Microalgal-based desalination brine remediation: Achievements, challenges, and future research trends

Desalination brine discharge has several negative impacts on the marine environment, such as increase in salinity levels, effects on marine biodiversity, and alteration of the physical and chemical characteristics of water. In addition, desalination plants consume significant amounts of energy, which contribute to carbon emissions and global warming. Various brine management strategies have been adopted to mitigate the negative impacts of brine discharge, these are often expensive, require extensive infrastructure, and may not be feasible in all locations. The focus of this review is Algae-based brine bioremediation, which is a promising approach to managing brine discharge, as it not only reduces the environmental pollution impacts of brine discharge but also produces valuable biomass products. Mechanisms employed by microalgae for brine bioremediation, including nutrient recovery, organic and heavy metal removal through processes like biosorption, bioaccumulation, and metal detoxification are discussed. Algae can grow in high salinity water and use the nutrients present in brine to produce biomass, which can be harvested and used for a variety of applications, including biofuels, feed, and pharmaceuticals. This approach can potentially provide a sustainable and cost-effective solution to managing brine discharge from desalination plants. The review highlights achievements in microalgae-based brine remediation, including nutrient sequestration and the valorization of microalgal biomass after treatment. Challenges in this field, including brine's high salinity and algal biomass harvesting, are addressed. The paper also outlines research trends that encompass strain selection and optimization, carbon capture, nutrient recycling, photobioreactor design, anaerobic digestion, biochar production, and techno-economic feasibility analysis. These future-focused approaches aim to enhance the sustainability and efficacy of microalgal biomass cultivation in brine remediation.