Crispin, Tom,
http://www.ithaka-journal.net/certificate/european-biochar-certificate-v4.2-final2012.pdf
This document includes a lengthier discussion of PAHs in char,
including how some chars are used to bind them in soils, and that
current methods for testing are problematic.
We have test results from chars that could be called ' wood
gasification' char at levels below the 4mg/kg limit for 'premium biochar'.
The high PAH levels >1000mg/kg in wood gasification chars mentioned
below needs a further explanation of the production method. Wood
gasification is to vague.
Are there any PAH tests results for TLUD rice hull chars?
Alex
On 06/02/2013 2:35 PM, Crispin Pemberton-Pigott wrote:
Dear Tom
Thanks for that:
http://www.bacatec.de/dl/Ge09_Glaser-Steiner_engl.pdf
"A further criterion for the quality of biochar is the lack of
contamination with both inorganic
(e.g. heavy metals) and organic contaminants (e.g. polycyclic aromatic
hydrocarbons (PAH),
dioxins etc.). In this study, we could only evaluate polycyclic
aromatic hydrocarbons (PAH,
Fig. 4). Although chars from wood gasification are within the
elemental composition and the
black carbon thresholds, they exhibit extremely high PAH contents
(Fig. 4). Therefore, they
are not suited for soil amendmentand thus, they cannot be classified
as biochar. Surprisingly
high PAH contents were also measured in the barbeque charcoals (Fig.
4) while all other
investigated chars had low PAH contents (Fig. 4)."
Well, there's a kick in the head. Why not? Because of chemicals
manufactured in the process that were not there in the original fuel.
That may explain a lot to some experimenters.
Regards
Crispin
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