Membrane fouling and wetting in a DCMD process for RO brine concentration

Ge, Ju; Peng, Yongbo; Li, Zhehao; Chen, Ping; Wang, Shaobin

doi:10.1016/j.desal.2014.03.017

Cited by 138 publications

(51 citation statements)

References 26 publications

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“…The slight reduction in membrane contact angle caused by tap water observed in this study was consistent with results reported by Ge et al [33]. In contrast, a significant decrease in the membrane contact angle was observed at the end of the DCMD process with CSG RO brine.…”

Section: Efficiency Of Various Cleaning Solutionssupporting

confidence: 80%

Scaling control during membrane distillation of coal seam gas reverse osmosis brine

Duong

Gray

Duke

et al. 2015

Journal of Membrane Science

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We systematically assess the efficiency of chemical cleaning and report a simple but elegant approach to control scaling during membrane distillation (MD) of brine from reverse osmosis (RO) treatment of coal seam gas (CSG) produced water. Results reported here show that increased feed water salinity and the permeation of CO2 from the feed solution resulted in only a small and gradual decrease in water flux. On the other hand, the precipitation of sparingly soluble salts on the membrane at high water recovery (>70%) led to a significant flux decline. Among the three chemical cleaning agents investigated, a reverse osmosis scale cleaning agent (denoted as MC3) was the most effective at restoring the water flux; however, MC3 cleaning was not able to completely remove scale deposits from the membrane and restore its surface hydrophobicity to the original value because of the complexation of scalants with CSG RO brine. The remaining scalants (i.e., silicates) reduced the membrane surface hydrophobicity and could possibly enhance concentration polarisation and act as seeding for further scale formation. Thus, a gradual decrease in MD performance with respect to both water flux and salt leakage was observed after each MC3 cleaning cycle. It was noted that the chemical cleaning agents themselves did not alter the hydrophobicity of the membrane; thus, the gradual decline in MD performance was attributed to the remaining scale deposits on the membrane after each cleaning cycle. Results reported here highlight the need to prevent membrane scaling and only use chemical cleaning as the last resort during MD treatment of CSG RO brine. Moreover, membrane scaling could be prevented by reducing concentration polarisation via limiting feed temperature and thus water flux. MD treatment of CSG RO brine with up to 80% water recovery without any observable membrane scaling was achieved at the feed temperature and the water flux of 35°C and 10L/m 2 h, respectively. AbstractWe systematically assess the efficiency of chemical cleaning and report a simple but elegant approach to control scaling during membrane distillation (MD) of brine from reverse osmosis (RO) treatment of coal seam gas (CSG) produced water. Results reported here show that increased feed water salinity and the permeation of CO 2 from the feed solution resulted in only a small and gradual decrease in water flux. On the other hand, the precipitation of sparingly soluble salts on the membrane at high water recovery (>70%) led to a significant flux decline. Among the three chemical cleaning agents investigated, a reverse osmosis scale cleaning agent (denoted as MC3) was the most effective at restoring the water flux; however, MC3 cleaning was not able to completely remove scale deposits from the membrane and restore its surface hydrophobicity to the original value because of the complexation of scalants with CSG RO brine. The remaining scalants (i.e., silicates) reduced the membrane surface hydrophobicity and could possibly enhance concentration polarisation and ...

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Section: Efficiency Of Various Cleaning Solutionssupporting

confidence: 80%

Scaling control during membrane distillation of coal seam gas reverse osmosis brine

Duong

Gray

Duke

et al. 2015

Journal of Membrane Science

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“…Generally, the presence of salt in the distillate can be attributed either to entrainment of fine liquid droplets by vapor molecules [51] or to membrane pore wetting [52]. It these setups, high salt concentration did not cause complete pore wetting because the permeate flux did not increase.…”

Section: Effect Of High Salinity Feed On Wettingmentioning

confidence: 99%

Wetting prevention in membrane distillation through superhydrophobicity and recharging an air layer on the membrane surface

Rezaei

Warsinger

Lienhard

et al. 2017

Journal of Membrane Science

126

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Although membrane distillation offers distinctive benefits in some certain areas, i.e., RO concentrate treatment, concentrating solutions in the food industry and solar heat utilization, the occurrence of wetting of the hydrophobic membrane hinders its potential industrial applications.Therefore, wetting prevention is a vital criterion for the treatment of solutions with lower surface tension than water. The present work examines the effect of recharging air bubbles on the membrane surface for the wetting incidence when a surfactant (sodium dodecyl sulfate, SDS) exists in a highly concentrated NaCl aqueous solution. This study shows that the presence of the air bubbles on the surface of the superhydrophobic membrane in a direct contact membrane distillation setup inhibited the occurrence of wetting (~100% salt rejection) even for high concentrations of the surface-active species (up to 0.8 mM SDS) in the feed solution while no undesirable influence on the permeate flux was observed. Introducing air into the feed side of the membrane displaces the liquid which partly tends to penetrate the macroporous structure with air bubbles and therefore increases the liquid entry pressure, and in addition, the simultaneous use of a superhydrophobic membrane enhances the solution contact angle.

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“…In addition, to sustain its separation functionality, MD requires the membrane pores to be dry. In seawater applications, organic matter and scale formed on the membrane surface can alter the membrane hydrophobicity, which may lead to liquid intrusion into the pores, and, subsequently, water flux reduction and deteriorated distillate quality [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Optimising thermal efficiency of direct contact membrane distillation by brine recycling for small-scale seawater desalination

Duong

Cooper

Nelemans³

et al. 2015

Desalination

118

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A technique to optimise thermal efficiency using brine recycling during direct contact membrane distillation (DCMD) of seawater was investigated. By returning the hot brine to the feed tank, the system water recovery could be increased and the sensible heat of the hot brine was recovered to improve thermal efficiency. The results show that in the optimal water recovery range of 20 to 60% facilitated by brine recycling, the specific thermal energy consumption of the process could be reduced by more than half. It is also noteworthy that within this optimal water recovery range, the risk of membrane scaling is negligible -DCMD of seawater at a constant water recovery of 70% was achieved for over 24. h without any scale formation on the membrane surface. In contrast, severe membrane scaling was observed when water recovery reached 80%. In addition to water recovery, other operating conditions such as feed temperature and water circulation rates could influence the process thermal efficiency. Increasing the feed temperature and reducing the circulation flow rates increased thermal efficiency. Increasing the feed temperature could also mitigate the negative effect of elevated feed concentration on the distillate flux, particularly at a high water recovery. Abstract:A technique to optimise thermal efficiency using brine recycling during direct contact membrane distillation (DCMD) of seawater was investigated. By returning the hot brine to the feed tank, the system water recovery could be increased and the sensible heat of the hot brine was recovered to improve thermal efficiency. The results show that in the optimal water recovery range of 20 to 60% facilitated by brine recycling, the specific thermal energy consumption of the process could be reduced by more than half. It is also noteworthy that within this optimal water recovery range, the risk of membrane scaling is negligible  DCMD of seawater at a constant water recovery of 70% was achieved for over 24 hours without any scale formation on the membrane surface. In contrast, severe membrane scaling was observed when water recovery reached 80%. In addition to water recovery, other operating conditions such as feed temperature and water circulation rates could influence the process thermal efficiency. Increasing the feed temperature and reducing the circulation flow rates increased thermal efficiency. Increasing the feed temperature could also mitigate the negative effect of elevated feed concentration on the distillate flux, particularly at a high water recovery.

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Membrane fouling and wetting in a DCMD process for RO brine concentration

Cited by 138 publications

References 26 publications

Scaling control during membrane distillation of coal seam gas reverse osmosis brine

Scaling control during membrane distillation of coal seam gas reverse osmosis brine

Wetting prevention in membrane distillation through superhydrophobicity and recharging an air layer on the membrane surface

Optimising thermal efficiency of direct contact membrane distillation by brine recycling for small-scale seawater desalination

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