For the purpose of owning, operating, constructing, and equipping any sewerage disposal system and plant or plants or improving or extending any existing system or for the purposes stated in the County Industrial Sewer Construction Act, any county may issue and sell the general obligation bonds of the county upon compliance with the provisions of section 23-3621. Such bonds shall not be sold or exchanged for less than the par value and shall bear interest which shall be payable annually or semiannually. The county board shall have the power to determine the denominations of such bonds and the date, time, and manner of the payment. The amount of such general obligation bonds, either issued or outstanding, shall not be included in the maximum amount of bonds which any such county may be authorized to issue and sell under any statutes of this state.