AU2016210227B2

AU2016210227B2 - Water treatment device

Info

Publication number: AU2016210227B2
Application number: AU2016210227A
Authority: AU
Inventors: Tsuyoshi Ichinari; Shinichi Mizuno; Jun Togari
Original assignee: Fujiclean Co Ltd
Current assignee: Fujiclean Co Ltd
Priority date: 2015-01-20
Filing date: 2016-01-19
Publication date: 2020-09-17
Anticipated expiration: 2036-01-19
Also published as: AU2016210227A1; JP6657524B2; JP2016131940A; WO2016117576A1

Abstract

[Problem] To provide a technique for efficient treatment of water to be treated. [Solution] A treatment tank unit 101 of this water treatment device 100 is equipped with a settling separation tank 120, an anaerobic treatment tank 140, an aerobic treatment tank 150, a treatment water tank 160, and a disinfection tank 170. A third airlift pump 182 for feeding water to be treated in the treatment water tank 160 to the disinfection tank 170 is provided. In so doing, it is possible for water levels in the settling separation tank 120, the anaerobic treatment tank 140, the aerobic treatment tank 150, and the treatment water tank 160 to fluctuate at identical water levels. Further, a first airlift pump 180 feeds water to be treated in the anaerobic treatment tank 140 to the settling separation tank 120, and a second airlift pump 181 feeds water to be treated from the aerobic treatment tank 150 to the settling separation tank 120. In so doing, the water to be treated is circulated through the settling separation tank 120, the anaerobic treatment tank 140, the aerobic treatment tank 150, and the treatment water tank 160.

Description

FJC1501 AU10

WATER TREATMENT DEVICE TECHNICAL FIELD

[0001]

The present invention relates to a water treatment apparatus for treating sewage such as

domestic wastewater.

BACKGROUND ART

[0002]

[0 A reference herein to a patent document or other matter which is given as prior art is not

to be taken as an admission that that document or matter was known or that the information it

contains was part of the common general knowledge as at the priority date of any of the claims.

[0002a]

Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this

L5 specification (including the claims) they are to be interpreted as specifying the presence of the

stated features, integers, steps or components, but not precluding the presence of one or more other

features, integers, steps or components, or group thereto.

[0002b]

Japanese laid-open patent publication No. 2000-197892 discloses a septic tank having a

first anaerobic filter bed tank, a second anaerobic filter bed tank, a carrier fluidized tank, a

sedimentation tank and a disinfecting tank. It is configured such that water to be treated flows

through each of the tanks by spontaneous flow.

SUMMARY OF THE INVENTION

[0003]

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Generally, in a septic tank having an anaerobic treatment tank for anaerobically treating

water to be treated and an aerobic treatment tank for aerobically treating water to be treated on a

downstream side of the anaerobic treatment tank, efficiency of treating water to be treated may

decrease when a lot of sludge is deposited (precipitated) particularly in the aerobic treatment tank.

Therefore, it is desired that sludge which flows from the anaerobic treatment tank into the aerobic

treatment tank and sludge generated in the aerobic treatment tank are efficiently transferred to a

different tank from the aerobic treatment tank to store sludge.

[0004]

The above-described septic tank is configured such that water to be treated flows

[0 through each of the tanks by spontaneous flow, so that the same amount of treated water as

wastewater introduced into the septic tank is discharged from the septic tank. This septic tank is

configures such that water to be treated is circulated by air lift pumps provided in the second

anaerobic filter bed tank and the carrier fluidized tank, and sludge deposited in the tanks is

returned to the first anaerobic filter bed tank, while the water levels of thefirst anaerobic filter bed

[5 tank, the second anaerobic filter bed tank and the carrierfluidized tank are always kept constant.

Therefore, the lifting height of each of the air lift pumps for returning sludge and water to be

treated does not change. In other words, the amount of water to be returned by the air lift pumps

does not change. When the amount of water to be returned by the air lift pumps is small, the

efficiency of returning sludge may decrease. Further, when the amount of water to be returned by

the air lift pumps is large, the flow velocity in the tanks rises, so that sludge to be returned cannot

be sufficiently precipitated down to the vicinities of inlet ports of the air lift pumps. As a result, the

efficiency of returning sludge may decrease. In order to efficiently return sludge in such a septic

tank as described above in which the water level is kept constant, it is necessary to change the

amount of water to be returned by the air lift pumps. Specifically, the amount of water to be returned by the air lift pumps is set small in order to efficiently precipitate sludge in the tanks, and then temporarily increased to efficiently return the sludge. In order to change the amount of water to be returned by the air lift pumps in the above-described septic tank, it is necessary to change the air volume of a blower and thus to provide an air volume control mechanism of the blower. Accordingly, it is desirable to provide a water treatment apparatus having a circulation device for circulating water to be treated and transferring sludge, with a technique for efficiently transferring sludge together with water to be treated according to the level of the water by the circulation device.

[0005] According to the present invention there is provided a water treatment apparatus for treating water to be treated containing sludge, comprising: an inflow tank into which water to be treated is introduced, an anaerobic treatment tank which is disposed on a downstream side of the inflow tank and anaerobically treats water to be treated, an aerobic treatment tank which is disposed on a downstream side of the anaerobic treatment tank and aerobically treats water to be treated, a water discharging transfer device for transferring treated water in order to discharge the treated water out of the water treatment apparatus, a first circulation device for transferring water to be treated from the anaerobic treatment tank to the inflow tank to circulate the water, a second !0 circulation device for transferring water to be treated from the aerobic treatment tank to the inflow tank to circulate the water, the first circulation device includes a first air lift pump to transfer the sludge deposited close to the bottoms of the anaerobic treatment tank to the inflow tank together with the water to be treated, the second circulation device includes a second air lift pump to transfer the sludge deposited close to the bottoms of the aerobic treatment tank to the inflow tank together with the water to be treated, the aerobic treatment tank is provided as a single chamber, in which aerobic filter media is disposed for aerobic treatment of the water to be treated and the water to be treated is transferred by downward flow, the treated water tank is provided such that the water to be treated is transferred by upward flow in the treated water tank, the aerobic filter media is defined by a fixed filter bed fixed to the water treatment apparatus, wherein levels of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic treatment tank fluctuate at the same level. According to a preferred aspect of the present invention, a water treatment apparatus for treating water to be treated containing sludge is provided. The water treatment apparatus has an inflow tank, an anaerobic treatment tank, an aerobic treatment tank, a water discharging transfer device for discharging treated water, a first circulation device and a second circulation device. Water to be treated is introduced into the inflow tank and then treated in the anaerobic treatment tank and the aerobic treatment tank in sequence. The water discharging transfer device is provided to transfer treated water in order to discharge the treated water. The water discharging transfer device is preferably provided to discharge the water which has been aerobically treated in the aerobic treatment tank. Further, the water discharging transfer device may be provided to directly discharge the treated water out of the water treatment apparatus, or to discharge the treated water to a further treatment tank (such as a disinfecting tank) in the water treatment apparatus. The first circulation device transfers the water to be treated from the anaerobic treatment tank to the inflow tank to circulate the water between the inflow tank and the anaerobic treatment tank. The second circulation device transfers the water to be treated from the aerobic treatment tank to the inflow tank to circulate the water among the inflow tank, the anaerobic treatment tank and the aerobic treatment tank. The first and second circulation devices transfer sludge together with the water to be treated. It is configured such that the levels of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic !0 treatment tank fluctuate at the same level. Specifically, the water to be treated can move between the inflow tank and the anaerobic treatment tank and between the anaerobic treatment tank and the aerobic treatment tank. Thus, the levels of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic treatment tank

3a

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fluctuate between a high water level and a low water level.

[0006]

The water discharging transfer device, the first circulation device and the second

circulation device may suitably include an air lift pump, a submerged pump and other various

kinds of pumps. Preferably, the amount of the water to be transferred is varied according to the

level of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic

treatment tank. Specifically, the amount of the water to be transferred is set to be small when the

water level is low, while it is set to be large when the water level is high. When air lift pumps are

used as the water discharging transfer device, the first circulation device and the second circulation

device, the lifting height of each of the air lift pumps automatically fluctuates according to the

level of the water to be treated in the water treatment tanks, so that the amount of the water to be

transferred is varied. Further, it may be configured such that the amount of the water to be

transferred is varied by controlling the amount of air to be supplied to the air lift pumps according

to the level of the water to be treated. Further, when a submerged pump is used as the water

discharging transfer device, the amount of the water to be transferred is varied by controlling

driving and stopping of the submerged pump.

[0007]

According to this invention, by providing the water discharging transfer device for

discharging treated water, the levels of water to be treated in the inflow tank, the anaerobic

treatment tank and the aerobic treatment tank are kept the same and fluctuate at the same level.

Therefore, when wastewater does not flow into the water treatment apparatus from the outside and

treated water is discharged by the water discharging transfer device, the level of water to be treated

in each of the tanks drops to a low level. In this state, by reducing the amount of water to be

transferred by the first and second circulation devices, the flow velocity in the tanks is lowered, so

FJC1501 AU10

that sludge in the water to be treated is efficiently precipitated. When wastewater flows into the

water treatment apparatus from the outside and the water level rises to above the low level, the

amount of sludge which is transferred together with the water to be treated is increased by

increasing the amount of water to be transferred by the first and second circulation devices. As a

result, precipitated sludge in the anaerobic treatment tank and the aerobic treatment tank is

efficiently transferred to the inflow tank. Particularly, by using an air liftpump as at least one of

the first and second circulation devices, without providing a device for controlling the amount of

transfer of the air lift pump, fluctuation of the lifting height of the air lift pump according to

fluctuation of the water level can be utilized to increase the transfer amount of the water to be

treated and sludge as the water level rises. Water to be treated in each tank is efficiently treated by

thus efficiently transferring sludge precipitated in the anaerobic treatment tank and the aerobic

treatment tank to the inflow tank. Thus, the capacity of each tank in the water treatment apparatus

can be reduced. Therefore, the water treatment apparatus can be prevented from being increased

in size.

[0008]

According to a further aspect of the water treatment apparatus in this invention, the

anaerobic treatment tank includes a first chamber in which the water to be treated is transferred by

downward flow and anaerobic filter media for anaerobically treating the water to be treated are

disposed, and a second chamber which is provided on a downstream side of the first chamber and

in which the water to be treated is transferred by upward flow. Further, the aerobic treatment tank

includes a third chamber in which the water to be treated is transferred by downward flow and

aerobic filter media for aerobically treating the water to be treated are disposed, and a fourth

chamber which is provided on a downstream side of the third chamber and in which the water to

be treated is transferred by upward flow.

FJC1501 AU10

[0009]

According to this aspect, water to be treated is transferred by downward flow and treated

by the anaerobic filter media or the aerobic filter media. Therefore, sludge is easily precipitated

after anaerobic treatment or aerobic treatment. Preferably, intake ports of the first and second

circulation devices are provided close to the bottoms of the anaerobic treatment tank and the

aerobic treatment tank, respectively, such that the first and second circulation devices transfer the

precipitated sludge to the inflow tank together with the water to be treated. Thus, the precipitated

sludge is efficiently transferred to the inflow tank by the first and second circulation devices, so

that stable aerobic treatment of the water to be treated is achieved in the aerobic treatment tank.

[0010]

aerobic filter media form a fixed filter bed fixed to the water treatment apparatus. Thefixed filter

bed is fixed so as not to move during aerobic treatment of the water to be treated in the aerobic

treatment tank. Specifically, the fixed filter bed is fixed to a wall which forms the aerobic

treatment tank. Typically, the fixed filter bed is removably attached to the wall. The aerobic filter

media preferably form a three-dimensional net-like body. By providing the fixed filter bed, the

property of sludge in the water to be treated is changed to be easily precipitated. Further, all of the

aerobic filter media may be configured as fixed filter media, or some of the filter media may be

configured as fixed filter media and the other as movable filter media.

[0011]

position of a lower end of an intake port of the water discharging transfer device in the vertical

direction defines a low water level of the water to be treated in the inflow tank, the anaerobic

treatment tank and the aerobic treatment tank. Preferably, a lower end of a communication hole

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for communication between the anaerobic treatment tank and the aerobic treatment tank is

arranged at a lower position than the lower end of the intake port of the water discharging transfer

device, and an upper end of the communication hole is arranged at a higher position than the lower

end of the intake port of the water discharging transfer device. Therefore, the low water level is set

in a middle region of the communication hole for communication between the anaerobic treatment

tank and the aerobic treatment tank. Thus, when the water level of the inflow tank, the anaerobic

treatment tank and the aerobic treatment tank is at the low water level, the water to be treated is

circulated between the anaerobic treatment tank and the aerobic treatment tank through the

communication hole. Therefore, part of sludge flowing downstream from the anaerobic treatment

tank into the aerobic treatment tank and part of sludge generated during aerobic treatment are

returned to the anaerobic treatment tank. Thus, deterioration of the performance of aerobically

treating the water to be treated in the aerobic treatment tank, which may otherwise be caused by

deposition of sludge, is prevented.

EFFECT OF THE INVENTION

[0012]

According to the present invention, in a water treatment apparatus having a circulation

device for circulating water to be treated and transferring sludge, a technique is provided for

efficiently transferring sludge together with water to be treated according to the level of the water

by the circulation device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]

FIG. 1 schematically shows a water treatment apparatus according to a first embodiment

FJC1501 AU10

of the present invention.

FIG. 2 is a flow chart of water to be treated in the water treatment apparatus.

FIG. 3 is a plan sectional view taken along line III-III in FIG. 1.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3.

FIG. 5 is a sectional view taken along line V-V in FIG. 3.

FIG. 6 is a sectional view taken along line VI-VI in FIG. 3.

FIG. 7 is a sectional view showing a third air lift pump in detail.

FIG. 8 schematically shows a water treatment apparatus according to a second

embodiment of the present invention.

FIG. 9 is a flow chart of water to be treated in the water treatment apparatus.

REPRESENTATIVE EMBODIMENT FOR CARRYING OUT THE INVENTION

[0014]

A water treatment apparatus according to a first embodiment of the present invention is

now explained with reference to FIGS. 1 to 7. In embodiments of the present invention, a water

treatment apparatus for receiving and treating raw water (also referred to as "wastewater" or

"water to be treated") discharged from general houses and apartment houses in a water treatment

region is explained.

[0015]

As shown in FIG. 1, a water treatment apparatus 100 has a tank-shaped treatment tank

body 101 which forms an outer shell of the water treatment apparatus 100. As shown in FIGS. 1

and 3, the treatment tank body 101 has a generally rectangular shape in plan view and formed by

side walls 101a, 101b parallel to each other, side walls 10Ic, 101d parallel to each other, a bottom

wall 10 1e and a top wall 101f. The water treatment apparatus 100 is configured to treat domestic

FJC1501 AU10

wastewater (domestic sewage) together with excrement.

[0016]

As shown in FIG. 1, the treatment tank body 101 has an inlet pipe 102, an outlet pipe

103 and a manhole part 104. The inlet pipe 102 is configured as an opening for leading water (raw

water) to be treated into the internal space of the treatment tank body 101. The outlet pipe 103 is

configured as an opening for leading treated water out of the internal space of the treatment tank

body 101. The manhole part 104 is configured as a part for forming a manhole for tank charge,

internal inspection and cleaning.

[0017]

The manhole part 104 side (the upper wall 101f side) of the treatment tank body 101 is

defined as a tank upper side or a tank upper part, and the opposite side (the bottom wall 101e side)

as a tank lower side, a tank lower part or a tank bottom part. The inlet pipe 102 side (the side wall

101c side) of the treatment tank body 101 is defined as an upstream side, and the outlet pipe 103

side (the side wall 101d side) as a downstream side. Further, in FIG. 1, a direction along an

extending surface of the manhole part 104 is defined as a horizontal direction (also referred to as a

tank longitudinal direction), and a direction crossing the horizontal direction as a vertical direction

(also referred to as a tank vertical direction). A direction perpendicular to the paper surface of FIG.

1 (a direction perpendicular to the tank longitudinal direction and the tank vertical direction, or a

vertical direction in FIG. 3) is defined as a tank transverse direction. Arrows shown in FIGS. 1 to

7 indicate a flow of water to be treated.

[0018]

As shown in FIG. 1, in the internal space of the treatment tank body 101, a water

treatment region is formed for performing a predetermined water treatment while storing raw

water led in through the inlet pipe 102. A sedimentation separation tank 120, a cleaning hole 130,

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an anaerobic treatment tank 140, an aerobic treatment tank 150, a treated water tank 160 and a

disinfecting tank 170 are formed in the water treatment region. As shown in FIG. 2, wastewater

led into the treatment tank body 101 (an inflow baffle 110) through the inlet pipe 102 is treated in

the sedimentation separation tank 120, the anaerobic treatment tank 140, the aerobic treatment

tank 150, the treated water tank 160 and the disinfecting tank 170 in sequence, and thereafter

discharged out of the treatment tank body 101 through the outlet pipe 103. Further, it is

configured such that water to be treated circulates between the sedimentation separation tank 120

and the cleaning hole 130 and between the anaerobic treatment tank 140 and the aerobic treatment

tank 150. The water treatment apparatus 100 may be configured as a septic tank which releases

water discharged out of the treatment tank body 101 as it is, or as a water recycling apparatus for

reusing water discharged out of the treatment tank body 101 as water for flushing toilets or

watering.

[0019]

The inflow baffle 110 forms a most upstream region in the water treatment region.

Wastewater led into the inflow baffle 110 through the inlet pipe 102 flows into the sedimentation

separation tank 120. The water is then separated into solid and liquid in the sedimentation

separation tank 120, and a solid component separated from the water is deposited as precipitated

sludge on the bottom of the sedimentation separation tank 120. Wastewater is first led into the

inflow baffle 110 and then indirectly led into the sedimentation separation tank 120, so that sludge

precipitated in the sedimentation separation tank 120 is prevented from being agitated. The

sedimentation separation tank 120 having the inflow baffle 110 is an example embodiment that

corresponds to the "inflow tank" according to this invention.

[0020]

As shown in FIGS. 1 and 3, a partition wall 105 is provided between the sedimentation

FJC1501 AU10

separation tank 120 and the anaerobic treatment tank 140 on the downstream side thereof and

extends in the tank vertical direction. The partition wall 105 is mounted to the side walls 101a,

101b and the bottom wall 101e. As shown in FIG. 4, right and left openings 105a, 105b are

formed in an upper region of the partition wall 105 and provide communication between the

sedimentation separation tank 120 and the anaerobic treatment tank 140. As shown in FIGS. 3 and

4, a division wall 131 for demarcation between the sedimentation separation tank 120 and the

cleaning hole 130 is mounted to the partition wall 105. The division wall 131 is arranged apart

from the side walls 101a, 101b in the tank transverse direction and arranged apart from the side

walls 101c, 101d in the tank longitudinal direction. The cleaning hole 130 is defined by the

division wall 131 on a central region of the partition wall 105 in the tank transverse direction. The

openings 105a, 105b are provided on the left and right sides of the cleaning hole 130, respectively.

[0021]

As shown in FIGS. 1 and 4, a lower end of the division wall 131 is arranged apart from

a bottom (the bottom wall 101e) of the treatment tank body 101 so that a lower region of the

sedimentation separation tank 120 communicates with the cleaning hole 130. Specifically, the

lower end of the division wall 131 forms a lower end opening 130a of the cleaning hole 130, and

the lower end opening 130a is formed apart upward from the bottom wall 101e. Further,anupper

end of the division wall 131 or an upper end opening 130b of the cleaning hole 130 is formed apart

downward from the upper wall 101f. A long meshed filter 132 formed as a draft tube and a first

diffusing pipe 190 extending through the filter 132 are provided in the cleaning hole 130. As

shown in FIG. 4, the first diffusing pipe 190 is arranged in a right region of the cleaning hole 130.

When air is supplied from a lower end of the first diffusing pipe 190 into the cleaning hole 130 via

the lower end opening 130a, upward flow is generated in the right region of the cleaning hole 130,

while downward flow is generated in a left region of the cleaning hole 130. Thus, a swirl flow is

FJC1501 AU10

generated in the cleaning hole 130, so that the water in the cleaning hole 130 is agitated. Therefore,

the cleaning hole 130 is also referred to as an agitation hole for agitating the water to be treated.

[0022]

Air is diffused from the first diffusing pipe 190 and passed through the filter 132, so that

the air is subdivided or fined (into fine bubbles). Sludge deposited on the bottom of the

sedimentation separation tank 120 circulates together with the water to be treated in the cleaning

hole 130 by the swirl flow (upward flow and downward flow). In the cleaning hole 130, sludge is

efficiently aerobically treated by the subdivided air. By fluctuations of the water level in the water

treatment region, the sludge in the cleaning hole 130 and the sludge on the bottom of the

sedimentation separation tank 120 are moved between the cleaning hole 130 and the

sedimentation separation tank 120, so that sludge containing bubbles is supplied into the

sedimentation separation tank 120. As a result, in the sedimentation separation tank 120, sludge

containing bubbles is floated up as scum and stored at a high concentration.

[0023]

As shown in FIG. 3, the water in the sedimentation separation tank 120 is led

downstream to the anaerobic treatment tank 140 through the right and left openings 105a, 105b.

The anaerobic treatment tank 140 is an example embodiment that corresponds to the "anaerobic

treatment tank" according to this invention.

[0024]

As shown in FIGS. 1, 3 and 5, the anaerobic treatment tank 140 has a first anaerobic

chamber 141 and a second anaerobic chamber 142. A partition wall 106 is provided between the

anaerobic treatment tank 140 and the aerobic treatment tank 150 on the downstream side thereof

and extends in the tank vertical direction. As shown in FIG. 3, a division wall 143 for demarcation

between the first anaerobic chamber 141 and the second anaerobic chamber 142 is mounted to a

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front side (upstream side) of the partition wall 106. The second anaerobic chamber 142 is defined

by the division wall 143 on a central region of the partition wall 106 in the tank transverse

direction. As shown in FIG. 5, a lower end of the division wall 143 is arranged apart from a

bottom of the treatment tank body 101, so that a lower region of thefirst anaerobic chamber 141

communicates with the second anaerobic chamber 142. The first anaerobic chamber 141 and the

second anaerobic chamber 142 are example embodiments that correspond to the "first chamber"

and the "second chamber", respectively, according to this invention.

[0025]

Further, as shown in FIG. 3, a division wall 161 for demarcating a region on the

downstream side of the partition wall 106 between the aerobic treatment tank 150 and the treated

water tank 160 is mounted to a rear side (downstream side) of the partition wall 106. The length of

the second anaerobic chamber 142 defined by the division wall 143 in the tank transverse direction

is set to be longer than the length of the treated water tank 160 defined by the division wall 161 in

the tank transverse direction. With this structure, as shown in FIGS. 3, 5 and 6, left and right

openings 106a, 106b for communication between the second anaerobic chamber 142 and the

aerobic treatment tank 150 are formed in the partition wall 106 outside the division wall 161

(outside the treated water tank 160) and inside the division wall 143 (inside the second anaerobic

chamber 142) in the tank transverse direction. The openings 106a, 106b are an example

embodiment that corresponds to the "communication hole" according to this invention.

[0026]

The division walls 143 and 161 are mounted to the partition wall 106, and in this state,

the partition wall 106 is mounted to the treatment tank body 101. Specifically, the partition wall

106 and the division walls 143 and 161 are formed into an assembly. With this structure, in a

process of manufacturing the water treatment apparatus 100, the second anaerobic chamber 142,

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the aerobic treatment tank 150 and the treated water tank 160 are efficiently and easily provided.

[0027]

An anaerobic filter bed 144 is provided in an intermediate region of the first anaerobic

chamber 141 in the tank vertical direction and supported by the treatment tank body 101. The

anaerobic filter bed 144 is filled with a prescribed amount of anaerobic filter media to which

anaerobic microorganisms for anaerobically treating organic pollutant adhere. As the anaerobic

filter media, plate-like filter media and ball-like skeleton filter media may be suitably used. In the

anaerobic filter bed 144, water to be treated is anaerobically treated and filtered, so that BOD

(biochemical oxygen demand) is reduced and SS (suspended solids) is removed.

[0028]

The water that has been anaerobically treated in the first anaerobic chamber 141 is then

led from a lower region of the first anaerobic chamber 141 to a lower region of the second

anaerobic chamber 142 by downward flow generated in the first anaerobic chamber 141, and

flows upward in the second anaerobic chamber 142. Thus, upward flow is generated in the second

anaerobic chamber 142. Thereafter, the water is led from an upper region of the second anaerobic

chamber 142 to the aerobic treatment tank 150 through the opening 106a (or the opening 106b).

[0029]

A first air lift pump 180 is provided in the second anaerobic chamber 142. In the second

anaerobic chamber 142, sludge which has been transferred from the first anaerobic chamber 141 is

deposited, and SS and sludge which have spontaneously returned from the aerobic treatment tank

150 through the opening 106 are precipitated. Through the first air lift pump 180, the sludge

which has been transferred from the first anaerobic chamber 141 and deposited and the SS and

sludge which have spontaneously returned from the aerobic treatment tank 150 are returned to the

inflow baffle 110 together with water to be treated. The first air lift pump 180 is disposed in the

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second anaerobic chamber 142 in which the anaerobic filter bed 144 is not provided. Therefore,

interference between the first air lift pump 180 and the anaerobic filter bed 144 is avoided.

Specifically, the second anaerobic chamber 142 has a function of anaerobically treating the water

to be treated which has flown into the anaerobic treatment tank 140 while allowing the water to

flow downward in the first anaerobic chamber 141, and a function of isolating the first air lift

pump 180 from the anaerobic filter bed 144. The first air lift pump 180 is an example embodiment

that corresponds to the "first circulation device" according to this invention.

[0030]

As shown in FIG. 3, the treated water tank 160 is provided in a central region on the

downstream side of the partition wall 106 in the tank transverse direction. Further, as shown in

FIG. 6, the aerobic treatment tank 150 is configured to have left and right regions which are

provided on the left and right sides of the treated water tank 160 and a lower region via which the

left and right regions communicate with each other. The lower region of the aerobic treatment

tank 150 communicates with the treated water tank 160.

[0031]

As shown in FIG. 6, in the aerobic treatment tank 150, aerobic filter beds 15la, 15lb are

provided to which aerobic microorganisms for aerobically decomposing (aerobically treating)

organic pollutant in the water to be treated adhere. The aerobic filter bed 151a is disposed below

the aerobic filter bed 151b. The aerobic filter bed 151a is formed of net-like rolledfilter media.

Specifically, the net-like rolled filter medium is a net which is formed of wire rods made of resin

such as polypropylene and polyethylene and three-dimensionally entangled with each other, and is

formed into a cylindrical shape having a diameter of about 100 mm and a length of about 100 mm.

Therefore, the aerobic filter bed 151a is formed by filling a prescribed region with a plurality of the

net-like rolled filter media. Further, as the aerobic filter media of the aerobic filter bed 151a,

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net-like, spherical or plate-like filter media, or filter media formed of porous material may be used.

On the other hand, the aerobic filter bed 151b is formed of a block-like (single) filter medium.

Specifically, the block-like filter medium is a net which is formed of wire rods made of resin such

as polypropylene and polyethylene and three-dimensionally entangled with each other, and is

formed in one piece like a block. Thus, the upper aerobic filter bed 15lb serves as a lid to prevent

the filter media of the lower aerobic filter bed 151a from flowing out. The aerobic filter bed 15lb

is held by a net, a plate-like member or other similar holding member supported by the treatment

tank body 101. Further, the aerobic filter medium of the aerobic filter bed 151b may be shaped

otherwise, for example, into a plate-like form, as long as it is formed in one piece.

[0032]

As shown in FIG. 6, a second diffusing pipe 191 is provided in the aerobic treatment

tank 150. Thus, when passing through the aerobic filter bed 151, the water to be treated is

aerobically treated by air supplied from the second diffusing pipe 191. The water which has been

aerobically treated through the aerobic filter beds 151a, 151b is led to the lower region of the

aerobic treatment tank 150.

[0033]

As shown in FIGS. 1 and 6, a second air lift pump 181 is provided in the treated water

tank 160. The second air lift pump 181 extends to below the treated water tank 160. Thus, part of

the water to be transferred from the aerobic treatment tank 150 to the treated water tank 160 is

returned to the inflow baffle 110 through the second air lift pump 181 before transferred to the

treated water tank 160. In this manner, in the water treatment apparatus 100, water to be treated

circulates through the inflow baffle 110, the sedimentation separation tank 120, the anaerobic

treatment tank 140 and the aerobic treatment tank 150. The aerobic treatment tank 150 and the

treated water tank 160 are an example embodiment that corresponds to the "aerobic treatment

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tank" according to this invention. Further, the aerobic treatment tank 150 and the treated water

tank 160 are example embodiments that correspond to the "third chamber" and the "fourth

chamber", respectively, according to this invention. The second air lift pump 181 is an example

embodiment that corresponds to the "second circulation device" according to this invention.

[0034]

As shown in FIGS. 1 and 3, in the treated water tank 160, the disinfecting tank 170 is

defined by a division wall 171 demarcating the treated water tank 160. Further, a third air lift

pump 182 for transferring the water to be treated from the treated water tank 160 to the

disinfecting tank 170 is provided in the treated water tank 160. The third air lift pump 182 is an

example embodiment that corresponds to the "water discharging transfer device" according to this

invention.

[0035]

As shown in FIG. 7, the third air lift pump 182 mainly includes a pump housing 183 and a

partition part 187. The pump housing 183 is a bottomed cylindrical member extending long in the

vertical direction. The pump housing 183 has an inlet port 184, an air supply port 185 and a

discharge port 186.

[0036]

The inlet port 184 is configured as an opening through which water to be treated is

sucked into the pump housing 183. As shown in FIG. 1, a low water level (LWL) of the treated

water tank 160 is defined by the inlet port 184 of the third air lift pump 182 disposed in the treated

water tank 160. The inlet port 184 is an example embodiment that corresponds to the "intake port"

according to this embodiment.

[0037]

The air supply port 185 is connected to an air supply means (not shown). Thus, air is

FJC1501 AU10

supplied into the pump housing 183 through the air supply port 185. The air supply port 185 is

formed below the inlet port 184 in the vertical direction. The discharge port 186 is configured as

an opening through which the water to be treated is discharged out of the pump housing 183 after

flowing through the pump housing 183. The discharge port 186 is formed above the inlet port 184

in the vertical direction.

[0038]

Further, the partition part 187 is a flat partitioning member extending in the extending

direction of the pump housing 183 (the vertical direction). The partition part 187 partitions the

internal space of the pump housing 183 into a first flow passage 183a and a second flow passage

183b. The first flow passage 183a forms a passage on the inlet port 184 side of the partition part

187, while the second flow passage 183b forms a passage on the discharge port 186 side and the

air supply port 185 side of the partition part 187. The partition part 187 is integrally formed with a

lid for closing a top of the pump housing 183.

[0039]

When a prescribed amount of air is supplied through the air supply port 185, the air

flows upward in the second flow passage 183b, so that water to be treated flows upward in the

second flow passage 183b. Thus, water to be treated is sucked in through the inlet port 184 and

flows downward in the first flow passage 183a. Specifically, water to be treated which is sucked

in through the inlet port 184 from the treated water tank 160 flows through the first and second

flow passages 183a, 183b and is discharged into the disinfecting tank 170 through the discharge

port 186.

[0040]

In the disinfecting tank 170, a chemical cartridge (not shown) is provided which isfilled

with a solid disinfectant for disinfecting the water. After disinfected by the disinfectant which has

FJC1501 AU10

dissolved out of the chemical cartridge, the water is discharged out of the treatment tank body 101

through the outlet pipe 103. Further, another tank such as a discharge pump tank having a

discharge pump may be additionally provided on the downstream side of the disinfecting tank

170.

[0041]

The first to third air lift pumps 180 to 182 and the first and second diffusing pipes 190,

191 are connected to an air supply device (not shown), and an air valve is switched to start and

stop air supply. Air valves of the first to third air lift pumps 180 to 182 and the first and second

diffusing pipes 190 and 191 are controlled by a controller (not shown) or by hand.

[0042]

In the water treatment apparatus 100, as shown in FIG. 4, the low water level (LWL) is

set substantially in the middle of the openings 105a, 105b in the vertical direction. Thus, the

openings 105a, 105b extend to below a lower end of the inlet port 184 of the third air lift pump 182.

Further, a high water level (IWL) is set above the openings 105a, 105b. Similarly, as shown in

FIG. 5, the low water level (LWL) is set substantially in the middle of the openings 106a, 106b in

the vertical direction. Thus, the openings 106a, 106b extend to below the lower end of the inlet

port 184 of the third air lift pump 182. The low water level is an example embodiment that

corresponds to the "low water level" according to this invention. Further, the high water level

(IWL) is set above the openings 106a, 106b.

[0043]

As shown in FIG. 1, when water to be treated flows into the water treatment apparatus

100 through the inlet pipe 102, the water level of the sedimentation separation tank 120 rises. At

this time, the water levels of the anaerobic treatment tank 140, the aerobic treatment tank 150 and

the treated water tank 160 which communicate with the sedimentation separation tank 120

FJC1501 AU10

through the openings 105a, 105b and the openings 106a, 106b increase to the same level as the

sedimentation separation tank 120. Thus, the levels of water to be treated in the sedimentation

separation tank 120, the anaerobic treatment tank 140, the aerobic treatment tank 150 and the

treated water tank 160 are kept the same, and in this state, the water levels of these tanks fluctuate

between the low water level and the high water level.

[0044]

Specifically, the third air lift pump 182 transfers the water to be treated from the treated

water tank 160 to the disinfecting tank 170 when the water level is higher than the low water level.

When the water level of the disinfecting tank 170 is higher than the outlet pipe 103, the water

treated in the disinfecting tank 170 is discharged out of the treatment tank body 101. By this water

transfer of the third air lift pump 182, the water levels in the sedimentation separation tank 120, the

anaerobic treatment tank 140, the aerobic treatment tank 150 and the treated water tank 160 are

lowered to the low water level. At the low water level, water to be treated is not sucked by the

third air lift pump 182, so that the water is not transferred from the treated water tank 160 to the

disinfecting tank 170. For example, by setting the transfer capacity of the third air lift pump 182,

the difference between the high water level and the low water level is kept at about 10 cm. At this

time, preferably, the transfer capacity of the third air lift pump 182 is set such that the water level

changes from the high water level to the low water level in about one hour. By thus setting the

transfer capacity of the third air lift pump 182, the time required for increase of the amount of the

water to be transferred by the first and second air lift pumps 180, 181 is prevented from

unnecessarily increasing, so that sludge is more easily precipitated in the tanks.

[0045]

Inlet ports of the first and second air lift pumps 180, 181 are arranged at a lower position

than the inlet port 184 of the third air lift pump 182 and close to the bottoms of the anaerobic

FJC1501 AU10

treatment tank 140 and the aerobic treatment tank 150, respectively. Thus, the first and second air

lift pumps 180, 181 always return sludge to the inflow baffle 110 together with water to be treated.

Therefore, while the water level fluctuates between the low water level and the high water level,

water to be treated circulates through the sedimentation separation tank 120, the anaerobic

treatment tank 140, the aerobic treatment tank 150 and the treated water tank 160. In this manner,

water to be treated is efficiently treated in each tank. Therefore, the water treatment apparatus 100

is provided which realizes higher efficiency relating to treatment of water to be treated. Thus, the

capacity of each tank can be reduced. Therefore, the water treatment apparatus 100 can be

prevented from being increased in size. Further, sludge is efficiently returned to the inflow baffle

110 (the sedimentation separation tank 120).

[0046]

The lifting height of each of the first to third air lift pumps 180 to 182 fluctuates as the

water level of the water treatment region fluctuates. Specifically, as the water level of the water

treatment region rises, the lifting height decreases and the amount of water to be treated which is

transferred by the air lift pumps increases. On the other hand, as the water level of the water

treatment region drops, the lifting height increases and the amount of water to be treated which is

transferred by the air lift pumps decreases. Therefore, by using the air lift pumps, when the

amount of wastewater which flows into the water treatment apparatus 100 increases and the water

level of the water treatment region rises, the capacity of the air lift pumps can be improved

according to rise of the water level. For example, preferably, the dimensions of the flow passages

inside the air lift pumps are set such that the amount of water which is transferred by the first and

second air lift pumps 180, 181 at the high water level is increased to about three to six times of that

at the low water level. As a result, sludge is efficiently returned to the inflow baffle 110 by the first

and second air lift pumps 180, 181.

FJC1501 AU10

[0047]

According to the above-described first embodiment, in the water treatment apparatus

100, the cleaning hole 130 is arranged to be surrounded by the sedimentation separation tank 120

in plan view. Therefore, the cleaning hole 130 communicates with the sedimentation separation

tank 120 in plural directions. Specifically, the cleaning hole 130 communicates with the

sedimentation separation tank 120 in the transverse direction and the longitudinal direction of the

treatment tank body 101. Thus, the water to be treated efficiently flows between the

sedimentation separation tank 120 and the cleaning hole 130.

[0048]

Further, according to the first embodiment, a swirl flow of water to be treated is

generated in the cleaning hole 130 by air supplied from the first diffusing pipe 190, and by the

swirl flow of the water, the water efficiently flows between the sedimentation separation tank 120

and the cleaning hole 130.

[0049]

Further, according to the first embodiment, air supplied from the first diffusing pipe 190

is subdivided or fined (into fine bubbles) by passing through the filter 132, so that sludge

contained in the swirl flow of water to be treated in the cleaning hole 130 is effectively aerobically

treated by fine bubbles. Further, sludge containing fine bubbles is supplied into the sedimentation

separation tank 120, so that generation of scum is promoted and the sludge is stored at a high

concentration in the sedimentation separation tank 120.

[0050]

Further, according to the first embodiment, water to be treated which is returned to the

inflow baffle 110 by the first and second air lift pumps 180, 181 improves the denitrification

performance of the anaerobic filter bed 144. Specifically, water to be treated which is returned

FJC1501 AU10

from the aerobic treatment tank 150 to the inflow baffle 110 by the second air lift pump 181

contains a lot of DO (dissolved oxygen), but water to be treated which is returned from the

anaerobic treatment tank 140 to the inflow baffle 110 by the first air lift pump 180 contains little

DO. Therefore, the amount of DO in the water to be treated which is returned to the inflow baffle

110 is prevented from increasing. As a result, by water to be treated which is thereafter transferred

again to the anaerobic treatment tank 140, deterioration of the denitrification performance of the

anaerobic filter bed 144 is prevented.

[0051]

Next, the structure of the water treatment apparatus 100 according to a second

embodiment of the present invention is explained with reference to FIGS. 8 and 9. As shown in

FIGS. 8 and 9, in the second embodiment, the cleaning hole 130 and the first diffusing pipe 190

are not provided in the sedimentation separation tank 120. In the second embodiment, like in the

first embodiment, water to be treated circulates through the sedimentation separation tank 120, the

anaerobic treatment tank 140, the aerobic treatment tank 150 and the treated water tank 160 via the

first and second air lift pumps 180, 190. Thus, sludge is efficiently returned to the sedimentation

separation tank 120. Therefore, when the capacity of the sedimentation separation tank 120 is

large enough to separate sludge from the water to be treated and to precipitate the sludge, the

cleaning hole 130 and the first diffusing pipe 190 may be dispensed with.

[0052]

Further, in the above-described embodiments, the air lift pumps are provided in the

water treatment apparatus 100, but a submerged pump may be provided in place of the air lift

pump. In this case, a controller is provided to control the amount of the water to be treated which

is transferred by the submerged pump, according to fluctuation of the water level.

[0053]

FJC1501 AU10

Further, in the above-described embodiments, the water treatment apparatus 100 is

described as having the inflow baffle 110, the sedimentation separation tank 120, the cleaning hole

130, the anaerobic treatment tank 140, the aerobic treatment tank 150, the treated water tank 160

and the disinfecting tank 170 as treatment elements, but various numbers and kinds of treatment

elements can be selected as necessary.

[0054]

Further, in the above-described embodiments, the water treatment apparatus 100 for

treating raw water discharged from general houses and apartment houses is described, but this

invention can also be applied to water treatment apparatus for treating raw water discharged from

commercial facilities, public facilities, factories and other similar facilities as well as general

houses and apartment houses.

[0055] (Correspondences between the features of the embodiments and the features of the

invention)

The above-described embodiments are representative examples for embodying the

present invention, and the present invention is not limited to the constructions that have been

described as the representative embodiments. Correspondences between the features of the

embodiments and the features of the invention are as follow.

The water treatment apparatus 100 is an example embodiment that corresponds to the

"water treatment apparatus" according to this invention.

The inflow baffle 110 is an example embodiment that corresponds to the "inflow tank"

according to this invention.

The sedimentation separation tank 120 is an example embodiment that corresponds to

the "inflow tank" according to this invention.

The anaerobic treatment tank 140 is an example embodiment that corresponds to the

FJC1501 AU10

"anaerobic treatment tank" according to this invention.

The first anaerobic chamber 141 is an example embodiment that corresponds to the

"first chamber" according to this invention.

The second anaerobic chamber 142 is an example embodiment that corresponds to the

"second chamber" according to this invention.

The aerobic treatment tank 150 is an example embodiment that corresponds to the

"aerobic treatment tank" according to this invention.

The aerobic treatment tank 150 is an example embodiment that corresponds to the"third

chamber" according to this invention.

The treated water tank 160 is an example embodiment that corresponds to the "aerobic

treatment tank" according to this invention.

The treated water tank 160 is an example embodiment that corresponds to the "fourth

chamber" according to this invention.

The opening 106a is an example embodiment that corresponds to the "communication

hole" according to this invention.

The opening 106b is an example embodiment that corresponds to the "communication

hole" according to this invention.

The first air lift pump 180 is an example embodiment that corresponds to the "first

circulation device" according to this invention.

The second air lift pump 181 is an example embodiment that corresponds to the "second

circulation device" according to this invention.

The third air lift pump 182 is an example embodiment that corresponds to the "water

discharging transfer device" according to this invention.

The inlet port 184 is an example embodiment that corresponds to the "intake port"

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according to this embodiment.

Description of the Numerals

[0056]

100 water treatment apparatus

101 treatment tank body

101a side wall

101b side wall

101c side wall

101d side wall

101e bottom wall

101f top wall

102 inlet pipe

103 outlet pipe

104 manhole part

105 partition wall

105a opening

105b opening

106 partition wall

106a opening

106b opening

110 inflow baffle

120 sedimentation separation tank

130 cleaning hole

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130a lower end opening

130b upper end opening

131 division wall

132 filter

140 anaerobic treatment tank

141 first anaerobic chamber

142 second anaerobic chamber

143 division wall

144 anaerobic filter bed

150 aerobic treatment tank

151 aerobic filter bed

160 treated water tank

161 division wall

170 disinfecting tank

171 division wall

180 first air lift pump

181 second air lift pump

182 third air lift pump

183 pump housing

183a first flow passage

183b second flow passage

184 inlet port

185 air supply port

186 discharge port

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187 partition part

190 first diffusing pipe

191 second diffusing pipe

Claims

The claims defining the invention are as follows:

1. A water treatment apparatus for treating water to be treated containing sludge, comprising: an inflow tank into which water to be treated is introduced, an anaerobic treatment tank which is disposed on a downstream side of the inflow tank and anaerobically treats water to be treated, an aerobic treatment tank which is disposed on a downstream side of the anaerobic treatment tank and aerobically treats water to be treated, a water discharging transfer device for transferring treated water in order to discharge the treated water out of the water treatment apparatus, a first circulation device for transferring water to be treated from the anaerobic treatment tank to the inflow tank to circulate the water, a second circulation device for transferring water to be treated from the aerobic treatment tank to the inflow tank to circulate the water, the first circulation device includes a first air lift pump to transfer the sludge deposited close to the bottoms of the anaerobic treatment tank to the inflow tank together with the water to be treated, the second circulation device includes a second air lift pump to transfer the sludge deposited close to the bottoms of the aerobic treatment tank to the inflow tank together with the water to be treated, the aerobic treatment tank is provided as a single chamber, in which aerobic filter media is disposed for aerobic treatment of the water to be treated and the water to be treated is transferred by downward flow, the treated water tank is provided such that the water to be treated is transferred by upward flow in the treated water tank, the aerobic filter media is defined by a fixed filter bed fixed to the water treatment apparatus, wherein levels of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic treatment tank fluctuate at the same level.

2. The water treatment apparatus as defined in claim 1, wherein the aerobic filter media comprise a three-dimensional net-like body.

3. The water treatment apparatus as defined in claim 1 or 2, wherein a position of a lower end of an intake port of the water discharging transfer device in a vertical direction defines a low water level of the water to be treated in the inflow tank, the anaerobic treatment tank and the aerobic treatment tank.

4. The water treatment apparatus as defined in claim 3, wherein a lower end of a communication hole for communication between the anaerobic treatment tank and the aerobic treatment tank is arranged at a lower position than the lower end of the intake port of the water discharging transfer device, and an upper end of the communication hole is arranged at a higher position than the lower end of the intake port of the water discharging transfer device, so that the low water level is set in a middle region of the communication hole.