JP2005199167A - Oil-containing wastewater treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil-containing wastewater treatment method and apparatus which comprise a flow control tank (or a flow control process), an aerobic filter bed contact aerating biological treatment tank (or a biological treatment process), a settling tank (or a settling process), can peel off a biomembrane having an oil decomposability against animal and vegetable oil thickened on a carrier surface, and can concurrently purify the oil and BOD of animal and vegetable oil-containing wastewater in the aerobic filter bed contact aerating biological treatment tank (or the biological treatment process). <P>SOLUTION: The oil-containing wastewater treatment apparatus comprises the flow control tank, the aerobic filter bed contact aerating biological treatment tank, and the settling tank, can peel off the biomembrane having the oil-decomposability against the animal and vegetable oil thickened on the carrier surface, and can concurrently purify the oil and BOD of the animal and vegetable oil-containing wastewater in the biological treatment tank. Especially in the aerobic filter bed contact aerating biological treatment tank, carriers made of a porous urethane foam material are accommodated and packed in a carrier accommodation cage to retain oil-decomposing bacteria and aerobic bacteria in a high density. The oil and BOD are efficiently decomposed and purified into carbon dioxide gas and water. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil-containing wastewater treatment method and apparatus for treating oil-containing wastewater containing animal and vegetable oils and the like with aerobic microorganisms.

  Conventionally, about the processing apparatus and method of fat and oil containing wastewater and fat and oil containing kitchen wastewater of a food manufacturing factory, after aggregating fats and oils with a chemical beforehand and pre-treating with a pressure flotation device, a contact aeration method using a biofilm or The activated sludge method has been generally used, but there are many problems such as bad odor, large amount of chemicals used, large amount of sludge generated, high running cost, large installation space, etc. The wastewater is adjusted to pH in the previous stage, and oil-decomposing bacteria are added to the pH-adjusted wastewater, and it is composed of a plurality of stages of biological treatment processes (means). At least one of the biological treatment processes is a carrier. Filter bed process (means) fixed with aeration, aeration process (means) for biological treatment under aeration, and circulation / watering process (means) for sprinkling part of the treated water in the aeration process (means) to the filter bed process (means) ), Biological treatment A vegetable oil-containing drainage method comprising a precipitation step (means) for solid-liquid separation of wastewater treated in the step (means) and a return step (means) for returning the precipitate to a biological treatment step (means) is known (for example, , See Patent Document 1 and Patent Document 2).

In addition, an oil decomposition tank that decomposes oil in the oil-containing wastewater by the biological action of oil-degrading bacteria, a biological treatment tank that treats organic wastewater from the oil decomposition tank aerobic, and sludge and treatment after biological treatment Sludge separation means for solid-liquid separation of the mixed liquid with water, sludge circulation passage for circulating a part of the separated sludge to the biological treatment tank, sludge solubilization treatment tank for solubilizing the remaining separated sludge, and solubilization There is also an oil-containing wastewater treatment device provided with a solubilized sludge circulation channel for circulating the sludge to the biological treatment tank (for example, see Patent Document 3).
JP 2002-018441 A (page 2) JP 2002-018458 A (page 2) JP 2002-233890 A (page 3)

  As described above, various inventions for treating wastewater containing animal and vegetable oils with microorganisms have been proposed, but these technical backgrounds are based on microorganisms having oil-degradability of animal and vegetable oils contained in wastewater. It constitutes a biological treatment apparatus and method, and these points are certainly considered to have usefulness and specificity, respectively.

  However, in particular, there is no description in any of these background arts regarding peeling of biodegradable biofilms (sludge) of animal and vegetable oils thickened on the surface of the carrier, and oil decomposability of animal and vegetable oils thickened on the surface of the carrier. Unless the biofilm (sludge) having s is peeled off, it becomes difficult to hold the oil-decomposable microorganisms on the carrier, and the activation of the oil-decomposable microorganisms cannot be promoted.

  Therefore, in this sense, there are problems in terms of degradation effect, carrier retention, operation method, and the like regarding biological treatment with microorganisms having oil decomposability.

  This invention is made | formed in view of such a subject, The flow treatment tank (or flow adjustment process), the biological treatment tank (or biological treatment process) of aerobic filter bed contact aeration, the precipitation tank (or precipitation) A biological treatment tank (or biological treatment step) for aerobic filter bed contact aeration of wastewater containing animal and vegetable oils. Oil and BOD can be purified at the same time.

  Especially in a biological treatment tank (or biological treatment process) with aerobic filter bed contact aeration, a porous urethane foam carrier is stored and filled in a carrier storage cage, so that oil-degrading bacteria and aerobic bacteria are densely packed. It is possible to provide an oil-containing wastewater treatment method and apparatus for efficiently decomposing and purifying oil and BOD into carbon dioxide gas and water.

  Furthermore, the present invention preferably implements the oil-containing wastewater treatment method, has a simple tank / equipment (or process) configuration, has low initial and running costs for equipment, and can be treated in a short time. Methods and apparatus are provided.

The method for treating oil-containing wastewater according to the present invention is a method for treating the oil-containing wastewater comprising a flow rate adjustment step for making the oil-containing wastewater load uniform, an oil-decomposing bacteria charging step, a contact aeration step, and an aerobic filter bed step, The contact aeration step comprises a precipitation step in which excess aeration is maintained at an aeration intensity of 7 to 9 m ³ / m ³ · hr, and sludge generated from the aerobic filter step is solid-liquid separated. Is filled with a carrier made of a porous urethane foam and housed in a carrier housing cage to retain microorganisms at a high concentration and prevent clogging and outflow.

According to the present invention, the oil-containing waste water is subjected to excess aeration (aeration strength: 7 to ⁹ m ³ / m ³ · hour), so that in the aerobic filter bed process, the porous urethane foam material in the carrier storage cage can be used as a carrier. The supported oil-degrading bacteria create an environment where it is easy to actively work, and the oil-degrading bacteria can decompose the oil without performing oil-water separation.

  Further, by storing the carrier in the carrier storage cage, it is possible to prevent the porous urethane foam carrier from being blocked, outflowed, and worn.

  According to the first to fourth aspects of the present invention, the porous urethane foam material in the carrier storage cage in the aerobic filter bed device (or the aerobic filter bed process) is obtained by making the oil-containing waste water excessively aerated. The oil-degrading bacteria (Bacillus bacteria, Pseudomonas bacteria, etc.) carried on this carrier create an environment in which active activity is likely to occur, and oil (N-hexane) can be decomposed without oil-water separation by the oil-degrading bacteria.

  In addition, by breeding Bacillus which is one of the oil-degrading bacteria, the deodorizing effect peculiar to Bacillus is increased, and the rot can be effectively prevented by the synergistic effect of excess aeration and Bacillus.

  Furthermore, by storing the porous urethane foam carrier in the carrier housing cage, it is possible to prevent the porous urethane foam carrier from being blocked, outflowed, and worn.

  In addition, the carrier housing cages collide strongly with each other due to excessive aeration, and at the same time, the porous urethane foam carrier in the carrier housing cage (the volume ratio of the carrier in the carrier housing cage is 50 to 90%). By swinging, the biodegradable biofilms (such as dead oil-degrading bacteria) of animal and vegetable oils that thicken on the porous urethane foam carrier surface can be peeled off, and oil can be decomposed stably and reliably. .

  Hereinafter, an embodiment of the method and apparatus for treating oil-containing wastewater of the present invention will be described with reference to the drawings.

  FIG. 1 is a flow diagram showing an oil-containing wastewater treatment method and apparatus according to an embodiment of the present invention, and FIG. 2 is an external view of a carrier housing cage of the same example.

  In FIG. 1 (and FIG. 2), 1 indicates oil-containing wastewater (raw water) containing animal and vegetable oils taken into the raw water tank 2, and air is supplied from the diffuser pipe 8 at the bottom of the raw water tank 2 as necessary. Rotation (solidification) of the oil-containing wastewater 1 is prevented.

  This oil-containing wastewater 1 is a flow rate adjusting tank 3 (or a flow rate adjusting step) for adjusting the treatment flow rate of the oil-containing wastewater 1 in order to make the load of the oil-containing wastewater 1 of each processing device (or each processing step) uniform thereafter. 3a). In this flow rate adjustment tank 3 (or flow rate adjustment step 3a), pH adjustment (substantially neutral pH = 6 to 8) is performed as necessary, or air is supplied from the air diffuser 8. The flow of each of these (purification) processing apparatuses (or processing steps) is indicated by an arrow (→), and the same description will be given hereinafter.

  4 shows an oil-degrading bacteria charging device (or oil-degrading bacteria charging step 4a), and microorganisms such as Bacillus bacteria and Pseudomonas bacteria are charged and added to the oil-containing wastewater 1 as oil-degrading bacteria, and aerobic filtration for the next biological treatment It is sent to the floor apparatus 5 (or aerobic filter bed process 5a) and the contact aeration apparatus 9 (or contact aeration process 9a). Oil-degrading bacteria are introduced at the start of operation and are not normally added.

  In this aerobic filter bed device 5 (or aerobic filter bed step 5a), a carrier storage cage 7 in which a carrier 6 is stored and filled in advance (for example, in a spherical shape) is immersed. The carrier 6 is made of, for example, a porous urethane foam, and supports and holds oil-degrading bacteria at a high concentration and stability on the surface thereof. At the same time, the carrier storage cage 7 is divided and decomposed by the carrier 6. -It is prevented from being worn out and flowing out of the opening to the outside of the carrier housing cage 7 and from being blocked.

  That is, the porous urethane foam carrier 6 has a high specific surface area and can carry a large number of oil-decomposing bacteria / microorganisms on the surface thereof. On the surface of this porous urethane foam carrier 6, not only the oil-decomposing bacteria that are supported, but also various biota with nutrients from the metabolites and BOD (biochemical oxygen demand) components in the oil-containing wastewater 1 are present. Although formed, the BOD component and the like can be effectively removed simultaneously with the oil.

The contact aeration apparatus 9 (contact aeration process 9a) maintains the aerobic filter bed apparatus 5 (or the aerobic filter bed process 5a) in an excess aeration (aeration intensity of 7 to ⁹ m ³ / m ³ · hr) state. The excess aeration (air floating) first maintains the dissolved oxygen concentration (DO) / oxygen dissolution efficiency of the aerobic filter device 5 (or the aerobic filter step 5a) at a high level and maintains a high aerobic state. Therefore, the generation of bad odor is greatly improved. As will be described later, since the carrier housing cage 7 and the porous urethane foam material carrier 6 repeatedly oscillate and collide with each other, the oxygen absorption efficiency of the porous urethane foam material carrier 6 is enhanced, and It can be activated, stabilized and densified. Therefore, at the same time, the surface of the carrier housing cage 7 can be prevented from being blocked by oil.

  In this case, the specific gravity of the porous urethane foam material as the carrier 6 is 1.2 to 1.5 as a guide, and the porous urethane foam carrier 6 in the carrier housing cage 7 has a volume ratio of By setting the content to 50 to 90%, the porous urethane foam carrier 6 in the carrier housing cage 7 can be easily and vigorously swung, the biofilm can be peeled off, and the oil-degrading bacteria can be activated. Leads to.

  Here, the oil-degrading bacteria input device 4 (or oil-decomposing bacteria input step 4a), the aerobic filter bed device 5 (or aerobic filter bed step 5a), the contact aeration device 9 (or contact aeration step 9a). Collectively, the biological treatment tank 10 (or biological treatment step 10a) is used.

  Reference numeral 15 denotes a measuring means, which measures the pH of the aerobic filter bed device 5 (or the aerobic filter bed step 5a) and the process of change state such as BOD, and is subjected to a predetermined excess contact aeration and oil-containing drainage. 1 purification process is performed.

  When purification is completed by the measuring means 15 (measured value is confirmed) and there is no sludge, it is discharged to the outside as treated water (discharged water) 12 as it is by the switching means a (16a). However, when the purification is completed (measured value is confirmed) and there is a sludge, it is sent to the next sedimentation tank 11 (or precipitation process 11a) by the switching means a (16a), and the biological treatment tank 10 (or The sludge generated from the biological reaction in the biological treatment step 10a) is subjected to solid-liquid separation, and the liquid is discharged to the outside as treated water (discharged water) 12.

  The sludge is returned as return sludge 13 or surplus sludge 14 and is circulated and purified again. That is, according to the degree and state of the oil-impregnated drainage 1 dirt (oil-impregnated wastewater 1 load), either one of the return sludge 13 and the excess sludge 14 is selected by the switching means b (16b).

  1) When the dirt (excessive oil content, etc.) is large and it is more efficient to recirculate (purify) the treatment, for example, the excess sludge 14 is in the flow rate adjustment tank 3 (or the flow rate adjustment tank process 3a). Move back.

  2) There is little dirt (oil deficiency, etc.), and the aerobic filter bed device 5 (or aerobic filter bed step 5a), the contact aeration device 9 (or contact aeration step 9a), pH, BOD, etc. are excessively aerated. In order to prevent the oil-decomposing bacteria / microorganisms from dying due to this, the return sludge 13 minutes is immediately returned to the biological treatment tank 10 (or the biological treatment step 10a).

  Thus, by the measurement of the measurement means 15, the control means (detailed explanation by illustration etc. is omitted) determines whether the treated water 12 is discharged or the purification process (operation) is continued / terminated, for example, dissolved oxygen. The determination is made where there is no change in the density (by the way, the BOD value at this time is 200 to 300).

Aerobic filter bed apparatus 5 (or aerobic filter bed step 5a) Describing the aeration intensity in, the aeration intensity in normal waste water treatment facilities typically are the times 1~4m ³ / m ³ ·, if When the aeration intensity is increased to 8 m ³ / m ³ · h, the BOD (Biochemical Oxygen Demand) drops sharply, nitrification is promoted, the pH becomes acidic (pH 5 or less), and the bacteria (microorganism) activity is lost. .

However, in this embodiment, the excess aeration intensity is maintained at 7 to ⁹ m ³ / m ³ · hour (preferably 8 m ³ / m ³ · hour). The reason is that the oil-containing wastewater 1 has a dirty oil, so that the BOD is high even when the aeration intensity is 8 m ³ / m ³ · hr (the BOD drop is small) and the nitrification is not promoted.

That is, by performing excess aeration,
1) Each carrier storage cage 7 (and porous urethane foam carrier 6) swings, collides and rotates,
2) The oil-containing wastewater 1 and the oil-degrading bacteria are greatly stirred and flowed, and the aerobic filter bed device 5 (or the aerobic filter bed step 5a) is almost uniformly in a highly aerobic state.

  Accordingly, 1) each carrier storage cage 7 swings irregularly (disorderly) and collides (rotates) with the apparatus wall surface, and at the same time, the porous urethane foam carrier 6 in the carrier storage cage 7 Owing to rocking and collision, it becomes easy to carry oil-degrading bacteria.

  2) In the highly aerobic state, the oil-decomposing bacteria / microorganisms are activated by the rocking of the porous urethane foam carrier 6, and the oil-decomposing action of the oil-containing wastewater 1 is further promoted.

  3) By swinging / collision of the porous urethane foam carrier 6, the biofilm that thickens on the surface of the porous urethane foam carrier 6 can be efficiently peeled off to prevent the closure. In other words, the organism can be supported at a high concentration on the surface of the porous urethane foam carrier 6 simply by flowing the porous urethane foam carrier 6, but the porous urethane foam carrier is supported by flow and collision. If 6 wears out and becomes a small particle and the porous urethane foam carrier 6 outflow prevention screen or the like is clogged. However, as in the present embodiment, since it is oscillated and fluidized inside the carrier housing cage 7 by being housed in the carrier housing cage 7, the opening on the outer shell surface of the carrier housing cage 7 is large. Also prevents outflow and clogging.

  The effects of this embodiment are as follows: 1) An excellent biological treatment system that purifies the oil-containing wastewater 1 without separating oil and water (without dividing tanks, devices, and processes).

  2) Not only the treatment of the oil-containing wastewater 1, but also the prevention of malodor and the reduction of waste after treatment (excess sludge and dewatered cake) are possible.

  3) In the aerobic filter bed device 5 (aerobic filter bed step 5a), the porous urethane foam carrier 6 is filled in the carrier storage cage 7 so that oil-decomposing bacteria and aerobic bacteria are densely attached. It can be raw, retained and fixed, and can efficiently decompose, purify and remove oil and BOD into carbon dioxide and water.

  4) Simple operation (no need for pressurized levitation etc.) is easy to manage.

  5) It is not necessary to replenish chemicals or check the aggregation state.

  6) Separately, it is obvious that the purification treatment operation can be easily automated by adding the measuring means and the control means to the present embodiment.

  If the oil-containing wastewater treatment method and apparatus of the present invention is used in combination with the conventional general contaminated wastewater treatment method and apparatus, both wastewater purification treatments can be multi-functionalized and rationalized at the same time, and at a low price. It can be easily applied to purification treatment in a short time.

The flowchart which shows the processing method and apparatus of the oil containing waste_water | drain in one Example of this invention. External view of the carrier storage cage of the same example

Explanation of symbols

1 Oil-containing wastewater (raw water)
2 Raw water tank 3 Flow rate adjustment tank (or flow rate adjustment process 3a)
4 Oil-degrading bacteria input device (or oil-degrading bacteria input process 4a)
5 Aerobic filter bed device (or aerobic filter bed process 5a)
6 Carrier 7 Cage for Carrier Storage 8 Aeration Tube 9 Contact Aeration Device (or Contact Aeration Process 9a)
10 biological treatment tank (or biological treatment process 10a)
11 Precipitation tank (or precipitation step 11a)
12 Treated water (discharged water)
13 Return sludge 14 Surplus sludge 15 Measuring means 16a Switching means a
16b switching means b

Claims (4)

A method of treating the oil-containing wastewater comprising a flow rate adjusting step for making the oil-containing wastewater load uniform, an oil-degrading bacteria charging step, a contact aeration step, and an aerobic filter bed step, wherein the contact aeration step has an aeration intensity of It comprises a precipitation step for maintaining the excess aeration at 9 m ³ / m ³ · hr and separating the sludge generated from the aerobic filter bed into a solid and liquid, the aerobic filter bed step comprising a carrier made of porous urethane foam A method for treating oil-containing wastewater, wherein microorganisms are retained at a high concentration and are prevented from clogging and outflowing by being stored in a carrier storage cage. A treatment apparatus for treating oil-containing wastewater, comprising a flow rate adjusting tank for adjusting the treatment flow rate of the oil-containing wastewater, an oil-decomposing bacteria input device, a contact aeration device, and an aerobic filter bed device, and an aerobic filter bed device Characterized in that the aerobic filter bed is filled with a carrier made of porous urethane foam, and the carrier is housed in a carrier housing cage. Oil-containing wastewater treatment equipment. The method for treating oil-containing wastewater according to claim 1, wherein the carrier in the carrier housing cage has a volume ratio of 50 to 90%. 3. The oil-containing wastewater treatment apparatus according to claim 2, wherein the carrier in the carrier housing cage has a volume ratio of 50 to 90%.

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