DE19502856A1 - Waste water treatment plant producing more methane and less sludge - Google Patents

Abstract

The supply (1) to this waste water treatment plant passes to the primary sedimentation tank (2). There is at least one transfer device (20) (recycled activated sludge pump) and thickening system (8,14) for sludge produced. Settled sewage passes to the aerobic activated sludge plant (3). An anaerobic reactor (12) digests the sludge. The original feature is the construction of thickening and/or transfer systems, with the deliberate intention of subjecting micro-organism cells in the thickened sludge to lysis. Also claimed are: (i) a device to thicken and/or transport sludge, which subjects the cells to lysis, and (ii) a sludge reduction procedure causing lysis as described.

Description

The present invention relates to a clarifying device for Waste water according to claim 1. Furthermore, the present invention an apparatus for thickening and / or conveying sewage sludge according to claim 7 and a process for reducing sludge production in sewage treatment plants according to claim 9.

The device according to the invention as well as the fiction Appropriate processes serve to inject the sludge production mass Reduce sewage treatment plants, improve drainage and biogas fermentation for an anaerobic methane transfer mentation of the sludge, the waste biomass and the to accelerate anaerobic cleaning of waste water.

Biological waste treatment results in relative large amounts of sludge, dealing with them and their economic use often leads to problems. In the aerobic biological wastewater treatment at least two types of sludge: primary sludge - that Sludge that is fed to the primary deposit of the Wastewater arises and is subject to rapid decomposition - and as the second type of sludge, the activated excess sludge, which after the biological treatment stage of the wastewater arises. This is primarily a mixture of microorganisms that arise during wastewater treatment hen and their number from the amount of the eliminated waste cleaning and the procedural conditions at the Rei is dependent. Both types of mud are in the mei Most wastewater treatment plants, especially in the large ones, through an anae robe methane fermentation processed.  

Anaerobic methane fermentation of organic substances is a Process in which a mixed culture of microorganisms under anaerobic conditions gradually biodegradable Organic mass decomposes. The end products of this cer Settlement are methane, carbon dioxide, hydrogen sulfide (Sulfane), nitrogen, hydrogen, the resulting biomass and a stabilized organic substance (another not more decomposable remaining stock).

Among the main factors affecting the course of the anaerobic Affecting decomposition include the composition of the Substrates (depending on it the specific production and the composition of the biogas), the presence of nutrients, the pH value, the buffering capacity as well as the Temperature. The economy of this process is of the dry matter concentration (solids concentration) depending on the material to be processed. For this reason the incoming material is often a thickening process subjected to this, either mechanically (centrifuges, Pressing etc.) or with the help of gravity.

For a favorable course of anaerobic decomposition the presence of a number of inorganic nutrients significant. The presence of a row is also important growth factors (growth factors) and vita mines and enzymes. For anaerobic decomposition are before hydrolytic enzymes of importance, which have a lot number of substances, such as B. also solid and high molecular weight organic substances. Some of these substances can synthesize the microorganisms themselves, others must be added from the outside.

One laboratory opportunity, biogas development at anae robes methane fermentation of sludge, waste water and other stimulating other organic substances describes the CZ-PS 242 979. The method disclosed in this patent is that the material intended for fermentation,  or directly into the anaerobic reactor, as a stimulus a separate from the laboratory wastewater treatment plant processing system mechanically or physically treated micro organism-containing biomass suspension of between 0.1 to to 10 wt .-%, preferably 5 wt .-%, based on the organization African dry matter of the material to be processed, is added.

In lytic treatment (mechanical and physical Destruction of cells) of the biomass suspension according to the State of the art is partly the content of the cells released microorganisms.

The content of microorganism cells or cells of others Organisms that result from the destruction of cell walls and / or cell membranes is released into the solution (also Zelly called sat), has a beneficial or stimulating effect the process of biological decomposition of the organic Fabrics. The lysis of the cells runs on the one hand natural way (autolysis) in dead cells, other on the other hand with the help of hydrolytic enzymes, which by Fermentation bacteria are released into the solution, and also by the artificial decomposition of microorganism organisms with the help of physico-chemical or mechanical methods.

The cell lysate stimulates the function and that Growth of microorganisms, on the other hand it contains even a series of enzymes that are organi shear substances are required. The lysate stimulates the Activity of some bacteria, the hydrogen and carbon di implement oxide, acetic acid, propionic acid, etc. and / or can release. It also increases decomposition organic mass and increases biogas production at anae robes methanization processes, reducing the Total amount of sludge produced as well as the increase of biogas production. The cell lysate can  if the production of excess animated sludge significantly influenced when used in the aeration tank sen.

The preparation of cell lysates according to the state of the art is related to the system required for this as well the amount of energy required for this is complex. This is true for all previously known methods of cell separation or destruction, such as B. this during disintegration using mechanical methods (grinding, grinding, pressing), Sonification (ultrasound treatment), cavitation, again rapid freezing and thawing, exposure to heat, etc. of the Case is.

The prior art method described above the CZ-PS 242 979 has the main disadvantage that it is a separate preparation of the cell lysate - outside of the actual clarification device - makes it necessary. As above this method is only mentioned for a laboratory scale suitable; a transfer to a large-scale process ren due to the large space requirements, the high Energy and investment costs and the additional person nal effort not practical. For example neither economically nor technically sensible sludge quantities, that accumulate on a ton scale, freeze cyclically and to defrost again.

Based on the prior art of CZ-PS 242 979 It is therefore an object of the present invention, which is in Kläran accumulated sludge were under industrial conditions less expensive and less expensive significantly lower.

This problem is solved in terms of device technology by the features of claims 1 and 7. Procedure the task is technically characterized by the features of the patent Proverb 9 solved.  

The sewage treatment device according to the invention comprises at least one sedimentation basin with at least one inflow; at least one conveyor; at least one aerobic Revitalization device; at least one thickening device treatment which releases sewage sludge; and at least one anaerobic reactor and is characterized in that the Structural thickening device and / or conveyor are designed so that the cells in the sewage sludge microorganisms contained in the thickening and / or Funding can be at least partially lysed.

In addition, the present invention provides a device for thickening and / or conveying sewage sludge supply, which is characterized in that it is structurally so is designed so that the cells ent in the sewage sludge holding microorganisms during thickening and / or conveyance tion are at least partially lysed.

Finally, the present invention provides a process for reducing sludge production in sewage plants, which comprises the following steps:
Allowing wastewater to settle in at least one sedimentation tank and conveying the sedimented sewage sludge to at least one anaerobic reactor by means of at least one conveying device and forwarding the wastewater to an aerobic activation device;
aerobic conversion of the settled waste water in at least one aerobic activation device;
Thickening the sewage sludge in at least one thickening device;
Reacting the sewage sludge in at least one anaerobic reactor; in which
the microorganisms contained in the sewage sludge and / or waste water are at least partially lysed in the thickening device and / or in the conveying device.

By the devices according to the invention or the inventions The sludge production in sewage is carried out according to the method according to the invention were significantly reduced. In that the cells of the Microorganisms in the clarifier itself or in the Thickening and / or conveying device are lysed, it also becomes possible to use these devices Processes can also be used on an industrial scale. One advantage is that the thickening and / or conveying device for thickening at the same time and / or conveying the sludge as well as for lysing the Cells can be used, which the devices or makes the process more economical. In addition, in the Devices or the method a continuous Lysing the cells with a relatively low sludge throughput possible, thereby avoiding large Sludge quantities must be processed at the same time.

Since in the devices according to the invention or the inventions method according to the invention no complex preparation of the Cell lysates outside the clarifier is more necessary thus there are no increased costs and no increased costs Energy and personnel expenses. In addition, the performance of the anaerobic reactor increased and the degradation more organic Accelerated substances, problematic substances such as B. different Xenobiotics, or toxins, are increasingly broken down that Production of combustible gas is increased and the energy bi lanz is also compared to the prior art improves.

The above-mentioned disadvantages of the prior art become thus by the device and the method for min sludge production in sewage treatment plants at  Treatment of sludge and waste biomass by anaerobic Methane fermentation and anaerobic wastewater treatment gung eliminated according to this invention.

The clarifier can at least one secondary clarifier between the aerobic activation device and the thickening have facility to improve clarification. Wei the clarifier can also function as a Take over memory or exert a buffer effect.

The aerobic activation device is preferably directly connected connected to the sedimentation tank, which is the advantage of a unit pipe system and a reduced odor shows.

The conveyor can, for example, a sludge be pump, which is preferably behind the clarifier is arranged and with an inlet to the aerobic bele exercise facility is connected. So that the aerobic on wastewater treatment can be further improved.

The thickening device is preferably a centri gap. This has the advantage that in addition to the lysis of cells substantial dewatering of the sludge can be achieved can. This can also reduce the possible transportation costs be lowered for the mud. Another advantage is also that the water content of the sludge can be adjusted can.

Furthermore, a thickening can occur after the anaerobic reactor and / or drainage device, preferably a Zen trifuge, be arranged to the mud before the end position drying and / or burning as much as possible. Also here are the above advantages of reduced Transport costs and the adjustability of the water content tes.  

A device can be used as a device for lysing and thickening Thickening centrifuge can be used. As a device for A paddle wheel, for example, can lyse and pump device can be used.

A screw conveyor can be used as the device for lysing direction and / or vacuum device and / or grinding direction and / or overpressure device, in particular press device and / or grating device and / or sound system tion device, preferably ultrasound device and / or vibration device can be used. By the system can optimally use these various options the nature of the respective wastewater and / or Sewage sludge to be adjusted. Furthermore, depending on Need to be lysed more or less, with which the Device or the method become very adaptable.

The aerobically converted wastewater can be in at least one Clarifiers are clarified and the cleaned waste water ser can be derived and at least part of the settled sewage sludge can in a thickener tion are forwarded. This has the advantage that less volume has to be processed, which means that Investment becomes more economical.

The anaerobically treated sewage sludge can also be in a white thickening device (centrifuge) who thickened the. The entire centrate is placed in the after the centrifuge aerobic activation device supplied. Part of the Zentra tes from the centrifuge can be in the aerobic reactor to the Sti mulation.

An amount of about 0.5 to 50% of the amount is preferred lysed on originally present organism cells. In order to can stimulation and / or the resulting amount of sludge being controlled.  

Part of the anaerobically converted and / or incorporated can also thick sludge is returned to the anaerobic reactor to continue mining it.

For disassembling (destruction) or for lysing a part of the Cells can thus, for example, the cells on the pump pen and / or during the centrifugation of the processed mate rials (activated or anaerobically stabilized sludge or another biomass) centrifugal force the.

Another advantage of the method is that in the anaero ben reactor a combustible gas, especially methane, is produced. The combustible gas generated in the process can be used to generate electricity, with preference the generated electricity directly to operate the sewage location and / or used for feeding into the power grid can be.

Further advantages and features of the present invention result from the description of execution examples play as well as based on the drawing.

It shows

Fig. 1 is a flowchart of an embodiment of the inventive method.

The plant shown in Fig. 1 for the application of this method comprises a primary settling tank 2 with an inflow 1 of raw sewage. A primary sludge 11 is passed into an anaerobic reactor 12 . The waste water from the settling tank 2 is Primae ren exercise device in an aerobic biological Bele 3 out, the mixture of the activated sludge device 3 is fed into a secondary settling tank 4 where it comes to the separation of the purified waste water. 5 Part of the settled activated sludge 6 is pumped back with a return sludge pump 20 as a conveyor in the Belebungsein device 3 . The excess activated sludge 7 is fed into a thickening centrifuge 8 , where sludge thickening and the breakdown of cells of part of the microorganisms occur. A centrate 9 is returned to the activation device 3 . The thickened sludge is fed into the anaerobic reactor 12 . A reaction mixture 13 from the anaerobic reactor 12 is passed into a thickening or dewatering centrifuge 14 , where dehydration of the stabilized sludge and decomposition of cells of part of the microorganisms occurs. A centrate 17 comes back into the activation device 3 and / or part of it is fed to the anaerobic reactor 12 . The dewatered anaerobically stabilized sludge 15 passes through an outlet 18 to a landfill and / or part 16 thereof is returned to the anaerobic reactor 12 .

The part of this system where there is partial destruction of the cells of the microorganisms is composed of a thickening centrifuge 8 and the dewatering centrifuge 14 and / or the sludge pump 20 , it being in the centrifuges by centrifugal force and in the sludge pump by a built-in grinder for increased destruction of cells and microorganisms.

To prepare the stimulating reagent, it is also possible to use activated sludge on the one hand and anaerobically stabilized sludge on the other hand, either directly from the given reactor or from another, well-working reactor. In the former case, the excess activated sludge 7 is guided into the thickening centrifuge 8 , where, in addition to the sludge thickening, decomposition / lysis of part of the biomass cells occurs, the centrate 9 returning to the activation device 3 and the thickened part 10 into the anaerobic reactor 12 is led to sludge stabilization. In the other case, the anaerobically stabilized sludge 13 is fed into the dewatering centrifuge 14 , where, in addition to the sludge dewatering, part of the biomass cells are broken down, part of 5 to 30% of the center 17 and / or part of the 5 to 30% dewatered sludge 16 is returned to the anaerobic reactor 12 for sludge stabilization.

The method according to this invention is thus economical more advantageous from the point of view of use in industrial Benchmark compared to the prior art of Lysatzu preparation. In this way it is possible to simultaneously to stimulate aerobic and anaerobic biological clarification processes lieren.

An application according to the present invention has an effect in the technical implementation generally by a ver improvement of a number of technical parameters. At the processing of dissolved impurities (anaerobic waste water water cleaning) and anaerobic sludge stabilization the following results occur: The performance of anaero ben reactors is increased, the decomposition of organic substances is accelerated, the decomposition of organic substances in the course the stabilization process is also accelerated (in the case of sludge, the deepening of the anaerobic degradation, in Waste water the possibility of problematic substances, such as. B. different to break down xenobiotics or toxins), the biogaspro production is increased, the production of stabilizing Sludge is reduced, the drainage ability of the anaerobically stabilized sludge is improved and the the energy balance of the process compared to classic design is also improved.

example 1

The function and the technical use according to the invention can be seen in FIG. 1. A thickening centrifuge 8 was used as the thickening device as the main system for preparing the stimulating reagent, ie for breaking down or lysing part of the biomass cells of the excess activated sludge. To determine the amount of released cell lysate, the concentration of the dissolved organic substances, expressed as BOD in the input stream 7 and in the output stream 10 from the thickening centrifuge 8, was determined with the following result:

Input stream ( 7 ) BOD _{5 (dissolved)} - 140 mg / l
Concentrate (stream 10 ) BOD _{5 (dissolved)} - 630 mg / l

The tests of the methanogenic activity were carried out with input stream 7 and concentrate 10 . The concentrations of the suspended substances in both types of current were designed so that they were the same. Tests were carried out under the same conditions and with the same inoculum concentration. Anaerobically stabilized sludge from an anaerobic reactor was used as the inoculum. The biogas production was determined separately for each stream and for the mixture of both streams with the same amount of all substances. The biogas production from the same amount of all substances was 10.08% higher for concentrate 10 than for input stream 7 . The production result for the mixture showed an increase of 13.32% and 31.2% compared to the theoretical value depending on the load on the anaerobic inoculum ( 0.54 and 0.27 g COD / g organic content in one gram of the undissolved Substances (loss of ignition). The theoretical value represents the sum of the production gas value of the same amount for each electricity individually.

Example 2

Check the stimulation influence of the cell lysate anaerobic degradation with simple substrates.  

Methanogenic activity tests of anaerobic co-fermentation with formic acid, acetic acid, propionic acid and glucose were carried out. In all cases, the same amount of inoculum was used, one series of experiments was carried out with the addition of thickened excess activated sludge concentrate (stream 10 ) and the other with the addition of the same amount of excess activated sludge entering before centrifugation (stream 7 ). The co-fermentation of the complex materials with simple substrates sometimes leads to an increase in the degradability of some components of the complex substrates. Co-fermentation of the same amount of the tested sludge with glucose showed a 41.8% increase in the degradability of the incoming sludge and 51.3% of the concentrate (difference in effect 11.3%). The co-fermentation with formic acid was only positive with 13.5% concentrate (difference in effect 33%).

Claims (20)

1. Sewage treatment plant with: at least one sedimentation basin ( 2 ) with at least one inflow ( 1 );
at least one conveyor;
at least one aerobic activation device ( 3 );
at least one thickening device ( 8 , 14 ) which discharges sewage sludge; and
at least one anaerobic reactor ( 12 );
characterized in that
the thickening device ( 8 , 14 ) and / or Förderein direction are structurally designed so that the cells of the microorganisms contained in the sewage sludge are at least partially lysed during the thickening and / or conveying. 2. Clarification device according to claim 1, characterized in that at least one secondary clarifier ( 4 ) between the aerobic activation device ( 3 ) and the thickening device ( 8 , 14 ) is arranged. 3. Clarification device according to claim 1 or 2, characterized in that the aerobic activation device ( 3 ) is connected to the settling tank ( 2 ). 4. Clarifier according to one of claims 1 to 3, characterized in that the conveying device is a sludge pump ( 20 ), which is preferably arranged behind the secondary clarifier ( 4 ) and with an inlet to the aerobic activation device ( 3 ) is the verbun. 5. Clarifier according to one of claims 1 to 4, characterized in that the thickening device ( 8 , 14 ) is a centrifuge. 6. Clarifier according to one of claims 1 to 5, characterized in that after the anaerobic reactor ( 12 ) a thickening and / or drainage device, preferably a centrifuge ( 14 ), is arranged. 7. Device for thickening and / or conveying sewage mud, characterized in that it is structurally designed so that the cells in the Sewage sludge contained microorganisms at the one thickening and / or promotion at least partially lysed (disassembled). 8. The device according to claim 7, characterized in that that they are for at least partially lysing Mikroor ganisms a centrifuge device, and / or show felradeinrichtung and / or screw conveyor and / or vacuum device and / or grinding device and / or overpressure device, in particular press direction and / or grating device and / or sound system tion device, preferably ultrasound device and / or vibration device. 9. A process for reducing sludge production in sewage treatment plants, which comprises the following steps:
Allowing wastewater to settle in at least one settling tank ( 2 ) and conveying the sedimented sewage sludge to at least one anaerobic reactor ( 12 ) by means of at least one conveying device and forwarding the wastewater to an aerobic activation device ( 3 );
aerobic conversion of the settled wastewater in at least an aerobic activation device ( 3 );
Thickening the sewage sludge in at least one thickening device ( 8 , 14 );
Converting the sewage sludge in at least one anaero ben reactor ( 12 );
characterized in that
the microorganisms contained in the sewage sludge and / or waste water are at least partially lysed in the thickening device ( 8 , 14 ) and / or in the conveying device. 10. The method according to claim 9, characterized in that the aerobically converted wastewater in at least one after clarifier ( 4 ) is clarified and the cleaned wastewater ( 5 ) is derived and at least part of the settled sewage sludge in a thickening direction ( 8 , 14 ) is forwarded. 11. The method according to claim 9 or 10, characterized in that the anaerobically converted sewage sludge is thickened in a further thickening and / or dewatering device ( 8 , 14 ). 12. The method according to any one of claims 9 to 11, characterized in that at least part of the supernatant obtained from the thickening device ( 8 , 14 ) is returned to the aerobic activation device ( 3 ). 13. The method according to any one of claims 9 to 12, characterized characterized in that one as a thickening device Centrifuge used. 14. The method according to any one of claims 9 to 13, characterized characterized in that an amount of about 0.5 to 50% of the Amount of organism cells originally present is lysed. 15. The method according to any one of claims 10 to 14, characterized in that part of the sewage sludge settled in the secondary settling tank ( 4 ) is pumped back with a back-sludge pump ( 20 ) into the aerobic activation device ( 3 ). 16. The method according to any one of claims 9 to 15, characterized in that part of the anaerobically converted and / or thickened sludge is returned to the anaerobic reactor ( 12 ). 17. The method according to any one of claims 9 to 16, characterized characterized in that the cells by a centrifuge device, and / or paddle wheel device and / or Screw conveyor and / or vacuum device device and / or grinding device and / or overpressure direction, in particular pressing device and / or Zer friction device and / or sound system, before preferably ultrasonic device and / or vibration device can be lysed. 18. The method according to any one of claims 9 to 15, characterized in that a combustible gas, in particular methane, is generated in the anaerobic reactor ( 12 ). 19. The method according to claim 18, characterized in that the combustible gas generated in the process to electricity generation is used, preferably the generated electricity used to operate the sewage treatment plant becomes.