Tenn. Code Ann. § 7-55-112

The governing body of a municipality issuing bonds pursuant to this chapter shall prescribe and collect rentals for industrial buildings and shall revise such rentals from time to time whenever necessary so that the income and revenues to be derived from such rentals will always be sufficient to pay when due all bonds and interest on the bonds for the payment of which such revenues are pledged, including reserves for the payment of the bonds and interest, and to provide for all expenses of operation, maintenance, and depreciation charges of such industrial buildings. All funds arising under this chapter shall be kept separately and apart from other funds of the county, city or town, as the case may be.