EP0675753A1

EP0675753A1 - Method of treating contaminated media in dust form

Info

Publication number: EP0675753A1
Application number: EP94904172A
Authority: EP
Inventors: Karl-Friedrich Vo; Helmut H. Hanert; Peter Harborth; Ralf Rohde
Original assignee: Ferngas Salzgitter GmbH
Current assignee: Ferngas Salzgitter GmbH
Priority date: 1992-12-24
Filing date: 1993-12-21
Publication date: 1995-10-11
Also published as: DE4244125A1; WO1994014523A1; CZ167395A3; PL309243A1

Abstract

A method and device for the disposal of media in dust form contaminated with among other things hydrocarbons and/or cyanide is characterized by the fact that the medium (4) is fed into a container (3), air (2) is passed through the medium in the container, the air (6) enriched with contaminants in the container is drawn off from the container into a bioreactor (8) containing microorganisms which degrade the contaminants biologically, the purified air is evacuated and the decontaminated medium is removed.

Description

Process for the treatment of ^b dusty contaminated media

description

The invention relates to a method and a device for the treatment of dusty media, in particular contaminated with flammable liquid hydrocarbons and / or easily releasable cyanides.

When generating e.g. Gas from coal through pyrolytic

Burns create a number of by-products, e.g. are harmful to people, animals, plants, soil, water and air. These substances include Hydrocarbons, cyanides or sulfur.

Some of these harmful substances, together with mineral constituents of the starting materials, get into the downstream gas transport lines despite upstream separation plants. There they mix and combine with the "natural" pipeline dust (such as rust), which mainly consists of iron and silicon oxides. The dusts are mainly stored in the 6 o'clock position of the pipes, sometimes but also on the walls.

When operating the gas transmission lines, the dust is removed from the

Gas flow entrained above a critical flow rate and discharged in special mobile or fixed separating systems which are located in the course of the gas transport lines or at exit points. The dusts also accumulate during repair work on the gas transmission lines (pipelines).

The dusts are difficult to dispose of because of their harmful, but above all because of their different ingredients. Since they contain flammable liquid hydrocarbons such as benzene, toluene and xylene

AGEN Storage in barrels is problematic, since the dusty medium thus contains outgassing constituents, the boiling point of, for example, benzene is only 80 ° C and, due to the resulting vapor pressures, inflate the barrels, and due to the lower explosion limit of, for example, benzene of only 1.2 vol % an explosive atmosphere forms inside the barrels.

Since the components of benzene, toluene and xylene are flammable, combustion would be an obvious choice. Here, however, the problem arises that the dusty media also contain sulfur in considerable amounts, which is undesirable in these burns.

An uncontrolled storage also conflicts with the fact that cyanides are also present in certain quantities.

The implementing provisions for the Waste Act provide for two preferred options for the disposal of dusts from the gas transmission lines:

On the one hand, the incineration, and on the other hand, the underground disposal. A third, possibly conceivable way would be landfilling over days.

However, there are practical obstacles to all three disposal methods, each due to different components of the dust:

The flammable liquid hydrocarbons prevent storage underground, the toxic cyanide components prevent storage over the day and the sulfur components are at least undesirable in incineration plants, in some cases combustion is completely rejected.

Regular disposal, for example in accordance with the implementing provisions for the Waste Act, is therefore basically not possible at the moment. At least very expensive and high-quality disposal systems have to be used, even though they are only low levels of contamination make the use of such only available in limited quantities and the high-quality disposal options less desirable.

In contrast, the object of the invention is to propose a method and a device for treating these contaminated dust-like media, which enables disposal in accordance with the provisions of the Waste Act.

This object is achieved by a generic method which is characterized by the following steps:

a) filling the medium into a container,

b) supply of air to the medium in the container

c) discharging the air enriched in the container with impurities from the container into a bioreactor with the microorganisms biodegrading the impurities,

d) removing the cleaned air and

e) disposal of the cleaned medium

With such a method, a decontamination of the contaminated dust-like medium is created, which, while protecting the environment as much as possible, annihilates the harmful ingredients as much as possible or at least reduces them to such an extent that disposal within the meaning of the Waste Act is then possible. In particular, the material contains after performing the

Process no or hardly inflammable liquid hydrocarbons and therefore no more gas-emitting constituents that may cause the container to expand or form an explosive atmosphere. In addition, the microorganisms also break down the easily releasable cyanides.

Not only is the method finally able to dispose of the contaminated dusts from gas transport lines in accordance with the regulations, it is also possible to do this with normal commercial containers without the use of particularly scarce or expensive disposal routes to lead. The residues remaining after carrying out the process are no longer explosive and are also below the limit values with regard to any harmful constituents. Landfilling is no longer a problem, and storage over days is also an option; the conditions for combustion are unchanged due to the combustible components still present in the dusts.

The process becomes particularly simple in that the contaminated dust-like medium does not have to be moved at all. It remains in its place in the container during the entire process, while air is introduced into this container, which is charged with these contaminants when flowing through the dust-like contaminated medium and then leaves the container again. This air is then exposed in a bioreactor to the influence of the microorganisms, which have been shown to degrade the contaminants very effectively. The cleaned air then leaves the bioreactor together with the degradation products, which are water (H "0) and carbon dioxide (CC), and is released into the environment.

The microorganisms feed themselves automatically from the degradation of the contaminants. The contaminated dusty media are automatically freed of their contaminants during the process. If these are removed or have dropped below a threshold value, the dusty medium can be removed from the process and disposed of. It then also contains mineral constituents such as sulfur or iron oxides and, depending on the duration of the treatment, more or fewer cyanides, which as such no longer pose major problems as such in the normal disposal and can possibly be operated with less high-quality disposal systems.

In order to provide the microorganisms with a particularly good ambient climate which accelerates the breakdown of the contaminants, it is preferred if the air enriched with contaminants is first fed to a humidifier before it reaches the bioreactor.

In order to intercept mineral constituents that may have been introduced into the bioreactor or also micro-organisms unintentionally escaping from the bioreactor, an additional cleaning is preferably carried out via an activated carbon filter before the cleaned air is removed.

To improve the living conditions of the microorganisms, it is also preferred if the contamination content of the exhaust air is measured before being fed into the bioreactor and, depending on the measurement result, the flow velocity of the supply air and / or a room or container heater and / or controlled by pre-heating air temperature of the supply air.

This makes it possible to influence the temperature inside the bioreactor, especially the temperature of the supply air and the contaminants to be broken down which are carried in with the supply air, for example in the form of feedback loops. At the same time, it can also be taken into account whether the dusty medium that is still contaminated is already there is a largely cleaned one that contains only a small amount of impurities and, of course, therefore can only offer little food to the microorganisms or whether it is still a highly contaminated medium. By increasing the flow velocity of the supply air, the inflow of possibly only minor contamination parts can be brought back to the desired value.

A further possibility for improvement is provided if, as claimed in a preferred embodiment, the air air, which is contaminated or loaded with contaminants, is mixed in from the outside before it reaches the bioreactor.

This admixture allows the impurity level to be kept at an approximately constant desired value, which is particularly favorable for the microorganisms and / or has proven to be particularly effective for reducing the contaminants. If, for example, a new container or a new drum is introduced into the system, the proportion of pollutants in the exhaust air from this container into the bioreactor will be very high, since the proportion of pollutants in this container remains unchanged at its upper value. This proportion of pollutants can be reduced by adding a relatively large amount of supply air. The total amount of the mixture can be regulated by the pre-discussed control of the total supply.

It is particularly advantageous if the supply air is introduced into the container near the bottom and the air enriched with impurities in the container is removed near the top thereof. The path of the supply air through the medium is particularly long, so that there is a large area for the possible transfer of the pollutants into the air. A device according to the invention for the disposal of dusty media, in particular contaminated with flammable liquid hydrocarbons and / or easily releasable cyanides, is characterized by a container for holding the medium, a supply device for air into the medium in the container, and a discharge device for removal of air enriched in the container with impurities, a bioreactor to which the air is supplied from the discharge device and an exhaust device for discharging the biologically cleaned air.

It is particularly preferred if the container consists of a fixed cover and a removable, replaceable lower part.

This has the advantage that a container with contaminated, contaminated dust-like medium is attached to the system and after cleaning together with its cleaned contents can be removed and replaced by a new container. It is therefore not necessary to constantly refill or handle the amount of dust to be disposed of. Once the amount of dust has been filled in, the impurities are freed from within the vessel and can subsequently be removed from the process or the entire system with the vessel. It can also be fed into this container, for example a barrel, for final storage or landfill. For this purpose, only the cover which is fixed to the system has to be adapted accordingly to the common disposal containers.

It is also preferred if an air humidifier is switched on in the discharge device between the container and the bioreactor. An air preheating unit is likewise preferably provided, which preheats the supply air before it is fed into the container. Preheated air tends to result in a better transfer of the contaminants from the dusty medium into the air. Furthermore, an activated carbon filter is preferably provided, into which the cleaned air is led out of the bioreactor before it is released. Final cleaning can be carried out here again. In addition, a sensor is preferably connected to the exhaust air unit behind the bioreactor and is connected to an alarm device to indicate a malfunction and / or a control system to shut down the system.

With such a sensor, any malfunction can be detected immediately and prevented accordingly.

Furthermore, a sensor is preferably connected to the exhaust air line upstream of the bioreactor, the output side of which is connected to a controller, which in turn is connected to the

Air preheating unit and / or a pump for controlling the flow rate of the supply air and / or a space or container heater is connected.

This sensor can be used to convert the falling degree of contamination in the course of cleaning into an increase in the flow rate of the supply air, as a result of which sufficient food is constantly supplied to the microorganisms or microorganisms. The optimal heat can also be set.

The sensor can also be used to keep the level of pollution of the air that is fed to the bioreactor at about the same level. For this purpose, a mixing device is provided in a preferred embodiment, with which unloaded supply air is admixed with the air fractions laden with impurities before they enter the bioreactor. The design with the removable, interchangeable container also has considerable additional advantages. The microorganisms need a certain amount of time to develop and to ensure optimal degradation of the contaminants. It is therefore to be expected that the system will take several weeks to arrive. By easily changing the container, it can be avoided that the system must be shut down each time another contaminated dusty medium is to be cleaned. All that has to be done is to remove the old container, which only contains cleaned dust-like medium, and to place the new container. This can happen very quickly; Usually, several containers will already be in a waiting loop in front of the system. A new start-up of the system can simply be omitted, since the microorganisms easily survive such short gaps as they occur when replacing them. This results in an almost quasi-continuous operation of the entire system.

In the following, the invention is explained in more detail with reference to the drawing in an example. It shows:

Fig. 1 shows schematically the structure of a device according to the invention.

Overall, the device represents a dust decontamination system.

Air is passed through a pump 1 via a feed device 2, here dip tubes, into the vicinity of the bottom of a container 3, which can be a barrel-like vessel. The container 3 filled with a certain amount of contaminated dusty medium 4 up to a certain height is closed with a lid 5. It can be removed from this cover 5 together with the medium 4 contained in it. The feed device 2, here the dip tubes, is arranged on the cover side and remains in the device when the container 3 is removed.

The air rising in the dust-like medium from the lower end of the immersion tubes (indicated by arrows) is enriched with pollutants depending on the operating temperature and flow rate and leaves the air space above the dust-like medium through a discharge device 6, here an exhaust air pipe which passes through the cover 5 protrudes and is plant-proof.

The discharge device 6 leads the air into a downstream humidifier 7. In this, the air is humidified to such an extent that optimal conditions for microorganisms or microorganisms arise. The air is guided from the humidifier 7 to a bioreactor 8. The microorganisms are located inside the bioreactor 8. These do not have to belong to any special culture; however, an approach made from rotted bark, compost and lava slag has proven itself in practice. After passing through the bioreactor 8, the cleaned air is passed on to an activated carbon filter 9. The activated carbon filter 9 represents a safety measure in the event of failure of the bioreactor 8 or for the absorption of harmful secondary components. From the activated carbon filter 9, the cleaned air, which only contains the decomposition products C0 _? and H _? 0 contains, released to the environment.

To achieve optimal decontamination results, the pollutant load is measured with a sensor 10 in front of or behind the humidifier 7 and fed to a controller 11. Depending on requirements, this influences various other components of the system, the influence being indicated by dashed lines a, b c and d. Therefore, a) the flow rate of the supply air in the supply device 2 determined by the pump 1 is influenced,

b) a space or container heater 12, and / or

c) the air temperature of the supply air in the supply device 2, determined by an air preheating unit 13.

d) the concentration of pollutants in the exhaust air by adding unpolluted air.

This influencing takes place in the sense of a setpoint predetermined on the controller 11. In the case of room heating 12, the system (as shown) is housed in a heat-insulated room 14. The amount of dust or the dust-like medium 4 is subjected to the process until the pollutant load measured by the sensor 10 reaches a predetermined minimum or falls below a corresponding threshold value.

On the other hand, the failure of the biofilter of the bioreactor is detected by a sensor 15 and e.g. used for alarm or shutdown of the entire system, which is indicated in the drawing by influencing the pump 1.

In this way, the method according to the invention enables the environmentally friendly decontamination of the dust and the mineralization of its biodegradable components.

Claims

Claims l 1. Process for the treatment of dusty media, in particular contaminated with flammable liquid hydrocarbons and / or easily releasable cyanides,

5 characterized by

a) filling the medium (4) into a container (3),

b) supplying air (at 2) into the medium (4) in the container (3),

c) removing the air (at 6) enriched with impurities in the container (3) from the container

(3) into a bioreactor (8) with the contaminants biodegradable microorganisms,

d) evacuation of the cleaned air (at 9) and

e) disposal of the cleaned medium (4). 0

2. The method according to claim 1, characterized in that the air enriched with impurities (at 6) 5 is first fed to a humidifier (7) before it gets into the bioreactor (8).

3. The method according to claim 1 or 2, characterized in that _Q that before the removal of the cleaned air (at 9), an additional cleaning via an activated carbon filter (9).

4. The method according to any one of the preceding claims, 5 characterized in that a measurement before being fed into the bioreactor (8) of the impurity content of the air and, depending on the measurement result, the flow rate of the supply air (at 2) and / or room or container heating (12) and / or the air temperature of the supply air (at 2) determined by preheating (13).

5. The method according to any one of the preceding claims, characterized in that to the air enriched with impurities (at 6) unloaded supply air is mixed in a mixing ratio that provides an approximately constant maintenance of the impurity content of the air in the bioreactor (8).

6. The method according to any one of the preceding claims, characterized in that the supply air (at 2) is introduced into the container near its bottom and the discharge of the air enriched with impurities in the container (3) near its top (at 6 ) he follows.

7. Device for the treatment of dusty media, in particular contaminated with flammable liquid hydrocarbons and / or easily releasable cyanides, characterized by a container (3) for receiving the medium, a supply device (2) for air into the medium (4) in the Container (3), a discharge device (6) for removing air enriched with impurities in the container (3), a bioreactor (8) to which the air is fed from the discharge device (6) and an exhaust air device for discharge the biologically cleaned air.

8. The device according to claim 7, characterized in that the container (3) consists of a fixed cover (5) and a removable replaceable lower part. ^~

9. Apparatus according to claim 7 or 8, characterized in that an air humidifier (7) in the discharge device (6) between the container (3) and the bioreactor (8) is switched on.

10. Device according to one of claims 7 to 9, characterized in that an air preheating unit (13) is provided which preheats the supply air before being fed into the container (3).

11. The device according to one of claims 7 to 10, characterized in that an activated carbon filter (9) is provided, in which the cleaned air from the bioreactor (8) is guided before delivery.

12. Device according to one of claims 7 to 11, characterized in that a sensor (15) in the exhaust air unit behind the bioreactor (8) is switched on, which has an alarm device for displaying a malfunction and / or a regulation for stopping the Plant is connected.

13. The device according to one of claims 7 to 12, characterized in that a sensor (10) in the exhaust unit in front of the bioreactor (8) is switched on, the output side of which is connected to a controller (11) which in turn is connected to the air preheating unit (13 ) and / or a pump (1) for

Control of the flow rate of the supply air (at 2) and / or a room or container heater (12) is connected.

14. Device according to one of claims 7 to 13, characterized in that an admixing unit is provided with which the unloaded supply air can be mixed with the contaminated air from the container (3) before being fed into the bioreactor (8).

15. The apparatus of claim 13 and 14, characterized in that the sensor (10) controls the degree of mixing in the admixing unit.