JP2012192339A - Method and apparatus for treating wastewater containing organic matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the oxidative decomposition capacity of organic matter contained in wastewater by activated sludge.SOLUTION: A method for treating wastewater containing organic matter includes steps of: adding and mixing galacto-oligosaccharide and wastewater containing organic matter into activated sludge containing aerobic microorganisms; performing aeration treatment to an obtained mixture to oxidatively decompose the organic matter contained in the wastewater by the aerobic microorganisms; separating the oxidatively decomposed mixture into a sludge part and a treated wastewater part; and etc. An apparatus for treating wastewater containing organic matter includes an activated sludge treatment tank (21) for storing activated sludge containing aerobic microorganisms; a means for supplying the activated sludge treatment tank with galacto-oligosaccharide and wastewater containing organic matter; a means (24) for aerating the activated sludge treatment tank to oxidatively decompose the organic matter contained in the wastewater by the aerobic microorganisms; a means (22) for separating the oxidatively decomposed mixture into the sludge part and the treated wastewater part; and etc.

Description

  The present invention relates to a method for treating organic matter-containing wastewater by activated sludge and an apparatus for treating organic matter-containing wastewater by activated sludge using the sludge activation action of galactooligosaccharides.

  Conventionally, as a method of treating wastewater containing a large amount of organic matter, such as sewage treatment and industrial wastewater treatment, activated sludge containing aerobic microorganisms has an action of oxidizing and decomposing organic matter, that is, oxygen is oxidized using oxygen as an oxidizing agent. An activated sludge treatment method utilizing the action of decomposing to carbon has been widely used. The wastewater treatment method introduces wastewater containing a large amount of organic substances into an activated sludge treatment tank in which activated sludge containing aerobic microorganisms is stored, and aerobic microorganisms in activated sludge are propagated while introducing air and aeration. By doing so, the organic matter in the wastewater is oxidatively decomposed.

  However, the conventional activated sludge treatment methods are mainly composed of a blower and an air diffuser to promote oxidative degradation and to stir the activated sludge treatment tank to prevent oxidative degradation failure due to sedimentation of the activated sludge. There is a problem that it is necessary to always supply air by the aeration apparatus, and the power consumption by the continuous operation of the aeration apparatus becomes large. In addition, when the organic matter in the wastewater is oxidatively decomposed, accompanied by the growth of activated sludge, in order to maintain stable activated sludge treatment, it is necessary to discharge the surplus activated activated sludge from the activated sludge treatment tank, Since the discharged activated sludge that has been discharged needs to be disposed of as waste, there has been a problem that the treatment cost and the burden on the environment are increased. Furthermore, the activated sludge treatment facility requires an activated sludge treatment tank and a sedimentation tank for separating the treated water and activated sludge, and the required capacity of the tank depends on the oxidative decomposition efficiency by the activated sludge. However, the conventional activated sludge treatment method also has a problem that it requires a very large equipment area and equipment investment.

  As a solution for this, for example, in Patent Document 1, it is produced in a process of producing recovered pulp from waste paper raw materials containing thermal paper for the purpose of providing a method for effectively reducing COD of thermal waste paper recovered pulp production wastewater. There has been proposed a wastewater treatment method characterized in that activated sludge treatment is performed after a BOD component-containing substance is added to wastewater to make a BOD / COD ratio of 0.3 or more. This document also describes that the BOD component-containing substance contains at least one of polysaccharides, oligosaccharides, monosaccharides, proteins, and lower alcohols. Furthermore, the document describes that organic substances are adsorbed on sludge, the adsorbed organic substances are oxidatively decomposed, and the inactivation of activated sludge is caused by the adsorption of excessive persistent substances, Further, it is described that it is desirable to reduce the COD adsorption rate by increasing the ratio of the BOD component-containing substance to be added and increasing the BOD / COD ratio.

  However, in such prior art, the target wastewater is limited to heat-sensitive waste paper recovered pulp production wastewater, and other organic matter-containing wastewater is not specified. In addition, the purpose is to suppress adsorption of hardly decomposable substances to activated sludge, and it does not solve the conventional problems.

Japanese Patent Laid-Open No. 04-271897

  The present invention has been made in view of such conventional problems, and in particular, by adding galactooligosaccharide to activated sludge, the ability to oxidatively decompose organic substances contained in wastewater by aerobic microorganisms in activated sludge. It is intended to improve and solve the problem. That is, the present invention focuses on the fact that activated sludge is activated by galactooligosaccharide and the ability to oxidatively decompose organic substances contained in wastewater is improved. By improving the oxidative degradation ability of aerobic microorganisms in the activated sludge, the amount of activated sludge required for oxidative degradation of organic matter can be reduced as a result, and as a result, air for aeration, etc. Reduce the amount of oxygen source and power consumption for agitation, and further reduce the amount of surplus activated sludge discharged to reduce waste treatment costs, downsize the entire activated sludge treatment facility, It is intended to enable the reduction of capital investment to be achieved.

  The present invention is based on the finding that galactooligosaccharides, in particular, activate activated sludge and improve the ability to oxidatively decompose organic matter in activated sludge.

  The treatment method for organic matter-containing wastewater according to the first aspect of the present invention, as described in claim 1, includes a step of adding and mixing galactooligosaccharide and organic matter-containing wastewater to activated sludge containing aerobic microorganisms. A process of subjecting the mixture to aeration, oxidative decomposition of organic matter contained in the wastewater by aerobic microorganisms, a step of separating the oxidatively decomposed mixture into a sludge part and a treated wastewater part, and a process of discharging the treated wastewater part It is characterized by including.

  In the first aspect, it is possible to activate the aerobic microorganisms in the activated sludge with galactooligosaccharides and improve the ability to oxidatively decompose organic substances contained in the wastewater. In addition, by improving the oxidative degradation ability of such aerobic microorganisms, the concentration of suspended solids (MLSS: Mixed Liquor Suspended Solids) in the mixed liquid subjected to oxidative decomposition treatment (activated sludge treatment) is reduced, that is, in the activated sludge treatment mixed liquid. It is possible to reduce the activated sludge concentration. By reducing the activated sludge concentration in the activated sludge treatment mixture, the amount of air for aeration and the power consumption of agitation are reduced, and the amount of excess sludge discharged and the environmental burden and costs associated with disposal of waste are reduced. Can be reduced. Further, the method for treating organic matter-containing wastewater in this aspect can be advantageously applied to, for example, sewage treatment plants, septic tanks, and industrial organic matter-containing wastewater treatment facilities.

  One preferred embodiment of the first aspect is a method for treating organic matter-containing wastewater, wherein galactooligosaccharide is added in an arbitrary amount with respect to the amount of dry matter sludge in the activated sludge treatment tank. Preferably, the galactooligosaccharide is activated. Addition of organic matter-containing wastewater added at a rate of 400 g / (ton (DS) · day) to 4,000 g / (ton (DS) · day) with respect to the amount of dry matter sludge (DS) in the sludge treatment tank And a processing method (see claim 2). According to this form, the activated sludge in the activated sludge treatment tank can be activated.

  As another preferred form of the first aspect, the treatment of organic matter-containing wastewater is a step in which the separation step is a step of subjecting the mixture subjected to oxidative decomposition to sedimentation to separate into a settled sludge portion and a supernatant treatment wastewater portion. A method (see claim 3). According to this form, it is possible to discharge the settled sludge and to discharge the treated drainage section.

  As another preferred embodiment of the first aspect, a step of recirculating at least a part of the sludge portion separated by the separation step to the mixing step, and a step of discharging a part of the sludge portion as necessary. Furthermore, the processing method of the organic matter containing waste_water | drain containing is mentioned (refer Claim 4). According to this form, it is possible to maintain the suspended solid concentration (MLSS: Mixed Liquor Suspended Solids) in the activated sludge treatment tank.

  The organic matter-containing wastewater treatment apparatus according to the second aspect of the present invention includes an activated sludge treatment tank (21) for storing activated sludge containing aerobic microorganisms, and a galactooligo in the activated sludge treatment tank. Means for supplying sugar and organic matter-containing wastewater, means for aeration of the organic matter contained in the wastewater by aerobic microorganisms into the activated sludge treatment tank (24), treatment of the oxidatively decomposed mixture with the sludge section A means (22) for separating into a drainage part and a means (30) for discharging the treated drainage part are included.

  In the second aspect, it is possible to activate the aerobic microorganisms in the activated sludge in the activated sludge treatment tank with the galactooligosaccharide and improve the ability to oxidize and decompose organic substances contained in the wastewater. In addition, by improving the oxidative degradation ability of aerobic microorganisms, the concentration of suspended solids (MLSS: Mixed Liquor Suspended Solids) in the mixed liquid that has been subjected to oxidative degradation treatment (activated sludge treatment) in the activated sludge treatment tank, that is, activated sludge The activated sludge concentration in the treatment liquid mixture can be reduced. By reducing the concentration of activated sludge in the activated sludge treatment mixture, the amount of air used for aeration in the activated sludge treatment tank and the power consumption of stirring are reduced, the amount of excess sludge discharged and the environment associated with disposal of waste It is possible to reduce the load and cost of the apparatus, reduce the size of the organic substance-containing wastewater treatment apparatus, and reduce the installation space. The organic matter-containing wastewater treatment apparatus in this aspect can be advantageously applied to, for example, a sewage treatment plant, a septic tank, and an industrial organic matter-containing wastewater treatment facility.

  As one preferred form of the second aspect, means for adjusting the amount of galactooligosaccharide supplied to the supply means to an arbitrary amount with respect to the amount of dry matter sludge in the activated sludge treatment tank, preferably galactooligosaccharide is activated An organic matter-containing wastewater treatment apparatus further comprising means for adjusting the amount of dry matter sludge in the sludge treatment tank to a rate of 400 g / (ton (DS) · day) to 4,000 g / (ton (DS) · day). (Refer to claim 6). According to this form, the activated sludge in the activated sludge treatment tank can be activated.

  As another preferred form of the second aspect, the organic substance is a settling tank in which the separation means (22) separates the mixture that has undergone oxidative decomposition into a settled sludge section and a supernatant treated drainage section. An apparatus for treating the contained wastewater is mentioned (see claim 7). According to this form, it is possible to discharge the settled sludge and to discharge the treated drainage section.

  As another preferred form of the second aspect, means (32) for recirculating at least a part of the sludge section formed in the separating means (22) to the activated sludge treatment tank, and, if necessary, the sludge section. An organic matter-containing wastewater treatment apparatus further comprising means (31) for discharging a part of the wastewater (see claim 8). According to this form, it is possible to maintain the suspended solid concentration (MLSS: Mixed Liquor Suspended Solids) in the activated sludge treatment tank.

It is explanatory drawing which shows typically the activated sludge processing apparatus of the conventional organic substance containing waste_water | drain. It is explanatory drawing which shows typically an example of the activated sludge processing apparatus of the organic substance containing waste_water | drain in this invention. It is explanatory drawing which shows the time-dependent change of MLSS in the activated sludge process of the organic substance containing waste_water | drain of this invention. It is explanatory drawing which shows a time-dependent change of the COD removal rate in the activated sludge process of the organic substance containing waste_water | drain of this invention.

  The organic matter-containing wastewater in the method or apparatus for treating organic matter-containing wastewater of the present invention is not particularly limited. For example, domestic wastewater, cereal starch manufacturing industry, dairy manufacturing industry, meat center, sugar manufacturing industry, livestock production Sewage and industrial wastewater from food manufacturing industry, livestock agriculture, meat product manufacturing industry, meat ham and sausage manufacturing industry, fishery paste product manufacturing industry, fishery food product manufacturing industry, manufacturing industry such as organic chemical industry and inorganic chemical industry, etc. Waste water. That is, the organic substance-containing wastewater treatment method and treatment apparatus of the present invention are advantageously applied to sewage treatment plants, septic tanks, industrial organic matter-containing wastewater treatment facilities, and the like.

  The activated sludge containing aerobic microorganisms in the method or apparatus for treating organic matter-containing wastewater of the present invention is not particularly limited as long as it contains aerobic microorganisms that can be used for organic matter-containing wastewater treatment, For example, there are activated sludges containing aerobic microorganisms such as Vorticella for protozoa and Philodina (rotifers) for minute metazoans.

The galactooligosaccharide in the method or apparatus for treating organic matter-containing wastewater of the present invention is an oligosaccharide having galactose as a main constituent unit as shown in the following structural formula, and is a by-product when, for example, cheese is produced from milk. It is manufactured by causing an enzyme to act on certain lactose.

  In the method for treating organic matter-containing wastewater of the present invention, as a step of adding and mixing galactooligosaccharide and organic matter-containing wastewater to activated sludge containing aerobic microorganisms, there is no particular limitation on the form and order of addition, for example, Organic wastewater and galactooligosaccharide may be added to and mixed with activated sludge, galactooligosaccharide may be added while adding and mixing organic matter-containing wastewater to activated sludge, or organic matter-containing wastewater is added to activated sludge. After adding and mixing, galactooligosaccharide may be added and mixed. Further, the treatment method of the organic matter-containing wastewater of the present invention may be a batch type or a continuous type, and in the case of treating a large amount of organic matter-containing wastewater, the continuous method is preferable. It is desirable to mix galactooligosaccharides together or separately while adding them to the activated sludge.

  The amount of galactooligosaccharide added varies depending on the type and concentration of organic matter in the organic wastewater and the amount of activated sludge. The activated sludge treatment tank is used for the purpose of activating activated sludge. It is preferable to make the addition amount according to the number of activated sludge in the inside, and the addition amount according to the dry sludge amount (DS: Dry Sludge) in the activated sludge treatment tank is preferred. Usually added in any amount to dry matter sludge in the activated sludge treatment tank so that the organic matter contained in the wastewater can be efficiently oxidized and decomposed while improving the activity of aerobic microorganisms in the activated sludge. However, a ratio of 400 g / (ton (DS) · day) to 4,000 g / (ton (DS) · day) is particularly preferable. The amount of organic matter-containing wastewater relative to the amount of activated sludge can be appropriately determined so that the organic matter contained in the wastewater can be efficiently oxidatively decomposed while improving the activity of aerobic microorganisms in the activated sludge. Is.

  In the method for treating organic matter-containing wastewater of the present invention, it is used for aeration in the step of subjecting the mixture of activated sludge, galactooligosaccharide and organic matter-containing wastewater to aeration and oxidative decomposition of organic matter contained in the wastewater by aerobic microorganisms. As the gas, air is usually used. Further, as a form of introducing a gas such as air during aeration, blowing of the mixture into the inside is usually used. However, in some cases, blowing of gas while stirring may be used. The amount of gas such as air to be introduced can be appropriately determined so that galactooligosaccharides can efficiently oxidize and decompose organic substances contained in wastewater while improving the activity of aerobic microorganisms in activated sludge. As the range, the dissolved oxygen (DO) in the activated sludge treatment tank is preferably 1.0 mg / L or more.

  By the aeration process and oxidative decomposition process, the organic matter in the organic matter-containing wastewater is usually decomposed and the activated sludge is flocked by the viscous substance discharged from the aerobic microorganism.

  The suspended solids concentration (MLSS: Mixed Liquor Suspended Solids) in the mixture subjected to oxidative decomposition treatment (activated sludge treatment) is 1,500 mg / L to 2,000 mg / L in the standard activated sludge method, and it is a long-term aeration method. Then, it is 3,000 mg / L to 5,000 mg / L. Thus, by improving the activity of aerobic microorganisms in activated sludge with galactooligosaccharide, the suspended solids concentration (MLSS) in the mixture subjected to oxidative degradation treatment (activated sludge treatment) is reduced, that is, the activated sludge treatment mixture. Reduction of the activated sludge concentration inside can be expected.

  As other conditions in the process of aeration and oxidative degradation, the galactooligosaccharide can improve the activity of aerobic microorganisms in the activated sludge, and the organic matter contained in the wastewater can be efficiently oxidatively decomposed. The temperature is preferably higher, and the time (average residence time in the case of continuous type) is preferably 6 to 8 hours in the standard activated sludge method, and 18 to 24 hours in the long-time aeration method. The pressure is usually preferably atmospheric pressure. By improving the activity of aerobic microorganisms in the activated sludge with galactooligosaccharide, the treatment time can be shortened.

  In the method for treating organic matter-containing wastewater according to the present invention, as a step of separating the oxidatively decomposed mixed liquid into a sludge part and a treated wastewater part, a mixture containing activated flocs and the like flocked generated by oxidative decomposition is used. However, there is no particular limitation as long as it can be separated into a sludge section containing activated floc and sludge and a treatment drainage section. For example, sedimentation separation, pressure flotation method, etc. can be mentioned. Precipitation separation that does not require is preferably used. In the sedimentation separation, the mixture that has been subjected to the oxidative decomposition treatment is separated into a sludge section containing activated sludge that has been flocked at the bottom of the sedimentation separation means, and a treated drainage section as the supernatant at the top. The conditions for the sedimentation separation can be appropriately set, and the water area load (rising flow rate) is preferably 1.0 m / hour or less.

  The step of discharging the treated drainage portion in the method for treating organic matter-containing wastewater of the present invention is not particularly limited, and a commonly used method is used.

  When the method for treating organic matter-containing wastewater of the present invention is carried out continuously, sludge containing activated sludge that has been flocked, separated by a step of separating the mixture subjected to oxidative decomposition into a sludge portion and a treated wastewater portion It is desirable to recycle at least part of the part to the process of mixing activated sludge, galactooligosaccharide and organic matter-containing wastewater, and if necessary, activated flocated sludge generated by activated sludge treatment of organic matter-containing wastewater. It is also desirable to discharge a part of the sludge portion in order to remove surplus activated sludge containing slag.

  The ratio between the amount of sludge discharged and the amount of sludge recirculated is that the organic matter contained in the wastewater is efficiently oxidized while improving the activity of aerobic microorganisms in the activated sludge by galactooligosaccharide. Although it can set suitably so that it can maintain that it decomposes | disassembles, it is preferable to set so that the suspended | floating matter density | concentration (MLSS: Mixed Liquor Suspended Solids) in an activated sludge processing tank may become fixed. By improving the activity of aerobic microorganisms in activated sludge with galactooligosaccharides, it can be expected to reduce the concentration of suspended solids in the activated sludge treatment tank. The environmental burden and cost can be reduced. It can be expected to reduce the environmental burden and costs associated with waste disposal.

  The activated sludge treatment tank for storing activated sludge containing aerobic microorganisms in the organic matter-containing wastewater treatment apparatus of the present invention is not particularly limited and may be a normally used activated sludge treatment tank.

  The means for supplying galactooligosaccharide and organic matter-containing wastewater to the activated sludge treatment tank in the organic matter-containing wastewater treatment apparatus of the present invention is not particularly limited, and may be a normally used activated sludge treatment tank. For example, the galactooligosaccharide and the organic matter-containing waste water may be supplied together or separately to the activated sludge treatment tank.

  In the processing apparatus for organic matter-containing wastewater of the present invention, the means for aeration of the organic matter contained in the wastewater by aerobic microorganisms to the activated sludge treatment tank includes activated sludge and galactooligosaccharides in the activated sludge treatment tank. In addition, there is no particular limitation as long as organic wastewater containing organic substances is mixed and oxygen can be supplied into the mixture in a predetermined amount. For example, air blowing for blowing aeration air from the lower part of the activated sludge treatment tank Examples thereof include a pipe and / or a stirrer of the mixture in the activated sludge treatment tank.

  In the organic matter-containing wastewater treatment apparatus of the present invention, as a means for separating the mixture after the oxidative decomposition treatment into the sludge portion and the treated wastewater portion, the sludge portion containing the activated sludge and the treated wastewater portion are effective. The separation tank is not particularly limited as long as it can be separated, and examples thereof include a precipitation tank and a pressure levitation device. Usually, a precipitation tank that does not require special processing energy is preferably used. In the settling tank, the oxidative decomposition-treated mixture is separated into a sludge section containing activated flocs in the lower part of the settling tank and a treated drainage section as an upper supernatant.

  The means for discharging the treated drainage portion in the organic matter-containing wastewater treatment apparatus of the present invention is not particularly limited, for example, a pipe that is provided on the upper wall of the settling tank and flows out as a supernatant of the treated drainage portion, etc. Is mentioned.

  In addition, in the case where the organic matter-containing wastewater treatment apparatus of the present invention continuously performs activated sludge treatment, at least a part of the sludge portion containing activated fludge that is flocked and formed by a separating means such as a sedimentation tank is used. It is desirable to further include means for recirculating the wastewater to the activated sludge treatment tank and, if necessary, means for discharging a part of the sludge portion containing the activated sludge that has been flocked. The recirculation means and the discharge means of the sludge part are not particularly limited as long as each can recirculate or discharge a predetermined amount of sludge part. For example, a pump capable of setting the flow rate of each sludge part and What consists of piping is mentioned.

  Below, the embodiment which actualized the processing device of the organic matter content drainage of the present invention is described further, referring to drawings. In addition, the code | symbol described in said parenthesis is an example which shows a corresponding relationship with the specific description in embodiment mentioned later.

  FIG. 1 schematically shows a conventional activated sludge treatment apparatus for organic matter-containing wastewater. The activated sludge treatment apparatus there comprises an activated sludge treatment tank 1 and a settling tank 2. The activated sludge treatment tank 1 in which the activated sludge 15 is stored together with the water 7 is supplied with organic matter-containing wastewater containing the organic matter 14 from the pipe 6, and air is supplied from the air blowing diffuser pipe 4 connected to the blower 3. Bubbles 13 are blown. Together with the aeration by the bubbles 13, the organic matter 14 is oxidatively decomposed by the activated sludge 15 containing aerobic microorganisms, and a flocked activated sludge 16 is generated. The sludge portion containing the activated sludge 16 that has been flocked and that has been oxidized and decomposed is introduced into the settling tank 2 through the pipe 8 and flocked by sedimentation. And the treated drainage section as the supernatant 9. The treated drainage section as the supernatant 9 is discharged through the pipe 10. On the other hand, a part of the sludge portion including the activated sludge 16 that has been flocked is discharged as excess sludge through the pipe 11 by the pump 5, and the remaining sludge portion is returned to the activated sludge treatment tank 1 via the pipe 12. Is recycled.

  FIG. 2 schematically shows an example of an activated sludge treatment apparatus for organic matter-containing wastewater in the present invention. The activated sludge treatment apparatus there comprises an activated sludge treatment tank 21 and a settling tank 22. The activated sludge treatment tank 21 in which the activated sludge 35 is stored together with the water 27 is charged with the galactooligosaccharide by the charging means 20, and the organic substance-containing wastewater containing the organic substance 34 is supplied from the pipe 26 and connected to the blower 23. The air bubbles 33 are blown from the diffuser 24 for blowing air. By aeration with bubbles 33 in the presence of galactooligosaccharide, activated sludge is activated, and organic matter 34 is oxidized and decomposed by activated sludge 35 containing aerobic microorganisms, resulting in flocked activated sludge 36. . The oxidatively decomposed mixture containing the flocked activated sludge 36 thus generated is introduced into the settling tank 22 via the pipe 28, and the sludge containing the flocked activated sludge 36 by sedimentation separation. And a treated drainage section as the supernatant 29. The treated drainage portion as the supernatant 29 is discharged through the pipe 30. On the other hand, a part of the sludge portion including the activated sludge 36 that has been flocked is discharged as excess sludge by the pump 25 via the pipe 31, and the remaining sludge portion is returned to the activated sludge treatment tank 21 via the pipe 32. Is recycled.

  FIG. 3 shows the change with time of MLSS in the activated sludge treatment of the organic matter-containing wastewater of the present invention. That is, galactooligosaccharides were added by the organic matter-containing wastewater treatment apparatus of the present invention as shown in FIG. 2 together with the control in which the activated sludge treatment was performed by the conventional organic matter-containing wastewater treatment equipment as shown in FIG. The time-dependent change of MLSS when an activated sludge process is made | formed is shown.

  FIG. 4 shows the change over time of the COD removal rate in the activated sludge treatment of the organic matter-containing wastewater of the present invention. That is, galactooligosaccharides were added by the organic matter-containing wastewater treatment apparatus of the present invention as shown in FIG. 2 together with the control in which the activated sludge treatment was performed by the conventional organic matter-containing wastewater treatment equipment as shown in FIG. The time-dependent change of the COD removal rate when the activated sludge treatment is performed is shown.

  “MLSS (mg / L)” also described in the examples described later is the suspended solids concentration (Mixed Liquor Suspended Solids) in the mixed solution that has been subjected to the oxidative decomposition treatment (activated sludge treatment) in the activated sludge treatment tank, That is, it means the activated sludge concentration in the activated sludge treatment mixture, which is obtained by an MLSS meter using light transmittance or ultrasonic strength. In the standard activated sludge method, MLSS is 1,500 mg / L. ˜2,000 mg / L, MLSS is 3,000 mg / L to 5,000 mg / L in the long-time aeration method.

  In addition, “COD removal rate (%)” described in Examples described later indicates how much the COD before wastewater treatment can be removed by wastewater treatment, and the expression [{1- (drainage COD after treatment / COD before wastewater treatment)} × 100]. Although there are a plurality of methods for measuring COD, there is a method for obtaining the oxygen demand by potassium permanganate at 100 ° C. using silver sulfate as a catalyst.

  Examples of the present invention will be described below more specifically with reference to examples of the present invention. However, the present invention is not limited to these examples. In addition, unless otherwise indicated, the quantity of each component in a following example and a comparative example is represented by "weight part."

Example 1
Using an organic matter-containing wastewater treatment apparatus as shown in FIG. 2, 52 L of activated sludge containing nitrifying bacteria as an aerobic microorganism (initial activated sludge concentration 2,498 mg / L) is charged into the activated sludge treatment tank 21. Add organic matter-containing wastewater at 6 L / hour and add galactooligosaccharide at 400 g / (ton (DS) · day), and blow air from the blower 23 through the air diffuser 24 for blowing dissolved oxygen in the activated sludge treatment tank (DO : Activated sludge treatment by oxidizing and decomposing organic matter components in wastewater containing organic matter continuously while aeration at room temperature under atmospheric pressure by blowing so that Dissolved Oxygen) is 1.0 mg / L or more. . The mixture that has been subjected to the oxidative decomposition treatment in the activated sludge treatment tank 21 is introduced into the settling tank 22 at 6 L / hour via the pipe 28, and the sludge portion containing the activated sludge 36 that has been flocked by sedimentation and the supernatant 29 Separated into a treated wastewater section. The treated drainage section as the supernatant 29 was discharged at 6 L / hour through the pipe 30. On the other hand, the sludge portion including the activated sludge 36 that has been flocked is periodically discharged by the pump 25 as surplus sludge through the pipe 31 and the remaining sludge portion is discharged at 3 L / hour via the pipe 32. And returned to the activated sludge treatment tank 21 for recirculation. The average residence time of the organic substance-containing wastewater in the activated sludge treatment tank 21 is 8.6 hours, and the average water area load (upflow rate) in the sedimentation tank 22 of the mixture subjected to the oxidative decomposition treatment is 0.45 m. / Hour.

  Such continuous activated sludge treatment was performed for 28 days, sampling was performed at the start, 7th, 14th, 21st and 28th days to measure MLSS and COD removal rate. The obtained MLSS and COD removal rate are shown in FIGS. 3 and 4 as changes with time.

Example 2
A continuous activated sludge treatment was performed for 28 days in the same manner as in Example 1 except that galactooligosaccharide was added at 4,000 g / (ton (DS) · day). Sampling was performed on the 21st and 28th days to measure the MLSS and COD removal rate. The obtained MLSS and COD removal rate are shown in FIGS. 3 and 4 as changes with time.

Comparative Example 1
Except that galactooligosaccharide is not added, the activated sludge treatment of the continuous type is performed for 28 days in the same manner as in Example 1, and sampling is performed on the initial, 7th, 14th, 21st, and 28th days. The COD removal rate was measured. The obtained MLSS and COD removal rate are shown in FIGS. 3 and 4 as changes with time.

  As shown in FIG. 3, by adding galactooligosaccharide, MLSS (Mixed Liquor Suspended Solids), that is, activity in the mixture subjected to oxidative decomposition treatment (activated sludge treatment) in the activated sludge treatment tank A reduction in the activated sludge concentration in the sludge treatment mixture was found. Further, as can be seen from FIG. 3, the reduction rate of MLSS at the end with respect to the start time is 6% (Comparative Example 1), 30% (Example 1), and 62% (Example 2). It has been found that the reduction rate of MLSS varies depending on the amount of galactooligosaccharide added. Therefore, in view of the reduction rate of MLSS, if the galactooligosaccharide is added in the range of 400 g / (ton (DS) · day) to 4,000 g / (ton (DS) · day), the amount added becomes larger. It is said that it is preferable.

  As shown in FIG. 4, by adding galactooligosaccharide, an increase in the COD removal rate in the initial stage from the start to 7 days is seen, but in the activated sludge treatment for a long period thereafter, the galactooligosaccharide It has been found that the addition has little effect on the COD removal rate.

  Accordingly, the degree of improvement in the oxidative degradation ability of organic matter by activated sludge obtained by the addition of galactooligosaccharide is related to the amount of galactooligosaccharide added, and ranges from 400 g / (ton (DS) · day) to 4,000 g / (ton). (DS) / day) If galactooligosaccharides are added, the higher the added amount, the higher the predetermined COD removal rate with lower MLSS, that is, the improvement of oxidative degradation ability can be expected. 3 and 4 can be read.

Claims (8)

Adding and mixing galactooligosaccharide and organic matter-containing wastewater to activated sludge containing aerobic microorganisms,
A process of subjecting the obtained mixture to aeration, and oxidative decomposition of organic substances contained in the wastewater by the aerobic microorganisms;
An organic matter-containing wastewater treatment method, comprising: separating the oxidatively decomposed mixture into a sludge portion and a treated wastewater portion; and discharging the treated wastewater portion.   The processing method of the organic matter containing wastewater of Claim 1 which adds the said galactooligosaccharide in arbitrary ratios with respect to the dry matter sludge amount in the process of carrying out the oxidative decomposition.   The treatment of organic matter-containing wastewater according to claim 1 or 2, wherein the separation step is a step of subjecting the mixture that has undergone the oxidative decomposition to sedimentation and separating the mixture into the sludge portion that has settled and the treatment wastewater portion of the supernatant. Method. The process of recirculating at least a part of the sludge part separated by the separation process to the mixing process, and further discharging the part of the sludge part as needed. The disposal method of the organic matter containing waste water as described in any one of Claims. An activated sludge treatment tank (21) for storing activated sludge containing aerobic microorganisms,
Means for supplying galactooligosaccharide and organic matter-containing wastewater to the activated sludge treatment tank;
Means (24) for aeration of the activated sludge treatment tank to oxidatively decompose organic substances contained in the wastewater by the aerobic microorganisms;
Means (22) for separating the oxidatively decomposed mixture into a sludge section and a treated drainage section, and means for discharging the treated drainage section (30)
Including organic matter-containing wastewater treatment equipment.   The treatment of organic matter-containing wastewater according to claim 5, further comprising means for adjusting the amount of the galactooligosaccharide supplied to the supply means to an arbitrary ratio with respect to the amount of dry matter sludge in the activated sludge treatment tank. apparatus.   The organic matter according to claim 5 or 6, wherein the separation means (22) is a settling tank that settles the oxidatively decomposed mixture and separates the settled sludge portion and the supernatant drainage portion. Wastewater treatment equipment. Means (32) for recirculating at least a part of the sludge portion formed by the separation means (22) to the activated sludge treatment tank, and means for discharging a part of the sludge portion (if necessary) ( 31)
The processing apparatus of the organic matter containing waste_water | drain as described in any one of Claims 5-7 further containing these.

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