General Cleanup Technology

Sustainable approaches to water treatment and the reclamation of mining areas

In the current project, the partners developed and tested sustainable approaches for the reclamation and water treatment of mining areas using plant-based methods in the north eastern Vietnamese province of Quang Ninh. In the long run, these concepts are designed to help reduce the carbon-based environmental pollution in Southeast Asia. This includes compliance with surface water value limits and the protection of the natural biodiversity in regions affected by mining.

 

Summary

Coal mining in the Vietnamese province of Quang Ninh affected both local residents and the environment by introducing contaminants into the water, soil and air, while also causing erosion, land use competition and a loss of natural vegetation. The Vietnam National Coal-Mineral Industries Group is mandated by the state to reduce the environmental impact and to reclaim abandoned mine sites, revitalising them for subsequent use. To this end, UFZ and BioPlanta developed sustainable approaches for the re-cultivation and plant-based wastewater treatment of two mine sites in Quang Ninh. These plans included:

  • the selection of potentially suitable plant species native to Vietnam, which would grow naturally on the mine sites;
  • the investigation of these species in terms of their actual suitability for re-cultivation, using (i) test plantings, (ii) measurement of growth and adaptability, (iii) behavioural testing for germination, inter and intra-species competition, water scarcity tolerance and leaf litter degradation;
  • the study of natural soil aggregates for improved soil development;
  • the determination of pollutant loads in leachate and sump water and the optimisation of complex degradation processes in constructed wetlands with respect to such pollutant loads;
  • the establishment of a constructed wetlands pilot plant for the decontamination of water at the mining site.

 

Results:

  • The vegetation naturally occurring in mine tips include plant types suitable for re-cultivation.
  • Sifting the waste material improves plant growth: fine porous material increases the water holding capacity and is best for root growth, while it also promotes oxidative processes and raises the pH value. Charred rice straw used as a soil additive also increases the pH value and improves the supply of nutrients to the plants.
  • The use of locally appropriate, native vegetation ensures an on-going supply of nutrients and humus formation while reducing the risk of mine fires through a faster biomass turnover.
  • The mine wastewater has high heavy metal loads and sometimes high sulphate loads, as well as low pH values.
  • The constructed wetland pilot plant was built from a combination of limestone drainage with a compost component and an adjacent horizontal permeable gravel filter for planting.
  • The pH value was neutralised in the pilot plant; concentrations of manganese fell below the statutory limit of 1 mg/L.

More Project Informations

Project titel : Verbundprojekt Bergbau und Umwelt Vietnam / Unterverbund Pflanzenbasierte Methoden zur nachhaltigen Haldenrekultivierung und Behandlung von Bergbauwässern

Project number: 02WB0957 - 02WB0958

Project period: 2008 - 2011

Project region: Vietnam

Project contact:

Herr Dipl.-Ing. Kuhne

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Frau Dr. Knapp

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Herr Dr. Klotz

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Quelle: Federal Ministry of Education and Research (BMBF)