TCDD and other dioxins are highly toxic, even in small amounts. Their disposal should be tackled professionally and this will proceed differently when the dioxins are gaseous, as aerosols, in liquids, in sludge, or on a solid substrate, such as filter dust, fly ash, or activated carbon. I assume that your dioxins are solids.

There are numerous tested methods to destroy dioxins, yet only one method is simple: incineration. Introduced into a well operated furnace or kiln, dioxins will often be destroyed better than 99%, in some cases better than 99.99%. The latter applies to a cement kiln with the dioxins entering at the lower side, together with fuel, generally coal, heavy fuel oil, or natural gas. Please note that special licenses will be required to carry out this operation.

Given the complexity of any full-scale industrial plant it is necessary that - before proceeding - a thorough risk analysis be made. This means that everything that could go wrong should be identified beforehand. Introducing dioxins into conventional mechanical grate incinerators carries a risk that the dioxins or their carrier would not be burned and destroyed, but rather would report to the grate siftings. One other undesirable occurrence is that dioxins in part would evaporate during their loading into a furnace and disperse into the feed and possibly elsewhere.

A second option was developed by Prof. Hagenmaier and Deutsche Babcock and has been applied extensively in Japan for treating fly ash. It involves treatment in a closed vessel, typically for 1 h or more at temperatures of 400 °C under an inert atmosphere. Destruction as well as dehalogenation occurs. The latter converts relatively innocuous OCDD into lower chlorinated congeners of higher toxicity.

There are many studies highlighting these and (especially) other possibilities. UNEP and UNIDO actively support destruction of dioxins, PCBs, etc. and published studies in this field. Their website will allow ready access to such studies.

Dear Alfons Buekens,

Thank you so much for your rapid and comprehensive response and guidance.

We are using TCDD in laboratory in culture conditions. Is it OK if we send the wastes for incineration along with other infectious wastes of hospital? 

Thanks again.

I would not send any dioxin containing material together with "normal" infectious waste to be incinerated.

Dr Buekens advise is quite clear to me. Find a designed incineration plant with is prepared and capable of dealing with this special hazardous material.

Any other procedure has unknown risks which may kick back on you.

This answer is indeed very helpful: to destroy infectious waste it suffices to maintain it at temperatures sufficient to destroy germs. In this case you want to (a) destroy fairly stable molecules and (b) make sure that no new dioxins are formed and emitted with the flue gas. Some hospital incinerators are adequately equipped to take care of (b). minimum requirements would be: ensure that dioxins entering cannot disperse out of the plant and flue gas treatment with activated carbon adsorption and/or catalytic DeNOx. In Belgium the effluent of incinerators is monitored continuously for dioxins, ie, continuous sampling, analysis every 2 weeks. This feature is expensive, yet reassuring.

Thanks a lot for your help. How about the fluid waste containing dioxin? 

I imagine that the absolute amounts are quite low and that the fluid waste are composed of highly flammable fluids, such as toluene or other organic solvents. The reason for this hypothesis is that dioxins would normally never appear in aqueous midst.

Fluids containing dioxins could probably be mixed with oil and directly fired, under suitable conditions (the 3 T's leading to complete combustion).

In this case, if you know how much dioxins enter your burner, you could guess how much would possibly survive in a worst case hypothesis (eg, 1 %) and then calculate how much would remain in the flue gas. If this remains below 1 to 10 ng I-TEQ/Nm3 the risk for the environment would be minimal, given the limited time required for disposal of your waste. Most exposed would be grazing cattle, such as cows. Since in Iran you often have a clear sky photolytic decomposition should do its work well.

The best conditions for destruction would be a low-concentration of dioxins dissolved in a flammable solvent. The worst would be a fluid with sediments or sludge. I would recommend filtering out all suspended solids prior to firing.

Dioxins have often shown NOT to follow what was expected on the basis of previous research. In the USA in the eighties and nineties Prof. Dellinger practised a pragmatic Question/Answer approach regarding incinerating various kinds of hazardous waste. You could retrieve it from literature searching for his name + the key words Test Burn.