCs initially acclimated to low external resistances exhibited both higher current in cyclic voltammograms (CVs) and higher levels of redox activity over a broader range of anode potentials (-0.4 to 0. V; vs. a Ag/AgCl electrode) based on first derivative cyclic voltammetry (DCV) plots. Reactors acclimated to higher external resistances produced lower current in CVs, exhibited lower redox activity over a narrower anode potential range (-0.4 to -0.2. V vs. Ag/AgCl), and failed to produce higher currents above ∼-0.3. V (vs. Ag/AgCl). After the higher resistance reactors were acclimated to the lowest resistance they also exhibited similar CV and DCV profiles. Our findings show that to avoid overshoot, prior to the polarization and power density tests the anode biofilm must adapt to low external resistances to be capable of higher currents. © 2011 Elsevier B.V.
    • Adapting a regularized canopy reflectance model (REGFLEC) for the retrieval challenges of dryland agricultural systems

      Houborg, Rasmus; McCabe, Matthew (Remote Sensing of Environment, Elsevier BV, 2016-08-20) [Article]
      A regularized canopy reflectance model (REGFLEC) is applied over a dryland irrigated agricultural system in Saudi Arabia for the purpose of retrieving leaf area index (LAI) and leaf chlorophyll content (Chll). To improve the robustness of the retrieved properties, REGFLEC was modified to 1) correct for aerosol and adjacency effects, 2) consider foliar dust effects on modeled canopy reflectances, 3) include spectral information in the red-edge wavelength region, and 4) exploit empirical LAI estimates in the model inversion. Using multi-spectral RapidEye imagery allowed Chll to be retrieved with a Mean Absolute Deviation (MAD) of 7.9 μg cm− 2 (16%), based upon in-situ measurements conducted in fields of alfalfa, Rhodes grass and maize over the course of a growing season. LAI and Chll compensation effects on canopy reflectance were largely avoided by informing the inversion process with ancillary LAI inputs established empirically on the basis of a statistical machine learning technique. As a result, LAI was reproduced with good accuracy, with an overall MAD of 0.42 m2 m− 2 (12.5%). Results highlighted the considerable challenges associated with the translation of at-sensor radiance observations to surface bidirectional reflectances in dryland environments, where issues such as high aerosol loadings and large spatial gradients in surface reflectance from bright desert soils to dark vegetated fields are often present. Indeed, surface reflectances in the visible bands were reduced by up to 60% after correction for such adjacency effects. In addition, dust deposition on leaves required explicit modification of the reflectance sub-model to account for its influence. By implementing these model refinements, REGFLEC demonstrated its utility for within-field characterization of vegetation conditions over the challenging landscapes typical of dryland agricultural regions, offering a means through which improvements can be made in the management of these globally important systems.
    • Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

      Feddal, I.; Ramdani, Amina; Taleb, Safia; Gaigneaux, E. M.; Batis, Narjès Harrouch; Ghaffour, NorEddine (Desalination and Water Treatment, Informa UK Limited, 2013-11-19) [Article]
      The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.
    • Adsorption characteristics of methane on Maxsorb III by gravimetric method

      Thu, Kyaw; Kim, Youngdeuk; Ismil, Azhar Bin; Saha, Bidyut Baran; Ng, Kim Choon (Applied Thermal Engineering, Elsevier BV, 2014-11) [Article]
      Adsorption characteristics of CH4 on the carbonaceous porous material is evaluated for possible application in adsorbed natural gas (ANG) system. Adsorption uptakes at assorted temperatures (25-80 °C) and pressures ranging from ambient to relatively high pressure i.e., 8.0 MPa are experimentally investigated. Surface characteristics such as pore surface area, micropore volume and pore size distribution of the adsorbent (Maxsorb III) are first evaluated using Classical Volumetric Method i.e., the manometric method with N2 gas adsorption at 77 K. The sorption measurements for methane, CH4 gas are carried out by thermogravimetric (TGA) method using magnetic suspension balance coupled with the automatic dosing system. The buoyancy measurements were first conducted using Helium gas as adsorbate. Buoyancy correction is applied to all sets of measured data and the specific uptake capacities (g/g of adsorbent) at various temperatures and pressures were calculated. The isotherm data were then fitted using Langmuir and Tòth isotherm models. It is observed that the data can be satisfactorily fitted using Tòth model with excellent fitting accuracy around 2.2% within the experimental range. The outcome of the present study especially the adsorption data at high pressures is applicable to accurate design and modeling of Adsorbed Natural Gas (ANG) systems. © 2014 Elsevier Ltd. All rights reserved.
    • Adsorption characteristics of water vapor on ferroaluminophosphate for desalination cycle

      Kim, Youngdeuk; Thu, Kyaw; Ng, Kim Choon (Desalination, Elsevier BV, 2014-07) [Article]
      The adsorption characteristics of microporous ferroaluminophosphate adsorbent (FAM-Z01, Mitsubishi Plastics) are evaluated for possible application in adsorption desalination and cooling (AD) cycles. A particular interest is its water vapor uptake behavior at assorted adsorption temperatures and pressures whilst comparing them to the commercial silica gels of AD plants. The surface characteristics are first carried out using N2 gas adsorption followed by the water vapor uptake analysis for temperature ranging from 20°C to 80°C. We propose a hybrid isotherm model, composing of the Henry and the Sips isotherms, which can be integrated to satisfactorily fit the experimental data of water adsorption on the FAM-Z01. The hybrid model is selected to fit the unusual isotherm shapes, that is, a low adsorption in the initial section and followed by a rapid vapor uptake leading to a likely micropore volume filling by hydrogen bonding and cooperative interaction in micropores. It is shown that the equilibrium adsorption capacity of FAM-Z01 can be up to 5 folds higher than that of conventional silica gels. Owing to the quantum increase in the adsorbate uptake, the FAM-Z01 has the potential to significantly reduce the footprint of an existing AD plant for the same output capacity. © 2014 Elsevier B.V.
    • Adsorption desalination: An emerging low-cost thermal desalination method

      Ng, K. C.; Thu, Kyaw; Kim, Youngdeuk; Chakraborty, Anutosh; Amy, Gary L. (Desalination, Elsevier, 2013-01) [Article]
      Desalination, other than the natural water cycle, is hailed as the panacea to alleviate the problems of fresh water shortage in many water stressed countries. However, the main drawback of conventional desalination methods is that they are energy intensive. In many instances, they consumed electricity, chemicals for pre- and post-treatment of water. For each kWh of energy consumed, there is an unavoidable emission of Carbon Dioxide (CO2) at the power stations as well as the discharge of chemically-laden brine into the environment. Thus, there is a motivation to find new direction or methods of desalination that consumed less chemicals, thermal energy and electricity.This paper describes an emerging and yet low cost method of desalination that employs only low-temperature waste heat, which is available in abundance from either the renewable energy sources or exhaust of industrial processes. With only one heat input, the Adsorption Desalination (AD) cycle produces two useful effects, i.e., high grade potable water and cooling. In this article, a brief literature review, the theoretical framework for adsorption thermodynamics, a lumped-parameter model and the experimental tests for a wide range of operational conditions on the basic and the hybrid AD cycles are discussed. Predictions from the model are validated with measured performances from two pilot plants, i.e., a basic AD and the advanced AD cycles. The energetic efficiency of AD cycles has been compared against the conventional desalination methods. Owing to the unique features of AD cycle, i.e., the simultaneous production of dual useful effects, it is proposed that the life cycle cost (LCC) of AD is evaluated against the LCC of combined machines that are needed to deliver the same quantities of useful effects using a unified unit of $/MWh. In closing, an ideal desalination system with zero emission of CO2 is presented where geo-thermal heat is employed for powering a temperature-cascaded cogeneration plant. © 2012 Elsevier B.V.
    • Adsorption desalination—Principles, process design, and its hybrids for future sustainable desalination

      Shahzad, Muhammad Wakil; Burhan, Muhammad; Ang, Li; Ng, Kim Choon (Emerging Technologies for Sustainable Desalination Handbook, Elsevier, 2018-05-03) [Book Chapter]
      The energy, water, and environment nexus is a crucial factor when considering the future development of desalination plants or industry in water-stressed economies. The new generation of desalination processes or plants has to meet the stringent environment discharge requirements and yet the industry remains highly energy efficient and sustainable when producing good potable water. Water sources, either brackish or seawater, have become more contaminated as feed while the demand for desalination capacities increases around the world. One immediate solution for energy efficiency improvement comes from the hybridization of the proven desalination processes to the newer processes of desalination: For example, the integration of the available heat-driven to adsorption desalination (AD) cycles where significant thermodynamic synergy can be attained when cycles are combined. For these hybrid cycles, a quantum improvement in energy efficiency as well as an increase in water production can be expected. The advent of MED with AD cycles, or simply called the MED-AD cycles, is one such example where seawater desalination can be pursued and operated in cogeneration with the electricity production plants: The hybrid desalination cycles utilize only the low exergy bled-stream at low temperatures, complemented with waste exhaust or renewable solar thermal heat at temperatures between 60°C and 80°C. In this chapter, the authors have reported their pioneered research on aspects of AD and related hybrid MED-AD cycles, both at theoretical models and experimental pilots. Using the cogeneration of electricity and desalination concepts, the authors examine the cost apportionment of fuel cost by the quality or exergy of the working steam for such cogeneration configurations.
    • An Adsorption Equilibria Model for Steady State Analysis

      Ismail, Azhar Bin; Sabnani, Karan M.; Ang, Li; Ng, Kim Choon (International Journal of Technology, International Journal of Technology, 2016-02-29) [Article]
      The investigation of adsorption isotherms is a prime factor in the ongoing development of adsorption cycles for a spectrum of advanced, thermally-driven engineering applications, including refrigeration, natural gas storage, and desalination processes. In this work, a novel semi-empirical mathematical model has been derived that significantly enhances the prediction of the steady state uptake in adsorbent surfaces. This model, a combination of classical Langmuir and a novel modern adsorption isotherm equation, allows for a higher degree of regression of both energetically homogenous and heterogeneous adsorbent surfaces compared to several isolated classical and modern isotherm models, and has the ability to regress isotherms for all six types under the IUPAC classification. Using a unified thermodynamic framework, a single asymmetrical energy distribution function (EDF) has also been proposed that directly relates the mathematical model to the adsorption isotherm types. This fits well with the statistical rate theory approach and offers mechanistic insights into adsorption isotherms.
    • Adsorption kinetics of propane on energetically heterogeneous activated carbon

      Ismail, Azhar Bin; Thu, Kyaw; Kandadai, Srinivasan; Ng, Kim Choon (Applied Thermal Engineering, Elsevier BV, 2014-11) [Article]
      The modeling of the adsorption isotherms and kinetics of the adsorbent+adsorbate pair is essential in simulating the performance of a pressurized adsorption chiller. In this work, the adsorption kinetics is analyzed from data measured using a magnetic suspension balance. The Statistical Rate Theory describes the Dubinin-Astakhov (DA) equation and extended to obtain an expression for transient analysis. Hence both the experimental excess equilibria data and the adsorption kinetics data may then be fitted to obtain the necessary parameters to fit the curves. The results fit the data very well within 6% of the error of regression. © 2014 Elsevier Ltd.
    • Adsorption-Desalination Cycle

      Chakraborty, Anutosh; Thu, Kyaw; Saha, Bidyut Baran; Ng, K. C. (Lior/Advances in Water Desalination, Wiley-Blackwell, 2012-10-24) [Book Chapter]
    • Advanced adsorption cooling cum desalination cycle: A thermodynamic framework

      Chakraborty, Anutosh; Thu, Kyaw; Ng, K. C. (Volume 4: Energy Systems Analysis, Thermodynamics and Sustainability; Combustion Science and Engineering; Nanoengineering for Energy, Parts A and B, ASME International, 2011) [Conference Paper]
      We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property surfaces of adsorbent-adsorbate system and the adsorption interaction potential between them. Employing the proposed formulations, the coefficient of performance (COP) and overall performance ratio (OPR) of adsorption cycle are computed for various pore widths of solid adsorbents. These results are compared with experimental data for verifying the proposed thermodynamic formulations. It is found from the present analysis that the COP and OPR of adsorption cooling cum desalination cycle is influenced by (i) the physical characteristics of adsorbents, (ii) characteristics energy and (iii) the surface-structural heterogeneity factor of adsorbent-water system. The present study confirms that there exists a special type of adsorbents having optimal physical characteristics that allows us to obtain the best performance.
    • Advanced characterization of dissolved organic matter released by bloom-forming marine algae

      Rehman, Zahid Ur; Jeong, Sanghyun; Tabatabai, S. Assiyeh Alizadeh; Emwas, Abdul-Hamid M.; Leiknes, TorOve (DESALINATION AND WATER TREATMENT, Informa UK Limited, 2017-06-01) [Article]
      Algal organic matter (AOM), produced by marine phytoplankton during bloom periods, may adversely affect the performance of membrane processes in seawater desalination. The polysaccharide fraction of AOM has been related to (bio)fouling in micro-filtration and ultrafiltration, and reverse osmosis membranes. However, so far, the chemical structure of the polysaccharides released by bloom-forming algae is not well understood. In this study, dissolved fraction of AOM produced by three algal species (Chaetoceros affinis, Nitzschia epithemoides and Hymenomonas spp.) was characterized using liquid chromatography–organic carbon detection (LC-OCD) and fluorescence spectroscopy. Chemical structure of polysaccharides isolated from the AOM solutions at stationary phase was analyzed using proton nuclear magnetic resonance (H-NMR). The results showed that production and composition of dissolved AOM varied depending on algal species and their growth stage. AOM was mainly composed of biopolymers (BP; i.e., polysaccharides and proteins [PN]), but some refractory substances were also present.H-NMR spectra confirmed the predominance of carbohydrates in all samples. Furthermore, similar fingerprints were observed for polysaccharides of two diatom species, which differed considerably from that of coccolithophores. Based on the findings of this study,H-NMR could be used as a method for analyzing chemical profiles of algal polysaccharides to enhance the understanding of their impact on membrane fouling.
    • An advanced online monitoring approach to study the scaling behavior in direct contact membrane distillation

      Lee, Jung Gil; Jang, Yongsun; Fortunato, Luca; Jeong, Sanghyun; Lee, Sangho; Leiknes, TorOve; Ghaffour, NorEddine (Journal of Membrane Science, Elsevier BV, 2017-10-12) [Article]
      One of the major challenges in membrane distillation (MD) desalination is scaling, mainly CaSO4 and CaCO3. In this study, in order to achieve a better understanding and establish a strategy for controlling scaling, a detailed investigation on the MD scaling was performed by using various analytical methods, especially an in-situ monitoring technique using an optical coherence tomography (OCT) to observe the cross-sectional view on the membrane surface during operation. Different concentrations of CaSO4, CaCO3, as well as NaCl were tested separately and in different mixed feed solutions. Results showed that when CaSO4 alone was employed in the feed solution, the mean permeate flux (MPF) has significantly dropped at lower volume concentration factor (VCF) compared to other feed solutions and this critical point was observed to be influenced by the solubility changes of CaSO4 resulting from the various inlet feed temperatures. Although the inlet feed and permeate flow rates could contribute to the initial MPF value, the VCF, which showed a sharp MPF decline, was not affected. It was clearly observed that the scaling on the membrane surface due to crystal growth in the bulk and the deposition of aggregated crystals on the membrane surface abruptly appeared close to the critical point of VCF by using OCT observation in a real time. On the other hand, NaCl + CaSO4 mixed feed solution resulted in a linear MPF decline as VCF increases and delayed the critical point to higher VCF values. In addition, CaCO3 alone in feed solution did not affect the scaling, however, when CaSO4 was added to CaCO3, the initial MPF decline and VCF met the critical point earlier. In summary, calcium scaling crystal formed at different conditions influenced the filtration dynamics and MD performances.
    • Advanced organic and biological analysis of dual media filtration used as a pretreatment in a full-scale seawater desalination plant

      Jeong, Sanghyun; Vollprecht, Robert; Cho, Kyungjin; Leiknes, TorOve; Vigneswaran, Saravanamuthu; Bae, Hyokwan; Lee, Seockheon (Desalination, Elsevier BV, 2016-02-19) [Article]
      Dual media filter (DMF) is being used as a primary pretreatment to remove particulate foulants at seawater desalination plants. However, many plants experience organic and biological fouling. The first part of this paper focuses on the monitoring of organic and biological foulants using advanced analytical techniques to optimize functioning of DMF at Perth Seawater Desalination Plant (PSDP) in Western Australia. In addition, microbial community analysis in DMF filtered seawater, and on DMF media (DMF-M) and cartridge filter (CF) was conducted using terminal restriction fragment length polymorphism (T-RFLP) and 454-pyrosequencing. In the full-scale DMF system, the bacterial community structure was clustered along with the filtration time and sampling positions. For the DMF effluent samples, the bacterial community structure significantly shifted after 4 h of filtration time, which corresponded with the permeability reduction trend. The dominant bacterial communities in the DMF effluent were OTU 13 (Phaeobacter) and OTU 19 (Oceaniserpentilla). The different biofilm-forming bacteria communities were found in the biofilm samples on DMF-M and CF. In the second part of the study, semi-pilot scale DMF columns were operated on-site under same operating conditions used in PSDP. It demonstrated the advantage of operating DMF at the biofiltration mode for improving the reduction of biofoulants. © 2016 Elsevier B.V.
    • Advanced Polymeric and Organic–Inorganic Membranes for Pressure-Driven Processes

      Le, Ngoc Lieu; Phuoc, Duong; Nunes, Suzana Pereira (Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, Elsevier BV, 2017-02-13) [Book Chapter]
      The state-of-the-art of membranes for reverse osmosis, nanofiltration, and gas separation is shortly reviewed, taking in account the most representative examples currently in application. Emphasis is also done on recent developments of advanced polymeric and organic–inorganic materials for pressure-driven processes. Many of the more recent membranes are not only polymeric but also contain an inorganic phase. Tailoring innovative materials with organic and inorganic phases coexisting in a nanoscale with multifunctionalization is an appealing approach to control at the same time diffusivity and gas solubility. Other advanced materials that are now being considered for membrane development are organic or organic–inorganic self-assemblies, metal-organic frameworks, and different forms of carbon fillers.
    • Advanced treatment of acrylic fiber manufacturing wastewater with a combined microbubble-ozonation/ultraviolet irradiation process

      Zheng, Tianlong; Zhang, Tao; Wang, Qunhui; Tian, Yanli; Shi, Zhining; Smale, Nicholas; Xu, Banghua (RSC Adv., Royal Society of Chemistry (RSC), 2015) [Article]
      This work investigated the effectiveness of a combination of microbubble-ozonation and ultraviolet (UV) irradiation for the treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under reactor condition (ozone dosage of 48 mg L-1, UV fluence rate of 90 mW cm-2, initial pH of 8.0, and reaction time of 120 min), the biodegradability (represented as BOD5/CODcr) of the wastewater improved from 0.18 to 0.47. This improvement in biodegradability is related to the degradation of alkanes, aromatic compounds, and other bio-refractory organic compounds. The combination of microbubble-ozonation and UV irradiation synergistically improved treatment efficiencies by 228%, 29%, and 142% for CODcr, UV254 removal and BOD5/CODcr respectively after 120 min reaction time, as compared with the sum efficiency of microbubble-ozonation alone and UV irradiation alone. Hydroxyl radical production in the microbubble-ozonation/UV process was about 1.8 times higher than the sum production in microbubble-ozonation alone and UV irradiation alone. The ozone decomposition rate in the combined process was about 4.1 times higher than that in microbubble-ozonation alone. The microbubble-ozonation/UV process could be a promising technique for the treatment of bio-refractory organics in the acrylic fiber manufacturing industry. © 2015 Royal Society of Chemistry.
    • Algal blooms: an emerging threat to seawater reverse osmosis desalination

      Villacorte, Loreen O.; Tabatabai, S. Assiyeh Alizadeh; Dhakal, N.; Amy, Gary L.; Schippers, Jan Cornelis; Kennedy, Maria Dolores (Desalination and Water Treatment, Informa UK Limited, 2014-08-04) [Article]
      Seawater reverse osmosis (SWRO) desalination technology has been rapidly growing in terms of installed capacity and global application over the last decade. An emerging threat to SWRO application is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in SWRO plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of various desalination plants to avoid irreversible fouling of downstream SWRO membranes. This article summarizes the current state of SWRO technology and the emerging threat of algal blooms to its application. It also highlights the importance of studying the algal bloom phenomena in the perspective of seawater desalination, so proper mitigation and preventive strategies can be developed in the near future. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.
    • Anaerobic bioleaching of metals from waste activated sludge

      Meulepas, Roel J W; Gonzalez-Gil, Graciela; Teshager, Fitfety Melese; Witharana, Ayoma; Saikaly, Pascal; Lens, Piet Nl L (Science of The Total Environment, Elsevier BV, 2015-05) [Article]
      Heavy metal contamination of anaerobically digested waste activated sludge hampers its reuse as fertilizer or soil conditioner. Conventional methods to leach metals require aeration or the addition of leaching agents. This paper investigates whether metals can be leached from waste activated sludge during the first, acidifying stage of two-stage anaerobic digestion without the supply of leaching agents. These leaching experiments were done with waste activated sludge from the Hoek van Holland municipal wastewater treatment plant (The Netherlands), which contained 342μgg-1 of copper, 487μgg-1 of lead, 793μgg-1 of zinc, 27μgg-1 of nickel and 2.3μgg-1 of cadmium. During the anaerobic acidification of 3gdry weightL-1 waste activated sludge, 80-85% of the copper, 66-69% of the lead, 87% of the zinc, 94-99% of the nickel and 73-83% of the cadmium were leached. The first stage of two-stage anaerobic digestion can thus be optimized as an anaerobic bioleaching process and produce a treated sludge (i.e., digestate) that meets the land-use standards in The Netherlands for copper, zinc, nickel and cadmium, but not for lead.