Device and method for efficiently reducing iron ions in water

Abstract

The invention provides a device for increasing the gas content of liquid, a purification device for reducing iron ions in underground water and a filtering method, underground water is extracted and firstly passes through a pretreatment unit to remove large particles and suspended solids, then passes through a filter tank with a multi-layer porous filter bed, and water subjected to oxygenation flows into a sedimentation tank; the method comprises the following steps: oxidizing iron ions (Fe < 2 + >) in underground water to generate water-insoluble ferric oxide (Fe < 3 + >), and precipitating, thereby reducing the iron ions (Fe < 2 + >) in water to reach the drainage standard. The device is efficient, environmentally friendly, easy and convenient to operate and particularly suitable for the situation that large-area underground water pumping and discharging are needed.

Description

Technical Field

[0001] The invention relates to the technical field of groundwater purification, in particular to a filtering method for reducing iron ions in groundwater. Background Art

[0002] Groundwater is an important water resource in many regions and is widely used for drinking water, agricultural irrigation and industrial water. However, groundwater often contains a variety of impurities, among which iron ions (Fe2+ and Fe3+) are one of the common pollutants that need to be treated. The presence of iron ions in groundwater not only affects the sensory quality of water, such as color and taste, but also causes a series of problems during use, such as pipe scaling, equipment corrosion and stains. Long-term drinking of groundwater with excessive iron ions is also potentially harmful to human health. For some underground engineering construction, it is necessary to pump underground to control groundwater pressure and ensure engineering safety, such as deep foundation pit projects. If the underground is directly discharged, it will cause environmental pollution.

[0003] At present, the methods for reducing iron ions in groundwater mainly include oxidation precipitation, ion exchange, membrane separation and biological treatment. These methods have their own advantages and disadvantages, but they still face some challenges in practical application. For example, the oxidation precipitation method requires the addition of chemical agents, such as natural manganese sand, which has poor effects and may cause secondary pollution; although the ion exchange method has better effects, the regeneration of the resin is complicated and costly; the membrane separation method requires high-pressure operation, consumes a lot of energy and the membrane is prone to clogging; the biological treatment process is slow and has high requirements for environmental conditions. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a device for increasing the gas content of liquid, a purification device and a filtering method for reducing iron ions in groundwater. Groundwater extraction first passes through a pretreatment unit to remove large particles and suspended matter, and then passes through a filter tank with a multi-layer porous filter bed. The water after oxygenation flows into a sedimentation tank, and the iron ions (Fe2+) in the groundwater are oxidized to generate water-insoluble trivalent iron oxides (Fe3+), and precipitate, thereby reducing the iron ions (Fe2+) in the water to meet the drainage standard. The present invention is efficient, environmentally friendly, and easy to operate, and is particularly suitable for situations where large-area groundwater extraction and discharge are required.

[0005] The present invention provides a device for increasing the gas content of liquid, comprising a filter bed top plate, a filter bed middle partition plate, a filter bed bottom plate, a ventilation main panel, and a ventilation sub-panel. The device comprises at least one filter bed top plate, a filter bed middle partition plate, and a filter bed bottom plate arranged in sequence; the filter bed middle partition plate forms an acute angle with a horizontal plane with its starting point as the vertex; each filter bed middle partition plate is provided with a water leakage hole at its lower part for allowing liquid to pass through, and when there are multiple filter bed middle partition plates, adjacently arranged filter bed middle partition plates are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle partition plates in sequence;

[0006] The device comprises a plurality of ventilation main panels, for each ventilation main panel:

[0007] One end of the ventilation main panel is connected to the filter bed middle partition, and the other end is connected to the plate adjacent to the filter bed middle partition, and the plate is the filter bed top plate or the filter bed bottom plate or another filter bed middle partition; one end of a plurality of ventilation sub-panels is connected to the ventilation main panel, and the other end extends in the direction opposite to the liquid; the ventilation main panel and the ventilation sub-panels are internally connected to transport gas.

[0008] Preferably, the ventilation main panels are arranged to be inclined, and the inclination direction is: the lowest point of each ventilation main panel is closer to the oncoming water than the highest point thereof.

[0009] Preferably, the filter bed has a drainage hole only at the lowest point of the baffle.

[0010] Preferably, a plurality of water leakage holes allowing liquid to pass through are provided at different heights on the partition in the filter bed, and accordingly, the ventilation sub-panel forms an acute angle with the ventilation main panel above it to which it is connected, that is, it extends obliquely upward; when the liquid does not reach the lowest point of the partition in the filter bed and directly leaks down from the water leakage holes, the liquid will inevitably contact the ventilation sub-panel below wherever it passes.

[0011] The present invention also provides application of the device for increasing the gas content in liquid to reducing the iron ion concentration in water.

[0012] The present invention provides a purification device for reducing the iron ion concentration in water, the structure of which includes the above-mentioned device for increasing the gas content in liquid for water oxygenation. The structure of the device includes:

[0013] A pre-treatment unit, including a filter;

[0014] An oxygenation unit, comprising a ventilation main pipe and the above-mentioned device for increasing the gas content of the liquid;

[0015] The sedimentation tank unit includes sedimentation tank walls and filter patches arranged at intervals, each of the sedimentation tank walls is erected at the bottom of the sedimentation tank and forms a water flow gap with the top of the sedimentation tank, and each filter patch is suspended at the top of the sedimentation tank and forms a water flow gap with the bottom of the sedimentation tank, thereby guiding the water flow direction to rub the two sides of each filter patch in the forward direction, rather than just directly passing through the filter patch.

[0016] Preferably, a nonwoven geotextile is arranged on the surface of the filter patch.

[0017] On the other hand, the present invention provides a filtering method for efficiently reducing iron ions in groundwater, which is composed of a pumping unit, a pretreatment unit, an oxygenation unit, a sedimentation tank unit, a drainage unit, etc. The groundwater is extracted by the pumping unit and first passes through the pretreatment unit to remove large particles and suspended matter, and then passes through a device for increasing the gas content of the liquid, that is, an oxygenation unit with a multi-layer porous filter bed to increase the oxygen content in the water. The water after oxygenation flows into the sedimentation tank unit, and the iron ions (Fe2+) in the groundwater are oxidized to generate water-insoluble trivalent iron oxides (Fe3+), and precipitate, thereby reducing the iron ions (Fe2+) in the water. Finally, the water passes through the drainage unit and is discharged after monitoring to reach the discharge standard. The present invention has the advantages of low cost, large processing capacity and high efficiency.

[0018] The present invention provides a filtration method for efficiently reducing iron ions in groundwater. The core of the method is to utilize a multi-layer porous filter bed of an oxygenation unit to allow the extracted groundwater to fully contact with air, thereby efficiently oxidizing the iron ions and precipitating them in a sedimentation tank. The specific implementation includes the following steps:

[0019] Step 1: After groundwater is pumped out by a pumping unit, it flows into a pretreatment unit through a water inlet pipe. The pumping unit includes a pump and a water inlet pipe.

[0020] Step 2: After the water enters the pre-treatment unit, it is initially filtered by multiple layers of filters to reduce large particles and suspended solids. The pre-treated water flows into the aeration unit.

[0021] Step 3: After the water flows into the oxygenation unit, it flows through the multi-layer porous filter bed and is repeatedly aerated to increase the oxygen content in the water. The water after oxygenation flows into the sedimentation tank unit. The aeration process is to use an air compressor to pump air into the multi-layer porous filter bed, so that the water and air are repeatedly in contact. The air compressor is connected to the filter bed through a connecting pipe.

[0022] Step 4, the oxygen-injected water flows into the sedimentation tank through the pipeline, and the iron ions (Fe2+) in the water are more fully oxidized with the oxygen in the water, and trivalent iron oxide (Fe3+) is produced.

[0023] Step 5: The water after sedimentation passes through the drainage unit and is discharged after monitoring to meet the discharge standard. If it does not meet the standard, the groundwater treatment can meet the standard by adjusting the ventilation volume to increase oxygen, or increasing the flow path of the sedimentation tank unit to increase the sedimentation time.

[0024] Preferably, in the above method, the device for increasing the gas content of liquid as described in the present application comprises a multi-layer porous filter bed of a three-dimensional structure, which is composed of a top plate, a middle partition plate, a bottom plate, a ventilation main panel, and a ventilation sub-panel, and each plate has a water leakage hole. The top plate, the middle partition plate, and the bottom plate are connected by the ventilation main panel. The number of the middle partition plates can be increased or decreased as needed.

[0025] Preferably, the multi-layer porous filter bed has two types of vertical ventilation and horizontal ventilation. The vertical ventilation type is characterized in that the top plate, the middle partition plate, and the bottom plate are evenly provided with leakage holes, and the water flow can pass through the filter bed quickly and vertically, and the treatment efficiency is relatively high; the horizontal ventilation type is characterized in that the leakage holes of the top plate, the middle partition plate, and the bottom plate are only opened at the low position of the plate, and the water flow needs to flow through all the plate surfaces, so the ventilation is relatively sufficient.

[0026] Preferably, the top plate and the middle partition plate have a certain inclination angle so that water can flow on the plates; the ventilation main panel also has a certain inclination angle, and the inclination direction is consistent with the top plate and the middle partition plate, so that when water falls from the top plate and the middle partition plate, a larger area is caught by the ventilation main panel.

[0027] Preferably, the ventilation main panel is mounted with a ventilation sub-panel, which is characterized by being perpendicular to the ventilation main panel.

[0028] Preferably, the ventilation main panel and the ventilation sub-panel are composed of a hollow plywood, a ventilation main pipe, and a capillary tube. The surface of the plywood is provided with densely distributed ventilation panel holes. The capillary tube is connected to the ventilation main pipe, and the ventilation main pipe is connected to the ventilation connecting pipe. The capillary tube is provided with densely distributed capillary holes. The air passes through the connecting pipe, the ventilation main pipe, the capillary tube, and the capillary holes, and is blown out to the ventilation panel holes, and finally achieves repeated mixing with the water falling on the ventilation main panel and the ventilation sub-panel.

[0029] Preferably, the interior of the sedimentation tank unit of the device described in the present invention is made into a tortuous form to increase the path for groundwater to flow, allowing more time for the iron oxides (Fe3+) in the groundwater to settle.

[0030] Preferably, a porous filter patch is fixed on the wall of the sedimentation tank. The porous filter patch can further adsorb groundwater iron oxide (Fe3+). When there is too much sediment, the filter patch can be removed and replaced with a new one.

[0031] Preferably, the filter patch has a porous non-woven geotextile at the bottom and a plastic grid mesh at the top, both of which are bonded together. The non-woven geotextile provides a porous structure to filter sediments; the plastic grid mesh can store sediments to prevent the sediments from being washed away by water.

[0032] Preferably, the material of the multi-layer porous filter bed is selected from corrosion-resistant and wear-resistant ceramics or plastics to ensure the long-term stable operation of the device.

[0033] The present invention has the following technical effects:

[0034] 1. The present invention designs a three-dimensional multi-layer porous filter bed, which can fully allow water to contact with air, so that the oxygen content in the water is increased. The setting is simple, the process cost of treating groundwater is low, and the efficiency is high.

[0035] 2. The present invention sets a tortuous flow path and a filter patch on the sedimentation tank unit to increase the precipitation of iron oxide products. The filter patch is a reusable cloth and is corrosion-resistant. When the iron oxide product is precipitated to a certain extent, the geosynthetic cloth is taken out, and after drying, the precipitate can be separated from the geosynthetic cloth, thereby achieving the goal of reuse.

[0036] 3. The filter bed of the present invention is made of corrosion-resistant and wear-resistant ceramic or plastic, which is corrosion-resistant and increases the long-term service performance of the process equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A side view illustrating the processing flow.

[0038] Figure 2 This is a cross-sectional view of a vertically ventilated multi-layer porous filter bed.

[0039] Figure 3 It is a top view of the top plate, middle partition plate or bottom plate of a vertical ventilation filter bed.

[0040] Figure 4 This is a cross-sectional view of a transversely ventilated multi-layer porous filter bed.

[0041] Figure 5 It is a top view of the top plate, middle partition plate or bottom plate of the transverse ventilation filter bed.

[0042] Figure 6 This is a side view of the ventilation main panel.

[0043] Figure 7 Side view of the ventilation sub-panel.

[0044] Figure 8 This is a cross-sectional view of the ventilation main / sub panel.

[0045] Fig. 9 This is a cross-sectional view of the ventilation pipeline system.

[0046] Fig.10 This is a cross-sectional view of a sedimentation tank unit.

[0047] Fig.11 This is a cross-sectional view of the filter patch.

[0048] The reference numerals in the figure are: 1-ground surface; 2-water flow direction; 20-pumping unit; 21-pumping machine; 22-water inlet pipe; 30-pretreatment unit; 31-filter screen; 40-oxygenation unit; 41-ventilation main pipe; 42-multi-layer porous filter bed; 43-connecting pipe; 44-air booster; 50-sedimentation tank unit; 51-sedimentation tank wall; 52-filter screen patch; 53-non-woven geotextile; 54-plastic grid net; 60-drainage unit; 61-outlet pipe; 62-iron content online monitoring unit; 421-filter bed top plate; 422-filter bed middle partition; 423-filter bed bottom plate; 424-ventilation main panel; 425-ventilation secondary panel; 426-circular leakage hole; 427-ventilation panel hole; 428-capillary; 429-capillary hole; 430-plywood; 431-strip leakage hole. Specific embodiments

[0049] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0050] Example 1

[0051] like Figure 2 and Figure 4 As shown, it is a device for increasing the gas content of liquid, comprising a filter bed top plate 421, a filter bed middle partition plate 422, a filter bed bottom plate 423, a ventilation main panel 424, and a ventilation sub-panel 425. The device comprises at least one filter bed top plate 421, a filter bed middle partition plate 422, and a filter bed bottom plate 423 arranged in sequence; the filter bed middle partition plate 422 forms an acute angle with the horizontal plane with its starting point as the vertex; each filter bed middle partition plate 422 is provided with a water leakage hole at its lower part to allow liquid to pass through, and when there are multiple filter bed middle partition plates 422, the adjacently arranged filter bed middle partition plates 422 are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle partition plates 422 in sequence;

[0052] The device comprises a plurality of ventilation main panels 424, for each ventilation main panel 424:

[0053] One end of the ventilation main panel 424 is connected to the filter bed middle partition 422, and the other end is connected to the plate adjacent to the filter bed middle partition 422, and the plate is the filter bed top plate 421 or the filter bed bottom plate 423 or another filter bed middle partition 422; one end of a plurality of ventilation sub-panels 425 is connected to the ventilation main panel 424, and the other end extends in the direction opposite to the liquid; the ventilation main panel 424 and the ventilation sub-panel 425 are internally connected to transport gas.

[0054] like Figure 2 and Figure 4 As shown, the ventilation main panels 424 are tilted, and the tilting direction is: the lowest point of each ventilation main panel 424 is closer to the oncoming water than the highest point thereof.

[0055] like Figure 6 The figure shows a side view of the ventilation main panel, which contains multiple ventilation main pipes, such as Figure 7-9 As shown, the ventilation main pipe 41 is connected to a plurality of capillary tubes 428, each capillary tube is connected to a plurality of capillary holes 429, and the ventilation panel contains a plurality of ventilation panel holes 427 to allow water to flow through. The internal structure of the ventilation sub-panel 425 is similar to that of the ventilation main panel 424.

[0056] In some cases, such as Figure 4-5 The partition plate 422 in the filter bed shown has a water leakage hole only at the lowest point.

[0057] In other cases, such as Figure 2-3 As shown, a plurality of water leakage holes for allowing liquid to pass through are provided at different heights on the partition plate 422 in the filter bed, and accordingly, the ventilation sub-panel 425 forms an acute angle with the ventilation main panel 424 above it is connected, that is, it extends obliquely upward; when the liquid does not reach the lowest point of the partition plate 422 in the filter bed and directly leaks from the water leakage holes, the liquid will inevitably contact the ventilation sub-panel 425 below wherever it passes.

[0058] Example 2

[0059] like Figure 1 As shown, the present invention provides a purification device for reducing the iron ion concentration in water, including the device for increasing the gas content in liquid as described in Example 1 for oxygenating water. The sequentially connected structures include:

[0060] A pre-treatment unit 30, comprising a filter screen 31;

[0061] The oxygen enrichment unit 40 comprises a ventilation main pipe 41 and the device for increasing the gas content in liquid as claimed in claim 1.

[0062] like Fig.10As shown, the sedimentation tank unit 50 includes sedimentation tank walls 51 and filter patches 52 arranged at intervals, each of which is erected at the bottom of the sedimentation tank and forms a water flow gap with the top of the sedimentation tank, and each of which is suspended at the top of the sedimentation tank and forms a water flow gap with the bottom of the sedimentation tank, thereby guiding the water flow to rub against the two sides of each filter patch 52 in the forward direction, rather than just directly passing through the filter patch 52. Fig.11 As shown, the non-woven geotextile is arranged on the surface of the filter patch 52 .

[0063] Example 3

[0064] In this embodiment, during the excavation of a foundation pit project, it is necessary to pump groundwater to reduce water pressure and ensure safe excavation of the foundation pit. The groundwater test results show that the iron ion exceeds the standard and cannot be directly discharged into the surrounding rivers. In this embodiment, since the groundwater requires a large amount of precipitation, the present invention is used to reduce the iron ion concentration of groundwater to meet the discharge standard. In this embodiment, the plane dimensions of the pools of the pre-pretreatment unit and the oxygenation unit are 3m×3m and the depth is 2m; the plane dimensions of the sedimentation tank of the sedimentation tank unit are 5m×5m and the depth is also 2m. Three layers of filter screens are installed in the outflow pipe of the pretreatment tank; a filter bed made of multi-layer porous plastic is installed in the filter tank. Due to the large processing capacity and high processing standards, the filter bed is a transverse ventilation type, with 5 layers of middle partitions, the plane dimensions are consistent with the inner diameter of the pool of the oxygenation unit, and the thickness is 1m; filter screen patches are installed on the side walls and bottom of the sedimentation tank. In order to reduce the iron ion content, the following steps are mainly followed:

[0065] Step 1: The groundwater is pumped out from the drainage wells around the foundation pit by a pump and flows into the pretreatment unit through the water inlet pipe.

[0066] Step 2: After the water enters the pretreatment unit, it is initially filtered by three layers of filters to reduce large particles and suspended solids. The pretreated water flows into the aeration unit.

[0067] Step 3: After the water flows into the oxygenation unit, it flows through the multi-layer porous filter bed and is repeatedly aerated to increase the oxygen content in the water. The water after oxygenation flows into the sedimentation tank unit. The aeration process is to use an air compressor to pump air into the multi-layer porous filter bed so that the water and air are repeatedly in contact. The air compressor is connected to the filter bed through a connecting pipe. The boosting pressure of the air compressor is 1.5 bar.

[0068] Step 4, the oxygen-injected water flows into the sedimentation tank through the pipeline, and the iron ions Fe2+ in the water are more fully oxidized with the oxygen in the water, and trivalent iron oxide Fe3+ is produced and deposited.

[0069] Step 5, the sedimented water passes through the drainage unit, and the iron content online monitoring unit dynamically tests the iron ion content in the water. When the iron ion content is less than or equal to 0.3 mg / L, the groundwater is discharged.

[0070] The specific positions of the various parts and their interconnected relationships can be clearly seen through the accompanying drawings. These illustrations provide visual support for the specific embodiments of the present invention and are helpful for understanding its technical principles and practical applications.

[0071] Based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

Claims

1. A device for increasing the gas content of a liquid, comprising a filter bed top plate (421), a filter bed middle partition plate (422), a filter bed bottom plate (423), a ventilation main panel (424), and a ventilation sub-panel (425), characterized in that: The device comprises at least one filter bed top plate (421), a filter bed middle partition plate (422), and a filter bed bottom plate (423) arranged in sequence; the filter bed middle partition plate (422) forms an acute angle with a horizontal plane with its starting point as the vertex; each filter bed middle partition plate (422) is provided with a water leakage hole at its lower part to allow liquid to pass through; when there are multiple filter bed middle partition plates (422), the adjacently arranged filter bed middle partition plates (422) are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle partition plates (422) in sequence; The device comprises a plurality of ventilation main panels (424), for each ventilation main panel (424): One end of the ventilation main panel (424) is connected to the filter bed middle partition (422), and the other end is connected to a plate adjacent to the filter bed middle partition (422), wherein the plate is a filter bed top plate (421) or a filter bed bottom plate (423) or another filter bed middle partition (422); one end of a plurality of ventilation sub-panels (425) is connected to the ventilation main panel (424), and the other end extends in a direction opposite to the liquid; the ventilation main panel (424) and the ventilation sub-panels (425) are internally connected to transport gas.

2. The device according to claim 1, characterized in that The ventilation main panels (424) are arranged to be inclined, and the inclination direction is such that the lowest point of each ventilation main panel (424) is closer to the oncoming water than the highest point thereof.

3. The device according to claim 1, characterized in that The filter bed partition plate (422) has a water leakage hole only at the lowest point.

4. The device according to claim 2, characterized in that A plurality of water leakage holes for allowing liquid to pass through are provided at different heights on the filter bed partition (422), and accordingly, the ventilation sub-panel (425) forms an acute angle with the ventilation main panel (424) connected thereto, that is, extends obliquely upward; when the liquid does not reach the lowest point of the filter bed partition (422) but directly leaks from the water leakage holes, the liquid will inevitably contact the ventilation sub-panel (425) below where it passes.

5. Use of the device for increasing the gas content in liquid according to any one of claims 1 to 4 in reducing the iron ion concentration in water.

6. A purification device for reducing the concentration of iron ions in water, characterized in that: The device for increasing the gas content in liquid according to any one of claims 1 to 4 is used for oxygenating water.

7. The purification device according to claim 6, characterized in that: Including in order: A pre-treatment unit (30) comprising a filter (31); An oxygenation unit (40) comprising a ventilation main pipe (41) and a device for increasing the gas content of a liquid according to any one of claims 1 to 4; The sedimentation tank unit (50) comprises sedimentation tank walls (51) and filter patches (52) arranged at intervals, wherein each sedimentation tank wall (51) is erected at the bottom of the sedimentation tank and forms a water flow gap with the top of the sedimentation tank, and each filter patch (52) is suspended at the top of the sedimentation tank and forms a water flow gap with the bottom of the sedimentation tank, thereby guiding the water flow direction to rub against the two sides of each filter patch (52) in the forward direction, rather than just directly passing through the filter patch (52).

8. The purification device according to claim 7, characterized in that: The non-woven geotextile is arranged on the surface of the filter patch (52).

9. A method for reducing the iron ion content in water using the purification device according to any one of claims 6 to 8, comprising the following steps: Step 1, pumping water out of the ground; Step 2, passing the water to be treated into a pretreatment unit and filtering it through a filter; Step 3, after the water flows into the oxygenation unit, it flows through the multi-layer porous filter bed and is repeatedly aerated to increase the oxygen content in the water; the water after oxygenation flows into the sedimentation tank unit; the aeration is to use an air compressor to pump air into the multi-layer porous filter bed so that the water and the air are repeatedly in contact; Step 4, the oxygen-injected water flows into the sedimentation tank through the pipeline, and the iron ions (Fe2+) in the water are more fully oxidized with the oxygen in the water, and trivalent iron oxide (Fe3+) is produced.

Images