53 Pa. Stat. § 15732
Whenever any city of the first class shall issue such non-debt revenue bonds, the authorities thereof may sell the same, or any portion thereof, at private sale to the United States of America, or any agency, instrumentality or corporation thereof, or to the sinking fund of the city. Any bonds not so sold shall be sold to the highest responsible bidder, after public notice by advertisement, once a week for three weeks, in at least one newspaper of general circulation published in the city. No bid for such bonds at less than par value shall be accepted. When bonds shall be advertised for sale, as herein provided, and no bids have been received, then it shall be lawful for the city to sell the same at private sale for not less than par value and accrued interest.
All such bonds shall be payable in not more than thirty years from the date of their issue, shall be issued in series payable in annual installments as may be determined by the city, and shall bear interest at a rate not exceeding six per centum per annum.
Said bonds shall have all the qualities of negotiable instruments under the law merchant and the negotiable instruments law of the Commonwealth of Pennsylvania.
Any city may enter into any deeds of trust, indentures or other agreements with any bank or trust company or other person or persons in the United States having power to enter into the same, including any Federal agency, as security for such bonds, and may assign and pledge all or any of the revenues or receipts of the sewer system or sewage treatment works thereunder. Such deed of trust, indenture or other agreement may contain such provisions as may be customary in such instruments, or as the city may authorize, including (but without limitation) provisions as to--
53 P.S. § 15732