Method for forming a deposit layer of adsorbed powder in a filtration system and filtration membrane.

Abstract

This improves the density and homogeneity of the particle packing structure of the deposited layer on the filtration membrane. [Solution] The above problem is solved by a filtration system 1 comprising a slurry supply unit that supplies a slurry S2 for forming a deposit layer in which adsorbent powder 2 is dispersed in a dispersion liquid D, and a filtration device 1 that supplies the slurry S2 for forming a deposit layer from the slurry supply unit to the primary side of a filtration membrane 22m to perform total filtration, thereby forming a deposit layer 2K of adsorbent powder 2 on the primary side surface of the filtration membrane 22m, and then supplies the liquid to be treated A to the primary side of the filtration membrane to perform total filtration, wherein the slurry supply unit comprises a slurry production unit 110 that continuously produces a slurry S2 for forming a deposit layer using the dispersion liquid D and the adsorbent powder 2, and a slurry delivery unit 120 that supplies the slurry S2 for forming a deposit layer produced continuously in the slurry production unit 110 to the primary side of the filtration membrane 22m via a delivery line mixer 8 without stagnation.

Description

【Technical Field】 【0001】 The present invention relates to a filtration system and a filtration method for performing total filtration of a liquid to be treated by a filtration layer having a filtration membrane and a deposition layer of adsorbent powder attached to the surface on the primary side of the filtration membrane. 【Background Art】 【0002】 As one of the filtration technologies for a liquid to be treated, for example, wastewater generated at factories, construction sites, etc., there is known a filtration technology that performs total filtration by a filtration layer having a filtration membrane and a deposition layer of adsorbent powder attached to the surface on the primary side of the filtration membrane (see, for example, Patent Documents 1 and 2). 【0003】 In this prior art, prior to the filtration treatment, a slurry in which adsorbent powder such as activated carbon is dispersed in water or the like is filtered through a filtration membrane, and the adsorbent powder is deposited on the surface on the primary side of the filtration membrane to form a deposition layer. During filtration, as the liquid to be treated passes through the deposition layer of the adsorbent powder, the separation target substance in the liquid to be treated is adsorbed by the adsorbent powder, and the permeate in which the separation target substance is separated and removed by passing through the deposition layer and the filtration membrane is discharged as filtrate (treated liquid). 【0004】 In such a filtration mechanism, the density and homogeneity of the particle packing structure of the deposition layer are important. For example, if there are inhomogeneous defects such as cracks or relatively large pores in the deposition layer, or if there are locally thin portions, the liquid to be treated may short-circuit through these inhomogeneous defects, resulting in an extremely short breakthrough time and the inability to exhibit the required performance. 【0005】 Further, the deposition layer is one in which the adsorbent powder is maintained in an aggregated state (layer shape) and an attached state to the filtration membrane by intermolecular forces (van der Waals force, electrostatic force, hydrogen bond), and no adhesive, binder, welding, etc. is performed, and cracks, peeling, collapse, etc. may occur due to an external force. Therefore, if the particle packing structure of the deposition layer is not dense, the durability of the deposition layer will be low, and cracks may occur in the deposition layer due to vibration, pulsation, etc., or it may gradually collapse from the surface, resulting in a short breakthrough time. 【0006】 However, no methods have been established to improve the density and homogeneity of the particle-packing structure of sedimentary layers. [Prior art documents] [Patent Documents] 【0007】 [Patent Document 1] Japanese Patent Publication No. 2005-131538 [Patent Document 2] Japanese Patent Publication No. 2022-69280 [Patent Document 3] Japanese Patent Publication No. 2023-145713 [Overview of the Initiative] [Problems that the invention aims to solve] 【0008】 Therefore, the main objective of the present invention is to improve the density and homogeneity of the particle packing structure of the deposited layer deposited on the primary side surface of the filtration membrane. [Means for solving the problem] 【0009】 The filtration system and the method for forming the adsorbed powder deposit layer in the filtration membrane that solve the above problems are as follows. <First aspect> It includes a slurry supply unit that supplies a slurry for forming a deposition layer in which adsorbent powder is dispersed in a dispersion liquid, After supplying the slurry for forming the deposition layer from the slurry supply unit to the primary side of the filtration membrane and performing total filtration, a deposition layer of the adsorbed powder is formed on the primary side surface of the filtration membrane, In a filtration system in which the liquid to be treated is supplied to the primary side of the filtration membrane to perform total filtration, The slurry supply unit comprises a slurry production unit that continuously produces the slurry for forming the deposition layer using the dispersion and the adsorbent powder, and a slurry delivery unit that supplies the slurry for forming the deposition layer, which is continuously produced in the slurry production unit, to the primary side of the filtration membrane via a delivery line mixer without stagnation. A filtration system characterized by the following features. 【0010】 (Effects and Benefits) In this filtration system, the continuously produced slurry for forming the deposit layer is supplied to the primary side of the filtration membrane without stagnation, making it difficult for adsorbed powder in the slurry to aggregate. Furthermore, since the slurry for forming the deposit layer is passed through a delivery line mixer before being supplied to the primary side of the filtration membrane, the slurry is spatially constrained within the delivery line mixer and forcibly agitated with shear action. Even if there are aggregates or clumps of adsorbed powder, they are effectively broken down into single particles (single particle formation effect). In other words, in this filtration system, the entire slurry for forming the deposit layer, which contains more dispersed single particles than in conventional systems, is filtered by the filtration membrane without stagnation, thus improving the density and homogeneity of the particle-packed structure of the deposit layer compared to conventional systems. Furthermore, the system described in Patent Document 3, while using a line mixer to mix the slurry, differs fundamentally from this filtration system in that the mixed slurry is retained in an adsorption reactor and no deposit layer is formed because cross-flow filtration is performed. 【0011】 <Second aspect> The slurry preparation unit is, A powder supply device for quantitatively supplying the adsorbed powder, A dispersion supply source that supplies the aforementioned dispersion, An additive unit adds the adsorbent powder supplied in a fixed quantity from the powder supply device to the dispersion supplied in a fixed quantity from the dispersion supply source, An intermediate line mixer mixes the dispersion liquid to which the adsorbent powder has been added in the additive section to produce a primary slurry, The system includes a dilution unit that prepares the slurry for forming the deposition layer by adding the dispersion to the primary slurry discharged from the intermediate line mixer and diluting it, A filtration system according to a first embodiment. 【0012】 (Effects and Benefits) When preparing the slurry in two steps like this filtration system, namely the step of preparing the primary slurry from the dispersion liquid and the adsorbent powder, and the step of preparing the slurry for forming the deposition layer by diluting this primary slurry, and performing mixing by an intermediate line mixer between these steps, overall, mixing by at least two line mixers is performed. Therefore, the dispersibility of the adsorbent powder in the slurry for forming the deposition layer is significantly improved. In particular, it is preferable to perform dilution with the dispersion liquid upstream of the delivery line mixer because the single-particle forming action in the delivery line mixer is more likely to be exerted. 【0013】 <The third aspect> Equipped with a defoaming device for the primary slurry, interposed in the flow path between the addition part and the dilution part The filtration system of the second aspect. 【0014】 (Function and effect) When the adsorbent powder is supplied by a metering device, air is mixed into the primary slurry. If such air is mixed into the slurry for forming the deposition layer, there is a risk that defects such as bubbles, lumps, and cracks will be formed on the surface or in the deposition layer. In contrast, as in this aspect, if a defoaming device is used to remove air from the primary slurry prior to dilution of the primary slurry (production of the slurry for forming the deposition layer), such defects are less likely to occur. 【0015】 <The fourth aspect> The slurry preparation part has a supply pump in the flow path on the downstream side of the dilution part, The supply pump is configured to draw the dispersion liquid from the dispersion liquid supply source into the dilution part, and draw the primary slurry defoamed by the defoaming device into the dilution part for dilution, and then pressure-feed it to the delivery line mixer of the slurry delivery part. The filtration system of the third aspect. 【0016】 (Function and effect) When using the aforementioned defoaming device, if the supply pump is arranged as in this embodiment, the supply of additional dispersion liquid and primary slurry to the dilution section and the pumping of the slurry for forming a deposited layer after dilution to the delivery line mixer can be performed with a single pump. Also, the stirring action of the supply pump upstream of the delivery line mixer promotes the mixing of the additional dispersion liquid and the primary slurry, bringing the advantage of being able to do so. 【0017】 <The fifth embodiment> The slurry preparation section has an addition pump in the flow path between the addition section and the intermediate line mixer. The addition pump is configured to draw the dispersion liquid from the dispersion liquid supply source into the addition section and draw the dispersion liquid with the adsorbed powder added from the addition section and pump it to the intermediate line mixer. The filtration system according to any one of the second to fourth embodiments. 【0018】 (Function and effect) When the addition pump is arranged as in this embodiment, the supply of the dispersion liquid to the addition section and the pumping of the dispersion liquid with the adsorbed powder added to the intermediate line mixer can be performed with a single pump. Also, the stirring action of the addition pump upstream of the intermediate line mixer promotes the mixing of the dispersion liquid and the adsorbed powder, bringing the advantage of being able to do so. 【0019】 <The sixth embodiment> In a method of forming a deposited layer of the adsorbed powder on the primary side surface of the filtration membrane by supplying a slurry for forming a deposited layer in which the adsorbed powder is dispersed in the dispersion liquid to the primary side of the filtration membrane and performing total amount filtration, The slurry for forming a deposited layer is continuously produced and supplied using the dispersion liquid and the adsorbed powder, and the continuously produced slurry for forming a deposited layer is supplied to the primary side of the filtration membrane through a delivery line mixer without being retained. A method for forming a deposited layer of an adsorbed powder on a filtration membrane, characterized by the above. 【0020】 (Function and effect) It produces the same effects as the first embodiment. [Effects of the Invention] 【0021】 According to the present invention, it becomes possible to improve the density and homogeneity of the particle packing structure of the deposited layer deposited on the primary side surface of the filtration membrane. [Brief explanation of the drawing] 【0022】 [Figure 1] This is a schematic diagram showing an example of a slurry supply unit. [Figure 2] This is a schematic diagram showing an example of a slurry supply unit. [Figure 3] This is a schematic diagram showing an example of a slurry supply unit. [Figure 4] This is a schematic diagram showing an example of a slurry supply unit. [Figure 5] This is a schematic diagram showing an example of a filtration system. [Figure 6] This is a cross-sectional view showing enlarged views of the main parts of the filtration membrane, deposit layer, and cake. [Modes for carrying out the invention] 【0023】 An example of the present invention will be described below. However, the following description and drawings are merely examples, and the content of the present invention should not be interpreted as being limited to the following description and drawings. 【0024】 Figure 5 shows an example of a filtration system 1. This filtration system 1 comprises a filtration unit 10 that filters the entire volume of the liquid to be treated A through a filtration membrane 22m, and a slurry supply unit 100 that supplies a slurry S2 for forming a deposit layer, in which adsorbed powder 2 is dispersed in a dispersion liquid D, to the filtration unit 10. 【0025】 (Treatment liquid A) Examples of treated liquids A include: tunnel premises wastewater, sprayed concrete plant wastewater, die slime recovery wastewater, batching plant wastewater, river construction dry pit wastewater, deep foundation construction wastewater, grout construction wastewater, shield construction wastewater, shield excess slurry, dredging and landfill wastewater, caisson construction wastewater, cast-in-place pile wastewater, floor surface cleaning wastewater, wellpoint construction wastewater, foundation construction yard wastewater, tire cleaning wastewater, core boring wastewater, diamond cutter wastewater, soil contamination excavation yard wastewater, VOC decomposition cleaning wastewater, incinerator dismantling and cleaning wastewater, radioactive decontamination construction wastewater, wire saw cutting construction wastewater, water jet cutting construction wastewater, paper mill process wastewater, pulp mill process wastewater, food factory cleaning wastewater, ready-mix concrete plant cleaning wastewater, concrete secondary product factory wastewater, and crushed stone work. Examples of wastewater include yard drainage, gas scrubber drainage, waste incinerator quenching tower drainage, converter gas scrubbing drainage, arc furnace gas scrubbing drainage, silver recovery process drainage, sand washing equipment drainage, water washing neutralization drainage, barrel polishing drainage, electropolishing drainage, glass polishing drainage, wet blasting drainage, spray painting booth drainage, cationic coating drainage, stainless steel pickling drainage, raw material yard drainage, raw material conveyor cleaning drainage, wet dust recovery drainage, factory yard drainage, continuous casting drainage, rolling cooling drainage, dehumidification drainage, immersion cutting yard drainage, slag yard drainage, ship bottom bilge drainage, shipbuilding dock drainage, shellfish removal drainage, cooling tower blowdown drainage, dyeing factory drainage, milk plant cleaning drainage, tunnel wall cleaning drainage, building exterior wall cleaning drainage, car wash drainage, golf course drainage, industrial disposal site leachate, etc. 【0026】 As shown in Figure 1, the slurry supply unit 100 includes a slurry preparation unit 110 and a slurry delivery unit 120. The slurry preparation unit 110 is not particularly limited as long as it continuously prepares a slurry S2 for forming a deposition layer using a dispersion liquid D and adsorbent powder 2. The slurry preparation unit 110 may, for example, include a powder supply device 3 for quantitatively supplying adsorbent powder 2, a dispersion liquid supply source 4 for supplying the dispersion liquid D, and an addition unit 5 for adding adsorbent powder 2 to the dispersion liquid D, as shown in Figure 3. Preferably, the slurry preparation unit 110 includes, for example, a powder supply device 3 for quantitatively supplying adsorbent powder 2, a dispersion liquid supply source 4 for supplying dispersion liquid D, an addition unit 5 for adding adsorbent powder 2 to dispersion liquid D, an intermediate line mixer 6 for mixing the dispersion liquid D to which the adsorbent powder 2 has been added in the addition unit 5 to produce a primary slurry S1, and a dilution unit 7 for producing a slurry S2 for deposit layer formation by adding dispersion liquid D to the primary slurry S1 discharged from the intermediate line mixer 6 and diluting it. 【0027】 (Adsorbent powder) The adsorbent powder 2 constituting the sedimentary layer 2K can be appropriately selected from one or more types depending on the target of adsorption. For example, if it is desired to remove PFOS and its salts, PFOA and its salts and PFOA-related substances, PFHxS and its salts and PFHxS-related substances, and PFHxA, activated carbon can be used as the adsorbent powder 2. Other adsorbent powders 2 that can be used include, for example, organic porous materials such as ion exchange resins, zeolites, metal-organic frameworks (MOFs), diatomaceous earth, acid clay, activated clay, inorganic porous materials such as carbon black, metal oxides and metal powders such as titanium dioxide, and substances such as Prussian blue. 【0028】 The particle size of the adsorbent powder 2 can be selected as appropriate, but for example, in the case of liquid treatment such as wastewater, it is preferable to use powders with an average particle size of 1 to 30 μm, and more preferably powders with an average particle size of 5 to 9 μm. If the average particle size of the activated carbon particles is smaller than 1 μm, the gaps between the activated carbon particles are too narrow, which tends to slow down the filtration treatment speed. On the other hand, if the average particle size of the activated carbon particles is larger than 30 μm, the gaps between the activated carbon particles become wider, and the substance to be adsorbed is not adsorbed onto the activated carbon but is more likely to pass through the gaps between the activated carbon particles to the secondary side. The average particle size of the adsorbent powder 2 refers to the average value of the projected circle equivalent diameter (the diameter of a circle equal to the projected area of ​​the particle) of each particle, and can be determined by measuring the particle size distribution using a laser diffraction / scattering particle size distribution analyzer (for example, product LA-960V2 series, manufactured by Horiba, Ltd.) and determining the particle size when the cumulative volume corresponds to 50%. 【0029】 (Powder supply device) The powder supply device 3 can be any known quantitative supply device, such as a rotary feeder or a table feeder, which can be appropriately selected and used. The powder supply device 3 in the illustrated example is a table feeder equipped with a turntable, a hopper for dropping and supplying adsorbent powder 2 onto the upper surface of the turntable, a scraper (not shown) for scraping the adsorbent powder 2 from the turntable to a discharge chute at a predetermined position in the circumferential direction of the turntable, and a blower for supplying compressed air CA to the discharge chute. The adsorbent powder 2 dispensed from the hopper is then pneumatically transported to the addition section 5. Reference numeral 14 indicates a transport bag, such as a flexible container bag, containing the adsorbent powder. 【0030】 The total amount dispensed by the powder supply device 3 is equal to the total amount of adsorbed powder 2 attached to the filtration membrane 22m (the target amount of adsorbed powder 2 deposited per unit area (g / m²)). 2 (This can be expressed as the product of the area of ​​the primary side surface of the filtration membrane 22m) 【0031】 (Dispersion liquid / Dispersion liquid supply source) The dispersion D can be selected as appropriate, for example, as the solvent or dispersion medium of the liquid to be treated A (for example, clean water if the liquid to be treated A is wastewater), or as the liquid to be treated A itself. The dispersion supply source 4 is not particularly limited as long as it can supply the required amount of dispersion D as needed, and may simply be a dispersion storage tank 4a that stores dispersion D, as shown in the illustrated example. 【0032】 (Additional part) The additive section 5 is not particularly limited as long as it can add the adsorbent powder 2 to the dispersion liquid D. For example, the additive section 5 can be a mixing pipe (T-tube) through which the dispersion liquid D flows, into which the adsorbent powder 2 is blown together with air (or simply supplied by gravity) to merge. Reference numeral 4b indicates a supply path that supplies the dispersion liquid D stored in the dispersion liquid storage tank 4a to the additive section 5. 【0033】 (Dilution section) The dilution section 7 is not limited as long as it can dilute the primary slurry S1 discharged from the intermediate line mixer 6 by adding the dispersion liquid D. The dilution section 7 may be a dilution tank to which the primary slurry S1 discharged from the intermediate line mixer 6 is supplied, as shown in Figure 2, and additional dispersion liquid D is also supplied. In this case, a slurry S2 for forming a deposit layer is continuously produced in the dilution tank. The dilution section 7 may be a mixing pipe to which the primary slurry S1 discharged from the intermediate line mixer 6 is supplied to a flow path through which additional dispersion liquid D flows, as shown in Figures 1 and 4. As shown in Figure 4, the intermediate line mixer 6 and the dilution section 7 may be provided in multiple stages. Reference numeral 4c indicates a supply path that supplies the dispersion liquid D stored in the dispersion liquid storage tank 4a to the dilution section 7. 【0034】 When supplying dispersion liquid D to multiple locations such as the additive section 5 and the dilution section 7, the dispersion liquid may be supplied from a common dispersion liquid supply source 4 as shown in the illustrated example, or it may be supplied from separate dispersion liquid supply sources 4 provided for each of the additive section 5 and the dilution section 7 (not shown). In the latter case, the type of dispersion liquid D may be changed for each dispersion liquid supply source 4. 【0035】 (Intermediate line mixer / Outlet line mixer) The intermediate line mixer 6 is not particularly limited as long as it forcibly agitates the liquid passing through the flow path with shear action while spatially constraining it, and there is no stagnation. Examples include so-called static mixers (for example, those with stationary baffles or obstacles inside the piping that change the direction of flow), jet mixers, injector mixers, and dynamic mixers with rotating agitators such as rotating agitator blades inside the piping. 【0036】 The slurry delivery unit 120 supplies the slurry S2 for deposit formation, which is continuously produced in the slurry production unit 110, to the primary side of the filtration membrane 22m via the delivery line mixer 8 without causing any stagnation. 【0037】 The output line mixer 8 can be selected from the same types as the intermediate line mixer 6, and may be the same type of line mixer as the intermediate line mixer 6, or a different type of line mixer. 【0038】 (defoaming device) When the adsorbent powder 2 is supplied by the powder supply device 3, air may be mixed into the primary slurry S1. If such air is mixed into the slurry S2 for deposit formation, defects such as bubbles, clumps, and cracks may be formed on the surface or within the deposit layer 2K, starting from the air. Therefore, as shown in Figures 1, 2, and 4, a defoaming device 11 can be provided between the additive section 5 and the dilution section 7 to remove air from the primary slurry S1. The defoaming device 11 is not particularly limited as long as it can remove bubbles, but it is preferable that it does not retain bubbles or has almost no bubbles. As such a defoaming device 11, a cyclone-type (centrifugal separation type) defoaming device that separates gas and liquid during the process of the primary slurry S1 flowing down in a spiral is suitable. As shown in Figure 2, if the dilution section 7 is a storage tank, the storage tank can also serve as a defoaming device, although its bubble removal performance is inferior. 【0039】 (pump) Metering pumps 12 and 13 can be appropriately placed for at least one of the supply of dispersion liquid D to the additive section 5 and the supply of primary slurry S1 to the dilution section 7. For example, in the example shown in Figure 3, a supply pump 13 can be provided in the flow path between the additive section 5 and the delivery line mixer 8, and configured to draw dispersion liquid D from the dispersion liquid supply source 4 to the additive section 5, and to draw in the dispersion liquid D to which the adsorbent powder 2 has been added in the additive section 5 and pump it under pressure to the delivery line mixer 8. In this case, the supply of dispersion liquid D to the additive section 5 and the pumping of the dispersion liquid D to which the adsorbent powder 2 has been added to the delivery line mixer 8 can be performed with a single pump, and the mixing of the dispersion liquid D and the adsorbent powder 2 can be promoted by the stirring action of the supply pump 13 upstream of the delivery line mixer 8. 【0040】 Furthermore, as shown in the examples in Figures 1, 2, and 4, if a defoaming device 11 is included, an additive pump 12 can be provided on both the upstream and downstream sides of the defoaming device 11. When an additive pump 12 is provided on the upstream side of the defoaming device 11, as shown in the illustrated example, the additive pump 12 can be provided in the flow path between the additive section 5 and the intermediate line mixer 6, and the additive pump 12 can be configured to draw the dispersion liquid D from the dispersion liquid supply source 4 to the additive section 5, and to draw the dispersion liquid D with the adsorbent powder 2 added from the additive section 5 and pump it to the intermediate line mixer 6. In this case, the supply of dispersion liquid D to the additive section 5 and the pumping of the dispersion liquid D with the adsorbent powder 2 added to the intermediate line mixer 6 can be performed with a single pump, and the mixing of the dispersion liquid D and the adsorbent powder 2 can be promoted by the stirring action of the additive pump 12 on the upstream side of the intermediate line mixer 6. 【0041】 On the other hand, if a supply pump 13 is provided downstream of the defoaming device 11, as shown in the illustrated example, the supply pump 13 can be provided in the flow path downstream of the dilution section 7. The supply pump 13 can be used to draw the dispersion liquid D from the dispersion liquid supply source 4 to the dilution section 7, and to draw the primary slurry S1, which has been defoamed by the defoaming device 11, into the dilution section 7 for dilution, and then pump it under pressure to the discharge line mixer 8 of the slurry discharge section 120. This allows the supply of additional dispersion liquid D and primary slurry S1 to the dilution section 7 and the pumping of the diluted slurry S2 for deposit layer formation to the discharge line mixer 8 to be performed with a single pump, and the stirring action of the supply pump 13 upstream of the discharge line mixer 8 can be used to promote the mixing of the additional dispersion liquid D and primary slurry S1. 【0042】 (filtration section) The filtration unit 10 is not particularly limited as long as it filters the entire volume of the liquid to be treated A by a filtration membrane 22m. As an example, the filtration unit 10 shown in Figure 5 is described as having a liquid to be treated storage tank 17 for storing the liquid to be treated A, a strainer 19 for removing impurities from the liquid to be treated A supplied from the liquid to be treated storage tank 17 via a first pipe 31, a filtration device 20 to which the liquid to be treated A from which impurities have been removed by the strainer 19 is supplied via a second pipe 32, and a third pipe 35 for discharging the filtrate B discharged from the filtration device 20. Reference numeral 18a indicates a liquid to be treated supply pump that delivers the liquid to be treated A stored in the liquid to be treated storage tank 17. 【0043】 (filtration device) The filtration device 20 includes a filtration container 21 that houses a filtration filter 22. A cake discharge chute 21S is provided at the bottom of the filtration container 21, and a cylindrical filtration filter housing is located above the cake discharge chute 21S. Reference numeral 34 indicates a fifth pipe 34 for discharging the cake K, adsorbent powder 2, washing liquid C, etc., which are discharged via the cake discharge chute 21S. The filtration filter 22 has a cylindrical body 22s with permeable holes for the filtrate B formed in its outer peripheral wall and a filtrate passage 22r formed inside, and a filtration membrane 22m wrapped around the outer peripheral surface of the cylindrical body 22s. It is preferable to use a pleated filter for the filtration membrane 22m, which is formed into a cylindrical shape by bending a flat filter material in a zigzag pattern (bellows-like) and wrapping it around the outer peripheral surface of the cylindrical body 22s in order to secure a surface area (filtration area). A supply port 24 for the liquid to be treated A is provided at an appropriate location in the filtration container 21, and the filtrate passage 22r of the filtration filter 22 is connected to the third pipe 35 via a discharge passage 25 that penetrates the filtration container 21. 【0044】 (filtration membrane) The filtration membrane 22m can be appropriately selected from filter materials (filter paper, filter cloth, etc.) having pore sizes that do not allow the adsorbed powder 2 forming the deposition layer 2K to pass through. If there are substances to be separated that cannot be separated by the adsorbed powder 2 or its deposition layer 2K, it is desirable to use a filtration membrane 22m that can separate those substances. The filtration membrane 22m can be a porous membrane formed by melting resin and forming it into a film, or a fibrous membrane formed by laminating resin fibers using methods such as electrospinning, electroblowing, and meltblowing. Both can be used, but the fibrous membrane is preferred because it has a larger surface area and higher porosity, resulting in excellent fluid permeability and excellent adhesion to the deposition layer 2K. The pore structure of the porous membrane can be appropriately selected from known structures such as lace-like, nodal, and fibril-like structures. 【0045】 The material of the 22m filtration membrane is not particularly limited and can be appropriately selected from known organic materials such as polyester (PEs), polyethersulfone (PES), polytetrafluoroethylene (PTFE), polyamide (PA), polyphenylene sulfide (PPS), polyethylene (PE), ultra-high molecular weight polyethylene (UPE), polyvinylidene fluoride (PVDF), polypropylene (PP), polyimide (PI), polycarbonate (PC), and polymethyl methacrylate (PMMA), as well as inorganic materials such as ceramics (alumina, glass, etc.) and metals (stainless steel, titanium, etc.). 【0046】 The filtration membrane 22m may be single-layered or multi-layered, and may be a symmetric or asymmetric membrane. Furthermore, the filtration membrane 22m may be a hydrophilic or hydrophobic membrane. 【0047】 The pore size of the filtration membrane 22m can be determined as appropriate, but for example, approximately 0.01 μm to 0.3 μm (MF membrane), 0.01 μm or less (UF membrane), and 1 nm to 2 nm (NF membrane) can be suitably used. Note that the pore size of the filtration membrane 22m refers to the maximum pore size calculated based on the bubble point measured by the bubble point test method specified in JIS K 3832-1990. If the filtration membrane 22m is a fiber membrane, the fiber diameter (equivalent to the projected area circle diameter, Heywood diameter; the same applies hereinafter) can be determined as appropriate, but is preferably 1 nm to 3 μm, and more preferably 500 nm or less. 【0048】 The removal rate of the 22m filter membrane is determined by the thickness, pore size, and pore size distribution of the 22m filter membrane, and can be selected appropriately. For example, if the pore size is similar to that of an MF membrane, a membrane with a removal rate of 99.95% or higher for particles of 0.1 to 0.3 μm can be used. 【0049】 (sedimentary layer) The deposited layer 2K is one in which the adsorbed powder 2 maintains its aggregate state (layer shape) and adhesion to the filter membrane 22m through intermolecular forces (van der Waals forces, electrostatic forces, hydrogen bonds), and is not bonded with adhesives, binders, or welds, meaning that it is susceptible to cracking, peeling, or collapse due to external forces. Such a deposited layer 2K can be formed as a cake layer on the primary side of the filter membrane 22m by filtering the slurry S2 for deposit formation through the filter membrane 22m. The deposited layer 2K may be dry or moistened with water or the like. 【0050】 By filtering the liquid A to be treated through the deposited layer 2K, the adsorbent substance in the liquid A can be adsorbed onto the adsorbent powder 2. Therefore, the thickness of the deposited layer 2K can be appropriately set according to the adsorption capacity of the adsorbent powder 2. For example, the thickness of the deposited layer 2K can be about 1 to 10 mm, preferably about 1.5 to 5 mm, more preferably 2 to 5 mm, and particularly preferably about 3 to 5 mm. If the thickness of the deposited layer 2K is too thin, the adsorbent substance will not be adsorbed onto the adsorbent powder 2, and will easily pass through the gaps between the adsorbent powder particles to the secondary side. For example, when adsorbing and removing PFOS, if activated carbon particles with an average particle size of about 10 μm are used as the adsorbent powder 2, the thickness of the deposited layer 2K can be 1.5 mm or more, preferably 3 mm or more. 【0051】 (Filter cleaning device) There is a limit to the amount of adsorption by the adsorbed powder 2 on the deposited layer 2K, and due to filtration, a cake K of suspended particles in the treated liquid A accumulates on the outer surface of the deposited layer 2K (see Figure 6), and the pores of the filter membrane 22m also become clogged. Therefore, when the filtration capacity decreases to a predetermined level, it is desirable to peel off the deposited layer 2K and the cake K and discharge them from the filtration device 20. For this reason, the filtration system 1 shown in Figure 5 is provided with a filter cleaning device 30 for peeling off the deposited layer 47 and the cake K. More specifically, the filter cleaning device 30 has a cleaning liquid storage tank 41 for storing cleaning liquid C, a spraying unit 23 for spraying the cleaning liquid C toward the primary side surface of the filter filter 22 in the filtration container 21, and a cleaning liquid supply pump 18c for pressurizing the cleaning liquid C stored in the cleaning liquid storage tank 41 to the spraying unit 23 via the fourth pipe 33. For the purpose of circulating the cleaning fluid C, it is preferable that the fifth pipe 34, which has a valve V5, is connected to the cleaning fluid storage tank 41. 【0052】 As the cleaning solution C, a purified liquid such as tap water may be used. However, since the cleaning solution C used to clean the filtration filter 22 needs to be purified by filtration or other means, the liquid to be treated A may be used from the viewpoint of economy and efficiency. It is preferable to mix cleaning particles F into the cleaning solution C. The cleaning particles F can be selected as appropriate, and for example, beads such as spherical plastic beads or spherical perlite beads, spherical sponges such as spherical PVC sponges, or sand such as silica sand can be used. 【0053】 While multiple spraying units 23 can be provided to apply the cleaning solution C to the entire outer surface of the filter 22, if the filter 22 is cylindrical as shown in the illustrated example, it is preferable to configure the filter 22 to be rotatable around its axis by a motor M. 【0054】 Furthermore, in the illustrated example of the filter cleaning apparatus 30, a granular material classifier 40 is included to classify cleaning particles F from the waste liquid U in the cleaning liquid storage tank 41 for reuse of the cleaning liquid C. The cleaning liquid storage tank 41 and the granular material classifier 40 are connected via a granular material recovery pipe 39 having a waste liquid transport pump. The cleaning particles F classified by the granular material classifier 40 are returned to the cleaning liquid storage tank 41. The granular material classifier 40 is also connected via a waste liquid discharge pipe 37 to a dewatering apparatus 42 consisting of a bag filter, filter press, etc. To return the liquid separated by the dewatering apparatus 42 to the cleaning liquid storage tank 41 via a waste liquid return pipe 38, the dewatering apparatus 42 and the second pipe 32 are connected via a waste liquid return pipe 38 having a waste liquid return pump 18e. The waste liquid return pipe 38 may be connected to an appropriate location among the following: downstream of valve V1 in the second pipe 32, the filtration container 21, the fifth pipe 34, or the washing liquid storage tank 41. 【0055】 Furthermore, in the illustrated filter cleaning device 30, a valve V2 is provided in the third pipe 35 for the purging process described later, and a compressor 46 is connected between the valve V2 in the third pipe 35 and the filtration device 20 via an air supply pipe 36 having a valve V3. 【0056】 (Deposited layer formation method) In the filtration system 1 described above, a slurry S2 for forming a deposit layer is continuously produced in the slurry production unit 110 of the slurry supply unit 100 using the dispersion liquid D and the adsorbent powder 2. This slurry S2 for forming a deposit layer, continuously produced in the slurry production unit 110, is supplied to the primary side of the filtration membrane 22m in the filtration unit 10 via the delivery line mixer 8 without being allowed to accumulate by the slurry delivery unit 120. This allows a deposit layer 2K of the adsorbent powder 2 to be formed on the primary side surface of the filtration membrane 22m. 【0057】 For example, if the slurry supply unit 100 shown in Figure 1 is used in the filtration system 1 shown in Figure 5, first, valve V1 installed in the second pipe 32 and valve V2 installed in the third pipe 35 are opened, and the other valves V3 to V5 are closed. Then, the powder supply device 3, the addition pump 12 and the supply pump 13 are started to supply the adsorbed powder 2 stored in the hopper and the dispersion liquid D stored in the dispersion liquid storage tank 4a to the addition unit 5. 【0058】 In the additive section 5, the adsorbent powder 2 is supplied to the dispersion liquid D, then pumped through the additive pump 12 and the intermediate line mixer 6, and forcibly stirred by the additive pump 12 and the intermediate line mixer 6 to produce the primary slurry S1. At this time, by using the intermediate line mixer 6, even if the adsorbent powder 2 is agglomerated, it is possible to break it down while mixing, thereby making the adsorbent powder 2 into single particles, and further improving the dispersibility of the adsorbent powder 2 in the dispersion liquid D in the primary slurry S1. 【0059】 In the illustrated example, the primary slurry S1 is supplied to the dilution section 7 after the air has been removed via the defoaming device 11. In the dilution section 7, the air-removed primary slurry S1 is added in a predetermined ratio to the dispersion liquid D, which is separately pumped to the filtration section 10, to continuously produce the slurry S2 for deposit formation. The dilution ratio can be determined as appropriate, but the concentration of the primary slurry S1 is preferably 7% by weight or less, and the concentration of the slurry S2 for deposit formation is preferably about 0.5 to 3% by weight, and particularly preferably about 0.5 to 2% by weight. 【0060】 The slurry S2 for forming the deposit layer, prepared in the dilution section 7, is pumped by the supply pump 13 through the delivery line mixer 8 to the filtration device 20 of the filtration section 10 without any stagnation. In the example shown in Figure 5, the slurry S2 for forming the deposit layer is supplied to the second pipe 32, but it can also be supplied to the first pipe 31 as long as the slurry S2 for forming the deposit layer does not stagnate. In the filtration device 20, the slurry S2 for forming the deposit layer is supplied to the primary side of the filtration membrane 22m without any stagnation, and the entire amount is filtered. As a result, the adsorbed powder 2 in the slurry S2 for forming the deposit layer is deposited on the primary side of the filtration membrane 22m to form a deposit layer 2K (see Figure 6), and the filtrate J (dispersion D) that has permeated through the filtrate passage 22r of the filtration filter 22 is discharged outside the filtration system 1 via the third pipe 35. By employing this method of supplying the slurry S2 for deposit formation, even if there are aggregates or clumps of adsorbed powder 2 in the slurry S2, the forced stirring by the delivery line mixer 8 makes it easier to break them down into single particles. Furthermore, since the entire amount is filtered by the filtration membrane 22m without any retention, it is possible to create a deposit layer 2K with a denser and more homogeneous particle packing structure on the primary side of the filtration membrane 22m than in conventional methods. In the example shown in Figure 1, two line mixers are used, but as shown in the examples in Figures 3 and 4, the number of line mixers can be one or two or more. 【0061】 The supply flow rate of the slurry S2 for deposit formation is preferably 17 to 28 L / min (approximately 500 to 800 LMH in permeate flux). Furthermore, the differential pressure between the primary and secondary sides of the 22 m filtration membrane is preferably approximately 5 to 30 kPa. 【0062】 Once the accumulation of the adsorbed powder 2 on the filtration membrane 22m is complete, the powder supply device 3, the addition pump 12, and the supply pump 13 are stopped to terminate the accumulation layer formation operation. The accumulation layer formation operation can be terminated automatically or manually. The accumulation layer formation operation may be terminated after a predetermined time has elapsed using a timer, or pressure gauges (not shown) may be installed in the primary and secondary flow paths of the filtration device 20 to measure the internal pressure, and the operation may be terminated when the differential pressure between the primary and secondary sides of the filtration device 20 exceeds a predetermined value. 【0063】 (filtration method) In this filtration system, the liquid to be treated A can be filtered after forming a deposit layer 2K. For example, in the filtration system 1 shown in Figure 5, without changing the opening or closing of valves V1 to V5, the liquid to be treated supply pump 18a installed in the liquid to be treated storage tank 17 is activated, and the liquid to be treated A is supplied to the filtration container 21 of the filtration device 20 via the first pipe 31, strainer 19, and second pipe 32. The flow velocity of the liquid to be treated A supplied to the filtration container 21 is preferably about 0.001 m / s to 0.004 m / s (FLUX of 50 LMH to 200 LMH), and more preferably about 0.0017 m / s to 0.0025 m / s. 【0064】 In this way, the liquid to be treated A that reaches the filtration container 21 is completely filtered by the filtration membrane 22m, and the filtrate B is discharged outside the system through the discharge passage 25 and the third pipe 35. On the other hand, the adsorbed substances in the liquid to be treated A are adsorbed by the deposit layer 2K formed on the primary side of the filtration membrane 22m, and solid matter from the liquid to be treated A accumulates on the outer surface of the deposit layer 2K to form a cake K. 【0065】 Once the filtration process is complete, the filtration operation can be terminated by stopping the liquid supply pump 18a. The filtration operation can be terminated automatically or manually. For example, to stop the filtration operation when the filtration membrane 22m becomes clogged (fouled), pressure gauges (not shown) for measuring internal pressure can be installed in the primary and secondary flow paths of the filtration device 20, and the filtration operation can be terminated when the differential pressure between the primary and secondary sides of the filtration device 20 exceeds a predetermined value. Alternatively, the amount of filtrate B discharged per unit time can be measured using a flow meter (not shown), and the filtration operation can be terminated when the amount falls below a certain value. Furthermore, the filtration operation can be terminated after a predetermined time has elapsed since the start of the filtration process using a timer, or the thickness of the cake K can be measured, and the filtration operation can be terminated when it is determined that filtration is no longer possible when the cake thickness reaches approximately 1 mm to 2 mm. 【0066】 (Washing operation) After the filtration operation is complete, a washing operation can be performed to remove the filtrate B in the filtration membrane 22m, the sediment layer 2K adhering to the primary side surface of the filtration membrane 22m, and the cake K. For example, in the case of filtration system 1 shown in Figure 5, a gas-based purge process (also called a "gas purge process") can be performed. First, valves V1, V2, and V4 are closed, and valves V3 and V5 are opened to start the compressor 46. The pressure of the compressor 46 can be set to, for example, about 20 kPa. Then, the gas E (for example, air; if air is used, this is called air purging. Alternatively, other gases such as nitrogen may be used instead of air) sent from the compressor 46 is guided into the filtrate passage 22r via the air supply pipe 36. Immediately after the end of the filtration operation, filtrate B remains in the filtrate passage 22r, but the gas E sent to the filtrate passage 22r pushes the filtrate B from the inside to the outside of the filtration membrane 22m, sediment layer 2K, and cake K. As a result, filtrate B falls to the bottom of the filtration container 21 and is then returned to the washing liquid storage tank 41 through the fifth pipe 34. 【0067】 The time for this purging process can be, for example, 5 to 15 seconds. Specifically, if the air supply capacity of the compressor 46 is 2.5 L / min and the volume of the filtration container 21 (excluding the part below the lower end of the filtration membrane 22m) is 190 L, then it will take 190 L ÷ 2500 × 60 seconds = 4.56 seconds to complete the purging. Considering the time it takes to open valves V2 and V3, and the air resistance of the filtration membrane 22m, the purging process will be completed in approximately 10 seconds. This air purging process creates a state in which the inside of the filtration container 21 is filled with gas E, so that the primary side surface of the filtration membrane 22m can be washed in the gas during the subsequent washing process. 【0068】 A cleaning process can be performed following (or without) the purging process. In the cleaning process, the cake K formed on the deposited layer 2K and the deposited layer 2K are peeled off, returning the filtration membrane 22m to its initial state. In this cleaning process, valves V1, V2, and V5 are closed, and valves V3 and V4 are opened. The cleaning liquid supply pump 18c sends the cleaning liquid C stored in the cleaning liquid storage tank 41 through the fourth pipe 33 to the spraying section 23, and from the spraying section 23 it is blown out toward the filtration membrane 22m. The blown-out cleaning liquid C collides with the cake K and deposited layer 2K attached to the filtration membrane 22m, and the impact causes the cake K and deposited layer 2K attached to the filtration membrane 22m to peel off. If the cleaning liquid C contains cleaning particles F such as spherical plastic beads or spherical perlite beads, the peeling effect of the cake K and deposited layer 2K will be higher. 【0069】 The cake K and sediment layer 2K that fall into the cake discharge chute 21S of the filtration container 21 are sent to the washing liquid storage tank 41 via the fifth pipe 34, along with the washing liquid C. Alternatively, the detached cake K and sediment layer 2K may be sent to the washing liquid storage tank 41 immediately, or they may be accumulated in the cake discharge chute 21S and sent only after a certain amount has accumulated. 【0070】 In the cleaning process, similar to the purging process, gas can be supplied from the compressor 46 to the primary side of the filtration membrane 22m, and exhausted from the inside to the outside of the filtration membrane 22m. When performing the purging process, the compressor 46 should be kept running. As a result, the cake K formed in the deposited layer 2K is peeled off not only by the impact force of the cleaning solution C received from the outside of the filtration membrane, but also by the gas E discharged from the inside to the outside of the filtration membrane 22m. Therefore, compared to using only the cleaning solution C, it becomes easier to peel off the cake K and the deposited layer 2K. In addition, since the cleaning solution C is sprayed with the filtration container 21 filled with gas E, the impact force of the cleaning solution C is greater compared to the case where the filtration container 21 is filled with liquid (liquid to be treated A), resulting in a larger amount of peeling off of the cake K and the deposited layer 2K. 【0071】 After going through the processes described above, the washing liquid storage tank 41 is supplied with cake K, deposit layer 2K, washing particles F, liquid to be treated A, and filtrate B (collectively referred to as waste liquid U; the same applies hereinafter). In the case of the filtration system 1 shown in Figure 5, the washing liquid C can be reused. That is, the waste liquid transport pump 18b and the waste liquid return pump 18e are started, and the waste liquid U supplied to the washing liquid storage tank 41 is sent to the powder and granular material classifier 40 through the powder and granular material recovery pipe 39, where the washing particles F in the waste liquid U are recovered and returned to the washing liquid storage tank 41. The waste liquid U from which the washing particles F have been removed by the powder and granular material classifier 40 is sent to the dewatering device 42 via the waste liquid discharge pipe 37, where the solid components (cake K and adsorbed powder 2) and liquid components in the waste liquid U are separated. The cake K and deposit layer 2K separated by the dewatering device 42 are discharged outside this filtration system 1 and discarded. The liquid separated by the dewatering device 42 is returned to the washing liquid storage tank 41 via the waste liquid return pipe 38 and can be reused as washing liquid C in the washing process. In the illustrated example, the waste liquid return pipe 38 is connected upstream of the valve V1 in the second pipe 32, and by opening the valve V1, the liquid separated by the dewatering device 42 can be returned to the washing liquid storage tank 41 via the waste liquid return pipe 38, the second pipe 32, the filtration container 21 and the fifth pipe 34. 【0072】 Once the removal of the sediment layer 2K and cake K is complete, the washing operation can be terminated by stopping the washing liquid supply pump 18c. The washing operation can be terminated automatically or manually. The washing operation can be terminated after a predetermined time has elapsed using a timer. After the washing operation is completed, the system returns to the sediment layer 2K formation operation, and the filtration operation can be performed again by forming a new sediment layer 2K on the filtration membrane 22m of the filtration device 20. [Industrial applicability] 【0073】 This invention can be used in a filtration system for a liquid to be treated and as a method for forming an adsorbent powder deposit layer in a filtration membrane. [Explanation of symbols] 【0074】 1...Filtration system, 2...Adsorbent powder, 3...Powder supply device, 4...Dispersion liquid supply source, 4a...Dispersion liquid storage tank, 4b,4c...Dispersion liquid supply path, 5...Addition section, 6...Intermediate line mixer, 7...Dilution section, 8...Discharge line mixer, 22m...Filtration membrane, 10...Filtration section, 2K...Deposition layer, 11...Defoaming device, 12...Addition pump, 13...Supply pump, 14...Transport bag, S1...Primary slurry, S2...Slurry for forming the deposition layer, 17...Treatment liquid storage tank, 18a,18b,18c,18e...Pumps, 19...Strainer, 20...Filtration device, 21...Filtration container, 23...Spraying section, 24...Supply port, 25...Discharge path, 30...Filter cleaning device, 31...First Piping, 32...Second piping, 33...Fourth piping, 34...Fifth piping, 35...Third piping, 36...Air supply pipe, 37...Waste liquid discharge pipe, 38...Waste liquid return piping, 39...Powder and granular material recovery pipe, 40...Powder and granular material classification device, 41...Washing liquid storage tank, 42...Dewatering device, 46...Compressor, 22r...Filtrate passage, A...Liquid to be treated, B...Filtrate, CA...Pressurized air, C...Washing liquid, D...Dispersion, E...Gas, F...Washing particles, J...Filtrate, K...Cake, U...Waste liquid, V1~V5...Valves, 100...Slurry supply unit, 110...Slurry production unit, 120...Slurry delivery unit, TD...Thickness direction, IS...Secondary side (inside in the thickness direction), OS...Primary side (outside in the thickness direction).

Claims

[Claim 1] It includes a slurry supply unit that supplies a slurry for forming a deposition layer in which adsorbent powder is dispersed in a dispersion liquid, After supplying the slurry for forming the deposition layer from the slurry supply unit to the primary side of the filtration membrane and performing total filtration, a deposition layer of the adsorbed powder is formed on the primary side surface of the filtration membrane, In a filtration system in which the liquid to be treated is supplied to the primary side of the filtration membrane to perform total filtration, The slurry supply unit comprises a slurry production unit that continuously produces the slurry for forming the deposition layer using the dispersion and the adsorbent powder, and a slurry delivery unit that supplies the slurry for forming the deposition layer, which is continuously produced in the slurry production unit, to the primary side of the filtration membrane via a delivery line mixer without stagnation. A filtration system characterized by the following features. [Claim 2] The slurry preparation unit is, A powder supply device for quantitatively supplying the adsorbed powder, A dispersion supply source that supplies the aforementioned dispersion, An additive unit adds the adsorbent powder supplied in a fixed quantity from the powder supply device to the dispersion supplied in a fixed quantity from the dispersion supply source, An intermediate line mixer mixes the dispersion liquid to which the adsorbent powder has been added in the additive section to produce a primary slurry, The system includes a dilution unit that prepares the slurry for forming the deposition layer by adding the dispersion to the primary slurry discharged from the intermediate line mixer and diluting it, The filtration system according to claim 1. [Claim 3] A defoaming device for the primary slurry is interposed in the flow path between the additive section and the dilution section. The filtration system according to claim 2. [Claim 4] The slurry preparation unit has a supply pump in the flow path downstream of the dilution unit. The supply pump is configured to draw the dispersion from the dispersion supply source to the dilution section, and to draw the primary slurry, which has been defoamed by the defoaming device, into the dilution section for dilution, and then pump it under pressure to the discharge line mixer of the slurry discharge section. The filtration system according to claim 3. [Claim 5] The slurry preparation unit has an additive pump in the flow path between the additive unit and the intermediate line mixer. The addition pump is configured to draw the dispersion from the dispersion supply source to the addition section, and to draw the dispersion with the adsorbent powder added from the addition section and pump it under pressure to the intermediate line mixer. A filtration system according to any one of claims 2 to 4. [Claim 6] In a method for forming a deposit layer of adsorbent powder on the primary side surface of a filtration membrane by supplying a slurry for forming a deposit layer in which adsorbent powder is dispersed in a dispersion liquid to the primary side of a filtration membrane and performing total filtration, The slurry for forming the deposition layer is continuously prepared and supplied using the dispersion and the adsorbent powder, and this continuously prepared slurry for forming the deposition layer is supplied to the primary side of the filtration membrane via a delivery line mixer without stagnation. A method for forming a deposit layer of adsorbed powder in a filtration membrane, characterized by the above.

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