DE19643364A1 - Process to liberate especially heavy metals from polluted soil in modular bed - Google Patents

Abstract

Modular fixed-bed reactor ('bio-refresher') accelerates the removal of especially heavy metals and/or organic residues from contaminated soil. The novelty is that: (a) the process of heavy metal removal is accelerated by the application of a defined electrical direct current; (b) the anode (14) is applied to the upper layer (4) and the cathode (15) to the drainage layer (7) in a drain pipe (10); (c) the low-voltage direct current is applied either continually, or intermittently, and may be dynamically varied; (d) the drain (10) discharges to a container (11) filled with iron ore and used as an external filter module; (e) the iron ore container has an anode in its lower layers and a cathode in the upper layer; (f) the mobility of e.g. the heavy metals in the contaminated soil is enhanced by the introduction of food industry residues containing organic acids, and (g) the container reactor (11) containing iron ore is exchanged from time-to-time.

Description

field of use

The invention relates to modular planted fixed bed reactors (biofresher) for accelerated, largely natural cleaning of heavy metals oils and / or organic pollutants contaminated soils and substrates, such as sewage sludge and water sediments. You will after the biological-physical treatment back into the material cycle returned.

Characteristic of the known technical solutions

Known technical solutions with similar tasks are in the Patent specifications DE 43 23 610 C1 called Biopolder and in DE 41 42 085 A1 has been described as a layered pile. DE 43 23 610 C1 defines the boundary between an aerobic and a Anaerobic zone is described as being constant over the treatment period ben. The layer structure from bottom to top consists of an iron ore layer that is performed anaerobically. The substrate layer in which aerobic conditions prevail. Pollutant degradation is more common measured by the interaction of oxidative and reductive processes. This type of arrangement complicates the mechanical separation of the iron ore from the substrate when the cleaning process is finished. With increased Heavy metal values in the substrate is also not an early replacement of the Iron ore possible. The sum of the heavy metals deposited is in the not to influence the technical solutions described, since the iron ore is under the substrate to be cleaned during the treatment period. The buyers for the iron ore write limit values for the heavy metal salary that must not be exceeded.

Planted fixed bed reactors for the grounding of municipal, usually unpolluted sewage sludge, are u. a. in WISSING, F .: water purification with Plants p. 42-47 (Ulmer, Stuttgart 1995).

The known solutions are mainly for a small-scale Ausle designed.

According to the circular economy law, such media as relatively lightly polluted soils, substrates, sewage sludge and water bodies dimentions containing more than 5% organic matter in this Form may no longer be deposited, accrued to a much greater extent.

The disposal path of incineration is made up of economic and capaci due to factual reasons, mainly reserved for heavily loaded batches stay.  

Paths to environmentally friendly temporary storage and at the same time Treatment with the aim of predominantly recycling the abge cleaned substrates or components will gain in economic value in the future meaning.

Aim of the invention

The aim of the invention is to use planted fixed bed reactors (biofresher) practical, location-independent, easily dismantled and environmentally friendly Right-hand, nature-adapted processes and systems for temporary storage, Treatment, and accelerated cleaning and recycling in Material cycles of with heavy metals and / or with organic pollutants to create contaminated soils and substrates.

By adding organic acids from residues from the food industry the mobility of heavy metals is increased.

Thanks to a modular change system, the iron ore is made depending on the weight exchanged.

State the nature of the invention

According to the invention the object is achieved in that fixed bed reactors (Biofresher) and other parts of the plant for accelerated cleaning of contaminated floors and substrates.

Heavy metals are adsorbed by load-dependent process control in external filter modules filled with iron ore so that when the State of saturation of iron ore with heavy metals and others Limit values a return and an immediate direct exchange through feed to ensure the smelting ability of the ore. Thereby the need for iron ore depends on the heavy metal supply limits the amount actually required.

With the application of a DC potential and if necessary one Addition of electrolytes, preferably in the form of mineral fertilizers the mobility of the heavy metal ions is increased and influenced in a targeted manner. Anodes are preferably in the top substrate layer of the modular Biofreshers and cathodes in the drain pipe filled with water or in the Base of the medium introduced.

The water flow in the fixed bed reactor and the filter modules is designed in this way tet that they have a circulatory system involving a plant sewage treatment plant results.

By controlling the water level with relative from the start of treatment high level to a declining level becomes the root growth of the marsh plants planted on the surface in an out balanced mix of flat and deep-rooted species targeted for opening lead through roots to the drain layer.

Embodiment

The invention is explained in more detail using an exemplary embodiment:

Fig. 1 cross section of the fixed bed reactor;

Fig. 2 process scheme fixed bed reactor;

Fig. 3 side view of iron ore container.

A top view of a modular fixed bed reactor (biofresher) is preferably created at ground level in the form of an elongated rectangle with mass balancing and the excavation is used to form the delimiting dams 1 . To protect the groundwater, a film lining 2 is made, which is protected on the surface by a construction fleece 5 . There is a load-bearing drivable drain layer 7 with drain pipes 10 made of inert materials. A separating fleece 6 is spread over it in order to fill in the loaded substrate 4 . The elongated design allows a receptacle volume that can be infinitely varied according to the respective batch size. Filling by driving directly onto transport vehicles takes place when three sides have been completed. The last dam on a narrow side is only closed after filling has been completed.

The surface of the modular biofresher is protected against wind and water erosion after leveling and the range of plant species preferred depending on the season. This is followed by targeted planting with swamp plants 3 which have already been proven in wastewater treatment (plant sewage treatment plant 12 ) and function as reduction plants.

The plants use the biofresher as a location and deeply root it. In the top view, the pump sump 8 can be seen which, with the pump 9 installed, serves to regulate the water level and thus the targeted root growth. Sprinklers 19 or drip hoses on the biofresher are used to irrigate the plants, to keep them moist in dry periods and to carry out the process for substrate ripening, since the natural rainfall is not sufficient.

Under special site conditions, under which no additional irrigation is possible with a self-sufficient energy supply and extended Run times the cleaning processes carried out.

The systematic lowering of the water level is adjusted via a telescopic tube 17 in the pump sump at the end of the drain tube 10. The process water conveyed from the pump sump 8 reaches the heavy metal bond in externally placed bulk material containers 11 filled with iron ore and provided with an inflow device. After the maximum absorption capacity of the iron ore for heavy metals has been reached, the container is exchanged for other receivable containers.

The process water is aftertreated in a plant sewage treatment plant 12 and / or a filter plant 13 , collected in a water reservoir 18 and can be used again for irrigation as required.

To accelerate and further secure the cleaning processes, an electrical potential in the form of an anode 14 is preferably installed in the upper region of the substrate 4 and a cathode 15 in the lower region, preferably in the drain pipe 10 . They are operated with a DC voltage.

In order to ensure continuous operation in frost periods, a closed circulation line 16 for heated media such as air or water is installed in the drain system or at the boundary with the substrate.

The system can be repeated several times by the construction described above use, at the same time a problem-free dismantling after emptying by Ver no fixed foundation structures guaranteed.

Claims (14)

1. Modular fixed bed reactor for accelerated cleaning of soils and substrates contaminated with heavy metals and / or organic pollutants, characterized in that the heavy metal mobility is accelerated in a targeted manner by applying a defined voltage potential in the form of a DC voltage. 2. Modular fixed bed reactor (biofresher) according to claim 1, characterized in that the anode ( 14 ) is preferably installed in the upper substrate layer ( 4 ) and the cathode ( 15 ) in the drain layer ( 7 ), preferably in the drain pipe ( 10 ) . 3. Modular fixed bed reactor (biofresher) according to claims 1 and 2, characterized in that the DC voltage in the low voltage area rich, permanent or intermittent and dynamically controlled is heard. 4. Modular fixed bed reactor (biofresher) according to claims 1 to 3, characterized in that an external filter module filled with iron ore ( 11 ) is preferably provided as a modified bulk container to the biofresher. 5. Modular fixed bed reactor (biofresher) according to claims 1 to 4, characterized in that on the external filter module ( 11 ), filled with iron ore, an anode is additionally arranged in the bottom region and a cathode in the upper region. 6. Modular fixed bed reactor (biofresher) according to claims 1 to 5, characterized in that further external filter modules ( 12 and 13 ) in the system of process water drainage and treatment can be switched upstream and downstream. 7. Modular fixed bed reactor (biofresher) according to claims 1 to 6, characterized in that the process water from the additional irrigation and natural precipitation from a water storage module ( 18 ) and in the drain system ( 7 ; 10 ), consisting of an inert drivable drainage layer ( 7 ) is detected, is conveyed via the pump (s) ( 9 ) in the pump sump ( 8 ) into the filter modules ( 11 and 13 ), and passes through a plant water treatment plant ( 12 ). 8. Modular fixed-bed reactor (biofresher) according to claims 1 to 7, characterized in that with the aid of a telescopic tube ( 17 ) in the pump pum sump ( 8 ) and / or corresponding pump control to start the process with a high water level, around the root growth tum To steer the water horizon in a controlled manner when the water level is lowered. 9. Modular fixed bed reactor (biofresher) according to claims 1 to 8, characterized in that in the filling and emptying phase in which one end face is open, leakage of leakage water is prevented by the fact that the water protection film ( 2 ) up to the level of loadable drainage layer ( 7 ) is pulled up and at the same time water leakage is prevented by the pump operation. 10. Modular fixed bed reactor (biofresher) according to claims 1 to 9, characterized in that to accelerate the heavy metal movement on the one hand, natural organic complexing agents, such as Carbon, amino and sugar acids and on the other hand electrolytes z. B. in Form of mineral fertilizers can be used, if necessary with the help of the irrigation system. 11. Modular fixed bed reactor (biofresher) according to claims 1 to 10, characterized in that one or more circulation line (s) ( 16 ) for heated heating media are installed to keep free from frost in the drain pipe ( 10 ) and / or above the drain layer ( 7 ) . 12. Modular fixed bed reactor (biofresher) according to claims 1 to 11, characterized in that also for planting the surfaces Plants are used to obtain renewable raw materials. 13. Modular fixed bed reactor (biofresher) according to claims 1 to 12, characterized in that the cleaned soils and substrates after Passage of the biofresher of a subsequent composting and / or Conditioning can be done with the on them grown biomass can be recycled. 14. Modular fixed bed reactor (biofresher) according to claims 1 to 13, characterized in that a specified Biofresher (Dryfresher) without additional irrigation with correspondingly extended terms to Commitment comes.