Wastewater Treatment System

Abstract

To provide a wastewater treatment system that requires simple equipment, has a short treatment time, low equipment costs and operation costs, and can sufficiently reduce coloration of treated wastewater. [Solution] A wastewater treatment system that separates and purifies wastewater from washing discharged from livestock barns, comprising a treated water tank 120 into which the supernatant components of the wastewater are introduced by a supernatant transfer unit 121, a first filtration tank 130 into which the supernatant components of the treated water tank 120 are introduced by a first treated water transfer unit 131, a second filtration tank 140 into which liquid components that have passed through the first filtration tank 130 are introduced by a second treated water transfer unit 141, and a decolorization treatment tank 160 into which liquid components that have passed through the second filtration tank 140 are introduced by a decolorization treatment water transfer unit 161.

Description

[Technical Field]

[0001] The present invention relates to a wastewater treatment system for separating and purifying wastewater from washings discharged from livestock barns. [Background technology]

[0002] The wastewater discharged from livestock sheds for washing has a strong odor, is turbid, discolored, and has a high BOD value. When treating these, it is possible to separate the solid wastewater from the liquid wastewater, add dilution water to the wastewater, and then discharge it or allow it to permeate underground, but it has been difficult to produce purified water that can be discharged without causing environmental pollution. Furthermore, as a method for lowering the BOD value so as to reduce the environmental load, a method of treating wastewater in an aeration tank containing microorganisms that treat organic matter and aerate the wastewater is known.

[0003] For example, in a wastewater treatment system known from Patent Document 1 and the like, the system is equipped with a raw water tank for temporarily storing parlor wastewater, a screen for removing coarse solids contained in the parlor wastewater, a storage tank for storing the parlor wastewater from which the coarse solids have been removed, a first settling tank for separating and precipitating the parlor wastewater, an aeration tank containing microorganisms for treating organic matter contained in the parlor wastewater and aerating the parlor wastewater, and a second settling tank for separating and precipitating the treated parlor wastewater, and the liquid components separated from the solids are purified by the microorganisms in the aeration tank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-87968 [Patent Document 2] Japanese Patent Application Publication No. 2023-161382 Summary of the Invention [Problem to be solved by the invention]

[0005] In known wastewater treatment systems, it is possible to reduce the BOD value by sufficiently decomposing organic matter in an aeration tank. However, treating large amounts of wastewater requires a large installation area, a long treatment time, and high equipment costs, such as pump equipment for aeration, as well as high operating costs.

[0006] With the aim of solving these problems and providing a wastewater treatment system that requires simple equipment, has short treatment times, low equipment and operating costs, and can sufficiently reduce the BOD value of treated wastewater, the inventors invented the wastewater treatment system shown in Patent Document 2. In one embodiment of the wastewater treatment system described in Patent Document 2, treated water can be obtained in which the BOD (biochemical oxygen demand), COD (chemical oxygen demand), SS (suspended solids), and phosphorus levels have all been reduced to levels below the general wastewater standards set by the Ministry of the Environment in accordance with the Water Pollution Control Act, and the treated water can be reused as cleaning water for the parlor in the cowshed, or it can be discharged as is.However, because the first and second filtration tanks use ``Marton Chips'' (registered trademark), which are porous wood chips, as filtering material, there is an issue that a yellowish-brown color remains in the treated water. If treated water with such residual coloring is reused as washing water for the parlor in the cowshed, there is a risk that the color will transfer to the parlor in the cowshed, accelerating its contamination. Furthermore, if the water was discharged as is, local residents and others might mistakenly believe that untreated water was being discharged as is, which could cause problems with the discharge.

[0007] The present invention has been made in light of the above circumstances, and aims to provide a wastewater treatment system that requires simple equipment, has a short treatment time, low equipment costs and operating costs, and can sufficiently reduce the discoloration of wastewater after treatment. [Means for solving the problem]

[0008] The present invention solves the above problem by providing a wastewater treatment system that separates and purifies wastewater from washings discharged from livestock barns, comprising a treated water tank into which the supernatant components of the wastewater are introduced by a supernatant transfer unit, a first filtration tank into which the supernatant components of the treated water tank are introduced by a first treated water transfer unit, a second filtration tank into which liquid components that have passed through the first filtration tank are introduced by a second treated water transfer unit, and a decolorization treatment tank into which liquid components that have passed through the second filtration tank are introduced by a decolorization treatment water transfer unit. [Effects of the Invention]

[0009] According to the wastewater treatment system of the invention of claim 1, the liquid components of the wastewater can be purified as it passes continuously through the first filtration tank and the second filtration tank, thereby reducing the equipment costs and operating costs of pump equipment for aeration, etc. In addition, by having a treated water tank into which the supernatant components of the wastewater are introduced by a supernatant transfer unit, even if solid-liquid separation processing is performed intermittently upstream of the treated water tank, the supernatant components of the wastewater can be stored in the treated water tank and continuously sent to the first filtration tank and second filtration tank as a buffer. This allows the first filtration tank and the second filtration tank to be kept in continuous operation at all times, allowing for effective use of the facilities. Furthermore, by providing a decolorization treatment tank into which the liquid component that has passed through the second filtration tank is introduced by the decolorized water transfer unit, it is possible to reduce the coloring of the wastewater after treatment. In addition, the liquid components that have passed through the second filtration tank are introduced into the decolorization treatment tank by the decolorization treatment water transfer unit, so that treated water with sufficiently reduced SS (suspended matter) and other substances can be efficiently decolorized, and the operating costs of the decolorization treatment tank can also be reduced.

[0010] According to the configuration described in claim 2, by having multiple raw water tanks and a sludge tank into which sedimentary components from the raw water tanks are introduced by the first sludge transfer unit, it is possible to introduce wastewater into one raw water tank and allow it to settle for a predetermined period of time while introducing wastewater into another raw water tank, thereby improving treatment efficiency by allowing wastewater to be continuously introduced while sufficient solid-liquid separation is carried out by sedimentation.

[0011] According to the configuration described in claim 3, the decolorization treatment tank has one or more decolorization treatment layers, and at least one of the decolorization treatment layers contains activated carbon as a decolorization treatment material, thereby further reducing the discoloration of the wastewater after treatment. According to the configuration of claim 4, the bleaching treatment layer is provided on a support member having through holes, so that the bleaching treatment material can be adjusted or replaced for each bleaching treatment layer. According to the configuration of claim 5, the activated carbon contains rice husk activated carbon, so that the decolorization treatment can be carried out using inexpensive and easily available materials. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a wastewater treatment system according to an embodiment of the present invention. [Figure 2] 1 is an explanatory plan view of a wastewater treatment system according to an embodiment of the present invention; [Figure 3] 1 is an external view of treated water in a wastewater treatment system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] As shown in Figures 1 and 2, the wastewater treatment system 100 of one embodiment of the present invention has a plurality of raw water tanks 110 into which washing wastewater discharged from livestock barns is introduced by a wastewater introduction unit 111, where a treating agent is added and stirred by a stirring unit 112, and then sedimentation separation is carried out; a treated water tank 120 into which the supernatant components of the raw water tank 110 are introduced by a supernatant transfer unit 121; a first filtration tank 130 into which the supernatant components of the treated water tank 120 are introduced by a first treated water transfer unit 131; a second filtration tank 140 into which liquid components that have passed through the first filtration tank 130 are introduced by a second treated water transfer unit 141; and a decolorization treatment tank 160 into which liquid components that have passed through the second filtration tank 140 are introduced by a decolorization treatment water transfer unit 161. The system also includes a sludge tank 150 into which sediment components from the plurality of raw water tanks 110 are introduced by a sludge transfer unit 151 .

[0014] The sludge tank 150 is located below the bottom of the raw water tank 110 and the treated water tank 120. In this embodiment, the raw water tank 110, the treated water tank 120, the first filtration tank 130, and the second filtration tank 140 are separated by partitions rising from the floor, and the sludge tank 150 is located below the floor as a culvert. A sludge manhole 115 is provided at the bottom of the raw water tank 110 to accumulate sludge containing solids that are sedimentary components, and a sludge transfer unit 151 is configured to transfer the sludge accumulated in the sludge manhole 115 to the sludge tank 150.

[0015] The first filtration tank 130 and the second filtration tank 140 are filled with a filtering material made of porous wood chips, and the liquid components introduced from the first treated water transfer unit and the second treated water transfer unit are configured to be showered onto the upper surface of the filtering material and penetrate evenly. In addition, bottom piping 135, 145 consisting of a pipe member with multiple inlet holes on the side is arranged at the bottom of the first filtration tank 130 and the second filtration tank 140, and is configured to efficiently recover liquid components that have passed through the filtration material. In this embodiment, two raw water tanks 110 are provided, but three or more tanks may be provided. Furthermore, the first filtration tank 130 is divided into two tanks, and is configured with a total capacity twice that of the second filtration tank 140, but the capacity ratio may be set appropriately depending on the passing speed of each liquid component. Furthermore, it is desirable to provide blower piping at the mid-height portion of the first filtration tank 130 and the second filtration tank 140 to prevent clogging due to small amounts of solid matter mixed in and to maintain the activity of microorganisms.

[0016] As shown in FIG. 1, the bleaching treatment tank 160 has a bleaching treatment layer 162 consisting of three layers: a first bleaching treatment layer 162a provided on a first support member 163a, a second bleaching treatment layer 162b provided on a second support member 163b, and a third bleaching treatment layer 162c provided on a third support member 163c. The decolorizing treatment layer 162 is filled with a decolorizing treatment material made of porous activated carbon, and the liquid components introduced from the decolorizing treatment water transfer unit 161 are configured to be showered onto the upper surface of the decolorizing treatment material of the first decolorizing treatment layer 162a so as to penetrate evenly. Here, since each decolorizing treatment layer 162 is provided on a support member 163, the amount of decolorizing treatment material filled can be adjusted according to the flow rate of the liquid component introduced into the decolorizing treatment tank 160, and the decolorizing treatment material can be replaced individually for each decolorizing treatment layer 162, thereby reducing equipment costs and operating costs. In addition, a bottom piping 165 consisting of a pipe member with multiple inlet holes on the side is arranged at the bottom of the decolorization treatment tank 160, and is configured to efficiently recover liquid components that have passed through the decolorization treatment layer 162. In this embodiment, one decolorization treatment tank 160 is provided, but two or more tanks may be provided.

[0017] A specific flow of treatment when treating wastewater discharged from a parlor in a cowshed (a place where milk is taken out) using the wastewater treatment system 100 configured as above will be described. The capacity of each tank is as follows: Raw water tank ···Approx. 35m 3 *2 1st filtration tank ···Approx. 40m 3 *2 2nd filtration tank ·Approx. 40m 3 Treatment tank: Approx. 90m 3 Furthermore, "Marton Chip" (registered trademark) was used as the filtering material for the first filtration tank 130 and the second filtration tank 140.

[0018] First, wastewater from the parlor in the cowshed is pumped into one raw water tank 110 by a pump provided in the wastewater introduction unit 111 until the volume reaches 30 tons. When 30 tons of wastewater is introduced into one raw water tank 110, the motorized ball valve connected to one raw water tank 110 is closed, and the motorized ball valve connected to the other raw water tank 110 is opened. Next, the processing agent is added to one of the raw water tanks 110 while stirring with the stirring unit 112 . In this embodiment, polyferric sulfate solution, caustic soda solution, and polymer coagulation accelerator (Z Floc C-101) were used as the treatment agents. Using a metering pump (not shown), 45 L of polyferric sulfate is injected over 2 minutes, followed by 20 L of caustic soda solution over 2 minutes, and finally 450 L of polymer coagulation accelerator is injected over 3 minutes. When the chemical is injected into the raw water tank 110, the electric ball valve connected to one of the raw water tanks 110 in the piping of the metering pump is closed, and the electric ball valve connected to the other raw water tank 110 is opened.

[0019] After stirring for another 2 minutes or so, the operation of the stirring unit 112 is stopped temporarily, and after stirring in the reverse direction for 1 minute, the operation of the stirring unit 112 is stopped and the mixture is left to stand for 30 minutes to 1 hour. Next, the pump of the supernatant transfer unit 121 is operated to transfer the supernatant components to the treated water tank 120 , and the pump of the sludge transfer unit 151 is operated to transfer the precipitate components to the sludge tank 150 . At this time, the pump of the sludge transfer unit 151 repeats intermittent operation of being on for 10 seconds and off for 20 seconds until the pump of the supernatant transfer unit 121 stops operating. After that, the stirring motor is operated for about 20 seconds to transfer the sludge remaining at the bottom of the raw water tank 110 to the sludge tank 150 by continuously operating the pump of the sludge transfer unit 151. By alternately carrying out the above treatment in the two raw water tanks 110, a predetermined amount of liquid is always stored in the treated water tank 120, and subsequent continuous treatment can be carried out efficiently.

[0020] The liquid components stored in the treated water tank 120 are transferred to the first filtration tank 130 by a pump in the first treated water transfer unit 131 . At this time, it is desirable to take water from 500 mm above the bottom of the treatment tank 120 so that even if a small amount of remaining solid components settle at the bottom of the treatment tank 120 as sludge, they will not be mixed in. It is also desirable to transfer the sludge that has settled at the bottom of the treated water tank 120 to the sludge tank 150 as maintenance about twice a year. The liquid component that has passed through the first filtration tank 130 is transferred to the second filtration tank 140 by a pump in the second treated water transfer unit 141 . The liquid components discharged from the second filtration tank 140 have a significantly reduced BOD value, and furthermore, the liquid components that pass through the second filtration tank 140 are transferred to the decolorization treatment tank 160 by the pump of the decolorization treatment water transfer unit 161. The treated water discharged from the decolorization treatment tank 160 has been sufficiently reduced in color, and the water can be reused as washing water for the parlor in the cowshed, or can be discharged as is.

[0021] The results of processing in this embodiment are shown below. [Table 1]

[0022] As can be seen from the table above, by passing through the first filtration tank 130, the BOD (biochemical oxygen demand), COD (chemical oxygen demand), SS (suspended solids), and phosphorus are all reduced to values ​​below the general wastewater standards set by the Ministry of the Environment in accordance with the Water Pollution Control Act, and by passing through the second filtration tank 140, the SS and phosphorus are further reduced.

[0023] A specific flow of treatment when treating wastewater discharged from a parlor in a cowshed (a place where milk is taken out) using the wastewater treatment system 100 configured as above will be described. The capacity of each tank is as follows: Raw water tank ···Approx. 35m 3 *2 1st filtration tank ···Approx. 40m 3 *2 2nd filtration tank ·Approx. 40m 3 Treatment tank: Approx. 90m 3 Decolorization treatment tank: Approx. 40m 3 In addition, rice husk activated carbon was used as the decolorizing material for the first decolorizing treatment layer 162a, rice husk activated carbon processed into pellets with a diameter of 8 mm was used as the decolorizing material for the second decolorizing treatment layer 162b, and activated carbon made from food waste was used as the decolorizing material for the third decolorizing treatment layer 162c. As the support member 163, a punched metal plate having a large number of through holes with a diameter of 1 mm was used.

[0024] The liquid component that has passed through the second filtration tank 140 is transferred to the decolorization treatment tank 160 by a pump in a decolorization treatment water transfer unit 161 . At this time, the treated water discharged from the second filtration tank 140 has a significantly reduced SS value, etc., which prevents clogging of the decolorization treatment layer 162, enables decolorization treatment to be carried out efficiently in a short time, and reduces operating costs. Furthermore, the frequency of replacing the decolorizing treatment material can be reduced, and the equipment costs can be reduced.

[0025] The liquid components transferred to the decolorization treatment tank 160 and showered onto the upper surface of the first decolorization treatment layer 162a pass through the first decolorization treatment layer 162a and are decolorized by the decolorization treatment material, and then pass through the through holes provided in the first support member 163a and are introduced onto the upper surface of the second decolorization treatment layer 162b. The liquid component introduced onto the upper surface of the second bleaching treatment layer 162b passes through the second bleaching treatment layer 162b and is bleached by the bleaching treatment material, and then passes through the through hole provided in the second support member 163b and is introduced onto the upper surface of the third bleaching treatment layer 162c. The liquid component introduced onto the upper surface of the third bleaching treatment layer 162c passes through the third bleaching treatment layer 162c and is bleached by the bleaching treatment material, and then passes through a through hole provided in the third support member 163c and is introduced into the bottom piping 165. The treated water discharged from the decolorization treatment tank 160 has been sufficiently reduced in color, and the water can be reused as washing water for the parlor in the cowshed, or can be discharged as is.

[0026] FIG. 3 shows photographs of the appearance of wastewater treated in this embodiment after passing through the first filtration tank 130, the second filtration tank 140, and the decolorization treatment tank 160. As can be seen from FIG. 3, passing the treated water through the decolorization treatment tank 160 can sufficiently reduce the yellowish-brown coloration that remained in the treated water after passing through the second treatment tank 140.

[0027] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design modifications can be made without departing from the present invention as set forth in the claims. The wastewater treatment system according to the present invention has a total of three decolorizing treatment layers 162, but the number of decolorizing treatment layers 162 is not limited to three, and one to two layers or four or more layers may be provided. Furthermore, in the above-described embodiment, the first bleaching treatment layer 162a, the second bleaching treatment layer 162b, and the third bleaching treatment layer 162c all have the same volume, but the attachment position of the support member 163 may be changed to change the volume of the bleaching treatment layer 162 as appropriate. In addition, in the above-described embodiment, rice husk activated carbon is used as the decolorizing treatment material for the first decolorizing treatment layer 162a, rice husk activated carbon processed into pellets with a diameter of 8 mm is used as the decolorizing treatment material for the second decolorizing treatment layer 162b, and activated carbon made from food waste is used as the decolorizing treatment material for the third decolorizing treatment layer 162c, but the order of the decolorizing treatment layers through which the wastewater to be decolorized passes may be reversed, and different types of activated carbon may be used as the decolorizing treatment material. [Explanation of symbols]

[0028] 100 ··· Wastewater treatment system 110 Raw water tank 111 ··· Wastewater introduction unit 112 Mixing unit 115 Sludge pit 120 Treatment tank 121 Supernatant transfer unit 130... 1st filtration tank 131 First treated water transfer unit 135 ... bottom piping 140... 2nd filtration tank 145 ... bottom piping 141 Second treated water transfer unit 150 sludge tank 151 Sludge transfer unit 160 Decolorization tank 161 Decolorized water transfer unit 162 Bleaching treatment layer 162a First bleaching treatment layer 162b: Second bleaching treatment layer 162c Third bleaching treatment layer 163 Support member 163a First support member 163b Second support member 163c Third support member 165 ... bottom piping

Claims

1. A wastewater treatment system that separates and purifies wastewater from washings discharged from livestock houses, a treatment tank into which the supernatant component of the wastewater is introduced by a supernatant transfer unit; a first filtration tank into which the supernatant component of the treated water tank is introduced by a first treated water transfer unit; a second filtration tank into which the liquid component that has passed through the first filtration tank is introduced by a second treated water transfer unit; a decolorization treatment tank into which the liquid component that has passed through the second filtration tank is introduced by a decolorization treatment water transfer unit.

2. The wastewater treatment system includes: a plurality of raw water tanks into which wastewater is introduced and where sedimentation separation is performed; a sludge tank into which the sediment components of the raw water tank are introduced by a sludge transfer unit, A wastewater treatment system, wherein the first filtration tank and the second filtration tank have the same filtration material.

3. the bleaching treatment tank has one or more bleaching treatment layers, 2. The wastewater treatment system according to claim 1, wherein at least one of the decolorizing treatment layers contains activated carbon as a decolorizing treatment material.

4. 4. The wastewater treatment system according to claim 3, wherein the decolorizing treatment layer is provided on a plate-shaped support member having through holes.

5. 4. The wastewater treatment system according to claim 3, wherein the activated carbon includes rice husk activated carbon.

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