Abstract: A sludge dewatering system comprising a moving foraminous belt (10) having a horizontal conveying run on which sludge is carried to permit drainage of water therefrom through the belt. In accordance with the invention a row of deflectors (12) are mounted on a pivotal cross beam (13) extending over the belt (10). Each deflector has a leading edge (19) and a pair of diverging and upwardly concave walls (21) whereby sludge proceeding along the conveying run of belt (10) is divided overturned and compressed by the deflectors.

Abstract: A penstock or sluice gate door constructed by providing a stack of steel tubes (11) preferably of rectangular cross-section, which are stitch welded together at (12). There are added welded side plates (13), a central stainless steel spindle (14) and bolts (18) for lifting equipment, and the so-formed panel is placed in a mould and encapsulated with an impervious material. If desired side and bottom sealing strips (22, 23, 21) may be integrally formed during encapsulation. The resultant door is lightweight and non-corrodible, and its strength is determined by the wall thickness of the tubes (11) which will be selected accordingly.

Abstract: A penstock or sluice gate door constructed by providing a stack of steel tubes (11) preferably of rectangular cross-section, which are stitch welded together at (12). There are added welded side plates (13), a central stainless steel spindle (14) and bolts (18) for lifting equipment, and the so-formed panel is placed in a mould and encapsulated with an impervious material. If desired side and bottom sealing strips (22, 23, 21) may be integrally formed during encapsulation. The resultant door is lightweight and non-corrodible, and its strength is determined by the wall thickness of the tubes (11) which will be selected accordingly.

Abstract: A flap valve comprising an annular frame (10) defining an opening (11) through which liquid may flow in one direction, a closure flap (14) for said opening connected to the frame (10) by a hinge member (15), and a valve seat (12) against which the closure flap (14) may close to prevent reverse flow of liquid through the opening. The frame (10) may be bolted (at 18) to a wall or pipe flange, with integral sealing ribs (24, 25) on the rear face of the frame avoiding the need for a separate gasket. The entire assembly comprising frame, closure flap, hinge, valve seat and sealing ribs, is integrally moulded from a plastics material and is reinforced where appropriate by embedded steel plates (19, 20 and 21).

Abstract: An outlet assembly for a liquid distribution system of the type whereby liquid is to be deposited onto a treatment bed (13) from one or more apertured distributor pipes (14) connected to a rotary (or linear) supply head (10) the assembly comprising longitudinally spaced apertures (15) opening upwardly in the pipe wall and clamped to the pipe over each aperture (15) a distribution tray (16) extending generally transversely but angularly from the pipe and having a generally horizontal surface (17) with upright side walls (18) so that liquid may flow upwardly through the apertures (15) and be channelled outwardly along the trays to be deposited from the outer ends thereof. The larger than usual apertures (15) ensure that no blockages occur from solids within the liquid, whilst uniform and constant distribution is ensured.

Abstract: Apparatus for dewatering sludge comprising a moving foraminous conveyor belt (10) driven in a single direction with a horizontal conveying run (11). Sludge to be dewatered is fed onto the belt at an input end of the conveying run so that liquid may drain from the sludge through the belt. Part way along the belt is disposed at least on ramp (21) having its lower edge in contact with or just above the belt surface to cause sludge to rise up the ramp thus enhancing the dewatering process. A plurality of spaced fingers (26) extend forwardly from the top of the ramp (21) thus leaving strips of the belt (20) free of sludge forwardly of the ramp and fingers.

Abstract: A sludge thickening apparatus for dosing sludge with a cationic polyelectrolyte, allowing time for the development of a floc structure, placing the dosed sludge onto a surface through which liquid may drain freely by gravity in such a manner that the floc structure is retained, and removing the thickened sludge from said structure.

Abstract: Apparatus for thickening sludge comprising a driven foraminous belt (10) having a conveying surface arranged at least substantially horizontally, a chute (14) for feeding a matt of sludge onto the belt (10) at one end of the conveying run, and a plurality of parallel flexible strips (21) of material attached at one end to the output end of the chute (14) and allowed to rest freely upon the belt (10) at the other end, whereby the sludge passes onto the belt in one or more strips whose width is substantially less than that of the belt, thus to leave one or more zones of the belt free of sludge to permit drainage of water therefrom through the belt, there being a plurality of deflecting members (22) disposed downstream of the output ends of the strips (21) and adapted to deflect a portion of each strip of sludge onto the next adjacent part of the belt left free of sludge thus to produce a matt thereof of substantially uniform thickness extending across the belt.

Abstract: An aerator comprising a support member in the form of a flat plate which is adapted, when the aerator is in use, to lie in a horizontal plane and to be rotated about its central vertical axis, a plurality of angularly spaced blades secured to the underside of said plate and each extending radially from a central region thereof towards its periphery, each said blade having a maximum depth beneath a horizontal datum at a position intermediate its ends, and being provided with a plate secured to its lower edge and extending on both sides of the blade along at least a portion of that part of the length of the blade between its outer end and the position of maximum depth.