A wastewater treatment device comprises: a vessel comprising an inlet for receiving an influent stream, a grit outlet and a floating-matter outlet; a separator disposed within the vessel, wherein theseparator comprises a tray assembly connected to the inlet and the grit outlet, the tray assembly comprising a plurality of nested tray units which define a separator axis and are spaced apart from one another along the separator axis, each tray unit comprising: a substantially conical tray which is aligned along the separator axis; and an aperture in the tray disposed at the separator axis and incommunication with the grit outlet; wherein the wastewater treatment device further comprises a spray nozzle configured to deliver a jet of fluid towards a surface of water within the vessel, whereinthe spray nozzle is angled towards the direction of the floating-matter outlet to force floating matter accumulated on the surface of the water towards and out of the outlet.