Multi effect desalination and adsorption desalination (MEDAD): A hybrid desalination method
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
Permanent link to this recordhttp://hdl.handle.net/10754/563837
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AbstractThis paper presents an advanced desalination cycle that hybridizes a conventional multi-effect distillation (MED) and an emerging yet low-energy adsorption cycle (AD). The hybridization of these cycles, known as MED + AD or MEDAD in short, extends the limited temperature range of the MED, typically from 65 °C at top-brine temperature (TBT) to a low-brine temperature (LBT) of 40 °C to a lower LBT of 5 °C, whilst the TBT remains the same. The integration of cycles is achieved by having vapor uptake by the adsorbent in AD cycle, extracting from the vapor emanating from last effect of MED. By increasing the range of temperature difference (DT) of a MEDAD, its design can accommodate additional condensation-evaporation stages that capitalize further the energy transfer potential of expanding steam. Numerical model for the proposed MEDAD cycle is presented and compared with the water production rates of conventional and hybridized MEDs. The improved MEDAD design permits the latter stages of MED to operate below the ambient temperature, scavenging heat from the ambient air. The increase recovery of water from the seawater feed may lead to higher solution concentration within the latter stages, but the lower saturation temperatures of these stages mitigate the scaling and fouling effects. © 2014 Elsevier Ltd. All rights reserved.
CitationShahzad, M. W., Ng, K. C., Thu, K., Saha, B. B., & Chun, W. G. (2014). Multi effect desalination and adsorption desalination (MEDAD): A hybrid desalination method. Applied Thermal Engineering, 72(2), 289–297. doi:10.1016/j.applthermaleng.2014.03.064
JournalApplied Thermal Engineering
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Adsorption desalination—Principles, process design, and its hybrids for future sustainable desalinationShahzad, Muhammad Wakil; Burhan, Muhammad; Ang, Li; Ng, Kim Choon (Emerging Technologies for Sustainable Desalination Handbook, Elsevier BV, 2018-05-03) [Book Chapter]The energy, water, and environment nexus is a crucial factor when considering the future development of desalination plants or industry in water-stressed economies. The new generation of desalination processes or plants has to meet the stringent environment discharge requirements and yet the industry remains highly energy efficient and sustainable when producing good potable water. Water sources, either brackish or seawater, have become more contaminated as feed while the demand for desalination capacities increases around the world. One immediate solution for energy efficiency improvement comes from the hybridization of the proven desalination processes to the newer processes of desalination: For example, the integration of the available heat-driven to adsorption desalination (AD) cycles where significant thermodynamic synergy can be attained when cycles are combined. For these hybrid cycles, a quantum improvement in energy efficiency as well as an increase in water production can be expected. The advent of MED with AD cycles, or simply called the MED-AD cycles, is one such example where seawater desalination can be pursued and operated in cogeneration with the electricity production plants: The hybrid desalination cycles utilize only the low exergy bled-stream at low temperatures, complemented with waste exhaust or renewable solar thermal heat at temperatures between 60°C and 80°C. In this chapter, the authors have reported their pioneered research on aspects of AD and related hybrid MED-AD cycles, both at theoretical models and experimental pilots. Using the cogeneration of electricity and desalination concepts, the authors examine the cost apportionment of fuel cost by the quality or exergy of the working steam for such cogeneration configurations.
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Series Assembly of Microbial Desalination Cells Containing Stacked Electrodialysis Cells for Partial or Complete Seawater DesalinationKim, Younggy; Logan, Bruce E. (Environmental Science & Technology, American Chemical Society (ACS), 2011-07) [Article]A microbial desalination cell (MDC) is a new approach for desalinating water based on using the electrical current generated by exoelectrogenic bacteria. Previously developed MDCs have used only one or two desalination chambers with substantial internal resistance, and used low salinity catholytes containing a buffered or acid solution. Here we show that substantially improved MDC performance can be obtained even with a nonbuffered, saline catholyte, by using an electrodialysis stack consisting of 5 pairs of desalting and concentrating cells. When 4 stacked MDCs were used in series (20 total pairs of desalination chambers), the salinity of 0.06 L of synthetic seawater (35 g/L NaCl) was reduced by 44% using 0.12 L of anode solution (2:1). The resistive loss in the electrodialysis stack was negligible due to minimization of the intermembrane distances, and therefore the power densities produced by the MDC were similar to those produced by single chamber microbial fuel cells (MFCs) lacking desalination chambers. The observed current efficiency was 86%, indicating separation of 4.3 pairs of sodium and chloride ions for every electron transferred through the circuit. With two additional stages (total of 3.8 L of anolyte), desalination was increased to 98% salt removal, producing 0.3 L of fresh water (12.6:1). These results demonstrate that stacked MDCs can be used for efficient desalination of seawater while at the same time achieving power densities comparable to those obtained in MFCs. © 2011 American Chemical Society.