Project objectives:
The aim of the PIRAMID project was to achieve the following:
- Completion of a database of existing passive in-situ remediation (PIR) systems for acidic / ferruginous mine waters in Europe
- Develop process-based models of PIR systems
- Evaluate PIR applicability for countries in central and eastern Europe which were lacking the technology in 1999.
- Experimentally evaluate, in the field and the lab, novel reactive substrates for PIR systems
- To produce and disseminate engineering guidelines for the future design, construction and operation of PIR systems.
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Project
Summary:
Acidic drainage from old mines and associated sites is a major cause of ground and surface water pollution in the EU, which can persist for centuries after mine
abandonment. Consequently there is a need for cheap, sustainable remedial methods, such as passive in situ remediation (PIR) technologies. PIRAMID will
draw together previously separate (but conceptually identical) developments in the creation of (i) artificial wetlands and (ii) subsurfacereactive barriers
for PIR of acidic, metalliferous drainage , into a singme database. This database will support the development of process-based models of PIR system performance,
which can be used to improve design criteria. Experimental studies of alternative PIR media will also be made and the results incorporated into engineering
guidlelines for the wider application of PIR in Europe. Suitable EU areas for PIR will be identified and hydrogeochemically evaluated.
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Achieved Objectives:
The scientific research completed as part of the PIRAMID project has produced an abundance of information which provide many possibilities for the application
of passive in-situ remediation to a wide range of pollution problems. In particular:
- the critical importance of macrophytes in achieving low residual Fe concentrations in aerobic wetland systems was demonstrated, together with fundamental
insights into the effects of elevated proton and metal activities on wetland plant growth
- low-cost substrates for treatment of acidic waters have been investigated (including synthetic zeolites made from PFA, caustic magnesia, and organic
matter promoting dissimilatory bacterial sulphate reduction, in particular green waste composts and farmyard manures)
- the use of oxidative and reductive systems for the treatment of arsenic-rich mine drainage has been investigated, with the kinetics of oxidative systems
proving the more favourable of the two; arsenic-oxidising bacteria have been identified and isolated
- the safe, passive destruction of residual cyanide leaching from gold mine tailings has been achieved using compost-based wetland-type passive systems
(which also remove residual copper), thus complementing active cyanide-destruction techniques used while the mine remains operational.
- detailed field investigations of: (i) conventional wetland-type passive systems in the UK, France and Slovenia, removing Fe, As and U respectively from
diverse mine waters (ii) a conventional permeable reactive barrier (PRB) within an aquifer at Aznalcóllar (Spain), treating highly acidic groundwaters
associated with a base metal mine, and (iii) a novel, hybrid passive system at Shilbottle (UK) which intercepts extremely acidic colliery spoil leachates
using a surficial PRB (with substrates including organic matter mixed with limestone and / or blast furnace slag, promoting inorganic and bacterial neutralisation
processes), which releases its effluent into a series of oxidation ponds and aerobic wetlands downstream.
Significant advances were also made in relation to natural and stimulated natural attenuation of acidity in mine pit lakes, and in the assessment of the sustainability
of dry covers and water covers for tailings and waste rock piles, under both cold (sub-arctic) and warm (Mediterranean) climatic conditions.
Modelling software has been developed allowing simulation of subsurface-flow passive treatment systems(RETRASO), wetland-type systems (NOAH2D) and
the natural attenuation of mine water pollutants in flooded deep mines (RUMT3D).
PIR was found to have considerable potential for application in many European countries, and offers potential solutions to pollution problems in most Newly-Associated
States with significant past or present mining industries. Such developments, in these and other countries, will be greatly facilitated by the PIRAMID engineering
guidelines.
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Product Descriptions:
Acidic mine drainage and similar wastewaters (such as leachates from acid-sulphate soils) are a major cause of ground and surface water pollution in the European
Union. Because such pollution can persist for decades and even centuries after the cessation of industrial activity, there is a pressing need to develop cheap,
sustainable remedial methods. PIRAMID has sought to harmonise research and practice efforts in Europe to create passive in situ remediation (PIR) methods
for acidic drainage treatment.
The public availabe products are:
- The final report of the project (Generic)
- Engineering guidelines for the passive remediation of acidic and/or Metalliferous Mine Drainage and similar wastewaters (Generic)
They can be downloaded from the project website.
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Prof Paul Bardos