KR20070051849A - Method and apparatus for the purification of ground water - Google Patents

Abstract

The present invention relates to a method for respectively reducing the content of metals, metalloids, nitrates and nitrites in raw water flowing through accompanying (1), thereby including metabolites of oxygen, oxygen-releasing substances, naturally occurring microorganisms or Or water comprising denitrification organisms and / or substrates is thus sometimes introduced into the head 1 through a plurality of satellite wells 2 arranged around the at least one extraction well 3 for purification water. Water containing oxygen and / or oxygen-releasing substrates or metabolites or denitrifying organisms and / or substrates of naturally-occurring microorganisms is distributed vertically and uniformly into the head (1), and the water to be purified is a horizontally aligned feedwater. Feeding into the well by pipe 5 and extraction of the purified water from the at least one extraction well 3 generates a significant sound pressure around the at least one extraction well. The invention also relates to an apparatus for carrying out the method and a satellite well to be used in the apparatus.

Groundwater, purification

Description

Groundwater purification method and apparatus {METHOD AND APPARATUS FOR THE PURIFICATION OF GROUND WATER}

The present invention relates to a method for reducing the content of metals, metalloids, nitrates or nitrites in groundwater, artificial groundwater or surface water penetrated into the surface water according to the preamble of claim 1. The invention also relates to an apparatus according to claim 8 for carrying out the method.

In the past, water requiring treatment and purification to remove iron and manganese has been treated in water treatment plants by adding oxygen to the water. This caused precipitation of impurities, which were filtered off in purified water. Oxygen is typically added in the form of pure oxygen or by aeration of water through the use of a cascade aerator. Because of the relatively low concentration of oxygen required to precipitate metal ions from the solution, metal iron and manganese were precipitated through the filtration process, where the filter comprises one or more sand layers through which water passes. Sand layers acting as filter materials often have to be regenerated to increase the removal of precipitated metal ions of manganese and iron, thus increasing the equipment investment and operating costs for such a purification plant.

Alternatively, groundwater has been purified in situ as described in Swedish Patent Specification 6903544-2. Water containing oxygen or oxygen-releasing material was intermittently introduced into the aquifer through a plurality of satellite wells or satellite pipes arranged at predetermined intervals and surrounding the feed well or feed pipe. Oxidized water entering the aquifer from this mantle increases the chemical and metabolic adsorption, oxidation and precipitation of the compounds in the existing subterranean layer, thereby creating a suitable environment for the growth of certain microorganisms using the underground layer as a reaction and filtration medium. Microorganisms used are often organisms that are primarily active in the region produced between oxidative and reducing conditions. Water containing oxygen or oxygen-releasing material was added intermittently over a period of approximately 24 hours. During the addition of water containing oxidized water or oxygen-releasing material, the feed well is fed to the purification water because the simultaneous use of the feed well and the satellite well will cause sluggish filtration or its operational disruption, which will lead to a deterioration of the quality of the water. Cannot be used. In order to supply water on a continuous basis, suitable means for the storage of two or more feed wells or storage are required to remedy the disadvantages such that the recovery of the purified water can be alternated between at least two wells or between the well and the storage means. come. If necessary, regeneration was performed in the dormant feed wells or wells while recovering the purified water from the alternate source.

When water is recovered from a single feed well and transferred to a satellite well or to multiple satellite wells to allow for concurrent use of the feed well, the flow pattern of the replenished water is generally the pattern of water flow to be purified. Similar to When this general similar flow pattern is established, a discontinuous radioactive tendency develops without purification between the satellite wells and the feed wells. This gradually reduces the operability of the feed well due to the precipitation of iron and manganese, and represents the largest portion in a smaller portion of the aquifer close to the feed well. This problem does not arise when using two or more feed wells as described above, and by altering the recovery of purified water between the feed wells and thereby distributing sediment over most of the aquifer.

In order to eliminate the drawbacks due to the discontinuous supply of water, another alternative to groundwater purification in phosphorus drilling is described in Swedish patent specification 8206393-4. The advantage of this invention is that no need for two or more feed wells is required, and the purified water is continuously pumped from a single feed means by generating a flow pattern that is approximately perpendicular to the flow pattern of water to be purified between the satellite wells. Is that. In this way, the columnar purge pattern appears at a sufficient distance from the feed wells that distribute the sediment over most of the aquifer to allow the feed well's operability to be maintained.

As used herein, the term "satellite well" is used to indicate that the treated water will be introduced into a filter, well, aquifer or similar purification or filtration system for such water to be purified. However, it can be understood that "satellite wells" are also used to recover water for ingress into other satellite wells. Representative examples of satellite wells include wells, pipes, hoses, tubes, and similar devices.

Conditioned water during operation is fed to at least one but not all satellite well, and at the same time as the inflow, the water is at least one to generate a purge zone for adsorption, conversion, oxidation, precipitation or volatilization of contaminants. Is drained from the satellite wells. In particular, water conditioned with oxidizing agents or other advantageous additives is used to reduce the concentration of impurities in untreated water, thereby "purifying" the water. Feeding the conditioned water to the satellite well in this way prevents congestion of the supply means and creates a purification or filtration zone at a distance far enough from the supply means to maintain proper flow of the supply means through the purification zone. The water to the satellite well will consist of conditioned water drained from at least one other satellite well and, if desired, also part of the purified water drained from the supply means.

By exchanging a number of satellite wells into which conditioned water has flowed in, and alternating satellite wells from which the water has been recovered, the user can best utilize the contaminant settling purification area. Two or more multiple satellite wells in this system will be used depending on the size of the purification system, hydrogeological conditions, biochemical conditions, concentration of impurities in the water, and the like. Conditioned water will enter the satellite well for a predetermined period of time, ranging from hours to days or longer.

The method according to Swedish patent specification 8206393-4 also allows for the continuous filtration and purification of groundwater and surface water using basin, in which a filter of naturally occurring or artificial material is contained and used. For example, for the mantle surface the soil will be excavated to form an attendant-shaped hole and a seal layer of clay, concrete, plastic, water-resistant cloth or the like will be applied to the mantle surface to form an inner wall. . Satellite wells for the entry of conditioned water are located inside the mantle in the head, and the head is filled with filter material such as sand. The supply means will be located at the center of the head; Satellite wells for the inflow of treated water are characterized by the inlet of conditioned water into a purification system through a number of satellite wells, the extraction of water through the means of extraction and supply of water through at least one satellite well, and the continuous recovery of purified water through the means of supply. To be enabled, it is arranged between the mantle and the center of the head, around the inner circumference of the outer surface of the head inner wall. In artificial aquifers, water is sometimes drained from at least one satellite well, conditioned and further introduced into at least one other satellite well. Alternating the satellite wells used for resupply and the satellite wells used for water recovery in this way effectively shifts the purge zone used for sedimentation of contaminants.

PCT WO02 / 48469 describes means and methods for the purification of water, and they can also be used in artificial aquifers, for example enclosed with inert materials. In this description, tensioning the cloth relative to the surrounding soil is said to be arranged below the soil surface, meaning that the top portion is open to air. The same arrangement also applies to Swedish patent specification 8206393-4. This will result in flooding of the material and flue deposits in the accompanying due to the high water pressure generated by the penetration of raw water in the accompanying and resupply to the satellite wells.

3 shows a computer simulation of the problem of high water pressure, which indicates that a pressure equal to overload of 4 meters or more will be required to produce sufficient back pressure against the high water pressure spread in known devices. As can be seen in FIG. 4, even with 4 meters of overload, there is still about 1.3 meters of overpressure.

Purpose of the Invention

It is an object of the present invention to eliminate the above-mentioned disadvantages and to allow for the purification of raw water in a continuous and cost-effective manner.

Accordingly, the present invention reduces the content of metals, metalloids, nitrates and nitrites respectively in groundwater, artificial groundwater, i.e. filtered surface water, or surface water flowing through accompanying naturally occurring filtration material, whereby the metal or quasi Oxygen or oxygen-releasing substances when reducing the metal content, and / or water containing metabolic reactants of naturally occurring microorganisms, and denitrifying organisms and / or substrates when reducing the content of nitrates and nitrites. Water is thus sometimes introduced into the head through a plurality of injection wells arranged around at least one extraction well for the purified water. The method is characterized in that the water comprising metabolic or denitrifying organisms and / or substrates of oxygen or oxygen-releasing materials and / or naturally occurring microorganisms is uniformly distributed vertically with the accompanying, and the water for purification is arranged horizontally. And supplied with condensed water through the water supply pipe and the extraction of the purified water from the at least one extraction well generates a significant negative pressure around the at least one extraction well.

According to a preferred embodiment of the method, the sound pressure around the at least one extraction well is on the scale of about 1 meter water head.

According to another preferred embodiment of the method, the extraction of the purified water from the extraction well allows the water pressure of both the feed pipe and the inlet pipe to be reduced to more than half the pressure present elsewhere in the feed and inlet pipes.

The invention also reduces the content of metals, metalloids, nitrates and nitrites, respectively, in groundwater, artificial groundwater, i.e. filtered surface water, or surface water flowing through naturally-occurring filtration material, and thus metal or metalloids. Water containing oxygen or oxygen-releasing substances and / or metabolites of naturally occurring microorganisms in the case of reducing the content of and water containing denitrifying organisms and / or substrates in the case of reducing the content of nitrates and nitrites. This therefore relates to a device which is sometimes introduced into the water through a plurality of injection wells arranged around at least one extraction well for the purified water. The device is characterized in that the seal is weld-sealed by a material impermeable to air and water and that all inlets and outlets through the material are impermeable to air and water.

According to a preferred embodiment of the apparatus, the satellite well comprises at least one inlet pipe and at least one extraction pipe and the inlet and outlet pipes have a region of these holes or gaps to compensate for the increased hydraulic pressure in the vertical direction. As a gap or a hole is provided.

By way of non-limiting example the invention will be described with reference to the accompanying drawings.

1 is a schematic side view of an apparatus according to a method for purifying raw water.

FIG. 2 is provided with a central extraction well and a plurality of satellite wells arranged around the extraction well, wherein the feed pipes and pipes for the penetration of raw water are represented by dashed lines and the overload of the surface is removed. It is a schematic view from above of the device according to FIG.

3 is a computer simulation of the distribution of pressure head in an apparatus for the purification of raw water according to the known art.

4 is a computer simulation of the distribution of pressure head sealed and unsealed for purification of raw water.

5 is a computer simulation of the distribution of a hermetically welded apparatus for purifying raw water according to the present invention.

6 is a final view of a satellite well used in the apparatus according to the invention.

7 is a partial side cross-sectional view of the satellite well of FIG. 6.

1 is an accompanying or artificial aquifer 1, provided with a cavity in the ground and containing a naturally occurring filtration material such as sand, or other suitable material (not shown), a plurality of injection / satellite wells 2, Raw water supply pipe 4 for supplying water from an extraction well 3, for example, a groundwater well (not shown) for supplying a horizontally arranged supply means or a water supply pipe 5, and the raw water supply. A device according to the invention is shown in a preferred embodiment for reducing the content of metals, metalloids, nitrates and nitrites in raw water, comprising a well 6 for possible cleaning of the pipe 4. The accompaniment 1 is an enclosed welded accompaniment 1 that is entirely surrounded by a material that is impermeable to air and water, for example rubber and / or plastics material. This also applies to the uppermost part of the accompanying (1). In addition, all inlets and outlets of pipes, cables and the like provided through the material 11 are made impermeable to air and water. In FIG. 1, the ground is marked 12.

In the embodiment shown, the accompaniment is covered by an overload of approximately 1 meter thick.

As can be seen in FIG. 2, in certain embodiments the device has the form of a square head 1, but it is clear that the head may have any other shape, such as circular or rectangular.

In the embodiment shown, eight satellite wells (2) and one extraction well (3) are arranged in the head (1). The raw water supply pipe 4, shown by the dotted line, is connected to at least one water supply pipe 5 arranged parallel to each side of the head 1. In addition, the respective satellite wells 2 are connected by means for oxidizing the water taken from the well 2 and the water is preferably returned to the well 2 after being oxidized and injected into the head 1.

In the device according to the invention, the satellite well 2 and the extraction well 3 are arranged such that the water is evenly distributed in the vertical direction of the head, especially when water is injected and / or pumped out of the head 1. . More precisely, as can be seen in FIGS. 6 and 7, in a preferred embodiment of the apparatus, the satellite well 2 has at least one extraction pipe 7 and at least one injection pipe separated by a separating means 9. (8) (in the embodiment shown two injection pipes and two extraction pipes). The extraction pipe 7 and the injection pipe 8 have an area of openings in the form of perforations or gaps 10 or holes made in any other way in the pipe wall of the pipes 7, 8 with respect to the surrounding material, increasing in the vertical direction. It is designed as a way to compensate the water pressure. The extraction pipe 7 thus has an area of opening whose horizontal portion is inversely proportional to the increased head pressure in the vertical direction, so that the flow of extracted water is distributed evenly along the entire covering surface of the pipe. Otherwise most of the water will come from the deeper part of the well with the highest water pressure. In the same way, the injection pipe 8 has an area of openings in which any horizontal part is inversely proportional to the increased pressure of the head in the vertical direction, so that the water injected therein is in most cases the most In order to avoid leaving the injection pipe 8 in the upper part, it is evenly distributed along the entire covering surface of the pipe. The extraction and injection pipes 7, 8 can be made as separate pipes or can be separated by separation means 9, as shown in FIG. 7.

Moreover, the design of the satellite well, ie the extraction pipe 7 and the injection pipe 8 shown in FIG. 7, can be used with devices used for the purification of groundwater, artificial groundwater, ie filtered surface water, or phosphorus drilling surface water. It is clear to the skilled workers.

At the beginning of the process according to the invention, the accompanies 1 filled with filter material are entirely filled with water. Pumping of water from the extraction well 3 begins and continues so that the water level around the well 3 is about 1 meter below the starting level. And the water is fed to the feed pipe 5 arranged horizontally through the raw water supply pipe 4, to a total volume corresponding to the volume taken through the extraction well 3, whereby the water supply 1 in FIG. Distribution of hydraulic pressure, as shown in FIG. If no further measurements are taken, the natural route will omit the drop in water level around the extraction well (3), and a large water pressure will occur in the periphery of the head (1) resulting in the above-mentioned flooding and destruction of the filter material. Will bring. In order to prevent this, it is required to automatically adjust the inflow and outflow of water so that the degradation around the extraction well 3 is maintained.

According to the invention, the greatly increased pressure in the horizontal feed pipe 5 and the inlet pipe 8 is controlled by pumping water from the extraction well 3, in this way the pressure to be replenished in the pipe in other cases. Is reduced by about half. A special method of pumping, which requires an adjustment and maintenance device (not shown), in a preferred embodiment is a high sound pressure around the central extraction well 3 corresponding to about one meter head below the impermeable material in the ground plane of the head 1. It is designed in such a way that it is always pervasive. See FIG. 5.

Thus, according to the present invention, the overpressure under the impermeable material is compensated by the overload of a suitable thickness above the enclosed (1), since the water can no longer be raised than for the impermeable material. The pressure to be generated is shown in FIG. 5 and as will be observed they will be up to about 0.5 meter heads. By providing the entrainment of impermeable material 11 extending around the entire enclosement 1, the purified water is also separated from impurities that may be present in the surrounding soil and air.

When oxygen is added through the aeration, it is done in a manner that allows water to circulate out of the enclosed head 1 through an aeration system (not shown). This aeration system will be common to the injection and extraction pipes 8, 7 arranged around the extraction well 3. Water from the extraction pipe 7 is aerated with a common device (not shown), and certain non-aeration is made in a small accompaniment (not shown), and free bubbles will leak into the ambient air. In small heads the water is evenly distributed by pumping it through the valve into the inlet pipe 8.

Moreover, oxidants include microorganisms and all other compositions, as well as water soluble chemicals and gases, and will cause oxidation of impurities or contaminants. When the present invention is used to purify groundwater or to purify raw water using the techniques described above, it is also possible to use metabolic reactions of naturally occurring microorganisms as the mechanism by which precipitation or degradation of contaminants occurs. For example, microorganisms Crenothrix, Leptothrix and Gallionella have been used to cause oxidation and / or precipitation of contaminant iron and manganese in the presence of oxygen. Similarly, by conditioning with various reagents, such as methane or nutrients to replenish water, heterotrophic microorganisms will be induced to oxidize or metabolize various organic compounds that contaminate water. Thus, naturally occurring microorganisms will be provided in part as a means for purifying contaminated water using the present invention.

Since the porosity of the filtration material in the accompanying 1 is dimensioned to a life of preferably 100 years or more, before the stagnation of the filtration material leads to a reduction in pumping capacity in the extraction well 3, It does not need to be exchanged or reproduced for removal of precipitated iron and manganese or other metals or metalloids.

The attendant 1 shown in FIG. 1 can be combined with one or more similar attendant (s), whereby the injection and extraction pipes to be adjacent to each other are joined to form a common injection and extraction pipe.

Although the invention has been described above for the removal of iron and manganese, it is apparent to the skilled artisan that it can also be used for the removal of other metals or metalloids such as lead and arsenic.

Since the accompanying / artificial aquifer 1 according to the invention forms a closed system, it is also possible to use a process which requires the absence of oxygen. The injection pipe 8 will be used for the injection of nutrients necessary for the microorganisms present in anoxic conditions, instead of the injection of oxidized water. Such nutrients will consist of low molecular weight substances such as phosphates or alcohols. In such a process nitrates and nitrites are converted to nitrogen made using denitrification organisms, and nitrogen will follow the water taken from the extraction well (3). This water must be aerated to restore the equilibrium between nitrogen and oxygen in the composition of the air.

In this case, it is desirable to simultaneously remove both metal, metalloid and nitrate and nitrite from raw water, respectively, which can be done in at least two stages, whereby the nitrate and nitrite are at least one first source of nutrients other than oxygen. It is first removed from the head comprising one or a plurality of individually arranged modules by feeding the second module (s) and then supplying the oxygen or oxygen-releasing material to at least one second module. Water from the first module (s) is fed to the second module (s) without any intermediate treatment. The two stages purification of the raw water can of course also take place separately in the arrangements 1.

Claims (12)

Groundwater, artificial groundwater, ie filtered surface water, or surface water flowing through the basin (1) containing naturally occurring filtration material, respectively, reduce the content of metals, metalloids, nitrates and nitrites, thereby reducing metal or quasi When reducing the content of metals, water containing oxygen or oxygen-releasing substances and / or metabolites of naturally occurring microorganisms, and when reducing the content of nitrates and nitrites, water containing denitrifying organisms and / or substrates The metabolism of the oxygen or oxygen-releasing substrate and / or naturally occurring microorganisms is thus sometimes introduced into the head (1) via a plurality of satellite wells (2) arranged around one or more purification wells (3) Water containing the reactants or denitrification organisms and / or substrates is vertically and uniformly distributed to the accompanying (1) and purified The vaginal water is supplied with water by horizontally arranged feed pipes 5 and the extraction of purified water from the one or more extraction wells 3 causes a significant negative pressure to be generated around the one or more extraction wells. How to feature. The method of claim 1, wherein the sound pressure around the one or more extraction wells (3) is similar in size to a water head of about one meter. 2. The extraction of purified water from the extraction well (3) according to claim 1, wherein the water pressure of both the water supply pipe (5) and the satellite well (2) is reduced if the pumping is not carried out. In which the pressure is reduced to more than half of the pressure present otherwise. The method of claim 1, wherein the method is carried out in at least two stages and entails separating into two or more individually arranged modules, whereby in the first stage the content of nitrates and nitrites is reduced to the first module. And in the second step the content of metals and metalloids is reduced to the second module and the water is fed between two or more modules without any intermediate treatment. The method according to any one of claims 1 to 4, wherein the metal and metalloid to be removed from the raw water are selected from the group consisting of iron, manganese, lead and arsenic. The method of claim 1 wherein the method is used to reduce only the content of nitrates and nitrites. The method of claim 1 wherein the method is used to reduce only the content of metals and metalloids. Groundwater, artificial groundwater, ie filtered surface water, or surface water flowing through the basin (1) containing naturally occurring filtration material, respectively, reduce the content of metals, metalloids, nitrates and nitrites, and thus metal or metalloids To reduce the content of water containing oxygen or oxygen-releasing material and / or metabolites of naturally occurring microorganisms, and to reduce the content of nitrates and nitrites, water containing denitrifying organisms and / or substrates The device is thus sometimes introduced into the head 1 through a plurality of satellite wells 2 arranged around one or more extraction wells 3 for purification water, the head 1 being impermeable to air and water. All inlets and outlets welded and sealed by the material (11) and through the material (11) are impermeable to air and water. 9. The satellite well (2) comprises at least one injection pipe (8) and at least one extraction pipe (7) and the injection pipe (8) and the extraction pipe (7) are provided with gaps or holes. And the area of these gaps or holes (10) compensates for the increased hydraulic pressure in the vertical direction. 9. The process according to claim 8, wherein when the reduction of the content of metals, metalloids, nitrates and nitrites is carried out in at least two stages, the accompanying (1) comprises at least two individually arranged modules and the water without any intermediate treatment. The device characterized in that the water supply. 9. The apparatus of claim 8, wherein the metals and metalloids to be removed from the raw water are selected from the group consisting of iron, manganese, lead and arsenic. Satellite wells to be used in the device according to any one of claims 8 to 11 or in a known device for phosphorus drilling of groundwater, artificial groundwater, ie filtered surface water, or surface water, said satellite well (2) Comprises at least one injection pipe 8 and at least one extraction well 7 and the injection pipe 8 and the extraction pipe 7 have gaps or holes 10, these gaps or holes 10 The area of the satellite well is characterized by compensating for the increased water pressure in the vertical direction.

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