Management of Nitrogen Compounds in Mine Wastewater

TECHNICAL SUMMARY

Nitrogen compounds in mine wastewater originate primarily from anthropogenic sources such as blasting agents and cyanide use in metallurgical processes. These compounds, including ammonia, nitrate, and thiocyanate, present challenges for environmental compliance, particularly as regulatory standards become more stringent and extend beyond water quality to include toxicity and ecological impact. :contentReference[oaicite:0]{index=0}

Traditional nitrogen management approaches rely heavily on biological treatment systems. While effective in some applications, these systems are complex, sensitive to operating conditions, and can generate by-products that contribute to effluent toxicity. They also require large footprints, long start-up periods, and careful control of environmental variables such as temperature and nutrient balance. :contentReference[oaicite:1]{index=1}

This paper evaluates non-biological alternatives, focusing on a combined process of selective ion exchange and electro-oxidation for the removal of thiocyanate, one of the most recalcitrant nitrogen compounds in mine water. The process selectively captures thiocyanate using ion exchange resin, followed by electro-oxidation to convert it into cyanide for potential reuse or further treatment.

Bench-scale testing demonstrated that thiocyanate concentrations could be reduced to below 5 mg/L, while concentrating the compound for efficient downstream processing. Electro-oxidation achieved approximately 80% current efficiency, with recovery of a significant portion of nitrogen in reusable form. :contentReference[oaicite:2]{index=2}

The paper also introduces a holistic framework for nitrogen management based on Risk Adjusted Life Cycle Cost (RALCC), highlighting the importance of considering long-term operational risks, regulatory compliance, and potential value recovery when selecting treatment strategies.