Electrodialysis for upgrading water streams in Kraft pulp mills

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School of Chemical Technology | Doctoral thesis (article-based) | Defence date: 2024-11-14
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Authors

Date

2024

Department

Biotuotteiden ja biotekniikan laitos
Department of Bioproducts and Biosystems

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Mcode

Degree programme

Language

en

Pages

66 + app. 52

Series

Aalto University publication series DOCTORAL THESES, 232/2024

Abstract

The sustainability of water resources has emerged as a relevant driving force in our economy, particularly for large industries. This concern is especially pertinent to water and energy-intensive mills, such as cellulose pulp industrial plants. Water scarcity is becoming increasingly prevalent, and prioritizing its consumption, along with adhering to stringent environmental regulations, makes this issue challenging to address. It remains essential to properly treat substantial volumes of effluents in these plants before discharging them, to minimize the environmental impact of such operations. To achieve this, mechanical and biological treatments are typically employed. Other water treatment technologies are often cost-prohibitive. However, in certain cases, it remains necessary to incorporate additional treatments for achieving water recirculation and chemical recovery. Otherwise, detrimental non-process elements could accumulate in the pulping process if water is recirculated. Alternatively, salts may be disposed of in water bodies or landfills unless they are converted into useful chemicals. Among various water treatment options, electrodialysis (ED) is a versatile technology capable of demineralizing effluent and internal streams, storing and recovering energy, and transforming salts into useful chemicals for reuse. However, ED encounters compatibility issues when treating effluents from cellulose pulp industrial plants, as organics in these streams cause fouling problems. In this thesis, additive manufacturing was used to improve hydraulics of ED systems, while power electronics was employed to address the fouling issue, enhancing the compatibility of ED for upgrading the water resources of Kraft pulp mills. New techniques allow the application of polarity reversal pulses on the order of kHz. By applying high-frequency pulses, turbulence mediated by electric fields are promoted, overcoming the system's limits imposed by the depletion of ions on the surface of the membranes, reducing not only fouling occurrence, but also membrane area requirement. ED and its variants were tested at both laboratory and pilot scale in industrial facilities, in conjunction with a device called the Asymmetric Bipolar Switch (ABS), which enabled the application of high-frequency pulses. Two variations of electrodialysis were tested at pilot scale, when coupled with the ABS, demonstrating improved operation by decreasing fouling over time and increasing productivity. The operations proved to be more robust when using the high-frequency pulses during tests spanning several weeks, enhancing ED compatibility. This advancement represents a significant step in surpassing the technical and cost barriers associated with electrodialysis in the effluent treatment of cellulose pulp industrial plants.

Description

Supervising professor

Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland

Thesis advisor

Joutsimo, Olli, Dr., Bioforest SpA., Chile

Keywords

kraft pulping, high-frequency electrodialysis reversal, effluent treatment, wastewater recovery, desalination

Other note

Parts

  • [Publication 1]: Gonzalez-Vogel, A., & Rojas, O.J. (2019) Asymmetric bipolar switch device for electrochemical processes. AIP Advances 9, 085011.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-201909035058
    DOI: 10.1063/1.5115412 View at publisher
  • [Publication 2]: Gonzalez-Vogel, A., & Rojas, O.J. (2020) Exploiting electroconvective vortices in electrodialysis with high-frequency asymmetric bipolar pulses for desalination in overlimiting current regimes. Desalination 474, 114190.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202002031964
    DOI: 10.1016/j.desal.2019.114190 View at publisher
  • [Publication 3]: Gonzalez-Vogel, A., Moltedo, J.J, Quezada Reyes, R., Schwarz, A., & Rojas, O.J. (2021) High frequency pulsed electrodialysis of acidic filtrate in kraft pulping. Journal of Environmental Management 282, 111891.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-2021121510781
    DOI: 10.1016/j.jenvman.2020.111891 View at publisher
  • [Publication 4]: Gonzalez-Vogel, A., Felis-Carrasco, F., & Rojas, O.J. (2021) 3D Printed manifolds for improved flow management in electrodialysis operation for desalination. Desalination 505, 114996.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202103222413
    DOI: 10.1016/j.desal.2021.114996 View at publisher
  • [Publication 5]: Gonzalez-Vogel, A., Moltedo, J.J., & Rojas, O.J. (2021) Desalination by pulsed electrodialysis reversal: Approaching fully close-loop water systems in the forest products industry. Journal of Environmental Management 298, 113518.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202109028856
    DOI: 10.1016/j.jenvman.2021.113518 View at publisher

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https://urn.fi/URN:ISBN:978-952-64-2104-9

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[diss] Kemian tekniikan korkeakoulu / CHEM