Microplastic recovery system

Abstract

To provide a microplastic recovery system which is capable of selectively recovering microplastics from water in the environment.SOLUTION: A microplastic recovery system 1 according to one embodiment of the present invention involves recovering microplastics from water in the environment, the system being equipped with: a sedimentation / separation apparatus 20 for forming an upward flow in the environmental water, and causing the sedimentation and separation of the heavy fraction of suspended solids from the environmental water; and a filter apparatus 30 for filtering the environmental water from which the heavy fraction of the suspended solids has been removed by the sedimentation / separation apparatus 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a microplastics collection system. [Background technology]

[0002] Plastics account for a significant portion of marine litter and are becoming an increasingly serious threat. Addressing marine pollution by suspended pollutants, particularly microplastics, is an urgent issue. Generally, ships take in and discharge large amounts of environmental water for cooling and ballast water, but there are no effective methods for collecting and treating the suspended pollutants contained in the environmental water.

[0003] Therefore, it has been proposed to filter the environmental water taken into ships and recover floating pollutants such as microplastics (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-67738 Summary of the Invention [Problem to be solved by the invention]

[0005] In addition to microplastics, environmental water also contains suspended solids derived from the natural environment, such as sand, wood fragments, and seaweed fragments. Separating and recovering these naturally occurring suspended solids together with microplastics increases the amount of material recovered, leading to increased processing costs. Therefore, the present invention aims to provide a microplastic recovery system that can be widely applied to ships and other vessels and is capable of selectively recovering microplastics from environmental water. [Means for solving the problem]

[0006] A microplastic recovery system according to one embodiment of the present invention is a microplastic recovery system that recovers microplastics from environmental water, and is equipped with a sedimentation separator that forms an upward flow of environmental water and settles and separates heavy suspended solids from the environmental water, and a filter that filters the environmental water from which the heavy suspended solids have been removed by the sedimentation separator.

[0007] In the above-mentioned microplastics recovery system, the inlet flow velocity of the environmental water in the sedimentation separator may be 0.5 m / s or more and 1.5 m / s or less.

[0008] In the above-mentioned microplastic recovery system, the sedimentation separator may form a spiral upward flow of environmental water.

[0009] The above-mentioned microplastic recovery system may further include a primary separator upstream of the settling separator that separates the environmental water into environmental water with a reduced concentration of suspended solids and environmental water with an increased concentration of suspended solids, and the environmental water with an increased concentration of suspended solids that flows out from the primary separator may be introduced into the settling separator.

[0010] In the above-described microplastic recovery system, the heavy fraction of suspended solids may be discharged from the sedimentation separator below the environmental water inlet. [Effects of the Invention]

[0011] According to the present invention, a microplastic recovery system can be provided that can be widely applied to ships and the like and can selectively recover microplastics from environmental water. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a microplastics collection system according to a first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a microplastics collection system 1 according to one embodiment of the present invention.

[0014] The microplastic recovery system 1 is a microplastic recovery system that removes and recovers microplastics from environmental water (seawater, river water, lake water, etc.). The microplastic recovery system 1 may be installed on a path that takes in environmental water and introduces it into demand facilities such as ballast tanks and cooling devices, or it may be installed on a path that discharges used environmental water from demand facilities into the environment.

[0015] The microplastic recovery system 1 comprises a primary separator 10 that separates environmental water (raw water) into environmental water (low-concentration water) with a reduced concentration of suspended solids and environmental water (high-concentration water) with an increased concentration of suspended solids, a sedimentation separator 20 that forms an upward flow of the environmental water (high-concentration water), sediments and separates the heavy fraction of suspended solids (suspended solids with a high settling velocity) from the environmental water, and discharges intermediate treated water containing the light fraction of suspended solids, and a filter 30 that filters the environmental water (intermediate treated water) from which the heavy fraction of suspended solids has been removed by the sedimentation separator 20.

[0016] To enable these components to function, the microplastic recovery system 1 is equipped with a primary supply line 40 that supplies environmental water to the primary separator 10, a secondary supply line 50 that introduces the high-concentration water flowing out from the primary separator 10 into the sedimentation separator 20, a main discharge line 60 that discharges the low-concentration water flowing out from the primary separator 10 outside the system, an intermediate line 70 that introduces the intermediate treated water that has passed through the sedimentation separator 20 into the filter 30, a filtrate line 80 that discharges the filtrate that has passed through the filter 30, a sludge discharge line 90 that discharges the heavy fraction from the bottom of the sedimentation separator 20 outside the system, and a bypass line 100 that discharges the high-concentration water from the secondary supply line 50 to the main discharge line 60 or the filtrate line 80.

[0017] The primary separator 10 may be, for example, a cyclone separator that uses a flow path configuration to form a swirling flow and apply centrifugal force to the water to be treated, a continuous centrifuge that applies centrifugal force to the water to be treated by rotating a motor, or a separator that separates the water into low-concentration water and high-concentration water using a separation membrane. In Figure 1, the primary separator 10 is intended to be a cyclone separator.

[0018] The sedimentation separator 20 creates an upward flow with a higher settling velocity than the microplastics, allowing the heavy fraction of suspended solids, such as sand, which have a higher settling velocity than microplastics, to settle, while allowing the light fraction of suspended solids, which have a lower settling velocity, to flow out. In other words, the sedimentation separator 20 removes the heavy fraction from the concentrated water flowing out of the primary separator 10. The suspended solids are affected differently by the water flow depending on their specific gravity, shape, and size. For example, even if they have the same specific gravity, plate-shaped solids are more strongly affected by the water flow than lumpy solids and are more likely to be entrained by the water flow. The upward flow sedimentation separator 20 allows microplastics to be more easily entrained by the upward flow, enabling more effective separation of microplastics from soil particles, etc., compared to simple specific gravity separation or simple sedimentation separation.

[0019] The sedimentation separator 20 preferably creates a spiral upward flow of environmental water. Creating a circumferential flow can suppress particle shedding near the wall, which occurs in the case of a linear upward flow. This suppresses variations in the residence time of the environmental water and improves the separation effect of suspended solids. The inlet flow velocity of the environmental water in the sedimentation separator 20 is preferably 0.5 m / s or more and 1.5 m / s or less. For example, if the inlet of the sedimentation separator 20 is formed from a pipe with a nominal diameter of 25A and the main body of the sedimentation separator 20 is formed from a pipe with a nominal diameter of 100A, the flow velocity of the upward component will be between 0.042 m / s and 0.085 m / s. Creating an upward flow with such a swirling component achieves the effect of separating suspended solids by water flow in addition to gravity.

[0020] The filter 30 captures suspended solids in the intermediate treatment water. The filter 30 is preferably configured to easily recover the captured suspended solids, such as a strainer with a bucket-shaped filter material or a cartridge filter. The microplastic recovery system 1 may include multiple filters 30 arranged in parallel so that the filter material can be replaced while the system is running. Alternatively, a filter that backwashes the filter may be combined with a cartridge filter that filters suspended solids from the backwash water. The filter 30 or the flow paths before and after it may have a differential pressure gauge 31 to detect blockage of the filter 30. Detection of blockage of the filter 30 may be used to determine the need to use the bypass line 100.

[0021] The primary supply line 40 supplies environmental water to the primary separator 10. The primary supply line 40 may be provided with devices such as a pump, a flow meter, a pressure gauge, and a valve, as needed, which are not shown.

[0022] The secondary supply line 50 is configured to introduce the concentrate flowing out of the primary separator 10 into the settling separator 20. The secondary supply line 50 may be configured to have a shut-off valve 51 that shuts off the amount of concentrate flowing out of the primary separator 10.

[0023] The main discharge line 60 discharges the low-concentration water that flows out of the primary separator 10. The primary separator 10, which is a cyclone separator, does not clog and can always discharge environmental water with a reduced concentration of suspended solids into the main discharge line 60.

[0024] The intermediate line 70 introduces intermediate treated water, which has been treated in the sedimentation separator 20 to remove the heavy fraction of suspended solids from the concentrated water and has an increased ratio of microplastics among the suspended solids, into the filter 30. The intermediate line 70 preferably has a shutoff valve 71 that shuts off the flow path for maintenance of the filter 30.

[0025] In this embodiment, the filtrate line 80 introduces the filtrate from which suspended solids have been removed in the filter 30 into the main discharge line 60, but the filtrate may also be discharged separately from the system. For example, the filtrate line 80 may be equipped with a pressure pump (not shown) and configured to introduce the filtrate into the main discharge line 60. Alternatively, the main discharge line 60 may supply environmental water to a demand facility, and the filtrate line 80 may be configured to discharge the filtrate from the system. The secondary supply line 50 preferably has an adjustment valve 81 that adjusts the outflow rate of the filtrate from the filter 30, and therefore the outflow rate of the concentrated water from the primary separator 10 and the outflow rate of the intermediate treated water from the sedimentation separator 20.

[0026] The sludge discharge line 90 discharges the heavy fraction of settled suspended solids along with a small amount of wastewater from below the environmental water inlet of the sedimentation separator 20. The sludge discharge line 90 may have an adjustment valve 91 to adjust the discharge rate of environmental water containing suspended solids. The sludge discharge line 90 may intermittently discharge the heavy fraction of suspended solids, or may continuously discharge wastewater containing the heavy fraction at a flow rate sufficiently smaller than the flow rate of environmental water discharged from the sedimentation separator 20 to the intermediate line 70. The heavy fraction discharged from the sludge discharge line 90 may be treated as industrial waste, but since it is believed to be mainly composed of sand, it may also be released into the environment. Discharging the heavy fraction of suspended solids from the bottom of the sedimentation separator 20 through the sludge discharge line 90 prevents a decrease in the separation capacity of the sedimentation separator 20.

[0027] The bypass line 100 allows the concentrated water flowing out of the primary separator 10 to flow directly from the secondary supply line 50 to the filtrate line 80 when the filter 30 is clogged or while suspended solids are being collected from the filter 30. In the illustrated embodiment, the bypass line 100 has an automatic valve 101 that opens when the differential pressure gauge 31 detects a predetermined pressure. This allows for automatic detection of blockage of the filter 30 and necessary work, such as filter replacement, to be performed. Note that while environmental water can be directly introduced from the primary supply line 40 to the main discharge line 60 without passing through the primary separator 10, providing the bypass line 100 in the secondary supply line 50 allows the bypass line 100 to be constructed using piping with a relatively small diameter.

[0028] In the microplastic recovery system 1, the heavy fraction of suspended solids such as sand is separated by settling using the sedimentation separator 20 and then filtered using the filter 30, thereby increasing the proportion of microplastics in the suspended solids recovered by the filter 30. This reduces the load on the filter 30 and prevents clogging, allowing microplastics to be efficiently recovered from environmental water.

[0029] Furthermore, since the microplastic recovery system 1 is equipped with a primary separator 10 upstream of the sedimentation separator, primary treatment can be performed in the primary separator 10 to separate environmental water into low-concentration water with a low microplastic content and high-concentration water with a high microplastic content. As a result, the volume of high-concentration water with a high microplastic content is significantly reduced compared to the environmental water (for example, to 5% or less of the environmental water volume), allowing the sedimentation separator 20 to be made smaller in size relative to the amount of environmental water to be treated, thereby reducing the cost of the entire system. Furthermore, even if blockages occur in the sedimentation separator, filter, or the piping connecting them, the impact on the environmental water can be suppressed.

[0030] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. For example, the microplastics recovery system 1 does not need to include a primary separator, a primary supply line, and a main discharge line. Furthermore, the microplastics recovery system 1 may have any configuration, such as manually switching the bypass line. [Explanation of symbols]

[0031] 1. Microplastics Collection System 10 Primary separator 20 Sedimentation separator 30 Filter 31 Differential pressure gauge 40 Primary Supply Line 50 Secondary Supply Line 51 Shut-off valve 60 Main discharge line 70 Intermediate Line 71 Shut-off valve 80 Filtrate water line 81 Regulating valve 90 Sludge discharge line 91 Regulating valve 100 Bypass Line 101 Automatic valve

Claims

1. A microplastic recovery system for recovering microplastics from environmental water, a sedimentation separator that forms an upward flow of environmental water and sedimentation-separates a heavy fraction of suspended solids from the environmental water by the upward flow, a secondary supply line for supplying raw water to the sedimentation separator, an intermediate line through which intermediate treated water from which the heavy fraction of suspended solids has been removed by the sedimentation separator flows, a filter connected to the intermediate line for filtering the intermediate treated water, comprising The sedimentation separator has a cylindrical main body, a secondary supply line is connected below the central part of the cylindrical main body, an intermediate line is connected above the central part of the cylindrical main body, and an upward flow of environmental water is formed from the connection part of the secondary supply line toward the connection part of the intermediate line. A microplastic recovery system.

2. Further provided upstream of the sedimentation separator with a cyclone separator for separating environmental water into environmental water with a reduced concentration of suspended solids and environmental water with an increased concentration of suspended solids, The microplastic recovery system according to claim 1, wherein environmental water with an increased concentration of suspended solids flowing out from the cyclone separator is introduced into the sedimentation separator.

3. A primary supply line for supplying environmental water to the cyclone separator, a main discharge line for discharging environmental water with a reduced concentration of suspended solids from the cyclone separator, a filtered water line through which the filtered water that has passed through the filter flows, further comprising The microplastic recovery system according to claim 2, wherein the filtered water line returns the filtered water to the main discharge line.

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