JPWO2016103949A1 - Method and apparatus for treating oil-containing wastewater - Google Patents

Abstract

Provided is a method and an apparatus for treating fat-containing wastewater that can stably concentrate fat and oil regardless of the properties of the fat-containing wastewater, and can increase the treatment efficiency of biological treatment on the concentrated concentrate. thing. A method for treating fat-containing wastewater, characterized in that an oil salt-containing wastewater 1 is charged with an iron salt 2 and subjected to a concentration-separation process for concentrating and separating oil-and-fat, and a biological treatment is applied to the concentrate obtained by the concentration-separation process It is. Thereby, the iron salt 2 thrown into the fat and oil containing waste water 1 acts as an inorganic flocculant, and can concentrate and isolate | separate fats and oils stably irrespective of the property of the fat and oil containing waste water 1. FIG. Moreover, the decomposition efficiency of the fats and oils in the concentrate 22 can be improved by performing biological treatment to the concentrate 22 containing the iron salt 2. Furthermore, this invention provides the processing apparatus 10 of fat and oil containing waste water.

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for treating fat-containing wastewater, and more particularly, to a method and apparatus for treating fat-containing wastewater that involves biological treatment.

  Wastewater such as food factory wastewater and domestic wastewater contains a lot of oil and fat, and when such wastewater is discharged into the sewer pipe, solidified oil and fat adheres to the sewer pipe and blockage of sewer pipes and oil balls. Various problems caused by the large amount of oil and fat in the wastewater, such as occurrence, are caused.

  Therefore, generally, wastewater such as domestic wastewater is subjected to biological treatment in a biological treatment facility, and organic matter containing oil and fat is decomposed. However, if the fat content in the wastewater is large, a certain amount of time is required for the decomposition of the fat and oil by the activated sludge. Therefore, if the time for biological treatment is insufficient, the fat and oil will remain in the treated water after the biological treatment. On the other hand, if the biological treatment takes time, the treatment efficiency is lowered.

  As a treatment method for such wastewater containing fats and oils, a technique described in Patent Document 1 is disclosed.

  Specifically, Patent Document 1 discloses that fat and oil-containing wastewater is separated into fat and oil and separated water, and biological treatment is performed on the separated water, and the fat and oil is separately decomposed aerobically using microorganisms. In addition, a method for treating oil-containing wastewater in which the microorganism-containing liquid obtained by this decomposition treatment is subjected to separated water or biological treatment is disclosed.

  According to the treatment method of Patent Document 1, since the separated water is separated from the oil-containing wastewater, the contact efficiency between the oil and fat in the decomposition treatment and the microorganisms that decompose the oil and fat is increased, and rapid oil and fat decomposition is expected. it can. Moreover, since the microorganism-containing liquid after the decomposition treatment is subjected to biological treatment, the decomposition of the oil and fat further proceeds, and treated water with less oil and fat remaining after the biological treatment can be provided by rapid treatment.

  In addition, it is thought that an organic flocculant and an inorganic flocculant are arbitrarily added to the fat and oil containing waste water for separation of the fat and oil from the fat and oil containing waste water.

  Non-Patent Document 1 discloses that the reaction of lipase that catalyzes the decomposition reaction of fats and oils is strongly inhibited by iron.

  On the other hand, Patent Document 2 discloses a biological treatment apparatus that supplies an iron salt in a biological treatment process. Specifically, Patent Literature 2 discloses an iron salt supply means for supplying iron salt to a first treatment tank in a biological treatment apparatus that performs biological treatment of oil-containing wastewater in two treatment tanks arranged in series. A biological treatment device is disclosed. According to this biological treatment apparatus, the fats and oils in waste water are decomposed | disassembled efficiently compared with the case where iron salt is not supplied to a 1st treatment tank.

JP-A-4-235799 JP2013-184093A

Mieko Iwai, Lipase, Basics and Applications, pp. 168-173 (Shoshobo)

  However, the fat and oil-containing wastewater has variations in its properties due to the operational status of the facility that discharges the wastewater and the presence of contaminants. According to the treatment method of Patent Document 1, the properties of the fat and oil-containing wastewater Depending on the case, the ratio of oils and fats that can be separated in the separation step is lowered. That is, depending on the properties of the oil-containing wastewater, the ratio of the oil and fat remaining in the separated water increases, resulting in problems such as prolonged biological treatment time and reduced biological treatment efficiency.

  Addition of various flocculants has been studied in order to reduce the proportion of fat and oil remaining in such separated water, but iron salts have been known to strongly inhibit lipase reaction, The use of iron salts as inorganic flocculants has not been tried for substances that are expected to react with lipases.

  Moreover, although patent document 2 discloses supplying an iron salt to a biological treatment tank, there is no description about using an iron salt as a flocculant for fats and oils.

  The present invention has been made in view of the above problems, and its purpose is to stably concentrate fats and oils regardless of the properties of the fat-containing wastewater, and to perform biological treatment on the concentrated concentrate. An object of the present invention is to provide a method and apparatus for treating oil-containing wastewater that can increase the treatment efficiency.

  The method for treating oil-containing wastewater according to claim 1 for achieving the above object is obtained by performing a concentration separation process in which an iron salt is added to the oil-containing wastewater to concentrate and separate the oil and fat, and the concentration separation process is performed. The concentrate is subjected to biological treatment.

  According to this structure, the iron salt thrown into the fat and oil containing waste water acts as an inorganic flocculant, and the fat and oil content can be stably concentrated and separated regardless of the properties of the fat and oil containing waste water. Moreover, the decomposition efficiency of the fats and oils in a concentrate can be improved by performing biological treatment to the concentrate containing an iron salt. Such an improvement in decomposition efficiency is conventionally considered that iron salt inhibits lipase activity. However, in biological treatment, lipase and / or oil synthesis reaction (lipase synthesis) that promotes hydrolysis of fats and oils in the presence of iron salts. It is inferred that this is a result of the predominance of microorganisms producing lipases that suppress the reverse reaction).

  Invention of Claim 2 is the processing method of the fat-and-oils containing wastewater of Claim 1, and the said biological treatment is anaerobic bacteria, facultative anaerobic bacteria, fine under anaerobic environment or microaerobic environment. Anaerobic treatment that is a treatment that causes at least one action of degradation, emulsification, and dispersion by at least one microorganism selected from the group consisting of aerobic bacteria and aerobic bacteria, and a treatment product obtained by the anaerobic treatment And an aerobic treatment applied to the above.

  According to this configuration, the anaerobic treatment is performed on the concentrate obtained by the concentration and separation treatment in the presence of the iron salt prior to the aerobic treatment, so that the fat and oil concentrate is suddenly aerobic. Compared with the case where it performs, the fats and oils in a concentrate can be decomposed | disassembled effectively.

  Invention of Claim 3 is obtained by the anaerobic process between the anaerobic process and the aerobic process in the processing method of the fat-and-oil containing wastewater of Claim 1 or 2. In addition, the aerobic treatment is performed on the decomposition treatment product obtained by the decomposition treatment.

  According to this configuration, the treatment product obtained by the anaerobic treatment is subjected to the decomposition treatment by the methane-producing bacteria, thereby promoting not only the reduction of the molecular weight of the organic matter but also the volatilization by the methane gasification. Therefore, the amount of organic matter to be processed in the aerobic process following the decomposition process by the methanogen can be greatly reduced. As a result, the oil and fat content in the concentrate can be decomposed more effectively.

  Invention of Claim 4 is the processing method of the fat-and-oil containing waste water of any one of Claims 1-3, Before the said biological treatment, at least one of the said fat-and-oil containing waste water and the said concentrate. First, it is characterized by supplying an oil-degrading preparation and / or an oil-decomposing microorganism.

  According to this structure, the further fat-and-oil decomposition effect by the oil-and-oil decomposition preparation and / or oil-and-oil decomposition microorganisms is acquired in biological treatment, and the processing efficiency of the biological treatment with respect to the concentrate after concentration separation can further be improved.

  The invention according to claim 5 is an apparatus for treating fat and oil-containing wastewater, and is an input / concentration separation means for performing a concentration and separation process in which an iron salt is introduced into the fat and oil-containing wastewater to concentrate and separate the oil and fat. And biological treatment means for subjecting the concentrate obtained by the concentration and separation treatment to biological treatment.

  According to this structure, the iron salt thrown into the fat and oil containing waste water acts as an inorganic flocculant, and the fat and oil content can be stably concentrated and separated regardless of the properties of the fat and oil containing waste water. Moreover, the decomposition efficiency of the fats and oils in a concentrate can be improved by performing biological treatment to the concentrate containing an iron salt.

  Invention of Claim 6 is the processing apparatus of the fat-and-oils containing wastewater of Claim 5, The said biological treatment means is anaerobic bacteria, facultative anaerobic bacteria in anaerobic environment or microaerobic environment, Anaerobic treatment means for performing anaerobic treatment, which is a treatment that causes at least one action of degradation, emulsification and dispersion by at least one microorganism selected from the group consisting of microaerobic bacteria and aerobic bacteria; And aerobic processing means for applying aerobic processing to the processed product obtained by the sexual processing.

  According to this configuration, the anaerobic treatment is performed on the concentrate obtained by the concentration and separation treatment in the presence of the iron salt prior to the aerobic treatment, so that the fat and oil concentrate is suddenly aerobic. Compared with the case where it performs, the fats and oils in a concentrate can be decomposed | disassembled effectively.

  Invention of Claim 7 is a processing apparatus of the fats and oils containing waste water of Claim 6, It includes the decomposition treatment means for performing the decomposition process by the methanogen to the processed material obtained by the anaerobic treatment, The aerobic treatment means is an aerobic treatment means for performing an aerobic treatment on the decomposed product obtained by the decomposition treatment.

  According to this configuration, the treatment product obtained by the anaerobic treatment is subjected to the decomposition treatment by the methane-producing bacteria, thereby promoting not only the reduction of the molecular weight of the organic matter but also the volatilization by the methane gasification. Therefore, the amount of organic matter to be processed in the aerobic process following the decomposition process by the methanogen can be greatly reduced. As a result, the oil and fat content in the concentrate can be decomposed more effectively.

  Invention of Claim 8 is the processing apparatus of the fat-and-oil containing waste water of any one of Claims 5-7, Before the said biological treatment, at least one of the said fat-and-oil containing waste water and the said concentrate. It has a supply means for supplying an oil-and-oil decomposition preparation and / or an oil-and-oil decomposition microorganism to one.

  According to this structure, the further fat-and-oil decomposition effect by the oil-and-oil decomposition preparation and / or oil-and-oil decomposition microorganisms is acquired in biological treatment, and the processing efficiency of the biological treatment with respect to the concentrate after concentration separation can further be improved.

  According to the present invention, the iron salt introduced into the fat-containing wastewater acts as an inorganic flocculant, and the fat and oil can be stably concentrated and separated regardless of the properties of the fat-containing wastewater. Moreover, the decomposition efficiency of the fats and oils in a concentrate can be improved by performing biological treatment to the concentrate containing an iron salt.

It is a schematic diagram of the processing apparatus 10 of the fat and oil containing waste water which concerns on 1st Embodiment of this invention. It is a figure which shows the biological treatment means 60 concerning the 1st modification of 1st Embodiment of this invention. It is a figure which shows the biological treatment means 80 concerning the 2nd modification of 1st Embodiment of this invention. It is a schematic diagram of the processing apparatus 70 of the fat-and-oil containing waste water which concerns on 2nd Embodiment of this invention. It is a figure which shows the collection | recovery rate of the oil component collect | recovered in the fat and oil concentrate from the food factory waste water. It is a figure which shows the result of the batch type biological treatment test of the fats and oils containing waste water (raw water) of the comparative example 4.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
A method and apparatus for treating oil-containing wastewater according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a processing apparatus 10 for fat and oil-containing wastewater according to the present embodiment.

  As shown in the figure, the processing apparatus 10 for fat and oil containing wastewater supplies the fat and oil containing wastewater 1 with the supply means 15 for supplying the fat and oil decomposition preparation 4 and / or the fat and oil decomposing microorganism 6 and the fat and oil containing wastewater 1 with iron salt 2. An input / concentration separation unit 20 for performing a concentration / separation process, and a biological treatment unit 30 for performing a biological process on the concentrate 22 obtained by the concentration / separation process located downstream of the input / concentration / separation unit 20. Prepare.

  The fat-and-oil containing waste water 1 means water containing fat and oil in this specification. Examples of the fats and oils include animal and vegetable fats and oils (triglycerides and partially decomposed products thereof). Specific examples include wastewater discharged from food factories and kitchens and domestic wastewater. The fat and oil-containing wastewater 1 may further contain components other than the fat and oil components (for example, nitrogen components (ammonia nitrogen, organic nitrogen, etc.)).

  In the present invention, the fat and oil-containing wastewater 1 may have a lower limit of hexane extract concentration of 30 mg / L, preferably 50 mg / L, more preferably 100 mg / L, and an upper limit of 50,000 mg / L, preferably 30. It may be 10,000 mg / L, more preferably 10,000 mg / L. Here, the hexane extract concentration of the oil-containing wastewater 1 means a value obtained by measurement based on a factory wastewater test method (JIS K010242). In the following description, the hexane extract concentration means a value obtained by measurement by such a method.

  In the present invention, the oil-and-fat-containing wastewater 1 that has been pretreated can be subjected to a concentration and separation treatment. Therefore, what pretreated the fats and oils containing wastewater 1 corresponds to the fats and oils containing wastewater 1 in this invention. As one aspect | mode of the oil-and-fat containing waste_water | drain 1 in this invention, the dispersion water obtained by giving the pre-processing to the oil-and-fat containing waste water 1 and the dispersion | distribution process to the oil / fat containing waste water 1 is mention | raise | lifted, for example.

  The input / concentration separation means 20 is provided upstream of the concentration / separation means 24 (concentration / separation tank 24), which is a place for concentrating and separating the oil / fat content in the oil / fat containing waste water 1, and the oil / fat containing waste water. 1 and a charging means 26 for charging the iron salt 2.

  The concentration and separation means may be any means as long as it can concentrate and separate the oil and fat content in the oil and fat-containing wastewater 1. The concentration separation means used for the solid-liquid separation method can be used.

  The iron salt 2 is used as a flocculant added at the time of concentration and separation of fats and oils. Examples of the iron salt 2 to be used include ferric chloride, polyiron, ferrous chloride, ferrous sulfate and the like, and preferably ferric chloride or polyiron. In the present invention, a cationic polymer or an anionic polymer can be used as the aggregation polymer. If the mass of the hexane extract contained in the fat-and-oil containing waste water 1 is 100, the amount of iron salt 2 used is 10 to 500, preferably 50 to 300, as the mass of iron.

  In addition, it is not preferable to use PAC (polyaluminum chloride), which is a common flocculant, in the concentration treatment of the fat-and-oil-containing wastewater 1.

  The oil-degrading preparation 4 and / or the oil-decomposing microorganism 6 are additives that are supplied to at least one of the oil-containing wastewater 1 and the concentrate 22 prior to the biological treatment described later, and the biological treatment downstream by this supply. The effect that the oil-and-oil decomposition performance is improved.

  The oil-degrading microorganism 6 is a cultivated microorganism such as Acinetobacter, Alcaligenes, Arthrobacter, Bacillus, Burkho1deria, Candida, Nocardia, Pseudomonas, Rhodobacter, Rhodococcus Return sludge generated by biological treatment of the fat-and-oil containing waste water 1 or a preparation obtained by subjecting them to treatment such as concentration and drying can be used.

  When the mass of the hexane extract contained in the fat and oil-containing wastewater 1 is 100, the addition amount of the fat-and-oil decomposing microorganism 6 is in the range of 10 to 300, preferably 30 to 100, as the dry mass of the microorganism.

  The oil-degrading preparation 4 is not limited as long as it promotes the decomposition of fats and oils, and lipases that catalyze the hydrolysis of fats and oils, emulsifiers for improving the dispersibility of fats and oils, and microbial preparations containing fat-decomposing microorganisms can be used. Is possible.

  The concentrate 22 obtained by the concentration separation means (concentration separation tank 24) is subjected to biological treatment by the biological treatment means 30.

  In the present embodiment, the biological treatment means 30 includes an anaerobic treatment means (anaerobic treatment tank 34) where the anaerobic treatment is performed on the concentrate 22, and an anaerobic treated water 36 obtained by the anaerobic treatment. An aerobic treatment means (aerobic tank 38) serving as a place where an aerobic treatment is applied to the aerobic treatment, and an activated sludge treatment which is a further aerobic treatment for the aerobic treatment water 40 obtained by the aerobic treatment. Aerobic treatment means (activated sludge treatment means 50) to be applied.

  The anaerobic treatment means is not particularly limited as long as it can obtain the anaerobic treated water 36 by performing the anaerobic treatment described later on the oil / fat concentrate 22. For example, the oil and fat concentrate is received in a sealed container having anaerobic bacteria living in an anaerobic environment, and the anaerobic bacteria are allowed to act on this to discharge anaerobic treated water.

  Further, for example, a container having at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria living in a microaerobic environment, The thing which accepts a thing inside and makes this act at least 1 chosen from the group which consists of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria, and discharges anaerobic treated water 36 is mentioned. . Whatever container is used, it is preferable to have a device capable of stirring the inside thereof.

  As the anaerobic treatment means, it is possible to use an apparatus that performs a conventionally known treatment such as an anaerobic fixed bed method, an anaerobic fluidized bed method, a UASB method, an EGSB method, or the like. However, as will be described later, the anaerobic treatment in the present invention is performed under the condition that the decomposition (methane fermentation) by the methane-producing bacteria does not proceed in principle, so ancillary equipment such as a gas holder for storing methane gas and a desulfurization treatment device is used. It does not have to be.

  The anaerobic treatment means preferably further has means capable of adjusting the pH, temperature, and oxidation-reduction potential of the concentrate 22 (the contents of the tank when a reaction tank is used in the anaerobic treatment means). The pH and temperature can be adjusted by known acid or alkali addition means or heating means. The oxidation-reduction potential can be adjusted by applying anaerobic treatment while supplying an appropriate amount of oxygen to the fat and oil concentrate.

  Anaerobic water 36 obtained in the anaerobic treatment means (anaerobic treatment tank 34) is transferred to the downstream aerobic treatment means (aerobic tank 38).

  As the aerobic treatment means, conventionally known means used for aerobic biological treatment can be used. Specifically, the anaerobic treated water 36 is received in the tank, and is a means capable of performing aeration while stirring. For example, a conventionally known floating biological treatment method (batch activated sludge method, continuous activated Examples include aerobic treatment means used in the implementation of sludge methods, membrane separation activated sludge methods, etc.) and biofilm treatment methods (rotary disc method, aerobic filtration method, fluidized bed method, etc.). In addition, the aerobic treatment means may store sludge (for example, activated sludge etc.) inside, and in that case, it is preferable to have a configuration that can discharge this.

  Moreover, the processing apparatus of the fat and oil containing waste water may use two or more aerobic processing means. For example, the first aerobic processing unit may perform aerobic processing, and the second aerobic processing unit may perform aerobic processing.

  Furthermore, it is preferable that the aerobic treatment means includes a solid-liquid separation means. In this case, the sludge stored in the aerobic treatment means can be discharged promptly. Further, the aerobic treatment described later includes activated sludge treatment, and therefore the aerobic treatment means includes activated sludge treatment means.

  In general, the activated sludge treatment means includes an aeration tank and a sedimentation tank, and flocs of activated sludge that has migrated from the aeration tank, which is a place where activated sludge treatment is performed, is separated by natural sedimentation in the sedimentation tank.

  In the processing apparatus 10 for fat and oil-containing wastewater according to the present embodiment, two aerobic treatment means that perform aerobic treatment, that is, the aerobic tank 38 and the activated sludge treatment means 50 are respectively provided downstream of the anaerobic treatment means. They are arranged in series.

  The activated sludge treatment means 50 is an activated sludge tank 42 (aeration tank) that is aerated and becomes a place for aerobic treatment with activated sludge, and the activated sludge that is disposed downstream of the activated sludge tank 42 and has migrated from the activated sludge tank 42. And a sedimentation tank 46 for separating the flocs by natural sedimentation. The separation liquid separated from the activated sludge floc in the settling tank 46 is finally discharged as the biologically treated water 32 from the treatment apparatus 10 for fat and oil containing wastewater.

  A method for treating oil-containing wastewater using the oil-containing wastewater treatment apparatus 10 having the above configuration will be described below.

[1. Concentrated separation process]
First, the fat and oil-decomposing preparation 4 and / or the fat-and-oil decomposing microorganism 6 are supplied to the fat and oil-containing waste water 1 through the supply means 15 and the iron salt 2 is charged in the above-described amount through the input means 26 and concentrated and separated. The oil and fat is concentrated and separated in the (concentration / separation tank 24).

  Although there is no particular limitation on the order in which the oil-degrading preparation 4 and / or the oil-decomposing microorganism 6 and the iron salt 2 are added to the oil-containing wastewater 1, the oil-decomposing preparation 4 and / or the oil-decomposing microorganism 6 is used as the oil-containing wastewater 1. It is preferable that the iron salt 2 is subsequently charged and stirred after the charging and stirring because the oil and fat decomposition performance in biological treatment described later is improved.

  It is preferable that the hexane extract substance contained in the oil / fat concentrate 22 is concentrated 10 times or more with respect to the hexane extract substance concentration of the oil / fat-containing wastewater 1 and further concentrated 40 to 50 times or more. More preferably. When the concentration rate of the concentrate 22 in the concentration process is increased, it becomes possible to perform biological treatment of the concentrate 22 in a smaller amount compared to the case where the concentrate with a low concentration rate is biologically treated. When the extracted substance is biologically treated, the reaction time of the concentrate 22 in the biological treatment means 30 can be increased as compared with the case of biologically treating a concentrate having a small concentration ratio.

  Oil and fat components generally exist as solids in wastewater, and during biological treatment, the decomposition of the oil and fat components proceeds from the surface to the inside of the solids. Therefore, decomposition of fats and oils progresses by being able to take time for biological treatment, and it leads to improvement of the quality of the biologically treated water obtained. That is, when the concentration ratio of the concentrate 22 in the concentration process is increased, the biological treatment time for the concentrate 22 can be relatively long, and the water quality after the treatment is improved.

  In general, it is said that the activity of biological sludge is inhibited when the hexane extraction concentration in the oil-containing wastewater 1 is 150 mg / L or more, but in the present invention, the concentration of oil and fat with a hexane extraction concentration of 20,000 mg / L is concentrated. It was revealed that even a product can be satisfactorily treated without being affected by inhibition.

  The fat and oil-containing wastewater 1 is separated into a fat and oil concentrate 22 and separated water 28 by the concentration treatment, and the concentrate 22 is transferred to the biological treatment means 30 and subjected to biological treatment (concentration treatment).

[2. Biological treatment]
In the present invention, biological treatment includes both aerobic treatment and anaerobic treatment. In the method for treating oil-containing wastewater of the present invention, the biological treatment includes a case where an aerobic treatment is performed after an anaerobic treatment or an aerobic treatment.

  In the present embodiment, the biological treatment is performed by two anaerobic treatment means (the aerobic tank 38 and the activated sludge treatment means 50, respectively) arranged in series after the anaerobic treatment in the anaerobic treatment means (anaerobic tank 34). Aerobic treatment of 1 time.

[2-1. Anaerobic treatment]
The concentrate 22 is transferred to anaerobic treatment means (anaerobic tank 34) and subjected to anaerobic treatment.

  In the anaerobic treatment, in an anaerobic environment or a microaerobic environment, at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria is converted into an oil concentrate. It is a treatment that promotes emulsification and dispersion of fats and oils by metabolites such as biosurfactants produced by these fungi, and hydrolyzes them with enzymes such as lipase, by acting on the contained fats and oils. In principle, this means a treatment that does not involve the generation of methane gas that accompanies decomposition by a methanogen that is an anaerobic bacterium. Therefore, the anaerobic process in the present invention is a process different from the conventional anaerobic digestion.

  An anaerobic environment or a microaerobic environment refers to a state where the dissolved oxygen concentration (DO) is 0 to 0.3 mg / L and the oxidation-reduction potential measured with a platinum electrode is +50 mV or less.

  Conventional anaerobic digestion (anaerobic biological treatment) means a biological treatment method in which organic substances are decomposed into methane gas or carbon dioxide gas by the metabolic action of anaerobic bacteria growing in an anaerobic environment. Here, the decomposition path from organic matter to methane gas is considered to consist of three stages. Specifically, the first stage of solubilization and low molecular weight hydrolysis of organic substances, and then the low molecular weight substance. It is considered that it consists of three stages: a second stage in which volatile fatty acids and alcohols are produced by acid fermentation, and finally a third stage in which methane gas is produced from acetic acid or hydrogen and carbon dioxide.

  On the other hand, since the anaerobic treatment in the present invention does not include the decomposition reaction (methane gas generation reaction) corresponding to the third stage in the conventional anaerobic digestion in principle, no methane gas is generated. In addition, the present inventors estimate that the decomposition reaction (acid fermentation) corresponding to the second stage is not substantially included. Furthermore, the decomposition reaction (hydrolysis) corresponding to the first stage is significantly accelerated by the addition of a high concentration of iron salt.

  According to conventional knowledge, iron is known to strongly inhibit the reaction of lipase that catalyzes the decomposition reaction of fats and oils, so there are almost no detailed examples of fat and oil decomposition under the condition of adding high concentration iron salt. It was not known. In the present invention, as a result of conducting a biological treatment test using a high concentration of iron salt for a long period of time, hydrolysis of fats and oils is promoted with a high concentration of iron salts and / or a fat and oil synthesis reaction which is a reverse reaction of lipase. The inventors presume that a phenomenon that can be suppressed has appeared, and further, the inventors have considered the possibility that the microorganisms producing lipase having the properties showing the above phenomenon have become dominant. Estimated.

  The anaerobic treatment in the present invention includes, for example, conditions (time, pH, and the like) that cause at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria, and aerobic bacteria to the fat and oil concentrate. The temperature can be adjusted.

  It is preferable to carry out the reaction under the following conditions because emulsification of fats and oils by metabolites such as biosurfactant and decomposition by enzymes such as lipase tend to proceed.

  In the anaerobic treatment, it is preferable that the lower limit of the time for allowing at least one selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria to act on the oil and fat concentrate is 20 hours. Two days are more preferable, and three days are more preferable. The upper limit of this time is preferably 15 days, and more preferably 10 days. Although the processing time in a conventionally well-known anaerobic digestion is about 30-40 days, since the anaerobic processing in this invention does not perform reaction of methane fermentation, it can be made into a shorter time.

  The anaerobic treatment is preferably performed at a reaction pH of 7.2 or higher. Further, this pH is preferably set to 11.0 or less, more preferably 8.8 or less.

  The anaerobic treatment is preferably performed at a reaction temperature of 20 ° C or higher, more preferably 30 ° C or higher. Moreover, it is preferable to perform this temperature as 58 degrees C or less, and it is more preferable to carry out as 47 degrees C or less.

  When anaerobic treatment is performed by causing microaerobic bacteria, aerobic bacteria or facultative anaerobic bacteria to act on the oil and fat concentrate, for example, a limited oxygen supply different from the conventionally known aeration treatment is applied to the oil and fat concentrate. It is preferable to carry out. At this time, it is preferable to perform the anaerobic treatment by adjusting so that the measured value of the oxidation-reduction potential is +50 mV or less, more preferably −50 mV or less, and further preferably −50 to −250 mV.

  In addition, when anaerobic bacteria are allowed to act on the oil / fat concentrate, anaerobic treatment is performed by adjusting the measured value of the oxidation-reduction potential to be preferably −200 mV or less, more preferably −300 mV or less. Shall be applied.

  In the present invention, the oxidation-reduction potential means a value obtained by measurement by an ORP electrode method using a platinum electrode (hereinafter, anaerobic treatment).

  Anaerobic water 36 obtained by anaerobic treatment in the anaerobic treatment means (anaerobic tank 34) is transferred to the downstream aerobic treatment means (aerobic tank 38) and subjected to aerobic treatment.

[2-2. Aerobic treatment]
In the present invention, the aerobic treatment means a treatment in which microorganisms mainly composed of aerobic bacteria that live in an aerobic environment are allowed to act on the oil / fat concentrate and decompose.

  An aerobic environment is an environment in which oxygen is supplied, and refers to a state where the dissolved oxygen concentration (DO) is 0 mg / L or more.

  As the aerobic treatment of the present invention, for example, a conventionally known aerobic biological treatment can be applied. Specifically, the process of accepting an oil and fat concentrate in a tank and aeration while stirring is exemplified. More specifically, conventionally known floating biological treatment methods (batch activated sludge method, continuous activated sludge method, membrane separation activated sludge method, etc.) and biological membrane treatment methods (rotating disc method, aerobic filter bed method, A fluidized bed method).

  The aerobic treatment preferably includes a plurality of types of treatment. For example, it is preferable to apply the fluidized bed method after applying the continuous activated sludge method to the fat and oil concentrate. Moreover, it is preferable that it is the process which applies a continuous activated sludge method after performing an aeration process to fat and oil concentrate. Further, a denitrification step may be incorporated into the above process.

  When the aerobic treatment includes a plurality of types of treatment, it is preferable to include a conventionally known activated sludge treatment as one of them. In such a case, the cleanness of the aerobic treated water finally obtained is further increased, and aerobic treated water having a hexane extract concentration that satisfies the sewage discharge standard value stipulated in the Sewerage Law can be obtained.

  The aerobic treatment in the present invention can be performed, for example, by adjusting conditions (time, pH, temperature, etc.) that cause the aerobic bacteria or the like to act on the fat and oil concentrate.

  In the aerobic treatment, the lower limit of the time for aerobic bacteria and the like to act on the oil and fat concentrate is preferably 5 hours, more preferably 3 days, and even more preferably 4 days. The upper limit of this time is preferably 14 days, and more preferably 10 days. This is because if the time for allowing the aerobic bacteria to act on the oil / fat concentrate is within such a range, a more aerobic treated water with higher cleanliness can be obtained.

  In addition, when performing an aerobic process of 2 steps | paragraphs or more, the sum total of the processing time in each step shall be equivalent to the time which an aerobic microbe acts on the fat and oil concentrate as mentioned above.

  The aerobic treatment is preferably carried out at a pH of 7.2 or higher, preferably 7.5 or higher, when the oil / fat concentrate (when using a reaction vessel in the aerobic treatment). The pH is preferably 11.0 or less, and preferably 9.0 or less. This is because if the fat and oil concentrate is subjected to an aerobic treatment in such a range of pH, an aerobic treated water having a higher cleanliness can be obtained.

  The aerobic treatment is preferably performed at a temperature of the oil / fat concentrate (when a reaction vessel is used in the aerobic treatment, the content of the vessel) at 20 ° C. or higher, and more preferably at 39 ° C. or higher. Moreover, it is preferable to perform this temperature as 58 degrees C or less, and it is more preferable to carry out as 48 degrees C or less. This is because when the aerobic concentrate is subjected to an aerobic treatment at a temperature in such a range, a more aerobic treated water with higher cleanliness can be obtained.

  The aerobic treatment is preferably performed by setting the ratio of the mass of the oil and fat in the oil and fat concentrate to the mass of the nitrogen atom (nitrogen atom / oil and fat content) as 0.05 or more, more preferably 0.1 to 0.5. preferable.

  The aerobic treatment is preferably performed by setting the ratio of the mass of the fat and oil to the mass of the phosphorus atom (phosphorus / fat and fat content) in the oil and fat concentrate as 0.01 or more, and preferably from 0.05 to 0.1.

  It is preferable to replenish nutrients such as a nitrogen source during the aerobic treatment so that the mass ratio of nitrogen, phosphorus and fats and oils is obtained.

  The aerobic treatment is preferably performed so that the dissolved oxygen amount (DO) in the oil / fat concentrate (the content of the tank when a reaction vessel is used in the aerobic treatment) is 1.0 mg / L or more, 2.0 mg It is more preferable to carry out so that it may become / L or more, and it is still more preferable to carry out so that it may become 3.0 mg / L or more. This is because an aerobic treated water having a higher cleanliness can be obtained. The amount of dissolved oxygen can be measured with a conventionally known DO meter.

  In this embodiment, two types of aerobic treatments are included one by one. That is, after the aerobic treatment in the first aerobic treatment means (aerobic tank 38), the aerobic treatment water 40 obtained is further favored in the second aerobic treatment means (activated sludge treatment means 50). Perform tempering.

  After the second stage of aerobic treatment, that is, activated sludge treatment (aerobic treatment) in the activated sludge tank 42, the activated sludge treated water 44 containing activated sludge is transferred to the settling tank 46 and spontaneously settled in the settling tank 46. Is separated into biologically treated water 32, return sludge 56 and surplus sludge 52 (above, aerobic treatment).

  The surplus sludge 52 merges with the biologically treated water 32 within a range allowed through the path 54. Further, the return sludge 56 may be returned to anaerobic treatment means (anaerobic tank 34) and / or aerobic treatment means (aerobic tank 38, activated sludge tank 42, etc.) as shown in FIG. Thereby, an anaerobic process and / or an aerobic process are further accelerated | stimulated, and the process quality of the biologically treated water 32 finally obtained improves.

  Further, as described above, the return sludge 56 may be supplied as the oil-degrading microorganism 6 to the oil-containing wastewater 1 and the oil-and-fat concentrate 22 before biological treatment.

  When the separated water 28 separated in the concentration separation means (concentration separation tank 24) is subjected to aerobic treatment by two or more aerobic treatment means as in the present embodiment, the last aerobic treatment means ( That is, in this embodiment, it is preferable that the activated sludge tank 42) in the activated sludge treatment means 50 is supplied. Since the separated water 28 contains fats and oils remaining in the separated water 28 without being concentrated in the concentrated separation means (concentrated separation tank 24), it is applied by being supplied to the last aerobic treatment means as described above. This is because the oil and fat can also be decomposed.

  Further, the separated water 28 may be supplied to the settling tank 46 downstream of the activated sludge tank 42 depending on the degree of oil and fat remaining in the separated water 28.

  In the present embodiment, two aerobic treatment means (ie, the aerobic tank 38 and the activated sludge treatment means 50) are arranged in series as the aerobic treatment means in the biological treatment means. However, the present invention is not limited to this. Is not to be done.

  Hereinafter, a modified example (hereinafter referred to as a first modified example) of the aerobic processing means will be described with reference to FIG. In FIG. 2, elements similar to those of the embodiment shown in FIG. 1 described above are denoted by the same reference numerals and description thereof is omitted. FIG. 2 is a schematic diagram showing the biological treatment means 60 according to the first modification.

  As illustrated, the biological treatment means 60 according to the first modification includes an anaerobic treatment means (anaerobic tank 34), one aerobic treatment means (aerobic tank 62) disposed downstream of the anaerobic treatment means, Have

  In the first modification, the aerobic tank 62 that is an aerobic treatment means is partitioned into a front stage part 62b and a rear stage part 62c by a partition part 62a. Therefore, according to the aerobic processing means (aerobic tank 62) according to this modification, the first-stage aerobic process is performed by the front-stage part 62b, and the second-stage aerobic process is performed by the rear-stage part 62c. Can be applied. Therefore, by increasing the number of partition portions, it is possible to perform a plurality of stages of aerobic processing by one aerobic processing means.

  Moreover, in the said embodiment, although the biological treatment means has the structure which has an anaerobic treatment means and an aerobic treatment means, it is not limited to this.

  Hereinafter, a modification of the biological treatment means (hereinafter referred to as a second modification) will be described with reference to FIG. In FIG. 3, the same elements as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. FIG. 3 is a schematic diagram showing the biological treatment means 80 according to the second modification.

  In the biological treatment means 80 according to this modification, a methane fermentation tank 82 (decomposition treatment means) is provided downstream of the anaerobic tank 34 (anaerobic treatment means), and an aerobic tank 38 (first assembly) is provided downstream of the methane fermentation tank 82. The aerobic treatment means) is different from the biological treatment means 30 of the first embodiment.

  The methane fermentation tank 82 (decomposition processing means) serves as a place where the anaerobic water 36 (processed product) obtained by the anaerobic process is subjected to a decomposition process using methane-producing bacteria. As described above, the decomposition treatment with methane-producing bacteria means biological treatment that decomposes organic substances into methane gas or carbon dioxide gas by the metabolic action of anaerobic bacteria that grow in an anaerobic environment.

  As the decomposition treatment means, as in the anaerobic treatment means, a conventionally known apparatus such as an anaerobic fixed bed method, anaerobic fluidized bed method, UASB method, EGSB method or the like can be used. Unlike the above-described anaerobic treatment means, a gas holder for storing methane gas and ancillary equipment such as a desulfurization treatment apparatus are required.

  In addition, the decomposition treatment by the methanogen is a treatment accompanied by the generation of methane gas due to the decomposition by the methanogen that is an anaerobic bacterium, and does not involve the methane gas generation reaction. Is a different process.

  The difference between the anaerobic treatment in which no methane gas is generated and the treatment with the methanogen can be shown, for example, as follows. That is, while the HRT (hydraulic residence time) of the anaerobic treatment is 20 hours to 10 days, the HRT of the treatment with the methanogen is as long as 15 to 30 days. This is because methanogens have a slow growth rate and require a long residence time.

  In addition, the ORP for the anaerobic treatment is +50 to −300 mV, while the ORP for the treatment with the methanogen is as small as −330 mV or less. This is because, unlike methane fermentation, advanced anaerobic conditions are not always essential in anaerobic treatment, and even if air flows into the tank within the range of the ORP, it does not matter.

  According to the present modified example (second modified example), the anaerobic treated water 36 after the anaerobic treatment is subjected to the decomposition treatment by the methanogenic bacteria, thereby not only reducing the molecular weight of the organic matter but also by methane gasification. Volatilization is promoted. Therefore, the amount of organic matter to be processed in the aerobic process following the decomposition process by the methanogen can be greatly reduced.

  As a result, the effect of greatly improving the decomposition rate of n-hexane in the biologically treated water after the aerobic treatment is obtained.

(Second Embodiment)
Next, with reference to FIG. 4, a second embodiment of the method and apparatus for treating fat and oil-containing wastewater will be described mainly with respect to the differences from the first embodiment. FIG. 4 is a schematic diagram of a processing apparatus 70 for fat and oil-containing wastewater according to the second embodiment of the present invention. It should be noted that the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The oil-and-fat-containing wastewater treatment apparatus 70 according to the present embodiment includes an input / concentration separation unit 20 for introducing the iron salt 2 into the fat / fat-containing wastewater 1 and subjecting it to concentration separation processing, and a downstream of the input / concentration separation unit 20. And biological treatment means (biological treatment tank 74) for subjecting the concentrate 22 obtained by the concentration separation process to biological treatment.

  The charging / concentrating / separating means 20 is not different from that of the first embodiment, and thus the description thereof is omitted.

  The biological treatment means 30 is an aerobic treatment means (biological treatment tank 74) serving as a place for performing the aerobic treatment as described in the first embodiment, and performs one-stage aerobic treatment. is there.

  That is, in the present embodiment, compared with the first embodiment, there is no supply means for supplying the oil-degrading preparation 4 and / or the oil-decomposing microorganism 6, and one-stage aerobic treatment is performed. The difference is that only processing is performed.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
FIG. 4 shows ferric chloride in food factory wastewater 1 (corresponding to oil-containing wastewater 1) with BOD (biological oxygen demand) = 580 mg / L, SS = 408 mg / L, and hexane extractant = 400 mg / L. It added at the density | concentration of 1-800 mg / L in Fe conversion, and pH was adjusted to 7.0. Thereafter, an anionic polymer (Ebagulose A-151, product of Watering Co., Ltd.) was added at a concentration of 1 mg / L, and equal amounts of pressurized water pressurized to 4 kg / cm ² were mixed and subjected to floating separation.

  Next, the same flotation separation process was performed in the same procedure for food factory wastewater 2 (corresponding to oil-containing wastewater 1) collected at different times.

  The values of BOD, SS, and hexane extractable substances in food factory wastewater 1 and food factory wastewater 2 are almost the same. SS is a suspended substance and is one of the indicators of turbidity of water. Particles contained in water are filtered through glass fiber filter paper or MF membrane filter paper having a pore diameter of 1 μm, and the dry weight of the particles. (Mg / L).

[Comparative Example 1]
PAC (polyaluminum chloride) was used in place of ferric chloride, and the other operations were the same as in Example 1 and the pressure levitation treatment was performed.

  In Example 1 and Comparative Example 1, the amount of the hexane extractable substance in the oil and fat concentrate that was floated and separated was specified, and the recovery rate of the oil recovered in the oil and fat concentrate from the food factory wastewater 1 and 2 was calculated. . The results are shown in FIG.

  FIG. 5 is a graph showing the amount of the flocculant added to the wastewater from the food factory (mg / L in terms of Fe and Al, respectively) on the horizontal axis and the oil recovery rate (%) on the vertical axis.

  As shown in the figure, when ferric chloride was used as the flocculant, the fat and oil components contained in the wastewater could be stably separated and recovered regardless of the lot of wastewater.

  On the other hand, when PAC was used as the flocculant, the recovery of the oil and fat component from the food factory wastewater 1 was good, but the recovery rate of the oil and fat component from the food factory wastewater 2 deteriorated.

  Therefore, when iron salt was thrown into the fat and oil containing wastewater as an inorganic flocculant, it was confirmed that the fat and oil content could be stably concentrated and separated regardless of the properties of the fat and oil containing wastewater.

[Example 2]
A mixture of commercially available mayonnaise and margarine in a mass ratio of 1: 1 is used as an oil and fat raw material, and this is added to city water to adjust the hexane extractant to 400 mg / L. Assumed.

  Then, ferric chloride is 1 mg / L (condition (1)), 20 mg / L (condition (2)), 100 mg / L (condition (3)) in terms of iron with respect to the oil-containing wastewater (raw water). , 400 mg / L (Condition (4)), 800 mg / L (Condition (5)), and concentrated to separate 40 times to obtain a fat and oil concentrate (corresponding to Concentrate 22) Assuming the case, ferric chloride in city water is 40 mg / L (condition (1)), 800 mg / L (condition (2)), 4,000 mg / L (condition (3)) in terms of iron, 16 , 2,000 mg / L (Condition (4)) and 32,000 mg / L (Condition (5)), respectively, and the oil and fat raw material was added so that the hexane extractant concentration would be 16,000 mg / L. What was added was made into the concentrate of the fats and oils assumed.

  Next, a 2 L reaction vessel is prepared as a one-stage biological treatment means (corresponding to the biological treatment tank 74) for the concentrates of the conditions (1) to (5), and the reaction conditions are 37 ° C. and pH 7.5. A continuous biological treatment (aerobic treatment) test of the concentrates of the conditions (1) to (5) was performed at a setting of ˜8.2, a dissolved oxygen concentration of 1.0 mg / L, and a residence time of 320 hours.

[Comparative Example 2]
A liquid assumed to be raw water for fat-containing wastewater in Example 2 (that is, a mixture of commercially available mayonnaise and margarine in a mass ratio of 1: 1 was used as a fat raw material, and this was added to city water to give 400 mg of hexane extract. Ferric chloride was added at a concentration of 1 mg / L in terms of iron.

  For this raw water, a 2 L reaction vessel is prepared as a one-stage biological treatment means (corresponding to the biological treatment tank 74), the reaction conditions are 37 ° C., pH 7.5 to 8.2, and the dissolved oxygen concentration is 1.0 mg / L. Then, a continuous biological treatment (aerobic treatment) test was performed with a residence time of 8 hours.

  Note that the residence time was set to 8 hours because the hexane extractant concentration of the raw water of Comparative Example 2 was 1/40 compared to the hexane extractant concentration of 16,000 mg / L of the concentrate of Example 2. Therefore, the reaction time of Comparative Example 2 is set to 1/40 of 8 hours with respect to Example 2.

  The results are shown in Table 1.

※1：比較例２にいう原水のヘキサン抽出物質濃度を示す。
※2：実施例２の条件(1)〜(5)の４０倍濃縮を想定した濃縮物のヘキサン抽出物質濃度を示す。
※3：比較例２においては、直接添加した鉄塩のＦｅ換算量であり、実施例２(1)〜(5)においては、濃縮物を原水レベルまで希釈（４０倍希釈）したと想定した場合の鉄塩のＦｅ換算量を示す。
※4：原水ｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）に対する、原水レベルまで濃縮物を希釈（４０倍希釈）したと想定した場合の鉄塩のＦｅ換算量の比を示す。すなわち、原水あたりのｎ−Ｈｅｘ量に対する添加された鉄塩のＦｅ換算量の比である。
※5：生物処理試験後の生物処理水のヘキサン抽出物質濃度を示す。
※6：比較例２においては、原水ｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）と生物処理水のｎ−Ｈｅｘ濃度との差分から算出されるヘキサン抽出物質の分解率であり、実施例２(1)〜(5)においては、原水ｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）（４００ｍｇ／Ｌ）と生物処理水のｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）を４０で除した値との差分から算出されるヘキサン抽出物質の分解率を示す。

* 1: Indicates the concentration of raw water hexane extract in Comparative Example 2.
* 2: Concentration of hexane extract in concentrated product assuming 40-fold concentration of conditions (1) to (5) in Example 2.
* 3: In Comparative Example 2, this is the Fe equivalent amount of iron salt added directly. In Examples 2 (1) to (5), it was assumed that the concentrate was diluted to the raw water level (40-fold dilution). In this case, the iron equivalent amount of the iron salt is shown.
* 4: The ratio of the iron equivalent of iron salt when the concentrate is diluted (diluted 40 times) to the raw water level relative to the raw water n-Hex concentration (mg / L). That is, it is the ratio of the iron equivalent amount of the added iron salt to the n-Hex amount per raw water.
* 5: Indicates the concentration of hexane extractables in biologically treated water after the biological treatment test.
* 6: In Comparative Example 2, the rate of decomposition of the hexane extractant calculated from the difference between the n-Hex concentration of raw water (mg / L) and the n-Hex concentration of biologically treated water. Example 2 (1) In (5), hexane calculated from the difference between the n-Hex concentration of raw water (mg / L) (400 mg / L) and the n-Hex concentration of biologically treated water (mg / L) divided by 40 Indicates the decomposition rate of the extracted substance.

  As shown in Table 1, the condition (1) of Comparative Example 2 and Example 2 is that the amount of iron added per fat component contained per raw water (Fe conversion amount) is biologically treated under the same conditions. In the condition (1) of Example 2 where the oil and fat component was concentrated and separated, the decomposition ratio of the oil and fat component was improved by 10% compared to Comparative Example 2.

  Even if the liquid has the same amount of hexane extractant, the volume of the liquid having a small concentration of hexane extractant is increased. Therefore, when biological treatment is performed in a fixed volume tank in the same time, a liquid having a large volume (that is, a liquid having a low hexane extraction concentration) has a shorter residence time in the biological treatment tank, and a liquid having a small volume (that is, a liquid having a small volume) The liquid having a high concentration of hexane extractable substance) can take a long residence time in the biological treatment tank.

  Furthermore, as described above, the oil and fat component generally exists as a solid in the liquid, and during the biological treatment, the oil and fat component proceeds from the surface of the solid to the inside. Therefore, being able to take a long biological treatment time leads to the decomposition of fats and oils and improvement of the quality of the biological treated water obtained.

  That is, in condition (1) of Example 2, since the residence time of the oil and fat component is longer than that of Comparative Example 2, the decomposition proceeds more and the purification of the biologically treated water further proceeds.

  Furthermore, according to Table 1, the value of the ratio (B) / (A), that is, the “total amount of iron per unit volume of oil-containing wastewater (see paragraph [0024])” in Patent Document 2 is “same The weight ratio of iron to the load of normal hexane extract per unit volume of fat and oil-containing wastewater (see the same paragraph) is a very large value of 0.0025 to 2, and the inventors In the conditions (1) to (5) of 2, it was found that the treatment water quality of the biologically treated water becomes better as the amount of iron salt added is increased.

As a result, it was found in Patent Document 2 that “the total amount of iron per unit volume of fat-containing wastewater is greater than 30 × 10 ^{−3 in} weight ratio to the load of normal hexane extract per unit volume of fat-containing wastewater. be supplied iron salts to the first treatment tank 10, activity of microbial sludge in the first treatment tank 10, in a weight ratio to the load of normal hexane extract 1.0 × 10 ^-3 or more 30 × 10 ^{- The} result is different from the result of “not much different from the range of ³ or less (same paragraph)”.

In other words, even when the mass ratio of iron salt to the amount of normal hexane extractables per raw water (Fe equivalent) exceeds 1.0 × 10 ⁻³ , when biological treatment is performed, the total amount of iron increases. It was found that the decomposition efficiency of fats and oils was improved.

[Example 3]
A mixture of commercially available mayonnaise and margarine in a mass ratio of 1: 1 is used as an oil and fat raw material, and this is added to city water to adjust the hexane extractant to 400 mg / L. Assumed.

  Assuming the case where ferric chloride is added to the oil-containing wastewater (raw water) so as to be 400 mg / L in terms of iron, and concentrated and separated 40 times to obtain a concentrate, ferric chloride is added to city water. Is added at a concentration of 16,000 mg / L in terms of iron, and the above oil and fat raw material is added so that the concentration of the hexane extract is 16,000 mg / L. 6)).

  Further, it is assumed that the same iron content, the same fat content and the same concentration ratio as in the condition (6) are added, and the fat-decomposing microorganism is added at a concentration of 200 mg-SS / L per fat-containing waste water (raw water). Then, ferric chloride in city water is obtained at a concentration of 16,000 mg / L in terms of iron, and the above oil and fat raw material is obtained as a hexane extract substance at a concentration of 16,000 mg / L under the condition (4) of Example 2. The one obtained by adding sludge in a biological treatment tank at a concentration of 8,000-SS / L was used as a fat and oil concentrate (condition (7)).

  Prepare a 0.6L reaction vessel and a 1.4L reaction vessel as biological treatment tanks, anaerobic tanks used for anaerobic treatment (anaerobic treatment means) and aerobic tanks used for one-stage aerobic treatment (late treatment) Means). The reaction conditions of the anaerobic tank were set to 37 ° C., pH 7.5 to 8.5, and the residence time was 96 hours. The reaction conditions of the aerobic tank were 37 ° C., pH 7.5 to 8.2, and the dissolved oxygen concentration was 1.0 mg / L and the continuous treatment test of the fat and oil concentrate was done by the setting of residence time 224 hours.

[Comparative Example 3]
The iron salt used in preparing the oil / fat concentrate of Example 3 was changed to PAC, and the addition concentration of PAC was 400 mg / L in terms of Al per oil-containing wastewater (raw water) and concentrated 40 times. Assuming the case where a concentrate is obtained by separation, a concentrate obtained by adding ferric chloride to city water at a concentration of 16,000 mg / L in terms of iron (Comparative Example 3) It was.

  The other conditions were the same as those for preparing the fat concentrate described in the condition (6) of Example 3, and the fat concentrate was adjusted. The fat and oil concentrate of Comparative Example 3 was also subjected to the same biological treatment test as that of Example 3.

  Table 2 shows the test conditions of Example 3 and Comparative Example 3, and Table 3 shows the results of the biological treatment test of Example 3 and Comparative Example 3.

※7：油脂含有排水（原水）のヘキサン抽出物濃度を示す。
※8：４０倍濃縮を想定した油脂濃縮物のヘキサン抽出物質濃度を示す。
※9：油脂濃縮物を４０倍希釈した場合の鉄塩のＦｅ換算量を示す。
※10：油脂濃縮物を４０倍希釈した場合のＰＡＣのＡｌ換算量を示す。
※11：嫌気槽での嫌気性処理により得られた嫌気処理水のヘキサン抽出物濃度を示す。
※12：嫌気処理水に対して好気槽にて好気性処理を施し、得られた生物処理水のヘキサン抽出物濃度を示す。
※13：油脂含有排水（原水）ｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）と生物処理水のｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）を４０で除した値との差分から算出されるヘキサン抽出物質の分解率を示す。

* 7: Indicates the hexane extract concentration of oil-containing wastewater (raw water).
* 8: Indicates the concentration of the hexane extract of the oil / fat concentrate assuming a 40-fold concentration.
* 9: Indicates the Fe equivalent amount of iron salt when the fat and oil concentrate is diluted 40 times.
* 10: Indicates the PAC Al equivalent amount when the fat and oil concentrate is diluted 40 times.
* 11: Indicates the hexane extract concentration of anaerobic treated water obtained by anaerobic treatment in an anaerobic tank.
* 12: Indicates the concentration of hexane extract in biologically treated water obtained by subjecting anaerobic treated water to aerobic treatment in an aerobic tank.
* 13: Decomposition of hexane-extracted material calculated from the difference between n-Hex concentration (mg / L) of fat and oil-containing wastewater (raw water) and n-Hex concentration (mg / L) of biologically treated water divided by 40 Indicates the rate.

  As understood from the comparison between Table 1 and Table 3, when anaerobic treatment is introduced in the first half of biological treatment in Example 3- (6) as compared with Example 2- (4), the decomposition rate of fat and oil components Was improved by 2%.

  Moreover, in Example 2- (4), although not described in the table, troubles such as undegraded oil floating on the upper part of the aerobic tank and occurrence of oil residue were occasionally observed during biological treatment. However, Example 3- (6) was able to show that introduction of anaerobic treatment enabled stable treatment without the generation of oil residue.

  Conventionally, when the aerated treatment (aerobic treatment) is directly applied to the concentrated oil / fat component as in the prior art of Patent Document 1, undecomposed oil / fat removes oil / fat residue in the course of treatment due to the aeration treatment. There was a defect of forming. As such oil and fat residue, for example, there is an oil ball, and the oil and fat residue is difficult to be decomposed, so that the decomposition process has taken a very long time. According to the present invention, the anaerobic treatment is performed on the fat and oil concentrate prior to the aerobic treatment, so that compared to the case where the aerobic treatment is suddenly performed on the fat and oil concentrate. It is possible to effectively decompose oil and fat.

  Furthermore, when Example 3- (6) and Example 3- (7) are compared, by adding the sludge acclimatized in the biological treatment tank as an oil-decomposing microorganism during the preparation of the oil-and-fat concentrate, the oil-and-fat components are decomposed. The rate could be improved by 7% (see Table 3). That is, a further fat and oil decomposition effect by the fat and oil-degrading microorganisms was obtained in the biological treatment, and the treatment efficiency of the biological treatment on the concentrate after concentration and separation could be further increased.

  In addition, the comparison between Example 3- (7) and Comparative Example 3 shows that when the flocculant is changed from iron to PAC, the decomposition rate of the fat component decreases by 23%.

  Hereinafter, in the continuous biological treatment test carried out in the sections of Comparative Example 3 and Example 3- (7), the fat and oil concentrate collected from the anaerobic tank (anaerobic treatment means) among the biological treatment means is obtained by thin layer chromatography. Table 4 shows the results of the composition analysis.

  As shown in Table 4, in the comparative example, the proportion of triglycerol, which is an undecomposed oil component, in the total fat component is 46.9%, whereas in the examples, the proportion of triglycerol in the total fat component Was as low as 2.0%, indicating that hydrolysis was accelerated. Thus, it was shown that by using an iron salt as a flocculant to be used for concentration and separation of fats and oils, the hydrolysis of fats and oils in the biological treatment process is promoted and the decomposition rate of fats and oils is improved.

[Comparative Example 4]
A mixture of commercially available mayonnaise and margarine in a mass ratio of 1: 1 is used as an oil / fat raw material, and this is added to city water to adjust the hexane extractable substance to 500 mg / L. Assumed.

  Ferric chloride was added to the oil-containing wastewater (raw water) at a concentration of 1 mg / L in terms of iron, and biological treatment was performed as it was. That is, the comparative example 4 assumes the case where an iron salt is added only to the biological treatment process like patent document 2, without performing concentration separation of the fats and oils by throwing in an iron salt.

  As a biological treatment tank used for biological treatment, a 2 L reaction vessel is prepared, and reaction conditions are set to 37 ° C., pH 7.5 to 8.2, dissolved oxygen concentration 1.0 mg / L, and initial sludge concentration 5,000 mg / L. A batch treatment test of raw water was conducted.

  The results are shown in FIG. FIG. 6 is a diagram showing the results of a batch-type biological treatment test for fat-and-oil-containing wastewater (raw water) of Comparative Example 4. As shown in the figure, 68% of the fat and oil components contained at the start of the test 6 hours after the start of the test rapidly decompose, and then the decomposition rate of the fat and oil components is remarkably slowed, and the 84 hour treatment test ends. Thus, an oil and fat component corresponding to 10% of the initial charge remained. As described above, in the biological treatment of unconcentrated oil-containing wastewater (raw water), even when iron is added, the decomposition rate of the oil / fat component decreased from the middle to the latter half of the biological treatment.

  This is because, under aerobic biological treatment conditions, some of the fat components to be decomposed form a fat residue due to aerobic treatment (aeration treatment), It can be said that it remained without being decomposed even in the second half.

[Example 4]
A mixture of commercially available mayonnaise and margarine in a mass ratio of 1: 1 is used as an oil and fat raw material, and this is added to city water to adjust the hexane extractant to 400 mg / L. Assumed.

  Add fat-decomposing microorganisms to this oil-containing wastewater (raw water) at a concentration of 200 mg-SS / L, and add ferric chloride to 400 mg / L in terms of iron, then concentrate and separate it 40 times. Assuming that the product is obtained, the biological treatment tank sludge and ferric chloride obtained in the city water under the condition (4) of Example 2 are respectively converted into iron at 8,000-SS / L and 16,000 mg. The oil / fat concentrate was added to the oil / fat raw material so that the hexane extractant concentration was 16,000 mg / L.

  As biological treatment tanks, 0.6 L, 3.0 L, and 1.0 L reaction vessels are prepared, respectively, anaerobic tanks used for anaerobic treatment (anaerobic treatment means), and methane fermentation tanks used for decomposition treatment by methanogenic bacteria ( An aerobic tank (aerobic treatment means) used for one-stage aerobic treatment. The reaction conditions for the anaerobic tank are 45 ° C., pH 7.5 to 8.5, and the residence time is 96 hours. The reaction conditions for the methane fermentation tank are 55 ° C., pH 7.0 to 8.0, and the residence time is 360 hours. The reaction conditions of the aerobic tank were 50 to 55 ° C., pH 7.5 to 8.2, dissolved oxygen concentration 1.0 mg / L, and residence time 120 hours.

[Example 5]
A test similar to that of Example 4 was performed except that the anaerobic treatment was not performed.

  That is, 3.0 L and 1.0 L reaction vessels were prepared as biological treatment tanks, and each was in turn a methane fermentation tank (decomposition treatment means) and an aerobic tank (aerobic treatment means) used for one-stage aerobic treatment. . The reaction conditions of the methane fermenter are set to 55 ° C., pH 7.0 to 8.0, residence time 456 hours, the reaction conditions of the aerobic tank are 50 to 55 ° C., pH 7.5 to 8.2, dissolved oxygen concentration 1 The oil and fat concentrate was subjected to a continuous treatment test at a setting of 0.0 mg / L and a residence time of 120 hours.

  The reason why the residence time of the methane fermentation tank is set to 456 hours is to match the entire biological treatment time with the conditions of Example 4. Other conditions were the same as in Example 4.

[Comparative Example 5]
The same test as in Example 4 was performed except that PAC was used instead of ferric chloride.

  That is, the biological treatment tank sludge obtained under the condition (4) of Example 2 was added to city water at a concentration of 8,000-SS / L, and PAC was added at a concentration of 16,000 mg / L on a product basis. And what added the said oil-and-fat raw material so that a hexane extract substance density | concentration might be 16,000 mg / L was used for the test as a concentrate of fat and oil. Other conditions were the same as in Example 4.

  In Examples 4 to 5 and Comparative Example 5, after the quality of treated water is stabilized, anaerobic treated water after anaerobic treatment, decomposed treated water after degradation by methanogen, and biologically treated water after aerobic treatment The hexane extractable substance concentration was measured, and the decomposition rate (n-Hex decomposition rate) of the hexane extractant was calculated.

  Table 5 shows test conditions of Examples 4 to 5 and Comparative Example 5, and Table 6 shows results of continuous treatment tests of Examples 4 to 5 and Comparative Example 5.

※14：実施例２の条件（４）で得られた生物処理槽の汚泥を示す。

* 14: Indicates the sludge of the biological treatment tank obtained under the condition (4) in Example 2.

※15：油脂含有排水（原水）ｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）と嫌気処理水、分解処理水、生物処理水のそれぞれのｎ−Ｈｅｘ濃度（ｍｇ／Ｌ）を４０で除した値との差分から算出されるヘキサン抽出物質の分解率を示す。
※16：ＰＡＣ等の従来の無機凝集剤で回収した油脂濃縮物において、油脂成分が密に固まった粒状物を形成し、生物処理における反応性が著しく低下する結果、そのまま粒状物の形状で処理水に分散した状態をいう。

* 15: Oil and fat-containing wastewater (raw water) n-Hex concentration (mg / L) and the value obtained by dividing the n-Hex concentration (mg / L) of anaerobic treated water, decomposed treated water, and biological treated water by 40 The decomposition rate of the hexane extract substance calculated from the difference is shown.
* 16: Fat concentrate collected with a conventional inorganic flocculant such as PAC forms a granular product in which the fat and oil components are tightly solidified, resulting in a significant decrease in the reactivity in biological treatment. A state dispersed in water.

  As shown in Example 4 of Table 5 and Table 6, an anaerobic treatment as a biological treatment and a concentrate obtained by adding an oil-degrading microorganism and an iron salt to an oil-containing wastewater (raw water) and When the methane fermentation treatment (decomposition treatment) was performed during the aerobic treatment, the biologically treated water after the aerobic treatment showed a high decomposition rate of 95% of the hexane extract.

  Moreover, as shown in Example 5, even when a methane fermentation process (decomposition process) is introduced into the biological process, the decomposition rate of the hexane extract substance of the biologically treated water is 76 when the anaerobic process is not performed. %, Which is lower than that of Example 4.

  Further, when conventional anaerobic digestion (decomposition treatment with methane-producing bacteria) and aerobic treatment were performed without anaerobic treatment, symptoms of anaerobic digestion inhibition were observed.

  In addition, as shown in Comparative Example 5, even when the conventional anaerobic digestion (decomposition treatment with methanogen) is performed in addition to the anaerobic treatment, the biological treatment is performed when the iron salt is not added. The decomposition rate of the hexane extractant in water remained 70%, which was lower than in Example 4. Furthermore, in Comparative Example 5 in which PAC was added instead of Fe as a flocculant, the dispersion of fats and oils in biologically treated water was worse than that in Example 4.

DESCRIPTION OF SYMBOLS 1 Fat and oil containing wastewater 2 Iron salt 4 Oil and fat decomposition preparation 6 Oil and fat decomposing microorganisms 10, 70 Oil and fat containing wastewater treatment equipment 15 Supply means 20 Input / concentration separation means 22 Concentrate 24 Concentration separation tank (concentration separation means)
26 Input means 30, 80 Biological treatment means 34 Anaerobic tank (anaerobic treatment means)
38, 62 Aerobic tank (aerobic treatment means)
50 Activated sludge treatment means (aerobic treatment means)
74 Biological treatment tank (biological treatment means)
82 Methane fermenter (decomposition treatment means)

Claims (8)

  A method for treating fat and oil-containing wastewater, comprising subjecting an oil-containing wastewater to an iron salt to concentrate and separate the oil and fat, and subjecting the concentrate obtained by the concentration and separation treatment to biological treatment. The biological treatment is
At least one of degradation, emulsification and dispersion by at least one microorganism selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria in an anaerobic environment or a microaerobic environment The treatment method of the fat-and-oils containing wastewater of Claim 1 characterized by including the anaerobic process which is a process which makes one effect | action, and the aerobic process given to the processed material obtained by this anaerobic process . The biological treatment is
Between the anaerobic treatment and the aerobic treatment, including a decomposition treatment in which a treatment product obtained by the anaerobic treatment is subjected to a decomposition treatment by methanogens,
The method for treating fat and oil-containing wastewater according to claim 2, wherein the aerobic treatment is performed on the decomposition product obtained by the decomposition treatment.   Prior to the biological treatment, at least one of the fat-containing wastewater and the concentrate is supplied with an oil-degrading preparation and / or an oil-degrading microorganism. The processing method of the fat-and-oil containing waste water as described in any one of. A processing apparatus for oil-containing wastewater,
Input / concentration separation means for applying an iron / salt to fat / oil containing wastewater to concentrate and separate the oil / fat, and biological treatment means for applying biological treatment to the concentrate obtained by the concentration / separation process An apparatus for treating oil-containing wastewater, comprising: The biological treatment means is
At least one of degradation, emulsification and dispersion by at least one microorganism selected from the group consisting of anaerobic bacteria, facultative anaerobic bacteria, microaerobic bacteria and aerobic bacteria in an anaerobic environment or a microaerobic environment Anaerobic processing means for applying anaerobic processing, which is a process that causes two actions, and an aerobic processing means for applying an aerobic treatment to a processed product obtained by the anaerobic processing. The processing apparatus of the fat-and-oil containing waste water of Claim 5. Including a decomposition treatment means for performing a decomposition treatment with a methanogen on the processed product obtained by the anaerobic treatment,
The fat and oil-containing wastewater treatment apparatus according to claim 6, wherein the aerobic treatment means is an aerobic treatment means for performing an aerobic treatment on the decomposed product obtained by the decomposition treatment.   Prior to the biological treatment, at least one of the oil-containing wastewater and the concentrate has supply means for supplying an oil-degrading preparation and / or an oil-decomposing microorganism. The processing apparatus of the fat-and-oil containing waste water of any one of these.

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