Sustainable acid mine drainage treatment: A comprehensive review of passive, combined, and emerging technologies

Acid mine drainage (AMD) has always been a global environmental issue; particularly in countries with intensive mining activities dueto the severity of its ecological, human health, and socio-economic effects. AMD is generated by both active and abandoned mines (particularly gold and coal) in countries with advanced and intensive mining industries. As such, research are still ongoing to prevent its formation. On the other hand, the already generated AMD is mostly treated using active and passive approaches, with the first being driven by chemical and energy inputs while the second is self-renewable approach but efficient to be used as a polishing step. The drawbacks associated with active and passive treatment methods have motivated the design and exploration of hybrid, integrated, and emerging technologies. Hybrid and integrated systems are promising and cleaner technologies since they can effectively treat AMD to required standards while recovering minerals and reclaiming water thereby ensuring zero liquid discharge (ZLD). Emerging technologies are cost-effective, however, they are slow and not eco-friendly in the case of nanoremediation. Herein, the body of knowledge on AMD treatment technologies is comprehensively reviewed and discussed, with a focus on their sustainability using life cycle assessment methodology (LCAM).