Introduction

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WRc has led a consortium of European partners in a successful bid to the European Commission DG XII Environment and Climate Programme for financial support of a project to develop a method for remediating heavy metal contaminated land using biomass fuel crops.. The EC has agreed to provide 50% funding, which is usual for successful bids, and balancing funds for UK participants now being sought in the UK. Participation in EU supported projects through part-funding is a highly cost effective way into research and development. Co-funding organisations will have access to the outputs of the entire project at a cost of less than 2% of the total project value. The project is approved under the Landfill Tax Credit Scheme, hence collaborators registered under this Scheme can reclaim 90% of their contribution to the project against landfill tax returns.

This document outlines the programme of work, outputs, costs, benefits and other information about the project. The participating countries in addition to the UK are Germany, Spain, Sweden and Austria.

Resumé

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Land on the urban fringe can be contaminated with heavy metals as a result of industrial activity, posing a risk both to human health and to the environment, and restricting the use to which that land can be put and hence its value. Remediation may be possible by chemical means, or by burial of the contaminated area, but this is expensive and is seldom undertaken for large areas suffering from low level contamination. Such land can place a blight on the development potential of a locality, discouraging inward investment and economic redevelopment of regions of industrial decline.

A number of plant species grown as biomass fuel crops have been found to take up heavy metals, frequently in unusually high concentrations. This project proposes to use this trait to remove heavy metals from contaminated land, a process referred to as bioremediation. There are several advantages to the use of biomass fuel crops over other approaches to bioremediation: high productivity and the production of large quantities of biomass; equipment exists whereby the crops can be managed by standard agricultural techniques; an economic return can be obtained from the land;

Expansion of the adoption of biomass fuels is being limited by competition with other more profitable uses of agricultural land. Industrially degraded land is frequently of low value and under-utilised; fuel production on these sites represents an opportunity to remediate or stabilise contaminants, gain economic return from the land, stimulate employment and accelerate the market penetration of biomass fuels.

The characteristic whereby biomass fuel crops take up and tolerate, to a greater or lesser degree, heavy metals into their harvestable parts can be employed in one of two possible strategies (a) site stabilisation and (b) site de-contamination.

Site stabilisation: biomass crops which do not take up metals into their harvestable portion but which can tolerate metalliferous growing conditions can be used to physically and chemically stabilise contaminated land, without affecting the extent of contamination.

Site decontamination: varieties which take up metals into their harvestable parts can be used to remove metals from soil. The use of this biomass as a fuel justifys the long time-scales required to affect full renovation, and permit recovery of the metals in a specially developed flue gas cleaning system.

The biomass fuel crop species to be investigated are Salix, Miscanthus, Phalaris and Eucalyptus.

The proposed project addresses demands for sustainable environmental technologies in that it provides a closed loop system for contaminated land remediation, reuse of the metals recovered and recycling of the principal by-product of the technology, namely biomass ash, as a fertiliser and liming agent. The decision support tool (DST) developed within the project, for the planning and execution of bioremediation by the proposed technology will promote the adoption of the best available technology for any specific site. Inclusion of Life Cycle Analysis (LCA) and Environmental Impact Assessment (EIA) stages in the DST will ensure that solutions can be developed for a site which will lead to overall environmental benefit.

Outputs

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A large number of technical outputs will result from the proposed project. A selection of these are listed below. In addition, a number of tools will be developed for use by planners and developers of degraded and contaminated land.

Tools:

• a computer based decision support tool and associated data bases for the assessment of the options for site bioremediation;
• a method of LCA specifically for assessing the suitability of contaminated sites for bioremediation;
• a protocol for the EIA of projects to bioremediate heavy metal contaminated sites;
• expanded computer expert system for assessing environmental hazard associated with chemical spillage to include a soil simulation model and associated data base.

• soil chemistry manipulation techniques to manage the environmental availability of heavy metals;
• chemical characterisation of a wide range of metal contaminated soils;
• comparison of techniques for characterising metal associations in soils;
• characterisation of heavy metal uptake by several hundred fuel crop varieties;
• rapid screening techniques for heavy metal tolerance by plants;
• characterisation of the factors controlling fractionation of heavy metals in combustion systems;
• evaluation of the suitability of commercially available waste incineration metal recovery systems for metal rich biomass fuels;
• evaluation of the environmental performance of a range of contaminated land remediation techniques, with regard to their sustainability and overall environmental impact.

Project tasks

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1. Screening of woody and graminaceous biomass fuel crops for heavy metal uptake:

• development of a rapid screening test that reflects the long term response of fuel crops to metalliferous growing media;
• screening of over 200 varieties of Salix, 20 Miscanthus and 20 Phalaris clones for metal uptake characteristics;
• testing of Eucalyptus tolerance of mercury.

2. Manipulation of soil conditions to control - enhance or limit - metal availability

In most contaminated soils the proportion of the total metal content which is bioavailable, and hence environmentally active, is small, typically less than 5%. However, soil quality standards for evaluation of contaminated land are based on maximum permissible concentrations of total metals. To maximise the potential for metal removal by crops, it is necessary to increase the size of the labile pool by releasing metals from the more resistant chemical forms in the soil. This study will focus on the relationship between labile and insoluble heavy metal pools in soil and what measures can be taken to actively manage the form in which a metal is present in order to manipulate, either enhancing or reducing, the plant uptake of the metal. Activities will be both laboratory and field based.

3. Recovery of metals during fuel conversion

The take up of metals into fuel crops will give rise to metalliferous fuels which potentially may pose problems for emission standards and flue gas cleaning in conversion facilities. Techniques are being developed based on combustion chamber design and flue gas cooling systems to capture and concentrate the metals in the fly ash fraction. These will be further refined in this project to permit the beneficial recycling of the bottom ash and the recovery of the metals in the flue ash for reuse.

4. LCA and EIA of contaminated land remediation strategies

There is considerable potential for actions taken to remediate contaminated land to result solely in the transfer of the contamination to an alternative location or from one environmental compartment to another, with no reduction in the significance of the contamination. A series of LCAs are to be conducted of a range of clean up strategies to ascertain the relative environmental impact of each and identify how these may be minimised. LCA and EIA methodologies are to be developed specifically for use in contaminated land remediation developments.

5. Development of a decision support model

A computer based tool will be developed whereby the suitability of a specific site for remediation by fuel and fibre crops can be assessed. This will take account of the site physical, chemical and biological characteristics, location, the level of risk to health and the environment it represents and the potential economic value of the site. Such a tool would be of use to local government planners, industry and developers when assessing whether and how to remediate specific sites.

The project aims to improve the methodological toolbox for the registration and risk assessment of sites through the adoption of LCA and EIA techniques, while at the same time developing a computer based decision support tool for use by those involved in land remediation planning and implementation.

Benefits of EU collaboration

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Participation in EU supported projects is a highly cost effective way of financing research. For less than 2 % of the total project value co-funding organisations will have access to the results of the entire project.

International partners in this project have expertise not currently available in the UK hence, co-funders will be able to benefit from a technical resource not otherwise easily accessible.

The project adopts a systems approach to ensure that no environmental compartment is negatively impacted by the proposed bioremediation technology. The proposed team is highly multi-disciplinary and contains both industrial and research partners. Hence it is well placed to promote the exploitation of the technology.

Partners

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Participating countries in addition to the UK are Germany, Spain, Sweden and Austria. Partner organisations are:

1. Soil, Waste and Groundwater Group, WRc;
2. University of Glasgow Department of Environmental Chemistry.
3. Svalof Weibull - Swedish plant breeding company;
4. University of Technology, Graz Institute of Chemical Engineering, Austria;
5. Centre for the Development of Renewable Energy, Madrid, Spain;
6. Institute for Energy and Environmental Research, Heidelberg, Germany;
7. University of Hohenheim Institute of Soil Science Department of Soil Chemistry, Germany.

Cost

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The total value of the bid to the EU is 1.544 M over three years. WRc is currently seeking £75 000 per annum for 3 years to balance the EU contribution to UK participants. This may be derived from a single source or through several collaborators.

A group of four collaborators would each contribute £18 750 annually and five collaborators would contribute £15 000 annually. Partial funding has been agreed by the Environment Agency. Additional collaborators are sought.

Contact for further information

, Waste and Groundwater Group, WRc plc, Medmenham, Henley Road, Marlow, Buckinghamshire SL7 2HD. Tel: (01491) 571 531, Fax: [01491 579 094]