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Incinerators remain net dioxin sources
The UK incineration lobby, with Professor 'Pyro' Porteous leading the way
and supported by Gev Edulgee of ERM, have been claiming that MSW
incinerators are dioxin sinks. This was never really a sustainable
argument and even ETSU have now decided that they should distance
themselves from it. You may find the report below useful. I am slightly
surprised by the findings of the study that UK MSW contains 3-13ng/TEQ
dioxin (above 'background' soil contamination levels) whilst incinerator
bottom ash is claimed to contain 7.5 - 28 ng/kg. Any other data on levels
of dioxin in modern incinerator residues would be very useful. When I
went round SELCHP (a 'state of the art' UK incinerator with Maddy Cobbing
from Greenpeace and Ralph Ryder of Communities Against Toxics they
refused to provide us with a bottom ash sample and seemed very touchy
about providing any data.
ENDS Report 273 October 1997
Incinerators remain net dioxin sources, says ETSU
The new generation of municipal waste incinerators produce 15 times as
much dioxin as they destroy, according to the Energy Technology Support
Unit (ETSU). The finding contradicts claims by the Energy from Waste
Association (EWA) that modern plants act as d toxin sinks.
Dioxin releases to air from municipal incinerators have fallen
considerably as a result of new emission limits introduced at the end of
1996. As a result, the EWA has claimed, modern, well-managed plants now
"act as net destroyers of dioxin. "
The Association's claim is based on dioxin balances published by the
International Ash Working Group (IAWG) which suggested that a modern
German incinerator destroys more than 78% of the dioxins present in the
Dioxin measurements in household waste and incinerator residues, carried
out for the Environment Agency by AEA Technology, paint a different
picture.' In the latest issue of waste journal 117armer Bulletin, Stephen
Burnley, a senior consultant with ETSU, part of AEA, uses these data to
calculate dioxin balances for a modern UK incinerator fitted with a
semi-dry scrubber and bag filter.
According to his best estimate, a modern incinerator produces about 15
times as much dioxin as that in the incoming wastes (see table). Using
pessimistic assumptions, the overall dioxin loading could be increased
170-fold. And even on optimistic assumptions, the incinerator remains a
net dioxin source.
Dioxin balance for a 100,000tpy incinerator, gTEQ/y
Optimistic Pessimistic Neutral
Input waste 2.1 0.05 0.41
Bottom ash 0.22 0.83 0.62
control residues 3.1 6.9 5.2
Flue gas 0.025 0.61 0.25
Total output 3.35 8.34 6.07
Net dioxins 1.25 8.29 5.66
The main reason that Dr Burnley came to a different conclusion from IAWG
is that dioxin levels in UK household wastes were found to be relatively
low - possibly reflecting a reduction in environmental levels of dioxins.
Earlier overseas reports put dioxins levels in whole waste at
Waste from Woking, Glasgow and Colwyn Bay generally showed fairly
consistent dioxin concentrations of 313ngTEQ/kg, although Dr Burnley used
the full data spread of 0.5-21ngTEQ/kg. Only small differences between
the waste fractions were found, apart from fines in the Colwyn Bay area,
which contained around 70ngTEQ/kg.
According to ETSU, most of the dioxins end up in residues from the air
pollution control system, typically at 8101,821 ngTEQ/kg. Dioxins are
also present in bottom ash at levels of 7.5-28ng/kg. A plant taking in
100,000 tonnes of waste annually will produce 3,800 and 29,600 tonnes of
these residues, respectively, most of which are sent to landfill.
~ A preliminary assessment of trace organic compounds in household waste,
CWM 133/95, from Waste Management Information Bureau, AEA Technology, F6
Culham, Abingdon, Oxfordshire OXI4 3DB.
_\\|//_ Alan Watson C.Eng
(' O^O ') Oakleigh
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