A geotube bag that can stabilize heavy metals and efficiently dehydrate

Abstract

The present invention discloses a geotube bag capable of stabilizing heavy metals and achieving efficient dehydration, comprising: an inner fabric layer, the inner side of which is provided with a heavy metal adsorption layer containing a heavy metal adsorbent; an intermediate fabric layer, the intermediate layer located outside the inner fabric; the intermediate fabric having a greater hydrophilicity than the inner fabric; and an average pore size larger than that of the intermediate fabric; and an outer fabric layer located outside the intermediate fabric; the outer fabric having a greater hydrophilicity than the intermediate fabric and an average pore size larger than that of the outer fabric. The geotube bag's unique structure improves dehydration efficiency, avoids secondary contamination of sediment by the use of flocculants, and improves treatment efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal sludge treatment, and in particular to a geotube bag capable of stabilizing heavy metals and efficiently dehydrating. Background Art

[0002] With the advancement of industrialization, large amounts of heavy metals have been deposited in the sediments of rivers and lakes. Data show that the contamination rate of sediment in my country's water bodies has reached 80.1%. Heavy metal levels in the sediments of major rivers and lakes exceed local soil background values, posing a serious threat to aquatic ecosystems and human health. The conventional treatment method for this type of sediment is environmentally friendly dredging. However, dredged sediment has a high water content and is difficult to transport. Therefore, efficient dewatering to reduce the amount of sediment to be handled is a key step in the sediment management process. Common sediment dewatering methods include natural drying in a dump, mechanical dewatering, and geotube dewatering. Geotube dewatering involves transferring dredged sediment into geotextile bags. The filling pressure within the bag forces free water to drain through the pores of the geotextile, while solids are retained within the bag. Compared with traditional high-water content sludge dewatering technologies, geotube dewatering offers advantages such as ease of construction, convenient placement, reduced footprint, high efficiency, low cost, labor savings, and minimal environmental impact. It is widely used for dewatering dredged sediment. However, the liquid seepage time of the geotube bags currently used for dehydration treatment is relatively long, and it takes at least ten days of dehydration and solidification time to reduce the sludge moisture content to below 60%.

[0003] For example, after the pre-treated bottom mud is filled into the geotextile tube bag body, a soluble flocculant, adsorbent and stabilizer are added to the geotextile tube bag to quickly discharge the water in the mud to form a block of silt, which is subsequently continuously dehydrated by gravity factors, rheological factors, etc. This method involves two agents, the operation is relatively complicated, and the addition of flocculants poses a risk of secondary pollution to the bottom mud. Alternatively, a certain amount of heavy metal conditioning agent solution is first added to the contaminated bottom mud, and then the bottom mud treated with the heavy metal stabilizer is transported to the geotextile tube bag for dehydration and volume reduction. This method mainly relies on the effect of deadweight for dehydration, does not consider the enhanced dehydration effect, and has a long dehydration time and low efficiency. Alternatively, the heavy metal sludge is subjected to ultrasonic treatment and flocculation reaction before entering the geotextile tube bag for mud-water separation. The process is complicated and the operating cost is high, which can easily cause secondary pollution to the bottom mud.

[0004] In summary, current heavy metal contaminated sludge treatment technologies separate the heavy metal treatment process from the dehydration process, requiring the use of flocculants to accelerate dehydration. This leads to complex processes, low dehydration efficiency, and the potential for secondary contamination of the sludge. Therefore, it is necessary to develop a geotube bag that combines heavy metal stabilization with dehydration volume reduction, increasing sludge dehydration efficiency and ensuring that the heavy metal leaching content of the dehydrated sludge meets the requirements for subsequent sludge disposal. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a geotube bag that can stabilize heavy metals and efficiently dehydrate, and a preparation method thereof.

[0006] A geotube bag capable of stabilizing heavy metals and efficiently dehydrating, comprising:

[0007] An inner fabric, wherein a heavy metal adsorption layer is provided on the inner side of the inner fabric, and the heavy metal adsorption layer contains a heavy metal adsorbent;

[0008] The middle layer fabric is located outside the inner layer fabric; the hydrophilicity of the middle layer fabric is greater than that of the inner layer fabric; the average pore size of the inner layer fabric is greater than the average pore size of the middle layer fabric

[0009] The outer fabric is located outside the middle fabric; the hydrophilicity of the outer fabric is greater than that of the middle fabric, and the average pore size of the middle fabric is greater than that of the outer fabric.

[0010] Optionally, the inner fabric and the outer fabric are both non-woven fabrics with a surface density of 80 to 150 g / m 2 .

[0011] Optionally, the middle layer is made of woven fabric with a surface density of 100 to 300 g / m 2 , thickness is 0.4~0.7mm.

[0012] Optionally, the average pore size of the inner fabric is 45-55 μm, the average pore size of the middle fabric is 25-35 μm, and the average pore size of the outer fabric is 20-30 μm.

[0013] Optionally, the inner fabric is made of hydrophobic fiber with corrosion resistance and acid and alkali resistance, the middle fabric is made of corrosion resistance, acid and alkali resistance and high strength fiber, and the outer fabric is made of relatively fine hydrophilic fiber.

[0014] Optionally, the inner fabric is made of ES hydrophobic fiber or polytetrafluoroethylene fiber;

[0015] The middle layer fabric is made of polypropylene fiber or polyethylene fiber;

[0016] The outer fabric is made of viscose fiber, cotton fiber or linen fiber.

[0017] Optionally, the heavy metal adsorbent is biochar.

[0018] Optionally, the particle size of the biochar is larger than the pore size of the inner fabric.

[0019] Optionally, the inner fabric, the middle fabric and the outer fabric are combined together by needle punching.

[0020] Optionally, the heavy metal adsorption layer is formed by bonding a heavy metal adsorbent to the surface of the inner fabric by coating or thermal bonding.

[0021] Optionally, the weight of the heavy metal adsorbent contained in the geotube bag is 15% to 50% of the dry weight of the sludge treated by the geotube bag.

[0022] The present invention also proposes the use of the above-mentioned geotube bag capable of stabilizing heavy metals and efficiently dehydrating in treating sediment.

[0023] As described above, the present invention relates to a geotube bag for stabilizing heavy metals and efficiently dehydrating sediment, which has the following beneficial effects:

[0024] The present invention provides an inner layer of fabric, an intermediate layer of fabric, and an outer layer of fabric. By setting the pore size gradient of the three layers of fabric, capillary pressure is generated to provide an auxiliary driving force for fluid transmission. At the same time, the hydrophilicity difference between the three layers of fabric also provides an attraction for the outward transport of water. Under the action of acupuncture, the fibers form fiber clusters connecting the inner and outer layers and through-holes, providing a structural basis for the rapid transmission of liquid along the thickness direction. Relying on the special structure of the geotube bag to improve the dehydration efficiency can avoid the use of flocculants to cause secondary pollution to the bottom mud. In addition, the heavy metal stabilizer of the present invention is loaded in the geotube bag, combining heavy metal stabilization and dehydration volume reduction, while achieving stabilization and reduction of heavy metal-contaminated bottom mud, so that the dehydrated bottom mud can meet the requirements of subsequent sludge disposal. Improved processing efficiency.

[0025] The present invention is a non-woven fabric and woven composite geotextile tube bag, which has the advantages of high strength and small tensile strain of woven geotextile, and excellent filtration performance of non-woven geotextile. Therefore, compared with traditional geotextile tube bags, the composite geotextile tube bag can effectively reduce the amount of bottom sediment loss and overcome the disadvantage of poor sludge retention effect of traditional geotextile tube bags. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a field emission scanning electron microscope photograph of the cross-section of the geotube bag capable of stabilizing heavy metals and efficiently dehydrating provided in Example 1. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] The present invention provides a geotube bag capable of stabilizing heavy metals and efficiently dehydrating. The geotube bag comprises an inner fabric prepared by a non-woven process, an outer fabric, and an intermediate fabric prepared by a weaving process. The non-woven inner fabric is prepared by hydrophobic fibers, and the non-woven outer fabric is prepared by hydrophilic fibers. The non-woven inner layer structure is fluffy, and the non-woven outer layer structure is compact. The three-layer fabric has a double gradient distribution from the inside to the outside, with the pore size decreasing and the hydrophilicity increasing. The non-woven inner layer is loaded with a heavy metal stabilizer. Water contained in heavy metal-contaminated sediment quickly seeps out through the geotube bag, and the heavy metals in the water are adsorbed by the heavy metal stabilizer loaded by the non-woven inner layer.

[0035] Preferably, the hydrophobic fiber is ES hydrophobic fiber, and the hydrophilic fiber is viscose fiber.

[0036] Preferably, the average diameter of the ES hydrophobic fiber is 15 to 25 μm, and the average diameter of the viscose fiber is 9 to 12 μm.

[0037] Preferably, the woven middle layer is made of polypropylene woven fabric, and the polypropylene woven fabric is a plain fabric with a surface density of 100 to 300 g / m 2 , thickness is 0.4~0.7mm.

[0038] Preferably, the heavy metal stabilizer is biochar, and the biochar is sieved to ensure that its particle size is larger than the pore size of the fabric to reduce particle escape.

[0039] Preferably, the density of the nonwoven inner layer and the nonwoven outer layer is 80 to 150 g / m 2 .

[0040] Preferably, the biochar content loaded on the non-woven inner layer is 5% to 15% of the amount of the treated sludge.

[0041] The above-mentioned geotube bag method comprises the following steps:

[0042] Step 1: Prepare the non-woven inner layer. Weigh the required mass of hydrophobic fibers and make them into a non-woven web with a surface density of not less than 50g / m2 through a non-woven carding and laying process. 2 The fiber web is needle-punched to form a nonwoven fabric. The biochar is sieved and loaded onto the prepared nonwoven fabric through a coating or thermal bonding process.

[0043] Step 2: Prepare the non-woven outer layer. Weigh the required mass of hydrophilic fibers and make them into a non-woven web with a surface density of not less than 50g / m2 through a non-woven carding and laying process. 2 The fiber web is made into a nonwoven fabric by a needle-punching or hydroentanglement process.

[0044] Step 3: Three-layer fabric composite: The non-woven inner layer, woven middle layer and non-woven outer layer prepared in the above steps are stacked from top to bottom, and then needle-punched to form a flat composite geotextile.

[0045] Step 4: The prepared planar composite geotextile is needle-punched and sewn to obtain a geotube bag.

[0046] Example 1

[0047] like Figure 1 The geotube bag, which stabilizes heavy metals and efficiently dehydrates, comprises an inner fabric layer, an outer fabric layer, and a woven intermediate fabric layer. The inner nonwoven fabric is made of hydrophobic fibers, while the outer nonwoven fabric is made of hydrophilic fibers. The hydrophobic fibers are larger in diameter than the hydrophilic fibers. The inner nonwoven fabric has a fluffy structure, while the outer nonwoven fabric has a compact structure. The three fabric layers exhibit a dual gradient distribution from the inside out, with decreasing pore size and increasing hydrophilicity. The inner nonwoven fabric layer is loaded with a heavy metal stabilizer. Water from heavy metal-contaminated sediment rapidly seeps through the geotube bag, and the heavy metals in the water are adsorbed by the heavy metal stabilizer loaded into the inner nonwoven fabric layer.

[0048] The hydrophobic fiber used in the nonwoven inner layer fabric in this embodiment is ES hydrophobic fiber, a hot-melt fiber with a sheath-core structure, with a polyethylene sheath and a polypropylene core. The middle layer fabric is a polypropylene woven fabric, and the hydrophilic fiber used in the nonwoven outer layer fabric is viscose fiber.

[0049] The average diameter of the ES hydrophobic fiber is 15 μm, and the average diameter of the viscose fiber is 9 μm, ensuring a pore size gradient between the three layers of fabric. The average pore size of the non-woven inner layer is 45 μm, the average pore size of the woven middle layer is 25 μm, and the average pore size of the non-woven outer layer is 20 μm, forming a gradient distribution of gradually decreasing pore sizes. The woven middle layer is made of polypropylene woven fabric with a thickness of 0.5 mm and a surface density of 160 g / m 2 The heavy metal stabilizer is corn straw biochar. The corn straw biochar is passed through a 100-mesh sieve to ensure that its particle size is larger than the pore size of the fabric to reduce particle escape.

[0050] The above-mentioned geotube bag method specifically includes the following steps:

[0051] Step 1: Prepare the nonwoven inner layer. Weigh the required mass of ES hydrophobic fiber and make it into a nonwoven web with a surface density of 120g / m2 through a nonwoven carding and laying process. 2The fiber web was needle-punched to form a nonwoven fabric. The corn straw biochar was passed through a 100-mesh sieve. A mixture of 15% corn straw biochar (purchased from Lize Environmental Protection Technology Co., Ltd.) and 50% corn straw dry weight (by weight) was mixed with hot melt adhesive at a 2:1 weight ratio. The mixture was sprayed onto the nonwoven fabric and hot-pressed at 110°C. The hot melt adhesive bonded the corn straw biochar to the nonwoven fabric.

[0052] Step 2: Prepare the nonwoven outer layer. Weigh the required mass of viscose fiber and make it into a nonwoven web with a surface density of 120g / m2 through a nonwoven carding and laying process. 2 The fiber web is made into a nonwoven fabric through a hydroentanglement process.

[0053] Step 4: Three-layer fabric composite: The prepared non-woven inner layer, woven middle layer and non-woven outer layer are stacked in sequence from top to bottom, and then needle-punched to prepare a flat composite geotextile.

[0054] Step 5: The prepared planar composite geotextile is needle-punched and sewn to obtain a geotube bag.

[0055] Example 2

[0056] The second embodiment is basically the same as the first embodiment, but differs from the first embodiment in that:

[0057] The average diameter of the ES hydrophobic fibers is 20 μm, and the average diameter of the viscose fibers is 10 μm, ensuring a pore size gradient across the three fabric layers. The average pore size of the nonwoven inner layer is 50 μm, the average pore size of the woven middle layer is 30 μm, and the average pore size of the nonwoven outer layer is 25 μm, creating a gradient distribution of gradually decreasing pore sizes. The heavy metal stabilizer is rice straw biochar. The rice straw biochar is sieved through a 100-mesh screen to ensure that its particle size is larger than the fabric pore size, reducing particle escape.

[0058] The above-mentioned geotube bag method specifically includes the following steps:

[0059] Step 1: Prepare the nonwoven inner layer. Weigh the required mass of ES hydrophobic fiber and make it into a nonwoven web with a surface density of 100g / m2 through a nonwoven carding and laying process. 2 The fiber mesh was needle-punched to form a nonwoven inner layer. The rice straw biochar was passed through a 100-mesh sieve. Rice straw biochar (purchased from Li Ze Environmental Protection Technology Co., Ltd.) containing 33% of the desired sediment dry weight was mixed with hot melt adhesive at a weight ratio of 2:1. The mixture was sprayed onto the nonwoven inner layer and hot-pressed at 120°C. The hot melt adhesive bonded the rice straw biochar to the prepared nonwoven fabric.

[0060] Step 2: Prepare the nonwoven outer layer. Weigh the required mass of viscose fiber and make it into a nonwoven web with a surface density of 100g / m2 through a nonwoven carding and laying process. 2 The fiber web is needle-punched to form a non-woven outer layer.

[0061] Step 4: Three-layer fabric composite: The prepared non-woven inner layer, woven middle layer and non-woven outer layer are stacked in sequence from top to bottom, and then needle-punched to prepare a flat composite geotextile.

[0062] Step 5: The prepared planar composite geotextile is needle-punched and sewn to obtain a geotube bag.

[0063] Example 3

[0064] The third embodiment is basically the same as the first embodiment. The difference between the third embodiment and the first embodiment is that:

[0065] The average diameter of the ES hydrophobic fiber is 25 μm, and the average diameter of the viscose fiber is 12 μm, ensuring a pore size gradient across the three fabric layers. The average pore size of the nonwoven inner layer is 55 μm, the average pore size of the woven middle layer is 35 μm, and the average pore size of the nonwoven outer layer is 30 μm, creating a gradient distribution of gradually decreasing pore sizes. The heavy metal stabilizer is corn straw biochar. The corn straw biochar is sieved through a 100-mesh screen to ensure its particle size is larger than the fabric pores, reducing particle escape.

[0066] The above-mentioned geotube bag method specifically includes the following steps:

[0067] Step 1: Prepare the nonwoven inner layer. Weigh the required mass of ES hydrophobic fiber and make it into a nonwoven web with a surface density of 80g / m2 through a nonwoven carding and laying process. 2 The fiber mesh was needle-punched to form a nonwoven inner layer. The rice straw biochar was passed through a 100-mesh sieve. A mixture of 50% rice straw biochar (purchased from Li Ze Environmental Protection Technology Co., Ltd.) and hot melt adhesive (3:1 by weight) was sprayed onto the nonwoven inner layer and hot-pressed at 125°C. The hot melt adhesive bonded the rice straw biochar to the nonwoven fabric.

[0068] Step 2: Prepare the nonwoven outer layer. Weigh the required mass of hydrophilic fibers and make a nonwoven web with a surface density of 80g / m2 through a nonwoven carding and laying process. 2 The fiber web is needle-punched to form a non-woven outer layer.

[0069] Step 4: Three-layer fabric composite: The prepared non-woven inner layer, woven middle layer and non-woven outer layer are stacked in sequence from top to bottom, and then needle-punched to prepare a flat composite geotextile.

[0070] Step 5: The prepared planar composite geotextile is needle-punched and sewn to obtain a geotube bag.

[0071] Comparative Example 1

[0072] Using Xianke plain woven geotube bags, the contaminated sludge is dredged and 35% of the dry weight of the sludge to be treated is added to the sludge pipeline for treatment. The sludge is then transported and filled into the geotube bag body for dehydration.

[0073] Comparative Example 2

[0074] Compared with Example 1, the only difference is that the inner layer, the middle layer and the outer layer are all made of polypropylene.

[0075] Comparative Example 3

[0076] Compared with Example 1, the average pore diameters of the inner layer, the middle layer, and the outer layer are all 30 μm.

[0077] Test example

[0078] The above comparative example and test example were used to treat the same amount of sediment. The sediment had a moisture content of 70% and contained heavy metals of 172 mg / kg of cadmium (Cd) and 2500 mg / kg of lead (Pb). The results are as follows:

[0079]

[0080]

[0081] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A geotube bag that can stabilize heavy metals and efficiently dehydrate, characterized in that: include: An inner fabric, wherein a heavy metal adsorption layer is provided on the inner side of the inner fabric, and the heavy metal adsorption layer contains a heavy metal adsorbent; an intermediate fabric layer, the intermediate fabric layer being located on the outside of the inner fabric layer; The hydrophilicity of the middle layer fabric is greater than that of the inner layer fabric; the average pore size of the inner layer fabric is greater than the average pore size of the middle layer fabric; an outer fabric, the outer fabric being located outside the middle fabric; the outer fabric being more hydrophilic than the middle fabric, and the middle fabric having an average pore size greater than the outer fabric; The heavy metal adsorbent is biochar; the particle size of the biochar is larger than the pore size of the inner fabric; The heavy metal adsorption layer is formed by bonding a heavy metal adsorbent to the surface of the inner fabric by coating or thermal bonding; The average pore size of the inner fabric is 45-55 μm, the average pore size of the middle fabric is 25-35 μm, and the average pore size of the outer fabric is 20-30 μm; The inner fabric is made of at least one of ES hydrophobic fiber and polytetrafluoroethylene fiber; The middle layer fabric is made of at least one of polypropylene fiber and polyethylene fiber; The outer fabric is made of at least one of viscose fiber, cotton fiber and linen fiber; The inner fabric, the middle fabric and the outer fabric are combined together by needle punching.

2. The geotube bag capable of stabilizing heavy metals and efficiently dehydrating according to claim 1, characterized in that: The inner fabric and the outer fabric are both non-woven fabrics, and the surface density of the inner fabric and the outer fabric is 80-150 g / m 2 .

3. The geotube bag capable of stabilizing heavy metals and efficiently dehydrating according to claim 1, characterized in that: The middle layer fabric is made of woven fabric, and the surface density of the middle layer fabric is 100-300g / m 2 , thickness is 0.4~0.7mm.

4. The geotube bag capable of stabilizing heavy metals and efficiently dehydrating according to claim 1, characterized in that: The weight of the heavy metal adsorbent contained in the geotube bag is 15% to 50% of the dry weight of the bottom mud treated by the geotube bag.

5. Use of the geotube bag capable of stabilizing heavy metals and efficiently dehydrating according to any one of claims 1 to 4 in treating sediment.

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