Abstract: The invention concerns an acoustic sensor (44) for identifying obstruction of a circular grit trap for recycling fine sand in an industrial water clarifying plant. The circular grit trap comprises a cylindrical body having an outer wall and having at one first end a first sand-containing fluid inlet for receiving sludge and fine sand and a first overflow outlet of fluid not containing sand orthogonal to the fluid inlet, to evacuate said sludge, and at a second end a second sand-containing fluid underflow outlet coaxial with the first fluid outlet, to recover said sand. The acoustic sensor is sensitive to the noise radiated by the flow of the sand-containing fluid in the circular grit trap and is applied against the outer wall of the cylindrical body of the circular grit trap, in the plane of the fluid inlet but not coaxially therewith.

Abstract: The segregating unit of the invention is installed in a sewer pipe section having an upstream end and a downstream end, and a peripheral wall including a floor and a ceiling. The segregating unit comprises a bar screen having two straight panels composed of horizontally disposed, vertically stacked, spaced-apart bars. The two panels span the whole width and height of the pipe in a downstream convergent fashion, thus forming a V at their adjacent edges which open adjacent the pipe floor portion into an elongated, rigid, cylindrical sleeve member radially smaller than the pipe and upwardly inclined, extending through the pipe ceiling. The sleeve member comprises an output mouth located outside the pipe section, which opens into a storage box cart. An endless screw is coaxially installed inside the sleeve member and is driven into rotation by a motor.

Abstract: The screening apparatus of the invention has a main cylindrical chamber linking a waste water inlet pipe to a refuse pipe and to an overflow outlet pipe. The waste water inlet pipe conveys water from a city sewer duct or the like, and this water is destined to be conveyed to a water treatment plant through the refuse pipe. However, during important storm water flow rate conditions in the waste water inlet pipe, the water level in the main chamber will rise since the refuse pipe will overflow due to a too large quantity of water. The screening apparatus includes a coaxial, cylindrical rotor defining a vertical through channel, and an annular grate being located intermediate the top and bottom of the main chamber and extending from the bottom edge of the rotor radially outwardly to the peripheral wall of the main chamber, where the annular grate is fixedly anchored. The rotor carries brooms adjacent the grate underface.

Abstract: The water screening apparatus of the invention includes a conduit in which is positioned a discharge pipe opening through which water flowing in the conduit is to be dispatched completely during normal water flow conditions. The discharge pipe opening is positioned adjacent the conduit bottom wall portion so that as long as the water level does not rise above it, the water is completely dispatched therethrough. A bar screen is transversely disposed inside the water conduit and downwardly slopes from the conduit upstream end to the discharge pipe opening and covers the whole conduit width. When the water level rises above the discharge pipe opening, the water flowing above the discharge pipe opening will flow through the bar screen, the latter intercepting any macroparticles beyond a set threshold level carried by the water flow.

Abstract: A rake, in which its tines are inserted and moved between the parallel, uniformly spaced, bars of a grating for debris removal. The rake includes a base and plurality of equally spaced parallel tines forming blades integrally moulded with the base out of a thermoplastic with memory characteristics. The thickness of each blade is about 1/16 its width, each blade is easily flexible thicknesswise, that is in a direction transverse to the grating bars but has practically no flexibility in the direction of the grating bars. The distance between the grating bars is two to four times the rake tines thickness so that at least two rake tines can be inserted between two adjacent grating bars.

Abstract: The screen comprises a set of spaced parallel grating bars set at an inclination of about 35 degrees. The grating bars retain solids carried by the water flowing between the bars. These solids are automatically pushed down the bars and away into a collecting trough transverse to the bars by water streams flowing within longitudinal grooves formed from the top of the bars. The cross-sectional area of each groove decreases from the upper end to the lower end of the bar, so that the water accelerating down the bar grooves will constantly fill the same.