MOBILE DEVICE FOR BIOLOGICAL TREATMENT OF BIOREACTOR-TYPE WASTEWATER

Abstract

A mobile device for biological treatment of bioreactor-type wastewater with a submerged membrane enabling treatment of greywater and blackwater has an inlet duct for effluent to be treated and an outlet duct for treated and filtered water connected to a permeate pump. The device includes a container, the interior volume of which has a parallelepiped appearance with two large vertical lateral sides, and a membrane filter having an assembly of parallel, planar filtration membranes also with a vertical appearance. The membranes are connected to a downstream collector collecting the filtered water and connected to the outlet duct. The permeate pump ensures a transmembrane flow less than the subcritical flow. At least one diffuser of fine air bubbles is located at the base of each column. Each diffuser is connected to a regulating solenoid valve and to pump, ensuring therein an airflow greater than or equal to 10 Nm.sup.3/h per diffuser.

Claims

1. A mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane enabling treatment of graywater and blackwater, the device comprising: an inlet duct for effluents to be treated; an outlet duct for treated and filtered water connected to a permeate pump; a container, having an interior volume is between 50 L and 300 L and a parallelepiped appearance with two largo vertical lateral sides, said two vertical sides forming a reservoir, wherein said reservoir has a concentration of bacteria between 3 g/L and 30 g/L, divided into N columns (2≦N≦3) delimited by N−1 intermediate vertical separation walls, and wherein each intermediate vertical separation wall is provided with an upper passage and a lower passage between columns enabling circulation of effluent between the columns; and a membrane filter having an assembly of parallel, planar filtration membranes with a vertical appearance, the filtration membranes presenting a membrane surface area of between 1 m.sup.2 and 12 m.sup.2, is said membrane filter being located in the upper part of one of said columns, wherein said membrane filter is located in a central column if N=3, under the upper passage, wherein the membranes connect to a downstream collector collecting the filtered water and connected to the outlet duct, wherein the permeate pump ensures a transmembrane flow less than the subcritical flow, and wherein at least one diffuser of air bubbles is located at the base of each column, each diffuser being connected to a regulating solenoid valve and to pumping means ensuring therein an airflow greater than or equal to 10 Nm3/h per diffuser.

2. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein direction and sense of the air flows emitted by the diffusers of fine air bubbles in their respective columns are identical, leading the diffusers of two adjacent columns to work in opposition relative to the circulation direction of the effluents, their air flow rates additionally being controlled independently.

3. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein a same transverse distance e separates the membranes from one another and the end membranes and a side or at least one median partition, the vertical sides of the membranes being situated in the immediate vicinity of the small sides of the reservoir.

4. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein the membranes are planar ultrafiltration membranes, for example made from polyester sulfone.

5. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein the membrane surface used is close to the theoretical membrane surface calculated so that the permeation flow is lower than the subcritical flow, for example 15 LMH.

6. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein the membranes are formed by rectangular planar plates with filtering outer walls and a hollow inner volume, said membranes being fastened to one another near their corners by a system maintaining their separation distance e and including a device stretching each membrane.

7. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to the claim 6, wherein the plates are kept at a distance from one another in each corner by washers forming a spacer, a circular orifice formed in each corner of each membrane forming, with the circular central opening of the washers, a channel in which a rotary shaft is inserted, the latter being provided, in said channel, with a cam.

8. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 7, wherein, when a reservoir has two columns, the shaft bearing the cam connects the two large sides of the reservoir, and its end situated in the column with no membranes is provided with a shock-absorbing stop, said shaft further including further comprising means for blocking the cam in the stretching position of each membrane.

9. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 8, wherein the means for blocking the cam comprises a nut placed on the shaft near the intermediate wall, on the column side without membranes, a notched collar protruding radially from said shaft near said wall, on the side of the column with membrane filter, being moved into contact with a notched crown or zone secured to said wall by tightening the nut toward and in contact with the partition.

10. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein the membranes are connected to a central hub comprised of spacers with a central orifice forming, with coaxial openings having the same shape as the membranes, a discharge collector for the filtered liquid, with an appearance perpendicular to the membranes, closed off at its ends by flanges, one flange resting on a first end of the hub and the other flange resting on a face of the intermediate wall opposite that on which the hub rests, the two flanges being fastened to one another so as to compress the hub adjustably.

11. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 10, wherein the aspiration duct for the filtered water is fastened to the flange resting against the intermediate wall and connected to the collector.

12. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 10, wherein the flanges are screwed by a screw having a head resting on one of the flanges and which is screwed into the other flange.

13. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, wherein the wastewater inlet duct emerges in the upper part of the reservoir, above the upper passage, and has an inner diameter smaller than 50 mm.

14. The mobile device for the biological treatment of bioreactor-type wastewater with a submerged membrane, according to claim 1, further comprising: an emptying duct emerging in the lower part of the reservoir, the upper segment of which penetrates the reservoir through the top and has a diameter at least equal to 20 mm, the lower segment, being located above the diffusers, and having a gradually flatter section with a rectangular outlet orifice having a surface area substantially equivalent to that of the upper segment.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0033] The invention will now be described in reference to the appended drawings.

[0034] FIG. 1 is a sectional schematic view of an illustration of a reservoir with two columns of the membrane bioreactor device.

[0035] FIG. 2 shows a perspective view of the various pieces of equipment said reservoir.

[0036] FIG. 3 is a schematic sectional view of the stretching system of the membranes and the collector.

[0037] FIG. 4 is a partial front elevation view of a membrane stretched using such systems.

[0038] FIG. 5 shows a schematic view of a reservoir configuration with three columns, shown very schematically.

DETAILED DESCRIPTION OF THE INVENTION

[0039] In reference to FIG. 1, the reservoir (1) is transversely divided into two columns (2) and (3) by an intermediate separating partition (4). The columns are laterally limited by the large walls of the reservoir (1), parallel to the partition (4). The column (2) contains the membrane filter (5), made up of a set of several parallel membranes (6) (in reality, thin plate membranes of about 3 mm) kept at the same distance e from one another. The two end membranes (6) are also at the same distance e from the outer wall of the reservoir (1) on the one hand and the intermediate separation wall (4) on the other hand. The membrane filter (5) comprises a collector (7) by which the water filtered by the membranes (6) is discharged via an orifice formed therein. This collector (7) is connected to an outlet duct (8) bringing the filtered water back into a hydraulic circuit to which the wastewater treatment device according to the invention belongs, for example a recycling loop for wastewater from toilets, upstream from the reservoir of the flushing system. To ensure correct discharge the filtered water, this duct (8) emerges in a permeate pump (not shown) that recirculates the filtered liquid for example toward said flushing system reservoir, or another posttreatment device, or toward the natural environment.

[0040] FIG. 1 also shows the pipes (9, 10) for supplying air for two diffusers (11, 12) situated in the bottom part of the columns (2, 3) of the reservoir (1), and connected upstream to pumps (not shown) as well as the wastewater inlet pipe (36). The upper (13) and lower (14) passages make it possible to ensure the circulation of the sludge in a loop inside the reservoir (1).

[0041] Aside from the equipment shown in FIG. 1, namely the diffusers (11) and (12) and their air supply ducts (9) and (10), the membrane filter (5) and its aspiration duct (8), and lastly the effluents inlet duct (36), the following elements, visible in FIG. 2, are also present in the reservoir: an emptying duct (37) and a plate (15) for the quick connections of the external pipes extending the various aforementioned ducts.

[0042] To ensure their correct operation, the membranes (6) of the membrane filter (5) can be stretched, in particular to preserve, between them at any location of their surface area, the same separation e, and therefore to ensure the most homogenous possible flow of the sludge, without favoring passages, but also without introducing pressure losses. The stretching device is situated at each corner of the membrane filter (5), and is based on a cam (18) (see in particular in FIG. 3).

[0043] More specifically, the membranes (6) are separated by washers (19) forming a spacer and surrounding a portion forming a cam (18) of a shaft (20) joining the large sides of the reservoir (1). Said cam portion (18) of the shaft (20) only needs to exist at the membranes (6), as in particular shown in FIGS. 3 and 4. In practice, the circular orifices that appear in each corner of each membrane (6) are coaxial to the circular openings of the washers (19), together creating a channel in which the rotary shaft (20), or more specifically its cam (18), can rotate. One of the ends of the shaft (20) includes a dog point (21) that bears on one of the walls or large sides of the reservoir (1) (not shown). The other end of the shaft (20) includes a shock absorbing stop (22) that rests against the upper wall of the reservoir (1). This stop (22) in particular serves to absorb the impacts and vibrations that could affect the reservoir, in particular when it is placed under real conditions in the rolling stock.

[0044] The shaft (20) further includes a transverse orifice (23) in which an elongate tool may be inserted to impart a rotation to the shaft (20) with the aim of stretching and blocking the membranes (6) of the membrane filter (5), as shown in FIG. 4 when the cam-forming portions (18) are separated from one another.

[0045] A nut (25) moves on the shaft (20) when it is tightened toward the intermediate wall (4), contributing to pressing a notched crown or zone (26) secured with the intermediate wall (4) against a notched collar (27) protruding radially from the shaft (20), and therefore blocking the assembly in the stretched position of the membranes (6), as shown by FIGS. 3 and 4. The membranes (6) of the membrane filter (5) are indeed stretched there, ready to be used.

[0046] The maintenance of the distance of the various membranes (6) using washers (19) situated in the four corners of the membrane filter (5) is repeated with a similar solution at the collector (7), as shown by FIG. 3. Indeed, in this location, the collector (7) is also made up of a series of spacers (28) of the washer type whereof the central orifice forms, with coaxial openings formed in the various membranes (6), a discharge collector (7) for the filtered liquid in the membrane plates (6) (symbolized by arrows). These spacers (28) have the same thickness as the washers (19), and they maintain, inside the membrane filter, the same spacing e between the adjacent membranes (6) as the corner washers (19). The filtered water flows in the collector (7) via edges of the openings formed in the membranes (6).

[0047] Two flanges (29, 30) obstruct the two ends of the collector (7), and are connected by a screw (31) resting in a recess (32) of the flange (29) while the threaded end is engaged in a threaded orifice (33) of the flange (30). The flange (30) has an aspiration duct (35) connected to the outlet pipe (8) conveying the filtered water toward the hydraulic circuit to which the bioreactor treatment device with membranes according to the invention belongs. In this specific usage scenario, the permeate pump that is positioned downstream (not shown) is capable of managing a flow rate of about 90 L/h. In reality, the device is sized to manage 15 to 20 L of wastewater per hour, corresponding to between 15 and 20 operations of a flushing system (about 0.45 L of water +0.3 L of urine containing fecal matter and dissolved toilet paper each time), and the pump is therefore largely dimensioned in this respect. In other usage scenarios, the volumes and dimensions of the components will be related to the quantity of waste water to be treated.

[0048] Emphasis has been placed several times on the positioning of the membranes (6) of the membrane filter (5) in the reactor (1) in order to avoid any favored paths of the sludge that would be detrimental to the overall filtration process. We will once again stress that, in the transverse dimension of the column, the same thickness e is preserved between all of the membranes (6) as well as between the membranes (6) and the outer wall of the reservoir (1) on the one hand, and the intermediate separation wall (4) on the other hand. In the width (not shown), i.e., on the lateral sides of the membranes (6), it is, however, also appropriate to ensure that the effluents cannot pass through a favored corridor. That is why said membranes (6) extend into the immediate vicinity of the small sides of the reservoir (1).

[0049] These membranes can have a surface area of up to about 6 m.sup.2. According to one possibility, the wastewater supply duct (36), with an interior diameter of about 47 mm, in any case smaller than 50 mm, emerges in the upper part of the reservoir (1), preferably above the level of the sludge in order to produce a hydraulic break, avoiding any possibility of siphoning. The emptying pipe (37) emerges in the lower part and, to be equipped with a large enough section to allow quick emptying, its upper part has a diameter of about 22 mm or more, while its lower part, located at a diffuser and having less space, is flat with a rectangular outlet section for example of about 24 mm×9 mm.

[0050] FIG. 5 very schematically shows a reservoir (1) with three adjacent columns (2, 2′, 3) separated by partitions (4, 4′), in which two wastewater circulation loops (symbolized by arrows showing the directions of the flows) cohabitate. Diffusers (11, 11′, 12) are placed at the bottom of the columns (2, 2′, 3), performing the same function as in the version with two columns. In such a configuration, the membrane filter (not shown) is placed in the upper part of the central column (3) shared by the two circulation loops. It works in exactly the same way as in the scenario with two columns, the circulation between columns (2, 2′, 3) being provided by upper (13, 13′) and lower (14, 14′) passages.

[0051] The illustrated configurations are not, however, exhaustive with respect to the invention, which on the contrary encompasses alternative embodiments in terms of shape, material and configuration that are within the reach of one skilled in the art.