Section 151. No person shall occupy or use a building for carrying on the business of slaughtering cattle, horses, mules, sheep or other animals, or for a melting or rendering establishment, or for other noxious or offensive trade and occupation, or permit or allow said trade or occupation to be carried on upon premises owned or occupied by him, without first obtaining, after a public hearing has been held thereon, the written consent and permission of the mayor and city council, or of the selectmen, or, in any town having a population of more than five thousand, of the board of health, if any, of the town where the building or premises are situated. This section shall not apply to any building or premises occupied or used for said trade or occupation on May eighth, eighteen hundred and seventy-one; but no person who used or occupied any building or premises on said date for said trades or occupations shall enlarge or extend the same without first obtaining the written consent and permission of the mayor and city council or the selectmen, or, in any town having a population of more than five thousand, of the board of health, if any.