Thursday, 9 July 2009


BIOCHAR pyrolysate, new gold?..........or same old, same old….

I went to the LAEC energy from waste committee today, where there was a real buzz in the air, and a hard sell for a new unheard of waste treatment method that had even been cleared by Ireland for dealing with BSE cattle!...errrrr?

Some members of the committee even thought it would be better than the old coal via coke to gas system (the “old” pyrolysis) because it was “ new technology”. So where had all the heavy metals in the sewage disappeared to I asked myself….it seemed too much of a free lunch to me…so I asked around.

“If you were pyrolysing waste materials, then I think you are right in assuming you will get a waste product at the end of the process. This could be contaminated with dioxins, PCBS, PAHs, etc. The Env. Agency would regulate as a waste, so you would need to demonstrate safety before you could apply to agricultural soils (or elsewhere I guess).”

From a leading expert in Biochar research

“4) What other impacts need to be considered?Pyrolysis can result in air pollution and particulate emissions known to have serious impacts on human health. As with conventional incineration, toxins contained within feedstocks are emitted into the air or retained in ash or and charcoal Some biochar companies are already using a wide variety of “wastes” which can include treated wood, crop residues that have been sprayed with agrichemicals, plastics, used tyres or coal mixed with other biomass. The impact of adding large quantities of potentially toxin-laden charcoal into soils must be assessed, along with air emissions from pyrolysis.”


So if some bright spark suggests a new miracle cure for dried sewage sludge, or rubber tyres, I’d take it with a pinch of salt, if I were you.

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