Open Access Open Access  Restricted Access Subscription Access

Influence of operating conditions and membrane fouling on water flux during seawater desalination using air gap membrane distillation

Duong Cong Hung, Huynh Thai Nguyen, Pham Manh Thao, Trinh Thi En, Luong Trung Son

Abstract


Membrane distillation (MD) has emerged as a promising process for seawater desalination applications to augment fresh water supply in remote coastal areas. Amongst four basic MD configurations, air gap membrane distillation (AGMD) exhibits the highest thermal efficiency, and thus is the most used configuration for small-scale seawater desalination. In this study, the influences of operating conditions and membrane fouling on water flux of a lab-scale AGMD process with actual seawater feed were systematically investigated. The experimental results demonstrated strong impacts of feed temperature, circulation rates, and membrane fouling on the process water flux. Increasing feed temperature exponentially raised water flux but also aggravated polarization effects of the AGMD process. Elevating water circulation rates, particularly of the feed stream, helped alleviate polarization effects, hence improving the process water flux. During the AGMD process of raw seawater feed, the accumulation of organic matters on the membrane reduced its active surface for water evaporation, increased polarization effects, and therefore significantly reduced the process water flux. Pretreatment of the seawater feed by 0.45 mm paper filters removed organic foulants from the feed, and hence helped sustain the water flux of the AGMD process at water recoveries up to 70 %. When the process water recovery exceeded 70 %, water flux rapidly dropped owing to the precipitation of sparingly soluble salts (e.g. CaSO4, CaCO3) on the membrane. Subsequent cleaning the fouled membrane using vinegar removed nearly all foulants from the membrane surface to restore the membrane hydrophobicity, and thus the process water flux. The results reported in this study manifest that seawater AGMD desalination can be a practical process to supply drinking water to small and remote communities in Vietnam.

Keywords. Membrane distillation (MD), air gap membrane distillation (AGMD), seawater desalination, membrane fouling, membrane fouling mitigation.

Keywords


Membrane distillation (MD), air gap membrane distillation (AGMD), seawater desalination, membrane fouling, membrane fouling mitigation.

References


P. Wang and T. -S. Chung. Recent advances in membrane distillation processes: Membrane development, configuration design and application exploring, Journal of Membrane Science, 474, 39-56 (2015).

A. Subramani and J. G. Jacangelo. Emerging desalination technologies for water treatment: A critical review, Water Research, 75, 164-187 (2015).

H. C. Duong, P. Cooper, B. Nelemans, T.Y. Cath, and L.D. Nghiem. Evaluating energy consumption of membrane distillation for seawater desalination using a pilot air gap system, Separation and Purification Technology, 166, 55-62 (2016).

H. C. Duong, P. Cooper, B. Nelemans, and L. D. Nghiem. Optimising thermal efficiency of direct contact membrane distillation via brine recycling for small-scale seawater desalination, Desalination, 374, 1-9 (2015).

H. C. Duong, A. R. Chivas, B. Nelemans, M. Duke, S. Gray, T. Y. Cath, and L. D. Nghiem. Treatment of RO brine from CSG produced water by spiral-wound air gap membrane distillation - A pilot study, Desalination, 366, 121-129 (2015).

H. C. Duong, M. Duke, S. Gray, T. Y. Cath, and L. D. Nghiem. Scaling control during membrane distillation of coal seam gas reverse osmosis brine, Journal of Membrane Science, 493, 673-682 (2015).

A. Alkhudhiri, N. Darwish, and N. Hilal. Membrane distillation: A comprehensive review, Desalination, 287, 2-18 (2012).

K. W. Lawson and D. R. Lloyd. Membrane distillation, Journal of Membrane Science, 124, 1-25 (1997).

H. C. Duong, M. Duke, S. Gray, P. Cooper, and L. D. Nghiem. Membrane scaling and prevention techniques during seawater desalination by air gap membrane distillation, Desalination, 397, 92-100 (2016).

J. Phattaranawik, R. Jiraratananon, and A.G. Fane. Heat transport and membrane distillation coefficients in direct contact membrane distillation, Journal of Membrane Science, 212, 177-193 (2003).

E. Drioli, A. Ali, and F. Macedonio. Membrane distillation: Recent developments and perspectives, Desalination, 356, 56-84 (2015).

M. Rebhun, S. Meir, and Y. Laor. Using Dissolved Humic Acid To Remove Hydrophobic Contaminants from Water by Complexation-Flocculation Process, Environmental Science & Technology, 32, 981-986 (1989).

L. D. Nghiem, F. Hildinger, F.I. Hai, and T. Cath. Treatment of saline aqueous solutions using direct contact membrane distillation, Desalination and Water Treatment, 32, 234-241 (2011).

L. D. Nghiem and T. Cath. A scaling mitigation approach during direct contact membrane distillation, Separation and Purification Technology, 80, 315-322 (2011).

J. Ge, Y. Peng, Z. Li, P. Chen, and S. Wang. Membrane fouling and wetting in a DCMD process for RO brine concentration, Desalination, 344, 97-107 (2014).


Full Text: PDF

Refbacks

  • There are currently no refbacks.