TWI411584B - Method and apparatus for biologically treating organic matter-containing water - Google Patents

Abstract

A method and an apparatus for biological treatment of organic matter-containing water are provided to avoid an increase in the load with respect to a reverse osmosis membrane, prevent the contamination of the reverse osmosis membrane, and smoothly perform the water treatment using the reverse osmosis membrane. An apparatus(100) for biological treatment of organic matter-containing water comprises an anaerobic bioreactor(110), a membrane separation device(112), and a reverse osmosis membrane device(114). The anaerobic bioreactor performs methanogenesis by methanogenic bacteria when organic matter-containing water flows into the anaerobic bioreactor. The membrane separation device is connected to the anaerobic bioreactor. The membrane separation device separates treated liquid discharged from the anaerobic bioreactor. The reverse osmosis membrane device treats water separated by the membrane separation device.

Description

Biological treatment method and device for water containing organic matter

The present invention relates to a biological treatment method and apparatus for anaerobic treatment of water containing organic matter, and more particularly to a biological treatment of drainage for use as raw water for pure water production. Biological treatment method and device.

It is believed that the aerobic microbiota has a wide variety of organic matter decomposition capabilities compared to anaerobic microbial populations. Therefore, aerobic biological treatment using an aerobic microbial population is suitable for treating drainage (for example, food drainage) containing a complex polymer (polymer) compound. Further, since the hydrolysis rate of the high molecular organic substance is slow in the anaerobic biological treatment, it is usually necessary to set the hydraulic retention time to 30 days or more. In contrast, the standard hydraulic retention time of aerobic biological treatment is relatively short, about 0.5 days.

In recent years, water is recovered in equipment such as a semiconductor manufacturing plant that uses pure water and discharges the water, that is, biological treatment of the organic-containing wastewater, and the treated water is used as a raw material for pure water production. In the biological treatment of organic water-containing water thus subjected to such water recovery, aerobic biological treatment was previously employed. When the organic substance-containing water contains a nitrogen component, the nitrogen compound is oxidized under aerobic conditions to form nitric acid or nitrous acid, and denitrification is carried out under anaerobic conditions. In addition, in the case of aerobic biological treatment, the amount of microorganisms retained in the biological treatment tank is increased by immobilizing the aerobic microorganisms on the carrier, thereby increasing the processing speed (for example, Japanese Patent Laid-Open Publication No. Hei 9-187785) ). When a carrier is used, for example, the removal rate of organic matter in each biological treatment tank can be increased to about 1 kg-COD/m ³ /day to 2 kg-COD/m ³ /day.

When the treatment liquid obtained by such biological treatment is reused in pure water production, the treatment liquid is treated by a solid-liquid separation device to separate the microorganisms, and then the reverse osmosis membrane (RO membrane) separation device or the like is used. Desalination treatment (for example, Japanese Patent Laid-Open Publication No. 2007-175582).

As described above, when the raw water produced by using the drainage water as pure water is reused, the treatment using the membrane separation apparatus is usually performed. However, the separation membrane is clogged due to the operating conditions or the quality of the water to be treated. In particular, when the membrane is separated from the biological treatment liquid, the microorganism itself and the viscous substance generated by the microorganism adhere to the membrane surface. The tendency to block. The viscous substance produced by the microorganism has a hardly decomposable property mainly composed of a polymer organic substance, and the amount of production thereof increases substantially in proportion to the amount of microorganisms held in the biological treatment tank. Therefore, in the aerobic biological treatment using an aerobic microorganism having a large proliferation rate, the amount of the polymer organic substance produced is also large. In particular, when a biological treatment tank to which a carrier is added is used, the amount of microorganisms retained is increased, so that the amount of production of high molecular organic substances is increased.

On the other hand, the rate of proliferation of anaerobic microorganisms is slower than that of aerobic microorganisms, so the amount of formation of high molecular organic substances is relatively small. However, the anaerobic biological treatment originally has a slow decomposition rate of the organic matter, so that the organic matter contained in the treated water (the organic-containing water) is not easily decomposed, but is directly contained in or the decomposition intermediate is contained in the treatment. The phenomenon in the liquid. That is, when the aerobic biological treatment is performed, there is a possibility that the reverse osmosis membrane is contaminated by the microorganism product. On the other hand, when anaerobic biological treatment is performed, although the possibility of membrane fouling due to the production of microorganisms is low, the possibility of membrane fouling due to residual organic substances or decomposition intermediates in the treatment liquid becomes high. .

In addition, when the microorganisms contained in the treatment liquid are separated after biological treatment of the drainage, if the coagulation sedimentation or the pressurized floating method is used, the separation is not sufficient, and the separated water contains microorganisms, etc. Reverse osmosis membrane in the back stage of pollution. In particular, when a carrier is added to the biological treatment tank, it is necessary to use a sieve or the like in order to carry out solid-liquid separation of the carrier, but the particle size of the carrier which increases the surface area and increases the activity is small, so that the sieve is easily clogged, in order to avoid this phenomenon. It is necessary to use a solid-liquid separation device or a large sedimentation tank of a complicated structure.

On the other hand, when the biologically treated treatment liquid is subjected to solid-liquid separation by the immersion membrane provided in the biological treatment tank, the microorganisms and the like can be well separated, and thus the reverse osmosis membrane contamination in the subsequent stage can be prevented. However, there is a problem that the immersion film itself is clogged, and in particular, when the aerobic treatment is performed, there is a problem that the immersion film is clogged by the polymer organic matter generated by the microorganism, and the amount of permeated water is lowered.

Further, when the organic substance-containing water contains a nitrogen component, in the aerobic biological treatment for removing the nitrogen component, the organic nitrogen is inorganicized by the microorganism to generate ammonia, which is aerobic nitrifying bacteria ( Nitrifier) oxidizes to form nitrous acid or nitric acid, which lowers the pH of the liquid in the tank, so it is necessary to add a base for neutralization. Then, when the denitrification treatment of nitric acid is carried out under anaerobic conditions, nitric acid or nitrous acid is reduced to nitrogen by an anaerobic denitrifying bacteria, and a base is formed in the process to raise the pH. Therefore, it is necessary to add an acid for neutralization in the denitrification step. As described above, the acid or base added for neutralization during the biological treatment is a salt load of the reverse osmosis membrane (RO membrane) in the subsequent stage.

As described above, when the reaction is carried out until nitrous acid or nitric acid is formed and then denitrified, nitrous acid or nitric acid as a strong acid and OH ^- as a strong base are formed, and therefore it is necessary to neutralize a strong acid or a strong base. On the other hand, in the step of oxidizing the nitrogen compound, if the biological reaction is stopped at the time of ammonia production, only the ammonia which is weakly alkaline can be neutralized, and it is not necessary to neutralize the strong acid or the strong base. In order to stop the biological denitrification of the nitrogen compound at the stage of ammonia production, the nitrifying bacteria having a slower proliferation rate may not be propagated in the biological reaction tank. Specifically, if the residence time of the sludge in the biological reaction tank is shortened, the nitrifying bacteria are washed out from the biological reaction tank without being held in the tank, so that the reaction is stopped at the stage of ammonia formation.

However, in order to allow the nitrifying bacteria to flow out, the residence time of the sludge in the biological reaction tank must be set to 4 days or less. When the residence time of the sludge is reduced to about 4 days or less, the organic matter contained in the water to be treated is not sufficiently decomposed. Therefore, the biologically treated treatment liquid contains a large amount of residual organic matter, and in the reverse osmosis membrane device, the residual organic matter is used as a matrix to allow the microorganism to easily proliferate. The proliferating microorganisms cause clogging of the reverse osmosis membrane, thereby degrading the desalination performance of the reverse osmosis membrane.

As described above, when the organic substance-containing water is biologically treated and reused in pure water production, the drainage treatment process adversely affects the treatment using the reverse osmosis membrane. In addition, when the organic material-containing water is biologically treated and subjected to nitrification under aerobic conditions, the load on the reverse osmosis membrane device is increased by the addition of the neutralizing reagent, and the nitrogenation is shortened in order to suppress the progress of nitrification. The sludge retention time causes contamination of the reverse osmosis membrane due to residual organic matter. An object of the present invention is to provide an object for preventing the increase in the load on the reverse osmosis membrane when the treated water is reused as pure water for manufacturing water in the biological treatment of water containing organic substances, and also to prevent the increase in the load on the reverse osmosis membrane. The method and apparatus for treating the reverse osmosis membrane are smoothly carried out by contamination of the reverse osmosis membrane.

In order to solve the above-mentioned problems, the present invention solves the above problems by biologically treating water containing an organic substance under anaerobic conditions, and removing the organic substance in the water to be treated without performing the nitrification reaction, and removing the ammonium remaining in the treatment liquid after the biological treatment. The salt is concentrated in a reverse osmosis membrane unit and then treated separately. Further, the anaerobic biological treatment of organic matter is a step of producing an acid from an organic substance by an acid-producing microbial group, and a step of generating methane from an acid by a methanogen. The present inventors have found that a polymer organic substance which is a cause of membrane fouling is mainly produced by metabolism of an acid-producing flora associated with an acid generating step. Therefore, the inventors of the present invention have conceived that the above problems can be solved by generating methane without undergoing an acid generating step using an acid generating microbial group, thereby completing the present invention. In particular, the present invention provides the following methods and apparatus.

(1) A biological treatment method for water containing organic matter, which is treated in the following steps:

Introducing water containing organic matter into an anaerobic biological treatment tank;

Anaerobic biological treatment using the methane-producing flora in the anaerobic biological treatment tank;

The treatment liquid obtained by the above anaerobic biological treatment is subjected to membrane separation without aerobic biological treatment;

The separated water obtained by the above membrane separation was treated with a reverse osmosis membrane.

(2) The biological treatment method of the organic substance-containing water according to (1), wherein the ratio of the monomer organic substance to the total organic carbon in the organic substance-containing water is 70% or more.

(3) The biological treatment method of the organic-containing water according to (1) or (2), wherein the anaerobic treatment is performed by setting the temperature of the liquid in the tank to 15 ° C or more and 40 ° C or less.

(4) The biological treatment method of the organic substance-containing water according to (3), wherein the treatment liquid is heated in the anaerobic treatment process, and the treatment liquid is subjected to membrane separation and reverse osmosis membrane treatment.

(5) The biological treatment method of the organic-containing water according to (2), wherein the monomer organic substance is selected from the group consisting of tetramethylammonium hydroxide, monoethanolamine, diethylene glycol monobutyl ether, isopropanol, and Any one or more of the group consisting of methyl acetamide, dimethylformamide, dimethyl hydrazine, and acetic acid.

(6) A biological treatment device for water containing organic matter, comprising:

An anaerobic biological treatment tank, introducing water containing organic matter, and generating methane by using a methane-producing flora;

a membrane separation device connected to the anaerobic biological treatment tank to perform membrane separation on the treatment liquid discharged from the anaerobic biological treatment tank;

The reverse osmosis membrane device processes the separated water of the membrane separation device.

(7) The biological treatment apparatus of the organic substance-containing water according to (6), wherein the ratio of the monomer organic substance to the total organic carbon in the organic substance-containing water is 70% or more.

(8) The biological treatment apparatus for organic-containing water according to (6) or (7), which is configured as follows:

The anaerobic treatment tank is operated by setting the temperature of the liquid in the tank to 15 ° C or more and 40 ° C or less.

The treatment liquid is supplied to the membrane separation device and the reverse osmosis membrane device in a heated state in the anaerobic treatment tank.

(9) The biological treatment apparatus for organic-containing water according to (8), further comprising a heat recovery heating device for heat-recovering the permeated water of the reverse osmosis membrane device, and using the recovered heat to heat the anaerobic Sex processing tank.

(10) The biological treatment apparatus of the organic substance-containing water according to (6), wherein the membrane separation apparatus comprises a microfiltration membrane or an ultrafiltration membrane.

(11) The biological treatment apparatus for organic-containing water according to (6), further comprising a cleaning device for supplying bio-generated gas (biogas) generated in the anaerobic biological treatment tank to The membrane separation device performs aeration cleaning on the membrane separation device.

(12) A biological treatment device for water containing organic matter, comprising:

An anaerobic biological treatment tank for introducing water containing organic matter and generating methane by using a methane-producing flora;

a membrane separation device connected to the anaerobic biological treatment tank for membrane separation of the treatment liquid discharged from the anaerobic biological treatment tank;

a reverse osmosis membrane device for treating separated water of the membrane separation device;

The concentrated water treatment device treats the concentrated water of the reverse osmosis membrane device.

(13) The biological treatment apparatus of the organic substance-containing water according to (12), wherein the concentrated water treatment apparatus includes a biological treatment tank different from the anaerobic biological treatment tank.

(14) The biological treatment apparatus of the organic-containing water according to (12) or (13), wherein the concentrated water treatment apparatus includes an evaporator that introduces the concentrated water and evaporates the distilled water.

(15) The biological treatment apparatus of the organic substance-containing water according to (12), wherein the concentrated water treatment apparatus includes a reaction column, and a chemical capable of insolubilizing impurities in the concentrated water is added to the concentrated water. And separate the solids.

(16) A biological treatment method for water containing organic matter, comprising:

Anaerobic biological treatment is carried out by introducing water containing organic matter into an anaerobic biological treatment tank containing a methane-producing flora.

The treatment liquid obtained by the above anaerobic biological treatment is subjected to membrane separation without aerobic biological treatment.

Treating the separated water obtained by the above membrane separation with a reverse osmosis membrane,

The concentrated water obtained by the above reverse osmosis membrane treatment is treated.

(17) The biological treatment method of the organic-containing water according to (16), wherein the organic substance-containing water contains a nitrogen compound.

(18) The biological treatment method of the organic-containing water according to (16) or (17), wherein the concentrated water is subjected to biological treatment different from the anaerobic biological treatment; and the concentrated water is distilled by an evaporator Processing; and/or treating the concentrated water using chemicals to insolubilize the impurities.

In the present specification, the property of the water to be treated, that is, the water containing the organic substance is not particularly limited, and the organic carbon compound may contain not only the nitrogen compound. The term "total organic carbon" refers to a general term for various organic carbon compounds contained in water. It includes not only non-volatile organic substances, but also volatile organic compounds that cannot be measured by a conventional TOC (Total Organic Carbon) meter. Further, the organic carbon compound is preferably a ratio of a low molecular organic substance (hereinafter referred to as "monomer organic substance") which is directly absorbable by microorganisms (for example, 70% or more with respect to total organic carbon). The "monomer organic matter" is a general term for low molecular organic substances in which various microorganisms contained in the drainage are directly absorbed by microorganisms. Since the monomeric organic matter is decomposed by the methane-producing microflora, the organic acid-containing water mainly composed of the monomeric organic matter is difficult to proliferate in the step of anaerobic biological treatment. According to the knowledge of the inventors, when the proliferation of the acid-producing microbial group is inhibited, the formation of a polymer metabolite produced by the microorganisms can be suppressed, and the reverse osmosis membrane contamination by the metabolite can be prevented.

The "monomer organic substance" is an organic substance that cannot be decomposed by the extracellular enzyme through the microbial cell wall. Usually, the organic substance is polymerized with each other to have a large molecular weight. In the present specification, the use of "monomer organic matter" means The term "organic matter other than polymer organic matter". Specific examples of the monomeric organic substance include low molecular organic substances (for example, formic acid, acetic acid, methanol, methylamine, etc.) used as a matrix of the methane-producing microbial group, or tetramethylammonium hydroxide, monoethanolamine, and diethylene glycol alone. Butyl ether, isopropanol, dimethylacetamide, dimethylformamide, dimethyl alum. In the present invention, in particular, a compound having a methyl group as a monomeric organic substance (tetramethylammonium, dimethylacetamide, dimethylformamide, dimethylammonium) has a high content ratio. Organic water is a suitable treatment target.

In the present invention, the organic matter in the water to be treated is subjected to anaerobic biological treatment using a methane-producing flora. The composition of the organic matter in the treated water is preferably set to be mainly monomeric organic matter. Since the monomeric organic matter is biodegraded by the methane-producing microbial group, the organic substance in the water to be treated can be biodegraded favorably by the characteristic of the water to be treated, and the organic substance can be prevented from remaining in the treatment liquid and prevented. The separation membrane in the latter stage is contaminated. Further, in the present invention, in particular, a content ratio of a compound having a methyl group (tetramethylammonium, dimethylacetamide, dimethylformamide, dimethylammonium) as a monomeric organic substance is contained. The higher organic matter-containing water is used as a treatment target, and the acid-producing microbial group is prevented from generating a film-contaminated substance, thereby preventing membrane contamination by the polymer organic substance.

Further, in the anaerobic treatment mainly composed of the methane-producing microflora, the nitrification reaction does not substantially occur. Therefore, when the treated water contains a nitrogen compound, the nitrogen component is carried into the reverse osmosis membrane device in the biological treatment step without denitrification. Therefore, if the water to be treated does not contain a nitrogen compound, the load on the reverse osmosis membrane device can be reduced. On the other hand, the present inventors have found that when the nitrogen contained in the water to be treated and the liquid supplied to the reverse osmosis membrane device contain a nitrogen component, the concentrated nitrogen component in the reverse osmosis membrane has a function of suppressing the reverse osmosis membrane. The possibility of microbial proliferation. Therefore, in the reverse osmosis membrane apparatus, when the microorganisms are easily proliferated (for example, when the water to be treated contains 10% to 30% of a polymer organic substance), the water to be treated can be actively contained in the nitrogen compound.

In the anaerobic biological treatment tank, in order to biodegrade the organic matter in the water to be treated to prevent membrane fouling in the latter stage, it is preferred that the proportion of the monomeric organic matter in the organic matter in the water to be treated is high. When the water to be treated contains bacteria or a high molecular organic substance, biodegradation of the acid-producing bacteria group as the matrix is caused, and a soluble high-molecular organic substance which causes membrane foulion is formed. When the temperature of the metabolite of the acid-producing microbe is less than 15 ° C or exceeds 40 ° C, only about 30% is decomposed, but if the temperature is 15 ° C or more and 40 ° C or less, about 90% is decomposed. Therefore, when the temperature of the anaerobic biological treatment tank is set to 15 ° C or more and 40 ° C or less, even if the content of the organic substance other than the monomer organic substance is relatively high, membrane fouling can be prevented.

The temperature condition is particularly preferably 30 ° C or more and 40 ° C or less. As described above, the decomposition efficiency of the metabolite of the acid-producing flora differs depending on the temperature conditions, and therefore the characteristics of the water to be treated can be changed depending on the temperature conditions. Specifically, when the temperature condition is 15 ° C or more and less than 30 ° C, it is preferred that the proportion of the monomer organic matter in the organic matter in the water to be treated is 75% or more. Further, when the temperature condition is less than 15 ° C or more than 40 ° C, it is preferred to set the ratio of the monomer organic matter to 90% or more.

Further, when the pH is 6 or more and 9 or less, the metabolite of the acid-producing flora can be well decomposed, and if the pH exceeds this range, the decomposition rate is lowered to about 30%. Therefore, it is preferred to adjust the pH of the liquid in the tank of the anaerobic biological treatment tank to 6 or more and 9 or less, but there is also a case where the production of metabolites of the acid-producing microflora is small, that is, the monomer organic matter. The case where the ratio is sufficiently high (substantially 100%) or the like may not be adjusted.

The liquid in the tank of the anaerobic biological treatment tank may contain an ammonium salt contained in the water to be treated or an ammonium salt which is formed by decomposition of an organic nitrogen compound contained in the water to be treated. The ammonium salt reacts with carbon dioxide generated by decomposition of organic matter in the anaerobic biological treatment tank to form ammonium hydrogencarbonate. Therefore, when the treated water contains a nitrogen compound, the pH of the liquid in the tank of the anaerobic biological treatment tank can also be maintained in the vicinity of neutral without adding neutralizing chemicals.

Since the treatment liquid flowing out from the anaerobic biological treatment tank contains microorganisms, after the solid-liquid separation is performed, the water (separated water) from which the solid component is removed is desalted by a reverse osmosis membrane device to become a raw material for pure water production. . A membrane separation device equipped with a filtration membrane can be used for solid-liquid separation. As the separation membrane, an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane) may be used, and it is preferred to use a membrane having a smaller pore diameter (for example, 100 nm or less) than the diameter of the usual methane-producing microflora.

Further, the treatment liquid from the anaerobic biological treatment tank contains ammonium hydrogencarbonate or an organic material which has not been biologically treated, which is produced in the anaerobic biological treatment tank. A part of these residual substances were removed in the membrane separation apparatus, but the other parts were not removed in the membrane separation apparatus and brought into the reverse osmosis membrane apparatus to be concentrated. Therefore, the concentrated water (brine) discharged from the reverse osmosis membrane device contains ammonium hydrogencarbonate or the like which is concentrated about 10 times. Therefore, unlike the water to be treated, the brine is treated by biological, chemical or/and physical methods.

The treatment method of the brine can be selected according to its characteristics, for example, biological treatment, and treatment for aerobic or anaerobic biological denitrification can be mentioned. Any one of heterotrophy or autotrophy may be used for biological nitrogen removal.

Examples of the chemical treatment include a method of changing the pH to insolubilize impurities contained in the brine, a method of adding a chemical which forms a compound with impurities in the brine, and the like. Examples of the chemical used in the chemical treatment include an acid or a base which changes a pH value, a coagulant, and a seed crystal which precipitates impurities in the brine. More specifically, sulfuric acid which reacts with an ammonium salt to form ammonium sulfate, various acids which solidify proteins, and the like can be given.

As the physical treatment, distillation may be mentioned; ammonia may be volatilized by aeration. In order to prevent ammonia from volatilizing in the form of a gas, it is preferred to carry out the distillation under acidic conditions or to carry out heating under reduced pressure. On the other hand, when ammonia is volatilized by aeration, it can be set as an alkali condition and a large amount of air is used for aeration.

The brine may also be treated in combination with the above treatment. For example, a method in which an acid is added to a brine to insolubilize ammonia (amine), and then distilled by an evaporator to recover water is mentioned. This method has an advantage that water can be recovered while reducing the amount of waste containing ammonia.

In addition, the present invention is applied not only to semiconductors but also to the manufacturing process drainage of an electronic industrial factory such as a liquid crystal display, thereby being capable of containing a polymer component or various compounds in a manner not as good as that of a food factory drainage or a sewage treatment plant. In this case, the treatment is efficiently performed by anaerobic biological treatment. In addition to this, it is also possible to use organic substances contained in water such as chemical plant drainage and drainage with relatively clear concentration. The composition of these drainages is clear, and therefore has the advantage of being able to use laboratory experiments to know the processing capabilities.

[Effects of the Invention]

In the present invention, the organic matter-containing water mainly composed of a monomeric organic substance is biologically treated under anaerobic conditions to suppress the nitrification reaction, and the salt concentration increase due to the addition of the pH adjusting chemical is suppressed. It can inhibit the formation of metabolites by the acid-producing microflora, thereby preventing the contamination of the separation membrane and decomposing the organic matter by the methane-producing microflora. In the present invention, after the anaerobic biological treatment, the biological treatment liquid in which the organic matter is sufficiently decomposed can be obtained without performing the aerobic biological treatment. Therefore, it is possible to suppress the formation of the polymer organic matter by the acid-producing microbial group and the aerobic microbial group, and to reduce the amount of residual organic matter in the treatment liquid. Therefore, contamination of the separation membrane at the time of membrane separation in the latter stage of the biological treatment step can be prevented. Further, the substance which has not been removed in the anaerobic treatment can be concentrated by a reverse osmosis membrane device and subjected to other treatments, whereby the water recovery rate can be improved.

The above described features and advantages of the present invention will be more apparent from the following description.

Hereinafter, the present invention will be described in detail using the drawings. Hereinafter, the same members are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

(Embodiment 1)

Fig. 1 is a schematic view showing a biological treatment apparatus (hereinafter simply referred to as "processing apparatus") 100 for water containing organic substances used in the present invention. The processing apparatus 100 includes an anaerobic biological treatment tank (hereinafter referred to as "reactor") 110, a membrane separation device 112, and a reverse osmosis membrane device 114. A raw water pipe 130 is connected to the inlet of the reactor 110. The reactor 110 is connected to the membrane separation device 112 via a treatment liquid pipe 132, and the membrane separation device 112 is connected to the reverse osmosis membrane device 114 via a separation water pipe 134. A permeate water pipe 136 is connected to the outlet of the reverse osmosis membrane device 114.

The first heat exchanger 121 is provided in the middle of the raw water pipe 130, and the second heat exchanger 122 is provided in the middle of the permeate pipe 136. The first heat exchanger 121 and the second heat exchanger 122 are connected by the fluid pipe 139, and the fluid used for heat exchange is circulated between the first heat exchanger 121 and the second heat exchanger 122. The first heat exchanger 121, the second heat exchanger 122, and the fluid tube 139 constitute a heat recovery heating device.

A drain pipe 135 and an exhaust pipe 131 are connected to the reactor 110. The excess sludge in the reactor 110 is discharged from the sludge discharge pipe 135, and the gas generated in the reactor 110 is discharged from the exhaust pipe 131. The exhaust pipe 131 is connected to the membrane separation device 112, and is configured to aerobically clean a separation membrane (not shown) provided in the membrane separation device 112, and functions as a cleaning device. Further, a return pipe 133 is also connected to the membrane separation device 112, and an outlet end of the return pipe 133 is connected to the reactor 110. In the reverse osmosis membrane device 114, a brine tube 137 is connected to the concentration side.

In the present invention, the water to be treated is supplied from the raw water pipe 130 to the reactor 110. It is preferable to supply the treated water having 70% or more of the organic matter to the entire reactor 110 to the reactor 110. The suitable operating conditions for the reactor 110 are as described above, with a pH of 6 to 9, and a temperature of 15 to 40 ° C, especially 30 to 40 ° C. Under such a condition, when a polymer organic substance which does not become a matrix of the methane-producing microbial group is contained, it is possible to prevent membrane contamination by the acid-producing microbial metabolite.

The methane-producing microbe in the reactor 110 may be in any form of granules or floating, and the methane-producing microbes are more difficult to form a viscous substance than the acid-producing bacterium, and thus it is difficult to form granulated sludge. Therefore, the sludge in the reactor 110 is easily contained in the treatment liquid discharged from the reactor 110.

In the present invention, since the membrane separation device 112 is provided in the subsequent stage of the reactor 110, the microorganisms contained in the treatment liquid can be satisfactorily subjected to solid-liquid separation. Preferably, as shown in this embodiment, the membrane separation device 112 is provided separately from the reactor 110. As the membrane, an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane) can be used, and it is preferred that the pore diameter is smaller than the diameter of a usual methane-producing bacterium, and specifically, the pore diameter is preferably about 100 nm or less.

The module form of the membrane separation device 112 is not particularly limited. However, it is preferable that the sludge fed from the reactor 110 is not easily clogged or retained inside the membrane separation device 112, and can be suitably used, for example. In the form of a tube or a flat membrane. In addition, as shown in the present embodiment, the separation membrane which separates the liquid component and the solid component in the treatment liquid is a so-called tank type outside the reactor 110, and it is easy to control the membrane surface flow rate, thereby preventing the membrane surface. It is better from the point of view of pollution.

In the present embodiment, the membrane separation device 112 is connected to the exhaust pipe 131, and the treatment liquid is sent from the reactor 110 to the membrane separation device 112 together with the generated gas. The separation membrane is aerated and cleaned while moving along the water path to be treated in the membrane separation device 112. The treatment liquid supplied to the membrane separation device 112 is subjected to solid-liquid separation while passing through the inside of the apparatus, and the separated water from which the solid component is removed is discharged from the permeate side to the outside of the apparatus. On the other hand, the concentrated concentrated sludge liquid in which the solid component is concentrated is moved together with the gas in the liquid to be treated flow path of the membrane separation device 112, and is returned from the return pipe 133 to the reactor 110.

The methane-producing bacteria group has a slower growth rate than the aerobic microorganisms. However, if such a sludge is returned and the sludge concentration in the reactor 110 is maintained at about 4,000 mg/L to 10,000 mg/L, it is obtained. The rate of decomposition is the same as that in the aerobic biological treatment of aerobic activated sludge. Therefore, when the sludge concentration is in the above range, the hydraulic retention time of the reactor 110 can be made 0.5 to 2 days. The excess sludge is appropriately extracted from the reactor 110 via the drain pipe 135, and the sludge concentration in the reactor 110 is adjusted.

The separated water of the solid component is separated from the membrane separation device 112, and is desalted in the reverse osmosis membrane device 114 installed in the subsequent stage of the membrane separation device 112 to be used as raw water for pure water production. In the present embodiment, the reactor 110 is operated at 30 ° C to 40 ° C, and the temperature of the treatment liquid is also 30 ° C to 40 ° C. In the case where the aerobic treatment is not performed and the temperature is not artificially lowered, the treatment liquid discharged from the reactor 110 is sent to the membrane separation device 112 and the reverse osmosis membrane device 114. The liquid at about 30 ° C is easily reversed. Since the permeable membrane is separated, the flux of the reverse osmosis membrane device 114 can be increased by sending the treatment liquid from the reactor 110 to the reverse osmosis membrane device 114 in a warm state.

The liquid withdrawn from the reverse osmosis membrane unit 114 is still warm. Therefore, in the present embodiment, the second heat exchanger 122 provided in the middle of the permeate water pipe 136 that discharges the permeated water exchanges heat with the permeated water to perform heat recovery. The heat exchange medium heated by the heat exchange in the second heat exchanger 122 is sent to the first heat exchanger 121 via the fluid pipe 139. In the first heat exchanger 121, the raw water sent from the raw water pipe 130 is heated by the heated heat exchange medium and sent to the reactor 110.

The permeated water of the salt is removed by treatment in the reverse osmosis membrane device 114, and can be used as raw water for producing pure water. Specifically, in the rear stage of the reverse osmosis membrane device 114, a device constituting a pure water producing device such as a decarbonation device, an ion exchange device, or an ultraviolet ray sterilizing device is disposed, and the osmosis discharged from the reverse osmosis membrane device 114 is performed by using these devices. The water is treated, whereby pure water can be produced. When the concentrated water is treated separately, water can be recovered in the same manner as the permeated water.

[Examples]

[Example 1]

As Example 1, an experiment was conducted using an experimental apparatus that mimics the processing apparatus 100 shown in Fig. 1. The reactor 110 of the experimental apparatus was operated under the conditions of an effective volume of 1 m ³ and a hydraulic retention time of 0.5 days. In the reactor 110, the granular sludge discharged from the anaerobic reactor for treating methanol is cultured in a liquid to be treated described later to maintain the floating sludge. The concentration of the floating sludge in the reactor 110 was 4,000 mg/L, and 40% of the existing amount (wet weight comparison) was a methane-producing flora and 60% was a self-decomposing residue of the methane-producing flora.

As the water to be treated, organic-containing water having a total organic carbon concentration of 750 mg/L, a nitrogen concentration of 218 mg/L, and a phosphorus concentration of 1.0 mg-P/L was used. The composition of the total organic matter was: tetramethylammonium hydroxide concentration of 250 mg/L, monoethanolamine concentration of 250 mg/L, and acetic acid concentration of 250 mg/L, and the content ratio of the monomer organic matter to the total organic carbon was substantially 100%.

The treated water was warmed so that the temperature of the liquid in the tank in the reactor 110 reached 35 ° C, and the pH of the liquid in the tank was adjusted to 7.5. 104 tubular UF membranes (ultrafiltration membranes having a pore diameter of 30 nm) having a diameter of 0.52 cm were disposed in the membrane separation device 112, and the biological treatment liquid discharged from the reactor 110 was flowed into the tube together with the gas, and the concentrated liquid and the gas were returned. To reactor 110. The permeate amount (flux) of the membrane separation device 112 was 1.0 m/day.

The experiment was continued for 30 days under the above conditions, and as a result, the flux of the membrane separation device 112 was maintained at the above value, and the water flow resistance was at most 30 kPa. The TOC concentration of the separated water obtained from the membrane separation device 112 was in the range of 3 mg/L to 4 mg/L during the experiment, and the TOC removal rate was 99.5%. Further, the reverse osmosis membrane device 114 (a spiral reverse osmosis membrane device equipped with a wholly aromatic polyamine-based ultra-low pressure membrane as a reverse osmosis membrane) was desalted at 750 kPa, and the amount of permeated water was maintained after 20 hours. 90% at the beginning of watering.

[Embodiment 2]

In Example 2, an MF film having a pore diameter of 400 nm was used instead of the UF film used in Example 1. The experiment was carried out under the same conditions as in Example 1. As a result, the TOC concentration of the separated water from the membrane separation apparatus equipped with the MF membrane was in the range of 3 mg/L to 4 mg/L in the same manner as in Example 1. Further, the flux of the membrane separation device 112 was maintained at 1.0 m/day, and the flux of the separated water was treated by the reverse osmosis membrane device 114 in the same manner as in Example 1, even after 20 hours from the start of the water passage. Maintained at the original 90%. On the other hand, the water resistance is up to 40 kPa, which is higher than that of the first embodiment. Since the average diameter of the methane-producing bacteria in the sludge in the reactor 110 is 800 nm, it is presumed that when the MF membrane is used, the methane-producing bacteria block the pores of the separation membrane and cause clogging of the membrane.

[Comparative Example 1]

The characteristics of the water to be treated were changed in Comparative Example 1. Specifically, in the treated water used in Example 1, 500 mg-TOC/L of sewage sludge was added, and the ratio of the monomer organic matter to the total organic carbon was adjusted to 58%. Further, since such treated water is used, the sludge composition in the reactor 110 also changes. Specifically, the sludge concentration of the floating sludge in the reactor 110 used in Comparative Example 1 was 8,000 mg/L, and 20% of the existing amount (wet weight comparison) was a methane-producing flora, and the acid-producing flora was 20%. The remaining 60% are bacteria and self-decomposing residues from sewage sludge.

The experiment was carried out under the same conditions as in Example 1 except that the characteristics of the water to be treated were changed and the microorganism phase in the reactor 110 was changed. As a result, the flux of the membrane separation device 112 was slowly lowered, and the water resistance exceeded 20 kPa after 20 days from the start of the experiment. In Comparative Example 1, the TOC concentration of the separated water of the membrane separation device 112 was from 18 mg/L to 43 mg/L.

[Example 3]

In Example 3, the amount of sewage sludge added to the water to be treated was set to 300 mg-TOC/L (the ratio of the monomer organic matter was about 71%). The sludge composition in the reactor 110 also changes as the characteristics of the treated water change. Specifically, the sludge concentration of the floating sludge in the reactor 110 used in Example 3 was 8,000 mg/L, and 30% of the existing amount (wet weight comparison) was a methane-producing flora, and the acid-producing flora was 30%.

The experiment was carried out under the same conditions as in Comparative Example 1, except that the characteristics of the water to be treated and the microorganism phase in the reactor 110 were changed. As a result, the flux of the membrane separation device 112 exhibited the same behavior as in Example 1, the TOC concentration of the separated water was 3 mg/L to 5 mg/L, and the flux of the reverse osmosis membrane device 114 for treating the separated water was maintained at 88%. .

According to the above experiment, when 70% or more of the organic matter in the water to be treated is a monomeric organic substance and anaerobic treatment is carried out using sludge containing a methane-producing microbial flora, clogging of the separation membrane in the latter stage of biological treatment can be prevented.

[Reference Example 1]

The temperature of the liquid in the tank of the reactor 110 in Example 3 was set to 10 °C. As a result, the flux of the membrane separation device 112 decreased, and the water passage resistance exceeded 30 kPa after 7 days. Further, the temperature of the liquid in the tank of the reactor 110 was set to 50 ° C separately from this, and as a result, the flux of the membrane separation device 112 was lowered, and the water-passing resistance exceeded 30 kPa after 3 days.

[Reference Example 2]

The pH of the liquid in the tank of the reactor 110 in Example 3 was set to 5. As a result, the water passing resistance of the membrane separation device 112 increased rapidly, and the water passing resistance exceeded 30 kPa after 10 days. Further, the pH of the liquid in the tank of the reactor 110 was set to 10 separately from this, and as a result, the water flow resistance of the membrane separation device 112 was rapidly increased, and the water-passing resistance exceeded 30 kPa after 8 days.

[Comparative Example 2]

In Comparative Example 2, a diffusing device that blows air was provided inside the reactor, whereby the reactor became an aerobic biological treatment tank. Except that the reactor was changed to aerobicity, the experiment was carried out under the same conditions as in Example 1. As a result, the TOC concentration of the treatment liquid flowing out from the aerobic biological treatment tank was 3 mg/L to 4 mg as in Example 1. /L range. However, the flux of the membrane separation device 112 maintains a predetermined flux for only 20 days. Further, in the liquid in the tank of the aerobic biological treatment tank, the soluble TOC was contained at a concentration of 200 mg/L. On the other hand, the solubility TOC concentration of the liquid in the tank of the anaerobic reactor of Example 1 was about 10 mg/L. As described above, in Comparative Example 2, the solubility TOC concentration in the liquid in the tank was higher than that in Example 1, and the amount of the polymer organic matter constituting the soluble TOC was compared with the water to be treated introduced into the aerobic biological treatment tank. The latter is about 60 times.

The conversion ratio of the sludge (bacteria) to the organic matter in the water to be treated introduced into the biological treatment tank is 0.3 g/g for the aerobic microorganism, and 0.04 g/g for the anaerobic microorganism. . Since the polymer organic matter is generated by the recent self-decomposition, it is estimated that the higher the conversion rate, the more polymer organic matter is produced.

Further, in Comparative Example 2, in the same manner as in Example 1, the separated water subjected to membrane separation in the membrane separation device 112 was treated with a reverse osmosis membrane, and as a result, the amount of permeated water after 20 hours was lowered to start. 60% of water. According to Comparative Example 2 and Example 1, it was shown that anaerobic biological treatment using a methane-producing microbial group was carried out instead of aerobic biological treatment, whereby generation of a polymer organic substance in a contaminated separation membrane was suppressed.

Further, in Comparative Example 2, the microbial flora of the aerobic biological treatment tank contained nitrifying bacteria, and the nitrogen component in the raw water was oxidized to nitric acid. Therefore, the pH of the liquid in the tank of the aerobic biological treatment tank is lowered, and the water quality of the treatment liquid is deteriorated. Therefore, the pH was adjusted to 7 by adding a base at a time when the pH of the liquid in the tank was lower than 5. Further, after maintaining the aerobic condition for a certain period of time, the supply of air to the biological treatment tank is stopped to become an anaerobic condition, thereby performing denitrification. When denitrification was carried out under anaerobic conditions, a mineral acid was added to adjust the pH to 7. As a result of performing such a batch type denitrification treatment and adjusting the pH value, the salt concentration in the treatment liquid is increased. Therefore, the osmotic pressure of the reverse osmosis membrane device in the subsequent stage of the membrane separation device is increased by about 100 kPa to 200 kPa as compared with Example 1, and the desalination efficiency of the reverse osmosis membrane device is lowered. Therefore, it is necessary to increase the reverse osmosis membrane device by about 15% to 20%.

According to the above experiment, according to the present invention, the anaerobic biological treatment of the treated water with the monomeric organic matter and the anaerobic sludge containing the methane-producing microflora can reduce the polymer contained in the treatment liquid. The amount of organic matter or undecomposed organic matter, and prevents contamination of the separation membrane.

(Embodiment 2)

Fig. 2 is a schematic view showing a biological treatment apparatus 200 containing water of an organic substance according to a second embodiment of the present invention. The processing apparatus 200 includes an anaerobic biological treatment tank (hereinafter referred to as "reactor") 210, a membrane separation device 212, a reverse osmosis membrane device 214, and an Anammox tank 241 as a concentrated water treatment device. A raw water pipe 230 is connected to the inlet of the reactor 210. The reactor 210 is connected to the membrane separation device 212 via a treatment liquid pipe 232, and the membrane separation device 212 is connected to the reverse osmosis membrane device 214 via a separation water pipe 234. A permeate pipe 236 is connected to the outlet of the reverse osmosis membrane unit 214.

The first heat exchanger 221 is provided in the middle of the raw water pipe 230, and the second heat exchanger 222 is provided in the middle of the permeate pipe 236. The first heat exchanger 221 and the second heat exchanger 222 are connected by the fluid pipe 239, and the fluid used for heat exchange is circulated between the first heat exchanger 221 and the second heat exchanger 222. The first heat exchanger 221, the second heat exchanger 222, and the fluid tube 239 constitute a heat recovery heating device.

A drain pipe 235 and an exhaust pipe 231 are connected to the reactor 210. The excess sludge in the reactor 210 is discharged from the sludge discharge pipe 235, and the gas generated in the reactor 210 is discharged from the exhaust pipe 231. The exhaust pipe 231 is connected to the membrane separation device 212, and the exhaust pipe 231 is configured to be capable of adiabatically cleaning a separation membrane (not shown) provided in the membrane separation device 212, and functions as a cleaning device. Further, a return pipe 233 is connected to the membrane separation device 212, and an outlet end of the return pipe 233 is connected to the reactor 210. In the reverse osmosis membrane device 214, a brine tube 237 is connected to the concentration side. The brine tube 237 is connected to the Anammox tank 241.

In the present invention, the organic-containing water containing the nitrogen compound as the water to be treated is supplied to the reactor 210 via the raw water pipe 230. As described above, the preferred operating conditions of the reactor 210 are a pH of 6 to 9, a temperature of 15 to 40 ° C, especially 30 to 40 ° C. Under such a condition, when the organic substance-containing water containing the polymer organic substance which is not a matrix of the methane-producing microbial group is treated, it is possible to prevent membrane contamination by the acid-producing microbial metabolite.

The methane-producing microbe in the reactor 210 may be in any form of granules or floating, and the methane-producing microbes are less likely to form a viscous substance than the acid-producing bacterium, and thus it is difficult to form granulated sludge. Therefore, the sludge in the reactor 210 is easily contained in the treatment liquid discharged from the reactor 210.

In the present invention, since the membrane separation device 212 is provided in the subsequent stage of the reactor 210, the microorganisms contained in the treatment liquid can be satisfactorily separated into solid-liquid. Preferably, the membrane separation device 212 is provided separately from the reactor 210 as in the present embodiment. As the membrane, an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane) can be used, and it is preferred that the pore diameter is smaller than the diameter of a usual methane-producing bacterium, and specifically, the pore diameter is preferably about 100 nm or less.

The module form of the membrane separation device 212 is not particularly limited. However, it is preferred that the sludge fed from the reactor 210 is not easily clogged or retained inside the membrane separation device 212, and for example, a tubular form or In the form of a flat membrane. In addition, as shown in the present embodiment, the separation membrane which separates the liquid component and the solid component in the treatment liquid is a so-called tank type outside the reactor 110, and it is easy to control the membrane surface flow rate, thereby preventing the membrane surface. The point of view of pollution is better.

In the present embodiment, the membrane separation device 212 is connected to the exhaust pipe 231, and the treatment liquid is sent from the reactor 210 to the membrane separation device 212 together with the generated gas. The separation membrane is aerated and cleaned while moving along the water path to be treated in the membrane separation device 212. The treatment liquid supplied to the membrane separation device 212 is solid-liquid separated while passing through the inside of the apparatus, and the separated water from which the solid component is removed is discharged from the permeate side to the outside of the apparatus. On the other hand, the concentrated sludge liquid in which the solid component is concentrated is moved together with the gas in the liquid to be treated flow path of the membrane separation device 212, and is returned from the return pipe 233 to the reactor 210.

The methane-producing microbial group has a slower growth rate than the aerobic microorganism, but if such sludge is returned and the sludge concentration in the reactor 210 is maintained at about 4,000 mg/L to 10,000 mg/L, The rate of decomposition is the same as in the case of aerobic biological treatment using aerobic activated sludge. Therefore, when the sludge concentration is in the above range, the hydraulic retention time of the reactor 210 can be made 0.5 to 2 days. The excess sludge is appropriately withdrawn from the reactor 210 via the sludge discharge pipe 235 to adjust the sludge concentration in the reactor 210.

The separated water of the solid component is separated in the membrane separation device 212, and is desalted in the reverse osmosis membrane device 214 provided in the subsequent stage of the membrane separation device 212 to be used as raw water for pure water production. In the present embodiment, the reactor 210 is operated at 30 ° C to 40 ° C, and the temperature of the treatment liquid is also 30 ° C to 40 ° C. When the aerobic treatment is not performed and the temperature is not artificially lowered, the treatment liquid discharged from the reactor 210 is sent to the membrane separation device 212 and the reverse osmosis membrane device 214. The liquid at about 30 ° C is easily subjected to reverse osmosis membrane. Since it is separated, the flux of the reverse osmosis membrane device 214 can be increased by feeding the treatment liquid from the reactor 210 to the reverse osmosis membrane device 214 in a warm state.

The liquid discharged from the reverse osmosis membrane device 214 is still warm. Therefore, in the present embodiment, the second heat exchanger 222 provided in the middle of the permeate water pipe 236 that discharges the permeated water exchanges heat with the permeated water to perform heat recovery. The heat exchange medium heated by the heat exchange in the second heat exchanger 222 is sent to the first heat exchanger 221 via the fluid pipe 239. In the first heat exchanger 221, the raw water sent from the raw water pipe 230 is heated by the heated heat exchange medium, and then sent to the reactor 210.

The permeated water of the salt is removed by treatment in the reverse osmosis membrane device 214, and can be used as raw water for producing pure water. Specifically, in the latter stage of the reverse osmosis membrane device 214, a device constituting a pure water producing device such as a decarbonation device, an ion exchange device, or an ultraviolet ray sterilizing device is disposed, and the permeated water discharged from the reverse osmosis membrane device 214 is used using these devices. The treatment is carried out, whereby pure water can be produced. The concentrated concentrated water from which the salt discharged from the reverse osmosis membrane device 214 is concentrated is discharged from the brine tube 237.

The treatment apparatus 200 of the second embodiment has a biological treatment tank that holds a self-supporting nitrogen-removing microorganism (Anammox microorganism) as a concentrated water treatment device. In the Anammox tank 241, a portion of the ammonia in the concentrated water supplied from the brine tube 237 is oxidized to nitrous acid under microaerobic conditions, and nitrogen is generated from ammonia and nitrous acid by the biological reaction of the Anammox microorganism under anaerobic conditions. And remove nitrogen.

The effluent from the Anammox tank 241 is discharged from the pipe 242, and may be further processed as needed to be used as raw water for pure water production. Alternatively, the effluent may be subjected to solid-liquid separation in a solid-liquid separation device (not shown) as needed, and the solid component may be returned as a return sludge, and the liquid component may be discharged or recovered.

(Embodiment 3)

The concentrated water discharged from the reverse osmosis membrane device 214 can also be treated by a method other than biological treatment. Fig. 3 is a schematic view showing a processing apparatus 300 according to a third embodiment of the present invention. The processing apparatus 300 is different from the processing apparatus 200 in that it has a reaction column 343 instead of the Anammox tank 241 as a concentrated water treatment apparatus. A chemical injection device (not shown) is connected to the middle of the brine pipe 237 in which the concentrated water is supplied to the reaction column 343, and a chemical which reacts with ammonia in the concentrated water to form a solid matter is added. To the concentrated water, for example, phosphoric acid and a magnesium salt are added as a chemical, and magnesium ammonium phosphate is formed in the reaction column 343 to produce struvite crystals. The struvite crystals can be discharged from the reaction column 343 to be used as a fertilizer or the like, and the deaminated water of ammonia can be removed after separation from the crystals, and can be recovered as raw water produced by pure water.

(Embodiment 4)

Fig. 4 is a schematic view showing a processing apparatus 400 according to a fourth embodiment of the present invention. The processing device 400 includes an evaporator 445 as a concentrated water treatment device. In the treatment apparatus 400, concentrated water is introduced into the evaporator 445 to perform vacuum distillation, and distilled water is taken out from the distillation water pipe 446 to be used as raw water for pure water production. Although not shown in the drawing, sulfuric acid may be added to the concentrated water before the distillation treatment, so that the pH of the concentrated water becomes about 4 to 6, and ammonia is made into ammonium sulfate, thereby recovering ammonia.

FIG. 5 shows another method of treating concentrated water by a method in which two or more of biological treatment, chemical treatment, and physical treatment are combined. In the processing apparatus 500 of FIG. 5, the biological treatment tank (Anammox tank 241) and the evaporator 445 are combined to form a concentrated water treatment apparatus. In the treatment apparatus 500, by first biologically treating the concentrated water, the amount of acid required for adjusting the pH of the water to be treated supplied to the evaporator 445 can be reduced.

[Examples]

[Example 4]

In the fourth embodiment, the experiment was carried out using the experimental apparatus which imitated the processing apparatus 200 shown in FIG. The reactor 210 of the experimental apparatus was operated under the conditions of an effective volume of 1 m ³ and a hydraulic retention time of 0.5 day. In the reactor 210, the granular sludge discharged from the anaerobic reactor for treating methanol is cultured in a treatment liquid to be described later to maintain the floating sludge. The concentration of the floating sludge in the reactor 210 is 4,000 mg/L, and 40% of the existing amount (wet weight comparison) is a methane-producing flora, and 60% is a self-decomposing residue of the methane-producing flora.

The water to be treated was an organic-containing water having a total organic carbon (TOC) concentration of 500 mg/L, a nitrogen concentration of 152 mg/L, and an inorganic salt concentration of 1,180 mg/L. Carbon and nitrogen are essentially derived from tetramethylammonium hydroxide at a concentration of 480 mg/L for TOC and 140 mg/L for N.

The treated water was warmed so that the temperature of the liquid in the tank in the reactor 210 reached 35 °C. 104 tubular UF membranes (pore diameter: 30 nm) having a diameter of 0.52 cm were disposed in the membrane separation device 212, and the biological treatment liquid discharged from the reactor 210 was flowed into the tube together with the gas, and the concentrated liquid and the gas were returned to the reactor 210. . The permeate amount (flux) of the membrane separation device 212 was set to 1.0 m/day. The separated water obtained from the membrane separation device 212 was concentrated 10 times at 0.75 MPa by a reverse osmosis membrane device 214 (a spiral reverse osmosis membrane device having a wholly aromatic polyamine-based ultra-low pressure membrane as a reverse osmosis membrane).

After the experiment was started under the above conditions for 30 days, tetramethylammonium hydroxide was decomposed, and the TOC concentration of the separated water from the membrane separation device 212 was 5 mg/L to produce trimethylamine and ammonia. The TOC for separating water is basically trimethylamine at a concentration of 4 mg/L, and the remaining 1 mg/L is a high molecular organic substance produced by microorganisms. Further, the ammonia concentration of the separated water is in the range of 135 mg-N/L to 140 mg-N/L. The ammonia reacts with carbon dioxide (concentration of about 120 mg-C/L) produced by methane fermentation in the reactor 210 to form ammonium hydrogencarbonate. Therefore, the pH of the liquid in the tank of the reactor 210 can be maintained at pH 7.0 to pH 7.5 without adding a neutralizing reagent.

The reverse osmosis membrane device 214 for desalting the separated water was operated at a flux of 0.95 m/day at 0.75 MPa for 60 days from the start of the experiment. The concentrated water obtained from the reverse osmosis membrane device 214 has a pH of about 8.5, a trimethylamine concentration of 40 mg-C/L, an ammonium hydrogencarbonate concentration of 1,400 mg-N/L, and a high molecular organic concentration of 10 mg-C/. The recovery of L, salts (ammonium salts) and organics is approximately 100%.

The concentrated water was biologically treated in the Anammox tank 241 under micro-aerobic/anaerobic conditions. The load on the Anammox tank 241 was 3 kg-N/m ³ /day. By the treatment in the Anammox tank 241, 99% of trimethylamine and ammonia in the concentrated water are biodegraded, and the BOD concentration of the treatment liquid flowing out from the Anammox tank 241 is 10 mg/L or less, and the SS concentration is also 10 mg/L or less. The nitrogen concentration is 10 mg-N/L.

[Example 5]

The experiment was carried out under the same conditions as in Example 4 except that the experimental apparatus simulating the processing apparatus 300 of Fig. 3 was used in the fifth embodiment. In Example 5, a 2% magnesium chloride aqueous solution as a magnesium salt was added in an amount of 800 mg/L in the middle of the brine tube 237, and a potassium phosphate solution was added. Further, sodium hydroxide was added to bring the pH to 11, and the ammonium hydrogencarbonate was dissociated to release the ammonium ions. The capacity of the reaction column 343 was 20 L, and concentrated water to which the above chemical was added was passed under conditions of 200 L/day. As a result, ammonium ions reacted with phosphorus and magnesium to form struvite crystals having a diameter of about 2 mm to 3 mm. The treated water taken out from the reaction column 343 via the pipe 344 has a TOC concentration of 50 mg/L and a nitrogen concentration of 140 mg/L, and 90% of the ammonia contained in the concentrated water can be removed. Further, the struvite crystals were taken out from the reaction column 343 and analyzed, and as a result, the main components were ammonia, phosphorus, and magnesium, and almost no heavy metals were used, and they were used as fertilizers.

[Embodiment 6]

The experiment was carried out under the same conditions as in Example 4 except that the experimental apparatus simulating the processing apparatus 400 of Fig. 4 was used in the sixth embodiment. In Example 6, sulfuric acid was added to the middle of the brine tube 337 from a chemical addition device (not shown), and the alkalinity of the concentrated water supplied to the evaporator 445 was 0 (pH 4.8). The evaporator 445 is distilled by performing a reduced pressure and heating the concentrated water to 40 ° C, and distilled water is taken out from the distillation water pipe 446. The distilled water had a TOC concentration of 0.01 mg-C/L and a nitrogen concentration of 0.2 mg-N/L. Further, the ammonium sulfate slurry remaining in the evaporator 445 is recovered, and as a result, 98% of the ammonium in the concentrated water can be recovered as an ammonium sulfate slurry.

[Embodiment 7]

In the seventh embodiment, the experimental apparatus which imitated the processing apparatus 500 of FIG. 5 was used, and the treatment liquid obtained by the biological treatment in the Anammox tank 241 of Example 4 was further distilled by the evaporator 445. In Example 7, the ammonia concentration of the liquid supplied to the evaporator 445 was 70 mg-N/L, which was lower than that of Example 6. Therefore, the amount of acid necessary for lowering the pH was 1/20 of that of Example 6. . Further, the water quality of the distilled water discharged from the evaporator 445 is a TOC concentration of 0 mg-C/L and a nitrogen concentration of 0 mg-N/L.

[Comparative Example 3]

In Comparative Example 3, a diffusing device that blows air was provided inside the reactor, whereby the reactor became an aerobic biological treatment tank. Except that the reactor was changed to aerobicity, the pH adjustment of the aerobic biological treatment tank was not carried out under the same conditions as in Example 4, so that the nitrification reaction was found one week after the start of the experiment. The pH of the liquid in the tank is reduced to about 5.0 to 5.5. As a result, the TOC concentration of the treatment liquid flowing out from the aerobic biological treatment tank is about 100 mg/L to 120 mg/L, and the flux of the reverse osmosis membrane device for desalting the separated water obtained from the membrane separation device is implemented. Half of the example 4.

[Comparative Example 4]

In Comparative Example 3, sodium hydroxide was added to the aerobic biological treatment tank to adjust the pH of the liquid in the tank to a range of 6.5 to 7.5. As a result, the TOC concentration of the treatment liquid flowing out of the aerobic biological treatment tank can be lowered to 10 mg/L. However, the treatment liquid contains nitric acid at a concentration of about 130 mg/L to 140 mg/L, and the sodium hydroxide added to adjust the pH value causes the salt concentration to increase. Therefore, the flux of the reverse osmosis membrane device for desalting the separated water obtained from the membrane separation device is limited to 60% of that of Example 4.

[Comparative Example 5]

In Comparative Example 4, a denitrification tank was provided in the subsequent stage of the aerobic biological treatment tank to form a treatment apparatus 600 having the configuration shown in Fig. 6. The treatment device 600 has an aerobic biological treatment tank (aerobic reactor 610) instead of the anaerobic biological treatment unit (reactor 210) used in the embodiment, and has a denitrification in the latter stage of the aerobic reactor 610. The denitrification tank 613 and the re-aeration tank 611 of the bacteria. Methanol was added to the treatment liquid flowing out of the aerobic reactor 610, and sulfuric acid was added to the denitrification tank 613 to maintain the pH at 6.5 to 7.5, and the denitrification treatment was performed. The effluent from the denitrification tank 613 is sent to the re-aeration tank 611 via the pipe 632B, re-aerated in the re-aeration tank 611, and sent to the membrane separation device 612 via the pipe 632C. As a result, the flux of the reverse osmosis membrane device 614 for desalting the separated water obtained from the membrane separation device 612 was 80% of that of Example 4 two weeks after the start of the experiment. However, the flux of the reverse osmosis membrane device 614 was reduced to 50% of Example 4 one month after the start of the experiment.

Therefore, the reverse osmosis membrane was taken out and observed under a microscope, and as a result, a large amount of biofilm adhered to the surface. Since the biofilm was hardly adhered to the reverse osmosis membrane of the reverse osmosis membrane device used in Example 4, it was estimated that the flux was lowered due to the adhesion of the biofilm in Comparative Example 5. In the examples, the reason why the biofilm was not attached to the reverse osmosis membrane was considered to be the following two points. In the reverse osmosis membrane device, the concentration of the salt increases the pH of the brine to 8.5, so that ammonia is removed from the ammonium hydrogencarbonate, and the proliferation of the microorganism is inhibited by the toxicity of ammonia. Further, for other reasons, the methane-producing microbial group has a slower proliferation rate than the aerobic microorganism, and it is difficult to form a biofilm.

As described above, the methane-producing microbial group is subjected to anaerobic treatment of the organic-containing water, whereby the organic substance can be biodegraded without adding a pH adjusting agent, and the polymer organic substance contaminating the separation membrane can be suppressed. The amount of production.

Further, in the anaerobic treatment step using the methane-producing microflora, ammonium bicarbonate is formed from ammonia and carbon dioxide, and is concentrated in the reverse osmosis membrane device without aerobic treatment, thereby suppressing A biofilm is formed in the reverse osmosis membrane device. That is, it is possible to prevent contamination of the reverse osmosis membrane when the substance which cannot be removed by the anaerobic treatment step is concentrated in the reverse osmosis membrane apparatus.

[Industrial availability]

The present invention can be used for biological treatment of water containing organic matter and reuse in pure water production.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 200, 300, 400, 500. . . Biological treatment device

110. . . Anaerobic biological treatment tank

112, 212. . . Membrane separation device

114, 214, 614. . . Reverse osmosis membrane device

121, 221, 621. . . First heat exchanger (heat recovery heating device)

122, 222, 622. . . Second heat exchanger (heat recovery heating device)

130, 230. . . Raw water pipe

131, 231. . . exhaust pipe

132, 232. . . Treatment liquid tube

133, 233. . . Return tube

134, 234. . . Separation water pipe

135, 235. . . Drain pipe

136, 236. . . Permeate pipe

137, 237. . . Brine tube

138, 238, 242, 344, 446, 630, 631, 632, 632B, 632C, 633, 634, 635, 636, 637, 638, 639, 642. . . Piping

139, 239. . . Fluid tube

210. . . Anaerobic biological treatment tank (reactor)

241, 641. . . Anammox tank (concentrated water treatment unit)

343. . . Reaction column

445. . . Evaporator

600. . . Comparative biological treatment device

610. . . Aerobic biological treatment tank (aerobic reactor)

611. . . Re-aeration layer

612. . . Membrane separation device

613. . . Nitrogen removal tank

Fig. 1 is a schematic view showing a biological treatment apparatus according to a first embodiment of the present invention.

Fig. 2 is a schematic view showing a biological treatment apparatus according to a second embodiment of the present invention.

Fig. 3 is a schematic view showing a biological treatment apparatus according to a third embodiment of the present invention.

Fig. 4 is a schematic view showing a biological treatment apparatus according to a fourth embodiment of the present invention.

Fig. 5 is a schematic view showing a biological treatment apparatus according to a fifth embodiment of the present invention.

Fig. 6 is a schematic view showing an experimental apparatus used in Comparative Example 5.

100. . . Biological treatment device

110. . . Anaerobic biological treatment tank (reactor)

112. . . Membrane separation device

114. . . Reverse osmosis membrane device

121. . . First heat exchanger (heat recovery heating device)

122. . . Second heat exchanger (heat recovery heating device)

130. . . Raw water pipe

131. . . exhaust pipe

132. . . Treatment liquid tube

133. . . Return pipe

134. . . Separation water pipe

135. . . Drain pipe

136. . . Permeate pipe

137. . . Brine tube

138. . . Piping

139. . . Fluid tube

Claims (18)

A biological treatment method for water containing organic matter, comprising: introducing water containing organic matter into an anaerobic biological treatment tank; performing anaerobic biological treatment using the methane-producing microflora in the anaerobic biological treatment tank; The treatment liquid obtained by the anaerobic biological treatment is subjected to membrane separation without aerobic biological treatment, and the separated water obtained by the membrane separation is treated with a reverse osmosis membrane. The biological treatment method of the organic-containing water according to claim 1, wherein the ratio of the monomer organic matter to the total organic carbon in the organic-containing water is 70% or more. The biological treatment method of the organic-containing water according to the first or second aspect of the invention, wherein the temperature of the liquid in the anaerobic biological treatment tank is 15 ° C or more and 40 ° C or less Anaerobic treatment. The biological treatment method of the organic-containing water according to claim 3, wherein the treatment liquid is heated in the anaerobic treatment process, and the membrane separation and the reverse osmosis membrane treatment are performed. The biological treatment method of the organic substance-containing water according to claim 2, wherein the monomer organic substance is selected from the group consisting of tetramethylammonium hydroxide, monoethanolamine, diethylene glycol monobutyl ether, isopropanol, and Any one or more of the group consisting of methyl acetamide, dimethylformamide, dimethyl hydrazine, and acetic acid. A biological treatment device for water containing organic matter, comprising: an anaerobic biological treatment tank for introducing water containing organic matter and generating methane by using a methane-producing flora; and a membrane separation device connected to the anaerobic biological treatment tank, It is used for membrane separation of the treatment liquid discharged from the anaerobic biological treatment tank; and a reverse osmosis membrane device for treating the separated water of the membrane separation device. The biological treatment apparatus of the organic substance-containing water according to claim 6, wherein the content of the monomeric organic matter to the total organic carbon in the organic-containing water is 70% or more. The biological treatment device for water containing organic matter according to claim 6 or 7, wherein the anaerobic treatment tank has a temperature of the liquid in the tank of 15 ° C or more and 40 or less. The operation is carried out at ° C, and the treatment liquid is supplied to the membrane separation device and the reverse osmosis membrane device in a heated state in the anaerobic treatment tank. The biological treatment device for the organic substance-containing water according to claim 8 further includes a heat recovery heating device for heat recovery of the permeated water of the reverse osmosis membrane device, and using the recovered heat to warm the anaerobic Oxygen treatment tank. The biological treatment device for organic-containing water according to claim 6, wherein the membrane separation device comprises a microfiltration membrane or an ultrafiltration membrane. The biological treatment device for the organic substance-containing water according to claim 6, further comprising a cleaning device for supplying the bio-generated gas generated in the anaerobic biological treatment tank to the membrane separation device, The membrane separation device performs aeration cleaning. A biological treatment device for water containing organic matter, comprising: an anaerobic biological treatment tank for introducing water containing organic matter and generating methane by using a methane-producing flora; and a membrane separation device connected to the anaerobic biological treatment tank, a membrane separation for treating the treatment liquid discharged from the anaerobic biological treatment tank; a reverse osmosis membrane device for treating the separation water treatment of the membrane separation device; and a concentrated water treatment device for treating the reverse osmosis membrane device Concentrated water. The biological treatment apparatus of the organic-containing water according to claim 12, wherein the concentrated water treatment apparatus comprises a biological treatment tank different from the anaerobic biological treatment tank. The biological treatment apparatus of the organic substance-containing water according to claim 12 or 13, wherein the concentrated water treatment apparatus includes an evaporator, and the concentrated water is introduced to evaporate to take out distilled water. The biological treatment apparatus of the organic substance-containing water according to claim 12, wherein the concentrated water treatment apparatus includes a reaction column, and a chemical that insoluates impurities in the concentrated water is added to the concentrated water, and the solid is separated. Things. A biological treatment method for water containing organic matter, comprising: introducing water containing organic matter into an anaerobic biological treatment tank containing a group of methane-producing bacteria for anaerobic biological treatment; and treating by using the anaerobic biological treatment The liquid is subjected to membrane separation without aerobic biological treatment; the separated water obtained by the membrane separation is treated with a reverse osmosis membrane; and the concentrated water obtained by the reverse osmosis membrane treatment is treated. The biological treatment method of the organic-containing water according to claim 16, wherein the organic-containing water contains a nitrogen compound. The biological treatment method of the organic substance-containing water according to claim 16 or 17, wherein the concentrated water is subjected to biological treatment different from the anaerobic biological treatment; and the concentrated water is distilled by an evaporator. Processing; and/or treating the concentrated water with chemicals to render the impurities insoluble.