DE19719323A1 - Batch tunnel fermentation of biowastes comprises combining aerobic and anaerobic treatments - Google Patents

Abstract

Tunnel fermentation process comprises combining anaerobic and aerobic treatment of biogenic materials, wastes and residues. It uses bio-boxes or tunnel fermenters producing biogas and compost. The tunnel fermenter is double-walled. Solid, viscous and liquid substrates are degraded together. A pump extracts aqueous sludge, recycling it for further decomposition.

Description

The invention relates to a tunnel fermentation process for the combined anaerobic and aerobic treatment of biogenic substances and waste in bio boxes or Tunnel fermenters for the production of biogas and compost or fertilizer or also for the biological pretreatment of Residual waste.

The invention uses more conventional technology Process of tunnel composting for aerobic Treatment of biogenic substances such as bio waste or Residual waste with a high solids content, which in so-called bioboxes or biocontainers. Tunnel fermenters are carried out.  

The development of static rotting boxes was considered based on the valuable compost from biogenic waste produce and thereby the course of the rotting as far as possible to monitor and influence, the Air supply is in the foreground. The today Usual rotting boxes can be converted and attached Supply systems connected rentals with more or less high degree of automation. If the rotting boxes in the form of the standard container dimensions built, one speaks of rotting containers. Such Rotte boxes or rotte containers are already known the processes taking place are predominantly only aerobic Processes.

The big disadvantage with the aerobic composting process is that on average about 50 kWh per ton of waste Primary energy (electricity) are consumed. In the comparable anaerobic fermentation of biogenic On the other hand, waste is obtained from the biogas energy. The previously known anaerobic fermentation processes refer to liquid or liquefied biogenic Waste.

DE-OS 31 04 769 describes a method and a Device for recovering usable heat Composting or rapid rotting, in particular vegetable waste, as well as from manure, in which the material intended for rotting before entering in roughly crushed the reactor, inside the reactor with constant confinement in a cycle various chambers or the like managed and election or alternately aerated and ventilated during this cycle is shredded again. The intended one  Bioreactor consists of a lying container with one filling opening and one inside the container arranged around a horizontal axis Agitator screw. Furthermore, the reactor in the upper Container area with another horizontal conveyor opposite conveying direction on which the Stirring screw is assigned. With this procedure only ventilated, d. H. it is only broken down aerobically and that Rottengut is in the reactor by means of the screw conveyor is stored on a mobile base, only relocated and crushed. The disadvantage is this process and reactor that it is not possible the aerobic degradation phase is an anaerobic degradation phase downstream, since no irrigation and drainage directions are available. That's why it's a complete Degradation of the biological material with this reactor not possible.

DE-OS 34 26 717 describes a portable bio Modular gas reactor for a hydro-pneumatic Method. This reactor consists of a lower part, the floor pan, which is a "fold" all around at half height for the protected installation of a pipeline with Nozzle holes for the injection of bio gas Loosening. Furthermore, the floor pan designed so that these two or more tops can record. The top is the main proofing area for the process of biological conversion of the manure. For this purpose, the upper part has tubular cross members in the central axis with a double-walled heating pipe through which Inside the preheated freshly pumped manure is pressed and heated up. With this procedure biomass in the form of liquid manure is anaerobically broken down and  loosened by blowing in biogas and relocated. The disadvantage of this method is that the process is only suitable for liquid waste and there is no possibility of anaerobic Degradation phase either pre- or aerobic degradation to connect. In addition, it is not with this reactor possible to break down solid organic substances.

In DE-GM 296 04 560 a system for two-stage anaerobic treatment of liquid organic waste. This facility exists from several transportable containers, one Pre-acidification fermentation tanks and the other one Forms methane reactor, but both are identical and with submersible mixer rollers or with a screw Mixing the biomass are equipped and the a gas outlet, gas safety devices, a Level control, a pumping circuit for the measuring and control technology and a feed pump. The disadvantage of this system is that for a treatment module with an anaerobic process always two Containers that are transported and necessary must be set up. In addition, with this The process also only degrades liquid substances anaerobically will. A treatment of fabrics with high Solid content is not possible and neither aerobic pretreatment.

From DE-PS 38 35 230 is a method and Device known that the prior art on come next. In this publication a Process for the degassing of waste materials, in which the degassable waste parts are fed to the fermenter,  described, these in at least one closed digester under anaerobic, meso- or thermophilic conditions are sprinkled and degraded. The device provided for this consists of a Container in which one or more trolley-like Digester with the waste to be degassed inserted be either as wire mesh or perforated sheet cars are made. The container contains the necessary devices for moistening, aerating the Fermenter and to extract the resulting biogas. Of the The difference is that with this procedure no vertical forced ventilation according to the aerobic Intensive rotting and no mass transport with wheel loader, Conveyor belt, moving floor or similar, but only with a separate container is possible.

It is therefore an object of the invention to use a batch process for single-stage anaerobic and aerobic treatment create, primarily from solid biogenic waste high solids content, but also liquid or pasty biogenic waste can be treated by the Solid is used as a fixed bed, with the advantages aerobic treatment of high biogenic waste Solids content and the benefits of anaerobic Treatment of liquid biogenic waste in one Container with a simple logistics for the Mass transport.

To solve this problem, a method with the Features of claim 1 proposed.

The batch process or batch fermentation provides is a closed system in which the substrate  Partial air and water during fermentation be added.

Batch fermentation has the advantage that a Combined aerobic and anaerobic treatment of the biogenic Materials are made using an advanced process a new beginning process over a corresponding one Coupling of both processes started. Any batch process first goes through the aerobic, then the anaerobic and finally the aerobic phase again. By a defined residence time of the substrate at constant temperature are both in the aerobic as well in the anaerobic environment necessary for hygenization Conditions met.

Another advantage of the process developed here batch fermentation is the fact that this Process the treatment of a variety of biogenic Substances that are solid, liquid, pasty or gaseous can, enables. The biological treatment of biogenic substances with high solids content is available especially suitable for structurally rich materials, as one adequate degassing, ventilation and drainage must be guaranteed. Moist materials (e.g. Fruit waste) to pasty or liquid substrates (e.g. Sewage sludge) or liquid manure However, the process is very good both aerobic and anaerobic treat in a co-fermentation with solid substances. The treatment of such aqueous nutrient-rich media is used in these procedures by percolation Media via a process water and a separate one Sludge cycle on a settled in the stable Methane formation phase of rent from solids  enables. The rent works as organic active fixed bed.

Similar to the liquid materials, can also with gaseous materials are processed, which then in the rent can be blown from solids and mix and loosen them at the same time, so that gaseous pollutants of gases or air as well biodegradable or in biological harmless substances can be converted.

Another advantage is that the Plant operation necessary electrical energy for Preparation, ventilation and transport of the material can be obtained directly from the process because in the combined aerobic and anaerobic treatment of organic materials due to the anaerobic biochemical degradable energy in the form of Biogas is created with an energy content that is far above the need for treatment.

The device for carrying out a batch process consists of a tunnel that compared to the previous one known red tunnel has been significantly changed, since the principle of forced ventilation through structural and process engineering measures must be supplemented in such a way that the biogenic substances are both aerobic and anaerobic can be treated. For this, the side walls and the bottom of the tunnel is double-walled and into the inner side walls, the partitions closable ventilation and drainage slots built-in.  

The starting point is a rectangular cell, the two Side walls, a ceiling, a floor and one rear wall and one in the front area has rectangular opening in which a gate with a Special seal is arranged. On the back wall is on a module is arranged on the outside, in which the central Control, the pumps for process water and sludge circuit run, the compressor for ventilation and the ent speaking pipelines are housed.

The side walls and the bottom of the tunnel are double-walled. It is located between the Side walls and the partition walls arranged in front of it or partitions that consist of two superimposed perforated panels are made up of a kind of curtain form, or which, depending on the operating state by the moving against each other in the open state allow horizontal gas and water drainage or in closed state an even vertical Forced ventilation allow a cavity, the space for a drainage line with a slope into a swamp in the Plant and control module there.

Unlike the side walls, the floor is a roof profile trained so that the process water and sludge can run sideways so that the highest Point is in the middle and the lowest points the two side walls, where the drainage pipes are are located, each with a slope to the swamps in the Lead system and control module. About this so molded bottom is the second floor on which the solid biological substances, a rust-like one Floor with fixed ventilation and  Drainage slots is formed, arranged and which is supported on the lower floor by means of supports, so that between the bottom floor and the floor with the Ventilation and drainage slots in floor chambers arise through the top floor of that actual fermentation room to be separated. This Floor chambers serve as a catchment for that Process water and secondly as a sump or sedimentation basin for the sludge or other liquid biological substances, that contain suspended particles so that they settle can and that this paragraph then pumped out as sludge can be. The floor under the floor chambers should also have underfloor heating to prevent the process water in the bottom chambers cools down and at the same time the temperature in the Tunnel can be controlled or regulated.

The arrangement of the open or closed side walls creates the conditions for both the necessary uniform drainage and degassing as well even ventilation of the introduced into the fermentation room Materials. During the aerobic phase they are Drainage slits closed on the sides.

Due to the fact that the horizontal gas and Water resistance in a rent many times higher than the vertical one, are anaerobic in operation the side slits stood open so that both the process water run off as well as the biogas to the Sides can escape.

To initiate and maintain the anaerobic Phase are the double wall tunnels with process cycles  fitted. The first process cycle concerns this Process water coming out of the bottom of the bottom chambers is sucked off via pipes by means of a pump and from this then via pipes or through a intermediate heat exchanger through to a Nozzle that is centered in the ceiling of the container or Double wall tunnel is arranged, is pumped and by means of this by spraying onto the substrate can be distributed so that a channel formation in the Substrate is prevented.

The second cycle concerns the sludge contained in the heatable mud sump collected in the bottom chambers, pumped out through pipes using a slurry pump and is led to a nozzle via further pipelines, the middle in the ceiling of the double wall tunnel or Container is arranged. This second circle of mud run provides a separate circuit to the process water cycle.

The components of the process circuits described, such as the Ring lines, pumps etc. are in the module housed, which on the rear wall of the Tunnel fermenter or biocontainer is attached outside. On the one hand, this module is the central one Control unit for the container or tunnel fermenter housed and on the other hand a compressor for Forced ventilation of the tunnel fermenter or container, of pipelines with nozzles that are vertical Open forced ventilation in the floor chambers, connected is. This ventilation is for initiation and Maintaining the aerobic phase is necessary.  

The tunnel fermenter has in the upper area of the Side walls of valves through which the resulting biogas either with its own pressure in a gas storage or via a pressure control valve in existing gas lines can be fed.

For safety reasons (explosion protection) is the gas discharge valve designed as a pressure relief valve, so at suddenly arising excess pressure gas to the outside can be drained. This pressure relief valve is as Pressure control valve designed, for safety reasons (Ex protection) in the anaerobic process phase a little Overpressure is guaranteed by means of this valve is controllable or regulatable. Alternatively, it can Pressure control valve also as a separate valve for Gas extraction valve can be formed. For security To increase further is the gate that is on the front Front of the double wall tunnel or container through which the filling and emptying of the Tunnels with conventional technology via wheel loaders, milling machines or moving floors, as a special gas and waterproof gate.

The tunnels, boxes or cells are made of steel, Reinforced concrete, GRP or HDPE in modular cell construction created and the side walls, the ceiling and the floor are coated with a heat insulating material, thus the temperatures necessary for the processes are kept, and not by external influences, e.g. B. low temperatures at night or in winter, can be changed. He usually has one rectangular or square shape. Because every tunnel or Container its own supply systems in the module  has the possibility that several individual Tunnels put together like building blocks to form a large system what for each tunnel or container special Coupling devices are provided.

The optimal adaptation to the throughput (up or down scaling) can be both about the variable size of the Single module as well as the number of fermenters tunnel. The process modules of the single cells are through gas, air and process water pipes connected and can be controlled from a central control room being controlled. Via one or more central Supply units can process water storage, central compressor systems etc. can be arranged.

The invention uses more conventional technology Tunnel composting process for pure aerobic Treatment of biogenic substances (organic waste, residual waste) back. The principle of forced ventilation is through structural and process engineering measures supplemented in such a way that the biogenic substances with high solids contents can be treated both aerobically and anaerobically. For this purpose, closures are made in the side walls of the tunnel bare ventilation and drainage slots installed. For the irrigation and drainage of biogenic substances both process water and slurry pumps as well Heat exchangers, nozzles and drainage installed. The Treatment takes place according to the batch process, whereby a advanced process a new beginning process via a corresponding coupling of both processes started. Each batch process first goes through the aerobic, then the anaerobic and finally the aerobic phase. The one required for sanitation  Defined residence time of the substrate is both in the aerobic as well as maintained in the anaerobic environment.

Advantageous embodiments of the invention explained below with reference to the drawings. It demonstrate:

Fig. 1 shows a cross section through a tunnel with the lateral irrigation and vent slots in the closed state during the aerobic phase,

Fig. 2 shows a cross section through a tunnel with the lateral irrigation and vent slots in the open state during the anaerobic phase,

Fig. 3 is an enlargement of a lateral double wall and the intermediate wall with the irrigation and vent slots

Fig. 4 is an enlargement of an area of the floor with the intermediate floor above.

FIG. 4a is a detailed enlargement of the intermediate wall along the section AB in Fig. 4,

Fig. 5 shows a cross section through a tunnel with the illustrated process circuits, each circuit having a separate nozzle for the introduction of the media, and

Fig. 6 is a longitudinal view of a tunnel.

Fig. 1 shows a tunnel 100 , which has a box 11 , which consists of a floor 11 a, a ceiling 11 b and two side walls 11 c, 11 d, such that the tunnel is box-shaped. The interior, which is enclosed by the ceiling 11 a, the intermediate walls 13 a and the intermediate floor 18 , is the fermentation chamber 10 , into which the solid material to be broken down is introduced. The two side walls 11 c and 11 d of the tunnel or container are double-walled by arranging an intermediate wall with irrigation and ventilation slots in the closed state 13 a, in front of the side walls 11 c and 11 d, in such a way that between the outer walls 11 c and 11 d and the intermediate wall 13 a arranged in front of it, a hollow chamber 12 is formed, at the lower end of which a drainage 21 is arranged in the area of the bottom for sucking off the process water or the sludge.

The bottom 11 a is also double-walled, such that the bottom 11 a, the surface of which is formed as an inclined plane 17 , which has its highest point in the middle and tends to the side walls 11 c, 11 d, so that the process water and the sludge can drain into the drainage 21 and can be pumped out, is arranged in the intermediate floor 18 with fixed ventilation and drainage slots, which is connected via the supports 18 a to the floor 11 a of the tunnel or container, such that between the Intermediate base 18 and the base 11 a, a cavity is created, the base chamber 16 , which is separated from the fermentation space 10 by the intermediate base 18 . The bottom chamber 16 is connected to one another on the water side with the side chambers or hollow chambers 12 . The bottom chamber 16 can either be designed as a continuous chamber, then the supports 18 a of the intermediate floor 18 are designed as simple square or round columns, or the bottom chamber 16 can be divided into any number of small chambers, then the supports 18 a of Intermediate floor 18 formed as walls that run parallel to the side walls 11 c, 11 d of the tunnel or container. These then have openings at certain points through which the process water or sludge can flow.

In the center are on the ceiling 11b of the tunnel 100 pairs of nozzles 19, 20 mounted, one of which nozzle Prozeßwasserdüse is 19 through which the process water is finely distributed by means of a special training on the degraded solid material, the rent, so that channel formation in the substrate can be prevented. The other nozzle, the mud nozzle 20 , which also has a special development, is used to apply or introduce the mud onto the rent. This mud nozzle enables all types of liquid biological substances, such as. B. liquid manure or other can be introduced into the tunnel 100 and biodegraded, the rent, which consists of solids, works as a biologically active fixed bed. The nozzle pairs 19 , 20 are fixed at regular intervals over the full length of the tunnel on the ceiling 11 b.

In this figure, the situation is shown that prevails during the phase of aerobic degradation, in which the irrigation and ventilation slots of the intermediate wall 13 a are closed.

In the ceiling 11 b of the box 11 , a gas drain valve 32 is installed, for the removal of biogas for the purpose of Energiege winung and which is also designed for safety reasons as a pressure relief valve so that gas can be blown to the outside in the event of sudden excess pressure.

FIG. 2 shows a cross section through a tunnel 100 , which has the same components as the cross section already shown and described in FIG. 1, only that in this figure shows the situation that is present during the phase of anaerobic degradation the irrigation and ventilation slots of the intermediate wall 13 a are open.

Fig. 3 shows an enlargement of a side double wall and the intermediate wall 13 with the irrigation and ventilation slots of the tunnel 100 , which consists of the box 11 , which has a ceiling 11 b and a floor 11 a. The lateral double wall of the box 11 consists of the side wall 11 d and the intermediate wall 13 , through which lateral irrigation and ventilation can take place. Between the side wall 11 d and the intermediate wall 13 there is the hollow chamber 12 , at the lower end of which there is the drainage 21 , which is arranged in the sump 21 a for collecting water and mud, which is so deeply embedded in the floor 11 a, that the sludge level or the liquid level is above the drainage.

In Fig. 4 is an enlargement of part of the bottom area of the tunnel 100 , which consists of the box 11 , which has a bottom 11 a, to which the side wall 11 d and the side wall 11 c not shown here is attached. This floor is designed as an inclined plane 17 , which has the shape of a roof profile, the slope of which is directed to the side wall 11 d and that opens into the sump 21 a with the drainage 21 , so that water and mud can run off without problems. About this floor 11 a is an intermediate floor 18 with fixed ventilation and ventilation slots, which is fixed by means of supports 18 a on the floor 11 a, so that a hollow chamber 18 b is formed between the two floors, which is so deep in the floor 11 a is let in that the sludge level or the liquid level is above the drainage.

Fig. 4a shows a detailed enlargement of the intermediate wall 13 along the line AB shown in Fig. 4, from which it can be seen that the intermediate wall 13 from the sliding wall 14 with the irrigation and ventilation slots 14 a leading to the hollow chamber 12th is directed, and the fixed wall 15 with the irrigation and ventilation slots 15 a, which is directed to the fermentation chamber 10 , the wall 14 is movable up or down to the irrigation and ventilation slots 15 a of the fixed wall 15 open or close, which is indicated by the double arrow 32 .

FIG. 5 shows a cross section through a tunnel or container 100, as it has been already shown in FIG. 1, except that in FIG. 5, the process cycles of the sludge and the process water and the forced cooling are schematically shown.

The process water circuit consists of ring lines 27 in which the process water pump 25 and a heat exchanger 26 , which heats the process water and possibly filter units 25 a, which are usually designed as a gap filter, are switched on, one end of which is connected to the drainage 21 and the other other end in the center on the ceiling 11b of the tunnel or container 100 opens into a special nozzle arranged therein for process water 19, through which the water is sprayed finely on the surface of the rent and thus a channel formation is excluded in the substrate.

The mud circuit is also composed of ring lines 27, which separately extend to the process circuit, is turned on in which also a pump, the mud pump 24 and a control unit is in the front of the sludge pump 24 is located 28 by means of which additional liquid or pasty pumpable substrates, such . B. slurry can be introduced to the sludge from a reservoir 28 b by means of a bypass 28 a arranged in the control unit 28 a and one end of which is connected to the drainage 21 , while the other end opens into the control unit 28 mentioned in the process circuit, to which the mud nozzle 20 is connected, through which the mud can be sprayed finely over the surface of the lump to prevent channeling in the substrate.

The control unit 28 of the sludge circuit is automatically controlled by the central control unit of the module 23 , in which the device of the process water circuit, the sludge circuit and the compressor 29 are accommodated for forced ventilation.

The forced ventilation takes place by means of the compressor 29 , which is connected via pipes to the ventilation device 30 , on which ventilation nozzles 31 are arranged, which are arranged in the lower region of the floor chamber 16 on the inclined plane 17 .

Alternatively, the forced ventilation can also take place via the sump 21 , which is temporarily drained for this purpose, but this is not shown in the figure.

Fig. 6 shows a longitudinal view of the tunnel 100 from the side with the box 11 , which has a water and gas-tight gate 22 at its front end, for loading and unloading the fermentation chamber, which either as a single or double wing door or as a swing door , which pivots upward, can be formed and which has at its rear end on the rear wall 11 e an outside of the tunnel attached to this module 23 , which in addition to the central control unit, the compressor for forced ventilation and the devices of the sludge and process water circuit houses.

Reference list

10th

Proofing room

11

box

11

a bottom of

11

11

b ceiling of

11

11

c side wall

11

d sidewall

11

e back wall

12th

Hollow chamber

13

Partition

13

a Partition wall with irrigation and ventilation slots when closed

13

b Partition wall with irrigation and ventilation slots when open

14

sliding wall

14

a Irrigation and ventilation slots in

14

15

fixed wall

15

a Irrigation and ventilation slots in

15

16

Floor chamber

17th

inclined plane

18th

Intermediate floor with fixed ventilation and drainage slots

18th

a props for

18th

18th

b hollow chamber

19th

Process water nozzle

20th

Mud nozzle

21

drainage

21

a swamp

22

waterproof and gas-tight gate

23

module

24th

Slurry pump

25th

Process water pump

25th

a filter units

26

Heat exchanger

27

Loop lines

28

Control unit

28

a bypass

28

b Storage container

29

compressor

30th

Ventilation device

31

Ventilation nozzle

32

Gas drain valve

100

Biobox (biocontainer, tunnel fermenter)

Claims (10)

1. Tunnel fermentation process for the combined anaerobic and aerobic treatment of biogenic substances and waste in bioboxes or tunnel fermenters for the production of biogas and compost or fertilizer or for the biological pretreatment of residual waste, characterized in that the tunnel fermenter is double-walled and that solid and pasty or liquid substrates are jointly biodegradable therein, the liquid or pasty substrates being removable by means of a sludge water pump and being able to be fed back to the degradation process in a targeted manner. 2. The method according to claim 1, characterized in that the intermediate walls ( 13 ) of the double-walled tunnel fermenter consist of the displaceable wall ( 14 ) and the fixed wall ( 15 ) and that by moving the wall ( 14 ) a horizontal gas and water drainage depending on the operating state, it is permitted ( 13 a) or prevented ( 13 b). 3. The method according to claim 1 and 2, characterized in that process water is discharged via an inclined plane ( 17 ) and a sump ( 21 a) with the drainage ( 21 ), is sucked in by the process water pump ( 25 ) and with special nozzles ( 19 ) is sprayed uniformly and finely over the surface of the heap, thereby ruling out channel formation in the substrate, a process water circuit being able to be produced. 4. The method according to any one of claims 1 to 3, characterized in that the process sludge over an inclined plane ( 17 ) and a sump ( 21 a) with the drainage ( 21 ) is derived separately to the process water circuit, pumped out by the sludge water pump ( 24 ) and is evenly distributed over the surface of the rent by means of the nozzle ( 20 ). 5. The method according to any one of claims 1 to 4, characterized in that process water is heated to maintain the operating temperature of the process via the heat exchanger ( 26 ) or a floor heater and in the circuit or in an inoculation circuit by filter units ( 25 a) and a special nozzle ( 19 ) is returned to the process. 6. The method according to any one of claims 1 to 5, characterized in that the material is first aerobically aerated vertically by closing the side walls ( 13 ) using the compressor ( 29 ) and the ventilation device ( 30 ) or blower and warmed up by the self-heating if necessary is hygienized. 7. The method according to any one of claims 1 to 6, characterized, that the material is then mixed with the process water from one in the stable methane formation phase inoculated batch process running in parallel and then anaerobically filtered for several weeks uniformly tempered process water is sprinkled.   8. The method according to any one of claims 1 to 7, characterized, that the material again after the anaerobic phase is forced to the gas and vertical ventilation Manufacture odorless, the moisture too regulate and initiate aerobic post-rotting. 9. The method according to any one of claims 1 to 8, characterized in that in addition to the structured material in the tunnel fermenters also pasty and liquid substrates are treated by the rent is used as a fixed bed, which is via a control unit ( 28 ) by means of a bypass ( 28 a) can be fed to the sludge cycle from a separate storage container ( 28 b). 10. The method according to any one of claims 1 to 9, characterized in that the biogas obtained by the gas discharge valve ( 32 ), which is designed as a safety valve, is removable and can be used for energy generation.