JP2007222835A - Turbid water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbid water treatment apparatus capable of obtaining a desired turbid water treatment performance without deteriorating economical efficiency even in a dilute raw water concentration. <P>SOLUTION: This turbid water treatment apparatus is provided with a raw water tank 1 supplied with treating object water containing fine solid particles suspended therein; a solid/liquid separation tank 2 separating the treating object water sent from the raw water tank 1 into separated water and slurry; a cleaned water line CL taking out the separated water of the solid/liquid separation tank 2 for treating; and a solidification line SL taking out the slurry in the solid/liquid separation tank 2 for solidifying. A control circuit 100 is provided having a return line 26 returning the slurry of the solidification line SL to the raw water tank 1, and a densitometer 14 is provided detecting concentration of the treating object water. When the concentration detected by the densitometer 14 is below a concentration set in advance, the slurry is returned to the raw water tank 1 via the return line 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a turbid water treatment apparatus for purifying turbid water generated in various construction works to a level at which it can be discharged into a natural water system or the like.

  2. Description of the Related Art Conventionally, turbid water treatment apparatuses that purify turbid water generated in various civil engineering construction works such as subway construction and tunnel construction and discharge them to natural water systems such as rivers and lakes are known.

As such a muddy water treatment device, a flocculant is added to the water to be treated (turbid water) sent from the raw water tank, and in the solid-liquid separation tank, the separated water and the slurry of the supernatant are separated. For example, Patent Document 1 discloses a turbid water treatment apparatus that discharges into a natural water system such as a river or a lake after adding a neutralizer to satisfy an environmental standard value.
JP 2002-205075 A

  To-be-treated water (raw water) discharged from the construction site described above has an unstable suspended suspended solid concentration and is often dilute.

  As described above, when the concentration is dilute, it takes time for the coagulation sedimentation treatment of the slurry in the solid-liquid separation tank. For this reason, in the solid-liquid separation tank, the solid-liquid separation is not sufficiently performed, and a lot of micro suspended matters are mixed in the separated water, and the pH concentration and the SS concentration of the treated water may not be able to achieve the standard value. there were.

  Therefore, in such a case, conventionally, the reference value of the pH concentration and the SS concentration has been achieved by increasing the amount of the flocculant to be added and increasing the solid-liquid separation speed.

  However, as described above, the method of increasing the addition amount of the flocculant has a problem that the use amount of the flocculant increases and the economic efficiency deteriorates.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a turbid water treatment apparatus capable of obtaining the expected turbid water treatment performance without deteriorating the economy even when the concentration is low. .

  In order to achieve the above-mentioned object, the invention described in claim 1 includes a raw water tank supplied with treated water in which fine solid particles are suspended in water, and a treated water sent from the raw water tank. A solid-liquid separation tank that separates the separated water into a slurry that is clear and a slurry in which the fine solid particles are concentrated, a water purification path that takes out the separated water from the solid-liquid separation tank, and a slurry in the solid-liquid separation tank. A turbid water treatment apparatus comprising a solidification path for taking out and individualizing, and a slurry return means for returning the slurry of the solidification path to the water to be treated is provided, and suspended suspended solids concentration of the water to be treated And a control means for performing return control for returning the slurry to the water to be treated by operating the slurry return means when the concentration detected by the concentration sensor is equal to or lower than a preset concentration. Has been And wherein the door.

  The invention described in claim 2 is the turbid water treatment apparatus according to claim 1, wherein the slurry return means is configured to return the slurry of the solidification path to the raw water tank and is stored in the raw water tank. Further, stirring means for stirring the treated water is provided.

  The invention described in claim 3 is the turbid water treatment apparatus according to claim 1 or 2, wherein the solidification path is a slurry in which slurry separated in a solid-liquid separation tank is sent to a slurry storage tank by a delivery pump. A feed line, and a pressure feed line that feeds the slurry stored in the slurry storage tank to the press device by a pressure feed pump, wherein the slurry return means is provided in the slurry delivery line downstream of the feed pump. And a switching valve for selectively sending the slurry sent from the delivery pump to the slurry storage tank and the raw water tank.

  Further, the invention according to claim 4 is the turbid water treatment apparatus according to any one of claims 1 to 3, wherein the flocculant is added to the raw water delivery line for sending the treated water from the raw water tank to the solid-liquid separation tank. An addition means for adding is provided.

  In the muddy water treatment apparatus of the present invention, the water to be treated supplied to the raw water tank is sent to the solid-liquid separation tank, where it is separated into separated water and slurry. Then, the separated water is sent to the purified water path, where it is discharged into the natural system as purified water. On the other hand, the slurry is sent to a solidification path and solidified.

  Here, when the concentration detected by the concentration sensor is equal to or lower than a preset concentration, the control means operates the slurry return means, whereby the slurry in the solidification path is returned to the water to be treated. Therefore, the concentration of the water to be treated is increased by the amount of slurry returned.

  Therefore, the concentration of the water to be treated can be stabilized at a predetermined concentration or more, and the solid-liquid separation performance in the solid-liquid separation tank can be stabilized.

  As described above, in the present invention, without increasing the amount of the flocculant, the performance of the solid-liquid separation tank is stabilized by using the slurry that is a precipitate of fine solid particles originally contained in the water to be treated. As a result, the solid-liquid separation performance can be stabilized at a lower cost than when the amount of the flocculant is increased as in the prior art.

  Furthermore, in the invention described in claim 2, the slurry is returned to the raw water tank by the slurry return means, the stirring means is operated, the returned slurry is mixed with the water to be treated, and the concentration of the water to be treated is made uniform. .

  Therefore, the concentration of the water to be treated can be further stabilized.

  In a third aspect of the invention, during normal times when the slurry return means is not operated, the slurry precipitated in the solid-liquid separation tank is sent to the slurry storage tank by the feed pump.

  On the other hand, at the time of the return operation of the slurry return means, the delivery pump that sends the slurry of the solid-liquid separation tank to the slurry storage tank is operated, and the switching valve is switched to the side that sends the slurry to the raw water tank.

  Thereby, the slurry which settled in the solid-liquid separation tank is sent to a raw | natural water tank via the return line branched from the slurry delivery line.

  As described above, in the present invention, when returning the slurry to the raw water tank, normally, the delivery pump used to send the slurry from the solid-liquid separation tank to the slurry storage tank is shared. Compared with the case of using, the configuration can be simplified and the manufacturing cost can be reduced.

  In the invention according to claim 4, since the flocculant is added before the solid-liquid separation tank, the sedimentation of the slurry in the solid-liquid separation tank is promoted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
1 is an overall view showing a muddy water treatment apparatus A according to Embodiment 1. FIG.

  The muddy water treatment apparatus A according to Embodiment 1 includes a raw water tank 1, a solid-liquid separation tank 2, a treated water tank 3, a sludge storage tank 4, and a press device 5.

  The raw water tank 1 is installed at a construction site or the like, and treated water (raw water) is supplied from a pretreatment tank 6 by a raw water supply line 62 by a pumping pump 61.

  The pretreatment tank 6 includes a deposition tank 6a that deposits large particles such as gravel particles in water to be treated by weight and deposits them on the bottom, and an upper body in which fine fixed particles in the upper part of the deposition tank 6a are suspended. Raw water storage tank 6b for storing primary treated water (treated water). Moreover, the pump 61 sends the primary treated water of the raw water storage tank 6b to the raw water tank 1 as treated water.

  The raw water tank 1 is provided with a raw water pump 11, a stirrer 12, a water level meter 13, and a concentration meter 14.

  The raw water pump 11 sends the water to be treated in the raw water tank 1 to the solid-liquid separation tank 2 through the raw water transfer line 15. The stirrer 12 agitates the water to be treated in the raw water tank 1 to make the suspended suspended solids concentration (hereinafter referred to as SS concentration) of the water to be treated generally uniform, and is always driven. The water level gauge 13 detects the water level of the raw water tank 1.

  The raw water pump 11 starts operating when the water level rises to a preset working water level based on the water level detected by the water level gauge 13, and stops operating when the water level falls to a preset stop water level. To do.

  The densitometer 14 detects the SS concentration of the water to be treated in the raw water tank 1, and this detection signal is sent to the control circuit 100.

  In the middle of the raw water transfer line 15 from the raw water tank 1 to the solid-liquid separation tank 2, a flow meter 16 and a mixer 7 are provided in order from the upstream side, and further mixed with the flow meter 16 in the raw water transfer line 15. A carbon dioxide line 81 and a flocculant line 91 are connected to the machine 7.

  The flow meter 16 detects the water supply flow rate to the solid-liquid separation tank 2.

  The carbon dioxide line 81 supplies carbon dioxide as a neutralizing agent for adjusting pH from the carbon dioxide supply means 8. The carbon dioxide supply means 8 includes a plurality of carbon dioxide cylinders 82 storing liquefied gas, and a vaporizer 83 that applies heat to the liquefied gas to vaporize it.

  Note that the amount of carbon dioxide supplied through the carbon dioxide line 81 is adjusted by a control valve 84. Further, the opening degree of the control valve 84 is adjusted by the pH controller 85 according to the pH concentration of the solid-liquid separation tank 2.

  The flocculant line 91 supplies PAC (polyaluminum chloride) as a flocculant from the PAC supply means 9. The PAC supply means 9 includes a PAC tank 92 that stores the PAC, and a PAC pump 93 that sends the PAC in the PAC tank 92.

  The mixer 7 mixes water to be treated, carbon dioxide gas, a flocculant, and a polymer flocculant described later, and catches a rough SS. The polymer flocculant is a large substance that adsorbs minute suspended substances in water to be precipitated, and is supplied from the polymer flocculant supply means 10 through the polymer line 101. The polymer flocculant supply means 10 is provided in the middle of the polymer line 101 and the polymer dissolution tanks 102 and 103 for dissolving the powdered polymer flocculant with purified water described later, and the polymer dissolution tanks 102 and 103. And a polymer pump 104 for feeding the polymer flocculant stored in the container.

  The solid-liquid separation tank 2 settles suspended suspended solids (hereinafter referred to as SS), which are fine solid particles in the water to be treated, into slurry in which these SS are concentrated, and purified water from which SS has been removed more than a predetermined amount. It is a tank to be separated, and a sludge scraping device 21 is provided at the bottom.

  In addition, a purified water line 22 for transferring purified water to the treated water tank 3 by water head pressure is connected to the upper part of the solid-liquid separation tank 2.

  On the other hand, a sludge line 24 is connected to the bottom of the solid-liquid separation tank 2 to transfer the slurry settled on the bottom to the sludge storage tank 4 by driving the mud pump 23. Further, the sludge line 24 is connected to the raw water tank 1 by a return line 26 branched at a branch point 25 provided downstream of the mud pump 23.

  The sludge line 24 and the return line 26 are provided with switching valves 27a and 27b for selectively transferring the slurry sent from the mud pump 23 to either the sludge storage tank 4 or the raw water tank 1. Yes. The switching valves 27a and 27b are rubber-type pinch valves that are responsive and have excellent wear resistance, and are opened and closed by driving an instrumentation compressor 27c.

  The treated water tank 3 is provided with a discharge line 31 at the upper part for overflowing the stored purified water and discharging it to the natural system. The treated water tank 3 is provided with a turbidimeter 32 that measures the turbidity of the stored purified water and a pH concentration recorder 33 that measures the pH concentration of the purified water.

  Furthermore, a backflow line 35 for transferring the stored purified water by a backwash pump 34 is connected to the treated water tank 3. The backflow line 35 includes a branch line 35a that reaches the polymer dissolution tanks 102 and 103, a branch line 35b that reaches the mud feed pump 23, and a press-fit pump, which will be described later, at branch points 36 and 37 downstream of the backwash pump 34. A branch line 35c leading to 41 and a branch line 35d leading to a filter cloth cleaning pump 51 described later are branched.

  The purified water supplied by these branch lines 35a, 35b, 35c, and 35d is used as chemical dissolving water in the polymer dissolution tanks 102 and 103, and used as sealing water in the mud pump 23 and the press-fitting pump 41. The filter cloth cleaning pump 51 is used for cleaning the filter cloth of the press device 5 described later.

  The path from the solid-liquid separation tank 2 to the discharge, that is, the path including the water purification line 22, the treated water tank 3, and the discharge line 31 described above is the water purification path CL.

  The sludge storage tank 4 is a tank that temporarily stores excess slurry, and is connected to a press-in line 42 that includes a press-in pump 41 that sends the stored slurry to the press device 5. The sludge storage tank 4 is provided with a stirring pump 43 for preventing sedimentation of the slurry and a water level meter 44 for detecting the water level of the slurry.

  The press device 5 presses the slurry between a filter plate (not shown) and the filter cloth to perform dehydration to form a dewatered cake DC that is a plate-shaped sludge. Further, the press device 5 is provided with a filtrate receiving tank 52 that receives and measures the filtrate produced when the dehydrated cake DC is formed. In addition, the filtrate received in the filtrate receiving tank 52 is returned to the raw water tank 1 by the filtrate head 53 with a water head pressure.

  The path from the solid-liquid separation tank 2 described above to the formation of the dewatered cake DC, that is, the path including the sludge line 24, the sludge storage tank 4, the press-in line 42, and the press device 5 is the solidification path SL.

Next, the operation of the first embodiment will be described.
The flow of muddy water treatment in the muddy water treatment apparatus A according to the first embodiment will be briefly described. First, the water to be treated (raw water) discharged from a construction site or the like is supplied to the raw water tank 1 and the raw water transfer line 15 , After adding the flocculant, carbon dioxide gas, and polymer flocculant, it is sent to the solid-liquid separation tank 2.

  In the solid-liquid separation tank 2, the SS contained in the water to be treated is settled and separated into the supernatant purified water (separated water) and the precipitated slurry. At this time, it is contained in the water to be treated by the flocculant. The SSs are combined to promote the sedimentation of the slurry.

  And the purified water isolate | separated by the solid-liquid separation tank 2 is sent to the treated water tank 3, and is discharged | emitted from this treated water tank 3 to a natural water system. In this treated water tank 3, turbidity and pH are always detected, and treated water that satisfies the reference value is discharged.

  On the other hand, the slurry precipitated in the solid-liquid separation tank 2 is sent to the sludge storage tank 4 and stored at one end, and then sent to the press device 5 to be dehydrated to form a dehydrated cake DC. This dewatered cake DC is discarded by landfill disposal or the like.

  The above muddy water treatment flow is when the SS concentration of the water to be treated detected by the densitometer 14 is larger than the operation start set concentration which is a preset concentration. At this time, the control circuit 100 operates the switching valve. 27 a and 27 b are in a state where the solid-liquid separation tank 2 and the sludge storage tank 4 are connected by the sludge line 24.

  On the other hand, when the SS concentration of the water to be treated detected by the densitometer 14 is equal to or lower than the operation start set concentration, the control circuit 100 switches the switching valves 27a and 27b to change the slurry sending direction by the mud pump 23. The mud pump 23 is operated on the return line 26 side.

  Thereby, the slurry settled in the solid-liquid separation tank 2 is returned to the raw water tank 1 and mixed and stirred with the water to be treated by the operation of the stirrer 12, so that the SS concentration in the raw water tank 1 is made uniform.

  Therefore, the SS concentration of the water to be treated in the raw water tank 1 is increased by the amount of slurry returned. Thereafter, when the SS concentration detected by the densitometer 14 exceeds a preset operation stop set concentration (set operation stop set concentration ≧ operation start set concentration), the switching valves 27a and 27b return to their original states. Then, the operation of the mud pump 23 is stopped.

  Therefore, in the muddy water treatment apparatus of the first embodiment, the SS concentration of the water to be treated in the raw water tank 1 is always kept at a concentration equal to or higher than a predetermined operation start set concentration at which the operation of the solid-liquid separation tank 2 is stable. .

  This operation start set concentration is set to an SS concentration within a range in which the desired solid-liquid separation performance can be obtained in the solid-liquid separation tank 2, and thus the solid-liquid separation performance in the solid-liquid separation tank 2 is stabilized. Can be achieved.

  As described above, in the first embodiment, the performance of the solid-liquid separation tank is stabilized by using the slurry that is a precipitate of fine solid particles originally contained in the water to be treated without increasing the amount of the flocculant. As a result, the solid-liquid separation performance can be stabilized at a lower cost than when the amount of the flocculant is increased as in the prior art.

  Furthermore, since the slurry returned to the raw water tank 1 is mixed with the water to be treated by the constantly driven stirrer 12, the SS concentration of the raw water tank 1 is made uniform, so that the SS concentration of the water to be treated is further stabilized. Can be achieved.

  In addition, when the slurry precipitated in the solid-liquid separation tank 2 is returned to the raw water tank 1, the mud pump 23 performs the slurry. This mud pump 23 is usually a pump for feeding from the solid-liquid separation tank 2 to the sludge storage tank 4. As described above, the mud pump 23 is commonly used for normal slurry transfer and for returning to the raw water tank 1, so that the configuration can be simplified compared to using a dedicated pump for each. Manufacturing costs can be reduced.

  (Embodiment 2)

  Next, the muddy water treatment apparatus B of Embodiment 2 will be described based on FIG. In the description of the second embodiment, the same or equivalent parts as those in the first embodiment are denoted by the same reference numerals, and different parts will be mainly described.

  The muddy water treatment apparatus B of Embodiment 2 is configured to return the slurry stored in the sludge storage tank 4 to the raw water tank 1. That is, a return line 200 that connects the sludge storage tank 4 and the raw water tank 1 is provided, an open / close switching valve 201 that opens and closes the return line 200, and a return pump that sends the slurry stored in the sludge storage tank 4 to the raw water tank 1. 202.

  The opening / closing switching valve 201 and the return pump 202 are controlled by the control circuit 203. That is, when the SS concentration detected by the densitometer 14 is higher than the operation start set concentration, the open / close switching valve 201 is closed and the return pump 202 is stopped.

  On the other hand, when the SS concentration detected by the densitometer 14 is equal to or lower than the operation start set concentration, the open / close switching valve 201 is opened and the return pump 202 is operated. Therefore, the slurry stored in the sludge storage tank 4 is returned to the raw water tank 1 and mixed and stirred with the water to be treated.

  The slurry is returned until the SS concentration of the raw water tank 1 exceeds the operation stop set concentration, as in the first embodiment.

  As described above, even in the muddy water treatment apparatus B according to the second embodiment, the SS concentration of the water to be treated in the raw water tank 1 is always equal to or higher than the predetermined operation start set concentration, as in the first embodiment. When the slurry is returned to the raw water tank 1, the effect of stabilizing the solid-liquid separation performance in the solid-liquid separation tank 2 can be obtained at low cost without increasing the amount of the flocculant. The effect that the SS concentration of the water to be treated can be made uniform by stirring with the stirrer 12 is obtained.

  As described above, the first and second embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the first and second embodiments, and the gist of the present invention is not deviated. Design changes are included in the present invention.

  For example, in Embodiments 1 and 2, what is installed at a construction site has been shown, but the present invention is not limited to such an installation type but can also be applied to a mobile type.

  Moreover, although Embodiment 1 and 2 showed what discharges purified water as the purified water path | route CL, it is not limited to this, It is good also as a path | route which reuses purified water.

  Moreover, in Embodiment 1, 2, although the example which adds the carbon dioxide gas as a neutralizing agent upstream of the solid-liquid separation tank 2 was shown, it adds in the middle of a discharge path, ie, the water purification line 22 or the treated water tank 3. You may make it do.

  In the first and second embodiments, when the slurry is returned to the raw water tank 1, the pumps (the mud pump 23 and the return pump 202) are operated until the SS concentration of the raw water tank 1 reaches a predetermined concentration. However, the operation is not limited to this. For example, when the pump is operated for a predetermined time and a predetermined amount of slurry is returned to the raw water tank 1, the pump is temporarily stopped, and during that time, the agitator 12 is stirred for a predetermined time to achieve uniform SS concentration in the raw water tank 1. This operation may be repeated several times. Further, the operation time of the pump may be lengthened as the difference is larger based on the difference between the detected concentration and the operation start set concentration.

  In the first and second embodiments, as the slurry return means, the slurry is returned to the raw water tank 1. However, if the slurry is returned to the water to be treated before being processed in the solid-liquid separation tank 2, this slurry is returned. The position to return is not limited to the raw water tank 1. That is, if it is Embodiment 1, 2, you may make it return to the middle of the raw | natural water transfer line 15 arrange | positioned between the raw | natural water tank 1 and the solid-liquid separation tank 2, or the mixer 7, for example. In this case, it is preferable to provide a means for promoting mixing with the water to be treated such as a mixer at the return portion of the slurry. Alternatively, a pipe for supplying the water to be treated is added in the middle of the return line 26 as the slurry returning means, and the slurry is mixed with the water to be treated and then returned to the raw water tank 1 or the middle of the raw water transfer line 15. It may be.

It is a general view which shows the muddy water processing apparatus of Embodiment 1 of this invention. It is a general view which shows the muddy water processing apparatus of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Solid-liquid separation tank 3 Treated water tank 4 Sludge storage tank 5 Press apparatus 9 PAC supply means (addition means)
10 Polymer flocculant supply means (addition means)
12 Stirrer 14 Density meter (Concentration sensor)
23 Mud pump (slurry return means)
26 Return line (slurry return means)
27a, 27b selector valve (slurry return means)
100 Control circuit (control means)
200 Return line (slurry return means)
201 Open / close switching valve (slurry return means)
202 Return pump (slurry return means)
203 Control circuit (control means)
DC dewatering cake CL water purification route SL solidification route

Claims (4)

A raw water tank to which treated water in which fine solid particles are suspended in water is supplied;
A solid-liquid separation tank that separates the water to be treated sent from the raw water tank into a separated water that is a supernatant and a slurry in which the fine solid particles are concentrated;
A water purification path for removing and treating the separated water from the solid-liquid separation tank,
A solidification path for taking out and solidifying the slurry of the solid-liquid separation tank;
A muddy water treatment apparatus comprising:
A slurry return means for returning the slurry of the solidification path to the water to be treated is provided,
A concentration sensor for detecting the suspended suspended matter concentration of the treated water is provided,
When the concentration detected by the concentration sensor is equal to or lower than a preset concentration, turbid water is provided with control means for performing return control for operating the slurry return means to return the slurry to the water to be treated. Processing equipment. The slurry return means is configured to return the slurry of the solidification path to the raw water tank,
The muddy water treatment apparatus according to claim 1, wherein the raw water tank is provided with a stirring means for stirring the stored water to be treated. The solidification path includes a slurry delivery line for sending the slurry separated in the solid-liquid separation tank to the slurry storage tank by a delivery pump, and a pressure feed line for feeding the slurry stored in the slurry storage tank to the press device by a pressure feed pump. Prepared,
The slurry return means selects a return line branched from a branch portion provided in a slurry delivery line downstream from the delivery pump to a raw water tank, and a slurry sent from the delivery pump to a slurry storage tank and a raw water tank. The turbid water treatment apparatus according to claim 1, further comprising: a switching valve that automatically sends the switching valve.   The turbid water according to any one of claims 1 to 3, wherein an addition means for adding a flocculant is provided in a raw water delivery line for sending treated water from the raw water tank to a solid-liquid separation tank. Processing equipment.

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