[nlperguiy]

Whey is waste in the dairy industry, yet it's sold profitably as a dietary supplement and used all over the processed food market.

Unfit oranges, apples etc. are waste to the fruit producers, but juices love it.

Cow shit is a complete waste but is used as a fertilizer. Although, a bunch of cow shit is also thrown into rivers.

Wasted food is ground into powder and given to animals.

I guess food might be an exception. I don't know if there exists something similar for oil, chemicals etc.

[pjc50]

Well, yes, the difference between "waste" and "feedstock" is whether there is some valuable use for the thing and whether it can be easily collected. Insecticide once used cannot be easily collected again.

Much of the history of the petrochemicals industry is trying to find valuable things to do with less-valuable fractions and non-oil stuff that comes up from wells. Of course, if it's not valuable it tends to be flared off and contributes to global warming.

> Wasted food is ground into powder and given to animals

.. although since the CJD epidemic I think this is extremely limited. By regulations.