JP2014171954A - Ballast water treatment system of marine vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ballast water treatment system of a marine vessel, which can be used for any ballast water including seawater, plain water, and brackish water, capable of improving the treatment function for microbes and bacteria with a low amount of ozone.SOLUTION: A ballast water treatment system 1 of a marine vessel removes microbes and bacteria from the water taken in at an anchorage site of the marine vessel so as to make ballast water. The system 1 includes a filter 6 capable of removing relatively large microbes from the water taken in the anchorage site by filtration, and an ozone injection apparatus 7 capable of removing relatively small microbes and bacteria from the water by injecting fine bubble ozone into the water filtered with the filter 6.

Description

  The present invention relates to a ballast water treatment system for a ship, and more particularly to a ballast water treatment system for a ship that produces ballast water by removing microorganisms and bacteria from water taken at a port of call of the ship.

  Ballast water is used to keep the ballast tank in the ship at sea, fresh water, brackish water (hereinafter referred to as sea Etc.) is taken in (when ballasting) and discharged when loading (when deballasting). The flora and fauna plankton and bacteria present in the seawater loaded as the ballast water may move along with the ship to other areas, thereby destroying the original ecosystem.

Against this background, the Ballast Water Management Convention was adopted at the international conference of the IMO (International Maritime Organization), and since 2009, ballast water treatment has become mandatory. Table 1 shows the ballast water discharge standards established by the IMO.

  Various methods are currently being researched and developed as ballast water treatment technologies. For example, Patent Document 1 discloses a method for detoxifying ballast water that removes microorganisms in untreated seawater and converts it into clean treated seawater. The seawater is relatively filtered by a filtration method using a filter. A microorganism separation process for removing large microorganisms, and then a chlorine-containing substance produced from the seawater and injected into the seawater to kill or sterilize the microorganisms or a substance having an oxidizing action on the seawater ( A method for detoxifying ballast water is disclosed, in which any one of the oxidizing substance addition processes for adding ozone or the like is performed, and the treated seawater is accommodated in a ballast tank.

  Then, the microorganism separation treatment by the filtration method and the treatment of any one of the microbial treatment by adding either the chlorination treatment to the ballast water after the treatment or the oxidation substance addition treatment for adding a substance having an oxidizing action to seawater are performed. Processing function is improved. Further, it is described that by selecting a filter mesh as an optimal mesh for removing microorganisms, a relatively large and wide range of microorganisms can be reliably captured and removed, and processing after capture can be simplified by backwashing or the like.

  However, in Patent Document 1, either one of a chlorination treatment or an oxidization substance addition treatment in which a substance having an oxidizing action is added to seawater is applied to the ballast water after the microorganism separation treatment by the filtration method. The treatment is obviously not usable for fresh water or brackish water. In addition, although ozone as an oxidizing substance addition treatment can be used for fresh water and brackish water, if ozone is injected into water as it is, most of it will be brackish and separated without remaining in the water, so a huge amount of ozone is required. Become. On the other hand, if the ozone contained in the ballast water is insufficient, it is presumed that the treatment function of microorganisms and bacteria is lowered.

  The present invention has been made in view of such circumstances, and can be used in any case where the ballast water is seawater, fresh water, or brackish water, and improves the treatment function of microorganisms and bacteria with a small amount of ozone. It is an object of the present invention to provide a ship ballast water treatment system that can be used.

  The present invention is a ballast water treatment system for a ship that produces ballast water by removing microorganisms and bacteria from the water taken at the port of call of the ship, and filters the water taken at the port of call of the ship. A filter capable of removing relatively large microorganisms from the water, and ozone injection capable of removing relatively small microorganisms and bacteria from the water by injecting ozone in the form of fine bubbles into the water filtered by the filter And a device.

  According to the present invention, a filter capable of removing relatively large microorganisms from the water taken at the port of call of the ship by filtering, and injecting ozone into the water filtered by the filter in the form of fine bubbles. And an ozone injection device capable of removing relatively small microorganisms and bacteria from the water, so that the water taken in the port of call of the ship is relatively large from the water by being filtered by the filter. Microorganisms (L size organisms) are completely removed, and ozone is injected into the water filtered by the filter in the form of fine bubbles by an ozone injection device, so that relatively small microorganisms (S size organisms) and bacteria are extracted from the water. Kind is killed.

  In addition, ozone can be used not only for seawater but also for all kinds of water including fresh water and brackish water, and since it can be produced using air as a raw material on board and has high decomposability, there is little risk of residual. In addition, when seawater is used, it is possible to prevent the propagation of organisms in the ballast tank by the oxidant generated by the reaction between ozone and the seawater.

  In addition, ozone can be made into microbubbles (fine bubbles) to increase solubility and increase efficiency, and the amount of ozone used can be reduced.

  In this way, by improving the filter performance and reducing the size of the ozone bubble, we were able to construct a system that not only met the IMO standards but could also meet the stricter standards that are expected in the future. .

  The ozone injection device preferably includes an ejector that injects ozone into water filtered by the filter, and a pump that sucks water into which ozone has been injected by the ejector.

  In this case, ozone is finely bubbled by the ejector and efficiently injected into the water filtered by the filter, and when the fine bubbles in the water into which ozone has been injected by the ejector is sucked by the pump, As a result, more stable fine bubbles can be generated.

  Moreover, it is preferable to inject | pour into the said filter at least one part of the water attracted | sucked with the said pump.

  In this case, since at least a part of the water sucked by the pump is injected into the filter, scale adhesion and biofilm formation on the filter are prevented.

  Further, it is preferable to further inject nitrogen into the water filtered by the filter in the form of fine bubbles.

  In this case, since nitrogen is further injected into the water filtered by the filter in the form of fine bubbles, an increase in the proportion of dissolved oxygen is suppressed. Thereby, reproduction of a living organism | raw_food can be suppressed by reducing the dissolved oxygen in a ballast tank.

  In addition, an oxygen recovery device that recovers oxygen by decomposing ozone not dissolved in the water from the water into which the ozone has been injected is provided, and an ozone raw material in which the oxygen recovered by the oxygen recovery device is injected by the ozone injection device It is preferable to reuse as.

  In this case, an oxygen recovery device is provided that recovers oxygen by decomposing ozone not dissolved in the water from the water into which the ozone has been injected, so that the oxygen recovered by the oxygen recovery device is the ozone injection device. Reused as a raw material for ozone injected in. As a result, it is possible to reduce the size of the device required for generating ozone and reduce the amount of power consumption.

  According to the present invention, a filter capable of removing relatively large microorganisms from the water by filtering the water in the harbor, and ozone from the water by injecting ozone into the water filtered by the filter in the form of fine bubbles. And an ozone injection device capable of removing relatively small microorganisms and bacteria, so that the water in the harbor is filtered by a filter to completely remove relatively large microorganisms (L size organisms) from the water, Ozone is injected into the water filtered by the filter in the form of fine bubbles by an ozone injection device, so that relatively small microorganisms (S size organisms) and bacteria are killed from the water.

  In addition, ozone can be used not only for seawater but also for all kinds of water including fresh water and brackish water, and since it can be produced using air as a raw material in a ship and has high decomposability, there is little risk of residual. In addition, when seawater is used, it is possible to prevent the propagation of organisms in the ballast tank by the oxidant generated by the reaction between ozone and the seawater.

  In addition, ozone can be made into microbubbles to increase solubility and increase efficiency, and the amount of ozone used can be reduced.

  In this way, by improving the filter performance and reducing the size of the ozone bubble, we were able to construct a system that not only met the IMO standards but could also meet the stricter standards that are expected in the future. .

It is explanatory drawing which shows the whole structure of the ballast water treatment system of the ship which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the whole structure of the ballast water treatment system of the ship which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows the cross section of a ship. It is explanatory drawing which shows the mode before and behind a process of L size organism. It is explanatory drawing which shows the mode before and behind a process of S size living thing.

(Embodiment 1)
FIG. 1 is an explanatory view showing the overall configuration of a ship ballast water treatment system 1 according to Embodiment 1 of the present invention, and FIG. 3 is an explanatory view showing a cross section of the ship 10. Here, the case where ballast water is made from seawater in a harbor is illustrated.

  As shown in FIG. 3, in the ship 10 according to the present embodiment, the ballast water sucked by the ballast pump 4 from the seawater suction box 2 is processed by the ballast water treatment system 1 and then stored in the ballast tank 3, or The ballast water stored in the ballast tank 3 is discharged from the seawater discharge port 5. The ballast water treatment system 1 includes a filter 6, an ozone injection device 7, a chemical injection pump 8, a main line, a sub line, instrumentation / control devices, and the like as shown in FIG. 1, for example.

  The filter 6 is provided in the main line and removes all L-sized organisms from the seawater sucked by the ballast pump 4. Here, a so-called disk type filter is used in which a plurality of filter elements are arranged around the rotation axis, and at least one of the filter elements is sequentially rotated around the rotation. Automatic reverse tip is possible, and ozone bubble water (water in which ozone is injected in the form of microbubbles: details are described later) is injected intermittently to prevent scale adhesion and biofilm formation. .

  The ozone injector 7 includes an oxygen / nitrogen generator 72, an ozone generator 73, and a nitrogen tank 74 incorporated in a casing 71, an ozone ejector 75, an ozone injection pump 76, a nitrogen ejector 77, and a nitrogen injector outside the casing 71. And a pump 78.

  The oxygen / nitrogen generator 72 generates oxygen as a raw material for ozone from air using, for example, an adsorbent, and supplies nitrogen simultaneously. The ozone generator 73 generates ozone from oxygen obtained by the oxygen / nitrogen generator 72 using, for example, silent discharge.

  The ozone ejector 75 is for making ozone into microbubbles, and the ozone injection pump 76 is for injecting ozone that has been microbubbled by the ozone ejector 75 to further reduce the bubble diameter and inject it into the main line. is there. Thereby, while being able to supply ozone stably, the living thing and bacteria of S size in seawater which pass the filter 6 with this ozone can be killed effectively.

  The nitrogen ejector 77 is for making nitrogen into microbubbles, and the nitrogen injection pump 78 is for injecting nitrogen that has been microbubbled with the nitrogen ejector 77 to further reduce the bubble diameter and inject it into the main line. is there. This nitrogen prevents an increase in dissolved oxygen (DO) concentration and suppresses the reproduction of living organisms.

  The chemical injection pump 8 injects sodium thiosulfate, which is a neutralizing agent, to decompose residual ozone and residual oxidant (TRO) as necessary. The concentration of residual ozone and residual oxidant is monitored to determine the amount of neutralizing agent to be injected, and TRO sensors are installed at appropriate locations on the main line in order to confirm the decomposition of residual ozone and residual oxidant in the ballast drainage. ing.

  Hereinafter, the schematic operation of the ballast water treatment system 1 will be described. In a series of operations, a control panel (not shown) receives a signal from a switch, a sensor, or the like so as to start / stop devices or open / close valves.

  At the time of ballasting, the water taken from the seawater suction box 2 by the ballast pump 4 is first filtered by the filter 6 to remove all L-sized organisms. Next, oxygen and nitrogen are generated from the air by the oxygen / nitrogen generator 72. The ozone generator 73 generates ozone using this oxygen as a raw material. Nitrogen is stored in a nitrogen tank 74.

  The ozone generated by the ozone generator 73 is converted into microbubbles (fine bubbles) by the ozone ejector 75. The microbubbled ozone is agitated by the ozone injection pump 76 to further reduce the bubble diameter, and is injected into the filtered water branched from the main line.

  Nitrogen stored in the nitrogen tank 74 is microbubbled by the nitrogen ejector 77. The microbubbled nitrogen is stirred by the nitrogen injection pump 78 to further reduce the bubble diameter and injected into the filtered water branched from the main line.

  This treated water is stored in the ballast tank 3. A part of the bubble ozone water is circulated, for example, on the upstream side of the filter 6 to prevent the scale 6 from adhering to the filter 6 and biofilm formation. In particular, once a biofilm is formed, it is troublesome because it cannot be removed by backwashing. Therefore, it is preferable that the ozone bubble water be circulated intermittently even during long-term voyage after the end of ballasting.

  On the other hand, at the time of deballasting, residual oxidant in the water drained by the ballast pump 4 and gravity is monitored by a TRO sensor. And as needed, sodium thiosulfate which is a neutralizing agent is added, controlling the injection amount. Finally, monitor the residual oxidant in the wastewater to confirm that it can be discharged. The main reasons are as follows.

  That is, not only ozone but also aquatic organisms in the ballast water are killed not only by the sterilizing action of residual oxidant produced by the reaction between ozone and seawater. Of these, ozone has a short half-life and decomposes quickly, so there is little impact on the environment. However, residual oxidants are difficult to decompose, so there is a problem in discharging them as they are from the ballast tank.

Therefore, the present inventors manufactured and tested a demonstration test system for the purpose of performance evaluation of the above-described ship ballast water treatment system 1, investigation of active substance dynamics, and determination of optimum parameters. The configuration of this demonstration test system corresponds to a configuration in which the seawater suction box 2 and the ballast tank 3 in FIG. 1 are replaced with two tanks. Table 2 shows the results of measuring the ozone concentration change in the tank simulating the ballast tank in this demonstration test system. Table 2 shows values obtained by measuring changes in the residual oxidant concentration over time for the set oxygen amount, nitrogen amount, and ozone concentration (theoretical value).

  The numerical value surrounded by the thick solid line in Table 2 is the case where the dissolved ozone concentration is confirmed to be 0.02 mg / l or more. Moreover, the numerical value enclosed with the thick broken line in Table 2 is a gas-phase ozone concentration detected, and includes the numerical value enclosed with the said thick solid line. As shown in Table 2, the residual oxidant concentration (measured value) was 0.00 mg / l in the original seawater, but immediately after the treatment, it was 1.12 to 2.18 mg / l, 120 minutes. It can be seen that there is a significant decrease after passing.

Next, Table 3 shows the results of measuring the concentration change of oxygen dissolved in the tank. Table 3 shows values obtained by measuring changes in dissolved oxygen concentration over time for the set oxygen amount, nitrogen amount, and ozone concentration (theoretical value).

  The numerical value enclosed with the thick broken line in Table 3 is a case where there is an increase of 3.0 ° C. or more from the original seawater temperature. As shown in Table 3, the dissolved oxygen concentration (measured value) from 9.81 to 12.12 mg / l in the original seawater is 10.80 to 23.74 mg / l immediately after the treatment. Considering the subsequent rise in seawater temperature, it can be seen that there is almost no decrease even after 4 days.

  By the way, if the dissolved oxygen concentration in the ballast water is increased, organisms may propagate in the ballast tank, which may cause a new problem. Therefore, the present inventor is conducting a verification test on whether or not the dissolved oxygen concentration can be controlled by further injecting nitrogen in this verification test system.

The results of measuring the dissolved oxygen concentration controlled by nitrogen injection are shown in Table 4. Table 4 shows values obtained by measuring the original seawater temperature, the dissolved oxygen concentration of the original seawater and the sample, and the sample temperature for the set oxygen amount and nitrogen amount, respectively.

  As shown in Table 4, the increase in the dissolved oxygen ratio is large when nitrogen is not injected, but the increase in the dissolved oxygen ratio is suppressed when nitrogen is injected.

  Next, the seawater treated with the filter 6 and the ozone injection device 7 was observed with a microscope, and the killing effect of the organism was verified. FIG. 4 shows before and after treatment of an L-size organism, and FIG. 5 shows before and after treatment of an S-size organism. 4 and 5, it was verified that an excellent killing effect was obtained in any size organism.

  As described above, according to the ballast water treatment system 1, relatively large microorganisms (L-size organisms) are completely removed from the water taken in the port of the ship 10 through the filter 6. Ozone is injected into the water that has been removed and filtered by the filter 6 in the form of fine bubbles by the ozone injection device 7, so that relatively small microorganisms (S-size organisms) and bacteria are killed from the water.

  In addition, ozone can be used not only for seawater but also for all kinds of water including fresh water and brackish water, and since it can be produced using air as a raw material on board and has high decomposability, there is little risk of residual. In addition, when seawater is used, it is possible to prevent the propagation of organisms in the ballast tank by the oxidant generated by the reaction between ozone and the seawater.

  In addition, ozone can be made into microbubbles to increase solubility and increase efficiency, and the amount of ozone used can be reduced.

  In this way, by improving the performance of the filter 6 and reducing the size of the ozone bubble in the ozone injection device 7, the system can meet not only the IMO standards but also the stricter standards that can be expected in the future. Was able to build.

  In the ozone injection device 7, ozone generated by the oxygen / nitrogen generator 72 is converted into microbubbles by the ozone ejector 75 and efficiently injected into the water filtered by the filter 6. The injected microbubbles in the water are stirred when sucked by the ozone injection pump 76 and become finer, so that stable microbubbles can be generated.

  Further, since the water sucked by the ozone injection pump 76 is injected into the filter 6, it is possible to prevent the formation of a biofilm on the filter 6 and to reduce clogging due to scale adhesion. Moreover, since nitrogen is injected in the form of fine bubbles in addition to the ozone, an increase in the ratio of dissolved oxygen can be suppressed.

(Embodiment 2)
By the way, in the said Embodiment 1, it isolate | separates into oxygen and nitrogen from air with the ozone generator 73, and ozone is generated using the oxygen as a raw material. However, when there is a large amount of ballast water, the amount of ozone used is enormous, which increases the size of the device and enormously consumes power, making it particularly difficult to install on existing ships. It becomes.

  On the other hand, not all ozone injected into water by the ozone injection device 7 is dissolved, and it is economical to recover and use the insoluble matter. However, if the recovered ozone is used as it is, there is a problem that a difference in concentration, a difference in humidity, or the like occurs with respect to the ozone generated by the ozone generator 73.

  Therefore, the present inventors further devised and constructed the ballast water treatment system 1a according to the second embodiment. FIG. 2 is an overall configuration diagram of a ship ballast water treatment system 1a according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the element which is common in the said Embodiment 1, and the detailed description is abbreviate | omitted.

  As shown in FIG. 3, in the ship 10 according to the second embodiment, the ballast water sucked by the ballast pump 4 from the seawater suction box 2 is treated by the ballast water treatment system 1a and then stored in the ballast tank 3. Alternatively, the ballast water stored in the ballast tank 3 is discharged from the seawater discharge port 5. The ballast water treatment system 1a includes, for example, as shown in FIG. 2, a filter 6, an ozone injection device 7, a chemical injection pump 8, an oxygen recovery device 9, a main line, a sub line, instrumentation / control devices, and the like. It has.

  The oxygen recovery device 9 includes an ozone deaeration tank 91, a compressor 92, and an ozone decomposition device 93. The ozone deaeration tank 91 is for recovering the ozone-containing gas present in the gas phase without being dissolved, and the compressor 92 is for supplying the recovered ozone-containing gas to the ozone decomposing device 93. No. 93 generates oxygen by decomposing ozone in the supplied ozone-containing gas using, for example, a manganese dioxide-based catalyst. Oxygen generated by the ozonolysis device 93 is supplied to the ozone generator 73, and ozone is also generated from this oxygen.

  Hereinafter, a schematic operation of the ballast water treatment system 1a will be described. In a series of operations, a control panel (not shown) receives a signal from a switch, a sensor, or the like so as to start / stop devices or open / close valves.

  At the time of ballasting, the water taken from the seawater suction box 2 by the ballast pump 4 is first filtered by the filter 6 to remove all L-sized organisms. Next, oxygen and nitrogen are generated from the air by the oxygen / nitrogen generator 72. The ozone generator 73 generates ozone using this oxygen as a raw material. Nitrogen is stored in a nitrogen tank 74.

  The ozone generated by the ozone generator 73 is converted into microbubbles (fine bubbles) by the ozone ejector 75. The microbubbled ozone is agitated by the ozone injection pump 76 to further reduce the bubble diameter, and is injected into the filtered water branched from the main line. The ozone-containing body in the gas phase is recovered by the ozone degassing tank 91.

  Nitrogen stored in the nitrogen tank 74 is microbubbled by the nitrogen ejector 77. The microbubbled nitrogen is stirred by the nitrogen injection pump 78 to further reduce the bubble diameter and injected into the filtered water branched from the main line.

  This treated water is stored in the ballast tank 3. A part of the bubble ozone water is circulated, for example, on the upstream side of the filter 6 to prevent the filter 6 from adhering to the scale or forming a biofilm. The ozone-containing gas recovered by the degassing tank is treated to decompose ozone and obtain oxygen. This oxygen is sent to the ozone generator 73.

  On the other hand, at the time of deballasting, residual oxidant in the water drained by the ballast pump 4 and gravity is monitored by a TRO sensor. And as needed, sodium thiosulfate which is a neutralizing agent is added, controlling the injection amount. Finally, monitor the residual oxidant in the wastewater to confirm that it can be discharged. The main reason is as described above.

  As described above, according to the ballast water treatment system 1a, in addition to the operational effects of the ballast water treatment system 1 of the first embodiment, oxygen that recovers oxygen that has not dissolved in the water from the water into which ozone is injected. Since the recovery device 9 is provided and the oxygen recovered by the oxygen recovery device 9 is returned to the ozone generator 73 of the ozone injection device 7, the system can be made compact and the power consumption can be reduced.

  In the first and second embodiments, ballast water is produced by treating seawater. However, ballast water treatment may be produced by treating fresh water, brackish water, or the like.

  In the first and second embodiments, an existing ballast line is used as the main line so that it can be applied to a modified ship. However, in the case of a new ship, there is no such limitation. Needless to say.

  In the first and second embodiments, one ballast tank 3 of the ship 10 is illustrated, but it goes without saying that a plurality of ballast tanks 3 are actually provided.

  In the first and second embodiments, one filter 6 is illustrated. However, a plurality of filters 6 may be provided to enable switching between them.

DESCRIPTION OF SYMBOLS 1,1a Ship ballast water treatment system 10 Ship 2 Seawater intake box 3 Ballast tank 4 Ballast pump 5 Seawater outlet 6 Filter 7 Ozone injection device 71 Case 72 Oxygen / nitrogen generator 73 Ozone generator 74 Nitrogen tank 75 Ozone ejector 76 Ozone injection pump 77 Nitrogen ejector 78 Nitrogen injection pump 8 Chemical injection pump 9 Oxygen recovery device 91 Ozone deaeration tank 92 Compressor 93 Ozone decomposition device

JP 2010-42331 A

Claims (5)

A ship ballast water treatment system for producing ballast water by removing microorganisms and bacteria from water taken at a port of call of a ship,
A filter capable of removing relatively large microorganisms from the water by filtering the water taken at the port of call of the ship;
A ship ballast water treatment system comprising an ozone injection device capable of removing relatively small microorganisms and bacteria from water by injecting ozone into the water filtered by the filter in the form of fine bubbles. .   The said ozone injection | pouring apparatus was equipped with the ejector which inject | pours ozone into the water filtered with the filter element of the said filter apparatus, and the pump which attracts | sucks the water by which ozone was inject | poured by the ejector. Ship ballast water treatment system.   3. The ship ballast water treatment system according to claim 2, wherein the filter is back-washed with at least part of the water sucked by the pump.   The ship ballast water treatment system according to any one of claims 1 to 3, wherein nitrogen is further injected into the water filtered by the filter in the form of fine bubbles.   An oxygen recovery device is provided for recovering oxygen by decomposing ozone not dissolved in the water into which the ozone has been injected, and the oxygen recovered by the oxygen recovery device is reused as a raw material for ozone injected by the ozone injection device. The ship ballast water treatment system according to any one of claims 1 to 5, which is used.