Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

Ruiz-Aguirre, A.; Andrés-Mañas, J.A.; Zaragoza, Guillermo

doi:10.3390/membranes9060069

Cited by 39 publications

(23 citation statements)

References 40 publications

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“…On the other hand, membrane distillation utilizes thermal energy to provide the driving pressure force, which does not deteriorate significantly for high salinity feed [9][10][11][12][13][14][15]. Additionally, supplementing the membrane distillation (MD) module with a vacuum pump on the distillate side, commonly known as vacuum membrane distillation (VMD), further improves the performance for extremely high salinity feed [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Long-Running Comparison of Feed-Water Scaling in Membrane Distillation

et al. 2020

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Membrane distillation (MD) has shown promise for concentrating a wide variety of brines, but the knowledge is limited on how different brines impact salt scaling, flux decline, and subsequent wetting. Furthermore, past studies have lacked critical details and analysis to enable a physical understanding, including the length of experiments, the inclusion of salt kinetics, impact of antiscalants, and variability between feed-water types. To address this gap, we examined the system performance, water recovery, scale formation, and saturation index of a lab-scale vacuum membrane distillation (VMD) in long-running test runs approaching 200 h. The tests provided a comparison of a variety of relevant feed solutions, including a synthetic seawater reverse osmosis brine with a salinity of 8.0 g/L, tap water, and NaCl, and included an antiscalant. Saturation modeling indicated that calcite and aragonite were the main foulants contributing to permeate flux reduction. The longer operation times than typical studies revealed several insights. First, scaling could reduce permeate flux dramatically, seen here as 49% for the synthetic brine, when reaching a high recovery ratio of 91%. Second, salt crystallization on the membrane surface could have a long-delayed but subsequently significant impact, as the permeate flux experienced a precipitous decline only after 72 h of continuous operation. Several scaling-resistant impacts were observed as well. Although use of an antiscalant did not reduce the decrease in flux, it extended membrane operational time before surface foulants caused membrane wetting. Additionally, numerous calcium, magnesium, and carbonate salts, as well as silica, reached very high saturation indices (>1). Despite this, scaling without wetting was often observed, and scaling was consistently reversible and easily washed. Under heavy scaling conditions, many areas lacked deposits, which enabled continued operation; existing MD performance models lack this effect by assuming uniform layers. This work implies that longer times are needed for MD fouling experiments, and provides further scaling-resistant evidence for MD.

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Section: Introductionmentioning

confidence: 99%

Long-Running Comparison of Feed-Water Scaling in Membrane Distillation

et al. 2020

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“…where PermC and FeedC are the concentration of the permeate and the feed, respectively, calculated from the correlation indicated in [39]. In addition, the membrane leak ratio was estimated as a measurement of how much feed passed through the membrane during the operation:…”

Section: Methodsmentioning

confidence: 99%

“…module and the AS26 module, respectively. Unfortunately, for higher feed salinities it was not possible to get a good statistical representation regarding measurements of the quality of the permeate in the experiments performed, due to the longer time (several hours) that it takes to obtain an acceptable stable value of the permeate conductivity when the flux is lower (see [39]). Thus, the SRF values are given for maximum concentration of 2.4 M in the AS7 module and 1.8 M in the AS26 module.…”

Section: Permeate Qualitymentioning

confidence: 99%

Performance increase of membrane distillation pilot scale modules operating in vacuum-enhanced air-gap configuration

et al. 2020

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This paper presents the first experimental evaluation at pilot scale of the operation of vacuum-enhanced air-gap membrane distillation (V-AGMD) using two commercial spiral-wound modules at Plataforma Solar de Almería's solar desalination test facilities. The main difference between the modules was the channel length (1.5 and 2.7 m) as a result of having different membrane surface area (7.2 m 2 and 25.9 m 2 respectively) and different number of envelopes. Suction of air from the gap improved the vapour transfer through the membrane pores and the performance of the modules was significantly increased in relation to common air-gap (AGMD) operational mode, especially in the treatment of high salinity feeds. Increases of up to 234% in permeate flux and decreases of 68% in specific thermal energy consumption were measured. Depending on the channel length of the modules, the effect of vacuum led to extreme permeate productivity (8.7 l h −1 m −2) in the shortest, or to extreme energy efficiency (49 kWh th m −3 , equivalent to a GOR of 13.5) in the longest. These are the best experimental performances obtained so far with pilot scale modules in membrane distillation. A similar heat recovery concept is pursued by the Dutch company Aquastill BV, who fabricates advanced spiral-wound air-gap membrane distillation (AGMD) modules. Their novelty is that they use several rolled envelopes forming a number of internal evaporation and cooling

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“…A spiral wound AGMD module manufactured by Solarspring ( Fig. 6) was tested with sodium chloride solutions ranging in concentration from 0 to 240 g/L NaCl in Germany [30,32]. The pilot unit distillate capacity was 25 L/h (Fig.…”

Section: For Concentration Of Hypersaline Brinesmentioning

confidence: 99%

Membrane distillation: recent technological developments and advancements in membrane materials

et al. 2021

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Membrane distillation (MD) is a novel desalination technology that has potential to produce distilled quality water from high salinity brine streams. The driving force for MD is the vapor pressure difference across a hydrophobic membrane resulting in transfer of water vapor from hot to cold side. This vapor contacts a cold surface and condenses to produce distillate. This paper reviews recent and/or multi-year research programs that focused on MD pilot or field testing. The various investigations concluded that while MD can produce distilled water quality, the energy efficiency remains the key bottleneck for future deployment of MD. Membrane wetting and fouling also presents key challenges for desalination due to both the high salinity and the presence of organics in the feed water. The authors contacted several MD vendors requesting updates on their latest products and technology developments. MD vendors with innovative module designs, some of which promise a step change in performance, have recently emerged on the market. In addition to water desalination, MD has a wide range of industrial applications such as hydrogen sulfide removal, the treatment of wastewater from the pharmaceutical, metal finishing industries, direct sewer mining, oily wastewater, and water recovery from flue gas. This paper also reviews novel membrane chemistries with emphasis on membranes prepared by phase inversion and electrospinning techniques to which nanomaterials have been added. The primary objectives in adding various nanomaterials (e.g., carbon nanotubes, graphene, silicon dioxide, fluorinated compounds) are to increase hydrophobicity (to reduce wetting) and increase mass transfer rates (to increase flux and lower cost).

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Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

Cited by 39 publications

References 40 publications

Long-Running Comparison of Feed-Water Scaling in Membrane Distillation

Long-Running Comparison of Feed-Water Scaling in Membrane Distillation

Performance increase of membrane distillation pilot scale modules operating in vacuum-enhanced air-gap configuration

Membrane distillation: recent technological developments and advancements in membrane materials

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