PLANT FOR THE PURIFICATION OF WASTE AND/OR PROCESS WATER BY MEANS OF ANAEROBIC MICROORGANISMS WITH A REACTOR TANK AND AN EXTERNAL SEPARATION APPARATUS

Abstract

A plant for the anaerobic purification of waste and/or process water comprising: i) a reactor tank with at least one feed line for supplying waste and/or process water into tank and with at least one outflow line for draining a mixture of microorganisms, waste and/or process water and gas from the tank, ii) a first separation apparatus outside and downstream of the tank for separating at least a part of the microorganisms from the mixture from the tank, wherein the first separation apparatus comprises at least one separation stage, an inlet line connected with at least one of the outflow line(s), at least one discharge line and at least one outlet line, and iii) a return line for returning the separated sludge separated into the reactor tank, wherein the return line connects with at least one of the at least one outlet line of the first separation apparatus.

Claims

1. A plant (10) for the purification of waste and/or process water by means of anaerobic microorganisms (22), wherein the plant (10) comprises: i) a reactor tank (12) for the anaerobic purification of waste and/or process water with at least one feed line (20) for supplying waste and/or process water to be purified into the reactor tank (12) as well as with at least one outflow line (28) for draining a mixture of anaerobic microorganisms (22), waste and/or process water and gas from the reactor tank (12), ii) a first separation apparatus (14) arranged outside and downstream of the reactor tank (12) for separating at least a part of the anaerobic microorganisms (22) in form of sludge from the mixture drained from the reactor tank (12), wherein the first separation apparatus (14) comprises at least one separation stage (30), an inlet line (32) being connected with at least one of the at least one outflow line (28) of the reactor tank (12), at least one discharge line (36) and at least one outlet line (34), and iii) a return line (18) for returning the sludge separated in the first separation apparatus (14) into the reactor tank (12), wherein the return line (18) is connected with at least one of the at least one outlet line (34) of the first separation apparatus (14) wherein the first separation apparatus for separating the anaerobic microorganism from the purified water and the gas can be maintained without necessarily terminating the operation of the reactor tank and at least without discharging the reactor tank.

2. The plant (10) according to claim 1, wherein the first separation apparatus (14) comprises as separation stage(s) one or more centrifugal separators and/or one or more lamella-separators.

3. The plant (10) according to claim 2, wherein the first separation apparatus (14) comprises as separation stage(s) one or more cyclones (30).

4. The plant (10) according to claim 1, wherein the first separation apparatus (14) is in the plant (10) lower than the upper end of that outflow line (28) of the reactor tank (12), with which the inlet line (32) of the first separation apparatus (14) is connected, so that the mixture drained from the reactor tank (12) flows gravity driven from that outflow line (28) of the reactor tank (12) into the inlet line (32) of the first separation apparatus (14).

5. The plant (10) according to claim 1, wherein the first separation apparatus (14) comprises one cyclone (30), wherein the cyclone (30) is connected with the inlet line (32), with one of the at least one outlet line (34) and further with one of the at least one discharge line (36) for discharging from the cyclone (30) a mixture of anaerobic microorganisms (22), waste and/or process water and gas, which is depleted in the content of anaerobic microorganisms (22) compared with the mixture drained from the reactor tank (12), wherein the outlet line (34) to which the first cyclone (30) is connected, is connected with the return line (18).

6. The plant (10) according to claim 1, wherein the first separation apparatus (14) comprises two cyclones (30), wherein the first of the two cyclones (30) is connected with the inlet line (32), with one of the at least one outlet line (34) and further with one of the at least one discharge line (36) for discharging from the first cyclone (30) a mixture of anaerobic microorganisms (22), waste and/or process water and gas, which is depleted in the content of anaerobic microorganisms (22) compared with the mixture drained from the reactor tank (12), and wherein the second of the two cyclones is connected with the discharge line (36) from the first cyclone (30), with another one of the at least one outlet line and further with another one of the at least one discharge line for discharging from the second cyclone a mixture of anaerobic microorganisms (22), waste and/or process water and gas, which is depleted in the content of anaerobic microorganisms (22) compared with the mixture drained from the first cyclone (30), wherein the outlet line (34) to which the first cyclone (30) is connected and the outlet line to which the second cyclone is connected, are connected with the return line (18).

7. The plant (10) according to claim 1, which further comprises a second, three-phase separation apparatus (16) arranged downstream of the first separation apparatus (14) for separating the mixture withdrawn from the discharge line (36) of the first separation apparatus (14) into a gas-rich phase, into a water-rich phase and into a sludge-rich phase, wherein the second, three-phase separation apparatus (16) comprises at least one separation stage (38), an inlet line (42) being connected with the discharge line (36) of the first separation apparatus (14), at least one gas outlet line (44), at least one water outlet line (46) and at least one sludge outlet line (48), wherein the at least one sludge outlet line (48) is connected with the return line (18).

8. The plant (10) according to claim 7, wherein the second, three-phase separation apparatus (16) comprises as separation stage(s) one or more lamella-separators (38).

9. The plant (10) according to claim 7, wherein the second, three-phase separation apparatus (16) comprises one lamella-separator (38), wherein the lamella-separator (38) is connected with the inlet line (42), wherein the lamella-separator (38) comprises a gas outlet line (44), a water outlet line (46) and a sludge outlet line (48), wherein the sludge outlet line (48) is connected with the return line (18).

10. The plant (10) according to claim 7, wherein the second, three-phase separation apparatus (16) comprises two lamella-separators (38), wherein the first of the two lamella-separators (38) is connected with the inlet line (42), wherein the first lamella-separator (38) comprises a gas outlet line (44), a water outlet line (46) and a sludge outlet line (48), and wherein the second of the two lamella-separators is connected with the water outlet line (46) from the first lamella-separator (38) and further comprises a gas outlet line, a water outlet line and a sludge outlet line, wherein the sludge outlet line (48) of the first lamella-separator (38) and the sludge outlet line of the second lamella-separator are connected with the return line (18).

11. The plant (10) according to claim 1, wherein the return line (18) comprises a storage container (50) to even changes of flow stream through the first separation apparatus (14) to ensure a constant fluid flow returned via the return line (18) into the reactor tank (12).

12. The plant (10) according to claim 1, wherein the reactor tank (12) comprises one or more overflows (26), wherein each of which is connected with one of the at least one outflow line (28) for draining a mixture of anaerobic microorganisms (22), waste and/or process water and gas from the reactor tank (12).

13. The plant (10) according to claim 12, wherein each of the one or more overflows (22) comprises at least two vertically arranged or sloped lamellae (40), wherein all lamellae (40) are arranged in parallel with each other to define flow paths there between, so that the separation of gas from the waste and/or process water is facilitated.

14. The plant (10) according to claim 1, wherein the upper part of the reactor tank (12) is conically so that gas may be collected there.

15. The plant (10) according to claim 1, wherein the reactor tank (12) does not comprise any gas hood and/or any other separation means for keeping the biomass in the reactor tank (12).

16. The plant (10) according to claim 1, wherein the reactor tank (12) comprises a mixer (24) for improving the mixing of the waste and/or process water and the microorganism (22).

17. A plant (10) for the purification of waste and/or process water by means of anaerobic microorganisms (22), wherein the plant (10) comprises: i) a reactor tank (12) for the anaerobic purification of waste and/or process water with at least one feed line (20) for supplying waste and/or process water to be purified into the reactor tank (12) as well as with at least one outflow line (28) for draining a mixture of anaerobic microorganisms (22), waste and/or process water and gas from the reactor tank (12), ii) a first separation apparatus (14) arranged outside and downstream of the reactor tank (12) for separating at least a part of the anaerobic microorganisms (22) in form of sludge from the mixture drained from the reactor tank (12), wherein the first separation apparatus (14) comprises at least one separation stage (30), an inlet line (32) being connected with at least one of the at least one outflow line (28) of the reactor tank (12), at least one discharge line (36) and at least one outlet line (34), wherein the first separation apparatus (14) comprises as separation stage(s) one or more cyclones (30), and iii) a return line (18) for returning the sludge separated in the first separation apparatus (14) into the reactor tank (12), wherein the return line (18) is connected with at least one of the at least one outlet line (34) of the first separation apparatus (14).

18. The plant (10) according to claim 17, wherein the reactor tank (12) does not comprise any gas hood and/or any other separation means for keeping the biomass in the reactor tank (12).

19. A method for purifying waste and/or process water by means of anaerobic microorganisms (22), which comprises the steps of: a) feeding waste and/or process water into a reactor tank (12) of a plant (10) via at least one feed line (20), b) draining a mixture of anaerobic microorganisms (22), waste and/or process water and gas from the reactor tank (12) and leading it into a first separation apparatus (14) and c) returning sludge separated in the first separation apparatus (14) into the reactor tank (12) via a return line (18) wherein the first separation apparatus for separating the anaerobic microorganism from the purified water and the gas can be maintained without necessarily terminating the operation of the reactor tank and at least without discharging the reactor tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] There is shown:

[0058] FIG. 1 a schematic longitudinal sectional view of a plant for the purification of influent water by means of anaerobic microorganisms in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0059] The plant 10 for purifying waste and/or process water by means of anaerobic microorganisms comprises a reactor tank 12 for the anaerobic purification of waste and/or process water, a first separation apparatus 14 arranged outside and downstream of the reactor tank 12 for separating at least a part of the anaerobic microorganisms in form of sludge from the mixture drained from the reactor tank 12, a second three-phase separation apparatus 16 arranged outside the reactor tank and downstream of the first separation apparatus 14 for separating the sludge-depleted mixture withdrawn from the first separation apparatus 14 into a gas-rich phase, into a water-rich phase and into a sludge-rich phase as well as a return line 18 for returning the sludge separated in the first separation apparatus 14 and in the second separation apparatus 16 into the reactor tank 12.

[0060] More specifically, the reactor tank 12 shown schematically in longitudinal section in FIG. 1 is made cylindrical in its lower and middle part and converges upwardly in a conical form in its upper part. The reactor tank 12 comprises one feed line 20, through which waste and/or process water to be purified is supplied into the reactor tank 12. The reactor tank 12 is filled until the lower end of the conical upper part with a mixture of anaerobic bacteria 22, with waste and/or process water and biogas generated by the anaerobic bacteria 22 during the operation of the plant 10. In the lower part, a mixer 24 is provided for homogeneously mixing the three phases. At the upper part of the reactor tank, an overflow 26 is provided, which is connected with an outflow line 28. During the operation of the plant continuously a part of the three-phase mixture is drained from the reactor tank 12 through the overflow 26 and outflow line 28. Furthermore, the reactor tank 12 comprises on its top a gas outlet line 29 for discharging a part of the gas generated by the anaerobic microorganism during the operation. In contrast to the reactors known from the prior art, no gas hoods or other separations devices are provided in the reactor tank.

[0061] Outside and downstream of the reactor tank 12, the first separation apparatus 14 for separating at least a part of the anaerobic microorganisms in form of sludge from the mixture drained from the reactor tank 12 is arranged, wherein the first separation apparatus 14 comprises one cyclone 30 as separation stage. The cyclone 30 is connected through an inlet line 32 with the outflow line 28 and thus with the reactor tank 12 and is further connected with an outlet line 34 for discharging a microorganism rich sludge fraction from the cyclone. The outlet line 34 is connected with the return line 18. In addition, the cyclone 30 is provided with a discharge line 36 for discharging from the cyclone a mixture of anaerobic microorganisms, waste and/or process water and gas, which is depleted in the content of anaerobic microorganisms compared with the mixture drained from the reactor tank 12.

[0062] As an alternative to the shown cyclone 30, the first separation apparatus 14 may comprise one or more lamella-separators instead of the cyclone 30 or in addition to the cyclone 30.

[0063] The second, three-phase separation apparatus 16, which is arranged outside the reactor tank and downstream of the first separation apparatus 14, comprises one lamella-separator 38 including several lamellae, wherein the lamella-separator 38 provides an inlet line 42, which is connected with the discharge line 36. Moreover, the lamella-separator 38 comprises a gas outlet line 44, a water outlet line 46 and a sludge outlet line 48. In turn, the sludge outlet line 48 is connected with the return line 18, wherein the return line 18 comprises a storage container 50.

[0064] During the operation of the plant 10, waste and/or process water to be purified is continuously supplied through the feed line 20 into the reactor tank 12 so that the reactor tank 12 is filled during the operation of the plant 10 until the lower end of the conical upper part with a mixture of anaerobic bacteria 22, with waste and/or process water and biogas generated by the anaerobic bacteria 22 during the operation of the plant 10. This mixture is homogeneously mixed by the mixer 24 provided in the lower part of the reactor tank 12. The anaerobic bacteria 22 degrade the organic contaminants contained in the waste and/or process water primarily to carbon dioxide and methane, which are dissolved and/or dispersed in the three-phase mixture. Some of the gas bubbles out of the mixture and collects in the upper conical part of the reactor tank 12 and is continuously discharged via the gas outlet line 29. Likewise, three-phase mixture of anaerobic bacteria 22, water and biogas is continuously discharged via the overflow 26 and the outflow line 28 and fed via the inlet line 32 into the cyclone 30 of the first separation apparatus.

[0065] In the cyclone 30, the three-phase mixture is separated into a microorganism depleted phase and into a microorganism enriched sludge phase, wherein the microorganism depleted phase is discharged from the cyclone 30 via the discharge line 36 and wherein the microorganism enriched sludge phase is discharged from the cyclone 30 via the outlet line 34.

[0066] The microorganism depleted phase is then fed via the inlet line 42 into the lamellae 40 containing lamella-separator 38 of the second three-phase separation apparatus 16. Therein, the mixture is separated into the three phases gas, water and sludge, wherein the gas is discharged via the gas outlet line 44, water is discharged via the water outlet line 46 and sludge is discharged via the sludge outlet line 48.

[0067] The sludge discharged from the first separation apparatus 14 and the sludge discharged from the second three-phase separation apparatus 16 are fed via the return line 18 back into the reactor tank 12. In this context, the storage container 50 assures that the sludge is evenly returned with a constant fluid flow into the reactor tank 12.

REFERENCE NUMERAL LIST

[0068] 10 Plant [0069] 12 Reactor tank [0070] 14 First separation apparatus [0071] 16 Second (three-phase separation) apparatus [0072] 18 Return line [0073] 20 Feed line [0074] 22 Anaerobic bacteria/Microorganism [0075] 24 Mixer [0076] 26 Overflow [0077] 28 Outflow line [0078] 29 Gas outlet line [0079] 30 Cyclone/Separation stage [0080] 32 Inlet line [0081] 34 Outlet line [0082] 36 Discharge line [0083] 38 Lamella-separator/Separation stage [0084] 40 Lamellae [0085] 42 Inlet line [0086] 44 Gas outlet line [0087] 46 Water outlet line [0088] 48 Sludge outlet line [0089] 50 Storage container