EP2467335A1

EP2467335A1 - Reactor for anaerobically purifying waste water comprising multi-phase separator devices

Info

Publication number: EP2467335A1
Application number: EP10739876A
Authority: EP
Inventors: Axel Gommel; Dieter Efinger; Ronald Mulder
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH; Aquatyx Wassertechnik GmbH
Priority date: 2009-08-18
Filing date: 2010-07-12
Publication date: 2012-06-27
Also published as: WO2011020651A1; CN102471109A; CN102471109B; DE102009037953A1; US20130037468A1; US8663468B2

Abstract

The invention relates to a reactor for anaerobically purifying waste water (1), particularly waste water (1) from the paper industry, comprising a reactor vessel that has at least one inlet (2) for supplying waste water (1) to be purified into the reactor, at least one outlet (3) for discharging purified water, at least one sediment filter (4) and at least two multi-phase separator devices (5, 6) arranged on top of one another. The aim of the invention is to improve the capacity of the reactor with as little effort as possible in that at least two multi-phase separator devices (5, 6) are designed differently.

Description

REACTOR FOR ANAEROBIC CLEANING OF WASTEWATER WITH MULTI-PHASE DISCONNECTING EQUIPMENT

The invention relates to a reactor for the anaerobic purification of wastewater, in particular of waste water from Papierind ustrie umfassend a reactor vessel with at least one inlet for supplying wastewater to be cleaned in the reactor, at least one outlet for discharging purified water, at least one sediment and at least two multi-phase separators arranged one above the other. For wastewater treatment, a variety of mechanical, chemical and biological processes and corresponding reactors are known. In biological wastewater treatment, the wastewater to be treated with aerobic or anaerobic microorganisms is contacted, which contains the organic impurities contained in the wastewater in the case of aerobic microorganisms predominantly to carbon dioxide, biomass and water and in the case of anaerobic microorganisms mainly to carbon dioxide and methane and only reduce a small part to biomass.

The biological wastewater treatment process in recent years are increasingly carried out with anaerobic microorganisms, because in the anaerobic wastewater treatment must not be introduced into the bioreactor under high energy consumption, in the purification of high-energy biogas is generated, which can be subsequently used to generate energy, and much lower Amounts of excess sludge are generated.

Depending on the type and form of the biomass used, the reactors for anaerobic wastewater treatment are subdivided into contact sludge reactors, UASB reactors, EGSB reactors, fixed bed reactors and fluidized bed reactors. While the microorganisms in fixed bed reactors adhere to stationary carrier materials and the microorganisms in fluidized bed reactors adhere to freely movable, small carrier material, the microorganisms in the UASB and EGSB bacteria Reactors used in the form of so-called pellets. Unlike UASB (upflow anaerobic sludge blanket) reactors, expanded granular sludge bed (EGSB) reactors are higher and have a much smaller footprint at the same volume.

In the case of the UASB and EGSB reactors, the wastewater or a mixture of wastewater to be purified and already purified wastewater from the outlet of the anaerobic reactor is fed to the reactor via an inlet in the lower reactor region and passed through a sludge bed containing microorganism pellets located above the feed.

In the degradation of organ ischen compounds from the waste water form the microorganisms in particular methane and carbon dioxide-containing gas (which is also referred to as biogas), which partially accumulates in the form of small bubbles on the microorganism pellets and partly in the form of free gas bubbles in the reactor upwards increases. Due to the accumulated gas bubbles, the specific gravity of the pellets decreases, causing the pellets to rise in the reactor. In order to separate the biogas formed and the rising pellets from the water, separators are usually arranged in the middle and / or upper part of the reactor, under the ridge of which biogas accumulates, which forms a gas cushion, including a flotation layer of microorganism pellets and wastewater is located. Purified water freed of gas and microorganism pellets rises in the reactor and is withdrawn via overflows at the top of the reactor. Such processes and corresponding reactors are described, for example, in EP 0 170 332 A and in EP 1 071 636 B.

In high load reactors for anaerobic wastewater treatment usually two three-phase separators are used. These consist of stacked Gassammeihauben offset among which rising biogas bubbles and ascending granulated biosludge (pellets) collects. The gas will be like already mentioned removed from the hoods. The granulated biomass either gives off its adhering gas and then sinks back to the reactor bottom or is called

Gas / water / pellet mixture passed through a pipe system in a gas separation device on the reactor head and exposed there to shear forces. This dissolves the gas from the biomass, and the granular sludge is returned to the biomass

Process returned.

The upper three-phase separator usually also forms the roof of the reactors.

The object of the invention is to improve the performance of the reactor with the least possible effort. According to the invention, the object has been achieved by the fact that, for the time being, two multiphase separation devices are designed differently. Thus, the design of the multi-phase separators can be better adapted to the conditions at the installation site in the reactor vessel and the specific tasks that are associated with it.

The lower multi-phase separator, which closes the high-load zone in the lower reactor region, preferably has the task of separating most of the resulting biogas. Here it must be ensured that the occurring gas quantities are captured and the gas / sludge / water mixture is safely led into the internal circulation circuit. The internal recirculation circuit consists of a mammoth pump that delivers to the gas separator on the reactor head. The separated gas / water mixture passes from there via a downpipe back into the area under the lower multiphase separator.

The primary purpose of the upper multiphase separator is to ensure that no granulated biomass is discharged with the clear water. She is not on - A - connected to the internal recirculation circuit. Secluded Grainy

Biomass is therefore i.A. returned to the process exclusively by sedimentation. If the space above the suspension is made gas-tight, a separate collection of gas is not required because the gas enters this Gassammeiraum independently.

Due to the specific adaptation of the multiphase separation devices, a larger settling zone between the multiphase separation devices can be dispensed with.

In these calming zones the flow of the suspension is made uniform in order to ensure a good effect of the upper multiphase separator.

This also loses tank volume, which is for the actual

Implementation process could be provided. Furthermore, it is possible by the invention that at least one

Polyphase separation device, preferably the upper, in particular the top covers only part of the reactor cross-section, which reduces the cost of manufacturing.

At least one lower, preferably the lowest multi-phase separator should be designed as a three-phase separator, which has a system of gas hoods and preferably also guide elements.

This three-phase separator is to capture the ascending gas as large as possible free hydraulic passage surfaces and direct it into gas collection facilities, from which it can be removed.

For this purpose, the guide elements should advantageously be arranged below the spaces between adjacent gas hoods. For the separation of biomass and water, it is therefore sufficient that at least one upper, preferably the uppermost, multi-phase separation device is designed merely as a two-phase separation device which provides the largest possible clarification area.

In a particularly simple embodiment, this two-phase separation device consists exclusively or at least substantially of guide elements.

Since these guide elements are preferably formed by lamellae of a lamella separator.

To save space, the slat separator should be designed with a very low height.

The lamella separator can be designed in the form of plates or in the form of plug-in polygonal elements. According to the requirements and circumstances, it may be advantageous or necessary that the guide elements are distributed over the entire cross section of the reactor vessel or distributed only over a, preferably central, partial cross section of the reactor vessel. If the lamellar separator is smaller than the reactor cross-section, it should be designed in such a way that optimal separation of the biomass takes place under the respective hydraulic conditions. In this case must be replaced by appropriate

Measures, in particular by arranged under the guide elements

Gas discharge elements are avoided that rising gas in the

Slat separator occurs.

Especially when the lamella is smaller than the reactor cross-section, but also generally, should be located in the upper part of the reactor vessel, a gas-tight Gassammeiraum, which is connected to a gas discharge line, so that rising biogas is safely collected in the gas system. At least one drain should be provided above the uppermost multi-phase separator to discharge the purified water.

By a well-designed upper two-phase separator, the anaerobic reactor can usually be driven at higher ascent rates than conventional reactors.

So that the sedimentation process is not affected by any remaining

Biogas is disturbed, it may be beneficial before the actual

To provide multi-phase separators a zone in which the suspension is subjected to higher shear forces. In this zone biogas still adhering to the biomass is sheared off so that the sedimentation properties of the granulated biomass are improved.

This can be done, for example, by locally increased flow velocities, frequent deflections or baffles in the process water flow. The

Polyphase separators are designed so that sinking granular

Biomass gets back into the process.

Since this concept, a calming zone can be much shorter, it is also possible to combine lower and upper multi-phase separators with each other and so save construction costs.

Alternatively or additionally, it may be advantageous if at least one outflow in the upper part of the reactor vessel is part of the upper, preferably the uppermost, multiphase separation device.

This allows purified water to be pumped through a drain screen, with the screen intended to retain light biomass. In this case, the screen can be provided with cleaning devices which simultaneously generate necessary pulses to shear the gas from the granulated biomass.

The drive energy could be generated for this purpose by the available geodetics. An alternative to this is the separation of biomass and water and the separation in a light centrifugal field. However, the shear forces occurring in this case may not be so high that they damage the biosludge.

In this centrifugal field, separated gas would migrate to the center.

Biomass would be deposited with the heavy fraction and could be fed back into the process.

As a driving gradient for such a separator also the geodetic height of the reactor is sufficient. In most applications, it is sufficient if the reactor only two

Has multi-phase separators, which limits the effort. If necessary, the number of separation devices can be quite higher.

The invention will be explained in more detail below with reference to several exemplary embodiments. In the attached drawing shows:

FIG. 1 shows a schematic longitudinal section through a reactor;

FIGS. 2 to 4: various lower multiphase separation devices 5 and

FIGS. 5 to 8: different upper multiphase separation devices 6.

The bioreactor shown in Figure 1 comprises a reactor vessel which is cylindrical in its middle and upper part and tapers in its lower part downwardly conically.

In the lower part of the reactor, i. in the funnel Zulaufverteilsystem 2 is housed for supplying the waste water 1 to be cleaned.

In the middle and upper reactor vessels are two multi-phase separators 5,6.

These separators 5, 6 can each have a plurality of gas hoods 7 or even multiple layers of gas hoods 7. Above the upper multiphase separation device 6 are processes 3 each in the form of an overflow, over which the purified water is withdrawn from the reactor.

On the reactor, a gas separation device 17 is arranged, which is connected via the lines 18 with the two multi-phase separation devices 5.6. In addition, from the bottom of the gas separation device 17, a sinking line 19 leads into the lower part of the reactor vessel.

Furthermore, located in the lower part of the reactor vessel, namely in the lower part of the funnel, a sediment vent 4, 4 solids or a suspension of solid and liquid can be withdrawn from the reactor vessel via the sediment and 2 through the supply line liquid for rinsing the lower reactor vessel part can be introduced.

The Zulaufverteilsystem is formed by a plurality of inlets 2, which are arranged uniformly at the bottom of the reactor vessel, here the inner wall of the funnel and lead the wastewater to be purified 1 in the reactor vessel. A high number of controllable feed lines 2 makes it possible to adjust the distribution of the supplied waste water 1 at the bottom of the reactor vessel.

During operation of the reactor 2 to be cleaned effluent 1 is introduced into the reactor vessel via the inlets, resulting in an intimate mixing between the supplied wastewater 1 and the medium in the reactor, which consists of already partially purified wastewater 1, microorganism pellets and small gas bubbles ,

The introduced waste water 1 flows slowly from the feeds 2 in the reactor vessel upwards until it is contained in the microorganism-containing sludge pellets

Fermentation zone 19 passes. The microorganisms contained in the pellets decompose the organic impurities contained in the waste water 1 mainly to methane and carbon dioxide gas. The generated gases produce gas bubbles, the larger of which detach from the pellets and bubble in the form of gas bubbles through the medium, whereas small gas bubbles adhere to the sludge pellets. Those pellets to which small gas bubbles adhere, and which therefore have a lower specific gravity than the other pellets and the water, rise in the reactor vessel until they reach the lower multiphase separator 5.

The free gas bubbles catch in the gas hoods 7 and form under the ridge of the gas hoods 7 a gas cushion. Directly below the gas cushion is formed a flotation layer consisting of microorganism pellets with small gas bubbles adhering thereto.

The gas collected in the gas hoods 7 as well as pellets and water from the flotation layer are removed, for example via an existing in the front of the gas hoods 7, not shown opening from the gas hoods 7, optionally mixed together via a mixing chamber, also not shown, and via the line 18 in the gas separator 17 out. The water, the rising microorganism pellets, and the gas bubbles that have not already been separated in the lower multiphase separator 5 continue to rise in the reactor vessel up to the upper multiphase separator 6.

Due to the decrease in the hydrostatic pressure between the lower 5 and the upper separator 6, the last small gas bubbles dissolve from the microorganism pellets that have passed into the upper multi-phase separator 6, so that the specific gravity of the pellets increases again and the pellets fall down. The remaining gas bubbles are collected in the possibly existing gas hoods 7 of the upper multi-phase separator 6 and again at the end faces the individual gas hoods 7 transferred into a gas manifold, from which the gas is passed via the line 18 into the gas separation device 17.

If there are no gas hoods 7, the gas can be collected in a gas-tight gas collection unit 15 in the upper part of the reactor vessel, which is connected to a gas discharge line.

The now purified water continues to rise from the upper multiphase separator 6 up until it is withdrawn via the overflows from the reactor vessel and discharged through a drain line 3.

In the gas separation device 17, the gas separates from the remaining water and the microorganism pellets, wherein the suspension of pellets and the wastewater is recirculated via the sink 19 into the reactor vessel. In this case, the outlet opening of the sinking line 19 opens into the lower part of the reactor vessel, where the recycled suspension of pellets and waste water with the, the reactor via the feeds 2 supplied wastewater 1 is mixed, after which the cycle begins again.

Depending on the origin of the reactor 1 fed via the feeds 2 wastewater 1, the wastewater contains more or less solids. Wastewater from the paper industry, for example, contains significant concentrations of solid fillers and lime.

After the solids-containing wastewater 1 has left the feeds 2, it rises upwards into the cylindrical reactor vessel part. The proportion of solids contained in the wastewater 1, which exceeds a minimum level of specific gravity, sinks already after leaving the feeds 2 in the downwardly tapering funnel and collects there. Further, a part of the lime contained in the waste water 1, after the waste water has risen in the mud bed zone, crystallizes on the sludge pellets, which act as crystallization centers. As a result, part of the Sludge pellets a critical specific gravity and as a result sinks from the mud bed and also accumulates in the funnel.

About the sediment 4, the accumulating at the top of the reactor vessel sediment can be withdrawn continuously or batchwise from the reactor as needed.

In order to improve the efficiency of the wastewater treatment but also to minimize the production costs, the multiphase separation devices 5, 6 are specially adapted to their tasks. In essence, this means that the bottom multi-phase separator is primarily optimized for gas capture and the top ensures that residual granular sludge can be safely separated from the clear water with them. Therefore, the lower polyphase separator 5 is designed as a three-phase separator and the upper 6 only as a two-phase separator.

Common to the shown in Figures 2 to 4 variants of a lower, extending over the entire reactor cross-section three-phase separator 5 is the presence of several adjacent gas hoods 7th

In FIGS. 2 and 3, a plurality of layers of gas hoods 7 arranged one above the other are intended to collect and remove as much gas as possible.

In the embodiment illustrated in FIG. 2, the gas hoods 7 of the superimposed layers are essentially also positioned one above the other. Here are located below and between the gas hoods 7 horizontally and obliquely extending guide elements 8, which should direct the gas bubbles to the overlying gas hoods 7.

In contrast, the gas hoods 7 of the superimposed layers are offset from one another in such a way that, if possible, a gas hood 7 of an upper layer is located above the intermediate space between two or more gas hoods 7 of a layer arranged underneath. This makes it possible to dispense with guide elements 8. The exemplary embodiment according to FIG. 4 shows a layer of gas hoods 7 and a plurality of layers of subjacent guide elements 8 underneath. These guide elements 8 run obliquely and direct the gas bubbles to the gas hoods 7.

As a result of this multiplicity of guide elements 8, shearing forces act on the pellets, which promotes the detachment of the gas bubbles from them.

The variants shown here can be easily combined with each other. Figures 5 and 6 each show an upper two-phase separator 6, over which the overflow with the outlet 3 for the purified wastewater 1 is located.

In both cases, the separator 6 of vanes 9 in the form of

Lamellae of a lamella separator formed, which are to separate the solids from the water.

This separator extends in FIG. 5 over the entire reactor cross section and in FIG. 6 only over a central part of the reactor cross section.

The selection is made according to the circumstances, in particular the strength of the

Gas attack in this area.

In Figure 5, the entire upper part of the reactor vessel, i. used over the overflow as gas collection chamber 15, from which the gas discharged via a line.

In contrast to this, in the exemplary embodiment shown in FIG. 6, a gas discharge element 10 is located below the guide elements 9 in the form of a horizontal plate extending over the entire lamella separator. This Gasableitelement 10 leads ascending gas here in the edge regions of the reactor cross section through which a gas-tight gas collection chamber 15 is located.

FIGS. 7 and 8 show an upper two-phase separating device 6 of another type. In FIG. 7, an outflow 16 leads from the upper part of the reactor into a separating vessel 12 in which the filling level lies substantially below the inlet of the outflow 16, the upper part of the separating vessel 12 with a gas discharge line 13 connected, the bottom part with a line 14 for recycling the biomass in the lower part of the reactor and between this biomass line 14 and the filling level is the outlet 3 for the purified water.

The recirculation of the biomass via the biomass line 14 should be supported with conveying aids, such as here a pump.

The gravity increases by the height of the fall it comes to the separation of biomass and water, which allows their separate derivation. The thereby separated gas migrates largely upwards and can be removed there.

As a driving gradient for such a separator, the geodetic height of the reactor is sufficient.

In Figure 8, the purified water is pumped through a sieve 11 of the drain 3, wherein the sieve 11 should retain light biomass. In this case, the screen 11 can be provided with cleaning devices which simultaneously generate necessary pulses to shear off the gas from the granulated biomass.

The drive energy could also be generated by the available geodetics.

Claims

claims

1. Reactor for anaerobic purification of wastewater (1), in particular of wastewater (1) from the paper industry, comprising a reactor vessel with at least one inlet (2) for supplying wastewater to be cleaned (1) in the reactor, at least one outlet (3 ) for discharging purified water, at least one sediment discharge (4) and at least two multi-phase separation devices (5, 6) arranged one above the other,

characterized in that

at least two multi-phase separation devices (5,6) are formed differently.

2. Reactor according to claim 1, characterized in that

a lower, preferably the lowest, multi-phase separator (5) as

Three-phase separator is formed.

3. Reactor according to claim 1 or 2, characterized in that

a lower, preferably the lowest multi-phase separation device (5) comprises gas hoods (7).

4. Reactor according to one of the preceding claims,

characterized in that

a lower, preferably the lowest multi-phase separator (5) comprises guide elements (8).

5. Reactor according to claim 4, characterized in that

the guide elements (8) are arranged below the intermediate spaces between adjacent gas hoods (7).

6. Reactor according to one of the preceding claims,

characterized in that an upper, preferably the uppermost multi-phase separator (6) is designed as a two-phase separator.

7. Reactor according to one of the preceding claims,

characterized in that

an upper, preferably the uppermost multi-phase separation device (6) of guide elements (9) is formed.

8. Reactor according to claim 7, characterized in that

the guide elements (9) are formed by lamellae of a lamella separator.

9. Reactor according to claim 7 or 8, characterized in that

the guide elements (9) are distributed over the entire cross section of the reactor vessel.

10. Reactor according to claim 7 or 8, characterized in that

the guide elements (9) are distributed over only one, preferably central, partial cross-section of the reactor vessel.

11. Reactor according to claim 10, characterized in that

under the guide elements (9) Gasableitelemente (10) are arranged.

12. Reactor according to one of the preceding claims,

characterized in that

above the uppermost multi-phase separator (6) there is a drain (3) for discharging the purified water.

13. Reactor according to one of the preceding claims, characterized in that a drain (3,16) in the upper part of the reactor vessel part of the upper, preferably the uppermost multi-phase separator (6).

14. Reactor according to claim 13, characterized in that

via a sieve (11) of the drain (3) purified water is pumped out.

15. Reactor according to claim 13, characterized in that

the outflow (16) in a separation vessel (12) leads, in which the filling level is substantially below the inlet of the drain (16), wherein the upper part of the separation vessel (12) is connected to a gas discharge line (13), the lowest part with a line (14) for recycling the biomass in the lower part of the reactor leads and between this biomass line (14) and the

Filling level is the drain (3) for the purified water.

16. Reactor according to one of the preceding claims,

characterized in that

in the upper part of the reactor vessel, a gas-tight Gassammeiraum (15) is located, which is connected to a gas discharge line.

17. Reactor according to one of the preceding claims,

characterized in that

the reactor has only two multiphase separators (5, 6).

18. Reactor according to one of the preceding claims,

characterized in that

at least one multiphase separating device (5, 6), preferably the upper, in particular the upper, covers only a part of the reactor cross-section.