JP6043111B2 - Wastewater treatment equipment - Google Patents

Description

  The present invention relates to wastewater treatment using microorganisms.

  Conventionally, wastewater treatment has been performed using microorganisms. For example, a wastewater treatment apparatus including a contact aeration tank using aerobic microorganisms is used. As a technique using a contact aeration tank, for example, a contact material for fixing aerobic microorganisms in a contact aeration tank and air from a blower are supplied into the tank and water to be treated is supplied into the contact aeration tank. A technique for providing an air diffuser that generates a circulating flow has been proposed.

Japanese Patent Laid-Open No. 5-111692

  When performing biological treatment using aerobic microorganisms, a blower with a sufficient air volume is used to supply sufficient oxygen to every corner of the contact material. By the way, in recent years, the importance of energy saving is increasing. However, the actual situation is that sufficient ideas have not been made to save energy. Such a problem is not limited to wastewater treatment using a contact material, but is common to wastewater treatment using aerobic microorganisms.

  The main advantage of the present invention is to provide a technology that can save energy while realizing biological treatment.

The present invention has been made to solve at least a part of the above-described problems.
It can be realized as an aspect or an application example.
[Aspect]
Wastewater treatment equipment,
A biological treatment tank for biologically treating the water to be treated;
A support member disposed in the biological treatment tank for supporting microorganisms;
An air diffuser disposed below the support member of the biological treatment tank and supplying bubbles containing oxygen to the support member;
A gas supply unit that alternately repeats the supply of gas containing oxygen to the aeration unit and the stop of the supply;
A pre-treatment unit for receiving inflow water to the wastewater treatment device and supplying the accepted water to the biological treatment tank;
With
The pre-treatment unit is configured such that the supply amount of the water per unit time to the biological treatment tank varies according to the variation of the inflow amount per unit time of the inflow water,
The gas supply unit is an air volume that is an amount of gas per unit time, and an air volume that can obtain an oxygen amount necessary to achieve a target water quality by repeating the supply of the gas and the stop of the supply. And supplying the gas with an air volume larger than that required to obtain the required oxygen amount when the gas supply is continuously performed without stopping the gas supply.
Wastewater treatment equipment.

Application Example 1 A biological treatment tank for biologically treating water to be treated, a supporting member for supporting microorganisms disposed in the biological processing tank, and disposed below the supporting member of the biological treatment tank. A wastewater treatment apparatus comprising: an air diffuser that supplies bubbles containing oxygen to the support member; and a gas supply unit that alternately repeats the supply of the gas containing oxygen to the air diffuser and the stop of the supply .
According to this configuration, when the gas supply unit supplies gas to the aeration unit, it is possible to realize biological treatment of water to be treated by microorganisms supported on the support member. Furthermore, energy can be saved compared with the case where the gas supply unit continues the gas supply without stopping the gas supply by alternately repeating the gas supply and the supply stop.

[Application Example 2] The waste water treatment apparatus according to Application Example 1, wherein the supporting member is fixed in the biological treatment tank, and the diffuser is viewed from above downward. A wastewater treatment apparatus having a plurality of diffused holes arranged in a range of the bottom of the region where the support member is arranged.
According to this configuration, since the gas supply unit supplies gas to the aeration unit, it is possible to supply bubbles to almost the entire area of the bottom of the support member. Can be reduced. Therefore, the biological treatment of the water to be treated can be appropriately realized. Furthermore, energy can be saved by the gas supply unit alternately repeating the supply of gas and the stop of supply.

[Application Example 3] The waste water treatment apparatus according to Application Example 2, wherein the gas supply unit is connected to the gas diffusion unit when the gas diffusion unit and the support member are viewed from above downward. A wastewater treatment apparatus configured to supply the gas so that the bubbles rise from substantially the entire upper area of the region where the support member is disposed.
According to this configuration, it is possible to reduce the possibility that a portion in which bubbles are not supplied to the support member is generated, and thus biological treatment of water to be treated can be appropriately realized.

[Application Example 4] The wastewater treatment apparatus according to any one of Application Examples 1 to 3, further receiving inflow water to the wastewater treatment apparatus and supplying the received water to the biological treatment tank The pretreatment unit is configured to change a supply amount of the water per unit time to the biological treatment tank according to a change in an inflow amount of the inflow water per unit time. The waste water treatment equipment is configured to.
According to this configuration, as a configuration of the upstream processing unit, a small configuration that does not have a large water treatment tank (for example, a flow rate adjustment tank capable of storing one day's worth of inflow water) that can completely absorb inflow fluctuations. Can be adopted. And in the waste water treatment apparatus which has such a small front | former process part, energy can be saved, implement | achieving biological treatment.

[Application Example 5] The waste water treatment apparatus according to any one of Application Examples 1 to 4, wherein the gas supply unit alternately repeats the supply of the gas and the stop of the supply at a cycle shorter than half a day. Wastewater treatment equipment.
According to this configuration, it is possible to prevent the gas supply stoppage from continuing for a long time, so that it is possible to reduce the possibility of problems such as oxygen shortage occurring in biological treatment.

[Application Example 6] The waste water treatment apparatus according to any one of Application Examples 1 to 5, further including an upstream treatment tank disposed upstream of the biological treatment tank, and the gas from the gas supply unit. A pair of metals immersed in the biological treatment tank or an air lift pump that transfers water from the downstream side of the biological treatment tank to the upstream treatment tank, and transfer water that is transferred by the air lift pump An electrode and an energization unit that elutes the metal ions of the metal electrode into the transfer water by energizing the pair of metal electrodes in order to react with the phosphorus component in the transfer water, , During at least a part of the time when the gas supply unit supplies the gas, the energization is performed, and at least a part of the time when the gas supply unit stops supplying the gas, To stop the serial energization, waste water treatment equipment.
According to this structure, since electricity supply is performed when the gas supply part is supplying gas, a metal ion can be eluted to the water transferred by an air lift pump. Further, when the gas supply unit stops supplying gas, that is, when the air lift pump is not transferring water, the energization is stopped, so that energy can be saved.

  In addition, this invention can be implement | achieved with various forms, for example, implement | achieves with forms, such as a biological treatment tank, the waste water treatment equipment provided with a biological treatment tank, the waste water treatment method using a biological treatment tank, etc. Can do.

It is explanatory drawing which shows the processing flow of the waste water treatment equipment. The schematic structure which looked at the waste water treatment equipment 800 from the side is shown. The schematic structure of the waste water treatment apparatus 800 is shown. The schematic structure of the waste water treatment apparatus 800 is shown. It is a perspective view which shows the contact filter bed tank 830, the treated water tank 840, and the disinfection tank 850. It is the schematic which shows the structure of the diffuser 834 and the mount frame 839. It is the schematic which shows the mode of aeration in the contact filter bed tank 830. FIG. It is a graph which shows the measurement result of the quality of treated water. It is a graph which shows the measurement result of the quality of treated water. It is a graph which shows the measurement result of the quality of treated water. It is a graph which shows the measurement result of the quality of treated water. It is a schematic block diagram of the waste water treatment equipment 800x. It is the schematic which shows the structure of another Example of a waste water treatment apparatus. It is the schematic which shows another example of a waste water treatment tank.

[A. First Example]
[A-1. Device configuration]
Next, embodiments of the present invention will be described based on examples. FIG. 1 is an explanatory diagram showing a processing flow of a wastewater treatment apparatus 800 as an embodiment of the present invention. The waste water treatment apparatus 800 of this embodiment performs a purification process of waste water from a general household (such an apparatus is also called a “septic tank”). In order to carry out purification treatment through a plurality of steps, the waste water treatment apparatus 800 is arranged in order from the upstream side (left side in FIG. 1), a contaminant removal tank 810, an anaerobic filter bed tank 820, a contact filter bed tank 830, a treated water tank. 840 and a disinfection tank 850 are accommodated. The wastewater that has flowed into the wastewater treatment apparatus 800 is sequentially treated in the contaminant removal tank 810, the anaerobic filter bed tank 820, the contact filter bed tank 830, the treated water tank 840, and the disinfection tank 850, and then discharged to the outside of the wastewater treatment apparatus 800. Is done. Hereinafter, water flowing through each water treatment tank is referred to as “water to be treated” or simply “water”. Further, a blower 500 is connected to the waste water treatment apparatus 800. The wastewater treatment apparatus 800 uses the gas (here, air) containing oxygen supplied by the blower 500 to proceed with the purification treatment.

  FIG. 2 shows a schematic configuration of the waste water treatment apparatus 800 viewed from the side. FIG. 3 shows a schematic configuration of the waste water treatment apparatus 800 viewed downward from the AA cross section in FIG. FIG. 4 shows a schematic configuration of the waste water treatment apparatus 800 viewed from the BB cross section in FIG. 2 toward the contaminant removal tank 810 side. FIG. 5 is a perspective view showing a contact filter bed tank 830, a treated water tank 840, and a disinfection tank 850. In these drawings, the Z direction indicates the direction from the lower side to the upper side in the vertical direction, the X direction indicates the longitudinal direction (horizontal direction) of the waste water treatment apparatus 800, and the Y direction indicates the X direction and the Z direction. The direction (horizontal direction) orthogonal to each of the is shown. Hereinafter, the X direction side is also referred to as “+ X side”, and the opposite direction side of the X direction is also referred to as “−X side”. The same applies to the Y direction and the Z direction.

  The contaminant removal tank 810 (FIG. 1) is a water treatment tank that separates contaminants in the waste water. As shown in FIGS. 2 and 3, the contaminant removal tank 810 is disposed at the most upstream part of the tank body 801 that forms the outer wall of the waste water treatment apparatus 800. Waste water (also called sewage) from the inflow port 802 first flows into the contaminant removal tank 810. The contaminant removal tank 810 has solid-liquid separation means such as an inflow baffle 812 and separates contaminants in the waste water from the water to be treated. The water after the impurities are separated (removed) is transferred to the anaerobic filter bed tank 820 through the transfer opening 814.

  The anaerobic filter bed tank 820 (FIG. 1) is a water treatment tank that performs anaerobic treatment with anaerobic microorganisms. As shown in FIGS. 2 and 3, the anaerobic filter bed tank 820 has a filter medium 822 for attaching anaerobic microorganisms. The organic matter in the for-treatment water is decomposed by the anaerobic treatment. Further, as will be described later, in the anaerobic filter bed tank 820, water aerobically treated in the contact filter bed tank 830 (water containing nitrate ions (also referred to as nitrification solution)) is removed from the circulating air lift pump 860 and impurities. It flows in through the tank 810. In the anaerobic filter bed tank 820, nitrogen gas is generated from nitrate ions by the action of denitrifying bacteria contained in the anaerobic microorganisms and released into the air (so-called denitrification). Moreover, the filter medium 822 can capture floating substances in the water to be treated.

  As shown in FIGS. 2 and 3, the side wall 803 on the downstream side (+ X side) of the anaerobic filter bed tank 820 divides the tank body 801 into two perpendicular to the X direction (hereinafter referred to as side walls). 803 is also referred to as “partition plate 803”). As shown in FIG. 3, on the downstream side (+ X side) of the partition plate 803, side wall portions 843, 842, and 844 arranged in a substantially U shape as viewed from above are fixed. A space surrounded by the partition plate 803 and the side wall portions 843, 842, 844 corresponds to the treated water tank 840. The lower portion 849 of the treated water tank 840 has a so-called hopper structure (hereinafter, the lower portion 849 is also referred to as “hopper portion 849”). A space around the treated water tank 840 (a space in the three directions of + Y side, + X side, and −Y side of the treated water tank 840) corresponds to the contact filter bed tank 830.

  The second side wall portion 842 (FIG. 3) is disposed so as to face the partition plate 803. The third side wall portion 843 connects the end portion on the + Y side of the second side wall portion 842 and a portion on the −Y side with respect to the end on the + Y side of the partition plate 803. The fourth side wall portion 844 connects the end portion on the −Y side of the second side wall portion 842 and a portion on the + Y side of the end portion on the −Y side of the partition plate 803. Hereinafter, a portion of the partition plate 803 between the third side wall portion 843 and the fourth side wall portion 844 (a portion functioning as a side wall of the treated water tank 840) is also referred to as a “first side wall portion 841”.

  An advection opening 824 is formed in a part of the partition plate 803 (FIGS. 2 and 3) that forms a boundary between the anaerobic filter bed tank 820 and the contact filter bed tank 830. The advection opening 824 is disposed in the upper part of the partition plate 803, and the water surface WL (a low water level LWL described later) is normally located in the middle of the advection opening 824. The water treated in the anaerobic filter bed tank 820 is transferred to the contact filter bed tank 830 through the transfer opening 824.

  The contact filter bed tank 830 (FIG. 1) is a water treatment tank that performs aerobic treatment with aerobic microorganisms. As shown in FIGS. 2, 4, and 5, a grid-like gantry 839 is provided in the lower part of the contact filter bed tank 830 (above the advection opening 836). An air diffuser 834 is placed on the gantry 839. Further, a contact material 832 and an aerobic filter material 833 for supporting microorganisms are disposed on the gantry 839 (aeration device 834). Hereinafter, the entirety of the contact material 832 and the aerobic filter material 833 is referred to as a supporting member 835. The aerobic filter medium 833 is disposed on the gantry 839, and the contact material 832 is disposed on the aerobic filter medium 833. The air diffuser 834, the contact material 832, and the aerobic filter material 833 are disposed on both sides (+ Y side and −Y side) of the treated water tank 840 (FIGS. 3 to 5). The aerobic filter medium 833 is also arranged on the + X side of the treated water tank 840 (FIG. 5). Hereinafter, when distinguishing two identical members arranged on the + Y side and the −Y side, a letter “p” is added to the end of the sign of the + Y side member, and at the end of the sign of the −Y side member. The letter “m” is added. The aerobic filter medium 833 disposed below the + Y side contact material 832p is also referred to as an aerobic filter medium 833p. The aerobic filter medium 833 arranged below the −Y side contact material 832m is also referred to as an aerobic filter medium 833m.

  A gas including oxygen (here, air) is supplied from the blower 500 to the air diffuser 834 (FIG. 4). The connection between the air diffuser 834 and the blower 500 will be described later. The air diffuser 834 is configured using a pipe having a plurality of holes (not shown) provided on the bottom surface. The arrows in FIG. 5 indicate the flow of water, and a number of small circles BB indicate the bubbles supplied by the air diffuser 834. As illustrated, the air diffuser 834 supplies bubbles BB containing oxygen to the support member 835. A large number of bubbles BB discharged from the air diffuser 834 pass through the inside of the support member 835 (members 832 and 833) and reach the water surface WL. The aerobic microorganisms carried on the carrying member 835 (members 832 and 833) decomposes organic substances in the water to be treated using oxygen contained in the bubbles BB. In addition, by the action of nitrifying bacteria contained in the aerobic microorganism, ammonium ions contained in the water to be treated are oxidized to produce nitrite ions and nitrate ions (nitrification). Water (nitrification liquid) containing nitrate ions is transferred to the contaminant removal tank 810 by a circulating air lift pump 860 described later.

  FIG. 5 shows a schematic configuration of the contact material 832 and the aerobic filter material 833. The contact material 832 is formed by arranging a plurality of resin-made plates having a number of wavy irregularities arranged at predetermined intervals. The contact material 832 is fixed in the contact filter bed tank 830 (specifically, on the partition plate 803 and the side walls 843 and 844) by a fixing tool (not shown).

  The aerobic filter material 833 is a resin-like net-like skeleton formed into a cylindrical shape. A large number of cylindrical members (aerobic filter media 833) are filled in the space between the gantry 839 and the contact material 832. Further, the aerobic filter medium 833 is also filled in a space between the hopper portion 849 (FIG. 2) of the treated water tank 840 and the tank body 801. In a state where the waste water treatment apparatus 800 is completed, a large number of aerobic filter media 833 are surrounded by the tank body 801, the gantry 839, the contact material 832, and the treated water tank 840 (side walls 843, 842, 844). The aerobic filter medium 833 cannot move freely, and is substantially stationary in the contact filter bed tank 830. Thus, since it is substantially stationary in the contact filter bed tank 830, it can be said that the aerobic filter medium 833 is fixed in the contact filter bed tank 830.

  The air diffuser 834 is disposed below the aerobic filter medium 833. Bubbles BB discharged from the air diffuser 834 come into contact with the aerobic filter medium 833. As described above, the aerobic filter medium 833 has a net-like structure. Therefore, the bubbles BB are subdivided by the net-like aerobic filter medium 833. As a result, the oxygen dissolution efficiency can be improved. Thus, it is preferable that the support member includes a mesh member (for example, an aerobic filter medium 833) having a mesh structure, and the air diffuser 834 is disposed below the mesh member.

  As shown in FIGS. 2 and 4, the water treated in the contact filter bed tank 830 is transferred to the treated water tank 840 through a transfer opening 836 that communicates the bottom of the contact filter bed tank 830 and the bottom of the treatment water tank 840. .

  The treated water tank 840 (FIG. 1) is a water treatment tank that temporarily retains the water transferred from the contact filter bed tank 830 and settles and separates solids (for example, sludge and suspended solids) in the water. As shown in FIG. 2, the treated water tank 840 has a hopper portion 849. In the hopper portion 849, the second side wall portion 842 is inclined with respect to the vertical direction, and the cross-sectional area (horizontal cross-sectional area) of the treated water tank 840 is smaller as it is closer to the bottom wall 845 of the treated water tank 840. Further, as shown in FIG. 4, in the lower portion 849L of the hopper portion 849, each of the third side wall portion 843 and the fourth side wall portion 844 is also inclined with respect to the vertical direction. The lower portion 849L has a so-called three-surface hopper structure. The separated solid matter in the treated water tank 840 is collected at the bottom of the treated water tank 840 (space narrower than the upper part of the treated water tank 840) by the side wall portions 842, 843, and 844.

  As shown in FIG. 2, the lower end of the partition plate 803 (first side wall portion 841) is connected to the bottom surface of the tank body 801. On the other hand, as shown in FIGS. 2 and 4, the lower ends of the other side wall portions 842, 843, and 844 are separated from the bottom surface of the tank body 801. The gaps between the lower ends of the side wall portions 842, 843, and 844 and the bottom surface of the tank body 801 correspond to the advection opening 836.

  As shown in FIG. 2, a circulating air lift pump 860 is provided in the treated water tank 840. The circulating air lift pump 860 has a vertical pipe 861 extending upward from the bottom of the treated water tank 840 to above the water surface WL (a high water level HWL described later). An advection pipe 863 that extends with a gentle downward slope is connected to the upper part of the vertical pipe 861 (the part above the high water level HWL) to above the water surface WL of the contaminant removal tank 810. An end on the bottom side of the vertical tube 861 forms a suction port 862. An end of the advection pipe 863 on the side of the contaminant removal tank 810 forms a discharge port 864. The circulating air lift pump 860 transfers (returns) solid matter and water (nitrating liquid) from the bottom of the treated water tank 840 to the contaminant removal tank 810. As described above, since the lower portion 849 of the treated water tank 840 has a hopper structure, the solid matter separated in the treated water tank 840 is collected in a narrow space at the bottom (near the inlet 862). As a result, the separated solid matter can be easily removed from the treated water tank 840. The circulating air lift pump 860 operates using the gas supplied by the blower 500 (FIG. 4). The connection between the circulating air lift pump 860 and the blower 500 will be described later.

  The disinfection tank 850 (FIG. 1) is a water treatment tank that disinfects the water to be treated. The disinfection tank 850 is disposed on the upper part of the treated water tank 840 (FIG. 2). In this embodiment, the disinfection tank 850 has a discharge air lift pump 870. The suction port 872 of the discharge air lift pump 870 is disposed at a predetermined height (referred to as a low water level LWL) in the treated water tank 840, and the discharge port 874 of the discharge air lift pump 870 is disposed upstream of the disinfection tank 850. ing. Water in the vicinity of the water surface WL of the treated water tank 840 (water from which solid matter has been separated) flows into the discharge air lift pump 870 from the suction port 872. The water level WL can drop to the low water level LWL. The water flowing into the discharge air lift pump 870 is transferred little by little to the disinfection tank 850 by the discharge air lift pump 870. The discharge air lift pump 870 operates using the gas supplied by the blower 500 (FIG. 4). The disinfecting tank 850 has a medicine cylinder 854 filled with a disinfectant (for example, a solid chlorine agent). In the disinfection tank 850, the water to be treated comes into contact with the disinfectant, and the water to be treated is disinfected by the disinfectant. The sterilized water is discharged to the outside of the waste water treatment apparatus 800 through the outlet 804.

  When a large amount of wastewater temporarily flows into the wastewater treatment device 800 (for example, at the peak inflow), the water levels WL of the water treatment tanks 810, 820, 830, and 840 upstream of the discharge air lift pump 870 are temporarily Therefore, it can rise above the normal water level (low water level LWL in the figure). In the embodiment of FIG. 2, the water level WL can rise to the high water level HWL (the water level below the high water level HWL does not overflow). Thus, at the peak inflow, the increase in the amount of outflow per unit time from the contact filter bed tank 830 is suppressed by temporarily increasing the water levels of the plurality of water treatment tanks 810, 820, 830, and 840. . As a result, the possibility of untreated water flowing out from the contact filter bed tank 830 can be reduced. In this way, the discharge air lift pump 870 operates as a mechanism that suppresses an increase in the amount of outflow per unit time from the contact filter bed tank 830 caused by peak inflow (referred to as a “peak cut mechanism”).

  Next, the flow path of the gas from the blower 500 will be described. As shown in FIG. 4, an air supply port 610 is provided at the top of the tank body 801. Outside the waste water treatment apparatus 800, the blower 500 is connected to the air supply port 610 via the connection pipe 502. The blower 500 includes a drive unit 510 and a control unit 520. The drive unit 510 includes a solenoid, a vibrator, a diaphragm, and a compression chamber (not shown), and is a device that pumps air. The drive unit 510 is not limited to a diaphragm type device, and a device such as a rotary type that pumps various air can be employed. The control unit 520 is a device that controls the drive unit 510. Control unit 520 includes a timer, receives power supply from a household power supply, and intermittently operates drive unit 510 (details will be described later).

  Inside the waste water treatment apparatus 800, an air diffuser valve 620, a circulation valve 630, and a discharge valve 640 are connected to the air supply port 610.

  Two air supply pipes 622 are connected to the air diffusion valve 620. The + Y side air supply pipe 622p is connected to the + Y side air diffuser 834p, and the -Y side air supply pipe 622m is connected to the -Y side air diffuser 834m. The air diffuser valve 620 distributes the gas supplied from the blower 500 to the + Y side air diffuser 834p and the −Y side air diffuser 834m. The user can adjust the distribution amount (balance) by adjusting the air diffusion valve 620.

  A circulation air lift pump 860 is connected to the circulation valve 630 via an air supply pipe 632. The user can adjust the transfer amount (circulation water amount) per unit time by the circulation air lift pump 860 by adjusting the circulation valve 630.

  A discharge air lift pump 870 (FIGS. 2 and 3) is connected to the discharge valve 640 via an air supply pipe (not shown). The user can adjust the transfer amount (discharge flow rate) per unit time by the discharge air lift pump 870 by adjusting the discharge valve 640.

  FIG. 6 is a schematic diagram showing the configuration of the air diffuser 834 and the gantry 839. In the drawing, an air diffuser 834, a gantry 839, a tank body 801, a partition plate 803, side walls 842, 843, and 844, and a contact member 832 are shown as viewed from above to below. The illustrated side wall portions 842, 843, and 844 are portions viewed downward from a cross section at the same height as the gantry 839 (a height in the middle of the hopper portion 849 (FIGS. 2 and 4)). . The gaps between the side wall portions 842, 843, 844 and the gantry 839 are sufficiently smaller than the size of the aerobic filter medium 833 (FIG. 5). The tank body 801 and the partition plate 803 shown in the figure are portions viewed downward from a cross section at a position above the gantry 839. As shown in FIGS. 2 and 4, in the lower half of the tank body 801, the size (outer shape) of the tank body 801 is smaller as it is closer to the bottom. At the same height as the gantry 839, the outer shape of the tank body 801 is smaller than the outer shape shown in FIG. 6, and the gap between the tank body 801 and the gantry 839 is sufficiently smaller than the size of the aerobic filter medium 833. Similarly, the gap between the partition plate 803 and the gantry 839 is also sufficiently smaller than the size of the aerobic filter medium 833.

  The aerobic filter medium 833 (FIG. 5) is disposed on the gantry 839. Therefore, the range inside the outline of the gantry 839 (the hatched range) is the same as the range at the bottom of the region where the aerobic filter medium 833 is disposed.

  The air diffuser 834 has a loop portion 834a and a straight portion 834b. The loop portion 834a is disposed in a space adjacent to the Y direction when viewed from the treated water tank 840. When viewed from above, the loop portion 834 a overlaps the contact material 832. The straight line portion 834b is disposed on the + X side of the treated water tank 840, and extends from the loop part 834a toward the treated water tank 840 side in parallel with the Y direction. The straight portion 834b is disposed in a space between the hopper portion 849 (FIG. 2) and the tank body 801.

  Black circles 834h in FIG. 6 indicate air diffusion holes. Actually, the air holes 834h are formed at the bottom of the air diffuser 834. FIG. 6 shows an air hole 834h seen through the air diffuser 834. As shown in the drawing, eleven air holes 834h are arranged approximately evenly in the loop portion 834a. Two aeration holes 834h are arranged in the straight portion 834b. When viewed from the upper side to the lower side, the plurality of air diffusion holes 834h are in the range of the bottom of the region where the aerobic filter medium 833 is arranged (the range inside the outline of the gantry 839 (the range with hatching)). It is distributed. Therefore, since the air diffuser 834 can supply bubbles to almost the entire bottom of the region where the aerobic filter medium 833 is arranged (that is, the bottom of the support member 835), the aerobic filter medium 833, and hence the contact material. The possibility that a portion where air bubbles are not supplied to 832 can be reduced. Further, the gantry 839 covers the entire bottom of the contact filter bed tank 830. That is, the air diffuser 834 supplies bubbles over substantially the entire bottom surface of the contact filter bed tank 830.

[A-2. Experimental result]
Next, the experiment using the test tank and the result will be described. In this experiment, an attempt was made to save energy while realizing biological treatment by operating the contact filter bed tank 830 with intermittent aeration. Specifically, raw water adjusted assuming drainage from households was allowed to flow into a test tank, and the quality of treated water from the test tank was measured. In addition, the state of aeration (aeration) in the contact filter bed tank 830 was also observed. FIG. 7 is a schematic view showing the state of aeration in the contact filter bed tank 830. 8-11 is a graph which shows the measurement result of the quality of treated water. The horizontal axis indicates the number of days elapsed from the experiment start date, and the vertical axis indicates the concentration (mg / L). When the concentration is below the lower limit of measurement, the concentration is plotted as zero. 8 shows biochemical oxygen demand (BOD), FIG. 9 shows suspended matter (SS), FIG. 10 shows total nitrogen (TN), and FIG. 11 shows nitrite nitrogen. _(NO 2 -N), nitrate nitrogen _(NO 3 -N), shows the ammonium nitrogen _(NH 4 -N). In this experiment, water was collected approximately every week to measure the water quality.

The test tank realizes the waste water treatment apparatus 800 described above on the assumption that the number of personnel to be treated = 5. For example, the capacity of the contaminant removal tank 810 is 1.048 m ³ , the capacity of the anaerobic filter bed tank 820 is 1.052 m ³ , and the capacity of the contact filter bed tank 830 is 0.482 m ³ , The capacity of the treatment water tank 840 is 0.237 m ³ , and the capacity of the disinfection tank 850 is 0.015 m ³ . The filling rate of the filter medium 822 in the anaerobic filter bed tank 820 is approximately 46%. The filling rate of the contact material 832 is approximately 16%. The filling rate of the aerobic filter medium 833 is approximately 57%. The high water level HWL is 50 mm higher than the low water level LWL. The outer shape of one contact material 832 (FIG. 5) is approximately a rectangular parallelepiped of 330 mm × 500 mm × 250 mm. The outer shape of one aerobic filter medium 833 is a cylindrical shape having a diameter of 100 mm and a height of 100 mm. The thickness of the side wall portion of the cylinder is 15 mm. The diameter of the air holes 834h (FIG. 6) is 3 mm.

Raw water is adjusted assuming drainage from ordinary households. The quality of the adjusted raw water was as follows. Within the experimental period, the average BOD was 200 mg / L, the average TN was 45 mg / L, and the average SS was 160 mg / L. Moreover, the inflow water amount is adjusted to be about 1 m ³ / day. The daily inflow pattern is set by combining normal inflow (13 L / min) and peak inflow (59 L / min) as follows.
Time: Inflow per unit time: Inflow time: Inflow 1:00: 13L / min: 7.7 minutes: 100L
2:00: 13L / min: 11.5 minutes: 150L
3 o'clock: 13 L / min: 6.9 minutes: 90 L
13:00: 13L / min: 2.3 minutes: 30L
14:00: 13L / min: 6.9 minutes: 90L
15:00: 59L / min: 4.2 minutes: 250L
16:00: 13L / min: 7.7 minutes: 100L
17:00: 13L / min: 2.3 minutes: 30L
18:00: 13L / min: 2.3 minutes: 30L
19:00: 13L / min: 3.8 minutes: 50L
23:00: 13L / min: 2.3 minutes: 30L
24:00: 13L / min: 3.8 minutes: 50L
“Time” indicates the time when normal inflow or peak inflow is performed. “Inflow per unit time” indicates the inflow per unit time of waste water. “Inflow time” indicates the time during which the inflow is continued. “Inflow” indicates the inflow of wastewater. For example, at 1 o'clock, normal inflow (13 L / min) is continued for 7.7 minutes, and a total of 100 L of waste water flows into the waste water treatment apparatus 800. Drainage does not flow in at times not listed.

The blower 500 was controlled as follows.
1st period P1 (0th day to 138th day): 70 L / min, continuous operation 2nd period P2 (from 138th day to 207th day): 70 L / min, 60 minutes-ON, 10 minutes-OFF
Third period P3 (from 207th day to 273th day): 60L / min, 60 minutes-ON, 10 minutes-OFF
Fourth period P4 (from the 273rd day to the 328th day): 60 L / min, 50 minutes-ON, 20 minutes-OFF
5th period P5 (from the 328th day): 60 L / min, 40 minutes-ON, 30 minutes-OFF
Here, the number of days is the number of days that have elapsed since the start of the experiment. The “ON” time means a time for continuously driving the blower 500 (drive unit 510) (referred to as “continuous aeration time”), and the “OFF” time means the blower 500 (drive unit 510). ) Is continuously stopped (referred to as “continuous stop time”). For example, “60 minutes-ON, 10 minutes-OFF” indicates that 60-minute continuous driving (aeration) and 10-minute continuous stop (aeration stop) are repeated alternately.

  The air volume of 70 L / min is an air volume that can supply the same amount of oxygen as in the case of continuous operation at an air volume of 60 L / min when intermittent operation (for example, 60 minutes-ON, 10 minutes-OFF) is performed. Hereinafter, the air volume will be described, and then the experimental results will be described.

The theoretical required air volume is calculated as follows. First, the amount of oxygen necessary to achieve the target water quality is calculated. For example, when the amount of influent water corresponding to 5 persons to be treated is 1 m ³ / day and the quality of the influent water is BOD = 200 mg / L, TN = 45 mg / L, BOD ≦ 10 mg / L , The amount of oxygen necessary to achieve the target water quality of TN ≦ 10 mg / L is calculated according to the following equation.
Necessary oxygen (kg-O ₂ / d) = a × Lr + b × Sa + c × N
Each parameter a, Lr, b, Sa, c, N is as follows.
a: Required oxygen amount per unit BOD removal (kg-O ₂ / kg-BOD)
Lr: BOD removal amount-denitrification amount x 3.0 (kg-BOD / d)
b: Necessary oxygen amount by endogenous breath per unit MLSS (kg-O ₂ / kg-MLSS)
Sa: MLSS amount (kg-MLSS)
c: Required oxygen amount per unit nitrification (kg-O ₂ / kg-N)
N: Amount of nitrification (kg-N / d)

Next, an overall oxygen transfer capacity coefficient (referred to as “necessary K _L a”) necessary to obtain the required oxygen amount is calculated. The necessary K _L a is calculated according to the following equation, for example.
Necessary K _L a (h ⁻¹ ) = Rr / {(CS-CL) × 10 ⁻³ } / 24
Each parameter Rr, CS, CL is as follows.
Rr: Necessary oxygen amount per volume of contact filter bed tank (kg-O ₂ / m ³・ d)
CS: Saturated dissolved oxygen concentration at 20 ℃ (g / m ³ )
CL: dissolved oxygen concentration (g / m ³ )

Next, the relationship between the overall oxygen transfer capacity coefficient and the aeration intensity is experimentally determined. Here, various aeration strengths (m ³ / m ³ · h) in the range of 3.5 to 8.7 are used at two locations on the + Y side and the −Y side of the treated water tank 840 using a test tank. The overall oxygen transfer capacity coefficient of the contact filter bed tank 830 was measured. There was almost no difference between the + Y side and the -Y side. The aeration intensity for realizing the necessary K _L a calculated using the regression line of the measurement result was “3.6 m ³ / m ³ · h”.

The capacitance of the contact filter bed tank 830 of the test chamber is "0.482M ^3", the air volume to achieve the above aeration intensity ^{(3.6m 3 / m 3 · h} ) is the "29L / min" . However, with this theoretical required air volume (aeration intensity = 3.6 m ³ / m ³ · h), there is a possibility that the aeration of the contact filter bed tank 830 may be biased, that is, in a part of the support member 835. There may be a lack of oxygen. Therefore, in order to stably perform aeration over the entire surface of the contact filter bed tank 830, an air volume that realizes an aeration intensity having a sufficient margin (5.5 m ³ / m ³ · h) is designated as a design air volume. Adopted. In reality, a part of the gas supplied by the blower 500 is used by the air lift pumps 870 and 860. The air volume of “60 L / min” can realize the aeration intensity (5.5 m ³ / m ³ · h) after subtracting the amount supplied to the air lift pumps 870 and 860. As described above, even when the aeration intensity (air volume) is increased from the theoretical aeration intensity (air volume), the intermittent filtration operation is employed to cover the entire surface of the contact filter bed tank 830. Energy can be saved while realizing stable aeration.

  The circulation amount per unit time by the circulation air lift pump 860 is such that the total circulation water amount for one day when the circulation amount continues for one day is within a range of 4 to 6 times the daily average sewage amount. It has been adjusted to be. Further, the transfer amount by the discharge air lift pump 870 is adjusted so that the water level that has risen to the high water level HWL falls to the low water level LWL within approximately one hour.

  Next, experimental results will be described. The hatched area BA in FIG. 7 indicates an area where rising bubbles are observed when viewed from above to below. FIG. 7 shows a case where the air volume of the blower 500 is 60 L / min. As shown in the figure, it was observed that bubbles rose from almost the entire upper portion of the region where the contact material 832 was disposed (that is, the upper portion of the supporting member 835). Therefore, the possibility that a portion where air bubbles are not supplied to the contact material 832 and thus the aerobic filter material 833 is reduced.

  In addition, the contact material 832 is arrange | positioned over the substantially whole region of the upper part of the contact filter bed tank 830. FIG. Therefore, rising bubbles are observed over almost the entire upper part of the contact filter bed tank 830. In addition, as described with reference to FIG. 6, the air diffuser 834 generates bubbles over almost the entire bottom of the region where the aerobic filter medium 833 is disposed (that is, almost the entire bottom of the contact filter bed 830). Can be supplied. As a result of the above, it is presumed that the air diffuser 834 supplies rising bubbles over the entire support member 835. Such a diffuser system is also called “full aeration”.

Next, the water quality shown in FIGS. 8 to 11 will be described. As shown in the drawing, in the periods P2 to P5 after the start of intermittent aeration, the water quality equivalent to the first period P1 in which the continuous aeration operation is performed is stably realized. Specifically, BOD of 5 mg / L or less was maintained, SS of 5 mg / L or less was maintained, and TN of approximately 10 mg / L was maintained. Further, NH ₄ —N and NO ₂ —N were maintained at approximately zero, and complete nitrification was realized.

  Further, in the periods P3 to P5 in which the intermittent aeration operation is performed, the ratio of the continuous aeration time is “60 minutes / 70 minutes (0.86)”, “50 minutes / 70” while maintaining the air volume at 60 L / min. Minutes (0.71) ”and“ 40 minutes / 70 minutes (0.57) ”. Thus, it was confirmed that good water quality can be maintained even when the ratio of the continuous aeration time is reduced. Moreover, the power consumption of the blower 500 can be reduced as the ratio of the continuous aeration time is smaller. Further, even when the ratio of the continuous aeration time is reduced, the air volume is maintained at 60 L / min. Therefore, as described with reference to FIG. 7, there may be a portion where bubbles are not supplied to the support member 835. Can be reduced.

As described above, the continuous operation with the air volume of 60 L / min corresponds to the aeration intensity of 5.5 m ³ / m ³ · h. Here, the ratio of the continuous operation time at which the average aeration intensity becomes the necessary minimum aeration intensity (3.6 m ³ / m ³ · h) is 3.6 / 5.5 = 0.65. It is. When intermittent aeration operation is performed with a period of 70 minutes, the continuous operation time is 70 minutes × 0.65 = 46 minutes. In the third period P3 and the fourth period P4, the continuous operation time is set to a value (60 minutes, 50 minutes) exceeding the necessary minimum continuous operation time (46 minutes). Therefore, even in the case of intermittent aeration operation, a sufficient amount of oxygen should have been supplied in the calculation, and the measurement result of water quality was actually good.

In the fifth period P5, the continuous aeration time is set to a value (40 minutes) slightly below this necessary minimum continuous aeration time (46 minutes). In this case, there is a possibility that the amount of oxygen is slightly insufficient in calculation by performing intermittent aeration operation. Actually, BOD tends to slightly exceed 5 mg / L (FIG. 8), TN tends to slightly exceed 10 mg / L (FIG. 10), NO ₃ —N decreases, and NH ₄ —N decreases. Shows a tendency to increase to about 5 mg / L (FIG. 11). SS was kept below 5 mg / L. From the viewpoint of maintaining good water quality, the aeration intensity is preferably larger than the minimum aeration intensity necessary.

  As described above, when the blower 500 supplies air to the air diffuser 834, the biological treatment of the water to be treated by the microorganisms carried on the carrying member 835 can be realized. Furthermore, energy can be saved compared with the case where the blower 500 alternately repeats the supply of air and the stop of supply, without stopping the supply of air.

[B. Second Embodiment]
12 and 13 are schematic views showing the configuration of another embodiment of the waste water treatment apparatus. FIG. 12 is a schematic configuration diagram of the waste water treatment apparatus 800x as seen from the side as in FIG. FIG. 13 is a schematic configuration diagram of the waste water treatment apparatus 800x as seen from the AA cross section in FIG. 12 downward as in FIG. The only changes from the waste water treatment apparatus 800 are that the electrolytic cell 900 and the energization unit 950 are added and that the discharge port 864x of the advection pipe 863x is provided in the electrolytic cell 900. The other configuration of the wastewater treatment apparatus 800x is the same as that of the wastewater treatment apparatus 800.

  The electrolytic tank 900 is a box-shaped water treatment tank, and is disposed on the top of the contaminant removal tank 810. The lower part of the electrolytic cell 900 is disposed below the water surface WL (low water level LWL) in the contaminant removal tank 810. An opening 910 is provided at the bottom of the electrolytic cell 900, and the electrolytic cell 900 communicates with the contaminant removal tank 810 through the opening 910. The water level in the electrolytic cell 900 is the same as the water level in the contaminant removal tank 810.

  Instead of the advection pipe 863 of the first embodiment, an advection pipe 863x is connected to the circulation air lift pump 860. The advection pipe 863x extends from the upper part of the vertical pipe 861 to a position above the water surface WL of the electrolytic cell 900 with a gentle downward slope. The water and solids pumped up by the circulating air lift pump 860 are transferred to the electrolytic cell 900 and transferred from the opening 910 of the electrolytic cell 900 to the contaminant removal tank 810.

  In the electrolytic cell 900, two electrode modules 951 and 952 are arranged. The first electrode module 951 has a pair of (two) metal electrodes 951a and 951b arranged apart from each other, and the second electrode module 952 is also a pair of (two) metals arranged apart from each other. Electrodes 952a and 952b are provided. Each of these electrodes 951a, 951b, 952a, and 952b is immersed in the water to be treated. Each electrode module 951 and 952 is electrically connected with an energization unit 950 for energizing. The energization unit 950 receives power supply from a household power source and applies a voltage between the metal electrodes 951a and 951b and between the metal electrodes 952a and 952b. As a result, a current flows between the metal electrodes 951a and 951b and between the metal electrodes 952a and 952b through the water to be treated, and metal ions from the metal electrode on the anode side of the metal electrodes 951a, 951b, 952a, and 952b. Elutes in the water to be treated.

  The elution of metal ions is performed in order to remove the phosphorus component in the water to be treated. As the metal ions, those capable of reacting with a phosphorus component in the water to be treated to generate a water-insoluble phosphorus compound can be employed. For example, iron ions or aluminum ions can be used. As materials for the metal electrodes 951a, 951b, 952a, and 952b, various materials that can elute such metal ions (for example, iron, iron alloy, aluminum, aluminum alloy, iron-aluminum alloy) can be used. The phosphorus component in the water to be treated reacts with metal ions to form a water-insoluble phosphorus compound (for example, iron phosphate). The generated phosphorus compound settles from the electrolytic cell 900 through the opening 910 to the contaminant removal tank 810 and is stored in the contaminant removal tank 810. As a result, the total phosphorus concentration (TP) in the treated water discharged from the waste water treatment apparatus 800x can be reduced.

  The energization unit 950 preferably includes a circuit that reverses the polarity every predetermined time (for example, every 24 hours). By so doing, metal ions can be eluted from the two metal electrodes of each of the electrode modules 951 and 952 approximately evenly.

  Further, as described above, the blower 500 performs intermittent aeration operation. Along with this, water and solids are transferred intermittently from the bottom of the treated water tank 840 to the electrolytic tank 900. Therefore, in the present embodiment, the energization unit 950 is connected to the control unit 520 of the blower 500 and receives a signal indicating the operation state of the control unit 520 from the control unit 520. The energization unit 950 performs energization intermittently in synchronization with the control of gas supply by the control unit 520 using the received signal. Specifically, the energization unit 950 energizes during the time when the control unit 520 supplies gas. Therefore, metal ions can be appropriately eluted in the water transferred to the electrolytic cell 900. Further, the energization unit 950 stops energization during the time when the control unit 520 stops gas supply. Therefore, when water is not transferred to the electrolytic cell 900, it is possible to suppress the unnecessary elution of metal ions. In addition, since energization is performed intermittently, energy can be saved.

  The synchronization between the energization control by the energization unit 950 and the aeration control by the control unit 520 may not be exact. In general, the energization unit 950 energizes at least part of the time that the blower 500 supplies gas, and stops energization at least part of the time that the blower 500 stops supplying gas. That's fine. The energization unit 950 may not be connected to the control unit 520. For example, the energization unit 950 includes a timer and may perform energization control according to the same time schedule as the gas supply control time schedule by the control unit 520.

  Further, the arrangement of the electrolytic cell 900 can be arbitrarily set. For example, the electrolytic cell 900 may be provided in the middle of the advection tube 863x. Further, any water treatment tank upstream of the contact filter bed tank 830 can be adopted as a water transfer destination from the electrolytic tank 900. For example, an anaerobic filter bed tank 820 may be employed.

[C. Modified example]
(1) The configuration of the wastewater treatment apparatus is not limited to the configuration in each of the above embodiments, and various other configurations can be employed. For example, the type of the supporting member provided in the biological treatment tank (for example, the contact filter bed tank 830) is not limited to two types, and may be one type or three or more types. Further, the diffuser 834 is not limited to a pipe provided with a plurality of diffuser holes 834h, and any member (for example, a porous member) capable of generating a large number of bubbles can be employed. Also, the processing flow is not limited to the flow shown in FIG. 1, and various other flows can be employed. For example, a filtration tank may be provided between the biological treatment tank (for example, the contact filter bed tank 830) and the treated water tank 840. Further, instead of the contact filter bed tank 830, a carrier fluid tank in which a supporting member (carrier) for supporting microorganisms flows may be employed. The shape of the biological treatment tank is not limited to the shape surrounding the treated water tank 840 like the contact filter bed tank 830 in FIGS. 3 and 5, and various shapes (for example, a substantially rectangular parallelepiped shape) may be adopted. . In general, various biological treatment tanks having a supporting member for supporting microorganisms and an air diffuser for supplying bubbles containing oxygen to the supporting member can be employed. In either case, energy can be saved while realizing biological treatment by intermittently aeration of the biological treatment tank. Further, in the case where L types of members (L is an integer of 1 or more) for supporting microorganisms are provided in the biological treatment tank, the entire L types of members correspond to “supporting members”.

  Further, the suction port 862 of the circulating air lift pump 860 (FIG. 2) may be disposed at the bottom of a biological treatment tank (for example, the contact filter bed tank 830). In general, as a configuration of the circulating air lift pump 860, from the downstream side of the biological treatment tank or the biological treatment tank, to the upstream treatment tank (for example, the contaminant removal tank 810) arranged on the upstream side of the biological treatment tank, A configuration for transferring water or the like can be employed. In this way, SS generated in the biological treatment tank can be transferred to the upstream treatment tank. In any case, the suction port 862 of the circulating air lift pump 860 is preferably arranged at the bottom of the water treatment tank. If it carries out like this, SS which settled to the bottom part can be transferred efficiently.

(2) When fixing a supporting member in a biological treatment tank, it is preferable to employ | adopt the following structures. That is, when the air diffuser (for example, the air diffuser 834) and the support member (for example, the support member 835) are viewed from above to below, the blower 500 supplies gas to the air diffuser. It is preferable that the air bubbles rise from almost the entire upper portion of the region where the supporting member is disposed. By so doing, it is possible to reduce the possibility that a portion where bubbles are not supplied (referred to as “bubble-free portion”) will be generated in the carrier member, and thus biological treatment can be realized appropriately. For example, when viewed from the top to the bottom, it is preferable not to arrange the support member at a position far from the air diffuser (particularly the air diffuser hole 834h). When rising bubbles are observed from 80% or more of the upper portion of the region where the supporting member is disposed when viewed from the upper side to the lower side, “almost all of the upper portion of the region where the supporting member is disposed. It can be said that the bubble rises. However, the region where the rising bubbles are observed may be less than 80% of the upper portion of the region where the carrier member is disposed.

  Further, like the air diffuser 834 in FIG. 6, the air diffuser has a plurality of air diffusers arranged in a distributed manner in the range of the bottom of the region where the support member is arranged when viewed from above. It is preferable to have pores. By so doing, it is possible to supply bubbles to almost the entire bottom portion of the support member, so that the possibility of generating a bubble-free portion can be reduced.

  Moreover, it is preferable that the supporting member is disposed over almost the entire area of the biological treatment tank at least at a height in the region where the supporting member is disposed. In other words, as in the swirling flow type, the supporting member is not disposed only in one of the region in which the water to be treated rises and the region in which the water to be treated descends. Then, it is preferable to arrange | position a supporting member over the whole region of a biological treatment tank. In this way, since the capacity of the biological treatment tank can be effectively used for biological treatment, appropriate biological treatment can be realized. For example, in the embodiment shown in FIG. 3 and FIG. 5, the contact material 832 is disposed over almost the entire area of the contact filter bed 830 at least partially in the region where the contact material 832 is disposed. Has been. In addition, if the area | region where the supporting member is arrange | positioned is 80% or more of the horizontal surfaces in a biological treatment tank, it can be said that "the supporting member is arrange | positioned over the substantially whole region of a biological treatment tank." .

(3) The amount of air flow during aeration (driving) in the intermittent aeration operation of the biological treatment tank is sufficient for air bubbles to rise from almost the entire upper area of the area where the supporting member is disposed in the biological treatment tank. It is preferable to adopt an air volume. By doing so, the possibility of the occurrence of a bubble-free portion can be reduced, and thus biological treatment can be appropriately realized. In particular, when the supporting member is fixed in the biological treatment tank, if a bubble-free portion is generated, it is difficult to eliminate the bubble-free portion naturally. Therefore, in order to suppress the occurrence of a bubble-free portion, it is preferable to employ an air volume sufficient for bubbles to rise from almost the entire upper portion of the region where the carrier member is disposed. Such air volume may be determined experimentally, for example. Moreover, although the air volume determined in this way may exceed the minimum air volume required for the aerobic treatment, energy can be saved by performing intermittent aeration operation.

(4) It is preferable to provide the septic tank with a peak cut mechanism that suppresses an increase in the amount of outflow per unit time from the biological treatment tank (particularly the aerobic treatment tank) caused by the peak inflow. The peak cut mechanism is not limited to the discharge air lift pump 870 of the embodiment of FIG. 2, and various configurations can be employed. For example, a septic tank receives a biological treatment tank (particularly an aerobic treatment tank, for example, a contact filter bed tank 830) and inflow water (also referred to as raw water) to the septic tank, and supplies the received water to the aerobic treatment tank. In the case of having a pre-treatment section (for example, the entire contaminant removal tank 810 and anaerobic filter bed tank 820), the aerobic treatment tank (for example, the contact filter bed tank 830) is covered. An air lift pump that transfers treated water in small amounts can be used. Moreover, you may employ | adopt the weir (for example, V-shaped weir or a small hole) which restrict | limits the transfer flow rate per unit time from a front | former process part to an aerobic treatment tank. Providing such a peak cut mechanism can reduce the possibility of untreated water flowing out of the aerobic treatment tank.

  FIG. 14 is a schematic view showing another example of a wastewater treatment tank having a peak cut mechanism. A treatment using intermittent aeration similar to the above-described embodiment may be applied to the waste water treatment apparatus 1800. FIG. 14 shows a schematic configuration similar to that of FIG. 2 when the wastewater treatment apparatus 1800 is viewed from the side. This wastewater treatment apparatus 1800 is arranged in order from the upstream side (left side in FIG. 14), an inlet 1802, a sedimentation separation tank 1810, an anaerobic filter bed tank 1820, an aerobic filter bed tank 1830, a treated water tank 1840, a disinfection tank 1850, a flow. It has an outlet 1804. The aerobic filter bed tank 1830 is disposed on the + Y direction side of the treated water tank 1840. In FIG. 14, the aerobic filter bed tank 1830 and the treated water tank 1840 are shown in an overlapping manner.

  Waste water flows into the waste water treatment apparatus 1800 from the inflow port 1802. The water after the impurities are separated (removed) in the sedimentation separation tank 1810 is transferred to the anaerobic filter bed tank 1820 through the empty portion at the top of the partition plate 1819. The anaerobic filter bed tank 1820 is provided with a filter medium 1822 for attaching anaerobic microorganisms. The anaerobic filter bed tank 1820 is provided with a transfer air lift pump 1827. The transfer air lift pump 1827 continuously transfers the water treated in the anaerobic filter bed tank 1820 to the upper part of the aerobic filter bed tank 1830.

  The aerobic filter bed tank 1830 has two parts, a contact aeration part and a biological filtration part (not shown). The contact aeration unit includes a contact material for attaching aerobic microorganisms, and an air diffuser disposed below the contact material. The biological filtration unit has a filtering material for capturing solid matter (such as suspended matter (SS)). The treated water flowing into the aerobic filter bed tank 1830 circulates between the contact aeration unit and the biological filtration unit.

  The water treated in the aerobic filter bed tank 1830 is transferred to the treated water tank 1840 through a lower opening (not shown). A transfer pipe (not shown) for transferring water to the disinfection tank 1850 is provided on the upper part of the treated water tank 1840. The transfer pipe is provided with a weir. This weir restricts the transfer rate per unit time from the treated water tank 1840 to the disinfection tank 1850. The water sterilized in the sterilization tank 1850 is discharged to the outside of the waste water treatment apparatus 1800 through the outlet 1804.

  The treated water tank 1840 is provided with a circulating air lift pump 1849. The circulation air lift pump 1849 sucks water and solids from the bottom of the treated water tank 1840 and transfers them to the precipitation separation tank 1810. A return weir 1828 is provided above the aerobic filter bed tank 1830. Of the amount of water transferred to the aerobic filter bed tank 1830 by the transfer air lift pump 1827, the amount of water circulated by the circulation air lift pump 1849 and the amount of water transferred from the treated water tank 1840 to the disinfection tank 1850 (the amount of water discharged from the waste water treatment apparatus 1800) Excess water except for the same) is returned to the anaerobic filter bed tank 1820 through the return weir 1828. As a result, water is continuously transferred from the anaerobic filter bed tank 1820 to the aerobic filter bed tank 1830 by approximately a constant amount.

  The suction port 1827i of the transfer air lift pump 1827 is disposed at the height of the low water level LWLx. Therefore, the lowest water level of the sedimentation separation tank 1810 and the anaerobic filter bed tank 1820 is this low water level LWLx. Further, the waste water treatment apparatus 1800 is configured such that no overflow occurs even if the water level rises to a high water level HWLx higher than the low water level LWLx. At the peak inflow, the water level can rise from the low water level LWLx. When the water level rises, the water level gradually falls to the low water level LWLx as the advection of water from the treated water tank 1840 to the disinfection tank 1850 proceeds. Thus, even when the water level fluctuates between the low water level LWLx and the high water level HWLx, the amount of circulating water by the circulating air lift pump 1849, the amount of water transferred to the disinfection tank 1850 through a transfer pipe (not shown), and the anaerobic filter Each of the amount of water transferred from the floor tank 1820 to the aerobic filter bed tank 1830 (substantial amount of water excluding the amount returned from the return weir 1828) (the amount of water per unit time) is approximately Maintained at a constant amount. As a result, the aerobic filter bed tank 1830 can continue a stable process.

(5) The time of one cycle of intermittent aeration is not limited to 70 minutes, and various times can be adopted. For example, a shorter time (for example, 20 to 60 minutes) may be employed, or a longer time (for example, 2 to 10 hours) may be employed. Various times can be adopted as the continuous stop time and the continuous aeration time.

  As the time of one cycle, it is preferable to employ a time of less than half a day. The reason for this is as follows. For example, as a large-scale wastewater treatment facility using activated sludge, a facility having a flow rate adjustment tank provided on the upstream side of an aeration tank is used. By using the flow rate adjusting tank, it is possible to control the transfer flow rate per unit time from the flow rate adjusting tank to the aeration tank. By increasing the size of the flow rate adjustment tank (for example, by securing a capacity capable of storing the wastewater for one day), the degree of freedom in controlling the advection pattern to the aeration tank can be increased. Here, according to the controlled advection pattern, it is possible to employ a processing method in which an aeration tank containing activated sludge is intermittently aerated. In order to control the amount of activated sludge in the aeration tank, a sedimentation tank may be provided on the downstream side of the aeration tank, and a part of the sludge collected in the sedimentation tank may be returned to the aeration tank. Here, as the time of one cycle of intermittent aeration, various times can be adopted according to the advection pattern. However, such a treatment method is different from the above-described embodiment in that activated sludge is used without using a supporting member for supporting microorganisms and that a large flow rate adjusting tank is used. Yes. Therefore, in the above embodiment, it is preferable to determine the parameter of intermittent aeration (for example, the time of one cycle) in consideration of these differences.

  Household septic tanks accept biological treatment tanks (especially aerobic treatment tanks, for example, contact filter bed tank 830) and inflow water (raw water) to the septic tanks, and supply the received water to the aerobic treatment tanks. A pre-treatment section (for example, the entire contaminant removal tank 810 and anaerobic filter bed tank 820). Usually, the configuration of the upstream treatment unit is a large water treatment tank (for example, a flow rate adjustment tank capable of storing one day's worth of inflow water) that can completely absorb the fluctuation of the inflow amount per unit time of the inflow water. A small configuration that does not have is adopted. For example, like the contaminant removal tank 810 and the anaerobic filter bed tank 820 in FIG. 2, the pre-treatment unit supplies the water to be treated to the aerobic treatment tank by a so-called extrusion flow. Therefore, the supply amount (inflow amount) per unit time of the water to be treated to the aerobic treatment tank varies according to the fluctuation of the inflow amount per unit time of the inflow water. And normally, since raw | natural water flows irregularly into a septic tank over the wide range of a day, to-be-processed water will flow into a biological treatment tank irregularly over the wide range of a day. Therefore, when performing regular intermittent aeration operation with a long cycle of more than half a day, there is a possibility that appropriate biological treatment cannot be performed. For example, when a large amount of raw water flows within the time when the aeration is stopped, a large amount of water to be treated flows into the biological treatment tank, but there is a possibility that appropriate aerobic treatment cannot be performed due to lack of oxygen. . Accordingly, it is preferable to repeat the intermittent aeration cycle a plurality of times while the water to be treated passes through the septic tank. Usually, since the total capacity of the septic tank is equal to or more than the daily average amount of sewage, if the time of one cycle is less than half a day, at least two cycles can be realized while the water to be treated passes through the septic tank. . By doing so, it is possible to reduce the possibility that the water to be treated passes through the aerobic treatment tank without being subjected to the aerobic treatment while the aeration of the aerobic treatment tank is stopped.

  Moreover, it is preferable that the time of 1 period is below the residence time of an aerobic processing tank. By doing so, since at least one cycle is realized while the water to be treated passes through the aerobic treatment tank, the water to be treated is not aerobically treated while the aeration of the aerobic treatment tank is stopped. The possibility of passing through the aerobic treatment tank can be reduced. For example, the residence time of the contact filter bed tank 830 of the test tank is 11.6 hours. Therefore, when adopting the above test tank, it is preferable that the time of one cycle is 11.6 hours or less.

  Moreover, when a part of water is transferred (circulated) from the aerobic treatment tank or the downstream side of the aerobic treatment tank to the upstream side of the aerobic treatment tank, it passes through the aerobic treatment tank. The amount of water is the sum of the amount of water flowing into the septic tank and the amount of water circulating. For example, in the test tank described above, the design value of the amount of circulating water per day by the circulating air lift pump 860 is 4 to 6 times the inflowing water amount (daily average sewage amount). Therefore, in order to reduce the possibility that the water to be treated will pass through the aerobic treatment tank without being subjected to the aerobic treatment, the time of one cycle is the residence time of the aerobic treatment tank. It is preferably less than or equal to the time obtained by dividing by the actual amount of water passing through (the amount of water when the daily average amount of sewage is 1). For example, in the above test tank, the residence time of the contact filter bed tank 830 is 11.6 hours. When the circulating water amount is four times the inflowing water amount, the actual water amount passing through the aerobic treatment tank is “5”. In this case, the time of one cycle is preferably 11.6 hours / 5 = 2.3 hours or less. If it carries out like this, the possibility that to-be-processed water will pass an aerobic treatment tank without an aerobic treatment can be reduced.

  Moreover, it is preferable that continuous stop time is below the residence time of an aerobic treatment tank. By doing so, it is possible to reduce the possibility that the water to be treated passes through the aerobic treatment tank without being subjected to the aerobic treatment while the aeration of the aerobic treatment tank is stopped. For example, the residence time of the contact filter bed tank 830 of the test tank is 11.6 hours. Therefore, when employing the above test tank, it is preferable that the continuous stop time is 11.6 hours or less.

  In addition, when a part of water is transferred (circulated) from the aerobic treatment tank or the downstream side of the aerobic treatment tank to the upstream side of the aerobic treatment tank, the water to be treated is subjected to the aerobic treatment. In order to reduce the possibility of passing through the aerobic treatment tank without being continuous, the continuous stop time is determined based on the residence time of the aerobic treatment tank, the actual amount of water passing through the aerobic treatment tank (daily average amount of sewage) It is preferable that the time is equal to or less than the time obtained by dividing by (the amount of water when 1 is 1). For example, in the above test tank, the residence time of the contact filter bed tank 830 is 11.6 hours. When the circulating water amount is four times the inflowing water amount, the actual water amount passing through the aerobic treatment tank is “5”. In this case, the continuous stop time is preferably 11.6 hours / 5 = 2.3 hours or less.

  When the septic tank having the above-described peak cut mechanism is employed, it is particularly preferable that the continuous stop time of the intermittent aeration operation is equal to or less than the residence time by the peak cut mechanism. Here, the residence time by the peak cut mechanism is the amount of water that can be temporarily stored by the peak cut mechanism (for example, the capacity between the low water level LWL and the high water level HWL) / daily average sewage amount * 24 hours. In this way, when peak inflow occurs, the possibility that a large amount of water to be treated passes through the aerobic treatment tank without aerobic treatment while the aeration of the aerobic treatment tank stops. it can. As a result, it is possible to appropriately perform the aerobic process. In addition, if the peak cut mechanism such as air lift pump, weir, small hole, etc. cannot fully absorb the fluctuation of inflow per unit time of raw water, according to the fluctuation of inflow per unit time of raw water, The amount of outflow per unit time from the aerobic treatment tank can vary.

(6) The ratio of the continuous aeration time to the time of one cycle of intermittent aeration can be set to various ratios. Here, the smaller the ratio of the continuous aeration time, the more energy can be saved, but there is a higher possibility of problems such as oxygen shortage. Therefore, it is preferable to reduce the ratio of the continuous aeration time within a range where the aerobic treatment can be appropriately realized. For example, you may determine the ratio of continuous aeration time based on the experiment which actually measures the quality of discharged water. Instead of this, a continuous aeration time capable of realizing an appropriate aerobic process may be obtained by calculation. For example, according to the method described in the first embodiment, an aeration intensity (referred to as “necessary aeration intensity”) that realizes the required K _L a is calculated. And the ratio of the continuous aeration time in which the average value of the aeration intensity when the intermittent aeration operation is performed becomes the required aeration intensity may be adopted as the lower limit value. For example, in the first embodiment, the lower limit value of the ratio of the continuous aeration time is 3.6 / 5.5 = 0.65. In order to realize an appropriate aerobic treatment, it is preferable that the actual ratio of continuous aeration time is equal to or greater than the lower limit.

(7) In order to advance the denitrification, it is preferable to provide an air lift pump that returns (circulates) the water aerobically treated in the biological treatment tank to the water treatment tank for anaerobic treatment. For example, in the above embodiment, the circulating air lift pump 860 transfers the water that has been aerobically treated in the contact filter bed tank 830 to the anaerobic filter bed tank 820 that performs anaerobic treatment through the contaminant removal tank 810. . Here, in order to simplify the configuration, the air lift pump can operate by receiving a gas supply from a gas supply unit (for example, the blower 500) that supplies gas to the diffuser of the biological treatment tank. preferable. In this case, it is preferable that the amount of transfer (circulated water amount) per unit time by the air lift pump is larger as the ratio of the continuous stop time of intermittent aeration is higher. In this way, even if the ratio of the continuous stop time is high, it is possible to suppress the denitrification amount from being reduced due to the insufficient circulating water amount. In order to suppress a decrease in the amount of denitrification, the amount of circulating water is such that the total amount of circulating water per day is at least twice (more preferably, at least 2.5 times) the daily average amount of sewage. Is preferably adjusted.

  Moreover, when the biological treatment tank using a supporting member is adopted, an effect of denitrification can be expected by performing intermittent aeration operation. For example, when the activated sludge method is adopted, since the microorganism distribution (sludge concentration) in the treatment tank is approximately uniform, in order to proceed with denitrification, the dissolved oxygen amount (DO) in the treatment tank is approximately It was necessary to lower it to zero. On the other hand, in the biological treatment tank using the supporting member, since the distribution of microorganisms is non-uniform (because microorganisms are unevenly distributed in the region where the supporting member exists), when the aeration is stopped, the dissolved oxygen amount ( There is a possibility that denitrification proceeds due to locally low DO). Therefore, even if the continuous stop time is short, denitrification may proceed locally.

  The gas supply unit (for example, the blower 500 (control unit 520)) has an intermittent aeration operation pattern in which the ratio of the continuous stop time with respect to the time of one cycle of intermittent aeration (the ratio of the continuous aeration time) is You may employ | adopt the pattern which changes according to it. For example, the amount of water flowing into the septic tank is generally relatively small at night and relatively large during the day. Therefore, the first period of the day (for example, the period from 23:00 to 6:00 the next morning) is compared with the second period (for example, the period from 6:00 to 23:00) that is the remaining period. The ratio of the continuous stop time to the time of one cycle of intermittent aeration may be large. Thus, if the ratio of the time to stop aeration is increased in the first period when the amount of inflow water is small, energy can be saved while suppressing the deterioration of water quality.

  As mentioned above, although this invention was demonstrated based on the Example and the modification, Embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention.

500 ... Blower, 502 ... Connection pipe, 510 ... Drive unit, 520 ... Control unit, 610 ... Air supply port, 620 ... Air diffuser valve, 622 (622p, 622m). ..Air supply pipe, 630 ... circulation valve, 632 ... Air supply pipe, 640 ... Discharge valve, 800, 800x ... Wastewater treatment device, 801 ... Bath body, 802 ... Flow Inlet, 803 ... Partition plate (side wall), 804 ... Outlet, 810 ... Contaminant removal tank, 812 ... Inflow baffle, 814 ... Advection opening, 820 ... Anaerobic filter bed tank , 822 ... Filter medium, 824 ... Advection opening, 830 ... Contact filter bed tank, 832 (832p, 832m) ... Contact material, 833 (833p, 833m) ... Aerobic filter medium, 834 ( 834p, 834m) ... Aeration device, 834a ... Loop part, 834b ... Linear part, 834h ... Aeration hole, 835 ... Supporting member, 836 ... Advection opening, 839 ... 840 ... treated water tank, 841 ... first side wall, 842 ... second side wall, 843 ... third side wall, 844 ... fourth side wall, 845 ... bottom Wall, 849 ... Hopper part, 849L ... Lower part, 850 ... Disinfection tank, 854 ... Drug cylinder, 860 ... Circulating air lift pump, 861 ... Vertical pipe, 862 ... Inhalation Mouth, 863, 863x ... advection tube, 864, 864x ... outlet, 870 ... outlet air lift pump, 872 ... inlet, 874 ... outlet, 900 ... electrolytic cell, 910 ... Opening, 950 ... Current-carrying part, 951, 952 ... Electrode module, 951a, 951b, 952a, 952b ... Metal electrode, 1800 ... Wastewater treatment device, 1802 ... Inlet, 1804 ... Outlet, 1810 ... Precipitation separation tank, 1819 ... Partition plate, 1820 ... Anaerobic filter bed tank, 1822 ... Filter medium, 1827 ... Transfer air lift pump, 18 7i ... inlet, 1828 ... weir, 1830 ... aerobic filter bed tank, 1840 ... treatment water tank, 1849 ... circulating air lift pump, 1850 ... disinfecting bath

Claims (6)

Wastewater treatment equipment,
A biological treatment tank for biologically treating the water to be treated;
A support member disposed in the biological treatment tank for supporting microorganisms;
An air diffuser disposed below the support member of the biological treatment tank and supplying bubbles containing oxygen to the support member;
A gas supply unit that alternately repeats the supply of gas containing oxygen to the aeration unit and the stop of the supply;
A pre-treatment unit for receiving inflow water to the wastewater treatment device and supplying the accepted water to the biological treatment tank;
Bei to give a,
The pre-treatment unit is configured such that the supply amount of the water per unit time to the biological treatment tank varies according to the variation of the inflow amount per unit time of the inflow water,
The gas supply unit is an air volume that is an amount of gas per unit time, and an air volume that can obtain an oxygen amount necessary to achieve a target water quality by repeating the supply of the gas and the stop of the supply. And supplying the gas with an air volume larger than that required to obtain the required oxygen amount when the gas supply is continuously performed without stopping the gas supply.
Wastewater treatment equipment.   A wastewater treatment apparatus according to claim 1,
  The gas supply unit supplies air as the gas containing oxygen to the aeration unit,
  The time for continuously stopping the supply of air by the gas supply unit is less than the residence time of the biological treatment tank,
  Wastewater treatment equipment. The wastewater treatment apparatus according to claim 1 or 2 ,
The carrying member is fixed in the biological treatment tank,
The air diffuser has a plurality of air diffusers arranged in a range of the bottom of the region in which the carrier member is disposed when viewed from above downward.
Wastewater treatment equipment. A wastewater treatment apparatus according to claim 3 ,
When the gas diffuser and the carrier member are viewed from above from below, the gas supply unit supplies the gas to the gas diffuser, so that the upper part of the region where the carrier member is disposed. The bubble is configured to rise from almost the entire area of
Wastewater treatment equipment. A wastewater treatment apparatus according to any one of claims 1 to 4,
The gas supply unit alternately repeats the supply of the gas and the stop of the supply at a cycle shorter than half a day,
Wastewater treatment equipment. The wastewater treatment apparatus according to any one of claims 1 to 5, further comprising:
An upstream treatment tank disposed upstream of the biological treatment tank;
An air lift pump for transferring water from the downstream side of the biological treatment tank or the biological treatment tank to the upstream treatment tank by receiving the supply of the gas from the gas supply unit;
A pair of metal electrodes immersed in transfer water transferred by the air lift pump;
In order to react with the phosphorus component in the transfer water, by energizing the pair of metal electrodes, an energization unit for eluting the metal ions of the metal electrode into the transfer water;
Including
The energization part is
The energization is performed at least during part of the time that the gas supply unit is supplying the gas,
The energization is stopped at least during part of the time when the gas supply unit stops supplying the gas,
Wastewater treatment equipment.