Dual benefits of immobilized carbonic anhydrase: Enhancing water quality and reducing carbon footprint in desalination processes

Jacob Rubel, Dharmjeet Madhav, Veerle Vandeginste, Philippe Tob

https://doi.org/10.5004/po2024127

Dual benefits of immobilized carbonic anhydrase: enhancing water quality and reducing carbon footprint in desalination processes

Jacob Rubel¹, Dharmjeet Madhav¹, Veerle Vandeginste¹, Philippe Tob²*

¹KU Leuven, Campus Brugge, Department of Materials Engineering, 8200 Bruges, Belgium
²Aqvita SRL, B1050 Brussels, Belgium

*Corresponding author

https://doi.org/10.5004/po2024127

ABSTRACT

The low mineral content in water produced by desalination processes can pose health concerns for those in water scarce regions where it is the primary means of supplier drinkable water. Vital minerals like calcium and magnesium are important to reintroduce to these water supplies via remineralization processes. The conventional approach for the remineralization of water is to contact demineralized water with natural Mg and Ca containing rocks. However, this process is slow and not well suited to the industrial scale. Newer innovative methods apply CO₂ to generate carbonic acid in water in order to speed up the dissolution of these minerals. This not only serves to remineralize the water, but also act as a CO₂ sink. Carbonic anhydrase (CA), an enzyme that catalyzes the reversible conversion of carbon dioxide and water into bicarbonate and protons, presents a promising addition to accelerate the dissolution of carbonate salts by speeding up the conversion of CO₂ into carbonic acid. This study aims to immobilize CA on solid supports to enhance its stability, reusability, and dissolution efficiency. Investigation into immobilization on a textile support using chitosan proved successful achieving 91% activity recovery and a CA loading of 0.661 mg CA/g textile. This method for CA immobilization was then slightly scaled up and used in a continuous remineralization setup. The results showed an improvement in magnesium dissolution from magnesite rock of more than 300% compared to the control setup without active enzyme. This technology developed here could improve cost-effectiveness of CO₂ based remineralization solutions for producing high-quality mineral water from desalinated water, addressing global water sustainability challenges.

Keywords: Desalination; Post-treatment; Magnesium; Carbon footprint; CO₂ capture; Remineralization