KR101887416B1 - De-watering Device of Livestock Excretions and De-watering Method thereof - Google Patents

Abstract

The present invention relates to a dewatering device for dewatering livestock manure including swine, comprising: a primary dehydrator including a decanter for dehydrating livestock manure; A dehydrating auxiliary agent which is mixed with the primary dehydrated cake dehydrated in the decanter to form sludge; And a filter press for dewatering the formed sludge.
Therefore, it is possible to improve the coagulation ability of the sludge produced by the first dehydrated cake and to improve the dewatering ability by using a dehydrating auxiliary agent having less corrosiveness, to reduce the water content of the cake, and to provide the optimum dehydration aid amount and mixing time can do.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehydrating apparatus for a livestock manure,

The present invention relates to a dewatering apparatus for a livestock manure and a dewatering method thereof, and more particularly to a dewatering apparatus and a dewatering method for a livestock manure wherein the structure is improved so as to form a livestock manure dewatering cake which can be remarkably reduced in water content will be.

The number of domestic livestock breeding is estimated to be about 230 million as of 2013, with about 92% of chickens, ducks, about 4% of pigs, and about 4% of other cattle such as cows and horses. Due to the increase in consumption, the number of livestock rearing has been increasing every year for the past 5 years (2007 ~ 2013).

The amount of livestock manure produced by pigs accounted for 52% (89.915 ㎥ / day) of the total livestock manure output among the domestic livestock manure output (173,052 ㎥ / day) as of 2013, 20,840 ㎥ / day, small 43,369 ㎥ / day, and chicken and duck 17,234 ㎥ / day).

Various legislations have been pursued for the regulation, treatment and utilization of livestock manure. In order to improve the economic efficiency and to achieve the goal of environment-friendly livestock farming and prevention of water pollution through proper manure management and recycling of livestock manure, priority is given to the establishment of reclamation / livestock recycling facilities for conversion from recycling treatment to recycling facilities considering regional characteristics The Ministry of Environment and the Ministry of Food, Agriculture, Forestry and Fisheries have promulgated the Law on the Management and Use of Livestock Manure (Livestock Manure Act) (2006.09) and implemented it (2007.10).

This type of livestock manure treatment and usage differs depending on the case of mixing with the case of separating 'min' and 'urine', and various methods such as composting, liquefaction, purification treatment, .

At present, about 90% of domestic livestock manure is being recycled as fertilizer and livestock, but since it is recognized as a main pollutant source such as soil and river, environmental regulations such as revision of livestock manure method are constantly strengthened. · Liquid fertilizer is the main cause of the occurrence of green tide. In addition, there is a disadvantage that the supply is overcome due to time and space constraints, and economical efficiency is low.

On the other hand, the biogas plant for energizing livestock manure has many difficulties in commercialization of private initiative due to low anaerobic digestion efficiency, stable operation and insufficient policy base in Korea. In the case of solid fueling, the drying energy required to lower the high water content of the manure has a thermodynamic limitation, which is more necessary than the energy produced, so it is necessary to solve the problem of energy production.

In particular, pig manure in livestock manure is a slurry form and has technical limitations in terms of cost, odor, quality, environmental pollution, etc. frequently encountered in the recycling treatment in individual farms where processing technology and operation are insufficient.

Currently, livestock manure including pig manure is treated with decanter dehydrator, and the water content of the final dehydrated cake is very high, around 80%.

Such a high water content dewatering cake is subjected to a subsequent drying process using a high temperature heater for the purpose of solidification of the fuel, and in the case of complete drying in which the water content is reduced to 30 wt% or less, the dry sludge is recycled as a raw material for cement or an industrial fuel In the case of partial drying where the water content is reduced to 60 wt%, the sludge incineration is being carried out at the previous stage in order to minimize fuel consumption.

Therefore, the development of a technology capable of producing a water content of the final dewatering cake of less than 60% by improving the dewaterability of the livestock manure which is dehydrated is very important in terms of energy saving for solid fuel conversion and reduction of waste disposal cost through sludge reduction It is a useful technique.

Prior art related to the present invention is a livestock manure disposal facility of the registered patent publication No. 723338 (published on May 30, 2007), a livestock manure treatment facility of Laid-open Patent Publication No. 2014-0013491 (published on April 2, 2015) Liquid separator for manure ", and the like.

It is an object of the present invention to provide a dewatering device for a livestock manure which can improve the coagulation ability of the sludge produced from the first dewatered cake and improve the dewatering ability by using a dehydrating auxiliary agent having low corrosiveness and to reduce the water content of the cake, Thereby providing a dehydration method.

Another object of the present invention is to provide a dehydrating apparatus for a livestock manure capable of providing an optimal amount of dehydrating auxiliaries to be used and a mixing time, and a dehydrating method thereof.

Still another object of the present invention is to provide a dewatering apparatus and a dewatering method of a livestock manure which can easily and easily obtain a dewatering cake having a water content of 60 wt% or less.

Still another object of the present invention is to provide a dehydrating apparatus for a livestock manure and a dehydrating method thereof, which can improve the recycling rate of the dehydrated cake and reduce the cost in the case of drying and the like.

It is still another object of the present invention to provide a dehydrating apparatus for a livestock manure and a dehydration method therefor which can easily and conveniently improve the economic effect of the dehydrated livestock manure sludge by dehydrating the cake dehydrated primarily through the decanter .

An object of the present invention is to provide a dewatering device for dewatering livestock manure containing pig powder, comprising: a primary dehydrator including a decanter for dehydrating livestock manure; A dehydrating auxiliary agent which is mixed with the primary dehydrated cake dehydrated in the decanter to form sludge; And a filter press for dewatering the sludge formed by the primary dewatering cake and the dewatering aid, wherein the water content of the dewatered cake dewatered in the primary dewatering device is in the range of 83 wt% to 77 wt% and is dehydrated by the filter press Wherein the water content of the formed cake is in the range of 65 wt% to 55 wt%, and the dehydrating assistant comprises an OH group and a sulfate ion (SO ₄ ^2- ), wherein the mixing amount of iron ions in the dehydrating assistant is 3 to 5 wt% And a dewatering device.

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It is preferable that the dehydration aid contains 0.07 wt% or less of ferrous iron (Fe (II)) and 24 to 29 wt% of sulfate ion (SO ₄ ^2- ).

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The filter press includes a plurality of filter plates. The filter plate includes a compression filtration plate. The sludge is conveyed to a set target pressure by the filtration plate, and a squeezing fluid containing air or water is supplied to the squeezing filtration plate, It is preferable to squeeze and dewater the cake collected inside the filter plate.

In addition, it is preferable that the thickness of the cake formed by the width of the filter chamber, which is the space between the filter plate and the filter plate, is 30 to 25 mm.

The mixing time of the primary dewatering cake and the dehydrating auxiliary is preferably 3 to 5 minutes.

It is preferable that the primary dehydrating cake and the dehydrating auxiliary agent are mixed by a line mixer.

It is another object of the present invention to provide a method of dewatering livestock manure including pigs, comprising the steps of (1) dewatering livestock manure into a primary dehydrator including a tester; (2) a step of mixing the primary dehydrated cake dehydrated in the primary dehydrator and the dehydrating auxiliary to form a sludge; And dewatering the sludge formed in the step (2) to a filter press, wherein a water content of the dewatered cake dehydrated in the first dehydrator is in a range of 83 wt% to 77 wt%, and the dewatered cake Wherein the dehydrating assistant comprises an OH group and sulfuric acid ions (SO ₄ ^2- ), wherein the mixing amount of the iron ions in the dehydrating assistant is 3 to 5 wt% based on the weight of the solid matter, wherein the water content is in the range of 65 wt% to 55 wt% The method of the present invention is also achieved by a manure dewatering method.

According to the present invention, it is possible to improve the coagulation ability of the sludge produced from the primary dewatered cake and to utilize the dewatering aid having low corrosivity to improve the dewatering ability and reduce the water content of the cake, The present invention can provide a dehydrating apparatus for a livestock manure and a method of dehydrating it.

Also provided is a dewatering apparatus and dewatering method for a livestock manure which can easily and easily obtain a dewatering cake having a water content of 60 wt% or less and improve the recycling rate of the dewatering cake or reduce the cost in the case of drying can do.

Also, it is possible to provide a dewatering apparatus and a dewatering method of a livestock manure which can primarily and easily re-dewater the cake dehydrated by a dehydrator including a decanter to improve the economical effect of the dehydrating livestock manure sludge.

FIG. 1 is a conceptual view for explaining an operation process of a dewatering device according to an embodiment of the present invention;
Fig. 2 is a schematic view showing an example of a test facility for dehydration test of manure,
FIG. 3 is a graph showing changes in the amount of the dehydrating auxiliary added and the rate of the filtrate discharge over time,
4 is a graph showing the filtrate discharge rate according to the mixing time of the primary dewatering cake and the dehydrating auxiliary agent,
5 is a flowchart illustrating a dehydration method according to an embodiment of the present invention.

A dewatering apparatus and dewatering apparatus (hereinafter, referred to as 'dewatering apparatus') according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3 below.

FIG. 1 is a conceptual view for explaining the operation of a dewatering apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view showing an example of a test facility for dewatering test of manure. FIG. 4 is a graph showing the filtrate discharge rate according to the mixing time of the primary dewatering cake and the dewatering auxiliary agent, FIG. 5 is a graph showing the filtrate discharge speed according to the embodiment of the present invention, Fig.

1, according to an embodiment of the present invention, as shown in FIG. 1, manure of various livestock including pigs is pretreated by various known biochemical methods, and the concentrated enrichment tank 30 The concentrated slurry is transferred to the first dehydrator 110 including the decanter by the concentrated slurry transfer pump 113 through the concentrated slurry transfer line 115 to separate the filtrate and the cake, that is, to separate the cake as the solid component and the liquid component The filtrate is separated from each other (see step S210 of FIG. 5). The primary cake generated in this process is transferred to the mixing section 150 including the line mixer along the primary dewatering cake transfer line 117.

At this time, the water content of the first cake dehydrated in the first dehydrator 110 is about 80 wt%.

The primary dewatering cake transferred to the mixing unit 150 is mixed with the dehydrating auxiliary transferred from the dewatering auxiliary unit 130 and the mixing unit 150 for a certain period of time (refer to step S230 of FIG. 5). The dehydrating auxiliary agent preferably contains 0.07 wt% or less of ferrous (Fe (II)) and 24 to 29 wt% of sulfate (SO ₄ ^2- ). Such a dehydrating auxiliary agent has a three-dimensional coordination structure in which a part of SO ₄ ^2- in ferric sulfate is transferred to OH ^- , and the OH group is polymerized as a crosslinking to form a polynuclear complex (multinuclear complex) The sludge mixed with the sludge can be improved in cohesion ability, and since it has a basicity, consumption of alkalinity is small and corrosiveness is low.

That is, since the applicant has studied a dehydration method for an egg-dehydrated manure wastewater, which is difficult to dehydrate for several decades and is difficult to lower the water content, a means derived from a number of mistakes is a dehydrating aids. Such dehydrating auxiliaries are believed to partially degrade the water molecules associated with the solid particles forming the cake to improve the dehydration properties, and Applicants will further study this structure.

The dewatering auxiliary part 130 is connected to the auxiliary agent feeding line 135 for feeding the auxiliary agent storage tank 131 for storing the dehydrating auxiliary agent and the auxiliary agent storage tank 131 to the mixing part 150 and the auxiliary agent feeding line 135 And an auxiliary transferring pump 133 for pressurizing the dehydrating auxiliary agent to the mixing portion 150. [

For example, the dehydration aid may detect the transfer amount of the first dehydration cake by an unshown sensor and calculate the total solid content in the first dehydration cake in the controller 190 considering the water content of the first dehydration cake.

Based on the total solid content in the primary dewatering cake, for example, the auxiliary section feed pump 133, which is supplied in a fixed amount, can be operated by the control section 190. The controller 190 can control the mixing of the primary dehydrating cake and the dehydrating auxiliary agent in a stable manner in the mixing unit 150 by supplying the dehydrating auxiliary agent in a fixed ratio to the total solid content of the primary dehydrating cake .

Next, the sludge mixed in the mixing unit 150 is transferred to the filter press 170 (refer to step S250 of FIG. 5).

That is, the mixed sludge along the mixed sludge conveying line 175 between the filter presses 170 in the mixing unit 150 is pressurized and conveyed by the mixed sludge conveying pump 173. Here, the mixed sludge conveying pump 173 may use various known pumps, but mono pumps, diaphragm pumps, etc. may be used in the present invention.

A plurality of filter plates 171, which are key constituent elements of the filter press 170, are preferably provided, and a part or all of the filter plates 171 is preferably a compression filtration plate 171b. In this embodiment, an example is a filter plate 171 in which a general filter plate 171a and a compression filter plate 171b are alternately arranged.

Here, the filter press 170 includes a pressurized fluid supply line 179 to which a pressurized fluid including water or air (mainly water) is supplied to the pressurized filtration plate 171b and a pressurized fluid supply line 179 supplied from the pressurized fluid supply line 179, A pressurized fluid head 179a for distributing the pressurized fluid to the press filtration plate 171b and a pressurized fluid hose 179b for supplying a pressurized fluid to each pressurized filtration plate 171b at the pressurized fluid head 179a. The space between the filter plates 171 is the width of the cavity (refer to 't' in FIG. 1), the width becomes the cake thickness, and the press dewatering cake 177 is formed. However, the cake formed in the chamber can be further dewatered and thinned by the compression bonding plate 171b.

The sludge mixed by the filter press 170 having such a constitution is mixed with the mixed sludge by the mixed sludge conveying pump 173 through the mixed sludge conveying line 175 in the mixing part 150 and the filtration plate 171 of the filter press 170 And pressurized to the inside of the room (refer to step S250 of FIG. 5).

The sludge under pressure is collected in the filter chamber by the filter cloth (not shown) surrounding the surface of the filter plate 171 to be caked, and the filtrate or filtrate that has passed through the filter cloth is discharged again to the thickening tank 30 or the like.

In this process, the control unit 190 can set the pressurizing pressure of the mixed sludge conveying pump 173 that pressurizes the mixed sludge, and can select the set pressure as the target pressure. That is, it is possible to control the control unit 190 to stop the conveyance of the mixed sludge after a predetermined time has elapsed after reaching the target pressure of the mixed sludge conveying pump 173.

After the mixed sludge conveying pump 173 completes the dewatering of the mixed sludge by the pressure, the pressurized fluid containing water is supplied to the pressurizing filter plate 171b to press the cake formed between the filter plates 171 again, The moisture content of the cake can be further reduced to further reduce the water content of the cake (refer to step S250 of FIG. 5).

Hereinafter, the test, experiment, etc. of the dewatering apparatus 100 according to the present invention will be described in detail as follows. An example of the sludge is dung from among livestock manure.

2 is a miniature test facility 300 in which the dewatering device according to the present invention is reduced.

In the test facility 300 used in the experiment, the main body 321 in which the sludge mixed with the primary dehydration cake mixed with the dehydrating auxiliary agent is accommodated has an inner diameter of 14 cm and a height of 25 cm, and the filtration area of the filtration plate 327 through which the lower filtrate passes the 154 cm ^2, which contains a main body 321, a dewatering aid and a blend of the primary dehydration, and a certain amount injected into the cake, the main body 321 of the inside by the piston 315 installed in the upper main body 321, transfer plate (323, described above in ) Is a pressurized small test facility that squeezes sludge at a constant pressure.

The sludge of the main body 321 is accommodated in the upper and lower portions of the filter body 325 and the filter plate 327. The pressure applied to the cake layer causes moisture to flow through the cake layer and the filter cloth 325 and the pores of the filter plate 327 The filtrate discharged into the lower part of the main body 321 and accommodated in the container along the filtrate line 331 and accommodated therein can be measured by the scale 333. That is, the dehydrated filtrate discharged to the lower portion of the main body 321 is collected in a container installed in the lower portion of the main body 321, and the amount of the dewatered fluid over time can be measured with the scale 333.

The piston 315 which pressurizes the main body 321 is provided with a valve 317, a pressure regulator 310, a pressure gauge 313 and the like in a compressed air pipeline line which is pressurized by compressed air and is pressurized, The pressure of the compressed air can be measured.

Here, for reference, it is a reddish brown liquid of a dehydrating aid and has a specific gravity (20 占 폚) of about 1.45 to 1.49 and a viscosity (20 占 폚) of 10 to 30 cps. In addition, the pH (1w / v%) is 2 or more, the total Fe is 11% or more, the chlorine ion (Cl ^- ) is 0.05wt% or less and the freezing point is 12 ± 1 ° C.

1% by weight of the iron (Fe) ion contained in the dehydrating auxiliary agent as compared with the solids weight of the dough dewatering cake (moisture content 75 to 80%) dehydrated with the first dehydrator of the decanter by the test equipment 300, , 3%, 5%, and 7%, respectively. The results are shown in FIG. 3 as a graph of the discharge rate of the dehydrated filtrate.

In this process, the pressure applied to the cake layer was maintained at 15 bar during the entire period from the beginning to the end of dehydration. According to FIG. 3, as the amount of the dehydrating additive increased, the discharge rate of the dehydrated filtrate increased. As shown in [Table 1].

Dehydrating agent 0% One% 3% 5% 7% Final water content 69.0% 65.5% 58.3% 58.0% 55.4%

As shown in the above results, in order to produce a dehydrated cake having a moisture content of 60% or less, it is understood that the dehydrating auxiliaries used in the present invention should be added by 3% or more based on the weight of iron (Fe) ions to the weight of the livestock manure solids.

However, it may be appropriate to control the addition amount in consideration of the characteristics and economy of livestock manure, and it is more preferable that the dehydrating auxiliary agent is in the range of 3% to 5% based on the weight of iron (Fe) ion based on the weight of the livestock manure solids.

In order to investigate the dewaterability according to the degree of mixing of the dehydrating cake and the dehydrating auxiliaries, a dehydrating aid was added to the dehydrating cake (moisture content 75 to 80%) based on the weight of the iron (Fe) %, And the mixing time was set to 0 min, 3 min, 10 min, 20 min, 30 min, 40 min and 50 min, respectively.

In this case, the pressure applied to the cake layer was maintained at 15 bar during the entire period from the beginning to the end of dehydration. As shown in FIG. 4, when the mixing time was 3 min, the best filtrate flow rate was exhibited. It was found that it was getting worse.

Therefore, it can be seen that the mixing of the primary dehydrated cake and the dehydrating auxiliary agent of the flour livestock manure according to the present test is more advantageous than the dehydrating method in the case of the line mixer without the need of a special mixing device. It is understood that this feature will be a very useful advantage in terms of the actual dewatering device configuration and productivity.

On the other hand, in the mixed sludge dewatering process, the cake thickness affects the water content and the dewatering rate. When the cake thickness is small, the water content of the final dewatering cake decreases but the number of filter plates of the dewatering device increases. .

Here, in this experiment, it was tried to grasp the optimal cake thickness to make the water content of the dewatered cake produced in the filter press 170 less than 60% through the final dewatering of the livestock manure using the filter press 170.

The pilot dehydrator used in this experiment was a pilot filter dewatering device with a filter plate size of 470 mm in width and 4 mm in length. The dewatering efficiency of each cake thickness was analyzed by adjusting the cake thickness to 25 mm, 30 mm, 35 mm and 50 mm .

The means for transferring the mixed sludge to the pilot filter press used a mono pump. When the pressure of the mono pump reached 10 bar, the conveying of the mixed sludge was stopped. After that, The cake was finally squeezed and dewatered with water,

Table 2 below shows the operating conditions and results for the dewatering experiment according to the cake thickness.

Filter press Cake thickness mm 25 30 35 50 Filtration area m ² / Ch 0.31. Filtration volume L / Ch. 3.5 4.1 4.7 6.6 Livestock manure Moisture content % 76 Dehydrating agent Addition amount Fe 5% by weight of livestock manure solids weight Operating condition Dehydration time min 60 Dehydration pressure bar 15 result Cake thickness mm 14 23 27 37 Cake moisture rate % 55.9 61.8 64.9 67.1 Dehydration speed DSkg / m ² .cycle 3.2 3.6 4.1 5.5

As shown in Table 2, the larger the cake thickness, the greater the throughput and the water content of the final dewatering cake increased. The smaller the cake thickness, the smaller the throughput but the lower the water content of the final dewatering cake .

 Therefore, it is preferable that the cake thickness of the filter press dewatering device is 30 mm or less when producing the dewatered cake having a water content of less than 60% by rehydration of the livestock manure with the filter press.

However, considering the throughput and economic efficiency of livestock manure as a whole, it is more preferable to appropriately control the thickness of the cake depending on the amount of the dehydrating auxiliaries to be added and the operation conditions.

Here, when 1,000 kg of cake having a water content of 80 wt% (800 kg of water, 200 kg of solid content) has a water content of 60 wt%, the cake amount is 500 kg (300 kg of water, 200 kg of solid content)

In addition, when the water content of the cake is reduced, the cost for drying and the like is drastically reduced, and the economic effect is greatly increased. In other words. Since the water content of the cakes produced in the sludge of the dehydration runoff sludge can be dehydrated to a low water content of 60 wt% or less, it is believed that economical efficiency and eco - friendliness will be increased due to reclamation, incineration, recycling and energy resources such as solid fuel. In addition, there is a possibility that the present invention may be applied to a field where it is difficult to induce a low water content by machine dehydration including not only manure wastewater but also other kinds of filter presses.

Therefore, according to the present invention, it is possible to improve the coagulation ability of the sludge produced from the first dewatered cake and to improve the dewatering ability using the dehydrating auxiliary agent having low corrosiveness and to reduce the water content of the cake, And a mixing time of the animal manure can be provided.

Also provided is a dewatering apparatus and dewatering method for a livestock manure which can easily and easily obtain a dewatering cake having a water content of 60 wt% or less and improve the recycling rate of the dewatering cake or reduce the cost in the case of drying can do.

Also, it is possible to provide a dewatering apparatus and a dewatering method of a livestock manure which can primarily and easily re-dewater the cake dehydrated by a dehydrator including a decanter to improve the economical effect of the dehydrating livestock manure sludge.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art to which the present invention pertains, will be. The scope of the invention will be determined by the appended claims and their equivalents.

100: Dewatering device 30: Enrichment tank
110: primary dehydrator 113: concentrated slurry transfer pump
115: Concentrated slurry transfer line 117: Primary dewatering cake transfer line
130: dehydrating auxiliary part 131: auxiliary tank
133: Adjuvant delivery pump 135: Adjuvant delivery line
150:
170: Filter press 171: Filter plate
171a: General filter plate 171b:
173: Mixed sludge transfer pump 175: Mixed sludge transfer line
177: Press dehydrated cake 179: Pressurized fluid supply line
179a: Compressed fluid head 179b: Compressed fluid hose
190:

Claims (12)

1. A dewatering device for dewatering livestock manure including swine,
A primary dehydrator including a decanter for dehydrating livestock manure;
A dehydrating auxiliary agent which is mixed with the primary dehydrated cake dehydrated in the decanter to form sludge;
And a filter press for dewatering the sludge, which is a mixture formed by mixing the primary dehydrating cake and the dehydrating auxiliary agent,
The water content of the dehydrated cake dehydrated in the primary dehydrator is in the range of 83 wt% to 77 wt%, and the water content of the cake dewatered by the filter press is in the range of 65 wt% to 55 wt%
Wherein the dehydrating assistant comprises an OH group and a sulfate ion (SO ₄ ^2- ), wherein the mixing amount of iron ions in the dehydrating auxiliary agent is 3 to 5 wt% based on the weight of the solids. delete The method according to claim 1,
Wherein the dehydration assistant contains 0.07 wt% or less of ferrous iron (Fe (II)) and 24 to 29 wt% of sulfate ion (SO ₄ ^2- ). delete The method according to claim 1,
Wherein the filter press comprises a plurality of filter plates, wherein the filter plate comprises a compression filtration plate
Wherein the sludge is conveyed to a set target pressure by the filter plate, and a squeezing fluid containing air or water is supplied to the squeezing filter plate to squeeze and dewater the cake caught in the filter plate. 6. The method of claim 5,
Wherein a thickness of the cake formed by the width of the filter chamber, which is a space between the filter plate and the filter plate, is 30 to 25 mm. The method according to claim 1,
Wherein the mixing time of the primary dewatering cake and the dewatering auxiliary is 3 to 5 minutes. 8. The method of claim 7,
Wherein the first dehydrating cake and the dehydrating auxiliary agent are mixed by a line mixer. A method for dewatering a livestock manure including pigs,
(1) dewatering livestock manure with a primary dehydrator comprising a tester;
(2) a step of mixing the primary dehydrated cake dehydrated in the primary dehydrator and the dehydrating auxiliary to form a sludge;
And dewatering the sludge, which is a mixture formed in the step (2), with a filter press,
The water content of the dehydrated cake dehydrated in the primary dehydrator is in the range of 83 wt% to 77 wt%, and the water content of the cake formed by dewatering by the filter press is in the range of 65 wt% to 55 wt% SO ₄ ^2- ), wherein the mixing amount of iron ions in the dehydrating auxiliary agent is 3 to 5 wt% based on the weight of the solids. 10. The method of claim 9,
Wherein the dehydrating auxiliary agent comprises 0.07 wt% or less of ferrous iron (Fe (II)) and 24 to 29 wt% of sulfate ions (SO ₄ ^2- ). 11. The method according to claim 9 or 10,
Wherein the filter press comprises a plurality of filter plates, wherein the filter plate comprises a compression filtration plate
Further comprising feeding the sludge to a target pressure set by the filter plate and then supplying a squeezing fluid containing air or water to the squeezing filter plate to squeeze and dewater the cake collected in the filter plate, . 11. The method of claim 10,
Wherein the mixing time of the decanter dehydrating cake and the dehydrating auxiliary agent is 3 to 5 minutes.

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