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Dear community,

I use ecoinvent 3.5 version and there is a process named "market for hazardous waste, incineration" that I want to use. The unit is in kg. But does the process materialize the added consumption for a treatment of 1kg of waste by this method (so I have to add in the output i.e "waste aluminium") or does the process materialize 1 kg of a standardised hazardous waste, treated by this method (and I don't have to add another process) ? I have made a scheme for you to better understand my issue.

Thank you in advance.


in openLCA by (490 points)

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Yeah, in ecoivent 3.5 we still use (as ecoinvent "itself" does up to today, and e.g. SimaPro too) the double negative waste approach: a process that provides the service of waste treatment has a product on the ouput side (treatment of waste), with a negative sign, and a process that has waste output sent to this process has waste on the input side, also with a negative sign. That is (if I understand correctly) the second picture (where you do not mention the negative sign though).

In openLCA, since version 1.7 or so, you can also use the other approach: model the flow as waste flow, let it be output of the process that has waste output and input of the process that treats it. And do not use negative signs. That is your first picture.

Hope this helps,


- in newer versions of ecoinvent, > 3.5, we always use the second approach, so your first picture.
by (490 points)
Hello ! Thank you for your answer, that I can complete with the one by the ecoinvent team :

The "market for hazardous waste, for incineration" dataset models the transport of 1kg hazardous waste from the production site where it is generated to the incineration facility. The market represents a generic transport process for any kind of waste that can be characterized as hazardous.

From your side as a user, you do not have to add any specific waste input like waste aluminum, as it is already included indirectly through the linking of the supply chain. However, if you feel that the accounted transport distances are not suitable for your kind of study, you can adapt this by inserting the distances that fit the needs of your model.