JP2017124359A - Processing method and processing system of contaminated muddy water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method and system of contaminated muddy water that has a simple apparatus structure and is easy to deal with large throughput compared with conventional magnetic separation or centrifugal separation.SOLUTION: A processing method of contaminated muddy water includes a step S06 for mixing object contaminated muddy water with iron powder, a step S07 for separating the iron powder from the muddy water mixed with the iron powder by gravity separation, and a step S08 for recovering the separated iron powder. The muddy water mixed with the iron powder is transported to a gravity separation unit having a large cross-section area through a water pipe having a small cross-section area. The iron powder precipitates from the muddy water mixed with the iron powder in the gravity separation unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a processing method and a processing system for contaminated mud water and the like.

  The muddy water and dredged soil generated during excavation work by the shield method may contain naturally derived arsenic or heavy metals. As countermeasures against such problems, iron powder is added to drilling mud that contains arsenic and exceeds the soil environmental standards, and after adsorbing arsenic on the iron powder surface, iron powder is separated and recovered by centrifugation or magnetic separation, Methods and systems for obtaining non-contaminated soil have been proposed (see, for example, Patent Documents 1, 2, and 3).

JP 2011-56482 A JP 2014-73464 A JP 2014-188408 A

  According to Patent Documents 1 to 3, in addition to the conventional muddy water treatment facility, a complicated magnetic separation device and a centrifugal separation device for collecting iron powder are necessary, and it is inevitable that the processing cost increases. Further, when a large amount of muddy water is processed by magnetic separation or centrifugation, the number of devices installed increases because the processing capacity of each device is small. In addition, since the mechanism of magnetic separation and centrifugation is complicated, there is a large scale disadvantage in terms of cost when the target scale increases. In addition, when the mud containing iron powder is centrifuged, it is predicted that the wear of the apparatus will increase.

  In view of the above-described problems of the prior art, the present invention provides a method and system for treating contaminated mud water that has a simpler device structure than conventional magnetic separation and centrifugal separation and can easily cope with an increase in the amount of treatment. The purpose is to provide.

  The method for treating contaminated mud water for achieving the above-mentioned object includes a step of mixing iron powder into the contaminated mud water to be treated, a step of separating the iron powder by specific gravity separation from the iron powder mixed mud water, and the separated A step of recovering iron powder, and passing the iron powder mixed mud water through a water pipe having a small water cross section to a specific gravity separation section having a large water cross section, and from the iron powder mixed mud water in the specific gravity separation section The specific gravity separation is performed by allowing the iron powder to settle.

  According to this method for treating contaminated mud water, iron powder is mixed with the contaminated mud water to be treated so that the arsenic and heavy metals to be treated contained in the mud water are adsorbed to the iron powder, and this iron powder mixed mud water is passed through. When sent to a specific gravity separation section with a large water flow cross section through a water pipe with a small water cross section, the flow rate of iron powder mixed mud decreases in the specific gravity separation section, and iron powder with a large specific gravity is faster than soil particles with a small specific gravity. By settling at the settling speed, the iron powder and the soil particles can be separated by specific gravity. By separating and recovering the iron powder adsorbing arsenic and heavy metals in this way, the contaminated mud can be treated into non-contaminated mud. The specific gravity separation unit has a simpler device structure than conventional magnetic separation and centrifugal separation, and can be processed in large quantities simply by increasing the volume of the specific gravity separation unit. Can be easily handled.

  In the method for treating contaminated mud water, when the muddy water after the specific gravity separation is discharged from the specific gravity separation section through the drain pipe, a magnet disposed on the upstream side of the drain pipe or on the downstream side of the specific gravity separation section. It is preferable to separate the iron powder from the muddy water after the specific gravity separation. Iron powder with relatively small particles is often contained in muddy water after separation of specific gravity, but can be easily separated and removed by a magnet. Since the magnet is only disposed on the upstream side of the drain pipe and the downstream side of the specific gravity separation unit, the structure of the apparatus is not complicated.

  Moreover, it is preferable to generate an upward flow in the specific gravity separation part. Thereby, it can reduce that soil particles mix in the separated iron powder. The upflow velocity (absolute value) at this time is larger than the sedimentation rate of the soil particles and smaller than the sedimentation rate of the iron powder, thereby improving the mixing reduction effect.

  Moreover, it is preferable that the average particle diameter of the said iron powder is 70-300 micrometers. The iron powder is preferably mixed in an amount of 1 to 50% by weight with respect to the soil particles.

  The recovered iron powder is preferably reused in the iron powder mixing step as it is or after being regenerated. In addition, it is preferable to remove gravel and sand from the contaminated mud before the iron powder mixing step.

  The treatment system for contaminated mud water for achieving the above object includes an iron powder mixing unit for mixing iron powder into the contaminated mud water to be treated, and a specific gravity separation unit for separating the iron powder from the iron powder mixed mud water by specific gravity separation. Recovery means for recovering the separated iron powder, and passing the iron powder mixed mud water to the specific gravity separation section having a large water cross section through a water supply pipe having a small water cross section, and the specific gravity separation section The specific gravity separation is performed by allowing the iron powder to settle from the iron powder mixed mud.

  According to this treatment system for contaminated mud water, iron powder is mixed with the contaminated mud water to be treated to adsorb the arsenic and heavy metals to be treated contained in the mud water to the iron powder, and this iron powder mixed mud water is passed through. When sent to a specific gravity separation section with a large water flow cross section through a water pipe with a small water cross section, the flow rate of iron powder mixed mud decreases in the specific gravity separation section, and iron powder with a large specific gravity is faster than soil particles with a small specific gravity. By settling at the settling speed, the iron powder and the soil particles can be separated. By separating and recovering the iron powder that adsorbs arsenic and heavy metals in this way, the contaminated mud can be processed into non-contaminated mud. The specific gravity separation unit has a simpler device structure than conventional magnetic separation and centrifugal separation, and can be processed in large quantities simply by increasing the volume of the specific gravity separation unit. Can be easily handled.

  In the treatment system for contaminated mud water, when discharging the muddy water after the specific gravity separation from the specific gravity separation part through the drain pipe, a magnet is arranged on the upstream side of the drain pipe or on the downstream side of the specific gravity separation part, The iron powder is preferably separated from the muddy water after the specific gravity separation by the magnet. Iron powder with relatively small particles is often contained in muddy water after separation of specific gravity, but can be easily separated and removed by a magnet. Since the magnet is only disposed on the upstream side of the drain pipe and the downstream side of the specific gravity separation unit, the structure of the apparatus is not complicated.

  It is preferable that the specific gravity separation unit includes an upflow generation unit that generates an upflow. Thereby, it can reduce that soil particles mix in the separated iron powder. The upflow velocity (absolute value) at this time is larger than the sedimentation rate of the soil particles and smaller than the sedimentation rate of the iron powder, thereby improving the mixing reduction effect. In addition, it is preferable to arrange a gravel / sand removal part for removing gravel / sand from the contaminated mud water upstream of the iron powder mixing part.

  ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional magnetic separation and centrifugation, an apparatus structure can be simplified and the processing method and system of contaminated mud water which can respond easily to the increase in a processing amount can be provided.

It is a flowchart for demonstrating each process of the processing method of the contaminated mud water by this embodiment. It is the side view (a) and top view (b) which show schematically the processing system of the contaminated mud water which can perform the processing method of the contaminated mud water of FIG. It is side view (a)-(g) which shows roughly the specific gravity separation apparatus applicable to the processing system of the contaminated mud water of FIG. It is a side view (a) (b) which shows roughly the specific gravity separation apparatus which has an upflow generation | occurrence | production part applicable to the processing system of the contaminated mud water of FIG. It is the top view (a), front view (b), and side view (c) which show the specific example of the specific gravity separator by this embodiment. 6 is a graph showing a dissolution test result in Experimental Example 1. 6 is a graph showing a dissolution test result in Experimental Example 2. It is figure (a) (b) which shows the experimental apparatus of Experimental example 3. FIG. It is a graph which shows the test result in Experimental example 3 (no magnet). It is a graph which shows the test result in Experimental example 3 (with a magnet). 10 is a graph showing test results in Experimental Example 4.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining each step of the contaminated mud treatment method according to this embodiment. FIG. 2 is a side view (a) and a top view (b) schematically showing a contaminated mud water treatment system 10 capable of executing the contaminated mud water treatment method of FIG. 1.

  The steps S01 to S10 of the contaminated mud treatment method according to the present embodiment will be described with reference to FIGS. 1, 2A, and 2B. First, when contaminated mud is generated in the excavation process by the shield machine (S01). , Send the contaminated mud water to a gravel removal device (not shown) consisting of a vibrating screen, remove the gravel with a diameter of 2mm or more from the contaminated mud water (S02), and further remove the gravel with a cyclone equipped screen (not shown) Sand having a diameter of 75 μm or more is removed (S03). Of the removed gravel and sand, those whose elution amount is below the soil environmental standard are disposed of as non-contaminated soil (S04).

  The muddy water from which the gravel and sand are removed is once stored in the mud tank 11 (S05). The muddy water necessary for the excavation process by the shield machine may be sent from the mud tank 11.

  Next, the muddy water after the removal of the gravel from the mud conditioning tank 11 is sent to the agitation / reaction tank 12, iron powder is added to the muddy water, and the mixture is stirred and mixed in the agitation / reaction tank 12 to be contained in the muddy water. Arsenic and heavy metals to be adsorbed on iron powder (S06). As shown in FIGS. 2A and 2B, the iron powder FIBC FE is quantified and cut into the feeder FD by the crane CR, and a certain amount of iron powder is supplied to the agitation / reaction tank 12.

  It is preferable to use iron powder having an average particle size of 70 to 300 μm as an adsorbent for arsenic and heavy metals. The mixing amount of the iron powder is preferably 1 to 50% by weight with respect to the soil particles. In addition, it is preferable to use iron powder having a high arsenic adsorption capacity. For example, heavy metal contaminated soil and groundwater purification iron powder "Ecomel" (registered trademark) sold by Kobe Steel, Ltd. can be used. .

  Next, as shown in FIGS. 2 (a) and 2 (b), the iron powder mixed mud is separated from the agitation / reaction tank 12 by the specific gravity separation device 17 while adjusting the flow rate from the agitation / reaction tank 12 with the pressure pump 13. It supplies to the tank 17a. In the middle of the supply, the flow rate and density of the iron powder mixed mud water are measured by the flow meter 14 and the density meter 15, and the supply amount and iron powder mixed amount of the iron powder mixed mud water are managed.

  The specific gravity separation device 17 includes a specific gravity separation tank 17a having a cross section larger than the pipe diameter of the upstream water supply pipe 16, and a rising portion 17b that communicates with the specific gravity separation tank 17a and is provided substantially vertically on the downstream side. And a drain pipe 20 connected horizontally to the upper end of the rising portion 17b, and a magnet 19 disposed at a corner of the rising portion 17b. In the specific gravity separation device 17, the muddy water flows from the water supply pipe 16 to the upper end on the upstream side of the specific gravity separation tank 27 a, and since the rising portion 17 b is provided, it flows out from the drain pipe 20 at a position higher than the water supply pipe 16. .

Iron powder is separated from the iron powder mixed mud water by specific gravity separation in the specific gravity separation tank 17a of the specific gravity separator 17 (S07). That is, when the iron powder mixed mud flows into the specific gravity separation tank 17a having a cross section larger than the diameter of the water pipe 16, the flow velocity is greatly reduced, and iron powder (density 7.87 g / cm ³ ) and soil particles (density) Due to the difference in specific gravity from about 2.66 g / cm ³ ), the iron powder is separated by settling iron powder with a high settling speed.

  The muddy water from which the iron powder has been separated flows and is discharged from the specific gravity separation tank 17a through the drain pipe 20, but since this muddy water contains relatively small particles of iron powder, the iron powder is separated from the specific gravity separation tank 17a. Is removed by a magnet 19 installed on the upstream side of the drainage pipe on the discharge side (downstream side) (magnetic separation). By installing the magnet 19 in this way, even when the amount of muddy water is increased and the flow rate is increased, iron powder of relatively small particles adsorbed with arsenic or the like can be efficiently recovered.

  Next, the iron powder FE separated from the iron powder mixed muddy water is scraped out from the specific gravity separation tank 17a using the backhoe BH or the like and moved to the recovered iron powder tank 22 to be recovered (S08).

  By separating and collecting iron powder from the iron powder mixed mud as described above, non-contaminated mud is obtained. The mud is discharged through the drain pipe 20 and once stored in the muddy water tank 21, and then dehydrated. -It is sent to a turbid water treatment facility (not shown) (S09), dehydrated, moisture is discharged, and clay content whose elution amount is below the soil environmental standard is disposed as non-contaminated sludge (S10).

  According to the method and system for treating contaminated mud water of the present embodiment, after removing the gravel and sand from the contaminated mud water to be treated, iron powder is mixed into the contaminated mud water so that the treatment target contained in the mud water can be treated. When arsenic and heavy metals are adsorbed on iron powder, and this iron powder mixed mud is sent to a specific gravity separation tank with a large cross section through a water pipe with a small cross section, the flow velocity of the iron powder mixed mud in the specific gravity separation tank Decreases, and iron powder having a large specific gravity settles at a faster settling speed than soil particles having a small specific gravity, whereby the iron powder and the soil particles can be separated by specific gravity. By separating and recovering the iron powder that has adsorbed heavy metals in this manner, the contaminated mud can be processed into non-contaminated mud.

  Next, another example of the specific gravity separator in FIG. 2 will be described with reference to FIG. FIG. 3 is a side view (a) to (h) schematically showing a specific gravity separator applicable to the contaminated mud treatment system of FIG.

  In the specific gravity separation device of FIG. 3A, muddy water flows in from the water supply pipe 16 located at the upper end of the specific gravity separation tank 27 a and flows out from the drain pipe 20 at the same height as the water supply pipe 16. The sedimentation of the iron powder FE occurs preferentially mainly in the vicinity of the upstream to the center on the water pipe 16 side in the specific gravity separation tank 27a. In addition, also in the specific gravity separation tank 17a of FIGS.

  In the specific gravity separation device of FIG. 3B, muddy water flows in from the water supply pipe 16 located at the lower end of the specific gravity separation tank 27b and flows out from the drain pipe 20 located at the upper end of the specific gravity separation tank 27b.

  In the specific gravity separation device of FIG. 3 (c), muddy water flows from the water pipe 16 extending vertically into the tank from the bottom plate of the specific gravity separation tank 27c, and flows out from the drain pipe 20 located at the upper end of the specific gravity separation tank 27c. It has become. The sedimentation of the iron powder FE occurs almost evenly in the specific gravity separation tank 2cb.

  3 (d) to 3 (f) has a flat plate on the upper horizontal portion (downstream of the specific gravity separation tank) of the specific gravity separation tanks 27a to 27c in addition to the magnet 19 arranged on the upstream side of the drain pipe 20. The magnet 25 is arranged. The magnets 19 and 25 are made to adsorb relatively small particles of iron powder FE 'so that they can be efficiently removed and recovered.

  The specific gravity separation device in FIG. 3G is a device in which a plate-like magnet 25 is disposed on the upper horizontal portion (downstream of the specific gravity separation tank) of the rising portion 17b above the specific gravity separation tank 17a in FIG. The magnets 19 and 25 are made to adsorb relatively small particles of iron powder FE 'so that they can be efficiently removed and recovered.

  The specific gravity separation device of FIG. 3 (h) is configured such that muddy water flows in the specific gravity separation tank 27d from the water supply pipe 16 positioned at the lower end and flows out from the drain pipe 20 positioned at the upper end of the rising portion 27e. In addition, a plate-like magnet 25 is disposed on the upper horizontal portion (downstream of the specific gravity separation tank) of the rising portion 27e. The magnets 19 and 25 are made to adsorb relatively small particles of iron powder FE 'so that they can be efficiently removed and recovered.

  The specific gravity separators of FIGS. 2 and 3 (a) to 3 (g) have a simpler device structure than conventional magnetic separation and centrifugal separation, and can be processed in large quantities simply by increasing the volume of the specific gravity separation tank. Therefore, it is possible to easily cope with an increase in the amount of contaminated mud. 2 and 3 (a) to 3 (g), the magnets 19 and 25 are installed outside the apparatus, but may be installed inside the apparatus. Moreover, a permanent magnet, an electromagnet, etc. can be used for a magnet.

  Next, still another example of the specific gravity separation device of FIG. 2 will be described with reference to FIG. FIGS. 4A and 4B are side views (a) and (b) schematically showing a specific gravity separator having an upflow generation unit applicable to the contaminated mud water treatment system of FIG.

  4 (a) and 4 (b), the specific gravity separation device generates an upward flow from their bottom surfaces in the specific gravity separation tank 27a of FIG. 3 (a) and the specific gravity separation tank 27c of FIG. 3 (c). Is provided. As such an upflow generation part, for example, a water flow can be raised from a perforated steel pipe arranged in the bottom plate by an external pump or the like. By generating the upward flow from the bottom of the tank, it is possible to reduce the mixing of soil particles into the separated iron powder. The upflow velocity (absolute value) at this time is larger than the sedimentation rate of the soil particles and smaller than the sedimentation rate of the iron powder, thereby improving the mixing reduction effect.

  The iron powder after the recovery in the iron powder recovery step S08 in FIG. 1 is reused as it is when the processing capacity for arsenic or the like remains, and when the capacity does not remain, it can be regenerated by washing with acid or the like. Dispose off-site.

  Judgment of arsenic adsorption capacity of iron powder is based on a method in which the adsorption capacity of iron powder is determined in advance and calculated from the arsenic concentration in the muddy water before treatment. For example, a method for confirming the remaining power by analyzing the concentration of iron, and a method for analyzing the arsenic concentration on the surface of the iron powder.

  Also, the iron powder after separation is recovered by stopping the specific gravity separator (for example, scraped and recovered using a backhoe BH as shown in FIGS. 2 (a) and 2 (b)) and discharged to the specific gravity separator. It can be recovered by a method of continuously collecting iron powder by installing an apparatus, a method of preparing a plurality of specific gravity separators and using them alternately, and scraping out the iron powder that is not used.

  5A to 5C show specific examples of the specific gravity separation device according to the present embodiment. The specific gravity separation device 30 of FIGS. 5A to 5C embodies the specific gravity separation device of FIGS. 2A and 2B, and includes a specific gravity separation tank 31, a rising portion 32, and a plurality of tank stands. 33. The specific gravity separation tank 31 is an iron powder mixed mud water injection port 31a arranged at the upper side of the side surface of FIG. 3 (c), an openable / closable rectangular lid 34 arranged on the horizontal upper surface of the tank, and the inside of the tank for inspection. And a viewing window 36 for peeking. The rising portion 32 has a muddy water discharge port 32a provided on the upper surface thereof and a plurality of magnet insertion holes 35 provided on the upper side surface. A rod-shaped magnet 37 is inserted into the magnet insertion hole 35 as indicated by a broken line in FIG. 5A, and the magnet 37 is positioned horizontally near the inner upper surface of the rising portion 32.

  According to the specific gravity separation device 30 of FIGS. 5A to 5C, when the iron powder mixed mud flows into the specific gravity separation tank 31 from the inlet 31a, the iron powder settles due to the specific gravity separation, and the rising portion 32 Relatively small particles of iron powder are adsorbed to a plurality of rod-shaped magnets 37 arranged in the vicinity of the inner upper surface (downstream of the specific gravity separation tank). The iron powder adsorbed on the rod-shaped magnet 37 can be easily removed by dropping around the hole 35 when the magnet 37 is pulled out from the magnet insertion hole 35.

  According to the contaminated muddy water treatment system of the present embodiment, the structure of the device is simple compared to magnetic separation and centrifugal separation, and when it is desired to increase the amount of treatment, both the increase in the size of the device and the increase in the number of devices can be handled. It is possible, and a large amount of contaminated mud can be treated with a simple and low-cost system.

  Moreover, the collection | recovery condition of iron powder can be adjusted by setting the flow rate of iron powder mixed mud in the specific gravity separator, the addition to mud (adjustment of viscosity), and the like. For example, it is possible to increase the sedimentation ratio of the iron powder in the specific gravity separation tank by reducing the viscosity by adding water to the iron powder mixed mud water.

Experimental example

  Hereinafter, the effects of the present embodiment were confirmed by Experimental Examples 1 to 4. Experimental example 1 confirms the influence which the particle size of iron powder has on the adsorptivity of iron powder. Increasing the particle size of iron powder reduces the surface area per unit weight and decreases the contact and reaction efficiency with arsenic and heavy metals, but adjusts the removal capacity of heavy metals by increasing the amount of iron powder added and adjusting the reaction time can do.

  FIG. 6 shows the results of adding and mixing iron powders having different particle diameters to bentonite mud containing arsenic and conducting an elution test after iron powder recovery. As can be seen from Fig. 6, the arsenic elution amount in the case of 10% iron powder with a median particle size of 150μm (weight ratio to bentonite soil particles) is the same as the case of 10% iron powder with a median particle size of 70μm. Fell below the soil environmental standards. In the case of iron powder with a median particle size of 300 μm, the soil environmental standard was exceeded in the case of mixing 10% and 30%, but was below the soil environmental standard in the case of mixing 50%. It can be seen that when the particle size of the iron powder is relatively small, the adsorptivity to arsenic and heavy metals is good and the ability to remove arsenic and heavy metals is excellent. It can also be seen that even if the particle size of the iron powder is relatively large, the removal ability of arsenic and heavy metals can be adjusted by increasing the iron powder mixing amount.

  Next, the influence of the reaction time on the iron powder adsorptivity was investigated in Experimental Example 2. FIG. 7 shows the result of conducting an elution test by adding iron powder having a median particle diameter of 72 μm to the clay and mixing it, removing the iron powder after a predetermined time has elapsed. As can be seen from Fig. 7, when the mixing amount of iron powder is 1%, 5%, and 10%, the soil environmental standard is below the point when 10 minutes have passed, but the reaction time is 30 minutes. In the case of 1% addition, a decrease in elution amount was observed. That is, it can be seen that when the contamination concentration is low, the amount of iron powder added can be reduced, and the amount of iron powder added can be reduced by increasing the reaction time.

  Next, the effect of the rising flow velocity when muddy water was introduced and raised from the bottom of the specific gravity separation tank as shown in FIG. FIG. 8A shows an experimental apparatus composed of a cylindrical column having a magnet disposed at the upper end (upstream end of the drain pipe), and FIG. 8B shows an experimental apparatus having the same configuration but omitting the magnet.

  Fig. 9 (No magnet), Fig. 9 shows the ascending flow rate, the settling rate of iron powder, and the outflow rate when the iron powder mixed mud is supplied and raised from the bottom of the cylindrical column shown in Figs. 8 (a) and 8 (b). 10 (with magnet). This settling rate and outflow rate are the weight ratio of the settling and outflowing iron powder to the mixed iron powder. The flow rate here is the flow rate in the cylindrical column, and is a value calculated from the amount of muddy water and the cross-sectional area. From FIG. 9, the amount of processing can be increased by increasing the ascending flow rate in the apparatus. However, when there is no magnet, the amount of iron powder flowing out increases, the amount of iron powder collected by the magnet decreases, and conversely the flow rate If the value is made smaller, the amount of spilled iron powder can be reduced although the processing amount is reduced. In addition, from FIG. 10, by arranging magnets, the amount of iron powder flowing out is only slightly reduced even if the ascending flow rate in the apparatus is increased to increase the processing amount, and the effect of magnet arrangement can be confirmed. It was.

  The experimental apparatus of FIG. 8A simulates the configuration of FIGS. 3C and 3F, and it can be said that the effect of the specific gravity separation apparatus of FIGS. 3C and 3F has been confirmed. 3B and 3E, it can be said that the separation state based on the flow velocity in the vertical direction could be confirmed by Experimental Example 3.

  Next, the influence of the viscosity of the iron powder mixed mud water was investigated according to Experimental Example 4 using the experimental apparatus shown in FIG. The viscosity is adjusted by adding water to the iron powder mixed mud water, and the settling rate and outflow rate of the iron powder when the rising flow rate is changed in three stages are examined, and the results are shown in FIG. From FIG. 11, by reducing the viscosity of the iron powder mixed mud water and reducing the value of the funnel viscosity, the sedimentation ratio of the iron powder is increased at any flow rate and the magnetic separation load is reduced (separation and recovery of the iron powder from the magnet). It can be seen that it is possible to reduce the frequency). The funnel viscosity of the iron powder mixed mud was measured using a funnel viscometer (S-251) manufactured by West Japan Testing Machine Co., Ltd.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the contaminated mud water to be treated in the present embodiment is generated in the excavation process by the shield machine. However, the present invention is not limited to this, and can naturally be applied to other contaminated mud water.

  Moreover, the specific gravity separator which isolate | separates specific gravity of iron powder is not limited to a tank structure, For example, a pipe line structure may be sufficient and the flow path which the upper part opened may be sufficient.

  Further, in FIG. 5, the iron powder adsorbed on the magnet is forcibly removed and collected by a mechanical configuration, but the invention is not limited to this. For example, the iron powder is collected by switching on and off using an electromagnet. You may do it. Moreover, the position of the magnet in Fig.2 (a) and FIG.3 (a)-(c) is not limited to the position shown in figure, For example, the drain pipe vicinity by the side of a specific gravity separation apparatus may be sufficient. Moreover, a magnet may be arrange | positioned in multiple positions like FIG.3 (d)-(h), and may be arrange | positioned in multiple positions by the side of a drain pipe.

  In addition, when dredged soil containing natural arsenic and heavy metals is used for landfill, the ground will exceed soil environmental standards after landfill is completed (if the landfill level is below the bottom sediment standard) By applying this method to dredged soil containing arsenic, etc., it is possible to make the ground below the soil environmental standard. When applying to dredged soil in this way, for example, iron powder can be recovered using the present method / system immediately before adding / mixing iron powder in a ship carrier and putting it into a landfill on a Virgin loader ship. it can.

  Also, if there is a lot of iron sand in the dredged soil and it is expected that it will be difficult to distinguish between the two when recovered with iron powder and reused, use this system as a pre-treatment with the first one After collecting iron sand, it is conceivable to add iron powder and collect iron powder at the second unit.

  According to the method and system for treating contaminated mud water of the present invention, the structure of the apparatus becomes simpler than conventional magnetic separation and centrifugal separation, and it is easy to cope with an increase in the amount of treatment. The contaminated mud can be treated.

10 Contaminated Mud Water Treatment System 12 Stirring / Reaction Tank 16 Water Pipe 17 Specific Gravity Separation Device 17a Specific Gravity Separation Tank (Specific Gravity Separation Section)
19, 25 Magnet 20 Drain pipes 27a to 27c Specific gravity separation tank (specific gravity separation part)
30 Specific gravity separator 31 Specific gravity separation tank (specific gravity separation unit)
35 Magnet insertion hole 37 Magnet FE, FE 'Iron powder

Claims (9)

Mixing iron powder into contaminated mud water to be treated;
Separating the iron powder by specific gravity separation from the iron powder mixed mud,
Recovering the separated iron powder, and
The iron powder mixed mud water is sent to a specific gravity separation section having a large water flow cross section through a water pipe having a small water cross section, and the specific gravity separation is performed by allowing the iron powder to settle from the iron powder mixed mud water in the specific gravity separation section. A method for treating contaminated mud water.   When discharging the muddy water after the specific gravity separation from the specific gravity separation part through the drain pipe, the magnet arranged on the upstream side of the drain pipe or the downstream side of the specific gravity separation part from the muddy water after the specific gravity separation. The method for treating contaminated mud water according to claim 1, wherein the iron powder is separated.   The method for treating contaminated mud according to claim 1 or 2, wherein an upward flow is generated in the specific gravity separation section.   The method for treating contaminated mud water according to any one of claims 1 to 3, wherein an average particle diameter of the iron powder is 70 to 300 µm.   The method for treating contaminated mud water according to any one of claims 1 to 4, wherein the iron powder is mixed by 1 to 50% by weight with respect to the soil particles.   The method for treating contaminated mud water according to any one of claims 1 to 5, wherein the recovered iron powder is reused in the iron powder mixing step as it is or after being regenerated. An iron powder mixing section for mixing iron powder into contaminated mud water to be treated;
A specific gravity separation part for separating the iron powder from the iron powder mixed mud by specific gravity separation;
Recovery means for recovering the separated iron powder,
The iron powder mixed mud is passed through a water pipe having a small water cross-sectional area and sent to the specific gravity separation part having a large water flow cross-sectional area, and the specific gravity is set by allowing the iron powder to settle from the iron powder mixed mud in the specific gravity separation part. A treatment system for contaminated mud water characterized by separation.   When discharging the muddy water after the specific gravity separation through the drainage pipe from the specific gravity separation part, a magnet is disposed on the upstream side of the drainage pipe or on the downstream side of the specific gravity separation part, and the magnet after the specific gravity separation by the magnet The processing system for contaminated mud water according to claim 7, wherein the iron powder is separated from the mud water.   The treatment system for contaminated mud water according to claim 7 or 8, further comprising an upflow generation unit that generates an upflow in the specific gravity separation unit.

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