| name: | Dr Paul Connett |
| section: | Recycling and Waste |
| for: | The Defence |
| experience: | PhD chemist specialised in research into waste management |
summary:
In my view, the only chance one would have of getting "controlled combustion" with the burning of polysterene packaging in a commercial incinerator would be if the incinerator was designed and built only to burn polysterene packaging, and all other trash was handled elsewhere. The moment other materials are introduced - even paper - the chances of maintaining a controlled burn to laboratory standards are highly unlikely.
cv:
Professor of Chemistry, St Lawrence Univeristy
9.5 years in research into waste management
Full cv:
(not available for this witness)
full statement:
As a PhD chemist I have specialised over the past 9.5 years in research into waste management with a particular interest in the dangers posed by municipal waste (ie trash) incinerators. I have attached my curriculum vitae to illustrate how extensive my involvement has been in these areas.
I find it difficult to believe that any credible expert could maintinan that a "controlled burn" could be maintained in a trash incinerator akin to the "controlled burn" possible in a laboratory experiment. There are many variables with a typical municipal wastestream entering an incinerator which would defy the "total control" over the burning process. Indeed, when Swedish researchers were trying to find a way of predicting dioxin emissions form a trash incinerator they has to introduce about 20 variables before their computer model could match dioxin emissions with dioxin projections. (These findings were presented a the Sixth International Symposium on Cholrinated Dioxins and Related Compounds, which I attended in Fukouka, Japan in 1986). Moreover, these variables related to operating parameters like temperature and carbon monoxide levels and didn't deal with the most difficult variable of all, namely the composition of the trash itself. Trash is a heterogeneous mixture which can vary from day to day, even minute to minute, with respect to moisture content, plastic content, heating value, heavy metal content and so on, all of which can effect the minutia of combustion.
The one thing that has become very clear to me is that incineration - even of simple mixtures of substances - is a very complex matter indeed. For example, in 1984 Dr Barry Commoner was widely ridiculed in the US for suggesting that doxins could be regenerated in a trash incinerator after the gases had left the combustion chamber (ie somewhere between the furnace and the stack), however this view was vindicated in 1985 when experiments in Germany, and measurements at an incinerator in Canada, indicated that dioxins were being formed on the fly ash in the air pollution control equipment - ie the cooler parts of the system. Now, in 1994, the same engineers that ridiculed Commoner in 1984 are advocating contol strategies which quench the gases leaving the combustion chamber before they enter the air pollution control devices, to avoid the "post combustion formation" of dioxin. Even with this strategy it is proving necessary to introduce activated charcoal into the system in order to meet the German standards for dioxins and mercury. At this moment there are few, if any, incinerators in the UK that can meet German standards. It has been clear from the British experience with incineration that its existing incinerators have put large quantities of dioxin into the environment and many of them will either be closed down or significantly retrofitted. Clearly, the term "controlled combustion" is a relative term: it is relative to time - are we talking about "controlled combustion" in the 1970's, 1980's or the 1990's? Or are we talking about "controlled combustion" in Germany or the UK?
Because neither heavy metals like lead, cadmium, mercury or chromium, nor non-metals like chlorine, can be destroyed in incinerators, because they are elements, then "controlled combustion" alone cannot assure protection of the environment. Even the best combustion systems have to be backed up with expensive and complicated air pollution control devices. However, the smaller the particles, the more difficult they are to remove. This is significant because it is the smaller particles which present the larger surface area for condensation. Moreover, the effectiveness of these control devices is highly dependent on conscientious and expensive maintenance, which sadly, when these incinerators are operated for profit, does not always occur. To give one example from the US, a modern "state-of-the-art" trrash incinerator which was built in Indianapolis, Indiana, and was fitted with a dry lime scrubbing system followed by a fabric filter, has had over 6000 exceedances of its air permit pollutant levels in the two years since it went on-line in late 1988! Among other things it appears that the operators were not using the maintenance budget for the purpose for which it was intended. Thus one cannot talk blithely about "controlled combustion" without recognising the difference between the "theory" of incineration, as frequently observed in the real world.
To further illustrate the formidable problems involved with controlling the burn of a mixture of polysterene and other substances in the municipal waste stream, I would cite the experiment in which researchers burned both polyethylene and poly vinyl chloride in controlled laboratory experiments. In both cases they were able to find a set of conditions in which the polyethylene was converted to carbon dioxide and water, with practically no evidence of products of incomplete combustion appearing in the gas chromotograph, and the poly vinyl chloride was converted to carbon dioxide, water and hydrogen chloride, again without any evidence of byproducts. However, when they burned the two plastics together - under either set of conditions - they found an enormous number of byproducts. They reasoned that the polyethlylene, which burns easily, sucked the oxygen away from the polyvinyl chloride, allowing the later to pyrolyse producing the products of incomplete combustion. If this was the case IN THE LAB with just TWO PLASTICS, consider the far greater difficulty when polysterene is burned with A MULTITUDE OF OTHER MATERIALS in a COMMERCIAL INCINERATOR!
In my view, the only chance one would have of getting "controlled combustion" with the burning of polysterene packaging in a commercial incinerator would be if the incinerator was designed and built only to burn polysterene packaging, and all other trash was handled elsewhere. The moment other materials are introduced - even paper - the chances of maintaining a controlled burn to laboratory standards are highly unlikely.
| date signed: | 10th July 1994 |
| status: | Statement read out in court |
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