DE4124779A1 - Surface water treatment - converts sediment surface to mineral layer, to separate mud from water - Google Patents

Abstract

To treat eutrophic surface water, with a muddy bottom, water or a water/gas mixture with or without chemical additives is fed to the water above the sediment until the nutrients in the upper level of the sediment form minerals to form a sepg. layer between the water and the lower levels of the sediment mud. Water enriched with oxygen is fed in to pref. nitrify the sediment. After nitrification, eddied sediment is mixed with water low in oxygen to give denitrification, followed by the addition of a precipitation agent. The precipitating agent can be added at the end of nitrification and before denitrification. At the same time as denitrification, an upwards stream of gas/water/plankton mixt. is formed through the action of the fine bubbles and local pressures with a biochemical reaction, for the mixture stream to pass into a degassing stage. The concn. of matter and harmful substances in the water is measured and controlled to eliminate them and, at the same time, the biochemical cleaning stages are ended. The cleaned water, enriched with oxygen, is either returned to the water or recirculated to treat the sediment. ADVANTAGE - The technique prevents the release of nutrients from the sediment mud into the water on contact with it.

Description

The invention relates to a method for reactivation eutrophicated surface waters, especially of soil, Lakes, rivers and artificial waters with high Mud thickness, and a device for implementation of the procedure.

The eutrophication of water, i.e. H. the entry of Plant nutrients, especially through N and P compounds in this is a natural process. Not closed Purchases of materials from industry, agriculture and from Municipalities place a heavy burden on the Surface water and ultimately also groundwater. they can the ecological balance of aquatic systems and thus destroy the biotope. Despite external, technical Measures for water remediation and avoidance of the load and Water remediation is often only very harmful difficult to achieve because the stored in the sediments internal burden continues the process of eutrophication.

There are ways to reduce the internal burden known methods like

• - dredging measures
• - deep water ventilation
• - nutrient precipitation
• - sediment conditioning.

The first two measures are best known, they are however, sometimes very costly and time consuming. The last both measures are partially preferred in the Wastewater treatment and sludge treatment more modern Sewage treatment plant technology applied. A large-scale application this method is not known in open water.

In DE-OS 36 26 610 and DE-OS 36 30 032 is one Device for the surface treatment of water floors with deposited, low-oxygen sedimentation, in particular  through ventilation. Are on one movable float height-adjustable working arms in Form of tubes arranged with one end the surface over the sediment as well as in this end area a nozzle-like opening of water under pressure to whirl up of the sediments. The swirled sediments will mixed with oxygen. The disadvantage is that no controlled, self-contained treatment of the Water floor takes place and the resulting turbulence with releases nutrients into the water and its layers and into transports the trophogenic zone. Call this way with the opposite of stimulating biomass production in water of the desired effect.

Other methods of introducing oxygen into water for internal water remediation z. B. in DE-OS 37 24 692 and DE-OS 36 15 629 described without the internal Is directly counteracted by the sediments.

Publications are also known in which a Sediment conditioning through injections of Precipitants, e.g. B. with iron chloride or with nitrate Phosphorus binding has been described. The disadvantages of this Treatment method is that the sludge in the Sediment is hardly considered. This occurs after the Treatment or if treatment is interrupted Nutrient solution (phosphates and nitrates) from the sediment and the water continues to be enriched with nutrients. Other treatments using injections are required.

The object of the invention is a method for reactivation eutrophicated surface water and a device for Implementation of the process evolve by avoiding will that the existing sediment at the bottom of the water releases nutrients to surrounding waters.

According to the invention the object is achieved in that  open water in the opposite of the free water shielded sediment using water or a water-gas mixture or is initiated without chemical metering until the removal of nutrients from the sediment such Mineralization in an upper layer of the sediment causes the lower layers of sediment to leave the water are separated.

The method is advantageously characterized in that that oxygenated water to initiate a Nitrification is introduced into the sediment and after Complete the nitrification by mixing the whirled up sediments with almost oxygen-poor water to initiate denitrification.

To bind the phosphorus present in the sediment proposed, following the aforementioned Process steps of precipitant in the water cycle to add. The addition of precipitants can already be carried out when nitrification is initiated.

Another feature of the invention is that simultaneously with the initiation of denitrification by the Buoyant effect of the fine gas bubbles and the local ones Pressure conditions an upward gas-water Seston mixture stream is generated in which the biochemical reaction continues, and the gas-water Seston Mixture flow finally in a load and Pollutant treatment system flows where the degassing takes place.

It is also suggested that by measuring, controlling and regulate the load and pollutant concentration in the water recorded and with known methods the load and Pollutants eliminated from the water, at the same time the biochemical purification stages and that purified and oxygenated water either in the water or in the sediment treatment cycle is fed.

A device for performing the invention The method is then characterized according to the invention by a  Floating body and a diving body, both by one flexible to different water depths and water levels adaptable connection are interconnected. Here is in advantageously the connection is designed as a riser. In the riser are to continue the biochemical Reactions within the gas-water Seston mixture consecutive mixing elements and trickling filter arranged.

An embodiment of the invention provides that on the outside Riser pipe one or more downpipes are arranged, the upper opening in the pollutant treatment plant and its lower opening in free water or in the immersion body. Another feature of the invention is that in lower part of the immersion body probes in the sediment direction are movable, are arranged. At the bottom you can Probes can be nozzle-shaped. It is expedient the floating body with a pollutant treatment system connected.

For the first time, the solution according to the invention combines one Combination of oxygenation and sediment treatment for effective remediation of eutrophied shallow water. By natural and artificial sediment traps can economic benefits of the proposed method further be improved. The method also has the advantage that the waters after the sediment treatment no longer from nutrient-rich silt can be negatively affected. The process ensures that the reaction space is above of the sediment to be treated from the surrounding water is shielded so that the treatment is localized remains. A cloudiness of the water and a destruction natural layers of water are thus largely prevented.

The invention will be explained in more detail using an exemplary embodiment explained. In the accompanying drawings:  

Fig. 1 is a schematic representation of a device

Fig. 2 is a schematic representation of a device for use in shallow waters

Fig. 3 is a schematic representation of a device for use for a flat treatment of the subsoil.

The device essentially consists of a floating body 1 , a diving body 3 and a tubular connection 2 , which connects the floating body 1 and the diving body 3 with each other. The floating body 1 itself is designed in the form of a pontoon and has buoyancy bodies 4 which ensure the floating ability of the overall device. In addition, a pollutant treatment system 6 , supply devices 5 and an opening 7 for a supply air line 11 and a degassing pot 8 are arranged on the floating body 1 .

The diving body 3 is open at the bottom and provided with a ballast and bilge system. This ballast and bilge system enables the immersion body 3 to be stationed above the water bed 20 or to provide the necessary buoyancy when surfacing. In the lower part of the immersion body 3 , tubular probes 19 are arranged, which are mounted in the immersion body 3 in the rest position. At the lower end, these probes 19 are nozzle-shaped. The probes 19 are operated in a known manner, e.g. B. by a pulling device 21 which can be actuated from the floating body 1 .

On the outer circumference of the immersion body 3 , an ejector 17 and an underwater pump 16 are arranged, with which a water-gas mixture is generated. In the exemplary embodiment, air at atmospheric pressure is used as the gas.

The connection 2 is so flexible that different water depths can be processed. In the connection 2 , a riser pipe 9 is arranged, which connects the immersion body 3 with the lower part of the pollutant treatment system 6 . The inside of the riser pipe 9 is filled with trickling filters 14 . At the lower end of the riser 9 , a mixing element 15 is arranged, which serves to swirl the air-water-Seston mixture rising from the immersion body 3 . Around the riser pipe 9 , one or more downpipes 10 are arranged on the outside, the upper openings of which in the pollutant treatment system 6 and the lower openings of which open into the free water above the immersion body 3 . The downpipe 10 can also be guided through the outer wall of the immersion body 3 , so that the lower opening opens into the immersion body 3 . For shallow water, the connection 2 can be made extremely short or can be integrated in the floating body 1 .

The device is designed in such a way that autonomous operation of the entire system is ensured, except for maintenance and control work. The device can be walked on. The energy supply (traditional, solar system or wind turbine) takes place directly or via land connection cables. The energy supply to the ejector 17 and the underwater pump 16 is ensured via an underwater cable 12 . The load or pollutant treatment is in the pollutant treatment system 6 by means of methods known per se, such as. B. made by filtration, flotation, precipitation, etc. The contaminants are biochemically broken down or the pollutants are eliminated and handed over to a suitable disposal container (container, disposal pontoon). This entire process is controlled by a process measurement control known per se.

The floating body 1 and the connection 2 and the diving body 3 are anchored and moved in a traditional manner. In the case of a flat treatment of the water bed, the entire device is moved very slowly horizontally via an external pulling device 10 . In addition, between the floating body 1 and the immersion body 3 , traction devices 13 ensure that the immersion body 3 is constantly carried along and the probes 19 in the sediment in the working position are also carried along.

The sediment treatment procedure is now as follows carried out: Starting from an exact water and Sediment analysis as well as general water and Basic water conditions become the target parameters for Treatment of the water set. Here u. a. also Determinations made whether a selective, partial or surface treatment of the subsoil takes place what largely due to the natural and local conditions is determined. The aim should be to use the procedure in places of greatest silt thickness. This can happen with favorable flow conditions due to dredging or Creation of so-called sediment traps can be achieved. Sediment traps are artificially created depressions in the Underground, in the use of a natural or the sediments are deliberately created collect and deposit. In addition to the sediment traps described are natural sediment accumulations in the subsurface particularly suitable for the application of the method.

The device is now driven over such sediment enrichment in the water and fixed there in a suitable manner. The immersion body 3 is lowered via the sediment. The probes 19 are then introduced into the sediment from their rest position in the immersion body 3 due to the effect of gravity. The introduction of the probes 19 into the sediment can be supported by simultaneous outflow of a water-air mixture from the nozzle-shaped ends of the probes 19 (flushing effect). The required supply air is supplied with the aid of the underwater pump 16 with ejector 17 arranged on the immersion body 3 via the supply air line 11 .

After the probes 19 have been introduced into the sediment, they are treated in the following process steps:

• - Oxygen-enriched water is introduced into the sediment via the probe 19 . For this purpose, the water pumped by the underwater pump 16 into the ejector 17 is mixed with air from the supply air line 7 . As a result of the introduction of the water-air mixture, the sediment is whirled up inside the immersion body 3 . This initiates the nitrification, ie the conversion of ammonium (NH₄) into nitrates. The period of nitrification is determined beforehand by measuring the nitrogen content in the sediment.
  In this first process step, the water-air mixture precipitants, such as. As calcium phosphate, iron sulfate or iron chloride sulfate can be added. These precipitants enter the supply air line 11 through a corresponding opening. This ensures that the phosphorus in the sediment is bound and is no longer available to the plants as a nutrient.
• After the nitrification has been completed, the agitated sediment is mixed with approximately oxygen-poor water in the immersion body 3 . For this purpose, the water is fed into the probes 19 via the underwater pump 16 without supply air. As a result of the introduction of this oxygen-poor water, a denitrification is initiated, ie the nitrate nitrogen is converted into air-like nitrogen. Due to the buoyancy swirl of the fine gas bubbles and the local pressure conditions in the immersion body 3 , an upward directed gas-water-Seston mixture stream is generated, which flows into the connection 2 . There, the biochemical reaction is continued in the riser pipe 9 in the mixing elements 15 and trickling filters 14 . Finally, this mixture flow opens into the pollutant treatment system 6 , where the nitrogen can escape into the atmosphere via the degassing pots.
  By a known measuring, control and regulating system, the load and pollutant concentration of the water is detected in the pollutant treatment system 6 and with known methods, such as. B. Filtration, flotation and precipitation, these eliminated from the water. The cleaned and oxygen-enriched water either reaches the water via the downpipe 10 or is returned to the immersion body 3 and the probe system in the sense of a circulatory process 5 .
  In this second process step, as already described in the first process step, precipitants can be added to the water-air mixture.
• - After completing the denitrification, the Water cycle precipitant to bind the im Sediment supplied to existing phosphorus.

The above three process steps are as long repeated until the sedimentation process is sufficient is completed. That is, until the top layer of the Sediments of about 20 cm thick in a layer with a significantly reduced nitrogen content is transferred and thus a barrier layer for the lower sediment layers to the surrounding water. Through this barrier layer avoided that nutrients from the lower sediment layers can be given to the water.

List of reference numbers

1 float
2 connection
3 immersion bodies
4 buoyancy bodies
5 utilities
6 Pollutant treatment plant
7 opening
8 degassing channel
9 riser pipe
10 downpipe
11 Supply air line
12 underwater cables
13 pulling device
14 trickling filter
15 mixing element
16 submersible pump
17 ejector
18 pulling device
19 probe
20 water bottom
21 pulling device

Claims (13)

1. A method for the treatment of eutrophicated surface waters with high silt thickness on the water bottom, characterized in that water or a water-gas mixture with or without a chemical metering is initiated in the open water in the sediment shielded from the free water until the Deprivation of nutrients from the sediment Such mineralization in an upper layer of the sediment causes the lower layers of the sediment to be separated from the water. 2. The method according to claim 1, characterized in that oxygen-enriched water for the introduction of a Nitrification is introduced into the sediment and after Complete the nitrification by mixing the whirled up sediments with almost no oxygen Water to initiate denitrification becomes. 3. The method according to claim 1, characterized in that oxygen-enriched water for the introduction of a Nitrification is introduced into the sediment and after Complete the nitrification by mixing the whirled up sediments with almost no oxygen Water to initiate denitrification is precipitant and after completion of the denitrification be added to the water cycle. 4. The method according to claim 1, characterized in that oxygen-enriched water for the introduction of a Nitrification is introduced into the sediment and Precipitating agents are added to the water cycle and after completion of the nitrification, a thorough mixing of the whirled up sediments with almost no oxygen Water to initiate denitrification becomes.   5. The method according to claim 1 and one of claims 2 to 4, characterized in that at the same time with the initiation of denitrification by the buoyancy of the fine gas bubbles and the local pressure conditions, an upward gas-water Seston mixture stream is generated in which the biochemical reaction continues, and the gas-water-Seston mixture flow finally flows into a load and pollutant treatment system ( 6 ), where the degassing takes place. 6. The method according to claim 5, characterized in that by measuring, controlling and regulating the load and 15 Pollutant concentration in the water recorded and with itself known methods the pollutants and pollutants from the water eliminated, at the same time the biochemical cleaning stages be finished and the cleaned and with oxygen enriched water either in the water or in the 20 circuit for sediment treatment is supplied. 7. A device for performing the method according to claim 1, characterized in that the device consists essentially of a floating body ( 1 ) and a diving body ( 3 ) 25, both of which can be flexibly adapted to different water depths and water levels connection ( 2 ) are connected. 8. The device according to claim 7, characterized in that the 30 floating body ( 1 ) with a pollutant treatment system ( 6 ) is connected. 9. The device according to claim 7, characterized in that the connection ( 2 ) is designed as a riser pipe ( 9 ). 10. The device according to claim 9, characterized in that in the compound ( 2 ) for continuing the biochemical reaction within the gas-water-Seston mixture, mixing elements ( 15 ) and trickling filter ( 14 ) are arranged one behind the other. 11. The device according to claim 9, characterized in that one or more downpipes ( 10 ) are arranged outside of the riser pipe ( 9 ), the upper opening in the pollutant treatment system ( 6 ) and the lower opening in the free water or in the immersion body ( 3 ) flow out. 12. The apparatus according to claim 7, characterized in that in the lower part of the immersion body ( 3 ) probes ( 19 ) which are movable in the sediment direction are arranged. 13. The apparatus according to claim 12, characterized in that the probes ( 19 ) are nozzle-shaped at the lower end.