A novel combined electrochemical system for hardness removal

Zhi, Suli; Zhang, Shuting

doi:10.1016/j.desal.2014.06.023

Cited by 49 publications

(18 citation statements)

References 21 publications

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“…It can be also observed that the pH is lower as Q decreases, indicating a better efficiency for low Q. That behaviour is logical because at high Q the feed water passes too fast through the electrochemical reactor leading to an insufficient treatment [17,29]. That means a lower applied charge per cubic meter (Coulombs m -3 ) and therefore a lower OHconcentration at every instant.…”

Section: Effect Of the Flow Ratementioning

confidence: 96%

Electrochemical softening of concentrates from an electrodialysis brackish water desalination plant: Efficiency enhancement using a three-dimensional cathode

Sanjuán

Benavente

García-García

et al. 2019

Separation and Purification Technology

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Please cite this article as: I. Sanjuán, D. Benavente, V. García-García, E. Expósito, V. Montiel, Electrochemical softening of concentrates from an Electrodialysis brackish water desalination plant: efficiency enhancement using a three-dimensional cathode., Separation and Purification Technology (2018), doi: https://doi. AbstractThe electrochemical softening method to remove hardness from water has not been applied in desalination practice due to a high cathodic area requirement. In this work, the use of a 3D stainless steel wool cathode is proposed to overcome this technical limitation. An extensive comparison between the 3D cathode and a 2D Ti mesh has been presented, showing higher hardness removal for the 3D one. Experiments have been conducted with waters similar to concentrates derived from a brackish water treatment by electrodialysis. In addition, the method has been proved to be efficient for different water compositions in terms of hardness, alkalinity or the presence of an antiscalant. The main influencing parameters (flow rate and current density) have been studied and it can be concluded that lower flow rates (below 1.2 L h -1 ) give rise to a better efficiencies and 100 A m -2 is the optimum current density. Moreover, the precipitate was characterised by SEM, EDX and XRD showing that Ca 2+ is removed as calcite and aragonite (CaCO 3 ), whereas Mg 2+ is precipitated as brucite (Mg(OH) 2 ).Finally, long-term experiments revealed that the 3D stainless steel cathode has a better performance than the 2D Ti mesh, but only at short times. Keywords: Electrochemical softening, hardness removal, three-dimensional electrodes, electroprecipitation, concentrate, wastewater treatment. V Volt V cell Cell voltage VMD Vacuum membrane distillation XRD X-ray diffraction Highlights  3D cathodes provide an enhancement in the electrochemical softening method. A comparison between a 2D and a 3D cathode is reported for water hardness removal. Long-term electroprecipitation experiments assess the 3D cathode behaviour with time. Water hardness is removed by precipitation of calcite, aragonite, and brucite.

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Section: Effect Of the Flow Ratementioning

confidence: 96%

Electrochemical softening of concentrates from an electrodialysis brackish water desalination plant: Efficiency enhancement using a three-dimensional cathode

Sanjuán

Benavente

García-García

et al. 2019

Separation and Purification Technology

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“…It has been established that the greatest degree of water softening in a flow-type electrolyzer at the lowest consumption of electric power was observed when water was fed to the anode chamber, a part of water was filtered into the cathode chamber and when water was moved in parallel flows in the electrode chambers at a ratio of catholyte and anolyte flows (7)(8): . Due to the treatment of the entire water flow in the anode chamber and pH of the mixture of catholyte and anolyte removed from the electrode chambers, disinfection and stabilization of the softened water occured.…”

Section: Discussionmentioning

confidence: 99%

“…To reduce cathode incrustation, combined treatment of water in electrolyzers with soluble and insoluble anodes is recommended which facilitates electrode purification from the hardness salts [8]. A separate use of soluble metal anodes in an electrolyzer is recommended for electrocoagulation of hardness salts [9].…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

“…The recommended process scheme for softening involves the parallel movement of catholyte and anolyte streams in the electrolysis cell in a consumption ratio (7)(8): and their separate extraction from the electrode chambers. Catholyte is then filtered to remove insoluble hardness salts and mixed with anolyte.…”

Section: Softening Of Water Under Different Patterns Of Water Flowmentioning

confidence: 99%

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Electrochemical water softening in a diaphragm electrolyzer

Fylypchuk

2017

EEJET

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“…A variety of water treatment technologies are applied to soften the circulating water, such as the addition of acidic detergents and other chemicals, (Neveux et al 2016) exchange resins, reverse osmosis, nanofiltration and electrodialysis etc. (Almarzooqi et al 2014;Zhi & Zhang 2014). However, these technologies have drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Research on performance optimization and mechanism of electrochemical water softening applied by pulse power supply

Wang

et al. 2021

Water Science and Technology

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In order to promote the application of electrochemical water softening technology in industrial circulating cooling water systems, electric field type, cathode structure and solution residence time are selected for optimization analysis of electrochemical water softening device. The experimental results show that the water softening performance per unit area of mesh cathode is better than that of plate cathode. In addition, the softening amount per unit area of the mesh cathode can be further increased when the high-frequency (HF) power supply is applied. When the HF power supply is applied, the softening amount per unit area is 158.58 g/m2·h−1 more than that the direct current power supply is applied. In order to explore the growth mechanism of calcium carbonate, micro-analysis technology and high-speed bubble photography technology are used. The results show that the bubbles escape along the longitudinal direction of the electrode plate, and the main growth direction of calcium carbonate growth is consistent with the escape direction of the bubble, that is, the bubbles grow along the longitudinal direction of the electrode plate. The special structure of the diamond-shaped mesh cathode facilitates the growth of calcium carbonate crystals.

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A novel combined electrochemical system for hardness removal

Cited by 49 publications

References 21 publications

Electrochemical softening of concentrates from an electrodialysis brackish water desalination plant: Efficiency enhancement using a three-dimensional cathode

Electrochemical softening of concentrates from an electrodialysis brackish water desalination plant: Efficiency enhancement using a three-dimensional cathode

Electrochemical water softening in a diaphragm electrolyzer

Research on performance optimization and mechanism of electrochemical water softening applied by pulse power supply

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