Microplastic recovery system

Abstract

A microplastic recovery system (1) according to one embodiment of the present invention is a microplastic recovery system for recovering microplastics from environmental water, comprising an environmental water line (10) through which the main body of environmental water is distributed, a cyclone separator (20) disposed in the environmental water line (10) and separating concentrated water with an increased amount of microplastics from the main body of environmental water, a discharge line (30) for discharging concentrated water from the cyclone separator (20), and a solid recovery unit (40) disposed in the discharge line (30) and recovering microplastics from the concentrated water.

Description

Technology Field

[0001] The present invention relates to a microplastic recovery system. The present application claims priority based on Japanese Patent Application No. 2022-148514 filed on September 16, 2022, and incorporates the contents thereof herein by reference. Background Technology

[0002] Plastics account for a significant portion of marine debris and are becoming an increasingly significant threat. In particular, addressing marine pollution caused by floating pollutants, including microplastics, has become a critical task. Therefore, a system for removing floating pollutants, such as microplastics, from environmental water used as ballast water in ships has been proposed (see, for example, Patent Document 1). Prior art literature

[0003] Japanese Patent Publication No. 2022-67738 The problem to be solved

[0004] On ships, environmental water, such as seawater, is drawn into the vessel for use as cooling water for the main engine or as ballast water. The amount of environmental water drawn into the vessel during navigation is vast. There is a need for technology that can recover suspended pollutants, including microplastics, contained in this environmental water and contribute to the improvement of aquatic environments such as oceans, lakes, and rivers.

[0005] Generally, the recovery of suspended contaminants is carried out by a filter system; however, in filter systems, pressure loss gradually increases as suspended contaminants accumulate. For this reason, in systems using filters, measures are sometimes taken such as preparing multiple filter series and switching between them to continue filtration continuously.

[0006] Meanwhile, it is necessary to supply a stable flow rate of the environmental water drawn into the vessel for each application. For example, fluctuations in the flow rate of the main cooling water must be avoided because they have a negative impact on the performance and safety of the main cooling water. For this reason, it is difficult to apply filter systems that cause flow rate fluctuations due to pressure loss or flow path switching.

[0007] For this reason, the present invention aims to provide a microplastic recovery system capable of suppressing the influence on the flow rate of the main product and securing a stable flow rate. means of solving the problem

[0008] A microplastic recovery system according to one embodiment of the present invention is a microplastic recovery system for recovering microplastics from environmental water, comprising: an environmental water line through which the main body of environmental water is distributed; a cyclone separator disposed in the environmental water line and separating concentrated water with an increased amount of microplastics from the main body of environmental water; a discharge line for discharging concentrated water from the cyclone separator; and a solid recovery unit disposed in the discharge line and recovering microplastics from the concentrated water.

[0009] In the microplastic recovery system described above, the concentrated water discharged from the discharge line may be a heavy fraction separated by centrifugal separation.

[0010] In the microplastic recovery system described above, the discharge line may recirculate the water that has passed through the solid recovery section to the downstream side of the cyclone separator of the environmental water line.

[0011] In the microplastic recovery system described above, the flow rate of the concentrated water discharged from the cyclone separator may be 5% or less of the flow rate of the environmental water introduced into the cyclone separator.

[0012] The microplastic recovery system described above may be placed in the environmental water line or the cyclone separator and may further be equipped with a flow state detector that detects the flow rate or pressure of the environmental water. Effects of the invention

[0013] According to the present invention, a microplastic recovery system that does not require the stopping of alcohol can be provided. Brief explanation of the drawing

[0014] FIG. 1 is a schematic diagram showing the configuration of a microplastic recovery system according to a first embodiment of the present invention. Specific details for implementing the invention

[0015] 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 microplastic recovery system (1) according to one embodiment of the present invention.

[0016] The microplastic recovery system (1) is a system for recovering microplastics from environmental water (seawater, river water, lake water, etc.) and is used to separate and recover solids, mainly microplastics, from environmental water used in various demand facilities. Demand facilities that use environmental water from which microplastics are removed by the microplastic recovery system (1) typically include the main body of a ship or a main body cooling device. That is, environmental water can be used to cool the main body directly or indirectly.

[0017] A microplastic recovery system (1) comprises an environmental water line (10) through which the main body of environmental water is distributed, a cyclone separator (20) disposed in the environmental water line (10) and separating concentrated water with an increased amount of microplastics from the main body of environmental water, a discharge line (30) that discharges the concentrated water from the cyclone separator (20), and a solid recovery unit (40) disposed downstream of the discharge line (30) and recovering microplastics from the concentrated water.

[0018] The environmental water line (10) is a flow path that guides environmental water supplied by a pump, etc. not shown in the drawing, to the demand facility through a cyclone separator (20). The environmental water flowing through the environmental water line (10) is the main stream of environmental water passing through the microplastic recovery system (1). That is, more than half of the environmental water introduced to the demand facility through the microplastic recovery system (1) passes through the environmental water line (10).

[0019] The environmental water line (10) may be equipped with a flow state detector (11) that detects the flow state of the environmental water. The flow state detector (11) may be configured to detect the flow rate or pressure of the environmental water. The flow state detector (11) of this embodiment is a differential pressure gauge that detects the differential pressure before and after the cyclone separator (20). Based on the flow state detected by the flow state detector (11), the occurrence of blockage of the cyclone separator (20) that reduces the flow rate of the environmental water can be detected. Additionally, the flow state detector (11) may be placed in the cyclone separator (20).

[0020] The cyclone separator (20) introduces environmental water in a tangential direction into a cylindrical cyclone body (21), centrifugally separates solids containing microplastics contained in the environmental water, discharges the main water with reduced solid concentration, and separates the concentrated water with increased presence of microplastics and other solids to the lower part of the cyclone body (21). Accordingly, the concentrated water discharged from the cyclone separator (20) is a heavy fraction separated by centrifugal separation, that is, water with a higher concentration of solids that have a relatively large specific gravity or particle size and are subjected to a greater centrifugal force than the water (saltwater) which is the dispersion medium.

[0021] The discharge line (30) discharges concentrated water with a high concentration of microplastics from the bottom of the cyclone body (21) of the cyclone separator (20). The discharge line (30) may be equipped with an adjustment valve (31) to adjust the discharge amount of concentrated water from the cyclone separator (20) and further adjust the concentration of solids in the concentrated water. Additionally, the discharge line (30) may recirculate water that has passed through the solid recovery unit (40), i.e., water from which solids have been separated and removed, to the downstream side of the cyclone separator (20) of the environmental water line (10). The discharge line (30) of this embodiment has a recirculation pump (32) to increase the pressure of the water that has passed through the solid recovery unit (40) and to recirculate the water from which solids have been separated and removed to the environmental water line (10). Additionally, the discharge line (30) of this embodiment has a pressure switch (33) on the suction side of the recirculation pump (32). The pressure switch (33) can be used to detect blockage of the solid recovery unit (40) by detecting the negative pressure generated by the reflux pump (32) on the suction side when the pressure loss in the solid recovery unit (40) increases. Additionally, the discharge line (30) of this embodiment has a shut-off valve (34) on the upstream side of the solid recovery unit (40).

[0022] The amount of solids separated by the cyclone separator (20) does not vary significantly depending on the flow rate of the concentrated water, but if the flow rate of the concentrated water is too small, there is a risk that the solids will settle and cause clogging. As for the flow rate of the concentrated water discharged from the cyclone separator (20) by the discharge line (30), it is desirable to set it to the minimum flow rate that allows solids containing microplastics to flow and be discharged in order to suppress the reduction of the flow rate of the main stream on the downstream side of the environmental water line (10). Specifically, it is desirable that it be 5% or less of the environmental water introduced into the cyclone separator (20), and more desirable that it be 3% or less.

[0023] The solid recovery unit (40) separates and recovers solids containing microplastics from the concentrated water. The solid recovery unit (40) of the present embodiment has, for example, a filtration device (41) such as a strainer. When the water that has passed through the discharge line (30) is discharged outside the system, the solid recovery unit (40) may be a drainage mechanism capable of recovering solids containing microplastics by, for example, arranging a filter net, etc., or it may be configured to have a tank for storing the discharged concentrated water in order to recover microplastics by, for example, by coagulation sedimentation or flotation by bubbles.

[0024] In order to detect blockage of the filtration device (41), the solid recovery unit (40) preferably has a differential pressure gauge (42) that detects the differential pressure of the filtration device (41). When blockage of the filtration device (41) is detected by the differential pressure gauge (42), cleaning or replacement of the filter media of the filtration device (41) is performed. During this time, the control valve (31) and the shut-off valve (34) may be closed to stop the discharge of concentrated water from the cyclone separator (20) to the discharge line (30), and the flow rate of the concentrated water is relatively small and the discharge of the concentrated water may be temporarily stopped, allowing the environmental water to be passed stably. If the demand facility allows, the solid recovery unit (40) may be bypassed and the water may be returned to the environmental water line (10). In addition, the solid recovery unit (40) may have a plurality of filtration devices (41) that are selectively arranged in parallel to enable cleaning or replacement of the filter media of the filtration device (41) without stopping the water flow.

[0025] The microplastic recovery system (1) is a system for recovering microplastics from environmental water while prioritizing the original purpose of water intake, such as the main cooling water of a ship. It includes a mechanism for separating a heavy fraction of environmental water containing a large amount of microplastics (increased concentration) so as not to affect the flow rate of environmental water, and a mechanism for efficiently recovering microplastics from a heavy fraction of environmental water compressed into a small amount. The microplastic recovery system (1) is configured such that a cyclone separator (20) is installed in an environmental water line (10) through which the main body of environmental water flows to remove solid matter containing microplastics in the environmental water by centrifugal separation, and concentrated water with an increased amount of microplastics from the cyclone separator (20) is discharged to a discharge line (30). By doing so, fluctuations in the flow rate of environmental water that occur in the case of a filter system due to microplastic recovery are suppressed, and the flow rate of the environmental water line is stabilized. Therefore, when recovering microplastics from the main cooling water of a ship, the microplastics can be recovered while avoiding adverse effects on the main body. In the filter method, the interval for backwashing or replacing the filter varies depending on the concentration of suspended solids, such as microplastics, in the environment water; when the concentration of suspended solids is high, the interval is short (e.g., within a few hours), and when the concentration of suspended solids is low, the interval is long (e.g., within one week). In the cyclone method, there is no such interruption of operation, and continuous operation can be performed for any period during navigation.

[0026] The microplastic recovery system (1) can efficiently recover microplastics by reducing the amount of water filtered in the solid recovery section at the downstream end by concentrating the heavy fraction containing microplastics with relatively large specific gravity and particle size flowing through the environmental water line using a cyclone separator. In addition, since the flow rate of the solid recovery section is sufficiently smaller (5% or less) than the main flow rate of the environmental water, the impact on the flow rate of the environmental water line is very small even when the filter pressure drop increases or the filter is clogged, or when the discharge line (30) is blocked for filter replacement, so the environmental water can be circulated stably.

[0027] Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and various changes and modifications are possible. For example, the microplastic recovery system (1) may be installed at the downstream end of the demand facility to stably supply the flow rate of environmental water. Explanation of the symbols

[0028] 1 Microplastic recovery system 10 Environmental Water Line 11 Distribution status detector 20 cyclone separators 21 Cyclone Body 30 discharge lines 31 Adjustment Valve 32 Recirculation Pump 33 Pressure Switch 40 Solids Recovery Unit 41 Filtration device 42 Differential pressure gauge

Claims

Claim 1 A microplastic recovery system for recovering microplastics from environmental water, comprising: an environmental water line through which the majority of environmental water introduced into a demand facility flows; a cyclone separator disposed in the environmental water line and separating concentrated water of 5% or less of the flow rate of the introduced environmental water, which increases the amount of microplastics present in the main body of the environmental water; a discharge line for discharging the concentrated water from the cyclone separator; and a solid recovery unit disposed in the discharge line and having a filtration device for recovering microplastics from the concentrated water, wherein the discharge line recirculates water that has passed through the solid recovery unit to the downstream side of the cyclone separator of the environmental water line, and in the environmental water line, environmental water with a reduced solid concentration by the cyclone separator flows downstream of the cyclone separator. Claim 2 A microplastic recovery system according to claim 1, wherein the concentrated water discharged from the discharge line is a heavy fraction separated by centrifugal separation. Claim 3 A microplastic recovery system according to claim 1 or 2, wherein the discharge line has a reflux pump that pressurizes water passing through the solid recovery unit and recirculates it to the downstream side of the cyclone separator of the environmental water line. Claim 4 A microplastic recovery system according to claim 1 or 2, further comprising a flow state detector disposed in the environmental water line or the cyclone separator and detecting the flow rate or pressure of the environmental water.

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