The bonds authorized by this chapter, the income therefrom, all mortgages or deeds of trust executed as security therefor, all lease or purchase agreements made pursuant to the provisions hereof, and all purchases required to establish the enterprise and financed by bond proceeds shall be exempt from all taxation in the State of Mississippi except the contractors' tax imposed by Section 27-65-21 and the tax levied by Section 27-65-24(1)(b) and all projects and the revenue derived from any lease thereof shall be exempt from all taxation in the State of Mississippi, except the tax levied by Sections 27-65-21 and 27-65-24(1)(b). From and after July 1, 1989, there shall be no new exemption under this section or under Chapter 10, Title 57, Mississippi Code of 1972, from ad valorem taxes levied for school district purposes. The time of any ad valorem tax exemption provided for hereunder shall not exceed a total of ten (10) years, which shall run from the date of completion of the project. In no event shall the term of the ad valorem tax exemption provided for hereunder be limited, terminated or otherwise affected by payment in full of the bonds issued under this chapter or by the change from a leasehold to a fee title in the enterprise financed with bonds issued under this chapter.