A critical review on microalgae-driven wastewater treatment: Dual focus on high-value bioproducts recovery and...

Microalgae-based wastewater treatment is a sustainable approach to efficiently remove nutrients and heavy metals. Beyond these conventional pollutants, microalgae also exhibit potential for mitigating emerging contaminants (ECs) through adsorption, biodegradation, and biotransformation. Aside from the assessment of the environmental occurrence and ecological risks of ECs, this review highlights microalgal applications in diverse wastewater types and examines biosynthetic pathways for high-value compounds. Process control and optimization for biomass valorisation are discussed, focusing on the effects of light, temperature, nutrients, and cultivation modes on the synthesis of lipids, pigments, and polyunsaturated fatty acids. The potential applications of these bioproducts in bioenergy and medicinal applications are also addressed. However, exposure to ECs introduces challenges for biomass utilisation, particularly related to strain tolerance, bioaccumulation risks, and downstream processing. Key challenges for large-scale implementation-such as cultivation stability and economic feasibility-are outlined, with perspectives on advanced strategies including genetic engineering and intelligent process integration. The strategic significance of this green technology in supporting a circular economy and achieving carbon neutrality is emphasised.