Microalgae-mediated heavy metal removal in wastewater treatment: Mechanisms, influencing factors, and novel techniques

In recent years, the proliferation of industrial effluents has posed significant challenges. In comparison to traditional physical and chemical methods, biological approaches have gained prominence among researchers due to their cost-effectiveness, abundant sources, ease of operation, and minimal secondary pollution. Moreover, employing microalgae for bioremediation offers the added advantage of concurrent production of diverse sustainable resources and biofuels. Nevertheless, challenges pertaining to recovery and reaction conditions continue to impede its large-scale implementation. Thus, exploration of improved solutions, such as enhanced reaction conditions, is imperative to maximize efficiency. In this review, we elucidate the mechanisms and pivotal factors involved in the removal of heavy metals by microalgae. Notably, we highlight innovative bioreactor technologies, including immobilization carriers, modified microalgae, and symbiotic systems, as focal points of this discussion. This comprehensive overview underscores the potential of microalgae-based bioremediation and paves the way for future advancements in this critical field.