Mich. Comp. Laws § 123.309

Sec. 9. For the purpose of acquiring, constructing, improving, enlarging or extending facilities for the collection or disposal, or both, of garbage or rubbish, or both, or for the purpose of refunding bonds previously issued, the authority may issue self-liquidating revenue bonds in accordance with the provisions of Act No. 94 of the Public Acts of 1933, as amended, being sections 141.101 to 141.139 of the Compiled Laws of 1948. No such bonds shall be a general obligation of the authority but shall be payable from revenues only.