JP4180722B2 - Waste water treatment method and waste water treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method and apparatus for treating domestic wastewater including raw garbage, and more specifically, a novel wastewater treatment method and wastewater treatment in which concentrated sludge obtained by concentrating wastewater is freeze-dehydrated to form a dehydrated cake and then used as a solid fuel. device, and garbage by lyophilization achieve recycling energy saving relates to wastewater treatment apparatus of garbage pollution-free.
[0002]
[Prior art]
Generally, dehydration and pre-drying are performed as pretreatment for sewage sludge treatment. For the dehydration, a mechanical dehydrator such as a vacuum dehydrator, a screw press dehydrator, or a centrifugal dehydrator is used. Since the moisture content of the dehydrated cake obtained by such mechanical dehydration is limited, in order to reduce the moisture content, a drying process having a dryer is performed to obtain a dried cake. A conventional dryer is of a heating system that heats a dehydrated cake to evaporate moisture. The dried cake obtained through the drying process is sent to an incinerator for incineration.
[0003]
[Problems to be solved by the invention]
A conventional drying method using a heating method consumes a large amount of energy and incinerates the dried cake in an incinerator, which causes pollution such as dioxins and odors.
In addition, a method is also adopted in which sludge cakes separated from wastewater are used for landfill on the ocean, land, etc., but this method not only consumes a lot of energy to produce sludge cake, but also landfill. There is a problem that enormous energy is consumed for transportation to the ground.
[0004]
Also, in the treatment of raw garbage, conventionally, it is treated in an incinerator with a large amount of moisture, or disposed as landfill. Therefore, a great deal of energy and CO2 are generated for transportation to a predetermined treatment area while containing a large amount of water. There is a problem of generating environmental pollutant gases including the like.
[0005]
The present invention has been made paying attention to the above points, and efficiently removes water from sludge by freeze dehydration, and finally makes it a solid fuel that can be reused as an energy resource. and providing a device, in which energy saving can be separated by causing a phase change of water at low energy, to provide a wastewater treatment apparatus of garbage pollution-free type for the purpose.
[0006]
[Means for Solving the Problems]
In order to solve this problem, the invention according to claim 1 is a wastewater treatment method for separating sludge from wastewater containing solids and treating it as a sludge cake.
The step of sending the waste water to a sedimentation tank to produce concentrated sludge, the step of freeze-drying the concentrated sludge to separate water and solids, and the dewatering of the dried cake produced in the freeze-dehydration step generating a dehydrated cake Te, the dehydrated cake was solidified Ri Do and a step of generating a solid fuel product, clarified supernatant drainage separated in the previous SL sedimentation tank is sent to ice machine drainage freezing separator It is characterized in that water obtained by separating the ice into concentrated water and concentrated waste water and dissolving the ice in a heat storage tank is used as intermediate water.
[0007]
The concentrated sludge obtained from the drainage is frozen so that the retained water crystallizes into icicles and destroys the fiber layer, and then thawed and thawed to drip the retained water such as raw garbage in the concentrated sludge. Remove and dry.
By the above operation, a dried cake-like product having an extremely low moisture content is obtained. The dried cake can be dehydrated to obtain a dehydrated cake, which can be reused as an energy resource as a solid fuel.
[0008]
[0009]
In the freeze dehydration step in which the concentrated sludge is lyophilized to separate moisture and solids, the freeze and thaw may be repeated to sufficiently dehydrate the concentrated sludge.
[0010]
The invention of claim 3, wherein the initial settling tank and a sedimentation tank consisting final sedimentation tank effluent, and the concentrated sludge tank for storing concentrated sludge obtained in the initial precipitation tank, concentrated from the concentrated sludge tank Freezing and dehydrating sludge to separate moisture and solids to produce a dried cake, a freeze dehydrating device, a centrifuge for dehydrating the dried cake to produce a dehydrated cake, and the dehydrated cake A pelletizing device for converting to solid fuel; and a drainage freezing and separating device for neutralizing the supernatant wastewater obtained in the final settling tank. The drainage freezing and separating device includes a refrigerator, an ice making machine, and a heat storage tank. has, by freezing the supernatant waste water from the final sedimentation tank is sent to the ice machine, it is separated into concentrated and clear water (ice) drainage, with its ice is sent to the heat storage tank, concentrated Wastewater is passed through the heat exchanger to the initial settling tank Characterized by being configured to be sent.
[0011]
The freeze dehydration apparatus includes a freezing chamber in which an evaporator connected to a heat pump is installed, a melting chamber in which a condenser connected to the heat pump is installed, and the concentrated sludge placed on the freezing chamber from the freezing chamber to the melting chamber. The thing of the structure which consists of a turntable to transfer is used.
[0012]
And the said freeze dehydration apparatus is good also as a structure which enables freezing and thawing | decompression operation of the said concentrated sludge containing fine garbage by intermittent operation of the said turntable.
[0013]
Also, by the garbage that pulverizng a low temperature slow freezing provides a mechanical destruction by generating ice crystals in tissue structures directly with the cell, resulting disruption of the cell membrane, to induce extracellular migration of intracellular held water, followed By the combination of the thawing operation and mechanical dehydration performed, the wastewater is more efficiently dehydrated and the garbage is drained and dried .
[0014]
In wastewater upper Kisei dust, to a low temperature slow freezing while pulverizing the garbage, garbage is placed in extracellular freezing conditions, the cell gap in the organization to produce growth of ice crystals, cells of the tissue Mechanical destruction is directly applied to the structure, the cell membrane is destroyed, and the water retained in the cell is transferred out of the cell.
Therefore, since the cell membrane is destroyed even after being thawed and thawed and returned to the old state, the retained water is not returned to the cell, so that it can be efficiently dehydrated by the subsequent mechanical dehydration.
[0015]
Also, the upper Symbol cold slow freezing to perform substantially 5 ° C. in the following low temperature, thereby enabling large ice crystals formed out of the cells, in which cells to receive unrepairable mechanical disruption.
[0016]
Also, by performing freezing and thawing is repeated a plurality of times, it is also possible to perform a more complete dehydration.
Also, by cold air drying in the subsequent stage of freezing thawing but it may also be to raise the drying effect.
[0017]
Therefore, the wastewater treatment equipment for garbage is composed of a garbage crusher, a movable spreader that spreads the crushed garbage on a perforated receiving plate, and the perforated receiving plate and the crushed garbage that is sprinkled on the perforated receiving plate. A freeze-drying chamber containing a pressure roller that dehydrates by heat treatment of freezing, thawing, and cold air drying; a refrigeration cycle that forms a heat source for freezing, thawing, and cold air; and a dehydration tank provided below the receiving plate It is characterized by comprising more.
[0018]
Freeze drying chamber for the waste water treatment apparatus of the above Kisei garbage, a configuration of providing at least two, by switching the supply of heat from the refrigeration cycle may be alternately performed a plurality of times constituting the operation of freezing and thawing and dehydration.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be exemplarily described below with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the structural parts described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.
It is just an illustrative example.
FIG. 1 is a system diagram showing an embodiment of the waste water treatment apparatus of the present invention, FIG. 2 is a schematic diagram of a main part of FIG. 1, and FIG. 3 is an explanatory diagram showing an example of the freeze dehydration apparatus of FIG. FIG. 4 is a schematic diagram showing a schematic configuration of the wastewater wastewater treatment apparatus of the present invention.
[0020]
In FIG. 1 and FIG. 2, the domestic wastewater 2 coming out of the residential area 1 is sent to the waste resource recycling apparatus 4 through the pipeline 3. The waste resource recycling apparatus 4 includes an initial sedimentation tank 5, a final sedimentation tank 6, an aeration tank 7, a concentrated sludge tank 8, a freeze dehydration apparatus 9, a centrifuge 10, and a pelletization apparatus 11.
The waste water 2 is sent to the initial sedimentation tank 5, and the concentrated sludge settled here is sent to the concentrated sludge tank 8, and the supernatant waste water is sent to the aeration tank 7 and aerated, and the supernatant waste water is the final sedimentation tank 6. Sent to. The concentrated sludge precipitated in the final sedimentation tank 6 is also sent to the concentrated sludge tank 8, and the supernatant drainage is sent to the drainage freezing and separating device 25 to be hydrated (described later).
[0021]
The concentrated sludge concentrated in the concentrated sludge tank 8 is sent to the freeze dehydration apparatus 9 for freeze dehydration.
Various methods are known for the freeze dehydration method. In the present invention, the concentrated sludge is frozen with a freezer (the freezing method in which the water retained in the concentrated sludge is crystallized into ice columns and crystal growth is performed to destroy the fiber layer). ), And then melted and drip-removed the retained water such as raw garbage in the concentrated sludge, followed by drying. Repeat the above operation several times as necessary.
[0022]
The dried cake-like material to be dried, which has been freeze-dehydrated by the freeze-dehydration apparatus 9 and removed to a moisture content of 50% or less, preferably about 20%, is sent to the centrifuge 10. The flocculant 37 is fed into the centrifuge 10 and stirred together with the dried cake to produce a dehydrated solid dehydrated cake. This dehydrated cake is sent to the pelletizing apparatus 11. The pelletizing apparatus 11 is supplied with lime from the lime supply tank 36, and dehydrated cake is solidified together with waste such as combustible garbage, rubber, plastic, etc. from the pit 35 to produce a solid fuel product (RDF) 12. The
[0023]
The separated waste water separated by the centrifugal separator 10 is sent again to the initial settling tank 5 through the pipe line 38 and the above operation is repeated.
The freeze dehydration method is generally a method in which moisture is sublimated and removed and dried in a frozen state, and various methods have been developed. In the present invention, a well-known freeze dehydration method is used. May be used.
[0024]
FIG. 3 shows an example of a freeze dehydration apparatus used in the present invention. A turntable 18 that is intermittently rotated by a driving device 17 is provided in a container 16 having a freezing chamber 14 and a melting chamber 15. An evaporator 20 connected to a heat pump 19 is installed in the freezer compartment 14, and a condenser 21 connected to the heat pump 19 is installed in the melting chamber 15.
[0025]
The concentrated sludge 13 from the concentrated sludge tank 8 is sent to the turntable 18, and after the evaporator 20 absorbs heat and freezes the concentrated sludge 13, it is transferred to the melting chamber 15 by the rotation of the turntable 18. The heat pump 19 obtains heat from a heat source in the freezer compartment 14 and dissipates heat in the melting chamber 15 by the condenser 21, and melts the sent frozen concentrated sludge to remove drip. This drip is sent to the initial settling tank 5 as separated waste water.
[0026]
The dried cake that has been freeze-dehydrated is sent to the centrifuge 10 from the pipe line 22 and is completely dehydrated here to form a dehydrated cake as described above, and then sent to the pelletizing device 11 where it is sent to the pelletizing device 11. Solidified fuel product (RDF) 12 is obtained by solidification.
[0027]
The supernatant wastewater obtained in the final sedimentation tank 6 is sent to the drainage freeze separator 25 and subjected to the middle water treatment. That is, the drainage freezing / separating apparatus 25 has a refrigerator 26 and an ice making machine 27, and the supernatant drainage (including minute solid components) is sent to the ice making machine 27 and frozen, thereby clear water (ice). The ice is sent to the heat storage tank 28, and the concentrated waste water is returned to the initial settling tank 5 through the heat exchanger 32.
[0028]
The ice melted in the heat storage tank 28 is stored as intermediate water 29, and the intermediate water 29 is sent to the residential area 1 and used as it is, or sent to the park 30 for watering plants. And then released into the river. Moreover, it can also utilize in the residential area 1 as purified water by letting the water purification apparatus 31 pass.
[0029]
The ice water in the heat storage tank 28 is sent to the heat exchanger 33. The air cooled by the heat exchangers 32 and 33 is used for cooling the residential district 1, the factory, the shopping mall 34, and the like.
In general, in order to reduce the moisture content of a solid substance to 50% or less, it is necessary to take out the moisture contained in the cells of the solid substance. When this water removal is performed by the freeze dehydration method, the moisture content in the cells is converted into large single crystal ice by freezing, and the water content of 50% or less can be obtained by thawing the ice.
[0030]
[Experimental example]
A concentrated sludge having a moisture content of 14.340 m ³ (water content 99% = 14.197 m ³ ) is placed in the freeze dehydration apparatus 9 and freeze-dehydrated to freeze and thaw the moisture, and the melted moisture 14.161 m ³ Was returned to the initial settling tank 5 as return water. The obtained dried cake-like product was 0.179 m ³ (water content 20% = 0.036 m ³ ). The power consumption required for this was 47 kw × 10 hours. Therefore, the running cost was 47 kW × 10 hours × 5 yen = 2,370 [yen / day].
[0031]
[Comparative Example]
Similarly, 14.340 m ³ (water content 99% = 14.197 m ³ ) of concentrated sludge was placed in a heating evaporation drying apparatus and dried by heating. Steam was used as the heat source for drying, and city gas (rate = 40 yen / Nm ³ ) was used as the fuel. Similarly, the separated water was 14.161 m ³ , and a dried cake of 0.179 m ³ (water content 20% = 0.036 m ³ ) was obtained. The gas consumption required for this was 878 Nm ³ . Therefore, the running cost was 878 Nm ³ × 40 yen = 35,120 [yen / day].
[0032]
As is clear from the above experimental examples and comparative examples, the freeze dehydration method of the present invention requires less energy for drying than the conventional heat evaporation drying method, and the running cost is significantly reduced. Moreover, since the odor is confined in the drip and the odor of garbage is not produced unlike the conventional heating method, it is hygienic.
[0033]
FIG. 4 shows the schematic configuration of the wastewater treatment apparatus for garbage of the present invention. In the figure, reference numerals 30a and 30b denote heat treatment chambers for alternately performing the freezing and thawing processes of the garbage, and inside the feeders, which are capable of traversing the left and right traversing the crushed garbage 39 on the punch plates 32 and 32 by the crusher 38, respectively. 31, 31, heat exchangers 35 a and 35 b that form a freezing or thawing or cold air heat source for the dispersed ground garbage, a refrigeration cycle 36 such as a heat pump that sends latent heat of vaporization or heat of condensation to the heat exchanger, Press rollers 34, 34 that can dehydrate the crushed raw garbage by pressing it onto the punch plate, can be moved up and down and left and right, scrapers 33, 33 for taking out the dehydrated crushed garbage to the outside from the punch plate, and a dehydration tank 37, 37, etc.
The evaporator and the condenser built in the refrigeration cycle 36 are alternately connected to the heat exchangers 35a and 35b. For example, when the heat treatment chamber 30a is used for freezing and the heat treatment chamber 30b is used for thawing, heat exchange is performed. The condenser 35a is connected to the evaporator, and the heat exchanger 35b is connected to the condenser.
When the heat treatment chambers 35a and 35b are used for freezing, the room temperature is kept at a low temperature of about 5 ° C. or lower to cause slow freezing at a low temperature.
[0034]
Since it is the said structure, if the crushed garbage 39 is spread | dispersed on the punch plate 32 in the heat processing chamber 30a through the feeder 31, for example, if cold heat is supplied from the freezing cycle 36 with the heat exchanger 35a, indoor temperature will be The ground garbage 39 which is kept at a low temperature of about 5 ° C. or less and is spread on the punch plate 32 as a result is placed in a slowly frozen state. In other words, the ground garbage is extracellular frozen, and large ice crystals are generated and grown in the cell gap. As a result, the cell tissue is directly subjected to mechanical repair that cannot be repaired, and the cell membrane is destroyed. Migrate out of the cell.
Then, if the heat of condensation is supplied to the heat exchanger 35a from the refrigeration cycle 36, the frozen garbage is thawed, but the retained water that has moved out of the cell has broken the cell membrane. Combined with the pressing force of a certain pressing roller 34, it is stored in the dewatering tank through the punching hole 32 a of the punch plate 32.
Thus, the phase change of water is caused with low energy, non-polluting dehydration is possible, and multipurpose resource recycling is possible.
[0035]
If sufficient dehydration cannot be expected only by freezing and thawing, the number of times of freezing and thawing is repeated a plurality of times, and if necessary, cold air drying is performed for the final finish.
[0036]
【The invention's effect】
As described above, according to the present invention, the solid matter of the concentrated sludge obtained from the waste water was freeze-dehydrated, so that the water contained in the cells of the solid matter was single-crystallized by freezing. By making it into ice and melting it, a dry cake with a very low water content can be obtained. The electric charge required for freeze dehydration is much smaller than the fuel cost required for the heat source of the conventional heating evaporation method, and the running cost can be reduced.
[0037]
Moreover, by dehydrating the dried cake to form a dehydrated cake and converting it into a solid fuel, not only can it be reused as an energy resource, but also the incineration treatment is not performed, so that the occurrence of pollution such as dioxins and odors can be suppressed.
[0038]
By the above-described wastewater drainage treatment of the present invention, it is possible to achieve pollution-free and efficient dehydration with low energy, and to achieve multipurpose resources.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a waste water treatment apparatus of the present invention.
FIG. 2 is a schematic diagram of a main part of FIG.
FIG. 3 is an explanatory view showing an example of the freeze dehydrating apparatus in FIG. 1;
FIG. 4 is a schematic diagram showing a schematic configuration of a garbage wastewater treatment apparatus in the present invention.
[Explanation of symbols]
2 Drainage 5 Sedimentation tank (initial sedimentation tank)
6 Settling tank (final settling tank)
DESCRIPTION OF SYMBOLS 8 Concentrated sludge tank 9 Freezing dehydration apparatus 11 Pelletization apparatus 12 Solid fuelization thing 14 Freezing room 15 Melting room 18 Turntable 19 Heat pump 20 Evaporator 21 Condenser 25 Waste water freezing separation apparatus 27 Ice machine 28 Thermal storage tank 30a, 30b Heat processing chamber 31 Feeder 32 Punch plate 33 Scraping machine 34 Press roller 35a, 35b Heat exchanger 36 Refrigeration cycle 37 Dehydration tank 38 Pulverizer 39 Pulverized garbage

Claims (7)

In the wastewater treatment method for separating sludge from wastewater containing solids and treating it as sludge cake,
The step of sending the waste water to a sedimentation tank to produce concentrated sludge, the step of freeze-drying the concentrated sludge to separate water and solids, and the dewatering of the dried cake produced in the freeze-dehydration step generating a dehydrated cake Te, the dehydrated cake was solidified Ri Do and a step of generating a solid fuel product, clarified supernatant drainage separated in the previous SL sedimentation tank is sent to ice machine drainage freezing separator A wastewater treatment method characterized in that water obtained by separating the ice into concentrated wastewater and melting the ice in a heat storage tank is used as intermediate water.   The freeze dehydration step of freeze-drying the concentrated sludge to separate water and solids is performed by repeatedly freezing and thawing to sufficiently dehydrate the concentrated sludge. Wastewater treatment method. Initial sedimentation tank and sedimentation tank consisting final sedimentation tank effluent, the initial settling tank and the concentrated sludge tank for storing concentrated sludge obtained in water and solid was freeze dried concentrated sludge from the concentrated sludge tank Doo and freezing dehydrator to separate to produce a dry cake to a centrifuge and dehydrated the dried cake to produce a dewatered cake, and pelletizing apparatus for solid fuel a dehydration cake, the A drainage freezing and separating device that neutralizes the supernatant drainage obtained in the final settling tank, and the drainage freezing and separating apparatus includes a refrigerator, an ice making machine, and a heat storage tank, and the supernatant drainage from the final settling tank. The ice is sent to the ice making machine and frozen to separate it into clear water (ice) and concentrated waste water, and the ice is sent to the heat storage tank, and the concentrated waste water is returned to the initial settling tank through a heat exchanger. configured things to be Waste water treatment apparatus according to claim.   The freeze dehydration apparatus includes a freezing chamber in which an evaporator connected to a heat pump is installed, a melting chamber in which a condenser connected to the heat pump is installed, and the concentrated sludge placed on the freezing chamber from the freezing chamber to the melting chamber. The wastewater treatment apparatus according to claim 3, comprising a turntable to be transferred. 5. The waste water treatment apparatus according to claim 4 , wherein the freeze dehydration apparatus is configured to allow repeated operation of freezing and thawing the concentrated sludge containing fine raw garbage by intermittent operation of the turntable.   A garbage grinder, a movable spreader that spreads the crushed garbage on a perforated backing plate, and a heat treatment of freezing, thawing, and cold air drying on the perforated backing plate and the crushed garbage that has been sprinkled on it. A freeze-drying chamber containing a pressure roller for dehydration, a refrigeration cycle that forms a heat source for freezing, thawing, and cold air, and a dehydrating tank provided below the backing plate. Garbage wastewater treatment equipment. 7. The raw material according to claim 6, wherein at least two freeze-drying chambers are provided, and the operation of freezing, thawing and dewatering is alternately performed a plurality of times by switching supply of heat from the refrigeration cycle. Waste water treatment equipment.

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