The governing body of any such city may operate and maintain disposal works for the purification of the sewage of the city, or of any part thereof. The costs and expenses of building the same shall be borne by the city as a whole, and may be paid out of the general revenue fund; or if the governing body determines, general obligation bonds of the city may be issued therefor in any sum not exceeding three hundred thousand dollars ($300,000) for such purpose, except that in any city located within a county having a population of more than one hundred eighty thousand (180,000) and less than two hundred thousand (200,000), bonds for such purpose may not be issued in any sum exceeding one hundred thousand dollars ($100,000). Such bonds may be issued in addition to the limit of bonded indebtedness of such cities as defined by statute, except that no bonds may be issued under the provisions of this section in excess of one hundred thousand dollars ($100,000) if, within thirty (30) days of the passage of a resolution authorizing the issuance of such bonds, a petition in opposition to such issuance, signed by not less than two percent (2%) of the qualified electors in such city, is filed with the governing body of such city. If such petition is filed within the prescribed time, no such bonds may be issued unless a majority of the qualified electors approve such levy at the next primary or general election.