Electrochemical water softening in a diaphragm electrolyzer

Authors

DOI:

https://doi.org/10.15587/1729-4061.2017.96120

Keywords:

water softening, diaphragm electrolyzer, active reaction, oxidation-reduction potential

Abstract

The results of studies in electrochemical softening of water in a diaphragm electrolyzer with inert anodes and a porous diaphragm were presented. It was shown that the most significant degree of softening of water at the lowest current and electric power consumptions was observed when water was fed to the anode chambers and moved in parallel flows in the electrode chambers. The total hardness of natural water was reduced to 1.4–1.6 mmole/dm3, alkalinity to 3.8–4.3 mmole/dm3, pH by 0.3–0.6 and acidity practically did not change. The recommended process scheme for water softening involves parallel movement of catholyte and anolyte streams in the electrolyzer at a ratio of their consumptions (7–8):(3–2) and their separate extraction from the electrode chambers. Catholyte is filtered to remove insoluble hardness salts and mixed with anolyte. The degree of water softening is regulated only by changing the strength of direct current applied to the electrodes. The technology makes it possible to completely abandon the use of chemical reagents, simultaneously stabilize and disinfect softened water and avoid secondary contamination of water with chemicals. The design of an industrial monopolar electrolyzer with an inactive diaphragm for electrochemical change of pH and Eh was developed. The electrolyzer features a solid anode and a perforated cathode or perforated electrodes closely pressed against the diaphragm. The softening technology is advisable to use for local water preparation for production operations and before softening hard water with ion-exchange filters or electrodialyzers. The developed technology of water softening and purification has been introduced at a number of enterprises in Slovakia and Ukraine, in particular, for industrial water treatment in galvanic plants and flour mills.

Author Biographies

Viktor Fylypchuk, National University of Water and Environmental Engineering Soborna str., 11, Rivne, Ukraine, 33028

Doctor of Technical Sciences, Professor

Department of labour protection and life safety

Leonid Fylypchuk, National University of Water and Environmental Engineering Soborna str., 11, Rivne, Ukraine, 33028

PhD, Associate Professor

Department of automation, electrical and computer-integrated technologies

References

  1. Frog, B., Pervov, A. (2014). Vodopodgotovka [Water conditioning]. Moscow: Publishers Association building universities, 512.
  2. Van der Bruggen, B., Goossens, H., Everard, P. A., Stemgee, K., Rogge, W. (2009). Cost-benefit analysis of central softening for production of drinking water. Journal of Environmental Management, 91 (2), 541–549. doi: 10.1016/j.jenvman.2009.09.024
  3. Cuda, P., Pospisil, P., Tenglerova, J. (2006). Reverse osmosis in water treatment for boilers. Desalination, 198 (1-3), 41–46. doi: 10.1016/j.desal.2006.09.007
  4. Nanda, D., Tung, K.-L., Hsiung, C.-C., Chuang, C.-J., Ruaan, R.-C., Chiang, Y.-C. et. al. (2008). Effect of solution chemistry on water softening using charged nanofiltration membranes. Desalination, 234 (1-3), 344–353. doi: 10.1016/j.desal.2007.09.103
  5. Entezari, M., Tahmasbi, M. (2009). Water softening by combination of ultrasound and ion exchange. Ultrasonics Sonochemistry, 16 (3), 356–360. doi: 10.1016/j.ultsonch.2008.09.008
  6. Rogov, V. M., Filipchuk, V. L. (1989). Elektrokhimicheskaya tekhnologiya izmeneniya svoystv vody [The electrochemical technology is changing the properties of water]. Lviv: Vishcha School, 127.
  7. Gabrielli, C., Maurin, G., Francy-Chausson, H., Thery, P., Tran, T. T. M., Tlili, M. (2006). Electrochemical water softening: principle and application. Desalination, 201 (1-3), 150–163. doi: 10.1016/j.desal.2006.02.012
  8. Zhi, S., Zhang, S. (2014). A novel combined electrochemical system for hardness removal. Desalination, 349, 68–72. doi: 10.1016/j.desal.2014.06.023
  9. Malakootian, M., Mansoorian, H. J., Moosazadeh, M. (2010). Performance evaluation of electrocoagulation process using iron-rod electrodes for removing hardness from drinking water. Desalination, 255 (1-3), 67–71. doi: 10.1016/j.desal.2010.01.015
  10. Zeppenfeld, K. (2011). Electrochemical removal of calcium and magnesium ions from aqueous solutions. Desalination, 277 (1-3), 99–105. doi: 10.1016/j.desal.2011.04.005
  11. Hasson, D., Shemer, H., Semiat, R. (2015). Removal of scale-forming ions by a novel cation-exchange electrochemical system – A review. Desalination and Water Treatment, 57 (48-49), 23147–23161. doi: 10.1080/19443994.2015.1098806
  12. Park, J.-S., Song, J.-H., Yeon, K.-H., Moon, S.-H. (2007). Removal of hardness ions from tap water using electromembrane processes. Desalination, 202 (1-3), 1–8. doi: 10.1016/j.desal.2005.12.031
  13. Seo, S.-J., Jeon, H., Lee, J. K., Kim, G.-Y., Park, D., Nojima, H. et. al. (2010). Investigation on removal of hardness ions by capacitive deionization (CDI) for water softening applications. Water Research, 44 (7), 2267–2275. doi: 10.1016/j.watres.2009.10.020
  14. Zaslavschi, I., Shemer, H., Hasson, D., Semiat, R. (2013). Electrochemical CaCO3 scale removal with a bipolar membrane system. Journal of Membrane Science, 445, 88–95. doi: 10.1016/j.memsci.2013.05.042
  15. Demidova, Y. M., Shinkevich, E. O., Laptev, A. G. (2010). Use of a resource-saving technology in water treatment systems. Thermal Engineering, 57 (8), 657–661. doi: 10.1134/s0040601510080057
  16. Bagrii, V. A., Chebotaryova, R. D., Bashtan, S. Y., Remez, S. V., Goncharuk, V. V. (2008). Softening of calcium-hydrocarbonate water in a flow-through electrolyzer with a filtrating cartridge. Journal of Water Chemistry and Technology, 30 (2), 100–104. doi: 10.3103/s1063455x08020069
  17. Hasson, D., Sidorenko, G., Semiat, R. (2010). Calcium carbonate hardness removal by a novel electrochemical seeds system. Desalination, 263 (1-3), 285–289. doi: 10.1016/j.desal.2010.06.036
  18. Zito, R. (2011). Electrochemical Water Processing. John Wiley & Sons, 314. doi: 10.1002/9781118104675
  19. Filipchuk, V. L., Filipchuk, L. V. (2016). Zastosuvanya gaziv dlya regulyuvannya okisno-vidnovnih vlastivostey vody [The uze of gases for regulation redox properties of water]. Journal of Engineering Academy of Ukraine, 1, 178–183.

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Published

2017-04-25

How to Cite

Fylypchuk, V., & Fylypchuk, L. (2017). Electrochemical water softening in a diaphragm electrolyzer. Eastern-European Journal of Enterprise Technologies, 2(6 (86), 48–55. https://doi.org/10.15587/1729-4061.2017.96120

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Section

Technology organic and inorganic substances