Section 76. The director of the division of marine fisheries may construct and operate shellfish purification plants for the treatment of shellfish taken from areas determined under section seventy-four or any corresponding provisions of earlier laws, to be contaminated, and may operate such existing purification plants to serve such areas as he may deem necessary for these purposes. Said director may acquire by purchase, gift, lease or otherwise, or take by eminent domain under chapter seventy-nine, such land and buildings thereon as may be necessary for the purposes of this section. Said director or his designee shall have sole authority over the acceptance, treatment and discharge of shellfish at such plants, subject to the rules and regulations, which the department of public health is hereby authorized and directed to adopt, relative to the protection of the public health in the consumption of such shellfish.