Any two or more sanitary districts heretofore or hereafter created in any county under the provisions of this article may be merged into a single district by the governing body of the county, by ordinance, upon the petition of not less than 50 qualified voters residing within the boundaries of each of the districts desiring to be so merged, which ordinance shall prescribe the metes and bounds and the name or other designation of the single district created by such merger. From and after the adoption of such ordinance, the governing body of such county shall, as to the single districts so created, have all the powers and duties, and be subject to all the conditions and limitations prescribed by § 21-118, and all funds then on hand to the credit of each of the districts so merged shall be merged into a single fund for the use and benefit of the consolidated district, unless otherwise ordered by the governing body of the county upon the hearing next herein provided for. Upon the filing of the petition, a hearing shall be had before the governing body of the county, after notice as provided by § 21-114, which notice shall require all interested parties to appear and show cause, if any they can, (i) why the funds then on hand to the credit of each of the merged districts should not be merged into a single fund for the purpose above mentioned; and (ii) why a special tax should not be levied on all the property within the limits of the consolidated district, subject to local taxation, sufficient to pay the interest and create a sinking fund for payment of the principal at maturity of any then outstanding bonds theretofore issued by any one or more of the districts so merged. Upon the hearing, such ordinance shall be adopted as to the governing body of the county may seem equitable and proper, concerning the combination of the funds on hand to the credit of each of the districts so merged and the levying of a special tax on all the taxable property within the limits of the consolidated district, for the purposes hereinabove mentioned, provided that such ordinance shall preserve and protect the rights of the holders of any such outstanding bonds, whose rights and interests shall not be limited or affected by any of the provisions of this section.