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Comment by tonyarkles | Hacker News Reader

I’m honestly just stuck thinking about that cleanup. Like… hydrovac is great, but how do you clean out a hydrovac truck filled with butter. And after you get it out, then what? In Madison they temporarily stored it in sanitary sewer holding ponds but that’s not a viable final destination. Does it eventually end up at the landfill?!

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I guess you would add it a bit at a time to the organic waste stream, at a low enough proportion that it doesn't swamp the system. At least, as long as it's not contaminated with stuff that would rule that out. Then, it probably goes to one of the waste burning power plants.

>but how do you clean out a hydrovac truck filled with butter.

Steam or barely subcritical water.

Butter is mostly animal fat. Any reason it couldn't be sent down the same waste-processing stream as restaurant cooking grease?

Volume presumably, as well as being mixed with whatever byproducts of a burning warehouse.

You can actually make biodiesel from butter. It’s about 80–82% fat, so first you clarify it to remove the water and milk solids, then react the fat with methanol and a catalyst like sodium hydroxide. That gives you fatty acid methyl esters (biodiesel) and glycerol as a byproduct.

In theory, a kilo of butter could yield around 0.9 litres of biodiesel. The main problem, apart from the ridiculous cost, is that butterfat has a lot of saturated fatty acids, so the resulting fuel has pretty terrible cold-weather properties.

Of course in this case i suspect it was probably not quite pure.

This is why they never show robovac commercials with butter/grease as demonstration. It's always cereals and rice candy, and stuff like that.

If it were my decision I would have found two gigantic slices of bread and made the world's biggest cheese sandwich - think of the tourism revenue!

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