Can they? Of course they can. Should they? I would advise not doing anything that increases the solids load. A lot depends on your septic tank. I have one that has not needed to be emptied in 30 years because I am very careful with it.

Before installing a garbage disposal, also check the slope of your drainpipe. You do not want to spend all that money on an install only to find that you spend half the year unclogging your drain. The convenience of a garbage disposal is not worth the plumbing bills. Consider getting a drain basket for the kitchen sink.

They can but it is not a good idea. A garbage disposal can really screw up a septic.

It's not recommended because the garbage does not decompose and will eventually clog the system.

Check with your city/county building dept.

Nope. It can clog the system.

Can they? Yes, of course.

It is not a good idea, though.