WO2015160243A1

WO2015160243A1 - Assembly of a flocculation device, an ozone introduction device and a separator device and method for operating such an assembly

Info

Publication number: WO2015160243A1
Application number: PCT/NL2015/050240
Authority: WO
Inventors: Arie Kluit; Hendrik Willem Herman Menkveld; Nadina Catherina BOELEE; Menno-Martijn HOLTERMAN; Antonie RUITENBERG
Original assignee: Nijhuis Water Technology B.V.
Priority date: 2014-04-14
Filing date: 2015-04-14
Publication date: 2015-10-22
Also published as: NL2012619B1; NL2012619A

Abstract

The invention relates to an assembly of a flocculation device and a separator device for separating a first liquid substance from a second substance, the two substances forming a mixture, the separator device comprising a vessel with an inlet for receiving the mixture, a first outlet for discharge of a first fraction of the mixture, a second outlet for discharge of a second fraction of the mixture, the second outlet being situated at an upper part of the separator device, the flocculation device comprising an inlet portion with an inlet for raw waste water, a flocculation portion in fluid connection with the inlet portion, the flocculation portion being in fluid connection with the inlet of the vessel for supplying the mixture thereto, wherein the separator device comprises a return duct in fluid connection with the first outlet and in fluid connection with the flocculation device, the inlet or the vessel via a gas mixing device, wherein the gas mixing device is configured for during use introducing a gas mixture comprising air into the return duct to obtain an aerated fluid, characterized in that the flocculation device is in fluid connection with an ozone introduction device for during use introducing ozone into the flocculation device.

Description

ASSEMBLY OF A FLOCCULATION DEVICE, AN OZONE INTRODUCTION DEVICE AND A SEPARATOR DEVICE AND METHOD FOR OPERATING

SUCH AN ASSEMBLY Field of the invention

[0001] The present invention relates to an assembly of a flocculation device and a separator device for separating a first liquid substance from a second substance, the two substances forming a mixture,

the separator device comprising:

a vessel with an inlet for receiving the mixture,

a first outlet for discharge of a first fraction of the mixture,

a second outlet for discharge of a second fraction of the mixture, the second outlet being situated at an upper part of the separator device,

the flocculation device comprising:

an inlet portion with an inlet for raw waste water,

a flocculation portion in fluid connection with the inlet portion, the flocculation portion being in fluid connection with the inlet of the vessel for supplying the mixture thereto,

wherein the separator device comprises a return duct in fluid connection with the first outlet and in fluid connection with the flocculation device, the inlet or the vessel via a gas mixing device, wherein the gas mixing device is configured for during use introducing a gas mixture comprising air into the return duct to obtain an aerated fluid. Background of the invention

[0002] Such an assembly is known from, for example, US 4.156.648. This patent publication describes an assembly of a flocculation device and a separator device for separating a first liquid substance from a second substance in a mixture introduced by the flocculation device in the separator device. Therein, ozone is directly introduced into the vessel by an ozone generator to create a relatively thick foam by oxidizing organic matter in the mixture. Furthermore, the introduction of ozone facilitates disinfection. The foam floats to the surface of the mixture in the vessel and can be scraped off subsequently.

[0003] WO 01/60494 Al generally describes a process for separating a suspended substance in a fluid, in particular by using flotation.

[0004] WO 2009/029381 Al also describes a method and device for separating suspended solids from a fluid. [0005] WO 2005/099857 Al describes a system of plates for use with a dissolved air flotation (DAF) device.

[0006] However, a disadvantage of the known assemblies, in particular the assembly disclosed in US 4.156.648, is that sometimes a relatively large amount of chemicals is needed in the flocculation device to achieve a sufficient degree of coagulation and/or flocculation.

[0007] It is therefore an object of the present invention to provide an assembly of a flocculation device and a separator device, wherein the amount of chemicals required in the flocculation device to achieve a sufficient degree of coagulation and/or flocculation can be reduced. Further objects of the invention are to achieve oxidation and/or to remove unpleasant odours.

Summary of the invention

[0008] Hereto the assembly according to the invention is characterized in that the flocculation device is in fluid connection with an ozone introduction device for during use introducing ozone into the flocculation device.

[0009] The inventors have found that ozone acts as a powerful coagulant (such as for proteins, organic particles), as a result of which the amount of chemicals required in the flocculation device can be reduced. [0010] Furthermore, the ozone aids with dissolving certain fractions in the flocculation device, due to its powerful oxidizing properties. Another advantage is that ozone neutralizes gaseous compounds causing odour. [0011] In the context of this patent application a 'vessel' is to be interpreted in a broad sense and can for instance comprise a tank, pressure vessel, a reservoir, et cetera.

Analogously, a separator device can comprise a Dissolved Air Flotation (DAF) unit, a hydro cyclone separator, a membrane separator, et cetera. [0012] An embodiment relates to an aforementioned assembly wherein the ozone introduction device is formed by the gas mixing device, which during use introduces a gas mixture comprising ozone into the return fluid to obtain an ozonated return fluid. Thus, the return duct and gas mixing device can be advantageously used for supplying ozone to the flocculation device.

[0013] Another embodiment concerns an aforementioned assembly, wherein the flocculation device comprises a coagulation portion, wherein the coagulation portion is in fluid connection with the ozone introduction device for during use introducing ozone into the coagulation portion of flocculation device. By direct injection of ozone in the coagulant portion of the flocculation device, the coagulant effects of the ozone are optimized.

[0014] Therein, the return duct can be in fluid connection with this coagulation portion. [0015] An embodiment relates to an aforementioned assembly, wherein the return duct is furthermore in fluid connection with a lower part of the vessel or the inlet of the vessel.

[0016] Advantageously, the concentration of ozone in the gas mixture is adjusted for the type of water to be treated and the purpose of the treatment.

[0017] Therein, for oxidation purposes the concentration of ozone in the gas mixture can be approximately 1-100%, more preferably 20-100 %, even more preferably 30- 100 %, yet even more preferably 50-100 %, and/or for coagulation and/or odour removal purposes the concentration of ozone in the gas mixture is approximately 0.1 - 100 %, more preferably 1 - 50 %. [0018] It should be noted that the ozone can additionally be introduced in the (first) outlet of the vessel.

[0019] A further embodiment relates to an aforementioned assembly, wherein the vessel comprises a flow element comprising a number of parallel tubular channels defining a flow path for the mixture, the channels having an inlet end for receiving the mixture and an outlet end for discharge of the first fraction, a length direction of the channels being inclined with respect to a horizontal direction, wherein in a transverse cross-section through the flow element, the channels form a two-dimensional array of closed cells, each cell defining a boundary of a flow channel, the cells being arranged in at least two rows, each cell in a first row contacting with its perimeter a cell in the second row, wherein an upper side of the flow channels being in fluid communication with the inlet for forming a flow path for the mixture from the upper to a lower part of flow channels, the second outlet being situated at an upper part of the separator device in fluid communication with the upper part of the flow channels, a flow path for gas and the second fraction of the mixture extending from a lower part to an upper part of the flow channels.

[0020] By forming a two-dimensional array of enclosed flow channels, the channels have a decreased hydraulic diameter, and hence a lower Reynolds number. The small hydraulic diameter allows the Reynolds number of the flow element to remain low during operation which means that laminar flow conditions can be maintained even at high flow rates, while maintaining a favourable upwards rise rate of ozone and/or air bubbles and floatable material entrained by the bubbles through the flow channels. Hence the flow rate can be increased in the separation device while maintaining proper separation. [0021] Due to the increased flow rate provided by the above embodiment, the rate at which ozone oxidizes matter contained in the vessel, and the rate at which ozone removes unwanted smells therefrom is also increased. [0022] Another aspect of the invention relates to a method for operating an

aforementioned assembly, comprising the steps of:

introducing raw waste water into the inlet portion of the flocculation device, allowing coagulation and/or flocculation to occur in the flocculation device, wherein the mixture comprising the first liquid substance and the second substance is formed,

introducing the mixture into the separator device,

discharging the first fraction of the mixture via the first outlet,

discharging the second fraction of the mixture via the second outlet, introducing ozone into the flocculation device with the ozone introduction device.

[0023] According to an embodiment, the aforementioned method further comprises the step of introducing a polymer into the flocculation device to improve its performance. [0024] Another aspect of the invention relates to the use of ozone as a coagulation agent in an aforementioned assembly, wherein the ozone is for instance introduced in the coagulation portion of the flocculation device.

[0025] Again, preferably, the ozone is introduced into the coagulation portion of the flocculation device by using the ozonated fluid of the return duct.

Brief description of the drawings

[0026] Embodiments of an assembly according to the invention will by way of non- limiting example be described in detail with reference to the accompanying drawings. In the drawings: [0027] Figures 1 A and IB show a frontal view and side view, respectively of an assembly of a flocculation device and a separator device according to the present invention. Detailed description of the invention

[0028] Figures 1 A and IB show a frontal view and side view, respectively of an assembly of a flocculation device and a separator device according to the present invention.

[0029] Figure 1 shows a separator device 1, with an inlet 3 for receiving a mixture of substances, such as waste water, from a flocculation device 4. The assembly of the flocculation device 4 and separator device 1 is indicated with reference numeral 6. [0030] The flocculation device 4 comprises an inlet for raw waste water 21 and a subsequent piping system with multiple curves, such as in a zigzag pattern, to achieve proper coagulation/flocculation. The flocculation device 4 comprises a coagulation portion 8, having a coagulant introduction portion, preferably relatively close the inlet 21, for the optional introduction of a coagulant. At the position of the coagulant introduction portion (not shown), the coagulation portion 8 has a pipe diameter that is comparatively small compared to the main part of the flocculation device's 4 piping system, such as 0.6-0.9, preferably approximately 0.8 times. Basically a diameter reduction of approximately 10-20% is aimed for. Downstream of the coagulation portion 8, the flocculation device 4 furthermore comprises a further introduction portion having a polymer introduction portion 23 where a polymer can be introduced. The polymer introduction portion 23 preferably is situated relatively close to the inlet 3 of the separator device 1. Again, its diameter is relatively small compared to the main part of the flocculation device's 4 piping system, such as 0.6-0.9, preferably about 0.9 times that diameter to facilitate proper mixing. It should be noted however that the geometry of the piping system is primarily to be calculated based on required mixing energy. Furthermore, generally less mixing energy is required for flocculation than for coagulation, as otherwise the floes formed during flocculation can be destroyed. Both the coagulant introduction portion 8 as well as the further introduction portion or the polymer introduction portion 23 can be used for introducing coagulant and/or flocculant if desired.

[0031] When entering the separator device 1 from the flocculation device 4, the mixture flows to an inlet end 5 of a flow element 7. The flow element 7 is

schematically indicated in this figure, and comprises a 3-dimensional array of parallel flow channels. The flow channels are oriented at an angle to the horizontal, for instance at a slanting angle of 60°. From an outlet end 9 of the flow element 7, a first fraction of the mixture, such as water, flows through an upwardly extending channel 10 to an outlet 11, and from there to a first outlet 12. The second fraction, such as oil, grease or solids, is collected in compartment 19 and is discharged via a skimmer/scraper 20 through second outlet 13, shown in Figure IB. Heavy debris, such as sand, may be discharged through outlet 14. A return duct 15 is attached to the lower end of channel 10 and is via pump 16 (to pressurize the return fluid) connected to gas mixing device 17. In the gas mixing device 17, according to the invention, a gas mixture comprising ozone can be introduced such that ozonated water is formed, which ozonated water is fed to the flocculation device 4, such as the coagulation portion 8 thereof. A position just downstream of the coagulant introduction portion can advantageously be used for that purpose. The rest of the gas mixture may comprise compressed air.

[0032] Alternatively, the return duct 15 can be designed in such a way that the ozonated fluid is (also) introduced at a position in between the polymer introduction portion 23 of the flocculation device 4 and the inlet 3 of the separator device 1.

Furthermore, a return duct 15 construction is conceivable wherein the ozonated fluid is introduced directly into the vessel 2, for instance at a position below or underneath the inlet 3, e.g. in the same vessel 2 wall where the inlet 3 is arranged. A suitable distributor 18 or valve may be used to facilitate the distribution of ozonated return fluid flow towards these positions. The distributor 18 can for instance be placed in the return duct 15 downstream of the gas mixing device 17. Another possibility is to connect the ozone introduction device 17 in such a way as to introduce ozone in the outlet 11 or first outlet 12. [0033] Upon release of the pressure of the mixture of ozonated water and the substances to be separated at the inlet 3, small ozone and/or air bubbles are formed in the liquid to be separated, entraining floatable matter, which accumulates in the compartment 19 of the separator 1. The mixture of water and floatable matter flows vertically downward from inlet end 5 through the flow element 7, to the outlet end 9. Due to laminar flow, ozone and/or air bubbles rise upward against the flow direction, from the outlet end 9 to inlet end 5, entraining floatable matter upward to compartment 19 to be eventually removed via flotation sludge outlet 22 or first outlet 12. [0034] Thus, the invention has been described by reference to the embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.

Reference numerals

1. Separator device

2. Vessel

3. Inlet of mixture

4. Flocculation device

5. Inlet end of flow element

6. Assembly of flocculation device and separator device

7. Flow element

8. Coagulant portion

9. Outlet end of flow element

10. Upwardly extending channel

11. Outlet

12. First outlet

13. Second outlet

14. Outlet

15. Return duct

16. Pump

17. Gas mixing device

18. Distributor

19. Compartment

20. Scraper/transport belt

21. Raw waste water inlet

22. Outlet for flotation sludge

23. Polymer introduction portion

Claims

1. Assembly (6) of a flocculation device (4) and a separator device (1) for separating a first liquid substance from a second substance, the two substances forming a mixture,

the separator device (1) comprising:

a vessel (2) with an inlet (3) for receiving the mixture,

a first outlet (12) for discharge of a first fraction of the mixture,

a second outlet (13) for discharge of a second fraction of the mixture, the second outlet (13) being situated at an upper part of the separator device,

the flocculation device (4) comprising:

an inlet portion with an inlet (21) for raw waste water,

a flocculation portion in fluid connection with the inlet portion, the flocculation portion being in fluid connection with the inlet (3) of the vessel (2) for supplying the mixture thereto,

wherein the separator device (1) comprises a return duct (15) in fluid connection with the first outlet (12) and in fluid connection with the flocculation device (4), the inlet (3) or the vessel (2) via a gas mixing device (17), wherein the gas mixing device (17) is configured for during use introducing a gas mixture comprising air into the return duct (15) to obtain an aerated fluid,

characterized in that the flocculation device (4) is in fluid connection with an ozone introduction device for during use introducing ozone into the flocculation device (4).

2. Assembly (6) according to claim 1, wherein the ozone introduction device is formed by the gas mixing device (17), which during use introduces a gas mixture comprising ozone into the return fluid to obtain an ozonated return fluid.

3. Assembly (6) according to claim 1 or 2, wherein the flocculation device comprises a coagulation portion (8), wherein the coagulation portion is in fluid connection with the ozone introduction device for during use introducing ozone into the coagulation portion of the flocculation device (4).

4. Assembly (6) according to claim 3, wherein the return duct (15) is in fluid connection with the coagulation portion.

5. Assembly (6) according to any one of the preceding claims, wherein the return duct is in fluid connection with a lower part of the vessel or the inlet (3) of the vessel.

6. Assembly (6) according to any one of the preceding claims, wherein the concentration of ozone in the gas mixture is adjusted for the type of water to be treated and the purpose of the treatment.

7. Assembly (6) according to claim 6, wherein for oxidation purposes the concentration of ozone in the gas mixture is approximately 1-100%, more preferably 20-100 %, even more preferably 30-100 %, yet even more preferably 50-100 %, and/or for coagulation and/or odour removal purposes the concentration of ozone in the gas mixture is approximately 0.1 - 100 %, more preferably 1 - 50 %.

8. Assembly (6) according to any one of the preceding claims, wherein the ozone is introduced in the first outlet (12) of the vessel.

9. Assembly according to any one of the preceding claims, wherein the vessel (2) comprises a flow element (7) comprising a number of parallel tubular channels defining a flow path for the mixture, the channels having an inlet end (8) for receiving the mixture and an outlet end (9) for discharge of the first fraction, a length direction of the channels being inclined with respect to a horizontal direction, wherein in a transverse cross-section through the flow element, the channels form a two-dimensional array of closed cells (22), each cell defining a boundary of a flow channel, the cells being arranged in at least two rows, each cell in a first row contacting with its perimeter a cell in the second row, wherein an upper side of the flow channels being in fluid

communication with the inlet (3) for forming a flow path for the mixture from the upper to a lower part of flow channels, the second outlet (13) being situated at an upper part of the separator device in fluid communication with the upper part of the flow channels, a flow path for gas and the second fraction of the mixture extending from a lower part to an upper part of the flow channels.

10. Method for operating an assembly according to any one of the preceding claims, comprising the steps of:

introducing the mixture into the separator device,

discharging the first fraction of the mixture via the first outlet,

discharging the second fraction of the mixture via the second outlet,

- introducing ozone into the flocculation device with the ozone introduction device.

11. Method according to claim 10, further comprising the step of introducing a polymer into the flocculation device (4).

12. Use of ozone as a coagulation agent in an assembly (6) according to any one of the claims 1-9, wherein the ozone is for instance introduced in the coagulation portion (8) of the flocculation device.

13. Use of ozone according to claim 12, wherein the ozone is introduced into the coagulation portion of the flocculation device, for instance by using the ozonated fluid of the return duct.