EP1678089A1

EP1678089A1 - Reactor and method for anaerobic wastewater treatment

Info

Publication number: EP1678089A1
Application number: EP04791056A
Authority: EP
Inventors: Walter Herding; Urs Herding; Kurt Palz; Rainer THÜRAUF; Stephan Prechtl; Rainer Scholz; Ralf Schneider; Johann Winter; Rolf Jung
Original assignee: Atz-Evus Entwicklungszentrum fur Verfahrenstechnik; Herding GmbH Filtertechnik
Current assignee: Atz-Evus Entwicklungszentrum fur Verfahrenstechnik; Herding GmbH Filtertechnik
Priority date: 2003-10-29
Filing date: 2004-10-29
Publication date: 2006-07-12
Also published as: US7485228B2; RU2377191C2; JP2007506542A; RU2006118344A; US20070251880A1; WO2005042418A1; DE10350502B3; CN100447099C; CN1874964A; JP3989524B2

Abstract

The invention relates to a reactor (10), for anaerobic wastewater treatment, embodied as a loop reactor with a central flow channel (20). Support elements (50), for the immobilisation of micro-organisms, are placed in the annular area (40) between the central flow channel (20) and the reactor wall, flow paths being formed between adjacent support elements (50). The lower section of the reactor (30), located under the support elements, is embodied as a chamber, provided for receiving wastewater with the micro-organisms floating therein, on operation of said reactor (10). On operation, floating micro-organisms as well as micro-organisms, immobilised on the support elements, are provided. The wastewater to be treated flows downwards in the centre and returns upwards along the support elements (40), the current being partially generated by gas evolution from the micro-organisms. A method for anaerobic wastewater treatment is carried out by means of said reactor which is suitable for wastewater treatment in the food and feedstuffs industry and in the paper and textile industry.

Description

Anaerobic wastewater treatment reactor and process

This invention relates to a reactor and a method for anaerobic wastewater treatment.

For the treatment of organically polluted wastewater, it is known to use anaerobic processes or anaerobic wastewater treatment systems. When using anaerobic technology, the dirt load contained in the wastewater is converted into the regenerative energy source biogas with the help of appropriate microorganisms, which enables savings in energy consumption. The processes used for this include both simple processes without biomass enrichment and high-performance processes with usually internal biomass enrichment.

Municipal wastewater is comparatively low contaminated with a chemical oxygen demand (COD) of approx. 500 mg / l and is usually treated with aerobic activated sludge processes. In the food industry there are significantly higher organically contaminated wastewater with COD of over 1,000 and up to 100,000 mg / l and more. High-performance processes are used to purify such waste water.

The most common method is the so-called UASB (Upflow Anaerobic Sludge Blanket) method. An internal biomass enrichment takes place in UASB reactors in the form of a developing and very well granulating sludge. The microorganisms aggregate into so-called pellets. These are aggregates with a size of approx. 1 to 3 mm. The reactors are operated in upflow mode, ie the waste water flows through the reactor from bottom to top. The metabolic degradation of organic contaminants creates gases that adhere to the pellets in the form of gas bubbles. As a result, the pellets rise which leads to mixing in the system. A separator system is provided in the upper area of the UASB reactor, which serves to retain the pellets in the reactor. An advantage of these reactors is that they can have a relatively simple construction, for example as a loop reactor. Such a reactor is described in DE 43 33 176. A disadvantage of this technique is that at high COD concentrations from about 20 to 30 g / l the gas evolution becomes so strong that the pellets rise very quickly and that despite the separator systems there is a considerable loss of biomass. This is called the "wash-out effect". In addition, these systems are relatively sensitive to poisoning (a so-called toxic shock). These systems can be started up relatively quickly after an accident in the reactor by inoculating again with new biomass, but this is a cost factor. Another disadvantage of this method is that only microorganisms which form pellets can be used severely limits the selection of microorganisms. As a rule, methanogenic bacteria are mainly used in the genus Methanotrix.

Another high-performance process uses fixed bed reactors, whereby inert carrier materials as beds, packs or also fixed carrier materials, e.g. in the form of plate-shaped carrier elements, colonized by microorganisms. Such a reactor is described in patent DE 43 09 779 by the same applicant. Very heavily polluted wastewater with COD concentrations of over 80 g / l can be treated in fixed bed reactors. A disadvantage of the fixed bed reactor is that the costs are high, especially in the case of high-performance carrier materials.

In addition, fluidized bed reactors are also known in which the biomass is immobilized on a fluidized fixed bed, for example activated carbon or sand, which is swirled in the reactor. This requires a high energy requirement to maintain the fluidized bed, which also results in a high load on the reactors. The design of fluidized bed reactors is accordingly technically demanding and complex. The invention has for its object to provide a reactor and a method for anaerobic wastewater treatment, which is suitable for heavily polluted wastewater and works with little interference and is comparatively inexpensive.

This object is achieved by a reactor for anaerobic wastewater treatment, which has the following features:

(a) a central flow channel leading from top to bottom, which ends at the top with a first distance from the upper reactor limit and ends at the bottom with a second distance from the lower reactor limit; (b) In the annular space between the central flow channel and the reactor wall, support elements for immobilizing microorganisms in the form of a structured, ordered fixed bed are positioned for the entire height of the flow channel or for part of the height of the flow channel, flow paths being present between adjacent support elements are; (c) a lower region of the reactor between its lower boundary and the support elements is designed as a space which is intended to receive waste water with microorganisms suspended in it when the reactor is in operation; (d) an upper region of the reactor between its upper boundary and the support elements; (e) the reactor is designed in terms of its internal flow as a loop reactor such that the waste water contained can be circulated down through the central flow channel, then through the space in the lower region, then up along the support elements, and finally back into the central flow channel , (f) a feed line for waste water to be treated which is to be introduced into the reactor for the first time; (g) an exhaust system for the final discharge of treated wastewater from the reactor. The invention provides a hybrid reactor (or a hybrid process) which (or which) combines the advantages of fixed bed reactors and UASB reactors 105.

The reactor can be cylindrical, other reactor geometries are also possible, e.g. cylindrical arrangements with an elliptical or polygonal base or cuboid arrangements.

110 The room in the lower area can hold waste water with microorganism pellets suspended in it. The microorganisms develop metabolic gases that adhere to the pellets as bubbles and thereby carry the pellets upwards. Bacteria of the Gat- are preferred as microorganisms

115 tung Methanotrix used.

A separator system is preferably arranged in the upper area, which retains microorganisms suspended in the waste water in the reactor.

Furthermore, the reactor preferably has a recirculation system, which has an extractor for waste water and a feeder for waste water for discharging the flow into the central flow channel.

The extractor preferably comprises a gap between two plattenar- 125 ^• term elements and a beginning in the intermediate space conduit has. ,

It is particularly preferred that the discharge system for the final discharge of treated wastewater is positioned a little above the extractor of the recirculation system.

130 microorganism pellets, which rise in the upper area of the reactor, are retained by the separator system, release the adhering gas bubbles and, due to their greater density, sink back down. The sepaprator system can be used to separate the gases 135 generated as well as to retain the biomass. The separator system preferably has a partition wall at a distance above the upper end of the central flow channel, which covers a large part of the reactor cross section and leaves an outer annular surface free.

140 The extractor of the recirculation system is preferably positioned on the top of the partition. In the space above the tapping point of the recirculation system, a flow-calmed zone is created that supports the discharge of treated waste water without biomass discharge, especially since - as mentioned above - it is preferred that the discharge system for the final discharge of treated waste water is one piece is positioned above the extractor of the recirculation system.

It is emphasized that the described recirculation system and the described separation of the extractor of the recirculation system and the extraction system on the one hand represent a preferred development of the disclosed invention, but on the other hand also technically feasible without the features (or only with some of the features) of claim 1 are. A typical example is the implementation in a UASB reactor which is not a hybrid 155 reactor in the sense of the present application.

The partition of the separator system preferably runs in some areas non-horizontally and forms a gas collection space in a highest area.

160 Furthermore, it is preferred that the partition wall - roughly speaking - runs obliquely outwards downwards and obliquely inwards downwards.

A first discharge line 165 for gas formed in the reactor preferably begins in the upper region of the reactor.

It is further preferred that a second discharge line for gas formed in the reactor begins in the area of the partition. 170 Support elements are provided in the reactor. The carrier elements can be designed in the form of plates. The carrier elements are preferably arranged parallel to one another. The plates can be arranged in packages, the plates being arranged within the packages in the tangential direction of the reactor. The support elements are arranged above the space in the lower area, 175 so that the pellets floating upward flow between the plates. During the operation of the reactor, microorganism growth forms on the support elements. It is preferred that there is a distance of 3-6 cm, preferably 3.5-5.5 cm, between the carrier elements.

180 The carrier elements can consist of an inert material with a large surface. They preferably consist of a flow-porous material. The carrier elements particularly preferably consist essentially of plastic particles and expanded clay particles combined with one another. Polyethylene particles are preferred, with other plastics being possible. The micro or

185 gansimes can settle in the pores of the expanded clay and in the pores between the particles and form a film-like or lawn-like growth on the carrier elements. In the event of a reactor breakdown, e.g. due to a toxic impact, the microorganism film is destroyed. However, the microorganisms can quickly get out of the pores of the porous carrier material

190 grow again and regenerate the film on the plates. The plates of the support elements can be coated with a variety of microorganisms, e.g. Bacteria to be colonized. It is possible to populate the carrier elements with different species at the same time. The carrier elements can be populated with the same species as free floating aggregates or pellets

195 forms. Likewise, the carrier elements can be populated with other species than those which form or form the pellets. This allows the advantages of the UASB method to be combined with the advantage of a greater variety of usable microorganisms.

200 The carrier elements can be populated with sessile microorganisms. In particular, they can be populated with the genera Sytrophobacter, Sytrophomas, Methanotrix, Methanosarcina and Methanococcus. The inventors have found that the synergy effects (high performance 205 with stable operation) from the combination of a fixed bed reactor and a UASB reactor already occur with a relatively small proportion of carrier plates based on the reactor volume. It is therefore preferred that the proportion of the reactor volume covered with carrier plates is 15 to 40%. The proportion is particularly preferably 20 to 30%. 210 A flow deflector is preferably positioned on the wall in the lower region of the reactor. This flow deflector has the task of releasing the wastewater flow from the reactor wall and directing it to the carrier elements in a more uniform manner.

215 The reactor can preferably have at least one propulsion jet outlet which ends below the lower end of the central flow channel. This serves to whirl up microorganisms that have settled on the reactor floor. The mouth can have a nozzle at its end

220 The object of the invention is further achieved by a method for anaerobic wastewater treatment in a reactor in which wastewater to be treated circulates, such that wastewater

225 (a) flows centrally from top to bottom;

(b) is then in contact with microorganisms suspended in the waste water in a space in the lower region of the reactor;

230 (c) then flows in an overhead space of the reactor along microorganisms which are arranged in the form of a structured ordered fixed bed on support elements;

(d) and finally merges again into the central flow from top to bottom 235. After discharge flow on the microorganisms on the carrier elements, part of the waste water is preferably branched off and pumped into the central flow channel. This improves circulating wastewater recirculation.

In the method according to the invention, the microorganisms floating in the treatment room are preferably present in the form of pellets. The in

245 microorganisms suspended in wastewater are retained by a separator system. In the method, different types of microorganisms can be provided as microorganisms immobilized on the carrier elements on the one hand and as floating microorganisms on the other hand. Different species of microorganisms can be found on the carrier elements

250 may be provided.

The reactor and process of the present invention can be used to treat waste water, particularly anaerobic treatment of waste water.

255 According to the invention, in particular organically contaminated wastewater from the beverage, feed or food industry is treated, such as wastewater from starch-processing plants and plants, beverage companies, breweries, spirits distilleries, dairies, wastewater from meat and 260 fish-processing companies. The process according to the invention and the reactor are also suitable for treating waste water from the paper and textile industry.

An embodiment of the invention is shown below by way of example with reference to the drawings.

Fig. 1 is a schematic representation of an embodiment of the reactor for waste water treatment according to the invention.

270 FIG. 2A is a schematic illustration of an embodiment of a waste water extractor of the reactor according to the invention.

2B is a schematic representation of an alternative embodiment of a wastewater extractor of the reactor according to the invention.

275 FIG. 2C is a schematic illustration of a further alternative embodiment of a wastewater extractor of the reactor according to the invention.

2D is a schematic illustration of an extraction system of the reactor according to the invention.

An embodiment of the reactor according to the invention was constructed and used for the treatment of waste water in a brewery.

285 The schematic structure of the reactor 10 is shown in FIG. 1. The reactor is designed as a loop reactor. The dimensions of the cylindrical reactor are designed so that the height is between 2.0 and 5.0 m and that the diameter is between 1.5 and 2.5 m. The amount of waste water to be treated is between 10 and 20 m ³ / d. The dimensions of the other reactor

290 components in relation to the overall dimensions can be seen from FIG. 1. This reactor is for trial operation. Technical designs for large-scale reactors have significantly larger dimensions, e.g. 5 to 9 m in diameter and 8 to 12 m in height. Other reactor geometries are also possible, e.g. cylindrical arrangements with elliptical or

295 polygonal base or cuboid arrangements. The reactor housing 1 1 is, as is known from the prior art, essentially made of stainless steel sheets. In the reactor 10, a central tube 20 is formed in the axial direction, which begins a piece from the upper end of the reactor and opens into the lower region 30. The central tube 20 is hexagonal in cross section. This hexagonal shape is inexpensive to manufacture and packages with carrier elements 50 can be arranged to match the hexagonal shape. Other geometries are also possible, for example circular or polygonal with a different number of corners. The lower region 30 is designed as a space in which the floating microorganisms are present during operation. Above the lower region 30 there is a central region 40, in which plate-shaped carrier elements 50 are arranged in parallel, so that flow paths in the vertical direction are present between these carrier elements. This arrangement of the carrier elements serves as a fixed bed for the settlement of microorganisms.

The carrier elements are flow-porous and made of a material which is essentially formed from plastic and expanded clay particles combined with one another. Such a material is described in the aforementioned patent DE 43 09 779 by the same applicant.

The plates preferably have a distance of 3 to 6 cm, in particular a distance of 3.5 to 5.5 cm is preferred. The carrier elements, viewed in the top view of the reactor cross section, are arranged tangentially in packages which form hexagon segments. Other arrangements are also conceivable, e.g. Arrangements of rectangular packages, packages with the basic shape of a polygon or arrangements with curved plates.

In order to ensure sufficient biomass retention, a separator system 90 is arranged in the reactor, which is formed from inclined guide elements 91, 92, 93, 94. These guide elements prevent the discharge of solid particles, for example gas-laden pellets. Other arrangements of the line elements are conceivable. The guide elements 91, 92, 93, 94 can the top view be modeled on the hexagonal or polygonal fixed bed shape or be round.

The flow guidance can be seen from the arrows k, I, m, n, o, p, q and r. The wastewater to be treated is essentially supplied via the feed line 60 and draws in liquid from the outer space 40 and flows during operation through the central pipe 20 into the lower region 30, where floating microorganisms are present in the form of pellets. A partial flow is optionally supplied via the pipe 80 and additionally mixes the lower part of the reactor 30. A flow obstacle 120 which runs around the inner reactor wall and is arranged in the lower region 30 of the reactor serves to separate the flow, and the waste water to be treated cannot be preferred Flow on the container wall. The microorganisms used belong to the genus Methanotrix. Due to their metabolism, these bacteria form gases, which adhere to the pellets in the form of small bubbles. As a result, the pellets rise and generate an additional flow of waste water. The wastewater to be treated is guided past the microorganisms on the carrier elements and brought into contact with them. The pellets are retained on a dividing wall formed by guide elements 91, 92, 93, release the gas bubbles due to the agitation occurring on the guide elements and can then return to the lower region through the central pipe 20 due to their higher density than the waste water 30 drop. The partition wall forms a gas collection space 96, in which gas collects and can be discharged via a first gas discharge line 98.

This dividing wall formed from the guide elements 91, 92, 93 covers the majority of the reactor cross section and leaves an annular surface free between its outer edge and the reactor wall. Part of the flow along the support elements is branched off at the outer edge of the partition wall, 91, 92, 93, and is drawn off from the upper region above the partition wall 91, 92, 93 and below the guide elements 94 by a wastewater extractor 100, 101 and via a recirculation system 130 recirculated to the reactor. The guide elements 94 form a calming zone in the upper region of the reactor above the 365 partition 91, 92, 93 and above the extractor of the recirculation system, from which waste water treated via an exhaust system 70 can be removed from the reactor.

The resulting gases can be removed via a second gas discharge line 110 at the upper 370 end of the reactor.

Preferred taps of the recirculation system are shown in Figures 2A, 2B and 2C.

375 Fig. 2A shows the so-called double plate deduction. It consists of two circular plates, one above the other, 40 to 70 mm apart, between which the liquid is drawn off centrally. This arrangement ensures peeling at slow flow speed on the outer periphery of the plates.

380 A ring line with holes is shown in FIG. 2B. In order to ensure an even removal of liquid, the holes, as shown in FIG. 2, are designed with different sizes.

385 A star-shaped pipe outlet is shown in FIG. 2 C, as a result of which the liquid is withdrawn at six points. If the pipe ends are provided with T-pieces (shown with a broken line), the liquid can be drawn off at 12 points.

390 In FIG. 2D, a fume cupboard system with a submerged flume with flue holes is shown. The size and number of holes are selected so that the treated waste water is evenly discharged.

395 The amount of circulating water required for the supply line at 60 is taken via the recirculation system 130. Waste water to be fed to the reactor for the first time can be introduced into the system via line 132. When loading may, or at periodic intervals, a portion of the incoming or circulating wastewater is directed via the pipe 80 as a driving jet into the lower region of the reactor in order to whirl up the biomass (the microorganism pellets) present there. In the case of larger reactors, several propulsion jet orifices can be provided in order to stir up the biomass.

Claims

PATENT CLAIMS 405

1. An anaerobic wastewater treatment reactor, comprising the following features: (a) a central flow channel leading from top to bottom, which ends 410 at a first distance from the upper reactor limit and ends at a second distance from the lower reactor limit; (b) in the annulus between the central flow channel and the reactor wall are for the entire height of the flow channel or for

415 positions part of the height of the flow channel support elements for immobilizing microorganisms in the form of a structured, ordered fixed bed, flow paths being present between adjacent support elements; (c) a lower region of the reactor between its lower boundary 420 and the support elements is designed as a space which is intended to receive waste water with microorganisms suspended therein when the reactor is in operation; (d) an upper region of the reactor between its upper boundary and the support elements;

425 (e) the reactor is designed in terms of its internal flow as a loop reactor such that the waste water contained is circulated downward through the central flow channel, then through the space in the lower region, then upward along the support elements, and finally back into the central flow channel can.

430 (f) a feed line for waste water to be treated which is to be introduced into the reactor for the first time; (g) an exhaust system for the final discharge of treated wastewater from the reactor.

435

2. Reactor according to claim 1, characterized in that the space in the lower area is intended to contain wastewater with ^' microorganism pellets floating therein.

3. Reactor according to claim 1 or 2, characterized in that plate-shaped support elements are provided.

445 4. Reactor according to claim 3, characterized in that several packages of carrier elements are arranged distributed over the circumference of the reactor, the plate-shaped carrier elements being arranged parallel to one another 450 and in the tangential direction of the reactor within the package.

5. Reactor according to one of claims 1 to 4, characterized in that the flow paths between adjacent support elements are 3 to 6 cm, preferably 3.5 to 5.5 cm, wide.

455 6. Reactor according to one of claims 1 to 5, characterized in that flow-porous support elements are provided.

460 7. Reactor according to one of claims 1 to 6, characterized in that support elements are provided which essentially consist of plastic particles and expanded clay particles combined with one another.

465 8. Reactor according to one of claims 1 to 7, characterized by a recirculation system which has an extractor for waste water and a feeder for waste water for discharging the flow into the central flow channel.

470 Reactor according to one of claims 1 to 8, characterized in that the extractor has a space between two plate-like elements and a line beginning in the space.

475 10. Reactor according to one of claims 8 to 9, characterized in that the extraction system is positioned a bit above the extractor of the recirculation system.

480 1 1. Reactor according to one of claims 1 to 10, characterized in that a separator system is provided in the upper region of the reactor, below the exhaust system, which serves to retain the microorganisms suspended in the waste water in the reactor.

485 12. Reactor according to claim 11, characterized in that the separator system has a partition at a distance above the upper end of the central flow channel, which covers a large part of the reactor cross section and leaves a 490 outer ring surface.

13. Reactor according to claim 12, characterized in that the partition wall extends non-horizontally in some areas and forms a gas collection space 495 in a highest area.

14. Reactor according to claim 13, characterized in that from the highest region the partition - roughly speaking - runs obliquely outwards and downwards inwards 500 downwards.

15. Reactor according to one of claims 12 to 14, characterized in that the extractor of the recirculation system is positioned on the top of the partition.

505 16. Reactor according to one of claims 1 to 15, characterized in that a first discharge line for gas formed in the reactor begins in the upper region of the reactor.

510 17. Reactor according to one of claims 1 to 16, characterized in that a second discharge line for gas formed in the reactor begins in the region of the partition.

18. Reactor according to one of claims 1 to 17,

515 characterized in that carrier plates are positioned in 15 to 40%, preferably 20 to 30%, of the reactor volume.

19. Reactor according to one of claims 1 to 18, characterized in that a flow deflector 520 is positioned on the wall in the lower region of the reactor.

20. Reactor according to one of claims 1 to 19, characterized by at least one propulsion jet mouth, which ends below the lower end of the central flow channel.

525 21. Reactor according to one of claims 1 to 20, characterized in that it is designed such that different types of microorganisms are provided as immobilized microorganisms on the one hand and as floating microorganisms on the other hand.

530 22. Process for anaerobic wastewater treatment in a reactor in which wastewater to be treated circulates, such that wastewater

(a) flows centrally from top to bottom;

535 (b) is then in contact with microorganisms suspended in the waste water in a space in the lower region of the reactor; (c) then flows in a space above the reactor along microorganisms which are arranged in the form of a structured, ordered fixed bed on support elements;

(d) and finally merges into the central flow from top to bottom. 545

23. The method according to claim 22, characterized in that after flowing along the microorganisms on the carrier elements, part of the waste water is branched off and pumped into the central flow channel.

550 24. The method according to any one of claims 22 to 23, characterized in that floating microorganism pellets are present in the treatment room.

555 25. The method according to any one of claims 22 to 24, characterized in that the microorganisms floating in the waste water are retained in the reactor by a separator system.

26. The method according to any one of claims 20 to 25,

560 characterized in that different types of microorganisms are provided as immobilized microorganisms on the one hand and as floating microorganisms on the other hand.

27. Use of the reactor according to one of claims 1 to 21 or the 565 method according to one of claims 22 to 26 for anaerobic wastewater treatment of a plant in the beverage, animal feed or food industry.

28. Use of the reactor according to one of claims 1 to 21 or the 570 method according to one of claims 22 to 26 for anaerobic wastewater treatment of a plant in the paper or textile industry.