Horizontal-axis aerator for purification of waste water

A horizontal axis aerator for use in a waste water purification system and adapted to be mounted across and partially immersed in a body of waste water to be treated and rotated therein, said aerator comprising:

• a cylinder having an axis and adapted to be mounted with said axis extending horizontally;
• a first series of parallel blades on the surface of said cylinder and extending in directions nonparallel to said axis;
• a second series of parallel blades on said surface of said cylinder and extending in directions nonparallel to said axis;
• said directions of said first series of blades being opposite to said directions of said second series of blades with respect to said axis;
• said first and second series of blades intersecting each other, such that upon the aerator being partially immersed in a body of waste water to be treated and being rotated therein, at any rotational position of said aerator about said axis a constant portion of the total blade length of all of said blades of said aerator will be immersed in the waste water;
• and
• each said blade being inclined with respect to said surface of said cylinder in a direction opposite to the direction of rotation.