JP5020397B1 - Water treatment system and water treatment method - Google Patents

Abstract

Provided are a water treatment apparatus and a water treatment method in which phosphorus removal efficiency is improved in removing phosphorus contained in water to be treated with a phosphorus removal filter medium containing slag.
In a water treatment system for removing phosphorus contained in water to be treated by bringing it into contact with a phosphorus removal filter medium, the phosphorus removal filter medium brought into contact with the water to be treated contains slag, and the average particle size is 0.1 mm or less. The slag is used. In this case, by selectively using the slag having the average particle diameter, the phosphorus removal filter medium exhibits high phosphorus removal performance. As a result, even if the emission standard value of phosphorus is lowered, it is possible to cope with it. It is.
[Selection] Figure 2

Description

  The present invention relates to a water treatment system and a water treatment method, and more particularly, to a water treatment system and a water treatment method for removing phosphorus contained in water to be treated by bringing it into contact with a phosphorus removal filter medium.

  For example, emission standard values such as sewage and wastewater are defined by the Emission Pollution Prevention Law and regulations. Emission standards tend to be more stringent for environmental protection, and phosphorus is one of the causes of eutrophication. Even if we look overseas, there is a tendency for the emission standards of phosphorus to be strengthened. For example, in South Korea, the total phosphorus (TP) concentration will be reduced to 0.2 mg / l.

  As a filter medium that exhibits phosphorus removal ability, for example, slag produced as a by-product in a steelworks or the like is known (for example, Patent Documents 1-4). However, in the conventional method, the removal efficiency is not sufficient, and there are cases where it cannot be performed when a strict emission reference value is set.

  Furthermore, in the conventional method, an alkaline solution is continuously added to the water to be treated in order to increase the phosphorus removal activity of the slag. It is desirable to omit such chemical addition to the water to be treated from the viewpoint of environmental protection. However, the conventional phosphorus removing filter medium cannot sufficiently remove phosphorus without adding an alkali.

Japanese Patent Laid-Open No. 2005-262044 JP 2006-341226 A Japanese Patent Laid-Open No. 11-57694 JP 2002-86139 A

  The present invention has been made based on such circumstances, and an object of the present invention is to provide a water treatment apparatus with improved phosphorus removal efficiency in removing phosphorus contained in water to be treated with a phosphorus removal filter medium containing slag. And providing a water treatment method.

  Another object of the present invention is to provide a water treatment apparatus and a water treatment method capable of stably removing phosphorus even if chemical solution addition to water to be treated is omitted.

The water treatment system of the present invention is a water treatment system for removing phosphorus contained in water to be treated by bringing it into contact with a phosphorus removal filter medium, wherein the phosphorus removal filter medium is a clay-based slag having an average particle diameter of 0.1 mm or less. The water treatment system is mixed with a binder, granulated into particles having an average particle diameter of 0.3 mm or less, and baked, and the water treatment system is a stirring tank for adding the phosphorus removal filter medium to the water to be treated and stirring the water. A filter medium addition device for adding a phosphorus removal filter medium to the agitation tank and a water to be treated containing the phosphorus removal filter medium discharged from the agitation tank are subjected to solid-liquid separation, and a phosphorus removal filter medium is removed from the process water from which phosphorus has been removed. A sedimentation separation tank or solid-liquid separation device to be separated, a phosphorus removal filter medium separated from the water to be treated by the sedimentation separation tank or solid-liquid separation device, or a phosphorus removal which is partly removed from the separated and reactivated. New treated water is supplied to filter media It characterized in that it and a filter medium dosing device to re-added to a stirred vessel which was.

  “Phosphorus contained in water to be treated” means a compound of phosphorus dissolved in water, and the total phosphorus concentration (TP) is reduced by removing it with a phosphorus removing filter medium. Is included.

The slag preferably has a Fe ₂ O ₃ content of 10 mass% to 40 mass% in order to obtain high phosphorus removal activity. The activity of the phosphorus removal filter medium gradually decreases as the phosphorus removal is continued. Therefore, the water treatment system includes a means for supplying an acidic solution for cleaning the surface of the phosphorus removal filter medium from which phosphorus has been removed for a predetermined time or a predetermined amount, and an alkaline solution for activating the phosphorus removal filter medium after the acid cleaning. And a means for supplying.

  The water treatment method of the present invention is characterized in that the average particle size of the slag is 0.1 mm or less in the water treatment method of removing phosphorus by bringing the water to be treated into contact with a phosphorus removal filter medium containing slag.

  The activity of the phosphorus removal filter medium gradually decreases as the phosphorus removal is continued. Therefore, an acidic solution is supplied to a phosphorus removal filter medium from which phosphorus has been removed for a predetermined time or a predetermined amount to clean the surface, and the phosphorus removal filter medium after acid cleaning is immersed in an alkaline solution or heat treatment to activate the filter medium. It is preferable to do.

  In order to remove phosphorus while contributing to environmental protection, it is preferable to remove phosphorus without continuously adding an alkaline solution for enhancing the phosphorus removal activity of the phosphorus removal filter medium to the water to be treated.

  According to the present invention, in removing phosphorus contained in water to be treated by bringing it into contact with a phosphorus removal filter medium containing slag, by using slag having an average particle diameter of 0.1 mm or less, phosphorus removal activity with high slag is achieved. Demonstrate. Therefore, even if the emission standard value (for example, 0.2 mg / l in total phosphorus concentration) is lowered, it is possible to remove phosphorus to a concentration below the emission standard value.

  Furthermore, according to the present invention, since a filter medium that exhibits high phosphorus removal activity is used, stable phosphorus removal can be achieved without the continuous addition of an alkaline solution for increasing the activity of slag as in the conventional method. Can be done.

1 shows an overall configuration of a water treatment system according to a first embodiment of the present invention. It is a graph which shows the correlation of the average particle diameter of slag, and the removal efficiency of phosphorus. The whole structure of the water treatment system according to 2nd Embodiment of this invention is shown. The result of the test conducted in order to confirm the effect of this invention is shown.

  Hereinafter, a water treatment system and a water treatment method according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

(First embodiment)
The water treatment system according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, the water treatment system 1 includes a raw water tank 2 that stores raw water to be treated, a first filtration device 3 that removes solid content (particularly, turbidity) contained in the water to be treated, A first supply pump 31 for supplying the water to be treated in the raw water tank 2 to the first filtration device 3, a primary treatment water tank 32 for storing the water to be treated (primary treatment water) filtered by the first filtration device 3, and The second filtration device 4 that removes phosphorus contained in the water to be treated, the second supply pump 33 that supplies the water to be treated in the primary treatment water tank 32 to the second filtration device 4, and the second filtration device 4. In addition, a secondary treated water tank 41 for storing treated water (secondary treated water) is provided. Each device is connected through a flow path such as a pipe, for example, and is configured to switch the water flow path by opening and closing valves V1-V15.

  The raw water to be treated by the water treatment system 1 is, for example, sewage or wastewater that has been subjected to biological treatment in a treatment process upstream of the system 1. Generally, the total phosphorus concentration of raw water subjected to biological treatment is 3-10 mg / l or more. However, the type of raw water is not limited, all water containing phosphorus can be treated, and the total phosphorus concentration in the raw water is not limited. However, the pH of the raw water is preferably in the neutral range of about 5.8 to 8.6.

  As the first filtration device 3, for example, a device in which filtration sand is filled in a filtration tower 34 having pipes connected to the top and bottom can be used. In the filtration tower 34, for example, a support layer 36 is formed by filling filter gravel or the like on a support member (for example, an eye plate) 35 in which a large number of water passage holes are formed in the surface. A filter sand layer 37 is formed by filling the filter sand with the filter sand. The treated water from the raw water tank 2 is supplied from the upper part of the filter tower 34, passes through the filter sand layer 37 and the support layer 36, and is discharged from the lower part of the filter tower 34. On the other hand, when backwashing to be described later is performed, the supply of water to be treated is interrupted, and the cleaning water is supplied from the lower part of the filtration tower 34 and discharged from the upper part. In addition, it can also be set as the two-layer filtration system of the filtration sand layer 37 and the anthracite layer by filling the filtration sand layer 37 with anthracite.

  As the second filtration device 4, for example, a device in which a phosphorus removal filter medium is filled in a filtration tower 42 </ b> A (42 </ b> B) having pipes connected to the top and bottom can be used. In the filtration tower 42A (42B), for example, the support member 44A (44B) is filled with filtration gravel on a support member (for example, a plate) 43A (43B) having a large number of water passage holes formed in the surface. ), And the support layer 44A (44B) is filled with a phosphorus removal filter medium to form a phosphorus removal filter medium layer 45A (45B). The water to be treated (primary treated water) is supplied from the upper part of the filtration tower 42A (42B), passes through the phosphorus removal filter material layer 45A (45B) and the support layer 44A (44B), and from the lower part of the filtration tower 42A (42B). Discharged. The second filtration device 4 has a configuration in which two filtration towers 42A (42B) having the same configuration are arranged in parallel. And filtration tower 42A (42B) which lets water flow by opening and closing valve | bulb V12-V15 can be switched. Therefore, when continuous operation is required, for example, the filtration tower 42A (42B) that switches water every time a predetermined water flow time elapses is switched, and the filtration tower 42A (42B) that is stopped will be described later. The filter medium can be operated to perform the reactivation process. It is not always necessary to use the two-column system, and one tower may be used, and conversely three or more towers may be used.

The phosphorus removal filter medium is prepared by mixing slag (Slag) having an average particle size of 0.1 mm or less, preferably in the range of 0.04 to 0.08 mm with a clay-based binder. What was granulated into the granule which falls in the range of 0.1-1.5 mm is preferable. More preferably, it is fired at 600 to 900 ° C. for about 2 hours after granulation. More preferably, the slag has an average particle size of 0.1 mm or less and a maximum particle size of 0.1 to 0.12 mm. For example, bentonite or montmorillonite can be used as the clay-based binder. The ratio of slag and binder can be, for example, slag: binder = 50 to 90%: 10 to 50%. Moreover, it is preferable to determine the packing amount of the phosphorus removal filter medium so that the superficial velocity (SV) is 3 to 10 hr ⁻¹ .

  Here, the reason for using slag having an average particle diameter of 0.1 mm or less will be described. As described in the background section, it has been studied to use slag as a phosphorus removal filter medium in the past. However, there is a concern about applicability when strict drainage standards are set. As a result of diligent research, the present inventors have found that the phosphorus removal efficiency is dramatically improved by selectively using particles having an average particle size of 0.1 mm or less, as is apparent from the test results of FIG. As a result, a phosphorus removal filter medium capable of removing phosphorus to a total phosphorus (TP) concentration of 0.2 mg / l or less has been realized. FIG. 2 shows the phosphorus removal rate when a phosphorus removal filter medium is prepared by the above-described method using slag having different average particle diameters and the treated water is actually passed through. Conventional techniques such as Patent Documents 1-4 mainly use slag having a relatively large average particle diameter. In Patent Document 1, a process of sieving is performed in advance to exclude those having an average particle diameter of 0.15 mm or less. It was. For this reason, it has not been possible to conceive that the phosphorus removal efficiency is dramatically improved by selectively using particles having an average particle diameter of 0.1 mm or less.

It is preferable that the ratio of each component which comprises slag is in the range of the component table | surface shown below. In particular, because it is can be satisfactorily removed phosphorus containing much _Fe 2 _{O 3,} it is preferable that the content of _Fe 2 _{O 3} is in the range of 10 to 40 wt%. As such slag, steel slag is preferable, and among them blast furnace slag is preferable. However, for the reasons described above, slag having an average particle diameter of 0.1 mm or less is selectively used, for example, by sieving or grinding. In addition, “others” in the component table is an impurity.

  Returning to FIG. 1, the water treatment system 1 further includes means for reactivating the phosphorus removal filter medium. In the reactivation method, unlike the conventional method, the surface of the filter medium is first washed with an acidic solution, and then the alkaline medium is supplied to activate the filter medium. As means for this, an acidic solution tank 5 that stores an acidic solution that is a cleaning liquid, an acidic solution pump 51 that supplies the acidic solution to the second filtration device 4, and an alkaline solution tank 52 that stores an alkaline solution that is an activating solution. And an alkaline solution pump 53 for supplying the alkaline solution to the second filtration device 4. Further, a cleaning liquid recovery tank 54 for recovering the acidic solution after cleaning the phosphorus removal filter medium is provided.

As the acidic solution, for example, 0.01 to 10% by mass, preferably 0.5 to 2.0% by mass of hydrochloric acid can be used. _Other, H ₂ SO _4, etc. HNO ₃ may be used. For example, NaOH can be used as the alkaline solution. Note that activation with an alkaline solution is not necessarily performed. For example, the filter medium after acid cleaning may be activated by removing it from the filtration tower 42A (42B) and baking it.

  The reactivation is preferably performed periodically at a predetermined time so that the activity of the phosphorus removal filter medium does not decrease too much. In addition to the time-based method, reactivation may be performed each time a predetermined amount of phosphorus is removed, or reactivation is performed every time the total phosphorus concentration of the secondary treatment water reaches a predetermined upper limit value. May be performed.

  Furthermore, the water treatment system 1 supplies the first treated water to the first filtration device 3 as washing water in order to wash (backwash) the first filtration device 3 that captures the solid content and gradually increases the filtration resistance. 1 A backwash pump 38 and a backwash drain 39 for collecting wash water containing turbidity discharged from the first filtration device 3 are provided. Moreover, when the water flow resistance of the 2nd filtration apparatus 4 increases, the 2nd backwash pump 46 which supplies a secondary treated water to the 2nd filtration apparatus 4 as a wash water is provided. The discharged wash water is also collected in the backwash drain 39. The backwashing is preferably performed periodically at a predetermined time so that the water flow resistance does not increase excessively. In addition, the water flow resistance may be measured by a pressure sensor, and backwashing may be performed every time the water flow resistance reaches a predetermined upper limit value.

  The valves V1 to V15 arranged in the middle of the flow paths (for example, pipes) connecting the devices are controlled to be opened or closed manually or automatically in order to switch the water flow path in each process. The valves V <b> 1 to V <b> 4 perform switching between a process step in which the water to be treated is filtered through the first filtration device 3 and a cleaning step in which the first filtration device 3 is backwashed. The valves V <b> 5 to V <b> 11 switch between a process step of passing the primary treated water through the second filtration device 4 and filtering, a step of reactivating the filter medium, and a cleaning step of backwashing the second filtration device 4. . Valves V12-V15 switch water flow between the filtration tower 42A and the filtration tower 42B.

  In principle, the water treatment system 1 of this embodiment does not add chemicals to the water to be treated from the viewpoint of environmental protection. However, if the pH of the raw water deviates from the discharge standard value, neutralization is performed by adding an acidic solution or an alkaline solution before the second filtration device 4. The pH adjustment range is, for example, a neutral region of 5.8 to 8.6. As means for that, neutralization liquid tank 6 for storing an acidic solution and / or an alkaline solution for neutralizing water to be treated, and neutralization for adding the neutralizing liquid in neutralizing liquid tank 6 to the water to be treated. A pump 61 is provided. And the to-be-processed water is sampled from the middle of piping, or the secondary treatment water tank 41, pH is measured, and a neutralization liquid is added based on the measurement result of pH. For convenience of drawing, a set of neutralization liquid tank 6 and neutralization pump 61 are described. However, when pH adjustment is performed using both an acidic solution and an alkaline solution, separate tanks and pumps are used. Be prepared.

Then, the processing method which removes phosphorus with the above-mentioned water treatment system 1 is demonstrated.
First, in the process step of removing phosphorus, the water to be treated in the raw water tank 2 is supplied to the first filtration device 3 by the first supply pump 31, and the solid content (so-called SS content) is filtered and separated for the primary treatment. Store in the water tank 32. Furthermore, although the to-be-processed water in the primary treated water tank 32 is sent to the 2nd filtration apparatus 4 with the 2nd supply pump 33, depending on pH of to-be-processed water, the neutralization pump 61 is operated and pH adjustment is performed.

  The treated water supplied to the second filtration device 4 is filtered and separated when passing through the phosphorus removal filter material layer 45 </ b> A (45 </ b> B) and stored in the secondary treated water tank 41. The treated water in the secondary treated water tank 41 is sent to a downstream process or discharged by a pump (not shown) or the like. The mechanism of phosphorus removal will be briefly explained. When the phosphorus component in the water to be treated and the slag surface come into contact, the phosphorus component reacts with the slag surface, and the phosphorus component chemically reacts with the slag surface. To be captured. Since the filtration and separation are performed chemically in this way, if phosphorus is continuously removed, the surface of the slag is covered with a reaction product of phosphorus, and the activity is reduced as the effective surface area is reduced. It is difficult to remove by physical cleaning. Therefore, the following reactivation is performed periodically.

  Reactivation is performed by interrupting the supply of water to be treated. Accordingly, the second filtration device 4 is of a two-column system, and the water to be treated is treated in one filtration tower 42A (42B), while the other filtration tower 42B (42A) is reactivated, and the process steps Is preferably not interrupted. In the reactivation, first, an acidic solution as a cleaning liquid is supplied to the filtration tower 42A (42B) by the acidic solution pump 51, and the cleaning liquid discharged from the filtration tower 42A (42B) is recovered in the cleaning liquid recovery tank 54. The acidic solution is preferably supplied at a concentration and a flow rate such that the pH in the filtration tower 42A (42B) is 1 or less. Moreover, the washing | cleaning time by an acidic solution can be 10-30 minutes, for example.

  Thus, by first washing with an acidic solution, the phosphorus reactant on the slag surface can be removed, and the activity is restored by the appearance of an effective surface of the slag. If the effective surface area is recovered, it can be reused as it is. However, for more reliable reactivation, a treatment for immersing the phosphorus removal filter medium in an alkaline solution is performed. The alkaline solution is supplied by the alkaline solution pump 53 after the supply of the acidic solution is stopped. And the state which a phosphorus removal filter medium immerses in the liquid of pH 11-14, for example is formed, and it activates by maintaining this state for 12 hours or more, for example.

  Activation with an alkaline solution may take a long time. Therefore, instead of activation with an alkaline solution, activation by firing may be performed. In this case, the phosphorus removal filter medium is taken out from the filtration tower 42A (42B) and baked at, for example, 600 to 900 ° C. for about 2 hours.

  Washing with an acidic solution has the feature that it can remove phosphorus reactants on the slag surface and can effectively use the trapped phosphorus by extracting the phosphorus contained in the washing waste water. On the other hand, there is a concern that the particle size of the slag gradually decreases as a result of acid cleaning. Therefore, when the number of times of acid washing reaches a large number, it is preferable to replace the phosphorus removal filter medium. The phosphorus removal filter medium after use can be reused as a soil conditioner, agricultural fertilizer and the like.

  Moreover, when the water flow resistance of the 1st filtration apparatus 3 rises, the 1st supply pump 31 is stopped and a line is switched from a process process to a washing process by opening and closing valve | bulb V1-V4. Then, wash water is supplied from the lower part of the filter tower 34 by the first backwash pump 38 to wash the filter sand. The washing wastewater discharged from the upper part of the filtration tower 34 is collected in the backwash drainage tank 39. Even when the water flow resistance of the second filtration device 4 increases, backwashing is performed in the same manner.

  According to the above-described embodiment, slag having a high average particle diameter of 0.1 mm or less is mixed with a clay-based binder, and the slag exhibits a high phosphorus removal activity by using a phosphorus removal filter medium granulated into granules. . Even if the activity is lowered to the emission standard value (for example, 0.2 mg / l in total phosphorus concentration), the activity is high enough to remove phosphorus to a concentration below the emission standard value.

  Furthermore, according to the above-described embodiment, by using a phosphorus removal filter medium that exhibits high phosphorus removal activity, an alkaline solution for increasing the activity of the phosphorus removal filter medium is not continuously added to the water to be treated as in the conventional method. In addition, stable phosphorus removal can be performed while contributing to environmental protection.

  Furthermore, according to the above-described embodiment, in the reactivation of the phosphorus removal filter medium, by first performing washing with an acidic solution, it is possible to remove the phosphorus reactant on the slag surface, and to effectively remove the slag surface. The activity can be restored by the appearance of. Furthermore, if the phosphorus contained in the acid waste water is extracted, the captured phosphorus can be used effectively.

(Second Embodiment)
Next, a water treatment system according to the second embodiment will be described with reference to FIG. The first embodiment described above has a filtration tower type apparatus configuration in which the water to be treated is passed, but the water treatment system according to the present embodiment is agitated by adding a phosphorus removal filter medium to the water to be treated and stirring. It is a tank-type device configuration.

  The water treatment system 100 includes a stirring tank 7 having a supply port 71 of water to be treated on one end side and a discharge port 72 on the other end side. The agitation tank 7 is partitioned into a plurality of regions by a partition wall 73, and forms a first agitation region 74, a second agitation region 75, and a filter material recovery region 76 that also serve as a filter material addition region in order from one end side. . The water to be treated in the raw water tank 2 is continuously supplied to the supply port 71 by the supply pump 31, passes through each region (74 → 75 → 76), and is discharged from the discharge port 72. Note that the regions 74 to 76 are not necessarily formed by the partition wall 73, and the regions 74 to 76 may be formed by independent tanks.

  The first agitation region 74 that also serves as a filter medium addition region is a region in which the phosphorus removal filter medium is added to the water to be treated, and is a region in which the water to be treated to which the phosphorus removal filter material is added is agitated. A stirring device 74a having a rotating stirring blade is arranged. The 2nd stirring area | region 75 is also an area | region which stirs the to-be-processed water to which the phosphorus removal filter medium was added, for example, the stirring apparatus 75a provided with the stirring blade rotated by a drive motor is arrange | positioned. The first and second agitation regions 74 and 75 are regions for substantially removing phosphorus, and the reaction of the phosphorus component and the slag surface is promoted by uniformly dispersing the phosphorus removal filter medium in this region. Therefore, the volumes of the first and second stirring regions 74 and 75, the supply flow rate of the water to be treated, and the like are designed so that the residence time is sufficient to decompose phosphorus to a predetermined target value or less. The supply flow rate is adjusted based on the detection result of the flow meter 31a. If phosphorus can be decomposed to a predetermined target value or less, only the first stirring region 75 may be used, and conversely, the number of stirring regions may be increased.

  The filter medium recovery area 76 is an area for separating the phosphorus removal filter medium from the water to be treated. FIG. 3 shows, as an example, a sedimentation separation tank that performs solid-liquid separation using the specific gravity difference between the water to be treated and the filter medium. A filter medium recovery pump 8 is connected to the bottom of the settling tank to extract the slurry containing the phosphorus removal filter medium from the bottom. On the other hand, a discharge port 72 is connected to the upper side of the settling tank, so that clear water not containing the phosphorus removal filter medium overflows and is discharged. However, the filter medium recovery region 76 only needs to separate and recover the phosphorus removal filter medium from the water to be treated, and can be replaced with another solid-liquid separator. Examples of other solid-liquid separators include, for example, a centrifugal separator such as a decanter, a filtration device, and the like.

  The filter medium recovery pump 8 is connected to the cyclone 81 via a flow path such as a pipe, and supplies the slurry liquid containing the phosphorus removal filter medium to the cyclone 81. In order to control the liquid level in the filter medium recovery area 76, the filter medium recovery pump 8 performs ON-OFF control based on the detection result of the liquid level gauge 76a, for example. The cyclone 81 separates the phosphorus removal filter medium from the slurry and supplies it to the recovery tank 82, and returns the separated water to the first stirring area 74 that also serves as the filter medium addition area through a flow path such as a pipe. The phosphorus removal filter medium in the recovery tank 82 is added again to the first stirring area 74 that also serves as the filter medium addition area, and thus the phosphorus removal filter medium is circulated and used. The valve 8a opens and closes when the filter medium is deposited on the bottoms of the first stirring area 74 and the second stirring area 75, and lifts the accumulated filter medium using the liquid flow of the filter medium recovery pump 8. Used for.

  However, since the activity of the phosphorus-removing filter medium gradually decreases by removing phosphorus, a part of the phosphorus-removing filter medium in the recovery tank 82 is withdrawn periodically or continuously to perform the reactivation process. In the reactivation, as described above, the phosphorus removal filter medium is first washed with an acidic solution and then immersed in an alkaline solution or calcined. The reactivated phosphorus removal filter medium is added to the first stirring region 74 which also serves as the filter medium addition region by a filter medium addition device 83 such as a hopper. The replenishment of the phosphorus removal filter medium is also performed by the filter medium addition device 83. The filter medium adding device 83 is configured to supply the filter medium using, for example, compressor air (compressed air) supplied via a dry air unit 84 that removes moisture as a driving force.

  As the phosphorus removal filter medium used in the present embodiment, for example, a granular material having an average particle diameter after granulation in the range of 0.1 to 0.3 mm is preferably used. However, the present invention is not limited to this, and the same one as in the first embodiment may be used, or slag having an average particle diameter of 0.1 mm or less may be used as it is without granulation. Even when the slag having an average particle diameter of 0.1 mm or less is used as it is, the firing efficiency is stabilized by firing.

  Also in such an embodiment, the same effect as the first embodiment can be obtained. Furthermore, in comparison with the filtration tower system, this embodiment has an advantage of improving the reaction rate and reaction efficiency by increasing the contact area.

Example 1
Then, Example 1 performed in order to confirm the effect of this invention is demonstrated. This example corresponds to the filtration tower system of the first embodiment. In Example 1 in which a filtration column (φ75 mm, height 1000 mm) is filled with a phosphorus removal filter medium, and raw water is passed to remove phosphorus. is there. More specifically, the filtration column was filled with a phosphorus removal filter medium so that the layer thickness was 700 mm, and raw water having a total phosphorus concentration of 10 mg / l was passed through so that SV = 10 hr ⁻¹ .

The results of Example 1 are shown in Table 2. As is clear from the results in Table 2, it was confirmed that a high removal rate of 95% or more was achieved and phosphorus could be removed to a target value (0.2 mg / l) or less.

(Example 2)
This example is a scale-up test using a pilot plant. More specifically, a filter tower (φ850 mm, height 2500 mm) is filled with a phosphorus removal filter medium so that the layer thickness is 800 mm, and water to be treated having a total phosphorus concentration of 3 mg / l is set to SV = 5 hr ⁻¹ . The water was passed.

The results of Example 2 are shown in Table 3. As is clear from the results in Table 3, it was confirmed that a high removal rate of 97% or more was achieved and phosphorus could be removed to a target value (0.2 mg / l) or less.

(Example 3)
This example corresponds to the stirring tank method of the second embodiment, and the concentration of phosphorus was measured over time using a stirring tank 7 having a size of L1580 mm × D1440 mm × H3080 mm, and the removal rate was calculated. Test 1-3 set the ratio of the filter medium with respect to raw | natural water to about 0.7 mass%. In Test 4-5, the ratio of the filter medium to the raw water was set to about 0.3 mass%. Other detailed test conditions and test results are shown in FIG.

  As is clear from the test results in FIG. 4, a removal rate exceeding 90% was achieved in all tests, and phosphorus could be removed to a target value (0.2 mg / l) or less. In this test, the phosphorus concentration of the raw water is set to about 3 mg / l. However, the feed rate, the amount of filter medium added, or the filter medium and raw water in the agitation tank are also applied to raw water of higher or lower concentration. It is possible to cope by adjusting the contact time. Moreover, based on the result of Test 4-5, even if the ratio of the filter medium to the raw water was about 0.3% by mass, a high removal rate could be achieved, and the advantage of saving the amount of filter medium used could be confirmed.

  Although the present invention has been described in detail with reference to specific embodiments, various substitutions, modifications, changes, etc. in form and detail are defined in the claims. It will be apparent to those skilled in the art that this can be done without departing from the spirit and scope. Therefore, the scope of the present invention should not be limited to the above-described embodiments and the accompanying drawings, but should be determined based on the description of the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Water treatment system 2 Raw water tank 3 1st filtration apparatus 4 2nd filtration apparatus 42A, 42B Filter tower 45A, 45B Phosphorus removal filter material layer 5 Acidic solution (washing liquid) tank 51 Acidic solution pump 52 Alkaline solution (reactivation solution) tank 53 Alkaline solution pump

Claims (3)

In a water treatment system for removing phosphorus contained in water to be treated by bringing it into contact with a phosphorus removal filter medium,
The phosphorus-removing filter medium is obtained by mixing slag having an average particle size of 0.1 mm or less with a clay-based binder, granulating the slag into particles having an average particle size of 0.3 mm or less, and firing.
The water treatment system comprises:
An agitation tank in which the phosphorus removal filter medium is added to the water to be treated and agitated;
A filter medium addition device for adding the phosphorus removal filter medium to the stirring tank;
A settling separation tank or a solid-liquid separation device for solid-liquid separation of water to be treated containing the phosphorus removal filter medium discharged from the stirring tank, and separating the phosphorus removal filter medium from the water to be treated from which phosphorus has been removed;
The phosphorus removal filter medium separated from the water to be treated by the sedimentation separation tank or the solid-liquid separation apparatus, or the phosphorus removal filter medium that has been partially reactivated from the separated water was supplied with new water to be treated. A water treatment system comprising: a filter medium addition device that re-adds to a stirring tank . The slag, water treatment system of claim 1, wherein the content of Fe ₂ O ₃ is in the range of 10% to 40% by weight.   The water treatment system comprises means for supplying an acidic solution for cleaning the surface of the phosphorus removal filter medium from which phosphorus has been removed for a predetermined time or a predetermined amount, and an alkaline solution for activating the phosphorus removal filter medium after the acid cleaning. The water treatment system according to claim 1, further comprising a supply unit.