JP2010131566A - Method and apparatus for treating wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently decompose oils and fats and also to reduce excess sludge while achieving a low cost. <P>SOLUTION: While a soluble organic substance in oils and fats-containing wastewater is treated by BOD decomposing bacteria to the oils and fats-containing wastewater, for example, which are proliferated according to biological treatment in a bioreactor 1, to generate sludge, the sludge which contains these BOD decomposing bacteria and oils and fats decomposing bacteria is concentrated by a sludge concentration device 5 to provide the concentrated sludge, and this concentrated sludge is heated by a heating device 6. Then, while the heating temperature is set to a temperature at which many BOD decomposing bacteria are sterilized and many oils and fats decomposing bacteria are not sterilized, thereby sterilizing the BOD decomposing bacteria and suppressing decomposition of the soluble organic substance to reduce the excess sludge, many oils and fats decomposing bacteria are not sterilized to allow decomposition of the oils and fats by the oils and fats decomposing bacteria, and the concentrated sludge is heated like this. Thus, a running cost for carrying out heating is reduced compared with the case in which sludge that is not concentrated is heated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method and a wastewater treatment apparatus.

  Wastewater discharged from food factories contains a lot of soluble organic matter, so when treating this wastewater, the methane fermentation method that can recover soluble organic matter as methane gas and generates less excess sludge is often used. . Here, the wastewater of food factories that handle fats and oils in the manufacturing process contains a lot of fats and oils in addition to soluble organic substances, so that the fats and oils adhere to the granules formed by methane bacteria and float up. There's a problem.

  Therefore, in the past, pressurized flotation treatment was performed as a pretreatment for methane fermentation, and after removing oils and fats, processing was carried out by methane fermentation. During this pressurized flotation treatment, froth containing a large amount of fats and oils was generated. To do. This floss has a problem that it is poor in dehydration, is susceptible to spoilage, and generates a foul odor, and a treatment that does not generate floss is desired.

On the other hand, Patent Document 1 below describes a method for treating organic waste containing a large amount of oil at a temperature of 60 ° C. or higher using a thermophilic oil-degrading bacterium (Bacillus stearothermophilus) species. If this technique is applied to wastewater containing a large amount of the above fats and oils, generation of floss is eliminated, but the wastewater temperature must be maintained at a temperature of 60 ° C or higher.
JP 2002-10777 A

  Here, it is necessary to supply oxygen in order to decompose the fats and oils in the waste water with bacteria, and therefore it is necessary to aerate the biological reaction tank in which the oil-degrading bacteria are accommodated with air or the like to supply oxygen.

  However, since the temperature decreases when aeration is performed, the temperature must be constantly maintained at 60 ° C. or higher by heating, and thus there is a problem that the running cost for performing the heating increases.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus capable of sufficiently decomposing oil and fat while reducing costs.

  Here, as a result of intensive studies, the present inventors have found the following mechanism. That is, when fat-containing wastewater containing fats and oils is biologically treated with fat-degrading bacteria, bacteria that decompose soluble organic matter (hereinafter referred to as BOD-degrading bacteria) grow at a fast rate, while the growth rate of fat-degrading bacteria is BOD. It has been found that it is slower than the decomposing bacteria, and therefore, the soluble organic matter is preferentially treated (decomposed) by the BOD degrading bacteria and inhibits the decomposition of the fats and oils by the oil degrading bacteria. As a result, it has also been found that a large amount of BOD-degrading bacteria are generated as excess sludge.

  Thus, the wastewater treatment method according to the present invention is a wastewater treatment method for biologically treating fat-containing wastewater containing fats and oils with fat-decomposing bacteria, concentrating sludge generated by biological treatment with fat-degrading bacteria, and heating the concentrated sludge. It is characterized by doing.

  Further, the wastewater treatment apparatus according to the present invention is a wastewater treatment apparatus for biologically treating fat-containing wastewater containing fats and oils with oil-degrading bacteria, a sludge concentration apparatus for concentrating sludge generated by biological treatment with fat-degrading bacteria, and this concentration And a heating device for heating sludge.

  Examples of the oil-degrading bacterium used herein include the genus Bacillus, the genus Psuedmonas, the genus Acinetobacter, and the like, but any microorganism that does not sterilize at 60 ° to 80 ° C. and decomposes fats and oils may be used.

  According to such a wastewater treatment method and wastewater treatment apparatus, the soluble organic matter in the fat-containing wastewater is treated by the BOD-degrading bacteria that grow in accordance with the biological treatment for the fat-containing wastewater, and sludge is produced. The sludge containing decomposing bacteria is concentrated into a concentrated sludge, and this concentrated sludge is heated. At this time, by setting the heating temperature to a temperature at which many of the BOD-degrading bacteria are sterilized and most of the oil-degrading bacteria are not sterilized, the BOD-degrading bacteria are partially sterilized and inactivated, and the soluble organic matter is decomposed. While being suppressed and reducing excess sludge, most of the oil-degrading bacteria are not sterilized, and the fats and oils can be decomposed by the oil-degrading bacteria. Moreover, since the concentrated sludge is heated in this way, the running cost for heating is reduced as compared with the case where the unconcentrated sludge (for example, the waste water in the entire tank) is heated. Therefore, the oil and fat can be sufficiently decomposed and the excess sludge can be reduced while reducing the cost.

  Here, the biological treatment by fat-and-oil decomposing bacteria for the fat-containing wastewater is aerobic biological treatment by aeration in the biological reaction tank, and sludge generated by this aerobic biological treatment is stopped in the biological reaction tank by stopping aeration. A processing step having a sedimentation concentration step for sedimentation in step, a supernatant discharge step for discharging the supernatant in the biological reaction tank, and a heating step for heating the sedimentation concentration sludge in the biological reaction tank after discharging the supernatant. It is preferable to carry out every period.

  According to this, in the sedimentation and concentration step, aeration in the biological reaction tank is stopped, so that sludge containing BOD-degrading bacteria and oil-degrading bacteria and aerobic biological treatment is settled and concentrated, and in the supernatant discharge step, The supernatant in the biological reaction tank is discharged, and in the warming process, the sedimented and concentrated sludge in the biological reaction tank after the supernatant is discharged is heated, so the unconcentrated sludge (for example, waste water in the entire tank) is heated. Compared with the case where it reduces, the running cost for heating is reduced, many BOD degrading bacteria are sterilized, or the proliferation capability is lost, and the excess sludge is reduced. In addition, since these treatment steps are carried out at regular intervals, that is, at normal times during regular intervals, the fat and oil-containing wastewater is introduced into the biological reaction vessel and used for aerobic biological treatment. The temperature of the waste water is about 25 to 40 ° C., the activity of the oil-degrading bacteria in the biological reaction tank is activated, and the fats and oils are sufficiently decomposed by the oil-degrading bacteria. And since the above-mentioned series of processing steps are carried out at regular intervals in this way, the growth of BOD-degrading bacteria that are once sterilized but try to grow as the operation continues is suppressed, and the reduction of excess sludge is ensured. In addition, the running cost for heating can be further reduced by performing the operation at regular intervals.

  Here, since oil-degrading bacteria generally have a weak cohesive property and it takes time to settle and concentrate, it is preferable to supply a polymer flocculant for sedimentation and concentration. According to this, the oil-degrading bacterium becomes aggregated sludge by the polymer flocculant, and can be easily settled in a short time.

  Moreover, it is preferable to heat at 60 degreeC-80 degreeC. By heating at a temperature in this range, many of the BOD-degrading bacteria can be sterilized without sterilizing many of the oil-degrading bacteria.

  Further, the heating is preferably performed by steam.

  As described above, according to the present invention, it is possible to provide a wastewater treatment method and a wastewater treatment apparatus capable of sufficiently decomposing oil and fat and reducing excess sludge while reducing costs.

  Hereinafter, preferred embodiments of a wastewater treatment method and a wastewater treatment apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a wastewater treatment apparatus to which a wastewater treatment method according to the first embodiment of the present invention is applied. The wastewater treatment apparatus of this embodiment is, for example, wastewater from a food factory or the like. Is for introducing fat and oil-containing wastewater containing a large amount of oil and fat and soluble organic matter, removing oil and fat from this, and subjecting it to subsequent methane fermentation.

  The wastewater treatment apparatus 100 introduces the oil-containing wastewater into the biological reaction tank 1, and in the biological reaction tank 1, the aeration apparatus 3 diffuses air from the blower 3a from the diffuser pipe 3b to the bottom of the tank and performs aeration. Thus, the fat-containing wastewater is aerobically biologically treated, the treated water from the biological reaction tank 1 is introduced into the sedimentation tank 2, and the sedimentation tank 2 is allowed to settle so that the sedimentation concentrated sludge and the separated liquid are used. The liquid is separated into the treated water which is the supernatant, and the treated water is drained to the subsequent stage, while the sedimentation sludge in the settling tank 2 is returned to the biological reaction tank 1 through the return line 4 by driving the pump 4a. This is a so-called biological wastewater treatment apparatus configured as described above.

  Here, particularly in the present embodiment, the biological reaction tank 1 accommodates oil-degrading bacteria in the tank. Here, the oil-degrading bacterium is an aerobic bacterium that can effectively decompose oil and fat, and heat-resistant bacteria or yeast having a small surface area per cell weight is used and sterilized up to about 80 ° C. The activity is activated at about 25 to 40 ° C., and the fats and oils are decomposed.

  Particularly in this embodiment, an apparatus for sterilizing a BOD-degrading bacterium to be propagated in accordance with a biological treatment with an oil-degrading bacterium in a biological reaction tank 1 that normally performs a biological treatment with an oleo-degrading bacterium. Specifically, a sludge concentrating device 5 for concentrating sludge generated by biological treatment and a heating device 6 for heating the concentrated sludge are attached.

  The sludge concentrating device 5 includes a pump 5a immersed in the tank 1, and a drain line 5b connected to the pump 5a for draining the tank water to the outside. The pump 5a stops the operation of the blower 3a of the aeration apparatus 3 and the introduction of oil-containing waste water at a predetermined time described later (stops the normal operation), and settles the sludge in the tank 1 to separate the supernatant and the solid-liquid separation. Then, the supernatant (water) in the tank is drained to the outside through the drainage line 5b, and concentrated sludge is obtained in the lower part of the tank. Here, the concentration of the concentrated sludge can be adjusted by adjusting the installation position of the pump 5a.

  In the heating device 6, steam is used here, and when driving of the pump 5a of the sludge concentrating device 5 is completed, steam is supplied from the steam generation source 6a to the concentrated sludge in the tank 1 through the steam supply line 6b. While heating, the temperature of the concentrated sludge is monitored by the temperature sensor 6c disposed at the bottom of the tank 1, and the temperature is maintained for 60 hours so that the BOD-degrading bacteria can be sterilized. The heating device 6 is not limited to steam as long as it can heat the concentrated sludge.

  And these sludge concentration apparatus 5 and the heating apparatus 6 are driven in the state which stopped the driving | running | working at the normal time (drive | driving of the blower 3a and introduction | transduction of fat and oil containing waste water) for every fixed period.

  In this embodiment, a polymer flocculant supply device 7 for promoting the sedimentation of sludge is attached to the biological reaction tank 1. The polymer flocculant supply device 7 supplies the polymer flocculant dissolved in the polymer flocculant dissolution tank 7a to the biological reaction tank 1 through the polymer flocculant supply line 7c by driving the pump 7b. The supply of the polymer flocculant to the biological reaction tank 1 by the pump 7a is performed immediately before stopping the blower 3a and stopping the aeration.

  The polymer flocculant supply line 7c is branched in the middle, and the branched line 7d supplies the polymer flocculant also to the sedimentation tank 2 to promote sedimentation of sludge.

  In the wastewater treatment apparatus 100 configured in this way, normally, in the biological reaction tank 1 into which the fat and oil-containing wastewater has been introduced, BOD-degrading bacteria grow by aerobic biological treatment by aeration of the aeration apparatus 3. Dissolved organic substances are decomposed by the BOD-degrading bacteria, and fats and oils are decomposed by the oil-degrading bacteria. The BOD-degrading bacteria are generated as excess sludge. By supplying the agent, the aggregated sludge is easily formed and the sedimentation of the sludge is promoted to obtain the concentrated sludge. The concentrated sludge is returned to the biological reaction tank 1 through the return line 4.

  Here, in the present embodiment, the normal operation is stopped at regular intervals, and the sterilization process of BOD-degrading bacteria is performed. Here, it is carried out about once every two days. Prior to the sterilization process of the BOD degrading bacteria, the polymer flocculant is supplied to the biological treatment tank 1 by the polymer flocculant supply device 7 in advance.

  And the following sedimentation concentration process, a supernatant discharge process, and a heating process are implemented in this order.

  Specifically, first, in the sedimentation and concentration step, the introduction of fat and oil-containing wastewater into the biological treatment tank 1 and the drive of the blower 3a of the aeration apparatus 3 are stopped and left in a stationary state. And sludge containing oil-degrading bacteria is allowed to settle, and the liquid is separated from the supernatant. Here, the standing time is about 1 hour.

  At the time of this standing, since the polymer flocculant is supplied to the biological treatment tank 1 in advance, the oil-degrading bacteria that generally have weak cohesiveness and take time to settle and concentrate become aggregated sludge for a short time. To settle.

  And if solid-liquid separation is achieved, the pump 5a of the sludge concentration apparatus 5 will be driven in the following supernatant discharge process. Thereby, the supernatant (water | moisture content) in a tank is drained, sludge remains in the tank lower part, and concentrated sludge is obtained. When concentrated sludge is obtained in this way, the drive of the pump 5a is stopped.

  Next, in the heating step, steam is supplied to the concentrated sludge in the tank 1 by the heating device 6. Thereby, the concentrated sludge is heated to 60 ° C.

  Here, the heating temperature of 60 ° C. is a temperature at which most of the BOD-degrading bacteria are sterilized and most of the oil-degrading bacteria are not sterilized, so that the BOD-degrading bacteria are sterilized and decomposition of soluble organic matter is suppressed. While excess sludge can be reduced, oil-degrading bacteria are difficult to sterilize. And here, after heating is hold | maintained for about 1 hour, the drive of the heating apparatus 6 is stopped.

  When such a series of sterilization processes for BOD-degrading bacteria are performed, the normal operation is resumed, a specified amount of oil-containing wastewater is introduced into the biological treatment tank 1, and the blower 3a of the aeration apparatus 3 is driven.

  Then, the waste water temperature in the biological treatment tank 1 is lowered to about 25 to 40 ° C., the activity of the oil-degrading bacteria in the biological reaction tank 1 is activated, and the fats and oils are sufficiently decomposed by the oil-degrading bacteria.

  Such a series of sterilization steps are performed at regular intervals. As a result, the growth of the BOD-degrading bacteria that have been sterilized once but are about to grow with the continuation of the operation is suppressed, and the excess sludge can be surely reduced.

  Thus, in this embodiment, while the soluble organic substance in fats and oils-containing wastewater is processed by the BOD-degrading bacteria that proliferate according to the biological treatment for the fats and oils-containing wastewater, sludge is produced, while the BOD-decomposing bacteria and fats and oils-degrading bacteria are included The sludge is concentrated to obtain concentrated sludge, and this concentrated sludge is heated to a temperature at which many of the BOD-degrading bacteria are sterilized and most of the oil-degrading bacteria are not sterilized, so that partial sterilization or inactivation of the BOD-degrading bacteria is achieved. While decomposition of soluble organic matter can be suppressed and excess sludge can be reduced, most of the oil-degrading bacteria are not sterilized, and it is possible to decompose fats and oils by the oil-degrading bacteria. In addition, since the concentrated sludge is heated in this manner, the running cost for heating is reduced to 1/2 to that when non-concentrated sludge (for example, the entire drainage in the tank 1) is heated. It is reduced to 1/3. Therefore, the oil and fat can be sufficiently decomposed and the excess sludge can be reduced while reducing the cost.

  In addition, in order to carry out the processing steps including the sedimentation concentration step, the supernatant discharge step, and the heating step described above while stopping normal operation at regular intervals, the oil-containing wastewater is introduced into the biological reaction tank 1 at normal times. The bacteria will bathe at about 25 to 40 ° C., the activity of the oil-degrading bacteria in the biological reaction tank 1 is activated, and the oil-degrading bacteria are sufficiently decomposed and sterilized once. As the operation continues, the growth of BOD-degrading bacteria that are proliferating is suppressed, so that the oxygen consumption is also suppressed, power and surplus sludge can be reliably reduced, and heating is carried out at regular intervals. The running cost can be further reduced.

  Further, since the polymer flocculant is supplied during sedimentation and concentration, the oil-degrading bacteria can be agglomerated sludge by the polymer flocculant and can be easily settled in a short time.

  In the present embodiment, the heating temperature is set to 60 ° C, but may be 60 ° C to 80 ° C. By heating at a temperature in this range, many of the BOD-degrading bacteria can be sterilized without sterilizing many of the oil-degrading bacteria.

  Moreover, it replaces with the sludge concentration apparatus 5 provided with the pump 5a and the drainage line 5b, the membrane separator immersed in the biological reaction tank 1 is used as a sludge concentration apparatus, and this BOD decomposition | disassembly is not normally used but using this membrane separator. When sterilizing bacteria, the sludge is concentrated by solid-liquid separation by the membrane separation device, and the concentrated sludge is left in the biological reaction tank 1, and the separated liquid is discharged out of the biological reaction tank 1. Even if it is heated by a heating device using steam or the like and such sludge concentration and concentrated sludge are heated at regular intervals, it is possible to obtain substantially the same effect as in the first embodiment. it can. In addition, in the case of solid-liquid separation by a membrane separation device as described above, it is not necessary to stand as in the case of precipitation separation.

  Incidentally, by sterilizing many of the BOD-degrading bacteria in this way, the BOD of the treated water drained from the sedimentation tank 2 to the subsequent stage becomes higher than before, but this is due to the methane fermentation in the subsequent methane fermentation tank. Because it is processed, there is no problem.

  FIG. 2 is a schematic configuration diagram showing a wastewater treatment apparatus to which the wastewater treatment method according to the second embodiment of the present invention is applied.

  The difference between the wastewater treatment apparatus 200 of this embodiment and the wastewater treatment apparatus 100 of the first embodiment is that it is a device for sterilizing the BOD-degrading bacteria attached to the biological reaction tank 1, specifically, the sludge concentration device 5. In addition, the heating device 6 is eliminated and the normal biological reaction tank 1 is used, and here, the sedimentation tank 2 is a sludge concentrator (the configuration and action are the same as those in the first embodiment), and the concentrated sludge in the sedimentation tank 2 is biologically reacted. The heating device 16 is provided in the return line 4 for returning to the tank 1.

  The heating device 16 can be selected from various types such as those using steam, heaters, and the like. In short, the concentrated sludge to be returned to the biological reaction tank 1 is heated to the same temperature as in the first embodiment. Anything that can be warmed is acceptable.

  In the second embodiment, instead of the polymer flocculant supply device 7, the polymer flocculant dissolved in the polymer flocculant dissolution tank 7a is driven via the polymer flocculant supply line 7e by driving the pump 7b. Thus, a polymer flocculant supply device 17 for supplying the treated water from the biological reaction tank 1 to the line for introducing the treated water into the precipitation tank 2 is used.

  In such a wastewater treatment apparatus 200, BOD-degrading bacteria grow in the biological reaction tank 1 by aeration by the aeration apparatus 3, and soluble organic substances are decomposed by the BOD-degrading bacteria. The BOD-degrading bacteria are generated as surplus sludge. In the sedimentation tank 2, the aggregated sludge is easily formed by the supply of the polymer flocculant by the polymer flocculant supply device 17, and the sedimentation of the sludge is promoted and concentrated. Sludge is obtained, and this concentrated sludge is returned to the biological reaction tank 1 via the return line 4.

  And when returning this concentrated sludge, since the said concentrated sludge is heated by 60 degreeC-80 degreeC by the heating apparatus 16, like 1st embodiment, it is running by heating only concentrated sludge. While reducing the cost, partial sterilization and inactivation of BOD-degrading bacteria are attempted to suppress the decomposition of soluble organic matter and to reduce excess sludge. On the other hand, most of the oil-degrading bacteria are not sterilized. Thus, it is possible to break down fats and oils by the fat-degrading bacteria.

  That is, when the heated concentrated sludge is returned to the biological treatment tank 1 into which the fat-containing wastewater is introduced, the oil-degrading bacteria bathe at about 25 to 40 ° C. The activity is activated and the fats and oils are sufficiently decomposed by the oil-degrading bacteria.

  In addition, in this 2nd Embodiment, although the warming by the heating apparatus 16 is always performed, you may make it perform it for every fixed period.

  As described above, the present invention has been specifically described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and instead of the precipitation tank 2, for example, a concentration device (solid-liquid separation) such as a membrane separation device. The apparatus may be used to return the concentrated sludge to the biological reaction tank 1.

  In the present invention, when fat-containing wastewater is biologically treated with fat-decomposing bacteria in the biological reaction tank 1, sludge generated by biological treatment with fat-degrading bacteria is concentrated by a sludge concentrating device, and the concentrated sludge is heated by a heating device. As long as the heating can be performed, the configuration is not limited to that of the above-described embodiment.

  For example, in the above-described embodiment, a heating process for sterilizing BOD-degrading bacteria is performed at regular intervals, but in advance, n-Hex (normal hexane extract) of fat-and-oil-containing wastewater and necessary addition are added. A relationship with the temperature processing interval may be obtained, and the interval for performing the heating processing may be determined from this. In addition, the quality of the treated water may be measured, and when the water quality falls below the reference value, the heating process may be performed. Furthermore, instead of the water quality of the treated water, the number of target oil-degrading bacteria is measured by real-time PCR, or the fatty acid (R-COOH), which is an oil-decomposing product, is measured by gas chromatography, etc. You may make it perform a heating process.

  Hereinafter, Example 1 and Comparative Example 1 will be described.

Example 1
The wastewater from the ham manufacturing plant was treated using a test apparatus having a configuration similar to that shown in FIG. The properties of the wastewater were BOD; 1200 mg / L, SS; 300 mg / L, n-Hex (normal hexane extract); 500 mg / L, and the temperature was room temperature. SS was mostly biodegradable organic matter. The daily processing amount was 100 L. The biological reaction tank was 100 L, and MLSS (sludge concentration in the tank) was 5000 mg / L. The latter precipitation tank was 10 cm in diameter and 50 cm in height. Since the flocculation property of the oil-degrading bacteria (yeast) was not very good, 2 mg / L of a polymer flocculant was added to promote precipitation separation. In the test, once every two days, 250 mL of the polymer flocculant solution (0.2%) was added to the biological reaction tank, and after 1 minute, the aeration was stopped and allowed to stand for 1 hour to settle and concentrate the sludge. After that, the supernatant was discharged. In addition, the sludge accumulated in the sedimentation tank was transferred to the biological reaction tank and concentrated by sedimentation, and the supernatant was discharged. The amount of sludge concentrated by sedimentation was about 30L. The sedimented and concentrated sludge was heated with steam to 60 ° C. and left as it was for 1 hour. After standing, wastewater was introduced into the biological reaction tank for continuous treatment. The test was conducted over a month.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that no heating treatment was performed.

  In both Example 1 and Comparative Example 1, the amount of excess sludge generated was measured as the accumulated weight of the sludge extracted so that the MLSS in the biological reaction tank was constant. Table 1 shows the measurement results of the surplus sludge generation amount and the BOD, SS, and n-Hex of the treated water which is the supernatant of the sedimentation tank.

  As shown in Table 1, it can be seen that excess sludge is significantly reduced in Example 1 as compared with Comparative Example 1.

It is a schematic block diagram which shows the waste water treatment apparatus to which the waste water treatment method which concerns on 1st Embodiment of this invention is applied. It is a schematic block diagram which shows the waste water treatment apparatus to which the waste water treatment method which concerns on 2nd Embodiment of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Biological reaction tank, 2 ... Sedimentation tank (sludge concentration apparatus), 3 ... Aeration apparatus, 3a ... Blower, 3b ... Aeration pipe, 5 ... Sludge concentration apparatus, 5a ... Pump, 5b ... Drain line, 6, 16 ... Addition Temperature apparatus, 6a ... Steam generation source, 6b ... Steam supply line, 7 ... Polymer flocculant supply apparatus, 7a ... Polymer flocculant dissolution tank, 7b ... Pump, 7c ... Polymer flocculant supply line, 100, 200 ... Wastewater treatment equipment.

Claims (6)

In the wastewater treatment method of biologically treating fat-containing wastewater containing fats and oils with oil-degrading bacteria
Concentrate sludge produced by biological treatment with oil-degrading bacteria,
A wastewater treatment method characterized by heating the concentrated sludge. The biological treatment by the oil-degrading bacteria for the oil-containing wastewater is an aerobic biological treatment by aeration in a biological reaction tank,
A sedimentation concentration step for sedimenting and concentrating sludge produced by this aerobic biological treatment in the biological reaction tank by stopping aeration;
A supernatant discharge step of discharging the supernatant in the biological reaction tank;
The wastewater treatment method according to claim 1, wherein a treatment step comprising: a heating step of heating the sedimentation sludge in the biological reaction tank after discharging the supernatant is performed at regular intervals.   3. The wastewater treatment method according to claim 2, wherein a polymer flocculant is supplied for concentration by sedimentation.   It heats at 60 degrees-80 degrees C, The waste water treatment method as described in any one of Claims 1-3 characterized by the above-mentioned.   It heats with steam, The wastewater treatment method as described in any one of Claims 1-4 characterized by the above-mentioned. In wastewater treatment equipment for biologically treating fat-containing wastewater containing fats and oils with fat-degrading bacteria,
A sludge concentrator for concentrating sludge produced by biological treatment with oil-degrading bacteria;
A wastewater treatment apparatus comprising a heating device for heating the concentrated sludge.

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