All the costs and expenses occasioned by the construction of any such disposal works, including the purchase or condemnation of land therefor and including the purchase or condemnation of land for the construction of sewers, drains, pumps and other appurtenances within or without the city used in connection with such disposal works, shall be borne by the city as a whole and paid out of the general revenue fund or by the issuance of internal improvement bonds. Such bonds shall be issued as provided by law, and shall not be issued in excess of the amount of the improvement, except that any installment coupons shall include the interest on such installments to the maturity thereof. The bonds issued under this act shall not be included in fixing the limit of the bonded indebtedness of the city issuing such bonds.