| 1. |
- Ali, Aamer, et al.
(författare)
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Progress in module design for membrane distillation
- 2024
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Ingår i: Desalination. - : Elsevier. - 0011-9164 .- 1873-4464. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- There have been tremendous advances in membrane distillation (MD) since the concept was introduced in 1961: new membrane designs and process configurations have emerged, and its commercial viability has been evaluated in several pilot-scale studies. However, its high energy consumption has hindered its commercialization. One of the most promising ways to overcome this obstacle is to develop more energy-efficient membrane modules. The MD research community has therefore developed diverse new module configurations for hollow fiber and flat sheet membranes that increase the thermal energy efficiency of MD by minimizing thermal polarization, increasing mass transfer across the membrane, and improving heat recovery from the condensed vapor. This review summarizes the progress that has been made in the design of hollow fiber and flat sheet membrane modules for MD applications. It begins with a brief introduction to MD and its configurations before describing developments in module fabrication and highlighting key areas where further research is needed.
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| 2. |
- Byhlin, Henric, et al.
(författare)
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Influence of adsorption and concentration polarisation on membrane performance during ultrafiltration of a non-ionic surfactant
- 2003
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Ingår i: Desalination. - 1873-4464. ; 151:1, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Surfactants are present in almost all aqueous solutions-either as additives for different purposes, or because they occur naturally. Because of the common occurrence of surfactants in process water it is important to know how they behave in membrane processes. Ultrafiltration membranes allow almost complete passage of surfactant monomers, but reject micelles almost completely. Concentration polarisation during ultrafiltration of surfactant solutions is therefore mainly influenced by the presence of micelles. Operating parameters, e.g. the transmembrane pressure and the concentration of surfactant, as well as the pure water flux of the membrane, have a marked influence on the performance of hydrophilic membranes, as shown in this investigation. A distinct difference between the interaction of a non-ionic surfactant with hydrophilic and hydrophobic membranes was observed. The hydrophobic membrane showed a flux reduction already at concentrations below the critical micelle concentration (CMC), whereas no flux reduction was observed for a hydrophilic membrane with the same nominal molecular weight cut-off, below the CMC.
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| 3. |
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| 4. |
- Eriksson, Eva, 1973-, et al.
(författare)
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Metals in greywater : Sources, presence and removal efficiencies
- 2009
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164 .- 1873-4464. ; 248:1-3, s. 271-278
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Tidskriftsartikel (refereegranskat)abstract
- To date, risk assessment for greywater reuse systems has almost exclusively been focussed on pathogenic microorganisms and conventional water quality parameters. Little is known about the risks from micropollutants present in greywater, nor about the potential for greywater treatment systems to act as barriers for micropollutants. In this paper, the sources, presence and potential fate of cadmium, mercury, lead, and nickel in onsite greywater treatment systems are investigated. Annual metal loads from bathroom greywater are small in comparison with typical municipal wastewater loads but still do not always meet environmental quality standards for surface waters. This study shows that onsite treatment may remove a third to a half of lead, mercury and nickel from bathroom greywater but showed no significant removal of cadmium. Geochemical modelling indicates that metals should not pose a problem for reuse in toilet flushing, irrigation and clothes washing. Rather, the major potential problems associated with the presence of metals in greywater are related to the issue of sludge disposal.
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| 5. |
- Eriksson, Eva, 1973-, et al.
(författare)
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Potential priority pollutants in sewage sludge
- 2008
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164 .- 1873-4464. ; 226:1-3, s. 371-388
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Tidskriftsartikel (refereegranskat)abstract
- Sewage sludge has been used as fertilizer for agricultural land over a long time. This is part of a sustainable practice utilizing and recycling the macronutrients back to land. During the last decades, questions have been raised concerning the risks related to heavy metals and xenobiotic organic compounds (XOCs) present in the sludge. Application on land used for agriculture is, therefore, not socially acceptable in some countries, e.g., Sweden. In this study, literature reviews showed that 541 XOCs potentially could be present in sewage sludge due to their presence in e.g. construction materials, pharmaceuticals, personal care products etc. 192 compounds have been quantified in sewage sludge, which indicate that, although many XOCs have been measured in sludge, there are potentially a vast number of compounds present that have not been analyzed for yet. In a hazard identification of the quantified compounds using their inherent properties and environmental fate it was shown that 99 XOCs could be classified as being hazardous with regard to the solid phase and 23 were found to be priority pollutants in the subsequent hazard assessment. The final selected priority pollutants can act as indicators when assessing sludge quality. They were compared with European legislations and discussed in regard for pointing out the need for mitigation such as substitution. Furthermore, the potential need for implementation of sludge treatment trains in order to meet the society's needs was addressed.
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| 6. |
- Eriksson, Eva, 1973-, et al.
(författare)
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Risk assessment of Xenobiotics in stormwater discharged to Harrestrup Å, Denmark
- 2007
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164 .- 1873-4464. ; 215:1-3, s. 187-197
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Tidskriftsartikel (refereegranskat)abstract
- Surface waters are highly manipulated in many cities in Europe, and the flow is largely impacted by discharges of stormwater and combined sewer overflow. Toxicity tests shown adverse effects in some of these recipients due to the presence of xenobiotic organic carbons (XOCs). Harrestrup Å, situated in the City of Copenhagen, is one of these recipients, where biotest using algae showed measurable toxicity in eight samples taken in 2003. Twenty-five different XOCs were quantified in the same samples. The present study aimed at identifying the most relevant XOCs out of these 25 to be selected for further analysis with respect to potential source control options.Fourteen XOCs (56%) were identified to constitute a potential hazard based on the RICH evaluation (Ranking and Identification of Chemical Hazards), while 9 XOCs (36%) were found to constitute a hazard towards the aquatic ecosystem based on an environmental-concentration/predicted-no-effect-concentration-quotient. The quantified levels did, however, fulfil the Danish and European surface water quality criteria (QC) and environmental quality standards (ESQ). Thus, although the QC and ESQ are met there is an actual risk due to stormwater-related pollutants. This clearly illustrates that there is a need for monitoring the stormwater quality in order to protect the ecosystems. It also shows that actions are needed to implement source control options and emission barriers.Twelve XOCs were selected for further evaluation of possible source control option to be implemented in order to improve the water quality. These are five pesticides (diuron, glyphosate, isoproturon, MCPA, terbutylazine), 4 PAHs (acenaphthene, fluoranthene, fluorene, pyrene), 3 others (LAS, nonylphenol and dinitro-o-cresol).
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| 7. |
- Essalhi, Mohamed, et al.
(författare)
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Improvement of nanostructured electrospun membranes for desalination by membrane distillation technology
- 2021
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Ingår i: Desalination. - : Elsevier. - 0011-9164 .- 1873-4464. ; 510
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Tidskriftsartikel (refereegranskat)abstract
- A systematic study is carried out to determine the optimum electrospinning preparation condition to prepare an adequate electrospun nanofibrous membrane (ENM) for direct contact membrane distillation (DCMD). A structural properties investigation of ENM was carried out because of the significant impact of its architectural structure, nanofiber diameter, inter-fiber space and ENM thickness, on DCMD performance. The morphology, hydrophobicity, mechanical properties, crystallinity and DCMD desalination were investigated. A long-term DCMD experiment (100h) was carried out using 30 g/L NaCl aqueous solution, both in the feed and permeate side of the optimum ENM membrane to evaluate its potential to produce drinkable water in case of lack of distilled water, for instance in a remote area, emergency situation, and/or portable system. In this case, drinkable water could be produced after 28 h with a permeate flux of 57.5 kg/m2.h and a salt rejection factor greater than 99.9%. Another long-term DCMD experiment (65 h) was conducted using 30 g/L NaCl aquesous solution as feed but at a higher temperature and distilled water as permeate to evaluate the desalination stability, wettability and scaling of the optimum ENM. A permeate flux of 58.5 kg/m2.h was obtained with a salt rejection factor greater than 99.9%.
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| 8. |
- Falth, F, et al.
(författare)
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Ultrafiltration of effluents front chlorine-free, kraft pulp bleach plants
- 2001
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Ingår i: Desalination. - 1873-4464. ; 133:2, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafiltration has proven to be a useful technology for treating alkaline bleach plant filtrates in sulphite pulp mills. In this investigation the treatment of seven alkaline filtrates from kraft pulp mills were studied. The results include high fluxes and fair, or even good, removal of organic, as well as inorganic, substances. The flux seems to depend on the concentration of the bleach plant filtrate rather than its origin. The factor with the largest impact on flux is conductivity, i.e., the concentration of the low-molecular-weight inorganic substances. The retention of organic substances varies depending on the type of filtrate and the water management system of the mill. The retention is highest when treating filtrates from the first alkaline stage from traditional ECF mills. Filtrates from modem ECF and TCF mills contain a larger fraction of low-molecular-weight substances, which are not retained as efficiently. The treatment not only reduces the organic content of the filtrates but also increases the fraction that is biodegradable. The membranes retain a rather large fraction of the multi-valent ions, while the monovalent ions are let through.
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| 9. |
- Gutierrez, G., et al.
(författare)
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Production of vegetable oil in milk emulsions using membrane emulsification
- 2009
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164 .- 1873-4464. ; 245:1-3, s. 631-638
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Konferensbidrag (refereegranskat)abstract
- The production of emulsions using milk as the continuous phase has a number of applications of interest from the food industry's point of view. In addition, producing an emulsion with a narrow drop size distribution is interesting since their increased stability could avoid Oswald ripening and creaming. Membrane emulsification is a novel technique which helps to obtain a narrower distribution compared to other emulsification techniques such as homogenizers or ultrasound. Moreover the use of membrane emulsification may reduce the energy cost. The food industry is interested in reducing the use of food additives, both to save money and increase consumer acceptance. Therefore the aim of this work was to investigate the use of the intrinsic emulsifying capacity of milk proteins to act as stabilizers for oil droplets produced by membrane emulsification. Using tubular SPG membrane (4.8 mu m pore diameter) in recirculation mode, at dispersed phase fluxes of either 5 L/hm(2) or 50 L/hm(2), a stable final emulsion of 30% w/w oil was obtained. The fat globule size distribution was more bimodal at higher oil concentrations and at the higher flux.
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| 10. |
- Hamawand, I., et al.
(författare)
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Desalination of salty water using vacuum spray dryer driven by solar energy
- 2017
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Ingår i: Desalination. - : Elsevier. - 0011-9164 .- 1873-4464. ; 404, s. 182-191
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses evaporation under vacuum condition with the aid from solar energy and the recovered waste heat from the vacuum pump. It is a preliminary attempt to design an innovative solar-based evaporation system under vacuum. The design details, equipment required, theoretical background and work methodology are covered in this article. Theoretically, based on the energy provided by the sun during the day, the production rate of pure water can be around 15 kg/m2/day. Assumptions were made for the worst case scenario where only 30% of the latent heat of evaporation is recycled and the ability of the dark droplet to absorb sun energy is around 50%. Both the waste heat from the pump and the heat collected from the photovoltaic (PV) panels are proposed to raise the temperature of the inlet water to the system to its boiling point at the selected reduced pressure.
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