Ammonia Nitrogen Removal in Mine Water using Electrocoagulation - A New Approach

2019

Tom Whitton, E2Metrix Inc.; Ihsen Ben Salah, E2Metrix Inc.; Mohamed Laaroussi, E2Metrix Inc.

Blasting activities can result in residual ammonia nitrogen in open pit or underground mine water.  Ammonia in water can be toxic to fish.   Moreover, mines in Canada are faced with new federal limits on toxic ammonia nitrogen discharge into waterways.  The new Metal and Diamond Mining Effluent Regulations limit the maximum monthly mean concentration of unionized ammonia at 0.50 mg/L (expressed as N), with a maximum peak concentration of 1 mg/L (N). Canada’s climate presents unique challenges to accommodating a traditional biological reactor for ammonia control, particularly for mines in development or those with limited infrastructure.  Besides water temperature control, no flow situation are common in Canada’s climate, creating difficulties in keeping the bacteria alive and the bioreactors functioning. In addressing these specific challenges, a new approach has been developed which uses electro-coagulation and a new patented electro-chemical approach - the production of struvite - to control ammonia nitrogen.  Sherbrooke-based E2Metrix, in collaboration with Golder & Associates, during the summer of 2017, installed and operated a pilot ECOTHOR™ system at a gold mine in development in northern Quebec.  The pilot unit successfully treated ammonia-laden mine water continuously on site, rendering it non-toxic and safe for discharge.    This presentation will highlight data and performance from this onsite piloting work, along with how this work has been leveraged for current and future ECOTHOR™ projects underway with a number of mines across Canada.

Keywords: mine water, ammonia, toxicity