Selective recovery for enabling passive Treatment of Alkaline Leachate (SREPTAL)

This project aims to provide a novel treatment train that integrates selective metal(loid) recovery from alkaline waters with effective long-term remediation of high pH drainage.

This provides a new approach to addressing the enduring liabilities associated with alkaline drainage from a range of high temperature residues such as bauxite processing residue, and builds on our promising pilot findings for selective metal(loid) recovery and treatment of Bauxite Residue Disposal Area (BRDA) leachates using wetlands.

We will meet this overarching aim by addressing the following four objectives which map onto discrete workpackages: Evaluate performance of ion exchange resins for selective recovery of problematic pollutants and critical metal(loid)s, optimise resin deployment configuration for system longevity, evaluate buffering rates of residual leachates in constructed wetland cells, undertake full life cycle and techno-economic assessment to evaluate economic and environmental footprint against conventional treatment options.

The technology we are proposing is modular with a range of TRL across the different components. Overall, we assign a TRL of 3 based on the elements least developed (selective recovery) which are a key focus here. The removal of contaminants and critical raw materials (e.g. vanadium, gallium) allows for value recovery from leachates and enables application of passive treatment technologies, which could otherwise be unsuitable for deployment where concentrated metal(loid)s may transfer to food chains. This solution provides benefits for value recovery, regulatory compliance, environmental improvement, and lowered long-term treatment costs (and embedded carbon) by adopting passive approaches.