Any valid ordinances, bylaws or regulations adopted prior to October 1, 1957, under the provisions of the general statutes shall remain valid until altered or repealed under the provisions of this chapter. Nothing contained in this chapter shall affect the powers granted to any municipality to enact ordinances, regulations or bylaws under the provisions of any special act nor shall it affect any valid ordinance, regulation or bylaw enacted under such provisions before or after October 1, 1957.