Abstract: A system for removing pollutants from a liquid. The system has a tank with a bypass chamber, a treatment chamber, inlet and outlet ports. A dividing wall is located within the tank and defines the bypass chamber and the treatment chamber. The dividing wall has an inlet opening, one or more outlet openings, retaining rods forming a retention space at least partially below the inlet opening, and a vertically-extending weir between the inlet opening and the outlet opening(s). The inlet opening receives polluted liquid from the inlet port and the one or more outlet openings output a cleaned liquid to the outlet port. A float in the treatment chamber is adapted to float in a retention space formed by the retaining rods. The float is adapted to rise against the inlet opening when a fluid level in the treatment chamber reaches a predetermined level to substantially block the inlet opening.