Air gap membrane distillation for hypersaline brine concentration: Operational analysis of a full-scale module–New strategies for wetting mitigation

Schwantes, R.; Bauer, Lorenz; Chavan, Ketan S.; Dücker, D.; Felsmann, Clemens; Pfafferott, Jens

doi:10.1016/j.desal.2018.06.012

Cited by 45 publications

(37 citation statements)

References 44 publications

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“…Also, the permeate quality decreased as the salinity of the feed (and therefore that of the leak) increased. This effect was also shown by Schwantes et al [30]. To better assess this matter, the membrane leak ratio was calculated and compared for the different modules (Figure 6).…”

Section: Resultssupporting

confidence: 75%

“…However, they reported larger values than in lab-scale experiments, as also done by Ruiz-Aguirre et al, [29] using a similar module but with simulated seawater (0.6 M). Finally, Schwantes et al [30] studied an AGMD module adapted with an active draining of the air gap by low pressure air blowing using a range of concentration on the feed between 0 g·kg −1 and 240 g·kg −1 . Although the study was focused on the characterization of flux, GOR and thermal efficiency, permeate conductivity values were shown.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, a Solar Spring module and two different Aquastill modules were used to study the quality of permeate considering different feed concentrations in a range including high salinity, to test whether these commercial modules are suitable for industrial implementation. These modules have been fully characterized in terms of permeate production and energy efficiency [30,31,32], but extensive information on permeate quality has not been provided yet.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

2019

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In this work, the salinity of permeate obtained with membrane distillation (MD) in pilot scale systems was analyzed. Experiments were performed with three different spiral-wound commercial modules, one from Solar Spring with 10 m2 surface membrane area and two from Aquastill with 7.2 and 24 m2. Intermittent operation meant that high permeate conductivity was measured in the beginning of each experiment, which was gradually decreasing until reaching a constant value (3–143 µS·cm−1 for seawater feed). The final quality reached did not depend on operating conditions, only the time it took to reach it. This can be because the permeate flux dilutes the minimal feed leak taking place through pinholes in the membranes. Larger feed leak through the membrane was observed when operating in vacuum-enhanced air-gap MD configuration (V-AGMD), which is compatible with this explanation. However, for the increase of feed leak with salinity (up to 1.8 M), a conclusive explanation cannot be given. Pore wetting due to crystallization is discarded because the high permeate quality was recovered after washing with distilled water. More studies at higher salinities and also at membrane level are required to investigate this.

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Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

2019

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“…However, the fraction of conductive heat passed through the membrane is also comparably higher leading to a potentially lower thermal efficiency in modules with significant heat recovery and especially at higher salinities above 100 g NaCl/kg. There is enough evidence in research to acknowledge that the quality of distillate can, furthermore, be compromised by so called wetting phenomena and that these phenomena are enhanced when there is liquid on both sides of the membrane [14,49]. In DCMD this is unavoidable per se und must, therefore, be considered a disadvantage.…”

Section: Methodsmentioning

confidence: 99%

Characterization and Assessment of a Novel Plate and Frame MD Module for Single Pass Wastewater Concentration–FEED Gap Air Gap Membrane Distillation

et al. 2019

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Membrane distillation (MD) is an up and coming technology for concentration and separation on the verge of reaching commercialization. One of the remaining boundaries is the lack of available full-scale MD modules and systems suitable to meet the requirements of potential industrial applications. In this work a new type of feed gap air gap MD (FGAGMD) plate and frame module is introduced, designed and characterized with tap water and NaCl–H2O solution. The main feature of the new channel configuration is the separation of the heating and cooling channel from the feed channel, enabling a very high recovery ratio in a single pass. Key performance indicators (KPIs) such as flux, gained output ratio (GOR), recovery ratio and thermal efficiency are used to analyze the performance of the novel module concept within this work. A recovery rate of 93% was reached with tap water and between 32–53% with salt solutions ranging between 117 and 214 g NaCl/kg solution with this particular prototype module. Other than recovery ratio, the KPIs of the FGAGMD are similar to those of an air gap membrane distillation (AGMD) channel configuration. From the experimental results, furthermore, a new MD KPI was defined as the ratio of heating and cooling flow to feed flow. This RF ratio can be used for optimization of the module design and efficiency.

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“…Also shown in Fig. 9 are results of Schwantes et al [44], who proposed an alternative AGMD strategy for high salinity feed treatment based on sparging a constant low air flow inside the gap (resulting in maximum 40 mbar above atmospheric pressure). This was demonstrated as an efficient way of draining the gap and avoiding water contact between the feed channel and the gap through the membrane pores, thus reducing membrane wetting.…”

Section: Feedc [M]mentioning

confidence: 98%

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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Air gap membrane distillation for hypersaline brine concentration: Operational analysis of a full-scale module–New strategies for wetting mitigation

Cited by 45 publications

References 44 publications

Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

Evaluation of Permeate Quality in Pilot Scale Membrane Distillation Systems

Characterization and Assessment of a Novel Plate and Frame MD Module for Single Pass Wastewater Concentration–FEED Gap Air Gap Membrane Distillation

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

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