IT201600079570A1 - FILTERING MACHINE FOR SLIMMING THICKNESS OBTAINED FROM THE TREATMENT OF CIVIL AND INDUSTRIAL WASTE AND CONTAINING SOLID BODIES - Google Patents

Description

DESCRIPTION

Field of application

[0001] The present invention is generally applicable to the technical sector of waste water treatment and particularly has as its object a filtering machine for the thickening of sludge obtained from the treatment of civil and / or industrial waste and containing suspended solid bodies.

State of the art

[0002] The use of machines for microfiltration of suspended solid particles in civil and industrial wastewater and for the separation of sludge from the same wastewater has been known for some time.

[0003] The sludges separated from the waste water can be subsequently reused, for example as fertilizers in agriculture, and for this purpose they must first undergo an aerobic digestion process.

[0004] However, the aerobic digestion process of the sludge is strongly influenced by the presence of contaminants or debris dispersed inside them. In fact, sludges that contain high quantities of hair, lint of fabric, fibers, plastics are difficult to process and have concentrations of nutrients, such as nitrogen and phosphorus, reduced following aerobic digestion.

[0005] Such machines usually use jets of pressurized water delivered by nozzles placed on the sides of their filter elements to remove the particulate material that accumulates thereon.

[0006] A first drawback of these solutions is represented by the fact that the jets of pressurized water only partially remove the particulate material from the filtering nets and in some cases tend to push and compress it inside the same, obstructing them.

[0007] Obviously, this drawback affects the efficiency of subsequent filtration processes and forces the operator to intervene periodically to manually remove the particulate material that has not been removed.

[0008] A further drawback is represented by the fact that the filtering metal meshes tend to deform as a result of the repeated use of pressurized water jets, with a consequent decrease in filtering efficiency by the same.

[0009] From EP0388709, in the name of the same applicant, a machine is known for filtering waste water containing fibrous solids and comprising a container with a filtering chamber inside which at least two rotating and truncated cone-shaped filter discs are placed and suitable to support respective filtering networks.

[0010] The filtering discs are designed to delimit a compartment inside which the waste water to be treated is flowed with a direction parallel to the axis of development of the discs and perpendicular to their axis of rotation and deposited on the bottom of the treatment chamber the filtered fibrous material.

[0011] Furthermore, the fibrous material that detaches from the filtering nets acts itself as a trigger for the removal of the material still deposited on them by adhesiveness.

[0012] However, a drawback of this solution is represented by the fact that the filtering machine does not allow an effective recovery of the fibrous material filtered and removed from the networks, with the risk of it contaminating the freshly filtered wastewater again.

[0013] A further drawback of this solution is represented by the fact that this machine does not allow the sludge suspended in the waste water fed into the filtering chamber to be separated and thickened in an optimal manner.

[0014] From US4626351 a filtering device for waste water is known comprising a plurality of filtering discs mounted on a rotating motor shaft inside a box-like casing inside which the wastewater to be filtered is fed.

[0015] The device further comprises a plurality of stationary elements interposed between the filtering discs and capable of defining respective air spaces with the same. The particulate material that is deposited on the filtering surface of the discs accumulates inside the cavities until it comes into contact with the surface of the stationary element and is removed by the rotation of the disc.

[0016] A drawback of this solution is represented by the fact that the particular arrangement and location of the stationary elements contributes to considerably increasing the dimensions of the device, which has particularly large dimensions.

[0017] A further drawback is represented by the fact that this device only allows to filter the suspended material from the wastewater, but not to separate and concentrate the sludge dissolved therein in order to be able to reuse them later.

[0018] Finally, another drawback is represented by the fact that this filtering device does not allow an optimal disposal of the particulate material removed from the filtering surfaces of the discs.

Technical problem

[0019] In the light of the state of the art, the technical problem to be solved is to develop a filtering machine for the thickening of sludge obtained from the treatment of civil and industrial wastewater and containing suspended solids that maintains an efficiency of high filtration over time with reduced maintenance by an operator.

Presentation of the invention

[0020] A general purpose of the present invention is to solve the aforementioned technical problem by overcoming the aforementioned drawbacks, by means of a filtering machine for the thickening of sludge obtained from the treatment of civil and industrial wastewater and containing suspended solids having characteristics of high efficiency and relative cost-effectiveness.

[0021] A particular object is to provide a filtering machine of the type indicated above which allows effective removal of the particulate material that is deposited on the filtering nets.

[0022] A further object of the present invention is to provide a filtering machine of the type described above which maintains a high filtration efficiency over time.

[0023] Another object of the present invention is to provide a filtering machine of the type indicated above which allows to separate the sludge from the wastewater and to make them rapidly available for further use.

[0024] A further object of the present invention is to provide a filtering machine of the type described above which requires reduced maintenance and is particularly simple to manage.

[0025] Another object of the present invention is to provide a filtering machine of the type indicated above which has particularly reduced overall dimensions.

[0026] A further object of the present invention is to provide a filtering machine of the type indicated above which allows rapid disposal of the particulate material removed from the filtering nets.

[0027] These purposes, as well as others that will appear more clearly in the following, are achieved by a filtering machine for the thickening of sludge obtained from the treatment of civil and / or industrial wastewater and containing suspended solid bodies comprising a casing with a chamber feeding the wastewater to be filtered along a flow direction, a filtering chamber with an at least partially cylindrical bottom wall, an outflowing chamber for the filtered liquid with an outlet duct for the filtered liquid and a drainage duct for the thickened sludge.

[0028] At least one pair of filtering discs housed in the filtering chamber and keyed on a shaft substantially perpendicular to the flow direction and mutually facing each other with internal filtering surfaces suitable to delimit a compartment communicating with the drainage duct and acting motor means are also provided on the shaft to promote rotation of the filter discs in a predetermined direction.

[0029] According to a peculiar aspect of the invention, the machine comprises at least one detaching device positioned in the compartment and having opposite faces facing the internal surfaces of the discs and placed at a predetermined distance therefrom to define an interspace suitable for promoting detachment and rolling solid foreign materials deposited on the internal surfaces due to the relative speed between the device and the discs during the rotation of the latter.

[0030] Thanks to this feature, the filtering machine allows to optimally remove the particulate material deposited on the filtering nets and to ensure high filtration efficiency over time.

[0031] Advantageous embodiments of the invention are defined in accordance with the dependent claims.

Brief description of the drawings

[0032] Further characteristics and advantages of the invention will become more evident in the light of the detailed description of some preferred but not exclusive embodiments of the filtering machine according to the invention, illustrated by way of non-limiting example with the help of the following tables of drawing in which:

FIG. 1 is a perspective view of the filtering machine according to the invention;

FIGS. 2A to 4 are perspective, side sectioned and front sectional views respectively of the filtering machine of Fig. 1 in which the detaching device of the solid material is visible in a first embodiment;

FIG. 5 is a sectional side view of the filtering machine of Fig. 1 in which the detaching device of the solid material is visible in a second embodiment;

FIGS. 6 and 7 are front views in which a first and a second detail of the machine of Fig. 1 are visible;

FIG. 8 is a sectional side view of the filtering machine of Fig. 1 in an alternative operating configuration.

Detailed description of a preferred embodiment [0033] With reference to the aforementioned figures, a filtering machine for the thickening of sludge M obtained from the treatment of civil and / or industrial waste R and containing solid foreign bodies S, of the fibrous and non-fibrous type.

[0034] By way of non-limiting example, the suspended solids S may include hair, fabric fibers, plastic fragments and other particulate materials normally present in civil and / or industrial wastewater and discharges.

[0035] The sludge M separated from the thickened and filtered waste water R can be subsequently reused, for example as fertilizers in agriculture and can undergo an aerobic digestion process to increase its nutrient content, such as nitrogen and phosphorus.

[0036] In a preferred form of the invention better illustrated in FIGS. 1, 3 and 5, the machine 1 comprises a box-like casing 2 with a chamber 3 for feeding the wastewater R to be filtered along a flow direction F and a filtering chamber 4 with a bottom wall 5 at least partially cylindrical.

[0037] An outflow chamber 6 for the filtered liquid W with an outlet duct 7 for the liquid and a drainage duct 8 for the thickened sludge M are also provided.

[0038] The outflow chamber 6 will be located downstream of the filtering chamber 4 and the outlet duct 7 will be destined to convey the filtered water W towards the recycled water distribution network or another user or a drainage basin .

[0039] The selective discharge of the thickened sludge M and collected at the bottom of the filtering chamber 4 through the drainage duct 8 can be controlled by means of a suitable valve positioned along the development of the latter, not shown in the figures.

[0040] Advantageously, the casing 2 may comprise a lower body 9, preferably made of metal sheet and open upwards, closed at the top by a cover 10 also made of metal sheet and removable to allow access by a operator during maintenance operations.

[0041] The supply chamber 3 may comprise an inlet conduit 11 intended to be connected to the sewer network or with industrial or agricultural plants and may comprise a bottom wall 12 partially in common with the filtering chamber 4.

[0042] As best illustrated in FIGS. 3 and 5, a section 12 'of this bottom wall 12 of the supply chamber 3 may be inclined downwards according to the flow direction F to favor the continuous supply of the wastewater R to be filtered.

[0043] Conveniently, on the inclined section 12 'a plurality of deflectors or flaps 13 can be stably anchored with an inclination opposite to that of the section 12' to prevent the reflux of the waste R towards the inlet duct 11.

[0044] The feeding chamber 3 may provide an overflow chamber 14 suitable to fill when the level of the waste R inside exceeds a predetermined threshold value.

[0045] The filtering machine 1 also comprises at least one pair of filtering discs 15 housed in the filtering chamber 4 and keyed on a shaft 16 substantially perpendicular to the direction of the flow F and rotatable around a respective substantially horizontal axis of rotation X.

[0046] The filtering discs 15 may comprise respective hubs 17 for stable coupling to the shaft 16 and the latter may be rotatably supported on bearings, not shown in the figures, which are in turn anchored to the upper edge 18 of the body 9 to rotate around the X axis by means of suitable motor means, not shown in the figures.

[0047] Alternatively, instead of a single pair of discs 15, multiple pairs of discs equal to the first and keyed on the same shaft or on adjacent shafts, with axes parallel or coincident with the X axis, may be provided.

[0048] Each of the filtering discs 15 has a substantially truncated cone shape with internal filtering surfaces 19 which are approximately parallel to the direction of the flow F so as to carry out a so-called Dynamic-Tangential Filtration ®. This type of filtration requires that the flow of the liquid to be filtered is not orthogonal but inclined with respect to the disk development plane.

[0049] The internal surfaces 19 face each other and define a compartment 20 communicating with the sludge drainage duct 8 and adapted to be fed with the wastewater R coming from the feeding chamber 3.

[0050] As illustrated in the figures, each of the filtering discs 15 may comprise a bearing structure 21 with an outer peripheral edge 22 which is substantially circular and intended to support a plurality of filter elements 23.

[0051] Each filter element 23 may comprise a grid frame 24, with peripheral frame in the shape of a semicircle or circular sector, as illustrated in FIG. 7, on which a corresponding portion of filtering mesh 25 suitably pre-tensioned with a predetermined minimum tension is fixed by means of hot or cold gluing, heat-sealing or micro-welding.

[0052] The filtering net 25 can be constituted by a three-dimensional flat or woven mesh fabric, with a single or double layer and with porosity for example between 8 and 15 µm and even less. By way of example only, the filtering nets can be made of stainless steel, but they can also be made of synthetic material.

[0053] The filter elements 23 thus obtained are extremely light and easy to handle and include suitable universal removable connection members, not shown in the figures, so as to allow their easy replacement and / or maintenance.

[0054] The outer peripheral edge 22 of each structure 21 can be joined to the hub 17 for coupling with the rotating shaft 16 by means of a plurality of radial elements 26 suitable for supporting the filtering elements 23.

[0055] By way of example, the filtering discs may be of the type described in the patent application W02014020540 in the name of the same applicant.

[0056] Furthermore, the compartment 20 delimited by the discs 15 may have a width 1 substantially corresponding to that of the filtering chamber 4 and the edge 22 of the discs 15 may be provided with a respective lip seal 27 or similar, placed in contact with sliding with the back wall 12.

[0057] The internal surfaces 19 of the disks 15 and the gaskets 27 substantially hydraulically define the filtering chamber 4 and since the flow of the liquid to be filtered is fed from the inside of the disks 15, the solid bodies S will be retained on the internal surfaces 19 of the filter discs 15.

[0058] According to a peculiar aspect of the invention, the machine 1 comprises at least one detaching device 28 positioned in the compartment 20 and having opposite faces 29 facing the internal surfaces 19 of the discs 15 and positioned at a predetermined distance d from the latter to define a interspace 30.

[0059] The gap 30 is intended to promote the detachment and rolling up of the solid foreign materials S deposited on the internal surfaces 19 of the discs 15 due to the relative speed between the device 28 and the discs 15 during the rotation of the latter .

[0060] The detaching device 28 allows continuous removal and self-cleaning of the solid materials S deposited on the internal surfaces 19 of the discs 15 without requiring the intervention of an operator and ensure constant filtering efficiency.

[0061] As best illustrated in FIGS. 3 and 5, the machine 1 may comprise a chamber 31 for collecting the extraneous solid materials S removed from the discs 15 and located downstream of the filtering chamber 4.

[0062] The solid materials S removed from the internal surfaces 19 will be transported into the collection chamber 31 by the rotating filter discs 15 without falling into the thickened sludge M at the bottom of the filtering chamber 4 and an opening 32 communicating with the external for the discharge of solid materials from the collection chamber 31.

[0063] Advantageously, the predetermined distance d of the gap 30 between the detaching device 28 and the internal surfaces 19 of the discs 15 can be chosen within an interval between 1cm and 4cm.

[0064] In this way, when the accumulation of the solid bodies S on the internal surfaces 19 reaches a thickness equal to this predetermined distance d, the material S comes into contact with the respective face 29 of the detaching device 28 and is removed by friction from the relative rotation of the discs 15, rolling up inside the gap 30.

[0065] In addition, the material S already detached in the form of rollers or curls formed within the gap 30 acts as a trigger for the removal of further material S still deposited on the internal surfaces 19 of the discs 15 by adhesiveness.

[0066] Eventually, the device 28 may be covered with a layer of friction material chosen within the group comprising steel, plastic or textile fibers, in order to increase the friction during the rotation of the discs 15.

[0067] The machine may comprise a chute 33, better illustrated in FIG. 5, integral with the casing 2 and having an open end 34 placed in the compartment 20 to convey a particulate abrasive material inside it.

[0068] The abrasive material will be able to insinuate itself into the interspaces 30 between the detaching element 28 and the discs 15 to act as a trigger and facilitate the detachment of solid foreign materials S.

In a first embodiment illustrated in FIGS. from 2A to 4, the detaching device 28 is stationary and includes a pair of sections 35 housed inside the compartment 20 and anchored to the bottom wall 5.

[0070] Advantageously, the sections 35 may comprise an upper edge 36 of circular shape and complementary to the shaft 16 so as not to hinder its rotation.

[0071] The stationary sections 35 may also have different shapes from those illustrated in the figures provided they are suitable for rolling up the solid bodies S, and may be placed in different positions with respect to the filtering discs 15, without thereby departing from the scope of protection of the invention.

[0072] In a second embodiment, illustrated in FIG. 5, the detaching device 28 is mobile and comprises a pair of rotating rollers 37 having ends fixed, respectively to the shaft 16 and to the casing 2, and rotating on respective Y axes substantially parallel to the flow direction F.

[0073] In this embodiment, the opposite faces 29 suitable for defining the respective interspaces 30 with the internal surfaces 19 of the discs 15 will be constituted by the external surfaces of the rollers 37.

[0074] Jet washing means 38 for the discs 15, illustrated in FIG. 6, adapted to be activated following the removal of the foreign material S by the detaching device 28.

[0075] The washing means 38 may comprise a pair of first tubes 39 placed on the sides of the disks 15, facing their external surfaces 40 and fed by a washing fluid under pressure. Furthermore, each tube 39 may comprise a plurality of nozzles 41 for dispensing the washing fluid.

[0076] In an alternative form of the invention, better illustrated in FIG. 8, the inlet 11 and outlet 7 ducts can be placed in the upper portion of the machine 1 and a dividing wall 42 may be provided integral with the casing 2 and placed in the compartment 20.

[0077] The dividing wall 42 will be adapted to divide the filtering chamber 4 into two half-chambers in fluid communication, respectively, with the inlet duct 11 and with the outlet duct 7 and in this way it will be possible to increase the surface of the discs 15 available for filtering.

[0078] From what has been described above, it is evident that the filtering machine for thickening the sludge from wastewater achieves the intended purposes and in particular allows for improvements in performance and construction and maintenance costs.

[0079] The filtering machine according to the invention is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept expressed in the attached claims. All the details can be replaced by other technically equivalent elements, and the materials can be different according to the requirements, without departing from the scope of the invention.

Industrial applicability

[0080] The present invention is industrially applicable as it can be realized on an industrial scale by industries belonging to the sector of plants and devices for the treatment of waste water.

Claims (11)

R I V E N D I C A Z I O N I 1. A filtering machine (1) for the thickening of sludge (M) obtained from the treatment of civil and / or industrial wastewater (R) and containing solid bodies (S) of fibrous and non-fibrous type, which machine (1) comprehends: - a box-shaped casing (2) with a feeding chamber (3) for introducing the wastewater to be filtered (R) along a flow direction (F), a filtering chamber (4) with a bottom wall (5) at least partially cylindrical, an outflow chamber (6) for the filtered liquid (W) with an outlet duct (7) for the same liquid and a drainage duct (8) for the thickened sludge (M); - at least one pair of filtering discs (15) housed in said filtering chamber (4) and keyed on a shaft (16) with axis (X) substantially horizontal and perpendicular to said flow direction (F), said discs (15) being mutually facing and having internal filtering surfaces (19) to delimit a compartment (20) communicating with said drainage duct (8); - motor means acting on said shaft (16) to promote the rotation of said filter discs (15) in a predetermined direction; characterized in that it comprises at least one detaching device (28) positioned in said compartment (20) and having opposite faces (29) facing said internal surfaces (19) of said discs (15), said faces (29) being placed at a predetermined distance (d) from said internal surfaces (19) of said discs (15) to define an interspace (30) suitable for promoting the detachment and rolling up of the solid bodies (S) deposited on said internal surfaces (19) by effect of the relative speed between said device (28) and said discs (15) during the rotation of the latter. 2. Machine according to claim 1, characterized in that it comprises a collection chamber (31) for the solid foreign materials (S) removed from the disks (15) located downstream of said filtering chamber (4) and having an opening drain (32) communicating with the outside. 3. Machine according to claim 1, characterized in that said predetermined distance (d) is chosen within an interval between 1cm and 4cm. 4. Machine according to claim 1, characterized by the fact that said detaching device (28) is covered with a layer of a friction material chosen within the group comprising steel, plastic or textile fibers. 5. Machine according to claim 1, characterized by the fact that said detaching device (28) is stationary and comprises a pair of sections (35) housed inside said compartment (20) and anchored to said bottom wall (5). 6. Machine according to claim 1, characterized in that said detaching device (28) is mobile and comprises a pair of rotatable rollers (37) on respective axes (Y) substantially parallel to said flow direction (F), said opposite faces (29) being constituted by the external cylindrical surfaces of said rollers (37). 7. Machine according to claim 1, characterized in that each of said filtering discs (15) comprises a supporting structure (21) with a substantially circular outer peripheral edge (22) intended to support a plurality of filtering elements (23), said outer peripheral edge (22) being joined by a plurality of radial elements (26) to a central hub (17) which can be anchored to said shaft (16). 8. Machine according to claim 1, characterized in that said supply chamber (3) comprises an inlet duct (11) and a bottom wall (12) partially in common with said filtering chamber (4), said bottom (12) being inclined downwards according to said flow direction (F) and being provided with a plurality of deflectors (13) with an inclination opposite to said bottom wall (12), anchored to the latter to prevent the backflow of the wastewater (R) towards said inlet duct (11). 9. Machine according to claim 1, characterized by the fact of comprising a chute (33) having an open end (34) positioned in said compartment (20) to convey inside it a particulate abrasive material able to penetrate said interspace (30 ) to favor the detachment of said solid foreign materials (S). 10. Machine according to claim 1, characterized in that it comprises jet washing means (38) having at least one pair of first longitudinal tubes (39) placed at the sides of said pair of discs (15) and fed by a washing fluid under pressure, each of said tubes (39) being provided with a plurality of nozzles (41) for dispensing the washing fluid. 11. Machine according to claim 1, characterized in that inside said compartment (20) there is a dividing wall (42) integral with said casing (2) to divide said filtering chamber (4) into two communicating half-chambers fluidics with said inlet conduit (11) and with said outlet conduit (7