Advancing biological water treatment: Biodesalination and heavy metal remediation using immobilized algae

In an attempt to address the issue of water scarcity in a sustainable and eco-friendly way, the concept of biodesalination arises. Algae, which are widely exploited in the field of wastewater treatment, have also shown potential in desalinating water and capturing heavy metals. However, harvesting the algae culture post-treatment is challenging and makes the process unfeasible. This paper investigates the efficacy of immobilized algae that are easier to collect and control by reviewing ion and heavy metal capture mechanisms, immobilization techniques and media, and current applications in treating saline water and heavy metal pollution. Results show that immobilized algae are able to capture ions and heavy metals mainly through bio-adsorption and bio-absorption mechanisms. Additionally, the most popular immobilization systems employed for biodesalination are cell encapsulated gel beads, cellulose films, and most importantly microbial desalination cells. All techniques are discussed in detail in this paper. Overall, immobilized algae systems demonstrate strong potential for scalable and sustainable water treatment applications, particularly in decentralized or resource-limited settings. Future research should focus on developing systems and materials that ensure biocompatibility between algae cultures and their environment, be able to respond to fluctuating salinity, and hold their mechanical structures.