An aerator device comprising: a housing comprising a pair of first opposing side walls (22A,22B) and a pair of second opposing side wall connecting the first opposing side walls (22A,22B), and a top wall connected to the side walls (22A,22B) to define an interior cavity of the housing; a first plate in the interior cavity and extending from an upper end to a lower end, the first plate defining a first cavity portion and a second cavity portion of the interior cavity, the upper end being spaced apart from the top wall to define a first opening, the first cavity portion and the second cavity portion being in communication with each other through the first opening; and a second plate in the interior cavity and extending from an upper end to a lower end, the second plate being between the first plate and the side wall and defining a first chamber and a second chamber of the second cavity portion, the upper end of the second plate being connected to the top wall, the first chamber and the second chamber being in communication with each other below the lower end of the second plate, and a third plate connecting the lower end of the first plate and the side wall, the third plate being spaced apart from the lower end of the second plate to define a second opening, the first chamber and the second chamber being in communication with each other through the second opening, the third plate having an opening therethrough between the first plate and the side wall thereby providing a passage for sludge to pass out of the second cavity portion and an increased pulse eruption frequency, wherein the housing has an inlet opening in communication with the first cavity portion, and an outlet opening through the top wall and in communication with the second chamber, wherein the outlet opening is a slot extending substantially parallel to the second plate, wherein the first plate and the second plate extend from a first side wall of the second opposing side walls to a second side wall of the second opposing side walls and extend parallel to the first opposing side walls (22A,22B). a housing comprising a pair of first opposing side walls (22A,22B) and a pair of second opposing side wall connecting the first opposing side walls (22A,22B), and a top wall connected to the side walls (22A,22B) to define an interior cavity of the housing; a first plate in the interior cavity and extending from an upper end to a lower end, the first plate defining a first cavity portion and a second cavity portion of the interior cavity, the upper end being spaced apart from the top wall to define a first opening, the first cavity portion and the second cavity portion being in communication with each other through the first opening; and a second plate in the interior cavity and extending from an upper end to a lower end, the second plate being between the first plate and the side wall and defining a first chamber and a second chamber of the second cavity portion, the upper end of the second plate being connected to the top wall, the first chamber and the second chamber being in communication with each other below the lower end of the second plate, and a third plate connecting the lower end of the first plate and the side wall, the third plate being spaced apart from the lower end of the second plate to define a second opening, the first chamber and the second chamber being in communication with each other through the second opening, the third plate having an opening therethrough between the first plate and the side wall thereby providing a passage for sludge to pass out of the second cavity portion and an increased pulse eruption frequency, wherein the housing has an inlet opening in communication with the first cavity portion, and an outlet opening through the top wall and in communication with the second chamber, wherein the outlet opening is a slot extending substantially parallel to the second plate, wherein the first plate and the second plate extend from a first side wall of the second opposing side walls to a second side wall of the second opposing side walls and extend parallel to the first opposing side walls (22A,22B).