Abstract: Headworks for preliminary treatment of wastewater in a sewage treatment plant provides for primary filtration of grit and other coarse debris, de-ragging in a flume which carries the water away from the filter, chemical addition in a chemical mixing tank and scum removal in a scum removal tank provided with a scum skimmer. The scum removal tank may also be provided with means for pre-aerating the wastewater, secondary grit removal means, secondary de-ragging means and a partial flume for flow measurement. A debris collection device in the form of a flexible fabric sock is also disclosed.

Abstract: The apparatus includes a tank of steel, or concrete, into which the liquid to be treated is introduced vertically through a centrally located inlet at the tank bottom. Disposed inside the tank, above said inlet, are a tubular venturi-type eductor member and a conical partition member which defines a liquid mixing, coagulating, flocculating and sludge recirculating zone. As the entering liquid flows through the eductor, it draws in a very large volume of surrounding sludge to establish a high degree of sludge recirculation and mixing.

Abstract: The disclosure relates to a liquid treatment apparatus which includes a clarifier tank and an integral sludge thickener tank. Liquid enters the clarifier tank through an inlet member disposed generally centrally of the bottom wall of the member and passes upwardly through an eductor member into a mixing zone defined by a reaction cone. Recirculation of liquid and suspended particles below the cone promotes flocculation of those particles. Gravity settling also takes place in the relatively quiescent area outside the cone. The liquid inlet member is of divergent cross-sectional shape for dissipating some of the energy in the liquid and a variable speed rotary impeller is disposed in the inlet and can be adjusted to control liquid circulation according to the flow rate of influent liquid. The apparatus also includes an integral sludge thickener tank to which sludge and liquid are continuously delivered from the clarifier tank.