(2) The commission shall issue a certificate of convenience and necessity to any person engaged in the construction or operation of a sewage disposal service as mentioned in subsection (2) of Section 77-3-11 on August 9, 1968, for the construction or operation then being conducted, without requiring proof that public convenience and necessity will be served by such construction or operation, and without further proceedings, if application for such certificate is made to the commission within six (6) months after August 9, 1968. Pending the filing of such application and the issuance of a certificate, the continuance of such construction or operation shall be lawful. Except as otherwise specifically provided by subsection (2) of Section 77-3-11 or by this subsection, that portion of the business of a public utility dealing with the operation of a sewage disposal service as provided by subsection (2) of Section 77-3-11 shall be subject to provisions of this chapter, in like manner and with like effect as if such business had been included within the definition of a "public utility" in the original enactment of this chapter.