JP2014193438A - Method of dehydrating organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of dehydrating organic sludge which can reduce the moisture content of the organic sludge easily without use of a pressure container.SOLUTION: A method of dehydrating organic sludge comprises mixing organic sludge with an organic solvent A which is liquid at ordinary temperature and ordinary pressure and has volatility, supplying the organic sludge B mixed with the organic solvent A to a dehydration portion of a dehydration machine 5 provided with warming means to carry out a dehydration step of dehydrating the organic sludge B while warming the organic sludge B in the dehydration portion to a first specified temperature equal to or higher than the boiling point of the organic solvent A so as to evaporate the organic solvent A mixed with the organic sludge B and discharging the evaporated organic solvent A from the dehydration portion to recover.

Description

  The present invention relates to a method for dewatering organic sludge containing organic substances generated from, for example, sewage and food industry.

  Conventionally, when organic sludge is mechanically squeezed and dehydrated, it is difficult to dehydrate the water in the cell membrane of organic matter in organic sludge (referred to as encapsulated water). It was generally difficult to make it 60 to 80% or less.

  On the other hand, as a method for dewatering organic sludge, for example, as shown in FIG. 10 (a), dimethyl ether, which is a gas at room temperature and normal pressure, is mixed with organic sludge, and this organic sludge is placed in the pressurized container 101. Supply and pressurize the inside of the pressurized container 101 to 0.78 MPa to liquefy dimethyl ether, replace the liquefied dimethyl ether with the water contained in the organic matter in the organic sludge, take out the water in the cell membrane to the outside, and liquefy Incorporated dimethyl ether into the cell membrane.

  Thereafter, as shown in FIG. 10B, the pressure in the pressure vessel 101 is released and returned to room temperature and normal pressure, thereby vaporizing dimethyl ether and recovering the vaporized dimethyl ether, as shown in FIG. 10C. As described above, there is a method in which organic sludge and water are taken out from the pressurized container 101 and solid-liquid separated by the solid-liquid separator 102. By such a method, water in the cell membrane (included water) can be dehydrated, and the moisture content of the organic sludge can be reduced.

  In addition, the above dehydration methods are described in the following patent document 1, for example.

Patent No. 4,291,772

  However, in the above conventional type, dimethyl ether is liquefied by pressurization to replace liquid dimethyl ether and contained water, so that the pressurized container 101 is a first-class pressure container, and safety precautions are taken in manufacturing and handling. In short, there is a problem that the safety management related to the first type pressure vessel is troublesome.

  An object of the present invention is to provide a method for dewatering organic sludge that can easily reduce the moisture content of organic sludge without using a pressure vessel.

To achieve the above object, the organic sludge dewatering method according to the first aspect of the present invention mixes an organic solvent that is liquid and volatile at room temperature and normal pressure with organic sludge,
The organic sludge mixed with the organic solvent is supplied to the dehydrator of the dehydrator equipped with a heating means to perform the dehydration process,
In the dehydration step, the organic sludge in the dehydration part is heated to a first predetermined temperature equal to or higher than the boiling point of the organic solvent to vaporize the organic solvent mixed in the organic sludge,
The vaporized organic solvent is discharged from the dehydration unit and collected.

  According to this, since the cell membrane of organic matter in organic sludge is dissolved and damaged by the organic solvent, it becomes possible to dehydrate the contained water using a dehydrator, and the water content of the organic sludge can be easily reduced. it can. Moreover, since the viscosity of water falls by heating, the dewatering rate and desolvation rate of organic sludge increase. Furthermore, since it is not necessary to pressurize the organic sludge mixed with the organic solvent in the pressure vessel, troublesome safety management related to the first type pressure vessel is not required.

In the method for dewatering organic sludge according to the second invention, the organic solvent has a boiling point lower than that of water,
The first predetermined temperature is higher than the boiling point of the organic solvent and lower than the boiling point of water.

  According to this, in the dehydration step, by heating the organic sludge in the dewatering section to the first predetermined temperature, the organic solvent mixed in the organic sludge is vaporized, but the water in the organic sludge is not vaporized but liquid. It is kept as it is. For this reason, without evaporating water, it can isolate | separate from organic sludge with water as it is, and the energy required for isolation | separation can be reduced.

The organic sludge dewatering method according to the third aspect of the invention starts supplying the organic sludge to the dewatering unit in a state where the dewatering unit of the dehydrator is at a second predetermined temperature lower than the boiling point of the organic solvent.
After the start of supply, the dehydrating unit is heated from the second predetermined temperature to the first predetermined temperature.

  According to this, when the supply of organic sludge to the dewatering part of the dehydrator is started, the dehydration part is at the second predetermined temperature, and therefore the organic solvent mixed with the organic sludge when the supply of organic sludge is started. Can be prevented from bumping. Thereby, it can suppress that an organic solvent vaporizes rapidly, and it can prevent that the vaporized organic solvent generate | occur | produces temporarily in large quantities. Therefore, it is possible to reliably and sufficiently recover the vaporized organic solvent, and it is possible to prevent the vaporized organic solvent from being diffused without being recovered and leaking from the dehydrator to the outside of the dehydrator.

The method for dewatering organic sludge according to the fourth aspect of the invention is to collect the vaporized organic solvent by sucking it out from the dewatering section and returning it from gas to liquid.
According to this, since the organic solvent is recovered by returning from the gas to the liquid, the recovered organic solvent in the liquid can be repeatedly reused as it is.

  As described above, according to the present invention, the moisture content of the organic sludge can be easily reduced without using a pressure vessel, so that troublesome safety management relating to the first type pressure vessel is not required.

It is a figure which shows typically the dehydration system of the organic sludge in the 1st Embodiment of this invention. It is a side view of a filter press used in the dehydration system. It is an exploded perspective view showing the composition of a filter press same as the above. FIG. 3 is a partially enlarged side view of the filter press. It is sectional drawing of the filter plate of a filter press, Comprising: The state which is performing the filtration process is shown. It is sectional drawing of the filter plate of a filter press, Comprising: The state which is performing the pressing process is shown. It is sectional drawing of the filter plate of a filter press, Comprising: The state which is performing the drying process is shown. FIG. 3 is an enlarged cross-sectional view of a sludge injection passage portion of a filter plate of the filter press, showing a state in which the filter plates are opened. FIG. 4 is an enlarged cross-sectional view of a sludge injection passage portion of a filter plate of the filter press, showing a state in which the filter plates are closed. It is a figure which shows the conventional dehydration method of organic sludge.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
In the first embodiment, FIG. 1 is a diagram schematically showing an organic sludge dewatering system 1 in sewage treatment. According to this, the concentration machine 3 which concentrates the organic sludge denitrified in the denitrification tank 2, the mixing tank 4 which mixes the alcohol solvent A into the concentrated organic sludge, and the organic sludge in which the alcohol solvent A is mixed. An endless filter cloth traveling filter press 5 for dehydrating B (an example of a dehydrator), a condenser 6 for returning the vaporized alcohol solvent A to a liquid, and a liquid alcohol system from the filtrate taken out of the filter press 5 And a heating still 7 for separating and recovering the solvent A.

  The alcohol solvent A is an example of a volatile organic solvent that is liquid under normal temperature and normal pressure (25 ° C., 1 atm), and methanol and ethanol are used as specific examples. The alcohol solvent A has a boiling point lower than that of water (100 ° C.), for example, 65 ° C. for methanol and 78 ° C. for ethanol. Here, the boiling point means a standard boiling point at 1 atm.

For the concentrator 3, for example, a belt concentrator is used. The mixing tank 4 is equipped with a stirrer for stirring and mixing the organic sludge and the alcohol solvent A.
As shown in FIG. 2, the filter press 5 includes a fixed frame 15, a movable frame 16 that can be moved toward and away from the fixed frame 15, and a plurality of frames that are arranged between the frames 15 and 16 so as to be moved toward and away from each other. A filter plate 17, an endless filter cloth 18, an opening / closing device 19 that opens and closes the filter plates 17 by moving the filter plates 17 close to each other, a filter cloth drive device 29 that causes the filter cloth 18 to travel in one direction D, Heating means 20. As shown in FIG. 3, the filter cloth 18 is stretched around a roller 21 and arranged in an inverted U shape between the filter plates 17. Between each filter plate 17, a filter chamber 22 (an example of a dewatering unit) is formed between a pair of filter cloths 18 facing each other. The opening / closing device 19 has a cylinder 23 for moving the movable frame 16.

  As shown in FIG. 4, the fixed frame 15 and the filter plate 17 at one end are connected by a link 24, and similarly, the movable frame 16 and the filter plate 17 at the other end are connected by a link 25. 17 are connected by a link mechanism 26.

  As shown in FIGS. 5 to 7, each filter plate 17 is formed with a recess 27 that opens on one side of the front and back surfaces, and a diaphragm 28 is provided in the recess 27. Further, each filter plate 17 is connected with a first hot water supply path 30 that supplies hot water 10 to expand the diaphragm 28 and a first hot water discharge path 31 that discharges the hot water 10 and contracts the diaphragm 28. Has been.

  Further, each filter plate 17 is formed with a warming passage 32 through which the hot water 11 flows, a second hot water supply passage 33 for supplying the warm water 11 to the warming passage 32, and the warm water 11 from the warming passage 32. A second hot water discharge path 34 for discharging is connected. The heating means 20 includes first and second hot water supply paths 30 and 33, first and second hot water discharge paths 31 and 34, and a heating path 32.

  The first and second hot water supply paths 30 and 33 and the first and second hot water discharge paths 31 and 34 have been described as separate paths. It is possible to unify the first and second hot water discharge paths 31 and 34 into one path.

  As shown in FIGS. 3, 4, 8 and 9, each filter plate 17 is formed with a sludge injection passage 36 for injecting organic sludge B into the filter chamber 22. Further, between the filter plates 17, a base member 37 (feed piece) is supported by the link mechanism 26. Each base member 37 is formed with a branch passage 38 branched from the sludge injection passage 36 and leading to the filter chamber 22.

  Each filter plate 17 is formed with a filtrate discharge passage 40 (see FIG. 3) for discharging the filtrate C generated from the organic sludge B squeezed in the filter chamber 22. As shown in FIGS. 8 and 9, the fixed frame 15 has a sludge inlet 41 communicating with the sludge inlet passage 36 of the adjacent filter plate 17 and a filtrate outlet (not shown) communicating with the filtrate outlet passage 40. ) And are formed. The movable frame 16 is formed with a recovery fluid injection port 43 communicating with the sludge injection passage 36 of the adjacent filter plate 17.

  As shown in FIGS. 1, 2, 4, and 9, the sludge that supplies the organic sludge B in the mixing tank 4 to the filter press 5 between the mixing tank 4 and the sludge inlet 41 of the filter press 5. A supply path 45 is connected. The sludge supply path 45 is composed of piping or the like, and a sludge supply pump 46 and a sludge supply valve 47 are provided in the middle. The sludge supply path 45 includes a first return path 48 branched from the sludge supply path 45 and communicated with the mixing tank 4, and a second return path 49 branched from the sludge supply path 45 and communicated with the denitrification tank 2. Is connected. The first and second return paths 48 and 49 are provided with first and second return valves 50 and 51, respectively.

  A recovery fluid supply path 44 that supplies compressed air 12 (an example of a recovery fluid) is connected to the recovery fluid inlet 43 of the filter press 5. The recovery fluid supply path 44 is provided with a recovery fluid supply valve 52 and a recovery fluid supply source 53 including a compressor.

  As shown in FIG. 1, a filtrate recovery path 54 is connected between the filtrate outlet of the filter press 5 and the heating distiller 7 to send the filtrate C discharged from the filter press 5 to the heating distiller 7. ing. The filtrate collection path 54 is provided with a filtrate collection valve 55. Further, the filtrate recovery path 54 joins the first solvent recovery path 56 a branched from the filtrate recovery path 54 and communicated with the inlet of the condenser 6 and the filtrate recovery path 54 from the outlet of the condenser 6. A two-solvent recovery path 56b is connected. A solvent recovery valve 57 is provided in the first solvent recovery path 56a.

  Between the mixing tank 4 and the heating distiller 7, a first solvent return path 58 for returning the liquid alcohol solvent A separated and recovered from the filtrate C in the heating distiller 7 to the mixing tank 4 is provided. Yes. Further, a second solvent return path 59 for returning the liquid alcohol solvent A to the denitrification tank 2 is provided between the denitrification tank 2 and the heating distiller 7. The second solvent return path 59 is branched from the first solvent return path 58, and the first and second solvent return paths 58 and 59 are provided with first and second return valves 60 and 61, respectively.

Hereinafter, the operation of the above configuration will be described.
A method for dewatering organic sludge using the dehydration system 1 will be described below.
In advance, the cylinder 23 of the opening / closing device 19 of the filter press 5 is actuated to bring the movable frame 16 closer to the fixed frame 15, and the filter plates 17 are closed as shown in FIGS. . Further, the hot water 11 is supplied from the second hot water supply path 33 to the heating passage 32 of each filter plate 17, discharged from the heating passage 32 to the second hot water discharge path 34, and passed through the heating passage 32. While maintaining the water condition, the inside of the filter chamber 22 is heated to the first predetermined temperature by the hot water 11 in the heating passage 32.

  The first predetermined temperature is a temperature not lower than the boiling point of the alcohol solvent A and lower than the boiling point of water. For example, when the alcohol solvent A is methanol, the first predetermined temperature is not lower than 65 ° C. and lower than 100 ° C. In the case of ethanol, the first predetermined temperature is 78 ° C. or higher and lower than 100 ° C.

  1, the sludge supply valve 47, the filtrate recovery valve 55, and the first return valve 60 are opened, and the first and second return valves 50 and 51 and the recovery fluid supply valve 52 are opened. And the solvent recovery valve 57 and the second return valve 61 are closed, the organic sludge denitrified in the denitrification tank 2 is concentrated by the concentrator 3, and in the mixing tank 4, a liquid alcohol system is added to the concentrated organic sludge. Mix solvent A. At this time, if the recovered alcohol solvent A is insufficient, a new alcohol solvent A is used. Thereafter, by driving the sludge supply pump 46, the organic sludge B mixed with the alcohol solvent A is supplied from the mixing tank 4 through the sludge supply path 45 to the filter press 5, and the following filtration process is performed. It dehydrates by the dehydration process which consists of a pressing process and a drying process.

  That is, in the filtration step, as shown in FIG. 9, the organic sludge B passes through the sludge supply passage 45, passes through the sludge injection passages 41 of the filter plates 17 from the sludge injection ports 41 of the filter press 5, and the sludge injection passages 36. And then into the filter chambers 22 through the branch passages 38 of the cap members 37. Thereby, as shown in FIG. 5, the organic sludge B is filtered in each filter chamber 22. At this time, since the filter chamber 22 is heated to the first predetermined temperature by the hot water 11 passing through the heating passage 32, the organic sludge B injected into the filter chamber 22 is also heated to the first predetermined temperature. .

  After performing the filtration step, as shown in FIG. 6, the hot water 10 is supplied from the first hot water supply path 30 to each filter plate 17 and continues to pass through the inner space 13 of the diaphragm 28. Thereby, the diaphragm 28 expand | swells and the organic sludge B in the filter chamber 22 is squeezed and dehydrated. Even when such a pressing process is performed, the organic sludge B in the filter chamber 22 is heated to the first predetermined temperature by continuously passing the hot water 11 through the heating passage 32. That is, the organic sludge B continues to be heated to the first predetermined temperature while remaining in the filter chamber 22.

  The filtrate C generated in the filtration step and the squeezing step passes through the filtrate discharge passage 40 of each filter plate 17 and is discharged from the filtrate discharge port. As shown in FIG. It is sent to the heating still 7. The filtrate C contains water and a liquid alcohol solvent A.

  Furthermore, after performing the said pressing process, as shown in FIG. 7, the hot water 10 to the inner side space 13 of the diaphragm 28 from the 1st hot water supply path 30 in the state which passed the warm water 11 through the heating channel | path 32 continuously. The hot water 10 in the inner space 13 of the diaphragm 28 is discharged to the first hot water discharge path 31 to empty the inner space 13. Thereby, the diaphragm 28 contracts and is separated from the filter cloth 18, and a drying space 14 is formed between the diaphragm 28 and the filter cloth 18. At this time, since the organic sludge B in the filter chamber 22 is heated to the first predetermined temperature by the hot water 11 in the heating passage 32, the alcohol solvent A mixed in the organic sludge B is vaporized and dried. It is taken out into the space 14.

  The vaporized alcohol solvent A is mainly recovered in the drying step as described above. However, it can be recovered by suction in the filtration step and the pressing step, and the recovery efficiency is further improved.

  When performing such a drying step, as shown in FIG. 1, the filtrate recovery valve 55 is closed and the solvent recovery valve 57 is opened, and the vaporized alcohol solvent A is exhausted (not shown) or the like. Aspirate and discharge from the filter chamber 22. As a result, the evaporated alcoholic solvent A passes through the filtrate discharge passage 40 from the drying space 14 of each filter plate 17, is discharged from the filtrate discharge port of the filter press 5, and is branched from the filtrate collection path 54. It passes through the first solvent recovery path 56 a and is supplied to the condenser 6. The alcohol-based solvent A supplied to the condenser 6 in this way is condensed from gas to liquid, and then merged into the filtrate recovery path 54 through the second solvent recovery path 56b and sent to the heating still 7. .

  The filtrate C discharged from the filter press 5 in the filtration step and the squeezing step, and the liquid alcohol solvent A obtained by condensing in the condenser 6 after being discharged from the filter press 5 in the drying step are heated. It is collected in the still 7 and distilled together. As a result, the filtrate C is separated into water and a liquid alcohol solvent A, and the liquid alcohol solvent A is recovered and passed from the heating distiller 7 to the mixing tank 4 through the first solvent return path 58. Will be returned.

  In addition, after the drying process is performed by the filter press 5 as shown in FIG. 6, the sludge supply valve 47 and the second return valve are continuously closed as shown in FIG. 51, the filtrate recovery valve 55 and the solvent recovery valve 57 are closed, the first return valve 50 and the recovery fluid supply valve 52 are opened, and the compressed air 12 is transferred from the recovery fluid supply source 53 to the filter press 5. Supply. At this time, as shown in FIGS. 1 and 9, the compressed air 12 passes from the recovery fluid supply source 53 through the recovery fluid supply path 44, and from the recovery fluid inlet 43 to the sludge injection passage 36 of each filter plate 17. The sludge inlet 41 is passed through, the sludge inlet 41 is backflowed through the sludge supply path 45, the branch flows from the sludge supply path 45 to the first return path 48, and is discharged to the mixing tank 4.

  Thereafter, the cylinder 23 of the opening / closing device 19 of the filter press 5 is actuated to separate the movable frame 16 from the fixed frame 15 and open between the filter plates 17 as shown in FIGS. Then, the filter cloth drive device 29 causes the filter cloth 18 to travel in one direction D, and the dewatered cake 63 is discharged downward from the filter chamber 22 between the filter cloths 18.

  In the organic sludge dehydration method as described above, as shown in FIG. 1, by mixing a liquid alcohol-based solvent A with the organic sludge in the mixing tank 4, the organic cell membrane in the organic sludge becomes an alcohol-based solvent A. Therefore, the inclusion water can be dehydrated by the pressure dehydration in the filter press 5, and the moisture content of the organic sludge can be easily reduced.

  Moreover, as shown in FIGS. 5-7, since the viscosity of water falls by heating the organic sludge B in the filter chamber 22 of the filter press 5 to 1st predetermined temperature, the dehydration rate of the organic sludge B And the solvent removal rate is increased. Furthermore, since the alcohol solvent A is a liquid at normal temperature, there is no need to pressurize the organic sludge B mixed with the alcohol solvent A in the pressurization vessel, and this relates to the first type pressure vessel for pressurization. Troublesome safety management becomes unnecessary.

  Moreover, as shown in FIG. 7, in the drying process of the filter press 5, since the organic sludge B in the filter chamber 22 is heated to the first predetermined temperature, it is mixed with the organic sludge B in the filter chamber 22. The alcohol solvent A is vaporized, but the water in the organic sludge B is not vaporized and is kept in a liquid state. For this reason, without evaporating water, water can be separated from the organic sludge B in a liquid state, and energy required for the separation can be reduced.

  The evaporated alcoholic solvent A is taken out from the filter press 5 and returned to a liquid, and then returned to the mixing tank 4. That is, the alcohol solvent A can be repeatedly reused as it is.

  Further, as shown in FIG. 1, the compressed air 12 flows from the filter press 5 through the sludge supply path 45 and the first return path 48 to the mixing tank 4, thereby remaining the organic sludge remaining in the sludge supply path 45. B is returned to the mixing tank 4 through the first return path 48 along with the flow of the compressed air 12. Thereby, since the alcoholic solvent A mixed in the returned organic sludge B is also returned to the mixing tank 4, the alcoholic solvent A remaining in the sludge supply path 45 can be recovered and reused. it can. From this, the amount of the alcohol solvent A that is newly added to the mixing tank 4 and used can be reduced.

  In the first embodiment, by setting the first predetermined temperature to a value slightly higher than the boiling point of the alcohol solvent A, it is possible to suppress bumping of the alcohol solvent A and water evaporation, which is preferable. It is.

  In the first embodiment, as shown in FIG. 1, the first and second return paths 48 and 49 and the first and second solvent return paths 58 and 59 are provided. , 58, 59 are not required, and at least one of these paths 48, 49, 58, 59 is sufficient.

(Second Embodiment)
In the said 1st Embodiment, the organic sludge in the state which heated beforehand the filter chamber 22 of the filter press 5 to the 1st predetermined temperature (namely, the temperature more than the boiling point of alcohol solvent A and less than the boiling point of water). Although B is injected into the filter chamber 22, in the second embodiment described below, the organic sludge B is heated in a state where the filter chamber 22 is heated to a second predetermined temperature lower than the boiling point of the alcohol solvent A. Is started to be injected into the filter chamber 22, and after the start of injection, the filter chamber 22 is heated from the second predetermined temperature to the first predetermined temperature.

  That is, the hot water 11 having the second predetermined temperature is kept flowing through the heating passage 32 (see FIG. 5) of the filter press 5 in advance, and the inside of the filter chamber 22 is kept in the filter chamber 22 by the hot water 11 in the heating passage 32. 2 Warm to a predetermined temperature. In this state, the organic sludge B is started to be injected into the filter chamber 22, and after the start of injection, the hot water 11 is continuously passed through the heating passage 32 while being heated from the second predetermined temperature to the first predetermined temperature. 22 is heated from the second predetermined temperature to the first predetermined temperature.

  In addition, although the timing which heats the filter chamber 22 from 2nd predetermined temperature to 1st predetermined temperature as mentioned above is performed in the middle of the filtration process of the filter press 5 shown in FIG. 5, the pressing process shown in FIG. You may carry out in the inside or the drying process shown in FIG. The second predetermined temperature is, for example, set to 60 ° C. when the alcohol solvent A is methanol, and 73 ° C. when the alcohol solvent is ethanol, but is not limited to these temperatures as long as it is lower than the boiling point. Absent.

Hereinafter, the operation of the above configuration will be described.
When the injection of the organic sludge B into the filter chamber 22 is started, the filter chamber 22 is at the second predetermined temperature. Therefore, the alcohol-based solvent A mixed in the organic sludge B is started when the injection of the organic sludge B is started. Can be prevented from bumping. Thereby, it can suppress that the alcoholic solvent A vaporizes rapidly, and it can prevent that the vaporized alcoholic solvent A generate | occur | produces temporarily and excessively in large quantities. Accordingly, the vaporized alcohol solvent A can be reliably and sufficiently condensed in the condenser 6 and returned to the liquid to be recovered, and the vaporized alcohol solvent A can be recovered without being recovered and filtered from the filter chamber 22. Leakage to the outside of the press 5 can be prevented.

(Third embodiment)
In the first embodiment, after the dehydration process is performed by the filter press 5, the compressed air 12 is supplied from the recovery fluid supply source 53 to the filter press 5 and discharged to the mixing tank 4. In the third embodiment to be described, after the dehydration process is performed by the filter press 5, the compressed air 12 is supplied from the recovery fluid supply source 53 to the filter press 5 and discharged to the denitrification tank 2.

  That is, as shown in FIG. 1, the sludge supply valve 47, the first return valve 50, the filtrate recovery valve 55, and the solvent recovery valve 57 are connected with the filter plates 17 of the filter press 5 closed. The second return valve 51 and the recovery fluid supply valve 52 are opened, and the compressed air 12 is supplied from the recovery fluid supply source 53 to the filter press 5. At this time, the compressed air 12 passes from the recovery fluid supply source 53 through the recovery fluid supply path 44 and reaches the sludge injection port 41 from the recovery fluid injection port 43 through the sludge injection passage 36 of each filter plate 17 (FIG. 9), the sludge supply path 45 flows backward from the sludge inlet 41, flows from the sludge supply path 45 to the second return path 49, and is discharged to the denitrification tank 2.

  Thus, the organic sludge B remaining in the sludge supply path 45 is returned to the denitrification tank 2 through the second return path 49 along with the flow of the compressed air 12. Accordingly, the alcoholic solvent A mixed in the returned organic sludge B is also supplied to the denitrification tank 2, and the alcoholic solvent A becomes a nutrient source for the denitrifying bacteria in the denitrification tank 2, so that the alcoholic solvent A is used. It can be used effectively without waste.

(Fourth embodiment)
In the first embodiment, the liquid alcohol solvent A is returned from the heating distiller 7 to the mixing tank 4 through the first solvent return path 58, but in the fourth embodiment described below. The liquid alcohol solvent A is supplied from the heating distiller 7 to the denitrification tank 2 through the second solvent return path 59.

  That is, as shown in FIG. 1, by closing the first return valve 60 and opening the second return valve 61, the liquid alcohol-based solvent A passes through the second solvent return path 59 from the heating distiller 7. And supplied to the denitrification tank 2. Thereby, the alcoholic solvent A becomes a nutrient source for the denitrifying bacteria in the denitrifying tank 2, and the alcoholic solvent A can be effectively used without being wasted.

In each of the above embodiments, the filter press 5 is used as an example of a dehydrator. However, as another example, a screw press or a belt press may be used.
In each of the above embodiments, the alcohol solvent A is used as an example of the organic solvent, but acetone or hexane may be used.

  In each of the above embodiments, as shown in FIG. 6, the heating means 20 for heating using the warm water 10, 11 has been described. However, in place of the warm water 10, 11, other than warmed oil, air, etc. These fluids may be used. Also, other types of heating means that do not use fluid, such as an electric heater, may be used.

  In each of the above embodiments, as shown in FIG. 1, the compressed air 12 is supplied to the sludge supply path 45 via the filter press 5, but not via the filter press 5, and the sludge inlet of the filter press 5. The sludge supply path 45 may be directly supplied from the 41 side, only the sludge supply path 45 may be washed, and the organic sludge B remaining in the sludge supply path 45 may be recovered.

In each of the above embodiments, the compressed air 12 is used as an example of the recovery fluid, but water, an organic solvent, or the like may be used.
In each said embodiment, although the operation | work which reversely flows the solvent containing organic sludge B which remains in the sludge supply path | route 45 grade | etc., Is performed after the drying process by the filter press 5, each filter plate of the filter press 5 is carried out as a separate process. 17 may be closed.

  In each of the above embodiments, the vaporized alcohol solvent A is returned to a liquid by the condenser 6, but the alcohol solvent A may be returned to the mixing tank 4 or the denitrification tank 2 while remaining in a gas state. However, returning in the liquid state is more convenient because the amount of the alcohol solvent A can be easily controlled.

  In each of the above embodiments, the liquid alcohol solvent A is separated from the filtrate using the heating distiller 7, but other types of equipment capable of separating water and alcohol, such as a vacuum distiller, are used. May be.

5 Filter press (dehydrator)
20 Heating means 22 Filter room (dehydration part)
A Alcohol solvent (organic solvent)
B Organic sludge

Claims (4)

Mix organic solvent that is liquid and volatile at room temperature and normal pressure with organic sludge,
The organic sludge mixed with the organic solvent is supplied to the dehydrator of the dehydrator equipped with a heating means to perform the dehydration process,
In the dehydration step, the organic sludge in the dehydration part is heated to a first predetermined temperature equal to or higher than the boiling point of the organic solvent to vaporize the organic solvent mixed in the organic sludge,
A method for dewatering organic sludge, characterized in that the vaporized organic solvent is discharged from the dewatering section and recovered. The organic solvent has a boiling point lower than that of water,
2. The organic sludge dewatering method according to claim 1, wherein the first predetermined temperature is not lower than the boiling point of the organic solvent and lower than the boiling point of water. In a state where the dehydrating part of the dehydrator is at a second predetermined temperature lower than the boiling point of the organic solvent, supply of organic sludge to the dehydrating part is started.
The method for dewatering organic sludge according to claim 1 or 2, wherein the dewatering section is heated from the second predetermined temperature to the first predetermined temperature after the supply is started. The method for dewatering organic sludge according to any one of claims 1 to 3, wherein the vaporized organic solvent is sucked and discharged from the dewatering section, and is recovered by returning from the gas to the liquid.

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