Section 6. A town, with the approval of the department of environmental protection, after a public hearing by said department of all parties interested, of which notice shall be given by publication in one or more newspapers, may purchase land within its limits, or take the same by eminent domain under chapter seventy-nine, for the treatment, purification and disposal of sewage. Towns or persons, owning or operating filter beds or other works for the treatment, purification and disposal of sewage shall provide and maintain works adequate for the treatment of the sewage at all times, and shall operate such works in such manner as will prevent a nuisance therefrom or the discharge or escape of unpurified or imperfectly purified sewage or effluent into any stream, pond or other water, or other objectionable result.