JP5329495B2 - Biological wastewater treatment equipment - Google Patents

Description

The present invention relates to a biological waste water treatment equipment for processing waste water using the microbial sludge.

  A biological wastewater treatment apparatus that removes harmful substances in wastewater using microbial sludge that decomposes harmful substances is known (see, for example, Patent Document 1).

Japanese Patent No. 4001514

  Here, microbial sludge requires a hydrogen donor such as methanol when decomposing harmful substances. For this reason, in the biological wastewater treatment apparatus, a hydrogen donor is supplied to the wastewater. Moreover, microbial sludge grows with the decomposition of organic substances. For this reason, in the biological waste water treatment apparatus, surplus sludge is disposed of. Under such circumstances, in the biological wastewater treatment apparatus, the cost for the hydrogen donor to be supplied and the cost for disposal of excess sludge have been problems.

The present invention has been made to solve the above problems, and aims to provide a supply amount and that can reduce the amount of generated excess sludge biological waste water treatment equipment of the hydrogen donor To do.

  Here, the present inventors have found the following phenomenon. Microbial sludge not only has the property of decomposing and multiplying harmful substances in wastewater, but also has the property of absorbing and growing dissolved oxygen in wastewater, and consumes hydrogen donors when absorbing dissolved oxygen. . For this reason, when the amount of dissolved oxygen in the wastewater increases (the concentration of dissolved oxygen in the wastewater increases), a lot of hydrogen donors are consumed to absorb the dissolved oxygen, and a lot of excess sludge is generated due to the absorption of the dissolved oxygen. . The inventors of the present invention have arrived at the present invention based on the above events.

  Therefore, a biological wastewater treatment apparatus according to the present invention is a biological wastewater treatment apparatus that treats wastewater using microbial sludge. The biological wastewater treatment apparatus has a sealed first tank, and the treated water that is wastewater is the first tank. A conditioning apparatus for supplying a hydrogen donor to the treated water and discharging the treated water to the outside of the first tank, and a microbial sludge bed containing the microorganisms agglomerated in a granular form. There are two tanks, the treated water discharged outside the first tank is introduced into the second tank, the treated water is raised to form an upward flow in the second tank, and the treated water is treated. It is characterized by comprising a reaction device that discharges water as the outside of the second tank, and a return line that returns a part of the treated water discharged outside the second tank to the first tank.

According to such biological wastewater treatment equipment, since the first layer and the second tank is sealed, the water to be treated in each vessel, will not to blend oxygen in the air surrounding each tank . And the to-be-processed water introduce | transduced in the 2nd tank raises the inside of a 2nd tank, and countercurrent-contacts with a microorganisms sludge bed. At this time, since dissolved oxygen in the wastewater is absorbed by the action of the microbial sludge bed, the dissolved oxygen concentration of the treated water discharged to the outside of the second tank becomes low. Since this treated water is returned to the first tank by the return line and mixed with the treated water in the first tank, the dissolved oxygen concentration of the treated water in the first tank becomes low. As a result, the dissolved oxygen concentration of the water to be treated discharged to the outside of the first tank and introduced into the second tank is lowered, and the hydrogen donor consumed for absorption of dissolved oxygen and the absorption of dissolved oxygen The excess sludge produced is reduced. Further, since the hydrogen donor remaining in the treated water discharged from the second tank is returned to the first tank by the return line and reused, the supply amount of the hydrogen donor is reduced.

Further, Runode comprises a diffuser means for supplying an oxygen-containing gas into the lower portion of the second tank, or the like at the time of or during stopping reactor startup, the oxygen-containing gas is supplied to the lower portion of the second tank, microbial sludge Floor hardening and anaerobic rot can be prevented.

Thus, according to the present invention, it is possible to provide a biological wastewater treatment equipment which can reduce the generation amount of the supply amount and the excess sludge hydrogen donor.

It is a schematic block diagram of the biological waste water treatment apparatus which employ | adopted the biological waste water treatment method which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the biological waste water treatment apparatus which employ | adopted the biological waste water treatment method which concerns on 2nd Embodiment of this invention.

  Hereinafter, a preferred embodiment of a biological wastewater treatment apparatus employing a biological wastewater treatment method according to the present invention will be described with reference to the accompanying drawings. Note that, in each drawing, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  First, a first embodiment of a biological wastewater treatment apparatus according to the present invention will be described. FIG. 1 is a schematic configuration diagram of a biological wastewater treatment apparatus employing the biological wastewater treatment method according to the first embodiment of the present invention. In this embodiment, the biological wastewater treatment apparatus is a biological denitrification. The processing apparatus will be described.

  The biological denitrification treatment apparatus 100 includes a raw water adjustment tank 1 that stores treated water that is wastewater, a conditioning apparatus 2 that supplies a hydrogen donor (methanol in this case) to the treated water, and methanol. And a reactor 3 that performs denitrification treatment of water to be treated.

  In addition, the biological denitrification treatment apparatus 100 includes a line L1 for sending water to be treated from the raw water adjustment tank 1 to the conditioning device 2, a line L2 for sending water to be treated from the conditioning device 2 to the reaction device 3, and a denitrification treatment. The treated water is treated as treated water, the line L3 is sent to the subsequent stage, the line L4 is a return line for returning a part of the treated water from the reactor 3 to the conditioning device 2, and methanol is supplied to the conditioning device 2. And a line L6 for sending gas from the conditioning device 2 and the reaction device 3. The line L1 and the line L2 are provided with a pump P1 for pressure feeding.

  The conditioning device 2 has a conditioning tank 4 that is a sealed first tank. The conditioning device 2 introduces the water to be treated discharged from the raw water adjustment tank 1 into the conditioning tank 4 via the line L1. Moreover, the conditioning apparatus 2 introduce | transduces methanol into the conditioning tank 4 via the line L5, and supplies it to to-be-processed water. Furthermore, the conditioning device 2 discharges the gas generated in the conditioning tank 4 to the line L6.

  A pH meter 5 is attached to the conditioning tank 4. The pH meter 5 measures the pH of the liquid in the conditioning tank 4. Here, when the measured value of the pH meter 5 is not within the predetermined range, a pH adjuster (here, hydrogen chloride) can be supplied to the liquid in the conditioning tank 4 via the line L5. The predetermined range is a range (for example, pH 6 to 9.5) suitable for inhabiting microorganisms (described later).

  The reaction apparatus 3 has a reaction tank 6 that is a sealed second tank. A microorganism sludge bed 9 containing microorganisms aggregated in a granular form (here, denitrifying bacteria) is accommodated in the lower part of the reaction tank 6. Under anaerobic conditions, a denitrifying bacterium decomposes harmful substances (here, nitrogen compounds) in water to be treated to generate gas (here, nitrogen gas) and grows. At that time, the denitrifying bacteria consume methanol. In addition, denitrifying bacteria absorb the dissolved oxygen in the treated water and grow. At that time, denitrifying bacteria consume methanol.

  The reactor 3 introduces water to be treated from the conditioning tank 4 to the lower part of the reaction tank 6 via the line L2, and raises the water to be treated to form an upward flow in the reaction tank 6. The treated water rising in the reaction tank 6 is in countercurrent contact with the microbial sludge bed 9 and denitrified by the action of the denitrifying bacteria contained in the microbial sludge bed 9 (treatment that decomposes nitrogen compounds and generates nitrogen gas). ) Is made. Thus, the reaction vessel 6 constitutes a USB (Upflow Sludge Blanket) reaction vessel.

  A gas-solid-liquid separator 8 is provided in the upper part of the reaction tank 6. The gas-solid liquid separation unit 8 separates solids such as microorganisms, gas such as nitrogen gas generated in the reaction tank 6, and treated water subjected to denitrification treatment. The reaction apparatus 3 discharges the treated water separated by the gas-solid-liquid separation unit 8 to the outside of the reaction tank 6 through the line L3. Moreover, the reactor 3 returns a part of the treated water separated by the gas-solid-liquid separator 8 to the conditioning tank 4 via the line L4. Moreover, the reaction apparatus 3 discharges the gas separated by the gas-solid-liquid separation unit 8 to the line L6.

  The biological denitrification apparatus 100 includes an air diffuser 7 that supplies an oxygen-containing gas to the lower part of the reaction tank 6. The air diffuser 7 has a plurality of nozzles 7a provided in the lower part of the reaction tank 6, and a line L7 for supplying an oxygen-containing gas to the nozzles 7a. In addition, the air diffuser 7 has an opening / closing device (not shown) that freely switches whether or not the oxygen-containing gas is supplied.

  Next, the operation of the biological denitrification apparatus 100 configured as described above will be described. The treated water accommodated in the raw water adjustment tank 1 is introduced into the conditioning tank 4, and methanol is supplied to the treated water. Since the conditioning tank 4 is sealed, oxygen in the air surrounding the conditioning tank 4 does not dissolve in the water to be treated.

  The treated water supplied with methanol in the conditioning tank 4 is introduced into the reaction tank 6 and rises in the reaction tank 6. At this time, the microbial sludge bed 9 is counter-flow contacted and denitrified by the action of denitrifying bacteria contained in the microbial sludge bed 9. In addition, dissolved oxygen in the water to be treated is absorbed by the action of denitrifying bacteria. Since the reaction tank 6 is sealed, oxygen in the air surrounding the reaction tank 6 does not dissolve in the water to be treated. The treated water that has risen in the reaction tank 6 and has been denitrified is separated from nitrogen gas, microorganisms, and the like by the gas-solid-liquid separation unit 8, and discharged out of the reaction tank 6.

  A part of the treated water discharged from the reaction tank 6 is returned to the conditioning tank 4 via the line L4 and mixed with the treated water in the conditioning tank 4. Since the dissolved oxygen concentration of the treated water is lowered by the action of the denitrifying bacteria, the dissolved oxygen concentration of the treated water mixed with the treated water is lowered. As a result, the dissolved oxygen concentration of the water to be treated that is discharged out of the conditioning tank 4 and introduced into the reaction tank 6 becomes low, and methanol that is consumed for the absorption of dissolved oxygen and surplus that accompanies the absorption of the dissolved oxygen. Sludge is reduced.

  Moreover, since the methanol remaining in the treated water discharged from the reaction tank 6 is returned to the conditioning tank 4 by the line L4 and reused, the supply amount of methanol is reduced.

  Thus, in this embodiment, the supply amount of methanol and the generation amount of excess sludge can be reduced.

  In addition, when the reaction apparatus 3 stops and there exists a possibility of hardening of the microbial sludge bed 9 or anaerobic decay, oxygen-containing gas is supplied to the lower part in the reaction tank 6 by the air diffuser 7. The supply of the oxygen-containing gas by the air diffuser 7 is performed, for example, when the reaction device 3 is stopped or started. Thereby, hardening of the microbial sludge bed 9 and anaerobic decay can be prevented. The air diffuser 7 has an open / close device that freely switches whether or not the oxygen-containing gas is supplied, and anaerobic conditions necessary for the denitrification treatment are maintained.

  Moreover, since the reaction tank 6 comprises a USB reaction tank and can make a denitrification process high load, the installation area of the reaction tank 6 can be made small.

  Next, a second embodiment of the biological waste water treatment apparatus according to the present invention will be described. FIG. 2 is a schematic configuration diagram of a biological wastewater treatment apparatus adopting the biological wastewater treatment method according to the second embodiment of the present invention. In this embodiment, the biological wastewater treatment apparatus is biologically detached. It demonstrates as a nitrogen treatment apparatus.

  The biological denitrification apparatus 200 according to the second embodiment is different from the biological denitrification apparatus 100 according to the first embodiment in that a hydrogen donor (here, methanol) remaining in the treated water discharged to the line L3. ) Is removed by microbial sludge.

  The hydrogen donor removing apparatus 20 includes an aeration tank 21 that performs a hydrogen donor removing process, and a precipitation tank 22 that separates and precipitates microbial sludge from the liquid to be treated. In addition, the hydrogen donor removing device 20 has a line L21 for sending the liquid to be treated from the aeration tank 21 to the precipitation tank 22, a line L22 for sending the treatment liquid from the precipitation tank 22 to the subsequent stage, and a line L22 from the precipitation tank 22 to the aeration tank 21 to be described later. And a line L23 for returning the aggregated floc.

  The aeration tank 21 accommodates microbial sludge and introduces treated water discharged from the reaction tank 6 as a liquid to be treated. The microbial sludge accommodated in the aeration tank 21 consumes methanol and grows under aerobic conditions. A plurality of nozzles 21 a are provided in the lower part of the aeration tank 21, branching off from the line L <b> 7, and supplying oxygen-containing gas into the aeration tank 21. The liquid to be treated and the microbial sludge in the aeration tank 21 are agitated by the oxygen-containing gas supplied from the nozzle 21a, and aerobic treatment of methanol is performed.

  The sedimentation tank 22 is called a high-speed coagulation sedimentation tank, and has a mixing chamber 23 therein. The mixing chamber 23 is arranged in an upright state in the settling tank 22 and contains a liquid to be treated containing microbial sludge, adds a flocculant to the liquid to be treated, and stirs and mixes by rotation of the stirring blade 23b. It forms the flocs of microbial sludge. The liquid to be processed is introduced into the mixing chamber 23 from the aeration tank 21 via the line L21. At the bottom of the mixing chamber 23, there is provided a horizontal distribution pipe 23a that extends radially and rotates, and the liquid to be treated in the mixing chamber 23 is discharged from the distribution pipe 23a together with the aggregation floc. The agglomerated floc discharged from the distribution pipe 23a is separated from the liquid to be treated and precipitates, and the liquid to be treated rises to become the treatment liquid. A concentrated sludge layer 24 of coagulated flocs is formed in the lower part of the settling tank 22, and a supernatant layer 25 of the processing liquid is formed in the upper part. The processing liquid of the supernatant layer 25 is discharged from the sedimentation tank 22 to the subsequent stage via the line L22. The aggregated floc of the concentrated sludge layer 24 is returned to the aeration tank 21 through the line L23.

  Next, the operation of the biological denitrification apparatus 200 configured as described above will be described. The treated water discharged from the reaction tank 6 is introduced into the aeration tank 21 as a liquid to be treated, and the methanol remaining in the liquid to be treated is removed. The liquid to be treated from which methanol has been removed in the aeration tank 21 is separated into the concentrated sludge layer 24 and the supernatant layer 25 in the precipitation tank 22, and the treatment liquid in the supernatant layer 25 is appropriately discharged. The aggregated floc of the concentrated sludge layer 24 is returned to the aeration tank 21 via the line L23, and the microorganism concentration in the aeration tank 21 is kept high.

  As described above, in the biological denitrification treatment apparatus 200, the methanol remaining in the treated water after the denitrification treatment by the reaction tank 6 is reliably removed by the hydrogen donor removal apparatus 20.

  Moreover, since the sedimentation tank 22 of the hydrogen donor removal apparatus 20 comprises a high-speed coagulation sedimentation tank, the installation area of the precipitation tank 22 can be made small. Moreover, since the flocs aggregated with microorganisms are returned to the aeration tank 21, the concentration of microorganisms in the aeration tank 21 increases. For this reason, the removal process of the methanol in the aeration tank 21 can be made into a high load, and the installation area of the aeration tank 21 can be made small. Therefore, the increase in the installation area accompanying attaching the hydrogen donor removal apparatus 20 can be suppressed small.

  In addition, in this embodiment, although the structure which has the aeration tank 21 and the precipitation tank 22 was shown as the hydrogen donor removal apparatus 20, it is not this limitation. For example, it is good also as a structure using a downward flow sponge cube hanging type | mold (Downflow Hanging Sponge: DHS) reactor.

  As described above, in the first and second embodiments, the biological wastewater treatment apparatus has been described as a biological denitrification treatment apparatus, but the present invention is not necessarily limited to the denitrification treatment and is within the scope not departing from the gist thereof. It can be applied to various other wastewater treatment.

  Further, the hydrogen donor is not limited to methanol, and for example, IPA (isopropyl alcohol), organic waste liquid such as acetic acid and molasses can be used.

  DESCRIPTION OF SYMBOLS 2 ... Conditioning apparatus, 3 ... Reaction apparatus, 4 ... Conditioning tank, 6 ... Reaction tank, 7 ... Aeration means, 9 ... Microbial sludge bed, 22 ... High-speed coagulation sedimentation tank, 100 ... Biological denitrification processing apparatus, L4 …line.

Claims (1)

In biological wastewater treatment equipment that treats wastewater using microbial sludge,
It has a sealed first tank, water to be treated as waste water is introduced into the first tank, a hydrogen donor is supplied to the water to be treated, and the water to be treated is discharged out of the first tank. A conditioning device to
A second tank sealed and containing a microbial sludge bed containing microorganisms aggregated in a granular form; the treated water discharged outside the first tank is introduced into the second tank; A reactor for raising treated water to form an upward flow in the second tank, and discharging the treated water as treated water to the outside of the second tank;
A return line for returning a part of the treated water discharged outside the second tank to the first tank;
A biological wastewater treatment apparatus , comprising: a diffuser for supplying an oxygen-containing gas to a lower portion in the second tank .

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