NITREM Extended is a system solution specially developed for businesses within the mining industry and for landowners. 

NITREM Extended delivers a unique and almost maintenance-free solution for nitrate reduction in leachate combined with a sustainable landscape design for rock piles. NITREM Extended reduces the amount of nitrate in rock pile leachate combined with landscape design that enhances biological diversity and provides an opportunity to return to traditional land use after the end of operations.

NITREM Extended consists of two components: a bioreactor and a method for geomorphological landscape design. 

The bioreactor is an oblong pit covered with a water-tight geomembrane and filled with pine woodchips. The leachate that leaves the rock pile flows through a water collection system and is directed toward one of the short sides of the bioreactor. The water flows through the pine woodchips where denitrification occurs and denitrifying microorganisms convert the nitrate in the water to harmless nitrogen gas.  

The large amount of organic matter available in the bioreactor serves as a carbon and energy source for microorganisms. The water that leaves the bioreactor has a greatly reduced nitrate concentration. 

To optimize the function of the bioreactor, the flow rate and water quality needs to be monitored. With NITREM Extended, monitoring is included. NITREM’s landscape design focuses on the construction of the waste rock pile from mining operations. The rock pile is designed using geomorphic principles to ensure long-term stability and minimal erosion. Geomorphic design also creates a more natural landform to help blend in with the surrounding natural environment and allows for better hydrological control for the collection of leachate. The leachate is then directed into the bioreactor and treated for removal of nitrate. This kind of landscape design not only promotes the reduction of nitrate concentrations, but also increases functionality, local biodiversity, and provides an opportunity for the rehabilitation of the land after the mining operations have ended.

Illustration showing how water flows from the rock pile to the water collection system and through to a bioreactor where the nitrate content is reduced, before the water is passed on to a recipient. 

The following is included in NITREM Extended:

  • Identification of the customer’s specific needs with a water collection system and bioreactor, including measurement of flow and nitrogen levels and a general hydrogeological investigation (Desktop analysis).
  • Cost estimate for design and construction of water collection system and bioreactor.
  • Delivery of drawings for water collection system and bioreactor based on existing measurements.
  • Telephone support during construction as well as during the first year of operation.
  • Help with procurement of contractor.
  • Sampling and system monitoring.
  • Desktop landscape analysis that includes review of available aerial images, topography surveys, GIS review of the relevant area including reference sites, review of current rock pile processes from available reports, review of recovery plan from available reports and analysis of the type of data that will be required in the next step of the project.

El Machorro – Reclaimed mine after the end of mining operations.

Start date – 2012 
Area
 – Total of 1 ha (demonstration project). 
Construction time – two weeks in September 2012 and two weeks in 2014. 
Cost – Cost are determined on a project to project basis as local conditions and contractor cost differ vastly. International construction experience has shown that geomorphic designs constructed from the beginning of a waste rock pile cost approximately the same as a conventional design
Location – Poveda de la Sierra (The Guadalajara Province, Castille-La Mancha, Spain).
Mine type – Kaolin, rock mine.

Source: www.restauraciongeomorfologica.es

Download more information about NITREM Extended here.