KR101641710B1 - Batch type waste water treatment system and treating method using the same - Google Patents

Abstract

Provided is a batch type wastewater treatment apparatus which is able to efficiently perform wastewater treatment while simply moving to various places. The wastewater treatment apparatus comprises: a wastewater treatment tank; a motor revolution per minute (rpm) control type decelerator which is installed on a cover, and rotates at least one agitator exposed to the wastewater treatment space; an electrode rod switch which is installed on the cover, and electrically connected to first and second electrode rods located in the wastewater treatment space; and a sludge treatment unit which is coupled to a lower portion of the wastewater treatment space, and includes a sludge filter and a sludge collection tank. The wastewater treatment tank includes: a wastewater treatment space formed inside thereof; a cover formed at an upper portion thereof; a first valve formed at an upper portion thereof; an inlet pipe installed to communicate with the wastewater treatment space; a second valve formed at a lower portion thereof; and an outlet pipe which is installed to communicate with the wastewater treatment space, and has a nozzle having an entrance formed downwards at an end portion of the wastewater treatment tank.

Description

Technical Field [0001] The present invention relates to a batch type wastewater treatment apparatus and a wastewater treatment method using the same,

The present invention relates to a batch wastewater treatment apparatus and a wastewater treatment method using the batch wastewater treatment apparatus. More particularly, the present invention relates to a batch wastewater treatment apparatus and a wastewater treatment method using the batch wastewater treatment apparatus. The present invention relates to a batch type wastewater treatment apparatus and a wastewater treatment method using the same.

To prevent environmental pollution, large-sized factories have installed and operate large-scale wastewater treatment facilities. Such a large-scale wastewater treatment apparatus comprises an individually manufactured mixing tank, a flocculating tank and a settling tank. For example, as shown in Fig. 6, a conventional large-scale wastewater treatment apparatus includes a low-water tank 1 for storing wastewater and submerging suspended solids, and a sedimentation tank 3 for inducing flocculation of sediment An agglomeration tank 2 and a sedimentation tank 4 for precipitating sludge.

At this time, the pollutants precipitated like the sludge are discharged downward from the sedimentation tank 4, dried and treated in the drying facility 5, and the purified hydrofluoric acid disposed in the upper part of the sedimentation tank 4 is discharged into the discharge tank 7 .

On the other hand, in places where the amount of wastewater generated is relatively small compared to large factories such as a car wash or a small factory, not only the amount of wastewater generated is small, but also the occurrence time is not constant. Therefore, it is difficult to control the flow rate when a large scale wastewater treatment apparatus used in a large factory is used.

In addition, a large-scale wastewater treatment apparatus is performed by a continuous treatment process, which is always operated. When such a large-scale wastewater treatment apparatus continuous treatment process is introduced where the small-scale wastewater occurs, The sedimentation property is deteriorated, and the purification treatment is not properly performed, and thus, the purified water quality may be defective.

In addition, since the conventional large-scale wastewater treatment apparatus has a large volume, it requires a large space and a large number of auxiliary facilities are required, resulting in an excessive initial installation cost and maintenance cost. In addition, a small-sized factory has a plurality of small-sized facilities in a factory, and when a wastewater treatment device is installed for each facility, a problem of cost increase arises.

Korean Patent Publication No. 10-2005-0034761 Korean Registered Utility Model No. 20-0235044

It is an object of the present invention to provide a single wastewater treatment tank by unifying a mixing tank, a flocculation tank and a settling tank so as to facilitate the flow rate control while reducing the volume of the apparatus, Type wastewater treatment apparatus and a wastewater treatment method using the same.

It is also an object of the present invention to provide a batch type wastewater treatment apparatus that can be used while being easily moved.

In one aspect of the present invention, there is provided a wastewater treatment device comprising: a wastewater treatment space formed on an inner side thereof; a cover provided on an upper end thereof; an inlet pipe provided with a first valve at an upper portion thereof and communicating with the wastewater treatment space; A waste water treatment tank communicating with the treatment space, the waste water treatment tank including a nozzle having a downwardly directed inlet at an end thereof; A motor and a rotation speed control type speed reducer installed on the lid to rotate at least one stirrer exposed to the wastewater treatment space; An electrode rod switch installed on the cover and electrically connected to the first and second electrode rods located in the wastewater treatment space; A sludge treatment unit coupled to a lower portion of the wastewater treatment tank and including a sludge filter and a sludge collecting tank; And a waste water treatment device for treating waste water.

According to a preferred aspect of the present invention, the lower part of the wastewater treatment tank has a tapered shape, and the lower center part can have a space for collecting the sludge.

According to a preferred aspect of the present invention, the lower part of the wastewater treatment tank has a tapered shape, and the lower center part can have a space for collecting the sludge.

According to a preferred feature of the present invention, at least one cleaning nozzle installed inside the upper side of the wastewater treatment tank; A circulation pipe provided so as to communicate with a portion having a tapered shape of the wastewater treatment tank; And a circulation pump for supplying the wash water accommodated in the wastewater treatment tank to the wash exhaust through the circulation pipe; As shown in FIG.

According to a preferred aspect of the present invention, at least one cleaning nozzle installed on the cover to face the wall surface of the wastewater treatment tank; A corrugating pipe connecting the outlet pipe and the cleaning nozzle; And an outlet brine pump for supplying the brine discharged from the outlet pipe to the cleaning nozzle through the outlet brine pipe. As shown in FIG.

According to a preferred feature of the present invention, a waste water reservoir; An inlet pipe connecting the inlet pipe and the waste water storage tank; And a filter built-in pump installed inside the inflow pipe; As shown in FIG.

According to a preferred aspect of the present invention, the first electrode rod may be longer than the second electrode rod, and the first electrode rod may have a length extending from the cover to the outlet pipe.

According to a preferred aspect of the present invention, the first electrode rod is formed longer than the second electrode bar, and the second electrode bar has a length extending from the cover to the inflow pipe.

In an embodiment of the present invention, the apparatus further comprises a support leg supporting the wastewater treatment tank, the support leg having an anchor and an adjustment plate at a lower end thereof.

In another embodiment of the present invention, the apparatus further includes a support leg supporting the wastewater treatment tank, wherein the support leg can be provided with a movable wheel at a lower end thereof.

According to another aspect of the present invention, there is provided a method of treating a wastewater, comprising: introducing wastewater into an wastewater treatment tank through an inflow pipe until a surface of the wastewater reaches a second electrode; Mixing the introduced wastewater by rotating at a high speed of 170 to 190 RPM using a stirrer; Agglomerating the sludge by rotating the mixed wastewater at a low speed of 50 to 70 RPM in a speed-reducing speed reducer; Dewatering the sludge agglomerated wastewater for 2 to 3 hours to settle the sludge; And discharging the supernatant through the outflow tube until the water surface is spaced from the first electrode rod; The present invention also provides a method for treating a batch wastewater.

According to a preferred aspect of the present invention, the step of discharging the supernatant may be performed, and then the precipitated sludge may be discharged to the sludge treatment unit through the sludge discharge pipe and removed from the filter.

According to the present invention, since the mixing, coagulation, and settling tank can be unified into one unit, the mixing process, the coagulation process, and the settling process can be performed in one unit, so that the volume of the unit can be reduced, It is possible to dispose a batch type wastewater treatment in which the amount of generated wastewater is not constant or a small amount is installed and the flow rate is easily adjusted and the wastewater is treated once every predetermined amount.

Further, a movable means is provided at the lower part, and a wrinkle pipe having a filter with a built-in filter is installed in the wastewater treatment tank, so that wastewater treatment can be efficiently performed while easily moving the place if necessary.

1 is a cross-sectional view schematically showing a wastewater treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing the installation of an inflow pipe having a filter with a built-in filter in FIG.
FIG. 3 is a cross-sectional view schematically showing a circulation device and a cleaning nozzle installed in FIG.
FIG. 4 is a cross-sectional view schematically showing an outflow tube connected to an outflow tube and a cleaning nozzle in FIG. 2.
Fig. 5 is a plan view schematically showing a cleaning nozzle installed on the lid.
6 is a schematic view showing a conventional large scale wastewater treatment apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the following embodiments.

The embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements. In the drawings, like reference numerals are used throughout the drawings.

In addition, to include an element throughout the specification does not exclude other elements unless specifically stated otherwise, but may include other elements.

1 is a cross-sectional view schematically showing a wastewater treatment apparatus according to an embodiment of the present invention.

1, a wastewater treatment apparatus 10 according to an embodiment of the present invention includes a wastewater treatment tank 11 having a wastewater treatment space 14 in which a wastewater treatment process is performed, and a sludge treatment unit 70, .

The upper part of the wastewater treatment tank 11 is cylindrical, and the lower part is conical.

In the wastewater treatment tank 11, an inflow pipe 21 may be connected to the upper portion and an outflow pipe 31 may be connected to the lower portion.

An inflow pipe (21) installed on the upper part of the cylindrical portion of the wastewater treatment tank (11) serves to inflow wastewater to be wastewater treated in the wastewater treatment tank (11). A first valve 22 is provided in the inflow pipe 21 and the first valve 22 is controlled to be opened and closed through electronic control by the first valve regulator 23 so that the inflow Thereby controlling the amount of wastewater. For example, when the water surface of the wastewater contained in the wastewater treatment space 14 touches the second electrode rod 63 to be described later, the first valve regulator 23 closes the first valve 22 to block the inflow of the wastewater .

An outflow pipe (31) installed at the lower part of the cylindrical portion of the wastewater treatment tank (11) serves to discharge the supernatant obtained through chemical treatment and sludge settling to the outside. Here, supersonic water means water for which wastewater treatment has been completed. A second valve 32 is provided in the outflow pipe 31 and the second valve 32 is opened and closed by electronic control by the second valve regulator 33 so that the upper water is supplied to the outlet pipe 33 To determine whether or not to discharge it. For example, since the sedimentation process of the sludge takes a certain time, the second valve regulator (33) opens the second valve (32) after a certain period of time after closing the second valve in consideration of this time, . A nozzle 34 having an inlet in a downward direction may be formed at the inlet of the outlet pipe 31. The nozzle (34) is directed downward so that the sludge settled can be prevented from flowing into the nozzle (34).

A lid 41 may be formed on the upper portion of the wastewater treatment tank 11 and the lid 41 may be fixed by the lid fixing portion 42. The lid 41 is provided with a motor for rotating the agitator 53 and a speed reducer 51 for controlling the number of revolutions. The motor and rotation speed control type speed reducer 51 rotates the agitator 53 through the agitating shaft 52 and rotates the operation of the agitator 53 at high speed rotation (170 to 190 RPM) or low speed rotation To 70 RPM). At this time, at least one stirrer 53 may be provided, and a plurality of stirrers 53 may be provided.

Since the necessary facilities such as the motor are all attached to the lid 41, the lid 41 can be separated as necessary to easily repair facilities such as a motor, and the maintenance of the wastewater treatment tank can be facilitated.

The lid 41 may be provided with an electrode rod switch 61 capable of measuring the level of wastewater under processing in the wastewater treatment tank 11. The electrode rod switch 61 may be connected to the first electrode rod 62 and the second electrode rod 63 having different lengths from each other.

The first and second electrode rods 62 and 63 extend from the lid 41 to the inside of the wastewater treatment tank 11. For example, the first electrode rod 62 may be longer than the second electrode rod 63 and the first electrode rod 62 may extend in the height direction from the lid 41 to the lower end of the inlet of the outlet pipe 31 And the second electrode rod 63 may extend from the lid 41 in the height direction to the lower end of the outlet of the inflow pipe 21.

That is, the first electrode rod 62 may have a length extending from the lid 41 to the outlet pipe 31, and the second electrode rod 63 may have a length extending from the lid 41 to the inlet pipe 21 Lt; / RTI >

At least one or more chemical injection pipes are installed in the lid 41 so that necessary medicines can be injected in accordance with the wastewater treatment step. In this case, when two chemical injection pipes are provided, the first and second dosing pumps The first and second water treatment chemical injection pipes 102, 103, 105, and 106 provided with the first and second water treatment chemical injection pipes 101 and 104 are disposed.

The first and second water treatment chemical injection pipes 102, 103, 105, and 106 are connected to the first and second water treatment chemicals reservoirs 107 and 108 to inject medicines necessary for the mixing process and the coagulation process .

The wastewater treatment tank (11) is provided with a support leg (15) for supporting the wastewater treatment tank (11) at the lower outer side. An anchor 17 and an adjusting plate 16 may be formed at the lower end of the supporting leg 15. The wastewater treatment apparatus of this embodiment is of a small size so that the wheels 18 can be installed instead of the anchors 17 and the adjustment plate 16 as shown in Figures 2 and 3, And can be manufactured to enable wastewater treatment.

The lower portion 12 of the wastewater treatment tank may have a tapered shape. That is, since the lower portion 12 of the waste water treatment tank is formed in a hollow shape having a hole in its center portion, it can collect the sludge generated in the wastewater treatment process toward the hole in the central portion.

A sludge receiving space 14a is present in a lower center portion of the wastewater treatment tank 11 and can be used as a place for collecting sludge to discharge the sludge generated during the wastewater treatment process to the sludge discharge pipe 81.

After discharging the supernatant, the sludge is discharged to the sludge treatment unit 70 through the sludge discharge pipe 81. At this time, the sludge outflow pipe 81 may be provided with a sludge outflow valve 82 and a sludge outflow valve regulator 83 for controlling the sludge outflow valve 82. For example, the sludge outflow valve regulator 83 can open the sludge outflow valve 82 to discharge the sludge when the first electrode rod 62 and the water surface of the wastewater are separated.

The sludge treatment section (70) is disposed below the wastewater treatment tank (11). The sludge treatment section 70 may have a structure in which the sludge collecting tank 72 is fixed to the lower part of the wastewater treatment tank 11 by the fixing section 71. At this time, the sludge filter 74 is disposed in the sludge collecting tank 72, the sludge discharged from the sludge discharge pipe 81 is removed from the sludge filter 74, and the other water is removed from the sludge collecting part 75). Then, the water collected in the sludge collecting part (75) flows into the inflow pipe (21) together with the wastewater to be treated through the collecting water pipe (73). When a certain amount of sludge collects in the sludge collecting tank 72, the sludge collecting tank 72 is separated to remove the sludge, and then the sludge collecting tank 72 is installed in the sludge receiving unit 71 again. That is, the sludge collecting tank 72 is a structure that can be coupled to and separated from the waste water treatment tank.

The wastewater treatment apparatus 10 according to an embodiment of the present invention can sequentially perform the mixing process, the coagulation process, and the settling process in the wastewater treatment tank 11, so that a separate mixing tank, The installation area of the wastewater treatment device 1 can be reduced. Further, since the wastewater treatment is performed in one wastewater treatment tank 11, there is an advantage that a small amount of wastewater can be effectively treated.

FIG. 2 is a cross-sectional view schematically showing a corrugated pipe having a filter with a built-in filter installed therein.

Referring to FIG. 2, the wastewater treatment apparatus of the present embodiment collects wastewater requiring treatment in a wastewater storage tank 200, and when a certain amount of wastewater is collected, wastewater flows into the inflow pipe 91 through a corrugated pipe 91 . At this time, a filter built-in pump 92 may be installed inside or at one end of the inflow pipe 91. The filter built-in pump 92 pumps wastewater contained in the wastewater storage tank 200 and sends it to the wastewater treatment tank 11 while blocking a large mass of contaminants present in the wastewater.

Further, the wastewater treatment apparatus 1 of the present embodiment is small in size, so that the wheel 18 can be installed on the support leg 15. As described above, when the wheel 18 is mounted on the lower part, it can be easily moved and useful for each facility. On the other hand, if the wastewater storage tank is installed in a facility such as a container and a plurality of wheels are installed at the bottom of the container, the movement can be made easier.

FIG. 3 is a cross-sectional view schematically showing the circulation device and the cleaning nozzle installed in FIG. 2, FIG. 4 is a cross-sectional view schematically showing the outflow tube connected to the outflow tube and the cleaning nozzle, 5 is a plan view schematically showing that a lid is provided with a cleaning nozzle.

Referring to FIG. 3, the upper lid 41 may be provided with a cleaning nozzle 114. The cleaning nozzle 114 is configured to spray water with a strong water pressure. Water is sprayed into the empty wastewater treatment space 14 after the wastewater treatment to remove the foreign matter on the inner wall surface of the wastewater treatment tank 11 .

Referring to FIG. 5, the cleaning nozzle 114 may be installed on the upper cover 41 to spray water with a strong water pressure toward the wall surface of the wastewater treatment tank 11. At least one or more cleaning nozzles 114 may be installed along the periphery of the upper cover 41. Each of the cleaning nozzles 114 may include a washing water distribution pipe 115 installed inside the upper cover 41 . The washing water distributing pipe 115 is provided with a washing water inflow portion 116 through which the washing water flows into the washing water inflow portion 116. The washing water inflow portion 116 is connected to the circulating facility 111 or the outflow tube 93, 114).

A circulation pipe 112 and a circulation pump 113 may be installed in the waste water treatment tank 11 as a circulation facility 111. As described above, when cleaning is performed by the cleaning nozzle 114, the water used for cleaning may be partially filled in the wastewater treatment space 14, which is pumped by the circulation pump 113 to the circulation pipe 112 And is supplied to the cleaning nozzle 114 again for use. Thus, the amount of water used for cleaning can be reduced.

4, the discharge pipe 31 and the cleaning nozzle 114 are connected to each other by an outflow tube 93 instead of a separate circulation system as a method of supplying washing water to the cleaning nozzle 114 Cleaning water can be supplied to the cleaning nozzle 114.

At this time, an outflow pipe 94 may be installed in the outflow pipe 93. When cleaning is performed by the cleaning nozzle 114, the water used for cleaning may be partially filled in the wastewater treatment space 14, which is pumped by the outlet brine pump 94, And is supplied to the cleaning nozzle 114 again for use, so that the amount of water used for cleaning can be reduced.

Hereinafter, a method of performing wastewater treatment using the wastewater treatment apparatus 10 described above will be described.

First, the wastewater flows into the wastewater treatment tank 11 through the inflow pipe 21 until the water surface reaches the second electrode rod 63. At this time, when the inflow wastewater contacts the second electrode rod 63, the inflow valve electronic regulator 23 closes the inflow valve 22. Thereafter, when the inflow process is completed, the introduced wastewater is mixed at a high rotation speed of 170 to 190 RPM using an agitator 53. At this time, during the mixing process, the first dosing pump 101 is operated to inject the medicines necessary for wastewater treatment, and the agitator 53 is rotated at a high speed to perform the mixing process, Can be improved.

Next, the mixed wastewater is agglomerated while allowing the speed control type speed reducer to rotate at a low speed of 50 to 70 RPM. At this time, the second dosing pump 104 may be operated during the coagulation process to inject medicines necessary for wastewater treatment. As described above, when the agitator 53 is rotated at low speed and agglomerates the sludge, the grain growth of the sludge can be induced.

Next, the wastewater that has undergone agglomeration is allowed to stand for 2 to 3 hours to precipitate the sludge. At this time, in the settling process, the sludge flows on the tapered portion of the lower portion 12 of the wastewater treatment portion 11 to the central portion 13 of the lower portion of the wastewater treatment tank 11 and collects in the sludge receiving space 14a .

Next, when the sludge is collected in the sludge receiving space 14a, the supernatant is drained through the outflow pipe 31 until the water surface is separated from the first electrode rod 62. That is, when the agitator 53 is stopped and after 2 to 3 hours, the second valve regulator 33 opens the second valve 32 to discharge the supernatant, and the water level in the wastewater treatment device 10 is lowered, And closes the second valve 32 for controlling the opening and closing of the outlet pipe 31 when the first valve 32 is separated from the one electrode rod 62.

Next, after the supernatant is drained, the precipitated slurry is drained to the sludge treatment unit 70 through the slurry effluent pipe 81. The sludge discharge valve regulator 83 opens the sludge discharge valve 82 to discharge the sludge when the water level in the wastewater treatment device 1 is lowered and the water surface is separated from the first electrode rod 62. Thereafter, the discharged sludge is removed from the sludge filter 74, and the other water collects in the sludge collecting part 75 of the sludge collecting tank 72 and flows back into the waste water storage tank 200 and the like.

The present invention is not limited to the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

1: Wastewater treatment device 11: Wastewater treatment tank
14: wastewater treatment space 14a: sludge receiving space
15: pedestal 16: regulating plate
17: Anchor 18: Wheel
21: inlet pipe 22: first valve
23: inlet valve regulator
31: outlet pipe 32: second valve
33: outlet valve regulator 34: nozzle
41: lid 42: lid fixing part
51: Motor and Reducer Controlled Type Reducer
52: stirring shaft 53: stirrer
61: Electrode switch 62: First electrode
63: second electrode
70: sludge treatment unit 71:
72: Sludge collecting tank 73: House water pipe
74: Sludge filter 75: Sludge collecting part
81: sludge outflow pipe 82: sludge outflow valve
83: Sludge outflow valve regulator
91: inlet pipe 92: filter with built-in pump
93; Outflow tube 94; Pump
101: first metering pump 102, 103: first water treatment chemical injection tube
104: second metering pump 105, 106: second water treatment chemical injection tube
107: First water treatment chemical storage tank
108; The second water treatment agent reservoir
111: circulation device 112: circulation pipe
113: Circulating pump 114: Cleaning nozzle

Claims (6)

And an upper portion is cylindrical and has a lower portion and a lower portion. The lower portion of the cylindrical portion has a first valve, an inlet pipe communicating with the wastewater treatment space, and a lower portion of a cylindrical shape A waste water treatment tank having a second valve and provided with a nozzle communicating with the wastewater treatment space and having a downwardly directed inlet at an end thereof;
A motor and a rotation speed control type speed reducer installed on the lid to rotate at least one stirrer exposed to the wastewater treatment space;
An electrode rod switch installed on the cover and electrically connected to the first and second electrode rods located in the wastewater treatment space;
A sludge treatment unit including a sludge filter and a sludge collecting tank, the sludge treating unit being connectable and detachable to a lower part of the wastewater treatment tank;
A support leg supporting the wastewater treatment tank and provided with a movable wheel at a lower end thereof;
A wash water distribution pipe spaced inwardly from the periphery of the lid bottom and installed along the periphery;
A plurality of cleaning nozzles installed on the wash water distribution pipe so as to face the inner wall surface of the wastewater treatment tank to spray foreign matter on the inner wall surface by spraying water on the inner wall surface of the wastewater treatment tank; And
A wash water inflow portion communicating with the wash water distribution pipe;
A circulation pipe connecting the lower portion of the wastewater treatment tank and the wash water inflow portion; And
A circulation pump installed in the circulation pipe to pump the water to be filled into the wastewater treatment tank when the wastewater treatment tank is cleaned by the cleaning nozzle and supply the water to the wash water inflow portion again; , ≪ / RTI &
Wherein a portion of the circulation pipe connected to the wastewater treatment tank is a lower portion of the effluent pipe and is a pointed portion of the wastewater treatment tank,
Wherein the first electrode bar is longer than the second electrode bar and the first electrode bar has a length extending from the cover to the outlet pipe,
Wherein the second electrode rod has a length extending from the lid to the inlet pipe. The method according to claim 1,
Waste water reservoir; An inlet pipe connecting the inlet pipe and the waste water storage tank; And a filter built-in pump installed inside the inflow pipe; Further comprising a plurality of wastewater treatment units. delete delete A wastewater treatment method for treating wastewater using a batch wastewater treatment apparatus according to any one of claims 1 to 3,
Introducing the wastewater into the wastewater treatment tank through the inflow pipe until the water surface reaches the second electrode rod;
Mixing the introduced wastewater by rotating at a high speed of 170 to 190 RPM using a stirrer;
Agglomerating the sludge by rotating the mixed wastewater at a low speed of 50 to 70 RPM in a speed-reducing speed reducer;
Dewatering the sludge agglomerated wastewater for 2 to 3 hours to settle the sludge; And
Flowing the supernatant through the outflow tube until the water surface is separated from the first electrode rod; ≪ / RTI > 6. The method of claim 5, further comprising: discharging the supernatant; flowing the precipitated sludge through a sludge discharge pipe to a sludge treatment unit and removing the sludge from the filter; Wherein the waste water treatment method further comprises:

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