JP4337553B2 - Oil-containing wastewater treatment method and apparatus - Google Patents

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 fat and oil with a chemical beforehand and pre-treating with a pressure levitation 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. It is composed of multiple stages of biological treatment processes (means) in which the pH of the wastewater is adjusted in the previous stage, and oil-degrading bacteria are added to the pH-adjusted wastewater and treated under aerobic conditions. 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).
JP2002-018481 (2nd page) JP2002-018458 (2nd page) JP 2002-233890 (3rd page)

  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 that thicken 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, From a flow adjustment tank (or flow adjustment process), a biological treatment tank (or biological treatment process) of contact aeration, and a precipitation tank (or precipitation process) It is configured and can peel the biofilm that has oil-degradability of animal and vegetable oils that thicken on the surface of the carrier, and the oil and BOD components are simultaneously removed from the wastewater containing animal and vegetable oils in the biological treatment tank (or biological treatment process) of contact aeration. It can be purified.

  In particular, in a biological treatment tank (or biological treatment process) for contact aeration, by storing and filling a porous urethane foam carrier in a carrier housing cage, oil-decomposing bacteria and aerobic bacteria can be held at a high density. The present invention provides an oil-containing wastewater treatment method and apparatus for efficiently decomposing and purifying oil and BOD into carbon dioxide 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 adjusting step for making the oil-containing wastewater load uniform, an oil-decomposing bacteria charging step, a contact aeration step , and a precipitation step , wherein the contact aeration aerator aeration intensity in step (air per hour per aerator 1 m ³⁾ maintaining the excess aeration during 7~9m ³ / m ³ ·, solid sludge resulting from the contact aeration process in the precipitation step The aerobic step of separating the liquid and holding the microorganisms at a high concentration by storing and filling a carrier having a specific gravity of 1.2 to 1.5 made of a porous urethane foam in a plurality of carrier housing cages. By performing excess aeration of the filter bed device with the aeration device , the carrier housing cage is rocked, collided, and rotated, thereby preventing the carrier from being blocked or outflowed.

According to the present invention, the oil-containing waste water is excessively aerated (aeration intensity: 7 to ⁹ m ³ / m ³ · hour), so that it is supported on the carrier of the porous urethane foam in the carrier housing cage in the contact aeration process. An oil-degrading bacterium creates an environment where it is easy to actively work, and the oil-decomposing bacterium can decompose oil without 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 carrier of the porous urethane foam material in the carrier storage cage in the aerobic filter bed device (or the contact aeration process) is obtained by making the oil-containing waste water excessively aerated. The oil-degrading bacteria (Bacillus bacteria, Pseudomonas bacteria, etc.) carried on the surface 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 flowchart 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 or the like 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 is performed for the next biological treatment. It is sent to the floor device 5 (or contact aeration step 9a) and the aeration device 9 (or contact aeration step 9a). Oil-degrading bacteria are introduced at the start of operation and are not normally added.

In this aerobic filter bed device 5 (or contact aeration step 9a ), 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 the carrier 6 of this porous urethane foam, there are not only the oil-degrading bacteria that are supported, but also various biota that use the metabolites and the BOD (biochemical oxygen demand) component in the oil-containing wastewater 1 as nutrients. Although formed, the BOD component and the like can be effectively removed simultaneously with the oil.

Aerator 9 (contact aeration step 9a) is aerobic filter bed apparatus 5 (or, the contact aeration process 9a) to maintain the excess aeration (aeration intensity 7~9m ³ / m ³ o'clock ·) state. The excess aeration (air floating) first maintains the high dissolved oxygen concentration (DO) and oxygen dissolution efficiency of the aerobic filter bed device 5 (or contact aeration step 9a), and maintains a high aerobic state. Qi generation 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 contact aeration step 9a), and the aeration device 9 (or contact aeration step 9a) are collectively referred to. The biological treatment tank 10 (or biological treatment step 10a) is used.

In addition, 15 shows a measuring means, measures the process of the aerobic filter bed apparatus 5 (or contact aeration process 9a ), such as pH and BOD, and the process of change state, a predetermined excess contact aeration is made, and the oil-containing wastewater 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, 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 (e.g. oil shortage), and the pH and BOD of the aerobic filter bed device 5 (or contact aeration step 9a) and aeration device 9 (or contact aeration step 9a) are decomposed by excess aeration. In order to prevent the situation where the bacteria and microorganisms are killed, the returned sludge 13 minutes is immediately returned before 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).

The aeration strength in the aerobic filter bed device 5 (or the contact aeration step 9a) (the amount of air per hour per 1 m ³ of the aeration device) will be described. The aeration strength in a normal wastewater treatment facility is generally 1 to 4 m ^3. / m ³ are the times-and if the aeration intensity 8m ³ / m ³ · during raising BOD (biochemical oxygen demand) is lowered rapidly, and nitrification is promoted, pH is acidic (pH 5 or less) The activity of bacteria (microorganisms) 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-decomposing bacteria are greatly stirred and fluidized, and the aerobic filter bed device 5 (or the contact aeration step 9a ) is almost uniformly in a highly aerobic state.

  Therefore, 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 swinging of the porous urethane foam carrier 6, and the oil decomposing action of the oil-containing wastewater 1 is further promoted.

3) The biofilm that thickens on the surface of the porous urethane foam carrier 6 is efficiently peeled off by the swinging / collision of the carrier 6 made of porous urethane foam and having a specific gravity of 1.2 to 1.5 , and then closed. Can be prevented in advance. 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, since the carrier 6 having a specific gravity of 1.2 to 1.5 is housed in the carrier housing cage 7 as in this embodiment, the carrier 6 is rocked and fluidized inside the carrier housing cage 7. Outflow and clogging can be prevented even if the outer shell surface of the cage 7 is large.

  The effects of this embodiment are as follows: 1) An excellent biological treatment system that purifies the oil-containing wastewater 1 without performing oil-water separation (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 (or contact aeration step 9a ), 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 measurement means and 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

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 charging device (or oil-degrading bacteria charging process 4a)
5 Aerobic filter device (or contact aeration process 9a)
6 Carrier 7 Carrier storage cage 8 Air diffuser tube 9 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 Excess 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 load of oil-containing wastewater uniform, an oil-degrading bacterium feeding step, a contact aeration step , and a precipitation step , wherein the aeration device has an aeration intensity (aeration device) Maintaining an excess aeration of 7-9 m ³ / m ³ · h per 1 m ³ of air), and sludge generated from the contact aeration step is solid-liquid separated in the precipitation step ,
In the contact aeration step, an aerobic filter bed apparatus that retains microorganisms at a high concentration by storing and filling a carrier having a specific gravity of 1.2 to 1.5 made of a porous urethane foam in a plurality of carrier storage cages. An oil-containing wastewater treatment method characterized in that the carrier aeration cage is rocked, collided, and rotated by performing excess aeration with the aeration apparatus , thereby preventing the carrier from being blocked or outflowed. A treatment apparatus for treating oil-containing wastewater, a flow rate adjusting tank for adjusting the treatment flow rate of the oil-containing wastewater, a biological treatment tank for biologically treating the oil-containing wastewater whose flow rate has been adjusted, and oil decomposition constituting the biological treatment tank It consists of a fungus charging device, an aeration device, an aerobic filter bed device, and a sedimentation tank for solid-liquid separation of sludge generated from this aerobic filter bed device, and the aerobic filter bed device has a specific gravity made of porous urethane foam. It comprises a carrier of 1.2 to 1.5 and a plurality of carrier housing cages that contain and fill the carrier, and the aeration device has an aeration intensity (air amount per hour per 1 m ³ of aeration device) of 7 to An oil-containing wastewater treatment apparatus that maintains excess aeration at 9 m ³ / m ³ · hr and swings, collides, and turns the carrier housing cage. 2. The method for treating oil-containing wastewater according to claim 1, wherein the apparent volume of the carrier in the carrier housing cage is 50 to 90% of the volume of the carrier housing cage. . 3. The apparatus for treating oil-containing wastewater according to claim 2, wherein the apparent volume of the carrier in the carrier housing cage is 50 to 90% of the volume of the carrier housing cage. .

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