Bioremediation of cyanide in tailings wastewater – a mini review

Abstract

Cyanide-containing compounds are widespread in industrial wastewater from the mining and metallurgical industries. In aquatic environments, cyanide occurs predominantly as free cyanide (CN^-) and hydrogen cyanide (HCN), both of which are highly toxic due to their inhibition of cellular respiration. This mini-review provides a comparative analysis of the main physicochemical and biotechnological methods for cyanide removal from tailings wastewater, emphasizing the factors governing process performance and the constraints on industrial implementation. Based on a critical assessment of recent studies, chemical neutralization and oxidation technologies, as well as microbial cyanide biodegradation pathways, are discussed. The review shows that physicochemical methods can reliably reduce toxicity; however, they often require substantial reagent and energy inputs and may generate harsh reagents. Biological approaches using microorganisms and enzymatic systems can transform cyanide into less hazardous compounds, reducing the need for aggressive reagents and minimizing by-product formation. Although biological systems are generally slower than chemical oxidation, advances in strain development, process monitoring, and bioreactor technologies are enhancing the feasibility of biological and hybrid treatment trains for the sustainable treatment of tailings effluents.