Consider the following statements in respect of aerated grit chamber:
1) The grit accumulates at the bottom in advancing spiral-flow aeration tanks, location ally preceded by grit chambers, led to the eventual development of aerated grit chambers.
2. The excessive wear on grit handling equipment is a major factor for the popularity of aerated grit chambers.
3. Aerated grit chambers are designed to provide detention period of 1 minute at maximum rate of flow.
4. Diffusers are located at 0.45 m to 0.6 m above the bottom of the chamber.
Which of the above statements are correct?