JP6151578B2 - Wastewater treatment equipment - Google Patents

Description

  The present invention relates to a wastewater treatment apparatus that treats organic wastewater using activated sludge supported on a carrier.

  As a sewage treatment apparatus, one using activated sludge has been conventionally known. Specifically, this type of apparatus includes an aeration tank that aerates sludge to perform activated sludge treatment, and a filtration membrane apparatus that is provided in the aeration tank and separates the activated sludge mixed liquid in the tank by solid-liquid separation by filtration. A suction pump connected to the filtration membrane device for sucking the filtrate from the same member and flowing it out, and a suction pump connected to the filtration membrane device and provided in a suction path connecting the filtration membrane device and the suction pump. And a pressure gauge for measuring the suction negative pressure.

  In addition, in order to increase the efficiency of wastewater treatment with activated sludge, a technique is known in which a carrier such as activated carbon is added to the wastewater stored in the treatment tank and various organic substances and bacteria are carried on this carrier (the following patent document). 1, Patent Document 2, Patent Document 3).

  In Patent Document 1, by adding a powdered carbon-based adsorbent to the wastewater, in addition to sewage treatment by biological treatment, deodorization treatment of the wastewater and the like are also possible.

  In Patent Document 2, granular activated carbon is added to the waste water inside the treatment tank, and aerobic microorganisms are adsorbed on the surface of the activated carbon, thereby biologically treating the waste water.

  In Patent Document 3, chromaticity and COD are decomposed by adding powdered activated carbon to wastewater during biological treatment using activated sludge.

Japanese Patent No. 3142792 JP 2000-197895 A JP 2002-192184 A

  However, in the invention described in the above-mentioned patent document, a resin filtration membrane made of a resin material such as polyolefin is adopted as the filtration membrane. When a hard material having a large specific gravity is adopted as the carrier, the carrier is a filtration membrane. There was a risk that the membrane would be destroyed by contact with the filter.

  Moreover, when performing a filtration process in the processing tank which performs an activated sludge process, if powdered activated carbon is used as a support | carrier, it will become filtration resistance because this activated carbon accumulates on a filtration membrane. Furthermore, if the activated carbon is too small, it is discarded together with the sludge, and it is necessary to replenish the carrier after that, which is not economical.

  On the other hand, although it is considered to use a large carrier made of activated carbon having a width of several millimeters, there is a risk that the resin filtration membrane may be destroyed by the impact of the carrier as described above. Furthermore, the carrier may be sandwiched between the filtration membranes, or the carrier may come into contact with the wall surface of the treatment tank and be crushed, and the treatment of the crushed carrier may be complicated.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a wastewater treatment apparatus in which treatment efficiency is improved by using a carrier.

The wastewater treatment apparatus of the present invention includes a treatment tank in which wastewater containing activated sludge is stored, a hard filtration membrane immersed in the wastewater, and a gas that generates gas below the hard filtration membrane inside the wastewater. A hard carrier made of a hard material having a specific gravity greater than that of water is added to the waste water stored in the treatment tank, and moves through the waste water while being filtered by the hard filtration membrane. The activated sludge is carried on the hard carrier, and a sludge layer comprising the hard carrier carrying the activated sludge is formed on the filtration surface of the hard filtration membrane, and the hard carrier carries the activated sludge. It is dispersed in the waste water in the state, and characterized that you form the sludge layer.

  In the present invention, a small hard material having a specific gravity larger than that of water is used as a material for a carrier supporting microorganisms contained in activated sludge. Therefore, a state in which the carrier is substantially uniformly dispersed in the wastewater is realized without the carrier floating on the upper surface of the wastewater, and the wastewater treatment efficiency is improved.

It is a figure which shows the waste water treatment apparatus of this invention, (A) is a perspective view which shows a waste water treatment apparatus generally, (B) is a conceptual diagram which shows the state by which activated sludge was carry | supported by the support | carrier. It is a figure which shows the waste water treatment apparatus of this invention, (A) is a perspective view which shows a filtration membrane, (B) is sectional drawing which shows a filtration surface. It is sectional drawing which shows the waste water treatment apparatus of this invention concretely.

  With reference to FIG. 1, the structure of the waste water treatment apparatus 10 which concerns on this form is demonstrated.

  The waste water treatment apparatus 10 of the present invention includes a treatment tank 12 in which waste water 24 is stored, a filtration membrane 16 immersed in the waste water 24, and an air diffuser 28 that is disposed below the treatment tank 12 and generates air 30. The filter 18 is mainly provided with a pump 18 that communicates via a pipe and applies a suction pressure. In FIG. 1, the pipes connecting the elements are indicated by thick solid lines.

  The function of the wastewater treatment apparatus 10 of this embodiment is to reduce the organic substances contained in the wastewater 24 by the activated sludge contained in the treatment tank 12, and further take out the filtered water 26 filtered by the filtration membrane 16 to the outside. There is. Therefore, the filtered water 26 after being treated by the wastewater treatment apparatus 10 of the present embodiment contains less organic substances and contains almost no organic solids compared to the wastewater 24 to be introduced. State. Furthermore, in this embodiment, a carrier is added to the wastewater stored in the treatment tank 12, whereby the microorganisms contained in the activated sludge 32 are maintained at a high concentration and the treatment efficiency is increased.

  The wastewater 24 to be treated in this embodiment is one in which an organic substance is contained in water at a high concentration. Specifically, the wastewater 24 is wastewater discharged from general sewage including manure and the like, a food factory, and the like.

  The processing tank 12 is a metal or resin container made of stainless steel or the like, and has a role of storing the drainage 24 to be filtered, the filtration membrane 16 and the like. Sludge treatment and filtration treatment of the drainage 24 are performed in the treatment tank 12.

  Here, the filtration membrane 16 is a flat membrane, and is immersed in the waste water 24 stored in the processing tank 12. Here, the filtration membrane 16 is in a state in which the filtration surface for substantial filtration is entirely immersed in the drainage 24. The internal space of the filtration membrane 16 communicates with the pump 18 via a pipe, and the drainage 24 is filtered by the filtration membrane 16 when the pump 18 applies a predetermined suction pressure to the internal space of the filtration membrane 16. . Thereby, the filtered water which is the filtered waste water 24 is taken out from the processing tank 12.

  As a material of the filtration membrane 16, a resin material, ceramic, sintered metal, a metal plate provided with fine filtration holes, or the like is employed. In FIG. 1A, only one filtration membrane 16 is immersed in the drainage 24, but actually, a plurality of filtration membranes 16 spaced at a predetermined interval are immersed in the drainage 24.

  The air diffuser 28 is disposed below the filtration membrane 16 inside the processing tank 12 and has a role of generating air 30. The specific shape of the air diffuser 28 is a tube-like shape having a hole at the top. The role of the air diffuser 28 is to generate air 30 inside the drainage 24, thereby supplying oxygen to the drainage 24 and causing the carrier added to the drainage 24 to flow.

  Here, a negative pressure is applied from the pump 18 to the filtration membrane 16 so that the pressure measured by the pressure gauge 20 is constant. As a result, the filtered water 26 in which the drainage 24 is filtered by the filtration membrane 16 passes through the pipe. It is taken out via. The suction pressure applied from the pump 18 to the internal space of the filtration membrane 16 is, for example, about 10 kPa.

  With reference to FIG. 1 (B), in this embodiment, the carrier 23 is added to the wastewater 24 in order to improve the efficiency of biologically treating the wastewater 24 stored in the treatment tank 12 with activated sludge. Here, the carrier 23 is a particle for supporting useful microorganisms contained in the activated sludge 32. As shown in this figure, the microorganisms constituting the activated sludge 32 are carried on the surface of the carrier 23, so that a large amount of the activated sludge 32 remains inside the treatment tank 12 and the treatment efficiency is increased.

  In this embodiment, a material having a specific gravity greater than that of water (that is, a specific gravity greater than 1) is used as the carrier 23. Thereby, the reduction | decrease of the purification function by the support | carrier 23 which carry | supported activated sludge 32 floating on the liquid level of the waste_water | drain 24 is suppressed. That is, by using the carrier 23 having a large specific gravity, the carrier 23 carrying the activated sludge 32 can be dispersed in the drainage 24.

  As the material of the carrier 23, an inorganic material having a certain hardness or more is employed. If, for example, a soft resin material is used as the material of the carrier 23, microorganisms enter from the cracks generated in the resin material, and the carrier expanded by the gas generated by the microorganisms floats to the liquid surface. Occur. Since the carrier 23 of this embodiment is made of a hard material having high hardness, it is difficult for the carrier 23 to crack. Further, even if a crack is generated in the carrier 23 and a microorganism enters the crack, the carrier 23 does not expand due to the generated gas, so that the carrier 23 is prevented from being lifted by this expansion. As a specific material of the carrier 23, activated carbon, foamed glass, zeolite, silica or the like can be employed.

  Furthermore, in this embodiment, by using the carrier 23 made of a hard material, an effect of suppressing the clogging of the filtration membrane 16 can be obtained. Specifically, since the filtration membrane 16 employed in this embodiment has extremely fine filtration holes, fine particles and activated sludge contained in the drainage 24 may be clogged in the filtration holes and the obtained flux may be reduced. There is. At this time, in this embodiment, the air 30 is diffused from the air diffuser 28 below the filtration membrane 16 inside the drainage 24, thereby raising the air 30 inside the drainage 24. As a result, a water flow from the lower side to the upper side is generated inside the drainage 24, and the carrier 23 also moves from the lower side to the upper side along this flow. Along with this movement, the carrier 23 having a high hardness comes into contact with the filtration surface of the filtration membrane 16, and the particles adhering to the filtration surface are separated to block the filtration holes.

  The size of the carrier 23 is a range in which the inside of the drainage 24 can float even when the specific gravity is larger than that of water. Specifically, the width of the carrier 23 is preferably 0.1 μm or more and 0.5 μm or less. By setting the width of the carrier 23 within this range, the carrier 23 behaves like a colloid, and the carrier 23 can be electrochemically dispersed inside the drainage 24. On the other hand, if the width of the carrier 23 is smaller than this range, the carrier 23 is too small compared to the microorganisms constituting the activated sludge, and the function of supporting the microorganisms is not exhibited. Moreover, if the width | variety of the support | carrier 23 becomes larger than this range, the support | carrier 23 with which the activated sludge 32 adhered will settle near the bottom face of the processing tank 12, and there exists a possibility that the process efficiency of an activated sludge may fall.

  The shape of the carrier 23 is not particularly limited, but a spherical shape, a hexahedron, or a shape approximating these shapes is adopted. Voids may or may not exist inside the carrier 23.

  Referring to FIG. 2A, when a flat membrane-like ceramic filtration membrane is employed as the filtration membrane 16, the main surface facing in the left-right direction on the paper surface is the filtration surface 16A. Filtration holes are formed in the entire filtration surface 16A. In addition, a large number of voids 16B (internal spaces) that are elongated in the vertical direction and extend in a rectangular parallelepiped shape are formed inside the filtration membrane 16. These void portions 16B communicate with a pipe connected to the vicinity of the upper end portion of the filtration membrane 16. And the filtration hole formed in 16 A of filtration surfaces is connected with the space | gap part 16B. Therefore, at the time of filtration, filtered water, which is treated water that has passed through the filtration surface 16A, is supplied to the pipe via the gap 16B.

  As described above, the filtration membrane 16 is made of a hard material such as ceramic. Therefore, even if the carrier stirred by the above-described aeration process contacts the filtration surface 16A, the filtration surface 16A is not damaged by the contact of the carrier 23.

  FIG. 2B is an enlarged cross-sectional view illustrating a portion surrounded by a dotted circle in FIG. 2A with reference to FIG. As shown in this figure, a sludge layer 22 composed of a carrier 23 carrying activated sludge may be formed on the surface of the filtration surface 16A. In this case, in order to prevent clogging of the filtration surface 16A, backwashing is required in which filtered water is injected into the filtration membrane 16 and the sludge layer 22 is separated from the filtration surface 16A. Here, the size of the filtration hole 16 </ b> C provided in the filtration surface 16 </ b> A is smaller than that of the carrier 23. Therefore, the possibility that the filtration hole 16C is blocked by the filtration hole 16C is small.

  With reference to FIG. 3, the waste water treatment apparatus 10 is further explained in full detail. Here, a plurality of filtration membranes 16D, 16E, and 16F are disposed on the waste water 24 stored in the processing tank 12 so that the filtration surfaces thereof face each other. By providing a plurality of filtration membranes, a large flux as the entire apparatus is secured.

  In this embodiment, air 30 is generated in the drainage 24 from the air diffuser holes 17 </ b> A provided in the air diffuser 28, but the air diffuser holes 17 </ b> A are arranged at locations suitable for stirring the carrier 23.

  Specifically, a diffuser hole 17 </ b> A is provided so that the air 30 enters the gap between the filtration membrane 16 </ b> D disposed on the leftmost side of the paper and the side wall of the processing tank 12. That is, the air diffuser hole 17A of the air diffuser 28 is disposed below the gap. As a result, the air 30 rises between the filtration membrane 16D and the side wall of the processing tank, whereby the carrier 23 also moves upward together with the water flow of the drainage 24 facing upward. Therefore, the effect that the carrier 23 is stirred inside the drainage 24 is obtained.

  Similarly, air diffusion holes 17B and 17C are provided below the gaps between the filtration membranes 16D, 16E and 16F. Further, a diffuser hole 17 </ b> D is disposed below the gap between the filtration membrane 16 </ b> F disposed at the right end and the side wall of the processing tank 12.

  With reference to each figure mentioned above, the method to purify waste water using the above-mentioned waste water treatment apparatus 10 is demonstrated.

  First, referring to FIG. 1A, waste water 24 is introduced into the processing tank 12 from the outside. The wastewater to be purified in this embodiment is one in which organic objects to be removed such as sewage are contained in water. Sewage itself may be introduced into the treatment tank 12, but sewage from which large solids have been removed by precipitation or the like may be introduced into the treatment tank 12. The treatment tank 12 is provided with a filtration membrane 16 for filtering sewage, and the filtration membrane 16 is entirely immersed in the drainage 24.

  Thereafter, the carrier 23 is introduced into the drainage 24 to generate air 30 from the diffuser 28. The amount of air 30 generated may be about the same as that of a normal membrane separation activated sludge method. Thereby, when the air 30 rises, the waste water 24, the activated sludge contained therein, and the carrier 23 are stirred inside the processing tank 12. Further, when the air 30 is diffused into the drainage 24, oxygen is supplied to the drainage 24 and the activity of the activated sludge 32 becomes active. Thereby, the activated sludge 32 is carried on the surface of the carrier 23, the activated sludge is concentrated, and the processing efficiency is improved.

  As described above, since the carrier 23 of this embodiment is composed of fine particles having a specific gravity greater than 1, the carrier 23 does not float on the liquid surface of the drainage 24, and the carrier 23 is well stirred as the drainage 24 flows. The

  In this embodiment, as described above, a hard material such as activated carbon is used as the material of the carrier 23. However, since a hard ceramic is also used as the filtration membrane 16, the filtration membrane is brought into contact with the carrier 23. 16 is prevented from being damaged.

  When the activated sludge 32 is sufficiently supported on the carrier 23 as described above, the filtered water 26 filtered by the filtration membrane 16 is taken out of the system by applying a negative pressure to the internal space of the filtration membrane 16 by the pump 18. The negative pressure applied by the pump 18 is controlled by the pressure gauge 20 so as to be within a predetermined range. The filtered water taken out is then discharged to the outside through a precipitation process, a disinfection process, and the like.

DESCRIPTION OF SYMBOLS 10 Waste water treatment apparatus 12 Processing tank 14 Pump 16 Filtration membrane 16A Filtration surface 16B Cavity 16C Filtration hole 16D, 16E, 16F Filtration membrane 17, 17A, 17B, 17C, 17D Air diffusion hole 18 Pump 20 Pressure gauge 22 Sludge layer 23 Carrier 24 Wastewater 26 Filtered water 28 Aeration unit 30 Air 32 Activated sludge

Claims (5)

A treatment tank in which wastewater containing activated sludge is stored;
A hard filtration membrane immersed in the waste water;
Gas generating means for generating gas under the hard filtration membrane inside the drainage, and
A hard carrier made of a hard material having a specific gravity greater than that of water is added to the waste water stored in the treatment tank, and the hard carrier moving in the waste water while being filtered by the hard filtration membrane, Activated sludge is supported,
A sludge layer made of the hard carrier carrying the activated sludge is formed on the filtration surface of the hard filtration membrane,
The hard carrier is dispersed in the waste water while supporting the activated sludge, and waste water treatment apparatus which is characterized that you form the sludge layer.   The waste water treatment apparatus according to claim 1, wherein the hard filtration membrane is made of ceramic.   The waste water treatment apparatus according to claim 1, wherein the hard carrier is made of an inorganic material.   The waste water treatment apparatus according to any one of claims 1 to 3, wherein the hard carrier is made of activated carbon, zeolite, silica, or foamed glass. The waste water treatment apparatus according to any one of claims 1 to 4, wherein the width of the hard carrier is 0.1 µm or more and 0.5 µm or less.

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