JP2010194463A - Water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment apparatus, which carries out a magnetic flocculation method by charging a flocculant and a magnetic powder into wastewater and removing a produced magnetic floc, capable of continuously and efficiently recovering the magnetic powder from sludge with installations simply configured and reusing the recovered magnetic powder. <P>SOLUTION: The flocculant and the magnetic powder are charged into the water to be treated to form the magnetic floc, the floc is magnetically collected to clean the water to be treated, and the sludge produced in parallel and including the magnetic floc is pressurized and sent, heated in a reactor at a high temperature and pressure. The magnetic floc is collected from the sludge after passing through a back pressure valve, and then the magnetic powder is used again. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water treatment apparatus in which a flocculant or magnetic powder is introduced into sewage and purified by agglomeration magnetic separation.

  As a technique for purifying sewage, there is a technique called flocculation magnetic separation in which a flocculant and magnetic powder are introduced into the sewage and the generated magnetic flocs are recovered by magnetic force to obtain purified water. In this method, sludge containing magnetic powder is generated, but the generated sludge must be discarded as industrial waste, and this disposal cost increases the running cost. If this sludge can be reduced, the running cost and the amount of generated sludge can be reduced.

  As a technique for solving this problem, as disclosed in Patent Documents 1 and 2, a technique for decomposing sludge containing magnetic powder by a hydrothermal reaction to reduce the volume of sludge is shown.

JP 11-123399 A Japanese Patent Laid-Open No. 11-207399

  In the above disclosed invention, sewage is purified by coagulation magnetic separation, sludge generated at that time is hydrothermally treated at high temperature and high pressure, and magnetic powder is recovered by magnetic separation in a high temperature and high pressure line. Therefore, it is necessary to make the magnetic separation device a structure having high heat resistance and high strength. Therefore, the structure of the apparatus is complicated, the manufacturing cost is high, and maintenance is complicated.

  Further, in the above disclosed invention, the total amount of generated sludge is decomposed by high-temperature and high-pressure hydrothermal treatment, so that the input energy is large.

  In order to solve the above problems, the present invention treats sewage with a simple apparatus configuration and low running cost, recovers magnetic powder from the generated sludge and reuses it, thereby reducing sludge volume and running. It aims at providing the water treatment apparatus which can reduce cost.

  In order to solve the above-mentioned problem, the water treatment device according to claim 1 includes at least one flocculant injection device for injecting a flocculant into sewage to be treated, and a magnetic powder injection device for injecting magnetic powder. At least one stirring device that forms magnetic flocs by stirring, a magnetic floc separating device that separates the generated magnetic flocs, a first pressure pump that feeds sludge that is an aggregate of magnetic flocs, A first reactor heated by a heater while pressurized sludge passes through, a back pressure valve that discharges sludge to atmospheric pressure while maintaining a high pressure in the reactor, and magnetic powder from the discharged sludge And a transfer device for transferring the recovered magnetic powder to the magnetic powder charging device.

  The water treatment device according to claim 2 is provided in the downstream of the first reactor in claim 1, and is a solid-liquid separation device for separating into a supernatant and sludge, a back pressure valve for discharging the supernatant, And a second reactor for reheating the separated sludge.

  The water treatment device according to claim 3 is provided in the downstream of the first reactor in claim 1, and is a solid-liquid separation device for separating the supernatant into sludge and sludge, and the second for feeding the separated sludge. And a second reactor for heating the pressurized sludge again.

  The water treatment device according to claim 4 is provided in the downstream of the first reactor in claim 1, and is a solid-liquid separation device for separating into a supernatant and sludge, a back pressure valve for discharging the supernatant, A second pressurizing pump for feeding the separated sludge and a second reactor for heating the pressurized sludge again are provided.

  The water treatment apparatus according to claim 5 is the water treatment apparatus according to claim 1, wherein the back pressure valve provided downstream of the first reactor, and the solid-liquid separation provided downstream of the back pressure valve for separating the supernatant into sludge. An apparatus, a second pressure pump for feeding the separated sludge, and a second reactor for heating the pressurized sludge again are provided.

  According to the present invention, in water treatment for removing impurities from sewage, flocculant and magnetic powder are added to the sewage, the generated magnetic flocs are removed by a magnetic floc separator, and the generated sludge is decomposed by hydrothermal treatment. After cooling and decompression, the magnetic powder is recovered from the sludge and the recovered magnetic powder is used again. Therefore, the manufacturing cost can be reduced by setting the pressure resistance and heat resistance of the magnetic separator to normal temperature and normal pressure. By reusing powder, it is possible to provide a water treatment device that reduces waste and reduces running costs.

  In addition, since the sludge is consolidated and moisture is removed before the hydrothermal treatment for decomposing the sludge, the energy required for the hydrothermal treatment can be reduced.

It is the schematic of the structure of the water treatment apparatus which shows an example of this embodiment. It is the schematic of the structure of the water treatment apparatus which shows another example of this embodiment. It is the schematic of the structure of the water treatment apparatus which shows another example of this embodiment. It is the schematic of the structure of the water treatment apparatus which shows another example of this embodiment. It is the schematic of the structure of the water treatment apparatus which shows another example of this embodiment. It is explanatory drawing explaining the saturated vapor pressure curve of water. It is the schematic of the structure of the water treatment which shows an example of this embodiment.

(First embodiment)
FIG. 1 shows an example of a water treatment apparatus provided by the present invention. The water treatment apparatus shown here shows the configuration of a water treatment apparatus using a cohesive magnetic separation system.

  Sewage to be treated water is accumulated in the raw water tank 101. This sewage is sent to the stirring device 103 by the pump 102. In the stirring device 103, the flocculant and the magnetic powder dispersed in water are respectively fed from the flocculant tank 104 and the magnetic powder tank 105, and by stirring these, a magnetic floc composed of the contaminants and the magnetic powder is formed. The When the sewage in which the magnetic floc is formed is sent to the magnetic separation device 106, the magnetic flock is recovered from the sewage to obtain purified water, and the recovered magnetic flock is sent to the sludge tank 1.

  The sludge, which is an assembly of magnetic flocs, is fed by the pump 2 and is preheated by receiving heat from the high temperature sludge after hydrothermal treatment in the heat exchanger 5. Next, the sludge introduced into the reactor 4 is heated by the heater 3 so that the target temperature can be maintained, and decomposed into magnetic powder and other impurities by lowering the function of the flocculant. When the decomposed sludge is discharged from the reactor 4, the heat exchanger 5 performs heat exchange with the low temperature sludge and is cooled to a boiling point or lower at atmospheric pressure. The cooled sludge is depressurized to atmospheric pressure by the back pressure valve 6 and supplied to the magnetic separation device 7. At this time, it is necessary to set the sludge pressure until it is pressurized by the pump 2 and reduced by the back pressure valve 6 to be equal to or higher than the saturated vapor pressure of sludge at the temperature in the reactor 4. The sludge supplied to the magnetic separation device 7 is separated into magnetic powder and the remaining sludge by magnetic force, and the magnetic powder is recovered. The collected magnetic powder is transported to the magnetic powder tank 105 and used again for cohesive magnetic separation.

  Moreover, as the conditions of the above-mentioned hydrothermal treatment, sludge can be decomposed in a short time when heated at 200 ° C. or higher, and at 300 ° C. or higher, the composition change of the magnetic powder proceeds rapidly and the saturation magnetization decreases. The heating temperature is preferably set between 200 ° C and 300 ° C.

  As described above, in the water treatment apparatus of the present invention, the magnetic separation for recovering the magnetic powder after the sludge is decomposed by the hydrothermal treatment at high temperature and high pressure can be performed at room temperature and normal pressure. And heat resistance can be set to normal temperature and pressure, reducing manufacturing costs. Moreover, since the magnetic powder discarded as sludge is efficiently recovered, the amount of generated sludge can be reduced. Furthermore, since the magnetic powder can be reused in the aggregation magnetic separation device, a water treatment device with low running cost can be provided.

  Moreover, the high temperature in this invention refers to the boiling point or more of the sludge under the atmospheric pressure, and the high pressure refers to the atmospheric pressure or more. Furthermore, although one kind of flocculant is used here, the kind of flocculant may be increased as needed, and a neutralizing agent etc. may be added.

(Second Embodiment)
FIG. 2 shows another example of the water treatment apparatus provided by the present invention. The water treatment apparatus shown here performs the decomposition reaction described in the first embodiment in two stages of low temperature and high temperature, and performs the second stage high temperature decomposition reaction by performing solid-liquid separation after the first stage reaction. The device configuration is capable of reducing the amount of sludge to be fed to the tank.

  First, as in the first embodiment, sludge containing magnetic powder generated by purification of sewage is accumulated in the sludge tank 1. This sludge is fed by the pump 2 and is preheated by receiving heat from the high temperature sludge after hydrothermal treatment in the heat exchanger 5. Next, the sludge introduced into the reactor 4 is heated at 150 ° C. or less by the heater 3 to reduce the function of the flocculant, so that the sludge can be more compacted than the untreated sludge. This sludge is sent to the heat exchanger 5 to give and receive heat, and then led to the solid-liquid separator 10 where it is separated into a supernatant and a sludge containing magnetic powder, and the supernatant is discharged through the back pressure valve 16; The sludge receives heat from the high-temperature sludge after hydrothermal treatment in the heat exchanger 15 and is preheated. Next, the sludge introduced into the reactor 14 is heated by the heater 13 so that the target temperature can be maintained, and is decomposed into magnetic powder and other impurities by lowering the function of the flocculant. When the decomposed sludge is discharged from the reactor 14, the heat exchanger 15 exchanges heat with the low temperature sludge, and is cooled to the boiling point or less at atmospheric pressure. The cooled sludge is depressurized to the atmospheric pressure by the back pressure valve 6, and the magnetic powder is recovered by the magnetic separation device 7 and conveyed to the magnetic powder tank 105. At this time, the sludge pressure until it is pressurized by the pump 2 and reduced by the back pressure valve 6 needs to be set to be equal to or higher than the saturated vapor pressure of sludge at the temperature in the reactor 14.

  Further, by setting the temperature of the reactor 4 to about 50 ° C. to 150 ° C., it becomes possible to effectively compact the sludge, and the solid-liquid separator 10 can greatly remove the water in the sludge. become.

  As described above, according to the present invention, the sludge guided to the reactor 14 that is at high temperature and high pressure is concentrated and the amount of treatment can be greatly reduced, so that the input energy required for the heater 13 can be reduced.

  Moreover, since this solid-liquid separator 10 is mainly intended for separation of magnetic powder having a large specific gravity and water, the configuration of the solid-liquid separator 10 includes a gravity sedimentation tank, a cyclone, a centrifuge, and a magnetic separation. An apparatus etc. may be sufficient.

(Third embodiment)
FIG. 3 shows still another example of the water treatment apparatus provided by the present invention. The water treatment apparatus shown here has an apparatus configuration capable of performing the first-stage decomposition reaction temperature described in the second embodiment at the atmospheric pressure or lower than the boiling point.

  First, as in the first embodiment, sludge containing magnetic powder generated by purification of sewage is accumulated in the sludge tank 1. This sludge is fed by the pump 2 and is preheated by receiving heat from the high temperature sludge after hydrothermal treatment in the heat exchanger 5. Next, the sludge introduced into the reactor 4 is heated to a boiling point or lower at atmospheric pressure by the heater 3 to reduce the function of the flocculant so that the sludge can be more compacted. After passing this sludge through the heat exchanger 5, it is guided to the solid-liquid separator 10, where it is separated into sludge containing a supernatant liquid and magnetic powder under atmospheric pressure, and the supernatant liquid is discharged. The sludge separated into solid and liquid is pressurized by the pump 22, and downstream of the reactor 14, the sludge is treated in the same manner as in the second embodiment, and the magnetic powder is collected and conveyed to the magnetic powder tank 105. It is a mechanism.

  The difference from the second embodiment is that the first stage decomposition reaction proceeding in the reactor 4 is carried out under almost atmospheric pressure. According to the water treatment apparatus of the present invention, since the internal pressure of the reactor 4, the heat exchanger 5, and the solid-liquid separator 10 is also almost atmospheric pressure, the pressure resistance performance of these constituent devices can be set to atmospheric pressure, Cost can be reduced.

  Moreover, the generation | occurrence | production ratio of the water and solid in the solid-liquid separator 10 may change with the composition change of to-be-processed sludge. In this case, a sensor that measures the generation ratio of water and solid matter in the solid-liquid separator 10 is installed, and a controller that changes the liquid feeding speed of the pump 22 and the pump 2 and the output of the heater according to the ratio is installed. By doing so, efficient operation can be performed. Furthermore, when the processing speed of the reactor 4 or the reactor 14 is insufficient, the processing speed can be improved by raising the reaction temperature.

(Fourth embodiment)
FIG. 4 shows still another example of the water treatment apparatus provided by the present invention. The water treatment apparatus shown here has an apparatus configuration capable of reducing the pressure of the reactor 4 in which the first stage decomposition reaction described in the second embodiment is performed.

  First, as in the first embodiment, sludge containing magnetic powder generated by purification of sewage is accumulated in the sludge tank 1. This sludge is pressurized by the pump 2 and is preheated by receiving heat from the high temperature sludge after hydrothermal treatment in the heat exchanger 5. Next, the sludge introduced into the reactor 4 is heated at 150 ° C. or less by the heater 3 to reduce the function of the flocculant so that the sludge can be consolidated. This sludge is guided to the solid-liquid separator 10 and separated into a supernatant and a sludge containing magnetic powder, and the supernatant is discharged through the back pressure valve 36. The sludge separated into solid and liquid is further pressurized by the pump 22, and the downstream of the reactor 14 is treated with sludge in the same manner as in the second embodiment, so that the magnetic powder is recovered and stored in the magnetic powder tank 105. It is a mechanism to be transported.

  The difference from the second embodiment is that the first stage decomposition reaction proceeding in the reactor 4 is carried out at a pressure lower than the pressure in the reactor 14.

  The saturated vapor pressure curve of water is shown in FIG. As can be seen from FIG. 6, the saturated vapor pressure of water increases rapidly as the temperature increases, so that the reaction pressure can be greatly reduced if the reaction temperature can be reduced even a little. Therefore, according to the water treatment apparatus of the present invention, the internal pressure of the solid-liquid separator 10 can be set lower than that in the second embodiment, so that the reactor 4, the heat exchanger 5, and the solid-liquid separator 10 can be set. The pressure resistance performance of the apparatus configuration can be set low, and the manufacturing cost can be reduced.

  Moreover, the generation | occurrence | production ratio of the water and solid in the solid-liquid separator 10 may change with the composition change of to-be-processed sludge. In this case, a sensor that measures the generation ratio of water and solid matter in the solid-liquid separator 10 is installed, and a controller that changes the liquid feeding speed of the pump 22 and the pump 2 and the output of the heater according to the ratio is installed. By doing so, efficient operation can be performed. Furthermore, when the processing speed of the reactor 4 or the reactor 14 is insufficient, the processing speed can be improved by raising the reaction temperature.

(Fifth embodiment)
FIG. 5 shows still another example of the water treatment apparatus provided by the present invention. The water treatment apparatus shown here has an apparatus configuration capable of reducing the pressure of sludge flowing through the solid-liquid separator 10 described in the second embodiment.

  First, as in the first embodiment, sludge containing magnetic powder generated by purification of sewage is accumulated in the sludge tank 1. This sludge is pressurized by the pump 2 and is preheated by receiving heat from the high temperature sludge after hydrothermal treatment in the heat exchanger 5. Next, the sludge introduced into the reactor 4 is heated at 150 ° C. or less by the heater 3 to reduce the function of the flocculant so that the sludge can be consolidated. At this time, the pressure in the reactor 4 is maintained at or above the saturated vapor pressure by the back pressure valve 46, and the sludge that has passed through the back pressure valve 46 is guided to the solid-liquid separator 10 at atmospheric pressure. Here, the supernatant liquid is separated into sludge containing magnetic powder, the supernatant liquid is discarded, and the sludge is pressurized again by the pump 22. Downstream of the reactor 14, the sludge is treated and the magnetic powder is collected and transported to the magnetic powder tank 105 as in the second embodiment.

  As an example, the flow of the substance will be described. When polyaluminum chloride and polyacrylamide are used as the flocculant, the stirrer 103 produces magnetic flocs composed of contaminants, magnetic powder, polyaluminum chloride, and polyacrylamide. The magnetic floc is collected by the magnetic separator 106 and accumulated in the sludge tank 1 as sludge. When this sludge is heated at about 150 ° C. and allowed to stand, the solid content in the sludge is consolidated and separated into a supernatant and a solid content. When the supernatant is discarded and the solid content containing a small amount of water is hydrothermally treated in the reactor 14 at 200 ° C. or higher, the solid content is decomposed, so that the magnetic powder can be recovered. By transporting the collected magnetic powder to the magnetic powder tank 105 again, reuse of the magnetic powder and reduction of sludge discharge can be achieved, resulting in a reduction in running cost.

  As described above, according to the water treatment apparatus of the present invention, since the internal pressure of the solid-liquid separator 10 can be made almost atmospheric pressure, the pressure resistance performance of the solid-liquid separator 10 can be set low, and the manufacturing cost can be reduced.

  FIG. 7 shows the constituent elements of the above-described second, third, fourth, and fifth embodiments and the pressure applied to the constituent elements. In FIG. 7, the second embodiment is referred to as Example 2, the third embodiment as Example 3, the fourth embodiment as Example 4, and the fifth embodiment as Example 5. It is shown.

  As can be seen from FIG. 7, in the second embodiment, the pressure from the pump 2 to the back pressure valve 6 is 1 MPa or higher, whereas in the third embodiment, only the pump 22 to the back pressure valve 6 is higher than 1 MPa. . In Example 4 and Example 5, the pressure in the reactor 4 is increased to 1 MPa or less. However, in these examples, the temperature required for compaction of sludge is insufficient at the boiling point of sludge at atmospheric pressure. Used.

DESCRIPTION OF SYMBOLS 1 ... Sludge tank, 2 ... Pump, 3 ... Heater, 4 ... Reactor, 5 ... Heat exchanger, 6 ... Back pressure valve, 7 ... Magnetic separator, 10 ... Solid-liquid separator, 13 ... Heater, 14 ... Reactor 15 ... heat exchanger, 16 ... back pressure valve, 22 ... pump, 36 ... back pressure valve, 46 ... back pressure valve, 101 ... raw water tank, 102 ... pump, 103 ... stirrer, 104 ... flocculant tank, 105 ... magnetic powder Tank, 106 ... Magnetic separation device

Claims (5)

At least one flocculant injection device for injecting the flocculant into the wastewater to be treated;
A magnetic powder injection device for injecting magnetic powder;
At least one stirring device that stirs to form a magnetic floc;
A magnetic floc separating device for separating the generated magnetic floc;
A first pressure pump for feeding sludge, which is an aggregate of separated magnetic flocs,
A first reactor heated by a heater while the pressurized sludge passes through;
A back pressure valve that discharges sludge to atmospheric pressure while maintaining a high pressure in the reactor;
A magnetic separator for recovering magnetic powder from the discharged sludge;
And a transfer device for transferring the recovered magnetic powder to the magnetic powder input device. A solid-liquid separation device provided downstream of the first reactor, for separating into a supernatant and sludge;
A back pressure valve for discharging the supernatant liquid;
The water treatment apparatus according to claim 1, further comprising a second reactor that reheats the separated sludge. A solid-liquid separation device provided downstream of the first reactor, for separating into a supernatant and sludge;
A second pressure pump for feeding separated sludge;
The water treatment apparatus according to claim 1, further comprising a second reactor that reheats the pressurized sludge. A solid-liquid separation device provided downstream of the first reactor, for separating into a supernatant and sludge;
A back pressure valve for discharging the supernatant liquid;
A second pressure pump for feeding separated sludge;
The water treatment apparatus according to claim 1, further comprising a second reactor that reheats the pressurized sludge. A back pressure valve provided downstream of the first reactor;
A solid-liquid separator that is provided downstream of the back pressure valve and separates into supernatant and sludge;
A second pressure pump for feeding separated sludge;
The water treatment apparatus according to claim 1, further comprising a second reactor that reheats the pressurized sludge.

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