Rabin Desalination Laboratory

• The Rabin Desalination Laboratory, named in honor of the late prime minister of Israel, Yitzhak Rabin, was founded in June 1996.
• RDL focus on research of water desalination science, technology, engineering, and management.
  • Research of selected topics, navigated by Israel and regional needs
  • Collaborate with experts from academia and industry worldwide
  • Promote scientific and practical interdisciplinary research programs.
  • Support Israeli industry to excel and prosper in the global water market

Recent projects, summarized in the listed publications, are presented herein.

Upgrading current desalination processes

High recovery RO desalination of brackish water

Currently, the maximum recovery achievable in a brackish water RO desalination plant (80-85%) is constrained by the supersaturation level that can be maintained with an antiscalant. Significant environmental and cost benefits would be generated by elevating the water recovery levels of RO plants. The increased recovery level lowers the unit cost of the water product and reduces the significant costs involved in meeting concentrate disposal regulations. It was shown that water recovery can be increased to above 90-95% by RO processing of the concentrate, after precipitating and separating the scaling salts. However, precipitation of the scaling salts is hindered by the inhibitory effect of the antiscalant. Therefore, a simple technique for precipitating the scale is by air bubbling was developed.

• Lisitsin, D. Hasson R. Semiat. The potential of CO₂ stripping for pretreating brackish and wastewater desalination feeds. Desalination 222(1-3) (2008) 50–58. https://doi.org/10.1016/j.desal.2007.02.063 
• Segev, D. Hasson R. Semiat. Improved high recovery brackish water desalination process based on fluidized bed air stripping. Desalination 281 (2011) 75-79. https://doi.org/10.1016/j.desal.2011.07.043 
• Hasson, R. Segev, D. Lisitsin, B. Liberman, R. Semiat. High recovery brackish water desalination process devoid of precipitation chemicals. Desalination 283 (2011) 80-88. https://doi.org DOI: 10.1016/j.desal.2011.03.037 
• Segev, D. Hasson R. Semiat. Modeling CaCO₃ precipitation in fluidized bed CO₂ stripping desalination process. Desalination 311 (2013) 192-197. https://doi.org/10.1016/ j.desal.2012.11.024 

Re-mineralization and improved process based on micronized calcite dissolution

A widely used re-mineralization process consists of the dissolution of calcite particles by acidified desalinated water, by carbon dioxide or sulfuric acid, reintroducing bicarbonate alkalinity and calcium hardness to the water. Cumulative experimental evidence confirms the reliability of a kinetic model developed by Yamauchi et al. and Letterman et al. Analyzes of the main operational parameters affecting the minimum cost design of a hardening column were conducted.

An alternative process consists of calcite dissolution by the slurry flow of micron-size calcite particles with acidified desalinated water. Micron-size particles expose a contact area three orders of magnitude larger than that of millimeter-sized particles therefore, high dissolution rates are obtained. Extensive experimental results displayed the effects of acid concentration, slurry feed concentration, and dissolution contact time on the re-mineralization efficiency. A design model was developed and completely verified by pilot-scale experiments. Apart from the practical value of this work in providing a hitherto lacking design tool for novel technology. This work has the merit of being among the very few providing experimental confirmations to the theory describing reaction kinetics in a segregated flow system.

• Hasson, O. Bendrihem. Modeling remineralization of desalinated water by limestone dissolution. Desalination 190 (2006) 189-200. https://doi.org/10.1016/j.desal .2005.09.003
• Shemer, D. Hasson, R. Semiat, M. Priel, N. Nadav, A. Shulman, E. Gelman. Re-mineralization of desalinated water by limestone dissolution with carbon dioxide. Desalination and Water Treatment 51 (2013) 877-881. https://doi.org/10.1080/ 19443994.2012.694236
• Shemer, D. Hasson, R. Semiat. Design considerations of a packed calcite bed for hardening desalinated water. Industrial & Engineering Chemistry Research 52 (2013) 10549-10553. https://doi.org/10.1021/ie302975b
• Shemer, D. Hasson, R. Semiat. State-of-the-art review on post-treatment technologies. Desalination 356 (2015) 285-293. https://doi.org/ 10.1016/j.desal.2014.09.035
• Shemer, R. Semiat, D. Hasson. Re-mineralization of desalinated water using a mixture of CO₂ and H₂SO₄. Desalination 467 (2019) 170–174. https://doi.org/10.1016/ j.desal.2019.06.017
• Hasson, L. Fine, A. Sagiv, R. Semiat, H. Shemer. Modeling re-mineralization of desalinated water by micronized calcite dissolution. Environmental Science and Technology 1 (2017) 12481-12488.  DOI: 10.1021/ACS.est.7b03069

Viable re-mineralization processes for dosing magnesium to desalinated water

Re-mineralization of desalinated water with magnesium ions is currently under consideration. A simple easily controlled technique for adding magnesium ions to desalinated water consists of the dissolution of magnesia pellets in a packed bed by feed water slightly acidified with either carbon dioxide or sulfuric acid. A design model was developed and confirmed by experimental data covering a range of acid concentrations and contact times.

A second method of adding magnesium to desalinated water is by the dissolution of dolomite by acidified water. Dolomite re-mineralization has a marked advantage because this mineral is a double salt composed of CaCO₃ and MgCO₃ and its dissolution can provide both calcium and magnesium ions in a single process. Design models were developed for dolomite dissolution using CO₂ or H₂SO₄. The models enable confident evaluations of dolomite re-mineralization processes. Re-mineralization by H₂SO₄ seems to be the most attractive process alternative.

The newly developed process of re-mineralization of desalinated water by micronized calcite powder dissolution was extended to re-mineralization by micronized dolomite dissolution. Design models were developed and experimentally verified.

• Hasson, R. Semiat, H. Shemer, M. Priel, N. Nadav. Simple process for hardening desalinated water with Mg²⁺ ions. Desalination and Water Treatment 51 (2013) 924-929. https://doi.org/10.1021/acs.est.7b03069
• Schwartz, H. Shemer, D. Hasson, R. Semiat, R. Design model for magnesium ions re-mineralization of desalinated water by the dissolution of magnesia pellets. Desalination 373 (2015) 10-15. https://doi.org/10.1016/j.desal.2015.06.024
• Greiserman, D. Hasson, R. Semiat, H. Shemer. Kinetics of dolomite dissolution in a packed bed by acidified desalinated water. Desalination 396 (2016) 39-47. https://doi.org/10.1016/j.desal.2016.05.006
• Hasson, M. Greiserman, R. Semiat, H. Shemer. Theoretical and experimental study of micronized dolomite dissolution. Desalination and water treatment 143 (2019) 88-95. https://doi.org/10.5004/dwt.2019.23637

Modeling of osmotic processes

Power generation via pressure retarded osmosis (PRO) was explored based on a detailed two-dimensional finite-element (2-D-FEM) PRO model. The numerical model was used to determine the draw and feed crossflow velocities for maximizing peak power generation. Next, the dependence of PRO power generation on channel dimensions, membrane transport parameters were evaluated, followed by assessing the impact of frictional pressure losses and pumping and energy recovery device (ERD) efficiencies.

2D finite element CFD model and the common film model were used for the analysis of forward-osmosis (FO) performance data was examined to assess the merits of conclusions derived from the above approaches regarding the characterization of membrane and support layer resistances to water and salt permeation.

A comprehensive and time-dependent 2D model using the finite element method (FEM) was developed to account for different versions of the backwash (BW) cleaning method for RO membranes. The optimal setup of backwash cleaning methods was determined by analyzing the parameters affecting BW flux: accumulated volume during the process, and permeate salinity.

• Sagiv, W. Xu, P.D. Christofides, Y. Cohen, R. Semiat. Evaluation of osmotic energy extraction via FEM modeling and exploration of PRO operational parameter space. Desalination 401 (2017) 120-133. https://doi.org/10.1016/j.desal.2016.09.015
• Sagiv, P.D. Christofides, Y. Cohen, R. Semiat. On the analysis of FO mass transfer resistances via CFD analysis and film theory. Journal of Membrane Science 495 (2015) 198-205. https://doi.org/10.1016/j.memsci.2015.08.022
• Sagiv, A. Zhu, P.D. Christofides, Y. Cohen, R. Semiat. Analysis of forward-osmosis desalination via two-dimensional FEM model. Journal of Membrane Science 464 (2014) 161-172. https://doi.org/10.1016/j.memsci.2014.04.001
• Sagiv, R. Semiat. Finite element analysis of forward-osmosis process using NaCl solutions. Journal of Membrane Science 379(1-2) (2011) 86-96. https://doi.org/10.1016/j.memsci.2011.05.042
• Sagiv, R. Semiat. Modeling of backwash cleaning methods for RO membranes. Desalination 261(3) (2010) 338-346. https://doi.org/10.1016/j.desal.2010.04.054
• Sagiv, R. Semiat. Parameters affecting backwash variables of RO membranes. Desalination 261(3) (2010) 347-353. https://doi.org/10.1016/j.desal.2010.04.012

Wastewater purifications- Donnan dialysis

Donnan dialysis is inions separation process utilizing ion-exchange membranes. In this process, a solution of target ionic species is held in a feed compartment separated by an ion-exchange membrane from a receiver compartment holding a counter ion stripping solution of high concentration. Migration of counter-ions from the receiver compartment to the feed compartment induces an equivalent counter flow of target ions from the feed to the receiver compartment. The attractive features of Donnan dialysis lie in operational simplicity, low energy requirement, and no chemicals requirement. Evaluation of the potential of Donnan dialysis as a new water purification technique was carried out. Followed by an examination of a hybrid process for removal of nitrate from contaminated groundwater by coupling Donnan dialysis with electro-reduction.

• Hasson, A. Beck, A. Fingerman, F. Tachman, H. Shemer, R. Semiat. A simple model for characterizing a Donnan dialysis process. Industrial & Engineering Chemistry Research 53 (2014) 6094–6102. https://doi.org/10.1021/ie404291q 
• Ring, D. Hasson, H. Shemer, R. Semiat. Simple modeling of Donnan separation processes. Journal of Membrane Science 476 (2015) 348–355. https://doi.org/10.1016/ j.memsci.2014.12.001
• Hasson, R. Semiat, H. Shemer. Potential of Donnan dialysis water purification processes. Desalination and water treatment 69 (2017) 12-17. HTTPS:// doi.org/10.5004/dwt.2017.0689
• Shemer, A. Sagiv, R. Semiat, D. Hasson. Effects of the selectivity coefficient on the kinetics of Donnan separation. Desalination and water treatment 146 (2019) 1-7. https://doi.org/10.5004/dwt.2019.23776
• Breytus D. Hasson, R. Semiat, H. Shemer. Ion exchange membrane adsorption in Donnan dialysis. Separation and purification Technology 226 (2019) 252–258. https://doi.org/10.1016/j.seppur.2019.05.084
• Makeover, D. Hasson, Y. Huang, R. Semiat, H. Shemer. Electrochemical removal of nitrate from a Donnan dialysis waste stream. Water Science & Technology, 80(4) (2019) 727-736. https://doi.org/10.2166/wst.2019.314 
• Hasson, S. Ring, R. Semiat, H. Shemer. Simple modeling of Donnan separation processes: Single and multi-component feed solutions. Separation Science and Technology 55(6) (2020) 1216–1226. https://doi.org/10.1080/01496395.2019. 1586729 
• Makover, D. Hasson, R. Semiat, H. Shemer. Electrochemical removal of nitrate from high salinity waste stream in a continuous flow reactor. Journal of Environmental Chemical Engineering 8 (2020) 103727. https://doi.org/10.1016 /j.jece.2020.103727
• Breytus, D. Hasson, R. Semiat, H. Shemer. Removal of nitrate from groundwater by Donnan dialysis. Journal of Water Process Engineering 34 (2020) 101157. https://doi.org/10.1016/j.jwpe.2020.101157 
• Breytus, D. Hasson, R. Semiat, H. Shemer. Removal of nitrate in semi and fully continuous-flow Donnan dialysis systems. Separation and Purification Technology 250 (2020) 117249. https://doi.org/10.1016/j.seppur.2020.117249

Energy and environmental issues in desalination

The expedient solution to water scarcity worldwide is desalination. Nevertheless, common misconceptions of high cost, energy intensiveness, and negative ecological footprint hinder global implementation. The objective of the papers is to refute some unsubstantiated claims regarding the energy demand and environmental impacts of desalination. To date, worldwide chemical and biological monitoring programs show that brine discharge from desalination plants has localized minimal impacts on the marine environment. It was shown that properly sited, designed, and operated desalination plants contribute to reduced energy demand and environmental footprint.

• R. Semiat. Energy issues in desalination processes. Environ. Sci. Technol. 42(22) (2008) 8193–8201. https://doi.org/10.1021/es801330u 
• Miller, H. Shemer, R. Semiat. Energy and environmental issues in desalination. Desalination 366 (2015) 2-8. https://doi.org/10.1016/j.desal.2014.11.034
• Shemer, R. Semiat. Sustainable RO desalination – Energy demand and environmental impact. Desalination 424 (2017) 10-16. https://doi.org/ 10.1016/j.desal.2017.09.021

Electrochemical membrane system (ECM)

An electrolytic cell at which the ion-exchange membrane separates the cathode and anode compartments were investigated. In this configuration, the cathode serves only to create an alkaline environment for the precipitation of undesired ions such as scale-forming ions (calcium, magnesium, silica, etc’) heavy metals, and nutrients. Crystal seeds replace the cathode as precipitation surfaces. It was shown that using the ECM system, as much as 90% of the calcium in seawater was easily precipitated. Precipitation rate as high as 600-700 g/h m² cathode area was achieved, compared to 40-60 g/h m² in conventional electrochemical precipitation technology.

• Hasson, G. Sidorenko, R. Semiat. Low electrode area electrochemical scale removal system. Desalination and Water Treatment 31 (1-3) (2011) 35-41. https://doi.org/ 10.5004/dwt.2011.2389 
• Hasson, G. Sidorenko, R. Semiat. Calcium carbonate hardness removal by a novel electrochemical seeds system. Desalination 263 (1-3) (2010) 285-289. https://doi.org/10.1016/j.desal.2010.06.036
• Zaslavschi, H. Shemer, D. Hasson, R. Semiat. Electrochemical CaCO₃ scale removal with a bipolar membrane system. Journal of Membrane Science 445 (2013) 88-95. https://doi.org/10.1016/j.memsci.2013.05.042
• Gorni-Pinkesfeld, H. Shemer, D. Hasson, R. Semiat. Electrochemical removal of phosphate ions from treated wastewater. Industrial & Engineering Chemistry Research 52 (2013) 13795-13800. https://doi.org/10.1021/ie401930c
• Hasson, H. Shemer, R. Semiat. Removal of scale-forming ions by a novel cation exchange electrochemical system – A review. Desalination and water treatment 57 (2016) 23147-23161. https://doi.org/10.1080/19443994.2015.1098806 
• Gorni-Pinkesfeld, D. Hasson, R. Semiat, H. Shemer. Hybrid electrolysis–crystallization system for silica removal from aqueous solutions. Desalination 407 (2017) 41-45. https://doi.org/10.1016/j.desal.2016.12.014

High recovery Multi-Stage Flash (MSF) desalination

Thermal processes are more attractive for treating highly contaminated produced waters. Thermal-produced water processes are associated with calcium sulfate-containing solutions. A high-temperature low energy thermal process was applied, following partial removal of calcium ions via electrochemical membrane system. Calcium sulfate precipitates in three forms: gypsum (CaSO₄·2H₂O), hemihydrate (CaSO₄·½H₂O), and anhydrite (CaSO₄). Field data indicate that the temperature-solubility limits of the MSF process are dictated by hemihydrate. It was experimentally revealed that by reducing the calcium ion concentration it is possible to extend thermal desalination processes vastly benefit the economics.

• Lisitsin-Shmulevsky, X. Li, D. Hasson, H. Shemer, R. Semiat. Solubility limits of CaSO₄ polymorphs in seawater solutions. Desalination 475 (2020) 114200. https://doi.org/10.1016/j.desal.2019.114200
• Hasson, M. Shmulevsky-Lisitsin, R. Semiat, H. Shemer. High recovery MSF desalination process. Desalination and Water Treatment 106 (2018) 1-10. https://doi.org/10.5004/dwt.2018.22127

Nano-adsorbents

Immobilized adsorbent

Granular activated carbon was impregnated with a homogenous porous layer of magnetite (Fe₃O₄) nano-particles (< 4 nm). The adsorbent (nFe-GAC) exhibited high efficiency of phosphate, copper, and chromium removal. The mechanism included adsorption by the active sites on the magnetite surface, via ligand exchange mechanism, followed diffusion into the interior pores of the nano-magnetite layer. A new approach to the Thomas model was developed to better describe the dynamic of the continuous fixed-bed adsorption process. Reusability was demonstrated through successive fix-bed adsorption/regeneration cycles. The feasibility of a zero liquid discharge (ZLD) process, using the nFe-GAC for phosphate removal was demonstrated.

• Zach-Maor, R. Semiat, H. Shemer. Synthesis, performance, and modeling of immobilized nano-sized magnetite layer for phosphate removal. Journal of Colloid and Interface Science 357(2) (2011) 440-446. https://doi.org/10.1016/j.jcis.2011.01.021
• Zach-Maor, R. Semiat, H. Shemer. Removal of heavy metals by immobilized magnetite nano-particles. Desalination and Water Treatment 31 (2011) 64-70. https://doi.org/5004/dwt.2011.2369 
• Zach-Maor, R. Semiat, H. Shemer. Adsorption-desorption mechanism of phosphate by immobilized nano-sized magnetite layer: interface and bulk interactions. Journal of Colloid and Interface Science 363 (2011) 608-614. https://doi.org/10.1016 /j.jcis.2011.07.062
• Zach-Maor, R. Semiat, H. Shemer. Fixed bed phosphate adsorption by immobilized nano-magnetite matrix: experimental and a new modeling approach. Adsorption 17 (2011) 929-936. https://doi.org/10.1007/s10450-011-9371-1

 Suspended adsorbent

The use of micro-sized iron hydroxide adsorbents is a promising technique for the removal of inorganic pollutants from contaminated water. An adsorbent, exhibiting a hierarchical porous of aggregated iron oxy-hydroxide nano-particles (IOAs), resembling goethite, on a micrometer scale (15-50 mm) with a surface area of around 2,500 m²/g was developed. Results demonstrated the potential application of the IOAs as a renewable adsorbent, with the possible recovery of the pollutants, contributing to sustainable hybrid processes, the coupling of adsorption with ultrafiltration.

• Wei, S. Luo, R. Xiao, R. Khalfin, R. Semiat. Characterization and quantification of chromate adsorption by layered porous iron oxyhydroxide: An experimental and theoretical study. Journal of Hazardous Materials 338 (2017) 472-481. https://doi.org/10.1016/j.jhazmat.2017.06.001
• Wei, R. Semiat. Applying a modified Donnan model to describe the surface complexation of chromate to iron oxyhydroxide agglomerates with heteromorphous pores. Journal of Colloid and Interface Science 506 (2017) 66-75. https://doi.org/10.1016/j.jcis.2017.07.034
• Hilbrandt, H. Shemer, A. Ruhl, R. Semiat. M. Jekel, Comparing fine particulate iron hydroxide adsorbents for the removal of phosphate in a hybrid adsorption/ultrafiltration system. Separation and Purification Technology 221 (2019) 23-28. https://doi.org/10.1016/j.seppur.2019.03.044 
• Shemer, A. Amrush, R. Semiat, Reusability of iron oxyhydroxide agglomerates adsorbent for repetitive phosphate removal. Colloids and Surfaces A 579 (2019) 1-8. https://doi.org/10.1016/j.colsurfa.2019.123680
• Shemer, N. Melki-Dabush, R. Semiat. Removal of silica from brackish water by integrated adsorption/ultrafiltration process. Environmental Science and Pollution Research 26 (2019) 31623–31631. https://doi.org/10.1007/s11356-019-06363-9
• Wei, R. Semiat, H. Shemer. A hybrid iron oxyhydroxide agglomerates-ultrafiltration process for efficient removal of chromate. Environmental Technology. https://doi.org/10.1080/09593330.2020.1751728