Patent ID: 8070963

Claim:
A sedimentation tank, comprising: a perforated plate spaced from an upper end of the sedimentation tank dividing the sedimentation tank into an upper chamber and a lower chamber; an inlet adapted to inlet fluid into the tank; a first outlet, positioned above the perforated plate for outletting a clarified fraction of the fluid; wherein only the perforated plate filters the fluid to provide the clarified fraction of the fluid; a second outlet positioned at a bottom of the tank, for outletting a concentrated sludge fraction of the fluid; a pump positioned in proximity to the perforated plate and within the sedimentation tank; and a washing mechanism that differs from the perforated plate, positioned at least partially above the perforated plate in proximity to the perforated plate and within the sedimentation tank; wherein the pump is adapted to provide a washing fluid to the washing mechanism when a pressure level of fluid in the sedimentation tank is below a predefined level; and wherein the washing mechanism washes an upper surface of the perforated plate by the washing fluid.