Isn't the leftover sludge glycerol? I think it should compost fine, if done in small amounts.

Small quantites of vegetable oils can be composted but large quantites can create problems for the bacteria that digest the material. While there may well be people at work trying to find ways to compost large quantities of vegetable oils I've not yet seen anything that says they are or the results they have had.

I know of guy who spreads his unused biodiesel and the bad batches on his flower beds...so he is not composting it, he is using it raw. YMMV.

Compost maybe not be surly will decompose I might try digging little pockets in the garden to put it in and fill them up with dirt
Got to be better than the landfill

Thanks so much for the input!
It's just sludge from the bottom of the fryer- not glycerol or anything. It's just really oily, soggy breaded bits. (It's actually pretty gross and makes me never want to eat fried food again. I just imagine all that filling up my arteries. Ugh.) And we don't generate too horribly much. But we have been avoiding dealing with it for over a year, so it kind of built up.

Glad to know I'm not going to contaminate our groundwater or create some toxic environmental disaster.
Thanks!!!

Keep in mind there are some bacteria at work digesting the crude oil in the Gulf of Mexico and in places where oil was actually dumped on soil various bacteria have been found digesting it. It may take time, so dumping that kind of material where you want plants to grow, strong and healthy, may not be a good idea.

If you want to get rid of it quickly, just burn it. If you compost it, it's just going to get respired (converted to CO2 by microbes) anyway and won't leave behind any compost.

I think the idea of converting used oil to pure C02 by composting is facsinating. Would this work for used motor oil as well?

"Would this work for used motor oil as well?"

Eh, probably not. Motor oil is made up of hydrocarbons, which aren't as readily broken down as the lipids in vegetable oil. There just aren't that many microorganisms out there that have the necessary enzymes to break down hydrocarbons, which is why they're pollutants and lipids are not. It could also be that they're just harder (slower, more energy expensive) to break down even with the appropriate enzymes, but that's beyond my knowledge.

Burning for heating purposes is an EPA-approved form of recycling for used motor oil, though.

Here is a link that might be useful: uses for used motor oil