Phycoremediation of Potentially Toxic Elements for Agricultural and Industrial Wastewater Treatment: Recent Advances, Challenges, and Future Prospects

Phycoremediation is an eco-friendly and low operational-cost technique. It promotes green technology for biofuel production, high nutrient recovery, and wastewater treatment through microalgae. This review encompasses a set of algal-based remediation methods for potentially toxic elements (PTEs) from agricultural discharges and industrial wastewater. Large-scale algae production approaches, such as suspended cultures in open ponds or closed reactors and immobilized cultures, include biofilm and matrix-immobilized systems for biomass and the removal of wastewater nutrients, as well as PTEs. Fundamentals for remediation of PTEs using microalgae are biosorption and bioaccumulation, and thus, this review summarizes how microalgae are beneficial for wastewater treatment. Further, this review describes recent technologies, i.e., bioreactors, high-rate algal ponds, commercial sorption, etc., used in wastewater treatment and their specifications and eco-friendly remediation of contaminants from agricultural and industrial effluent. Wastewater treatment process utilizes algae or macro-algae in both conventional facultative ponds and advanced algal ponds, such as high-rate algal ponds with photo-bioreactors. This review also covers the advancement in the bioremediation of nutrients and PTE contaminants in agricultural and industrial wastewater using microalgae. Lastly, this review concluded with various limitations, challenges, and prospects on algae implications in wastewater, considering carbon neutrality and circular economy.