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Controlling dioxin pollution

   
 
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Incineration Fly ash creates dioxin pollution.

A group of laboratories came together to improve the trace analysis of certain dioxins and furans, which are organic environmental pollutants emitted by waste incinerators.
Through collaboration, a certified reference material was produced to validate the methods used to measure the levels of contamination in fly ash. This ensures that, across Europe, measurements are accurate and reliable. The reference material is now available to any organisation monitoring dioxins.

 

Dioxins and furans are chemicals that contaminate the environment. They have been known to cause painful skin disorders and some evidence suggests they induce still births, deformities and cancer in extreme cases.

To make matters worse, they are extremely stable and do not easily get broken down in natural environments. This, coupled with their high solubility in fats and oils, causes them to accumulate in living organisms and in soils and sediments. The chemicals are passed through the food chain and they are harmful to humans and animals. It is agreed that they should be handled with extreme care due to their toxicitiy.

The chemicals are not produced by man intentionally. They are often by-products of chemical reactions in the industrial production of chlorinated disinfectants, pesticides and herbicides, as well as being produced in the pulp bleaching in paper manufacture and by petrol cars. The main sources of dioxins are steel works and waste incineration.

Dioxins damage the environmentA number of accidents have released dioxins into the environment. This includes the Seveso explosion in Italy in 1976, which increased scientific, social and political interest in these harmful chemicals. Much work has been done to identify sources of dioxins, assess their damaging effects and measure levels in many different environments.

Many of the industrial processes producing dioxins have now either been banned or are strictly regulated. The threat of dioxin emission from these sources is relatively low. Incineration processes, however, remain a major source of dioxins.

World-wide legislative and technical efforts are aiming to reduce dioxin emissions from municipal or dangerous waste incineration. Through a Directive, the European Commission established a limit value for the emissions from hazardous waste incineration plants. Many countries also set this limit value to municipal waste incineration. As a result, the evaluation and monitoring of both new and existing incinerator emissions has become a major concern. Some of the dioxins and furans are found in incineration fly ash, which is the finely divided particles of ash found in the flue gases arising from the combustion of waste.

Until the early 1990s, the reliability of dioxin measurements performed was highly questionable. One reason for this was the fact that there was no reference material that laboratories could use to check the accuracy of their analytical methods. For accurate quantitative measurements of the different members of the dioxin and furan families, a full validation of the highly complex analytical methods was necessary.

Perfecting measurement methods

These methods require the chemist to extract the dioxins into a solution in order to measure their concentration. The efficiency of this process was questionable and it is easy to see that if only half the total dioxins are extracted into solution, the reading obtained for the dioxin level in the ash will be less than the true value. If a reference material could be made available to the laboratories, the techniques used to make measurements could be verified as being accurate and reliable.

This prompted a project to develop a fly ash material that has known levels of the twelve most toxic dioxins and furans.

A sample of fly ash was collected and prepared in a way that ensured that the particle size was sufficiently small and constant throughout the material. This is important as the particle size and hence surface area of the particles can have an effect on the amount of dioxins that can be extracted into solution for measurement.

Building on previous work

An earlier project proved the material's suitability for use as a Certified Reference Material that must have a constant chemical composition over several years and must be able to be sent to users via travelling conditions which may be involve high temperatures or low pressures. Seventeen expert European laboratories from nine different countries used their skills to assess various measurement techniques. The group decided to use gas chromatography with mass spectrometric detection for the final measurement of each of the twelve chemicals.

Each institution improved and optimised its own sample preparation procedure and the use of its own instruments, which varied from laboratory to laboratory. Many meetings and workshops provided a forum to discuss the results and critically examine the data and procedures.

The material is unique in the field of dioxin determination. World-wide, environmental analysts rely on this material in order to check the accuracy of their methods and for quality control of the measurement of dioxin and furan levels in fly ash emissions. In parallel, another project has produced a certified reference material for the dioxins and furans in milk powder that is intended for use by food control laboratories. Another project has begun to produce a fly ash material with much lower dioxin levels as well as calibration solutions for emission measurements.

 

 

Project Title:  Certification of PCDD and PCDF in Fly Ash

Programmes: Standards, Measurements and Testing
Contract Reference:  

Cordis DatabaseFor more information on this project,
go to the Cordis Database Record

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