JP4590756B2 - Organic drainage treatment method and organic drainage treatment apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic wastewater treatment method for treating organic wastewater by methane fermentation in the presence of sludge containing anaerobic microorganisms, and an organic wastewater treatment apparatus suitable for carrying out this treatment method. About.
[0002]
[Prior art]
Slurry high-concentration organic effluents such as organic sludge, human waste, and food wastewater are treated by methane fermentation in the presence of anaerobic microorganisms. Such anaerobic treatment is also called anaerobic digestion and has been performed for a long time.
[0003]
Such anaerobic treatment is a technique with many advantages, such as the UASB method, which saves energy and produces a small amount of sludge when the concentration of suspended matter in the introduced organic waste liquid is low. However, when the concentration of the suspended matter is high, sludge composed of undegraded suspended matter and living cells is generated. This sludge is biologically stable and is therefore difficult to reduce significantly even if it is further biologically treated. Therefore, in order to reduce the volume, the following methods are conventionally provided.
[0004]
In the method shown in FIG. 14, after the anaerobic treatment step 1, a reforming step 2 for performing a reforming treatment with ozone is provided, and after this reforming step 2, a solid-liquid separation step 3 for performing solid-liquid separation is provided. It has been. Under such a structure, the dewatering property of sludge is improved by the reforming treatment, and the volume is reduced (Japanese Patent Laid-Open No. 59-96000).
[0005]
In the method shown in FIG. 15, a reforming step 2 for performing a reforming treatment with ozone is provided before the anaerobic treatment step 1, thereby promoting methane fermentation (Japanese Patent Laid-Open No. Sho). 57-22692). In addition, it is thought that produced | generated sludge reduces as a result by promotion of such methane fermentation.
[0006]
In the method shown in FIG. 16, the derived product from the anaerobic treatment step 1 is subjected to solid-liquid separation in the solid-liquid separation step 3, and the separated concentrated sludge is treated in the reforming step 4 in which heat treatment is performed at 100 to 180 ° C. It returns to the anaerobic nitrification tank 1 (Unexamined-Japanese-Patent No. 1-224100).
[0007]
In the method shown in FIG. 17, the derived product from the anaerobic treatment step 1 is subjected to solid-liquid separation in the solid-liquid separation step 3, and the separated concentrated sludge is subjected to reforming treatment by ozone treatment or high-pressure pulse discharge treatment. It processes at the process step 5, and returns to an anaerobic digester (Japanese Patent Laid-Open No. 8-19127).
[0008]
[Problems to be solved by the invention]
However, the above-described method for volume reduction has the following disadvantages.
Since the sludge is sterilized or solubilized in the reforming steps 2, 4, and 5, the nitrogen compound contained in the sludge is dissolved, and thus, in the method shown in FIGS. By sending the sludge derived from the reforming step to the anaerobic treatment step 1, the ammonium ion concentration in the anaerobic treatment tank in which the anaerobic treatment step 1 is performed increases.
[0009]
Then, since ammonium ions are in equilibrium with ammonia, the ammonia concentration increases as the ammonium ion concentration increases. As ammonia is well known to inhibit methanogens, when treating organic wastewater with a high concentration of nitrogen compounds, the above technique may possibly inhibit methane fermentation by anaerobic treatment. There is.
[0010]
Furthermore, an increase in ammonium ions also increases the burden on the subsequent process. In other words, only the anaerobic treatment does not purify the obtained treated water to the quality of water that can be discharged into public water areas. In this case, when there is a nitrogen drainage standard at the discharge destination, a nitrogen removal technique by nitrification denitrification is often used as a post-treatment.
[0011]
In the nitrification denitrification method, the flow is usually in the order of a denitrification step → a nitrification step. Therefore, according to this nitrification denitrification method, the organic nitrogen compound in the treated water introduced in the denitrification process is converted to ammonium ions (ammonium ions remain as they are), and these ammonium ions become nitrite or nitrate ions in the nitrification process, This is returned to the denitrification process and released as nitrogen gas or nitrous oxide by reaction with organic substances introduced into the denitrification process.
[0012]
This denitrification reaction does not proceed completely when the ratio of organic matter to nitrogen compound is low (normally [BOD / N] ratio is 3 or less). In the post-treatment of the anaerobic process, the organic matter is removed even in the anaerobic process, and the [BOD / N] ratio is lowered. Therefore, after the reforming process as in the method for volume reduction described above. As the amount of nitrogen compounds increases, this [BOD / N] ratio becomes lower and further disadvantageous in promoting the denitrification reaction.
[0013]
The present invention has been made in view of the above circumstances, and the object of the present invention is to reduce the volume and at the same time prevent the inhibition of methane fermentation in the anaerobic treatment with ammonia. Another object of the present invention is to provide an organic drainage treatment apparatus suitable for carrying out this method.
[0014]
[Means for Solving the Problems]
In the organic wastewater treatment method of the present invention, anaerobic treatment step of methane fermentation of organic wastewater in the presence of sludge containing anaerobic microorganisms, and nitrification and denitrification of the effluent from the anaerobic treatment step A treatment cycle comprising a nitrification / denitrification step for removing nitrogen compounds by reaction and a return step for returning sludge produced in the nitrification / denitrification step to the anaerobic treatment step is introduced into the treatment cycle. It has been a means for solving the above-mentioned problems to have a reforming step of modifying the sludge thus produced to be easily biodegradable and deriving it.
[0015]
According to this processing method, since a treatment cycle comprising an anaerobic treatment step, a nitrification denitrification step, and a return step is provided, a nitrogen compound is obtained by treating a derivative from the anaerobic treatment step in the nitrification denitrification step. Can be removed and returned to the anaerobic treatment step, thus preventing methane fermentation from being inhibited by ammonia in the anaerobic treatment step.
In addition, since the amount of nitrogen in the treated water finally derived from the treatment system is sufficiently reduced through the nitrification and denitrification step, the [organic matter / N] ratio in the treated water is also increased. The burden on the process can be significantly reduced.
Furthermore, since it has a reforming step in the treatment cycle, the introduced sludge is easily biodegradable and derived, thereby reducing the volume of sludge produced in the entire treatment system. It becomes possible.
[0016]
In the organic wastewater treatment apparatus of the present invention, anaerobic treatment tank for methane fermentation of organic wastewater in the presence of sludge containing anaerobic microorganisms, and nitrification and denitrification of the effluent from the anaerobic treatment tank A treatment cycle comprising a nitrification denitrification tank for reacting to remove nitrogen compounds and a return path for returning sludge generated in the nitrification denitrification tank to the anaerobic treatment tank was introduced into this treatment cycle. It has been a means for solving the above-mentioned problems to have a reforming device for modifying sludge to be readily biodegradable and deriving it.
[0017]
According to this processing apparatus, since the above-described processing method can be performed, it is possible to prevent methane fermentation from being inhibited by ammonia in an anaerobic processing tank, and greatly reduce the burden on the subsequent process. Furthermore, it becomes possible to reduce the volume of sludge generated in the entire treatment system.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
Figure 1 Organic drainage in the present invention FIG. 1 is a schematic configuration diagram for explaining an example of an embodiment of the processing apparatus, and reference numeral 10 in FIG. 1 is an organic drainage processing apparatus. This organic drainage treatment apparatus 10 treats both organic sludge, human waste, slurry-like organic drainage containing high-concentration solids such as food wastewater, and liquid organic drainage. Therefore, it is configured to include a processing cycle 15 including an anaerobic processing tank 11, a nitrification / denitrification tank 12, a solid-liquid separation device 13, and a return path 14.
[0019]
The anaerobic treatment tank 11 has sludge containing anaerobic microorganisms, and specifically, acid-producing bacteria and methane-producing bacteria are present as anaerobic microorganisms. Under such a configuration, in the anaerobic treatment tank 11, the organic matter in the introduced organic drainage is liquefied → low molecular weight → organic acid generated → methane generated in the step of liquefaction by the sludge. To methane fermentation.
[0020]
The nitrification denitrification tank 12 is for removing the nitrogen compound from the derivatized product by causing the derivatized product from the anaerobic treatment tank 11 to react with nitrification and denitrification. In this example, FIG. ) And (c), the tank is appropriately selected from three types of tank configurations and used.
[0021]
The nitrification denitrification tank 12 shown in FIG. 2 (a) is a circulation type constituted by including a denitrification tank 12a having sludge containing denitrifying bacteria and a nitrification tank 12b having sludge containing nitrifying bacteria. The derived matter from the anaerobic treatment tank 11 is treated in the denitrification tank 12a, then treated in the nitrification tank 12b, and then treated again in the denitrification tank 12a, thereby removing nitrogen compounds from the derived substance. It is supposed to be. That is, in this nitrification denitrification tank 12, organic nitrogen is converted to ammonium ions by the action of denitrifying bacteria in the denitrification tank 12a, and subsequently, ammonia ions are oxidized to nitrite ions or nitrate ions by the action of nitrifying bacteria in the nitrification tank 12b (nitrification). Then, again, in the denitrification tank 12a, nitrite ions or nitrate ions are reduced to nitrous oxide or nitrogen gas by the action of denitrifying bacteria, and then released out of the system as they are to remove nitrogen compounds from the derived product. It has become. In addition, oxygen or air is continuously supplied to the nitrification tank 12b by a blower or the like (not shown) so that the nitrification reaction by nitrifying bacteria is continuously performed. Nitrogen is a product of the denitrification reaction, but does not affect the denitrification reaction. Therefore, the use of air is advantageous in terms of cost and handling properties and facility simplicity.
[0022]
Moreover, the nitrification denitrification tank 12 shown in FIG. 2 (b) is an alternating type containing both denitrification bacteria and nitrification bacteria in the sludge therein, and oxygen is intermittently supplied into the sludge. The denitrification reaction by the action of denitrifying bacteria and the nitrification reaction by the action of nitrifying bacteria occur alternately in time. That is, while oxygen or air is supplied by an oxygen or air supply device (not shown) such as a blower or timer, oxidation (nitrification) occurs due to the action of nitrifying bacteria described above, and supply of oxygen or air is stopped. In the meantime, ammonium ionization by the above-mentioned denitrifying bacteria and further reduction to nitrous oxide or nitrogen gas occur.
[0023]
Further, the nitrification denitrification tank 12 shown in FIG. 2 (c) is a coexisting type containing both denitrification bacteria and nitrification bacteria in the sludge in the same manner as in FIG. By controlling the speed and concentration, the denitrification reaction by the action of the denitrifying bacteria and the nitrification reaction by the action of the nitrifying bacteria coexist. That is, for example, if a small amount of oxygen or air is supplied to the bottom of the nitrification denitrification tank 12 while controlling the flow rate, a nitrification reaction occurs due to the action of nitrifying bacteria at the bottom, and oxygen is already consumed and not supplied at the top. Thus, a denitrification reaction due to the action of denitrifying bacteria occurs. Alternatively, when microorganisms form flocs, the floc surface becomes an aerobic environment, but the inside becomes anaerobic, and a microenvironment in which nitrification and denitrification occur is allowed to coexist.
[0024]
Of these three types of nitrification / denitrification tanks 12, the circulation type shown in FIG. 2 (a) is particularly suitable for a large-scale or medium-scale treatment apparatus, and the alternating type shown in FIG. 2 (b). Since a device such as a timer is required for the product, it is suitable for a small-scale processing apparatus, and the coexistence type shown in FIG. 2 (c) slows down the reaction until reduction by coexisting the reaction. It is suitable for an extremely large-scale processing apparatus with a low load.
[0025]
As the solid-liquid separator 13, known devices such as a membrane separator, a decanter, and a filtration device are used.
The return path 14 is for returning the concentrated sludge separated from the supernatant liquid by the solid-liquid separator 13 to the anaerobic treatment 11, and is provided with a piping and pumping means (not shown) such as a pump for transporting the concentrated sludge. It is prepared.
[0026]
In addition, in the treatment cycle 15 including the anaerobic treatment tank 11, the nitrification denitrification tank 12, the solid-liquid separation device 13, and the return path 14, the introduced sludge is modified to be easily biodegradable. A leading reformer 16 is provided. In this example, the reformer 16 is provided in the return path 14, and therefore reforms the concentrated sludge produced in the nitrification denitrification tank 12 and then separated in the solid-liquid separator 13, and this is anaerobically treated. It returns to the tank 11.
[0027]
The reformer 16 may be an apparatus capable of reforming the introduced sludge to be readily biodegradable, such as an ozone treatment device, a hydrothermal treatment device, an alkali treatment device, a heat treatment device, an ultrasonic treatment device, and a pulse voltage treatment device. Any of them can be used, but the ozone treatment apparatus is particularly preferable because it has a high reforming effect. Therefore, in this example, an ozone treatment device is employed as the reforming device 16.
[0028]
In the reformer 16, sludge generated in the nitrification / denitrification tank 12, that is, sludge containing denitrification bacteria and nitrification bacteria is concentrated and introduced by the solid-liquid separator 13.
Here, in the nitrification denitrification tank 12, the number of cells increases due to the growth of microorganisms in the sludge, but even if the living cells are concentrated and sent to the anaerobic treatment tank 11, the volume can be reduced by digestion. There is a limit. However, when reforming is performed by ozone treatment or the like in the reforming device 16, the bacterial cells in the sludge are killed and decomposed together with other organic substances, and low-molecular organic substances and some inorganic substances are produced to easily biodissolve. To be modified.
[0029]
Therefore, when the sludge reformed by the reformer 16 is sent to the anaerobic treatment tank 11, the reformed sludge is utilized and decomposed as a substrate for anaerobic microorganisms. Therefore, the volume of sludge is reduced, and the amount of sludge discharged as excess sludge is reduced.
[0030]
Based on the processing method by the processing apparatus 10 having such a configuration, the organic drainage processing method of the present invention will be described.
First, an organic drainage liquid (SS (suspension) up to 25%) to be treated is introduced into the anaerobic treatment tank 11 from a liquid passage (not shown) and concentrated in a return passage 14. Anaerobic treatment with sludge. Then, by such anaerobic treatment, the organic matter is converted into digestion gas such as methane by the action of acid producing bacteria and methanogenic bacteria, that is, methane fermentation is performed, and the produced gas is released out of the system.
[0031]
Next, the mixture of the liquid component and the sludge generated by the anaerobic treatment in this way is introduced into the nitrification / denitrification tank 12 through a communication path (not shown) as a derived product. Then, the nitrification reaction is carried out by the action of nitrifying bacteria here, and the denitrification reaction is carried out by the action of denitrifying bacteria to carry out nitrification and denitrification treatment, whereby ammonium ions are nitrified to nitrite ions or nitrate ions, It is released out of the system by being reduced to nitrous oxide or nitrogen gas.
[0032]
Subsequently, the mixture of the liquid component and the sludge generated by the nitrification / denitrification process in this manner is introduced into the solid-liquid separator 13 as a derived product through a communication path (not shown). And solid-liquid separation is performed here, and the separated supernatant liquid is discharged | emitted from the processing apparatus 10 through a process liquid path (not shown). On the other hand, part or all of the separated concentrated sludge is introduced into the reformer 16 via the return path 14. Then, in the reformer 16, the introduced sludge is brought into contact with ozone, so that the sludge is reformed, that is, the cells in the sludge are killed and decomposed together with other organic substances, and low molecular organic substances and some of them An inorganic substance is produced and modified to be readily biosoluble.
[0033]
The sludge modified to be easily biosoluble in this manner is returned to the anaerobic treatment tank 11 as described above, and anaerobic treatment is performed together with newly introduced organic drainage. At this time, since the ammonia is removed from the modified sludge in the nitrification denitrification tank 12, when this is returned to the anaerobic treatment tank 11, the ammonia concentration in the anaerobic treatment tank 11 decreases. Increases the activity of methanogens.
And hereinafter, the treated product (sludge) obtained in each treatment step is circulated through the treatment cycle 15 including the reformer 16, and the treatment is performed in each, so that the introduced organic drainage is methane, A gas such as nitrogen or a supernatant liquid in the solid-liquid separator 13 is discharged out of the processing apparatus 10.
[0034]
Such an organic drainage treatment method includes a treatment cycle 15 comprising an anaerobic treatment step by the anaerobic treatment 11, a nitrification denitrification step by the nitrification denitrification tank 12, and a return step by the return path 14. Therefore, it is possible to remove the nitrogen compounds by treating the derived product from the anaerobic treatment process in the nitrification denitrification process, and return it to the anaerobic treatment process through the solid-liquid separation process and the reforming process. Therefore, the effect of volume reduction can be enhanced by preventing the methane fermentation from being inhibited by ammonia in the anaerobic treatment step and performing the anaerobic treatment satisfactorily.
[0035]
Further, by performing the nitrification / denitrification process in the nitrification / denitrification step, the amount of nitrogen in the supernatant liquid (treated water) discharged from the solid-liquid separator 13 can be sufficiently reduced. Therefore, when this supernatant liquid (treated water) is discharged into public water bodies, the [organic matter / N] ratio in this supernatant liquid (treated water) is increased, which greatly increases the burden of this post-treatment. Can be reduced. Further, depending on the nature of the introduced organic drainage and the degree of circulation in the treatment cycle 15, it is possible to purify the water so that it can be discharged into public water bodies without performing post-treatment.
[0036]
Furthermore, since the reforming step is included in the treatment cycle 15, the introduced sludge is modified to be easily biodegradable and derived, thereby reducing the volume of sludge generated in the entire treatment system. can do. In particular, since the sludge modified by the reformer 16 is returned to the anaerobic treatment tank 11, the anaerobic treatment in the anaerobic treatment tank 11 can be made highly efficient.
[0037]
Moreover, in the processing apparatus 10 of organic drainage, the said processing method can be implemented, Therefore The effect mentioned above can be show | played.
[0038]
Figure 3 Organic drainage in the present invention It is a schematic block diagram for demonstrating one Embodiment of the processing apparatus of this, and the code | symbol 20 in FIG. 3 is a processing apparatus of organic waste_water | drain. The organic waste liquid treatment device 20 is different from the treatment device 10 shown in FIG. 1 in that a solid-liquid separation device 21 is provided between the anaerobic treatment tank 11 and the nitrification denitrification tank 12. .
[0039]
This solid-liquid separation device 21 is of a known configuration such as a membrane separation device, a decanter, and a filtration device, like the solid-liquid separation device 13 disposed on the downstream side of the nitrification denitrification tank 12, and is an anaerobic treatment tank. The effluent from 11 is solid-liquid separated, the concentrated sludge is returned to the anaerobic treatment tank 11, and the supernatant is sent to the nitrification denitrification tank 12.
[0040]
In the processing apparatus 20 including such a solid-liquid separation device 21, the sludge generated in the anaerobic treatment tank 11 is solid-liquid separated by the solid-liquid separation apparatus 21, and the concentrated sludge is returned to the anaerobic treatment tank 11. Therefore, the anaerobic microorganism concentration in the anaerobic treatment tank 11 can be increased by quickly returning the sludge containing the anaerobic microorganisms to the anaerobic treatment tank 11. Therefore, in the processing apparatus 20, especially when the anaerobic treatment process in the anaerobic treatment tank 11 is rate-determining, the anaerobic treatment can be accelerated, whereby the entire process itself can be accelerated.
[0041]
In addition, since the processing can be speeded up in this way, the anaerobic processing tank 11 can be downsized if the processing speeds are made equal, and therefore suitable for a case where processing is particularly desired in a narrow space. It becomes.
In this processing apparatus 20, the concentrated sludge is returned to the anaerobic treatment tank 11 by the solid-liquid separator 21, but ammonia in the sludge generated in the anaerobic treatment tank 11 is dissolved in the supernatant after the solid-liquid separation. Therefore, the methane fermentation is also prevented from being inhibited by ammonia.
[0042]
Figure 4 Organic drainage in the present invention It is a schematic block diagram for demonstrating one Embodiment of the processing apparatus of this, and the code | symbol 30 in FIG. 4 is a processing apparatus of organic waste_water | drain. The organic waste liquid treatment device 30 is different from the treatment device 10 shown in FIG. 1 in that the reformer is not provided in the return path 14 but is provided between the anaerobic treatment tank 11 and the nitrification denitrification tank 12. It is a point.
[0043]
Under such a configuration, the treatment apparatus 30 reforms the derived product from the anaerobic treatment tank 11 with the reformer 16 and then sends it to the nitrification denitrification tank 12. Therefore, the nitrification denitrification tank 12, the introduced sludge is already easily biodegradable, and the sludge reformed by the reformer 16 serves as a carbon source for denitrification in the nitrification denitrification tank 12. Nitrogen reaction and nitrification reaction occur more rapidly, and this prevents the inhibition of methane fermentation by ammonia more reliably.
[0044]
In each of the above-described embodiments shown in FIGS. 1, 3, and 4, the place where the organic drainage is first introduced is the anaerobic treatment tank 11, but the present invention is not limited to this. It is not something. That is, in the treatment cycle 15 having the anaerobic treatment tank 11, the nitrification denitrification tank 12, and the reforming device 16, the first introduction destination of the organic waste liquid is the sign (a) in FIGS. As shown in (b) and (c), any one of the anaerobic treatment tank 11, the nitrification denitrification tank 12, and the reformer 16 may be used. The initial introduction destination of such organic drainage is selected according to the characteristics of the organic drainage to be introduced.
[0045]
FIG. 8 is a diagram showing a list of the relationship between the characteristics of organic drainage and its preferable first introduction destination. For example, when processing organic effluent (organic sludge) mainly composed of microbial cells, the efficiency of anaerobic treatment is low as it is (it is difficult for methane fermentation). Good. By introducing the organic effluent into the reformer first, the introduced organic effluent is easily biodegradable, and the efficiency of the anaerobic treatment in the anaerobic treatment tank is improved. Is possible.
[0046]
In addition, when treating organic drainage mainly composed of organic substances other than microorganisms (for example, livestock manure, brewing lees, etc.), it is efficiently treated anaerobically (easy to methane fermentation) as it is. As shown in the form, it may be first introduced into the anaerobic treatment tank.
[0047]
However, in this case, when the concentration of the organic drainage liquid is relatively low, the organic drainage liquid may be first introduced into the nitrification denitrification tank from the viewpoint of energy cost. That is, in an anaerobic tank, the inside of the tank is usually heated to a predetermined temperature range in order to prevent a decrease in the activity of anaerobic microorganisms. Therefore, when a low concentration organic waste liquid is introduced into the anaerobic treatment tank, the amount of organic matter contained in the organic waste liquid is small, so that the energy consumed for heating increases with respect to the amount of organic matter treated, Not energy efficient. On the other hand, the nitrification denitrification tank is characterized in that it can be treated even at a relatively low temperature and has high sludge conversion efficiency for converting the drainage into sludge. Therefore, by introducing low-concentration organic effluent to the nitrification denitrification tank first, the organic effluent is concentrated to improve the processing efficiency in the subsequent processes, and the energy cost of the entire processing cycle. Can be reduced. A plurality of organic processing liquids having different characteristics may be introduced from different locations in the same processing cycle according to the respective characteristics. Moreover, the selection criteria of the first introduction destination of the organic waste liquid demonstrated using FIG. 8 are an example, and this invention is not limited to this. The introduction destination of the organic drainage liquid can be appropriately selected according to various conditions such as the configuration of the apparatus and the processing time.
[0048]
Moreover, in each said embodiment shown in previous FIG.1, FIG.3 and FIG.4, the derived material from the nitrification denitrification tank 12 is solid-liquid-separated with the solid-liquid separator 13, and the sludge as solid content is made anaerobic. Although it returns to the processing tank 11 or the reformer 16, this invention is not limited to this. That is, in the treatment cycle 15 having the anaerobic treatment tank 11, the nitrification denitrification tank 12, and the reformer 16, as shown in FIGS. 5, 6, and 7, another return path 40 branched from the return path 14 is provided. It is also possible to provide at least a part of the derived product from the nitrification / denitrification tank 12 and return it to the nitrification / denitrification tank 12. In this case, it is possible to improve the removal rate of nitrogen compounds by returning at least a part of the derivation from the nitrification denitrification tank 12 to the nitrification denitrification tank 12 via the return path 40 and nitrifying denitrification again. It becomes.
[0049]
Here, although ozone treatment is adopted as the reforming treatment in the present invention, the effect of reforming by ozone after the anaerobic treatment was examined as follows.
The raw sludge was digested for 5 days (anaerobic treatment), the digested for 30 days (anaerobic treatment), and the raw sludge that was not digested (anaerobic treatment) were subjected to ozone treatment for a predetermined time. Then, the sludge after the ozone treatment was dehydrated by centrifugation, and the moisture content of the obtained cake was examined. FIG. 9 shows the relationship between the ozone treatment time and the moisture content of the cake.
[0050]
From FIG. 9, the moisture content of the cake subjected to the digestion treatment (anaerobic treatment) decreased as the ozone treatment time increased, whereas the raw moisture content slightly increased the cake moisture content. Therefore, it was confirmed that when the ozone treatment was performed on the digestion treatment (anaerobic treatment), the solid-liquid separation property could be improved.
[0051]
Next, in order to confirm the effect of the present invention, the material balance trial calculation results in the processing apparatuses 10, 20, 30 of the present invention shown in FIGS. 1, 3, and 4 and the conventional apparatus shown in FIG. Is shown in FIGS. As shown in FIG. 13, in the conventional apparatus shown in FIG. 17, a trial calculation was performed on the assumption that a post-treatment step 6 for performing nitrification denitrification was provided after the solid-liquid separation step 3.
[0052]
As shown in FIGS. 10 to 13, CODCr (chemical oxygen demand, by potassium dichromate method) is compared with the processing apparatuses 10, 20, 30 of the present invention and the conventional apparatus shown in FIG. 17, respectively. It is assumed that an organic effluent with a particularly high nitrogen concentration is introduced and treated, with a slag of 57700 mg / L, SS (suspension) of 59500 mg / L, and TN (total nitrogen) of 4400 mg / L. And in each apparatus, when the amount of sludge extracted as surplus sludge was made constant, the material balance of CODCr and TN was estimated, and the estimated result was shown in FIGS.
[0053]
As shown in FIGS. 10 to 12, in the treatment apparatuses 10, 20, and 30 of the present invention, the sludge that has been subjected to the nitrification / denitrification treatment in the nitrification / denitrification treatment tank 12 is circulated to the anaerobic treatment. 11, the nitrogen concentration (T-N) was about 3000 mg / L, and it was found that ammonia inhibition was suppressed.
Further, the TN concentration of the processing liquid (supernatant liquid) discharged from the solid-liquid separator 13 is estimated to be 150 mg / L, which is significantly lower than that of the conventional apparatus shown in FIG. It has been found that the burden of is greatly reduced.
[0054]
On the other hand, in the conventional apparatus shown in FIG. 13, since the sludge is concentrated in the circulation system by the anaerobic treatment process 1 and the reforming process 5, the TN concentration in the anaerobic treatment tank is the treatment liquid. It was estimated that the concentration of ammonium ion + ammonia would be higher than 2000 to 3000 mg / L, where inhibition of methanogen appears, which is higher than (supernatant) 4800 mg / L.
Further, even if this treatment liquid (supernatant liquid) is to be denitrified in the post-treatment step, the ratio of [CODCr / TN] is 2 or less, so that sufficient denitrification cannot be performed. It was estimated that the concentration was not reduced to 1600 mg / L.
[0055]
From these trial calculation results, the processing apparatuses 10, 20, and 30 of the present invention solve the problems caused by nitrogen compounds while taking advantage of the method of combining the reforming process with the anaerobic process of reducing excess sludge. Confirmed that you can.
[0056]
【The invention's effect】
As described above, since the organic waste liquid treatment method of the present invention is a method having a treatment cycle comprising an anaerobic treatment step, a nitrification denitrification step, and a return step, a derivative from the anaerobic treatment step. Can be removed in the nitrification and denitrification process, which can be returned to the anaerobic treatment process, thus preventing the methane fermentation from being inhibited by ammonia in the anaerobic treatment process, and anaerobic The effect of volume reduction can be enhanced by performing the treatment satisfactorily.
[0057]
Further, the amount of nitrogen in the treated water finally derived from the treatment system by passing through the nitrification and denitrification step can be sufficiently reduced. Therefore, when this treated water is discharged into public water areas, this treatment is performed. Since the [organic matter / N] ratio in water is increasing, the burden of this post-treatment can be greatly reduced. Further, depending on the nature of the introduced organic drainage and the degree of circulation in the treatment cycle, it is possible to purify the water so that it can be discharged into public water bodies without performing post-treatment. Therefore, the drainage treatment facility with a high nitrogen compound concentration in the organic drainage and the regulation of the discharge of the nitrogen compound is particularly effective.
Furthermore, since it has a reforming step in the treatment cycle, the introduced sludge is modified to be easily biodegradable and derived, thereby reducing the volume of sludge produced in the entire treatment system. be able to.
[0058]
Since the organic waste liquid treatment apparatus of the present invention can carry out the above treatment method, it is possible to prevent methane fermentation from being inhibited by ammonia in an anaerobic treatment tank, and in a post-process. It is possible to drastically reduce the burden on the wastewater, and to achieve excellent effects such as the ability to reduce the volume of sludge generated in the entire treatment system.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram for explaining a schematic configuration of an embodiment of an organic drainage treatment apparatus according to the present invention.
FIGS. 2A, 2B, and 2C are diagrams for explaining a specific configuration of a nitrification denitrification tank.
FIG. 3 is a diagram for explaining a schematic configuration of another embodiment of the organic waste liquid treatment apparatus of the present invention.
FIG. 4 is a diagram for explaining a schematic configuration of another embodiment of the organic waste liquid treatment apparatus of the present invention.
FIG. 5 is a diagram for explaining a schematic configuration of another embodiment of the organic waste liquid treatment apparatus of the present invention.
FIG. 6 is a view for explaining a schematic configuration of another embodiment of the organic drainage treatment apparatus of the present invention.
FIG. 7 is a view for explaining a schematic configuration of another embodiment of the organic waste liquid treatment apparatus of the present invention.
FIG. 8 is a diagram showing a list of relationships between characteristics of organic drainage and preferred introduction destinations thereof.
FIG. 9 is a graph showing the relationship between the ozone treatment time and the moisture content of the cake.
FIG. 10 is a diagram showing a trial calculation result of a material balance of the organic drainage treatment apparatus shown in FIG.
11 is a diagram showing a trial calculation result of a material balance of the organic drainage treatment apparatus shown in FIG.
12 is a diagram showing a trial calculation result of a material balance of the organic drainage treatment apparatus shown in FIG.
13 is a diagram showing a trial calculation result of a material balance of the organic drainage treatment apparatus shown in FIG.
FIG. 14 is a diagram for explaining a schematic configuration of an example of a conventional organic waste liquid treatment apparatus.
FIG. 15 is a diagram for explaining a schematic configuration of another example of a conventional organic waste liquid treatment apparatus.
FIG. 16 is a diagram for explaining a schematic configuration of another example of a conventional organic waste liquid treatment apparatus.
FIG. 17 is a diagram for explaining a schematic configuration of another example of a conventional organic waste liquid treatment apparatus.
[Explanation of symbols]
10, 20, 30 ... Organic drainage treatment device,
11 ... anaerobic treatment tank,
12 ... nitrification denitrification tank,
13 ... Solid-liquid separator,
14, 40 ... Return path,
15 ... processing cycle,
16 ... reformer,
21 ... Solid-liquid separator.

Claims (4)

Anaerobic treatment process in which organic effluent is methane-fermented in the presence of sludge containing anaerobic microorganisms, and nitrification and denitrification to remove nitrogen compounds by reaction of nitrification and denitrification to the products derived from the anaerobic treatment process A process cycle consisting of a process and a return process for returning the sludge generated in the nitrification denitrification process to the anaerobic process,
A reforming step that is provided during the return step for returning the sludge generated in the nitrification denitrification step to the anaerobic treatment step and that the introduced sludge is easily biodegradable and derived therefrom ;
Between the anaerobic treatment process and the nitrification denitrification process, the product derived from the anaerobic treatment process is separated into solid and liquid, the concentrated sludge is returned to the anaerobic treatment process, and the supernatant is sent to the nitrification denitrification process. An organic drainage treatment method comprising: a liquid separation step . 2. The method of treating organic drainage according to claim 1, wherein the returning step returns at least a part of the derived product from the nitrification / denitrification step to the nitrification / denitrification step . An anaerobic treatment tank for methane fermentation of organic effluent in the presence of sludge containing anaerobic microorganisms, and a nitrification denitrification tank for removing nitrogen compounds by reacting the effluent from the anaerobic treatment tank with nitrification and denitrification And a return path for returning the sludge generated in the nitrification denitrification tank to the anaerobic treatment tank, and a treatment cycle comprising:
A reformer that is provided in a return path for returning the sludge produced in the nitrification denitrification tank to the anaerobic treatment tank and that reforms the introduced sludge to be readily biodegradable;
  Solid-liquid separation between the anaerobic treatment tank and the nitrification denitrification tank, and the liquid derived from the anaerobic treatment tank is separated into solid and liquid, the concentrated sludge is returned to the anaerobic treatment tank, and the supernatant is sent to the nitrification denitrification tank. Equipment and
An organic drainage treatment apparatus characterized by comprising: 4. The organic drainage treatment apparatus according to claim 3, wherein a return path is provided for returning at least a part of the discharged product from the nitrification denitrification tank to the nitrification denitrification tank.

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