new incineration method for soil

[Neil Tangri <ntangri@essential.org>]

Here is a frightening thought: mobile incinerators, moving from town to
town, incinerating dioxin-laden soil.


>From Pollution Online:
http://www2.pollutiononline.com/content/news/article.asp?DocID={06492E83-558
7-11D3-9A5E-00A0C9C83AFB}&Bucket=HomeLatestHeadlines

Dioxin Detoxifying Goes Better with Coke
                           8/18/99  Researchers at Tohoku University's
Advanced Materials Processing
                           Group have developed a simple, small, and,
compared with conventional dioxin
                           burners, inexpensive device for treating soil
contaminated with dioxins.

                           The system, Nikkei English News reported on Aug.
16, eliminates dioxins by
                           mixing the soil with powdered coke and then
incinerating the mixture in a
                           downward-flowing reaction chamber. With
conventional dioxin-destroying devices,
                           the Japanese researchers explained, the soil is
stirred while being incinerated in
                           a rotating furnace, consuming more energy.

                           Tests suggest that the process can detoxify
nearly 99% of the soil-trapped
                           dioxins at one-fifth the cost of the larger
equipment used in the U.S. and Europe.

                           The new treatment process involves mixing 3 to
5% powdered coke with the
                           contaminated soil and packing the mixture into a
cylindrical device. A gas burner
                           shoots flames into the top of the device,
igniting the coke while air is sucked from
                           the bottom of the cylinder.

                           The combustion at a temperature of 900 to 1100ºC
(1600 to 2000ºF) travels
                           downward, decomposing the dioxins as the air
slowly drags it through the
                           contaminated soil. The dioxin compounds
decompose into carbon dioxide and
                           hydrogen chloride, and any hydrogen chloride gas
is removed with a filter.

                           In tests of the equipment, dioxin levels were
reduced from 330 pg/g of
                           contaminated soil to less than 3.5 pg regardless
of the dioxin compound. Mixing
                           dried lime into the soil before processing can
increase the effect, the researchers
                           said.

                           The new device reportedly is small enough to be
carried on a truck for on-site
                           treatment, helping to further reduce remediation
costs.

                           The Japanese government has made it obligatory
to remove soil in urban areas
                           when the level of dioxin contamination exceeds
1000 pg/g.

                                                Edited by Paul Hersch

--

Neil TANGRI