A device and method for efficiently reducing iron ions in water

Abstract

The present invention provides a device for increasing the gas content of a liquid, a purification device for reducing the iron ion content in groundwater, and a filtration method. Groundwater extraction first 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. The oxygenated water flows into a sedimentation tank, where the ferrous ions in the groundwater are oxidized to form water-insoluble ferric oxides, which are then precipitated. This reduces the ferrous ion content in the water to meet drainage standards. The present invention is efficient, environmentally friendly, and easy to operate, making it particularly suitable for situations where large-scale groundwater extraction and discharge are required.

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 (Fe 2+ and Fe 3+ ) is a common pollutant that requires focused treatment. The presence of iron ions in groundwater not only affects the sensory qualities of the 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 consumption of groundwater with excessive iron ions is also potentially harmful to human health. For some underground construction projects, such as deep foundation pits, underground pumping is required to control groundwater pressure and ensure project safety. Direct discharge of this pumped water will pollute the environment.

[0003] Currently, methods for reducing iron ions in groundwater primarily include oxidation precipitation, ion exchange, membrane separation, and biological treatment. Each of these methods has its advantages and disadvantages, but they still face challenges in practical application. For example, oxidation precipitation requires the addition of chemical agents, such as natural manganese sand, which is ineffective and can cause secondary pollution. While ion exchange is effective, the resin regeneration process is complex and costly. Membrane separation requires high pressure, consumes significant energy, and is prone to membrane clogging. Biological treatment is slow and requires strict 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 for reducing the iron ions in groundwater and a filtration method. The groundwater is first extracted 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 to remove ferrous ions (Fe 2+ ) oxidation reaction to generate water-insoluble trivalent iron oxide (Fe 3+ ), and precipitate, thereby reducing the ferrous ions (Fe 2+ ) to meet drainage standards. The present invention is efficient, environmentally friendly, and easy to operate, and is particularly suitable for situations where large-scale groundwater extraction and discharge are required.

[0005] The present invention provides a device for increasing the gas content of a liquid, comprising a filter bed top plate, a filter bed middle 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 plate, and a filter bed bottom plate arranged in sequence; the filter bed middle plate forms an acute angle with a horizontal plane at its starting point as a vertex; each filter bed middle plate has a water leakage hole at its lower portion to allow liquid to pass through; when multiple filter bed middle plates are provided, adjacent filter bed middle plates are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle 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-panel are internally connected to transport gas.

[0008] Preferably, the ventilation main panels are arranged to be inclined, and the inclination direction is such that 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 leaks directly from the water leakage hole, 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 in 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 includes the above-mentioned device for increasing the gas content in liquid for oxygenating the water. The structure of the device includes:

[0013] pre-treatment unit, including filter;

[0014] an oxygen enrichment unit comprising a ventilation main and the aforementioned 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 non-woven geotextile is arranged on the surface of the filter patch.

[0017] On the other hand, the present invention provides a filtration method for efficiently reducing iron ions in groundwater, which is composed of a pumping unit, a pretreatment unit, an aeration unit, a sedimentation tank unit, and a drainage unit. 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 aeration unit with a multi-layer porous filter bed, to increase the oxygen content in the water. The water after aeration flows into the sedimentation tank unit, and the ferrous ions (Fe 2+ ) oxidation reaction to generate water-insoluble trivalent iron oxide (Fe 3+ ), and precipitate, thereby reducing the ferrous ions (Fe 2+ Finally, the water passes through the drainage unit and is discharged after being monitored to meet the discharge standards. 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 fully contact the extracted groundwater with air, thereby achieving efficient oxidation of the iron ions and precipitation in a sedimentation tank. The specific implementation includes the following steps:

[0019] Step 1: Groundwater is pumped out by a pumping unit and flows into a pretreatment unit through an inlet pipe. The pumping unit includes a pump and an inlet pipe.

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

[0021] In step 3, after entering the aeration unit, the water flows through the multi-layer porous filter bed, where it is repeatedly aerated to increase the oxygen content in the water. The aerated water then flows into the sedimentation tank unit. The aeration process involves using an air compressor to pump air into the multi-layer porous filter bed, resulting in repeated contact between the water and air. The air compressor is connected to the filter bed via a connecting pipe.

[0022] Step 4: The oxygenated water flows into the sedimentation tank through the pipeline, and the ferrous ions (Fe 2+ ) is more fully oxidized with oxygen in water and produces trivalent iron oxide (Fe 3+ ) deposition.

[0023] In step 5, the sedimented water passes through the drainage unit and is monitored to ensure it meets discharge standards before being discharged. If it does not meet standards, the groundwater treatment is brought up to standard by adjusting the aeration rate to increase oxygen or by increasing the flow path through the sedimentation tank unit to increase the sedimentation time.

[0024] Preferably, in the above-mentioned method, the device for increasing the gas content of a liquid as described herein comprises a multi-layer porous filter bed having a three-dimensional structure, comprising a top plate, a middle baffle, a bottom plate, a primary ventilation panel, and a secondary ventilation panel, each of which has drainage holes. The top plate, middle baffle, and bottom plate are connected by the primary ventilation panel. The number of the middle baffles 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 all 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, and the ventilation is relatively sufficient.

[0026] Preferably, the top plate and the middle partition 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, so that when water falls from the top plate and the middle partition, 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 perpendicular to the ventilation main panel.

[0028] Preferably, the ventilation main panel and ventilation sub-panel are composed of a hollow plywood, a ventilation main pipe, and capillary tubes. The plywood surface is densely perforated with ventilation panel holes. The capillary tubes are connected to the ventilation main pipe, which is in turn connected to the ventilation connecting pipe. The capillary tubes are densely perforated with capillary holes. Air passes through the connecting pipe, ventilation main pipe, capillary tubes, and capillary holes, and is blown out through the ventilation panel holes, ultimately re-mixing with water that lands on the ventilation main panel and ventilation sub-panel.

[0029] Preferably, the interior of the sedimentation tank unit of the device of the present invention is made into a tortuous form to increase the path of groundwater flow, allowing more time for groundwater iron oxides (Fe 3+ )settlement.

[0030] Preferably, a porous filter patch is fixed on the wall of the sedimentation tank. The porous filter patch can further absorb the groundwater iron oxide (Fe 3+ ). When there is too much sediment, the filter patch can be removed and replaced with a new one.

[0031] Preferably, the filter patch is formed by bonding a porous non-woven geotextile at the bottom and a plastic grid at the top. The non-woven geotextile provides a porous structure to filter sediment, while the plastic grid can store sediment and prevent it 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 long-term stable operation of the device.

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

[0034] 1. This invention features a three-dimensional, multi-layered porous filter bed that allows for ample contact between water and air, increasing oxygen levels in the water. This simple setup offers low-cost, high-efficiency groundwater treatment.

[0035] 2. This invention incorporates a tortuous flow path and filter patches within the sedimentation tank unit to enhance the precipitation of iron oxide products. Furthermore, the filter patches are made of reusable and corrosion-resistant fabric. Once the iron oxide products have settled to a certain level, the geosynthetic fabric is removed and, after airing, the sediment can be separated from the geosynthetic fabric, achieving its reuse goal.

[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 the 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 This is a side view of the ventilation sub-panel.

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

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

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

[0047] Figure 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-pump; 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; 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 tube; 429-capillary tube hole; 430-plywood; 431-strip leakage hole. Specific embodiments

[0049] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described 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, a device for increasing the gas content of a liquid comprises a filter bed top plate 421, a filter bed middle 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 plate 422, and a filter bed bottom plate 423 arranged in sequence; the filter bed middle plate 422 forms an acute angle with the horizontal plane at its starting point as the vertex; each filter bed middle plate 422 has a water leakage hole at its lower portion to allow liquid to pass through. When there are multiple filter bed middle plates 422, adjacent filter bed middle plates 422 are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle 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, which is the filter bed top plate 421 or the filter bed bottom plate 423 or another filter bed middle partition 422; one end of multiple 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 tilt 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 the 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 are provided at different heights on the filter bed partition 422 to allow liquid to pass through. To match this, the ventilation sub-panel 425 forms an acute angle with the ventilation main panel 424 above it and is connected thereto, i.e., it extends obliquely upwards. When the liquid does not reach the lowest point of the filter bed partition 422 and directly leaks out of 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] The pre-processing unit 30 includes a filter 31;

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

[0062] like Figure 10As shown, the sedimentation tank unit 50 includes sedimentation tank walls 51 and filter patches 52 arranged at intervals. 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. 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 in the forward direction to rub against the two sides of each filter patch 52, rather than just directly passing through the filter patch 52. Figure 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 content exceeds the standard and cannot be discharged directly 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 both 3m×3m, and the depth is 2m; the plane dimensions 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 achieve the reduction of iron ion content, the following steps are mainly followed:

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

[0066] Step 2: After entering the pre-treatment unit, the water is initially filtered by three layers of filters to reduce large particles and suspended solids. The pre-treated water then flows into the aeration unit.

[0067] In step 3, after entering the aeration unit, the water flows through a multi-layer porous filter bed, where it is repeatedly aerated to increase the oxygen content in the water. The aerated water then flows into the sedimentation tank unit. The aeration process involves using an air compressor to pump air into the multi-layer porous filter bed, allowing repeated contact between the water and air. The air compressor is connected to the filter bed via a connecting pipe. The air compressor's boost pressure is 1.5 bar.

[0068] Step 4: The oxygenated water flows into the sedimentation tank through the pipeline, and the ferrous ions Fe 2+ More fully oxidized with oxygen in water and produced trivalent iron oxide Fe 3+ sedimentation.

[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 drawings provide visual support for the specific embodiments of the present invention and help to understand 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 separator (422), and a filter bed bottom plate (423) arranged in sequence; the filter bed middle separator (422) forms an acute angle with a horizontal plane at its starting point as a vertex; each filter bed middle separator (422) is provided with a water leakage hole at its lower portion for allowing liquid to pass through; when there are multiple filter bed middle separators (422), adjacent filter bed middle separators (422) are inclined in different directions above or below the horizontal plane to allow liquid to pass through different filter bed middle separators (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 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 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 tilted, and the tilt direction is such that the lowest point of each ventilation main panel (424) is closer to the water coming in the opposite direction than the highest point thereof.

3. The device according to claim 1, characterized in that The filter bed partition (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 are provided at different heights on the filter bed partition (422) to allow liquid to pass through. To match this, the ventilation sub-panel (425) and the ventilation main panel (424) connected thereto form an acute angle, that is, extend obliquely upwards. When the liquid does not reach the lowest point of the filter bed partition (422) and directly leaks from the water leakage holes, the liquid will inevitably contact the ventilation sub-panel (425) below.

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-processing unit (30) including 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) includes 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: Pump water out of the ground; Step 2: passing the water to be treated into the pretreatment unit and filtering it through a filter; Step 3: After the water flows into the aeration unit, it flows through the multi-layer porous filter bed and is repeatedly aerated to increase the oxygen content in the water. The aerated water flows into the sedimentation tank unit. The aeration is performed by using an air compressor to pump air into the multi-layer porous filter bed, so that the water and air are repeatedly in contact. Step 4: The oxygen-injected water flows into the sedimentation tank through the pipeline, and the ferrous ions in the water are more fully oxidized with the oxygen in the water, and trivalent iron oxide precipitation is produced.

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