JP2007237055A - Organic waste water treatment method and arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic waste water treatment method which prevents a decrease in treatment performance and an increase in treatment cost of methane fermentation treatment facilities by loading it with the suitable amount of water even if the fluctuation of wastewater concentration is present, and an arrangement. <P>SOLUTION: The organic waste water treatment method anaerobically treating the organic wastewater by a methane fermentation tank 16 comprises the steps of obtaining the load of an inhibitor per the weight of a metanogen in the methane fermentation tank 16 from the weight of the metanogen in the methane fermentation tank 16, the concentration of the inhibitor for inhibiting methane fermentation and a flow rate per unit time of water to be treated flowing into this methane fermentation tank 16, determining a relation of a change in organic substance removal ratio in the methane fermentation tank of the water to be treated for each load of each inhibitor to the concentration of the above-described inhibitor when the load of this inhibitor is changed, and adjusting either or both of the load of dilution water loaded into the organic wastewater and the supply amount of this water to be treated to the methane fermentation tank 16 so as to provide the organic substance removal ratio of the methane fermentation tank 16 with a predetermined value using this relation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for treating organic wastewater, for example, anaerobically treating organic wastewater from food industry facilities and the like with a methane fermentation tank.

One method of treating organic wastewater is methane fermentation. Compared with anaerobic wastewater treatment methods such as activated sludge method, methane fermentation, which is an anaerobic wastewater treatment method, has advantages in terms of energy, such as no need for air supply and the use of generated biogas as fuel. is there. It is known that methane fermentation is inhibited by a specific substance (inhibitory substance) contained in wastewater (see, for example, Non-Patent Document 1). In order to prevent the reduction of methane fermentation performance due to inhibition, a method of diluting waste water to reduce the concentration of the inhibitory substance has been proposed (see, for example, Patent Document 1).
Water and wastewater: Vol.31 No.1 (1989) p.21-25 Japanese Patent Publication No. 2-18914

  However, the amount of wastewater that must be treated increases if water is added to the wastewater and diluted to reduce the concentration of the inhibitor. If the amount of wastewater increases, the capacity and installation area of the methane fermentation treatment facility will increase and the construction cost of the facility will increase. In addition, the power consumption necessary for the operation of the processing equipment increases and the maintenance cost of the equipment increases. Therefore, it is desirable that the amount of water added be low as long as the treatment is not affected.

  In addition, the concentration of wastewater may have seasonal fluctuations and time fluctuations. In this case, the concentration of the inhibitor contained in the wastewater also varies. Until now, since there is no clear knowledge about the relationship between the wastewater concentration, the inhibitory substance, and the amount of dilution water, conventionally, the amount of dilution water has been determined by trial and error based on empirical rules. For this reason, in order to perform the methane fermentation treatment reliably, the addition amount of dilution water is set in accordance with the highest wastewater concentration. As a result, when the wastewater concentration is low, the addition amount of water becomes excessive. There is a problem.

  An object of the present invention is to provide an organic wastewater treatment method and apparatus for adding an appropriate amount of water even when the concentration of wastewater varies, and preventing a reduction in treatment performance and an increase in treatment costs of the methane fermentation treatment facility. It is to provide.

  An organic wastewater treatment method according to the present invention is an organic wastewater treatment method in which organic wastewater is anaerobically treated with a methane fermentation tank, and the amount of methane bacteria in the methane fermentation tank and the methane fermentation tank flow into the methane fermentation tank. When the inhibitor load per unit weight of methane bacteria in the methane fermentation tank is determined from the concentration of the inhibitor that inhibits methane fermentation and the flow rate per unit time of the treated water, and this inhibitor load is changed The relationship of the change of the organic matter removal rate of the methane fermentation tank with respect to the inhibitor concentration of the water to be treated for each inhibitor loading amount is obtained in advance, and the organic matter removal rate of the methane fermentation tank is obtained using this relationship. The amount of dilution water added to the organic waste water to dilute the inhibitor in the treated water and the supply amount of the treated water to the methane fermentation tank Or by adjusting the both, and determines the inhibitor loading of the unit methane bacteria per weight of inhibitor concentration and the methane fermentation tank of the water to be treated.

  In the method of the present invention, the inhibitory substance is ammonia, and the ammonia concentration of the water to be treated and the ammonia load per unit methane bacteria weight in the methane fermentation tank are determined.

  Moreover, the organic wastewater treatment method for anaerobically treating the organic wastewater of the present invention with a methane fermentation tank includes the weight of methane bacteria in the methane fermentation tank, and the organic matter concentration of the treated water flowing into the methane fermentation tank. From the flow rate per unit time, obtain the organic matter load per unit methane bacteria weight, and when this organic matter load is changed, for each organic matter load, A relationship of change in organic matter removal rate is obtained in advance, and using this relationship, the organic matter in the treated water is added to the organic waste water so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value. Adjusting either or both of the amount of dilution water to be diluted and the amount of water to be treated to be supplied to the methane fermentation tank, the organic matter concentration of the water to be treated and Determining the object load.

  An apparatus for treating organic wastewater according to the present invention includes a diluted reservoir for adding dilution water to organic wastewater, and a water to be treated in the diluted reservoir to which dilution water is added. Inhibitor substance measuring means for measuring the substance concentration that inhibits methane fermentation, treated water supply device having a flow rate adjusting function for supplying treated water in this diluted storage tank to the methane fermentation tank, and the methane fermentation tank The inhibitory substance concentration is obtained by the provided methane bacteria weight measuring means and the inhibitory substance measuring means provided in the diluted storage tank, and the methane bacteria weight in the methane fermentation tank by the methane bacteria weight measuring means provided in the methane fermentation tank. The unit methane is obtained from the weight of methane bacteria in these methane fermenters, the concentration of the inhibitor in the treated water flowing into the methane fermenter, and the flow rate per unit time. When the inhibitor load per unit weight of the fungus is changed, the relationship of the change in the organic matter removal rate of the methane fermenter with respect to the inhibitor concentration of treated water for each inhibitor load is determined and set in advance. In addition, by using this set relationship, the amount of diluted water added to the organic wastewater in the diluted storage tank so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value, and this And a control device for adjusting either or both of the supply amount of the water to be treated to the methane fermentation tank.

  Further, in the organic wastewater treatment apparatus according to the present invention, the ammonia concentration measuring means is used as the inhibitor measuring means, and the control device is the ammonia concentration in the water to be treated flowing into the methane fermentation tank measured by the ammonia concentration measuring means. Of the organic matter removal rate of the methane fermenter with respect to the ammonia concentration of the water to be treated for each ammonia load when changing the ammonia load per unit methane bacteria weight, obtained from the flow rate per unit time Is obtained and set in advance, and is added to the organic wastewater in the diluted storage tank so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value using the set relation. Either or both of the addition amount of dilution water and the supply amount of this to-be-processed water to the methane fermentation tank are adjusted.

The processing apparatus of the organic waste water of Claim 4 characterized by the above-mentioned.

  In the organic wastewater treatment apparatus according to the present invention, an ammonia concentration may be obtained from the measured total nitrogen concentration by using a total nitrogen meter as the ammonia concentration measuring means.

  Furthermore, the organic wastewater treatment apparatus according to the present invention includes a diluted reservoir tank for adding dilution water to the organic wastewater, and a target to be treated in the diluted reservoir tank provided in the diluted reservoir tank and added with the dilution water. SS meter for measuring suspended substances in water, treated water supply device having a flow rate adjusting function for supplying treated water in the diluted storage tank to the methane fermentation tank, SS meter provided in the methane fermentation tank, The organic matter concentration of the water to be treated is obtained from the sludge interface meter and the SS meter value provided in the diluted reservoir tank, and the methane bacteria in the methane fermentation tank are obtained from the SS meter and the sludge interface meter provided in the methane fermentation tank. The amount of organic matter loaded per unit methane bacterium weight obtained from the methane bacterium weight in these methane fermenters, the organic matter concentration of the treated water flowing into this methane fermenter, and the flow rate per unit time can be changed. For each organic matter load amount, the relationship of the change in the organic matter removal rate of the methane fermentation tank with respect to the organic matter concentration of the water to be treated is determined and set in advance, and using this set relationship, The amount of diluted water added to the organic wastewater in the diluted storage tank and the supply amount of the treated water to the methane fermentation tank so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value. A configuration including a control device that adjusts either or both may be used.

  According to the present invention, the amount of diluted water added can be reduced so that the inhibitor load or the organic load of the methane fermenter is reduced to such an extent that it does not lead to a decrease in the organic matter removal efficiency that is the methane fermentation performance. In addition, the amount of dilution water added can be minimized, and the organic wastewater can be anaerobically treated without causing deterioration in methane fermentation performance.

  Hereinafter, an embodiment of an organic wastewater treatment method and apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 illustrates the basic concept of the present invention. Experiments were performed using this apparatus configuration, and the knowledge shown in FIG. 2 was obtained. Here, the experiment was conducted on the assumption that the concentration of the inhibitor for anaerobic treatment and the organic matter concentration of the organic wastewater have a correlation.

  In FIG. 1, reference numeral 11 denotes a raw water tank for storing organic waste water (hereinafter referred to as raw water), and the raw water is supplied to the diluted storage tank 13 by a pump 12. The diluted reservoir tank 13 dilutes the raw water sent from the raw water tank 11 by adding the diluted water in the water tank 14 with the pump 15 to be treated in the subsequent methane fermentation tank 16 (hereinafter, diluted waste water). To be stored). Diluted wastewater (treated water) in the diluted reservoir tank 16 is supplied to the methane fermentation tank 16 by the pump 17, subjected to methane fermentation treatment by methane bacteria in the methane fermentation tank 16, and discharged as treated water.

  The relationship between the organic matter concentration of diluted wastewater in such equipment, the organic matter load of the methane fermentation tank 16 and the organic matter removal rate of the methane fermentation tank 16 was investigated. As the organic matter concentration of the diluted wastewater, chemical oxygen demand (hereinafter referred to as COD) was used. The amount of organic substances loaded in the methane fermentation tank 16 was determined by the amount of organic substances flowing into the methane fermentation tank per unit time per unit methane bacteria weight (organic substance concentration × inflow rate). The organic matter removal rate was determined from the COD of the treated water treated in the methane fermentation tank 16 and the COD of the diluted waste water before the treatment.

  When this experimental result was arranged, the knowledge shown in FIG. 2 was obtained. FIG. 2 shows the relationship between the organic matter removal rate of the methane fermenter 16 and the organic matter concentration of the diluted wastewater for each organic matter load when the organic matter load on the methane fermenter 16 is changed to low, medium, and high. Is shown. As is clear from the figure, when the organic matter load on the methane fermenter 16 is low, the organic matter concentration of the diluted wastewater has little effect on the organic matter removal rate of the methane fermenter 16. However, when the organic matter load of the methane fermentation tank 16 was increased, the organic matter removal rate of the methane fermentation tank 16 decreased as the organic substance concentration of the diluted wastewater increased.

  Thus, it was found that the performance (= organic matter removal rate) of the methane fermenter 16 is affected by the organic matter load of the methane fermenter 16 and the organic matter concentration of the diluted wastewater.

  Therefore, using the relationship shown in FIG. 2, the amount of diluted water added to the organic waste water so that the organic matter removal rate of the methane fermentation tank 16 becomes a predetermined value (a value that does not cause performance degradation); Either or both of the diluted wastewater supplied to the methane fermentation tank are adjusted to determine the organic matter concentration of the water to be treated and the organic matter load per methane bacterium weight. From this, the addition amount of dilution water can be reduced so that the amount of organic matter load may fall to the extent which does not lead to the fall of the organic matter removal efficiency which is methane fermentation performance. Therefore, the amount of dilution water added can be minimized, and the organic wastewater can be anaerobically treated without causing deterioration in methane fermentation performance.

  Based on the above basic concept, a system configuration when applied to an actual water treatment system will be described with reference to FIG. 3 also has the raw water tank 11, the diluted storage tank 13, and the methane fermentation tank 16 as in FIG. 1, and further includes the diluted water tank 14 and the pumps 12, 15, and 17 as equipment related thereto. Shall. The raw water tank 11, the diluted storage water tank 13, and the methane fermentation tank 16 are provided with suspended matter (SS) meters (hereinafter referred to as SS meters) 21, 22, and 23, respectively. These SS meters 21, 22, 23 measure the SS values of the corresponding tanks 11, 13, 16 and output them to the control device 25, respectively.

  In general, the SS value and the COD are expected to have high correlation, so the SS value can be used as an alternative value for the COD. That is, by creating a correlation equation by experiment in advance and setting it in the control device 25, the COD can be obtained from the SS values measured by the SS totals 21, 22, and 23.

  The methane fermentation tank 16 is provided with a sludge interface meter 24 to measure the sludge interface value of the methane fermentation tank 16. From the measured sludge interface height and the volume (known value) of the methane fermentation tank 16, the sludge volume in the methane fermentation tank 16, that is, the apparent volume of methane bacteria can be obtained. Then, from the volume value and the SS value of the methane fermentation tank 16, the weight of methane bacteria in the methane fermentation tank 16 is obtained. Therefore, the SS meter 23 and the sludge interface meter 24 function as methane gold weight measuring means.

  The flow rates of a pump (hereinafter referred to as a waste water pump) 12 for supplying raw water (organic waste water) to the diluted reservoir tank 13 and a pump (hereinafter referred to as a water pump) 15 for supplying diluted water to the diluted reservoir tank 13 are as follows. By adjusting, the organic substance density | concentration of the dilution wastewater in the dilution storage water tank 13 is adjusted. Moreover, the organic substance load amount to the methane fermentation tank 16 can be adjusted by adjusting the flow rate of a pump (hereinafter referred to as a diluted wastewater pump) 17 that supplies the diluted wastewater to the methane fermentation tank 16. Here, the diluted wastewater pump 17 functions as a to-be-treated water supply device having a flow rate adjusting function for supplying the diluted wastewater (treated water) in the diluted reservoir tank 13 to the methane fermentation tank 16.

  In such equipment, the relationship corresponding to FIG. 2 is obtained in advance by experiments. That is, the organic substance concentration obtained by converting the SS value of the diluted reservoir tank 13, the methane bacteria weight contained in the methane fermentation tank 16 obtained from the SS value of the methane fermentation tank 16 and the sludge interface value, and the methane fermentation tank 16 Obtain the organic matter removal rate. The control device 25 determines the organic matter per weight of the methane bacterium from the weight of the methane bacterium in the methane fermentation tank 16 and the organic matter concentration and the flow rate per unit time of the diluted wastewater (treated water) flowing into the methane fermentation tank 16. Find the load. Then, as shown in FIG. 2, the relationship between the change in the organic matter removal rate of the methane fermentation tank 16 with respect to the organic matter concentration of the diluted wastewater for each organic matter load when the organic matter load is changed is determined and set in advance. Keep it.

  Based on this relationship, the control device 25 controls the water supply pump 15 so that the organic substance concentration converted from the SS value of the diluted reservoir tank does not decrease the organic substance removal rate of the methane fermentation tank 16 and adds the dilution water. Thus, by adjusting the addition amount of dilution water according to the organic substance load supplied to the methane fermentation tank 16, methane fermentation performance does not fall and the addition amount of water is suppressed to the minimum.

  Further, in the configuration of FIG. 3, when the amount or concentration of wastewater becomes very large and the required amount of water cannot be added, the organic load of the methane fermentation tank 16 decreases the methane fermentation performance based on the relationship of FIG. By reducing the flow rate of the diluted wastewater pump 17 so as to decrease to an extent that it does not connect, it is possible to prevent a decrease in methane fermentation performance.

  That is, the amount of diluted water added to the organic waste water and the amount of the diluted waste water (treated water) supplied to the methane fermentation tank 16 so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value. By adjusting either or both, the organic matter concentration of the water to be treated and the organic matter load per unit weight of the methane bacteria can be determined to minimize the addition amount of dilution water and reduce the methane fermentation performance. Organic wastewater can be anaerobically treated without being generated.

  In the above-described embodiment, the concentration of an inhibitor for anaerobic treatment and the organic matter concentration of organic wastewater have a correlation. The COD is obtained from the value. Of course, if the inhibitor concentration can be measured, it can be similarly implemented by using the inhibitor concentration instead of the organic concentration. That is, if the relationship shown in FIG. 2 is obtained in advance from the inhibitor concentration of diluted wastewater (treated water) and the amount of inhibitory substance per methane bacteria weight in the methane fermentation tank, the amount of dilution water added is minimized. The organic wastewater can be anaerobically treated without causing a decrease in methane fermentation performance.

  Here, it is known from the literature M. HENZE and P. HARREMOES: Wat. Sci. Tech. Vo. 15, p.23 that ammonia contained in wastewater inhibits methane fermentation. Since the ammonia measuring means is technically established, when it is known that ammonia in wastewater is the main factor of inhibition, instead of the SS meter of the raw water tank 11 and the dilution storage tank 13 in FIG. As shown in FIG. 4, ammonia measuring means 31 and 32 may be provided as inhibitor measuring means. As the ammonia measuring means 31 and 32, a commercially available ammonia meter or total nitrogen meter may be used.

  In this case, if the relationship shown in FIG. 2 is obtained in advance from the ammonia concentration of diluted wastewater (treated water) and the ammonia load per methane bacteria weight in the methane fermentation tank 16, the amount of dilution water added is the minimum necessary. The organic wastewater can be anaerobically treated without causing a decrease in methane fermentation performance.

It is a conceptual block diagram explaining the fundamental view of the processing method and apparatus of the organic wastewater by this invention. It is a characteristic view showing the relationship between the organic matter load of the methane fermenter used in one embodiment of the present invention, the organic matter concentration of treated water, and the organic matter removal rate of the methane fermenter. It is a system block diagram which shows one Embodiment of the processing apparatus of the organic waste water by this invention. It is a system block diagram which shows other embodiment of the processing apparatus of the organic waste water by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Dilution | reservation water tank 14 Dilution water tank 16 Methane fermentation treatment tank 17 Treated water supply apparatus 21,22,23 SS meter 24 Sludge interface meter 25 Controller 31,32 Ammonia measuring means

Claims (7)

An organic wastewater treatment method for anaerobically treating organic wastewater with a methane fermentation tank,
From the weight of methane bacteria in the methane fermentation tank and the concentration of the inhibitory substance that inhibits methane fermentation and the flow rate per unit time of the treated water flowing into the methane fermentation tank, the weight per unit methane bacteria in the methane fermentation tank Find the inhibitor loading,
For each inhibitor load amount when this inhibitor load amount is changed, the relationship between the change in the organic matter removal rate of the methane fermenter with respect to the inhibitor concentration of the treated water is obtained in advance,
Using this relationship, the amount of diluted water added to the organic wastewater to dilute the inhibitor in the treated water so that the organic matter removal rate of the methane fermenter becomes a predetermined value, Adjusting either or both of the amount of treated water supplied to the methane fermentation tank and determining the inhibitory substance concentration in the treated water and the amount of inhibitor load per unit methane bacteria weight in the methane fermentation tank A method for treating organic wastewater.   The method for treating organic wastewater according to claim 1, wherein the inhibitory substance is ammonia, and the ammonia concentration of the water to be treated and the ammonia load per unit methane bacteria weight in the methane fermentation tank are determined. An organic wastewater treatment method for anaerobically treating organic wastewater with a methane fermentation tank,
From the weight of methane bacteria in the methane fermentation tank and the concentration of organic matter and the flow rate per unit time of the water to be treated flowing into the methane fermentation tank, the amount of organic matter loaded per unit methane bacteria weight is determined,
When this organic matter load amount is changed, for each organic matter load amount, the relationship of the change in the organic matter removal rate of the methane fermentation tank with respect to the organic matter concentration of the water to be treated is obtained in advance.
Using this relationship, the amount of diluted water added to dilute the organic matter in the treated water added to the organic waste water and the treated so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value Either or both of the water supply to the methane fermenter is adjusted to determine the organic matter concentration of the water to be treated and the amount of organic matter loaded per unit methane bacterium weight. Method. A diluted reservoir for adding dilution water to organic waste water;
Inhibitory substance measuring means for measuring the substance concentration that inhibits methane fermentation in the treated water in the diluted storage tank to which dilution water is added, provided in this diluted storage tank,
A to-be-treated water supply device having a flow rate adjusting function for supplying the to-be-treated water in this diluted storage tank to the methane fermentation tank,
Methane weight measurement means provided in the methane fermentation tank,
The inhibitor concentration measuring means provided in the diluted storage tank is used to determine the inhibitor concentration, the methane bacteria weight measuring means provided in the methane fermentation tank is used to determine the methane bacteria weight in the methane fermentation tank, and the methane bacteria in these methane fermentation tanks. Each inhibitor loading amount when the inhibitor loading amount per unit methane bacteria weight obtained from the weight and the inhibitor concentration in the treated water flowing into the methane fermentation tank and the flow rate per unit time is changed. For each treated water, the relationship of the change in the organic matter removal rate of the methane fermentation tank with respect to the inhibitor concentration is determined in advance, and the organic matter removal rate of the methane fermentation tank is determined using this set relationship. Either the addition amount of dilution water added to the organic wastewater in the dilution reservoir and the supply amount of the treated water to the methane fermentation tank so as to have a predetermined value Processor of organic waste water, characterized in that a control device for adjusting both.   The ammonia concentration measuring means is used as the inhibitor measuring means, and the control device is a unit methane bacterium determined from the ammonia concentration in the treated water flowing into the methane fermentation tank measured by the ammonia concentration measuring means and the flow rate per unit time. When the ammonia load per weight is changed, the relationship of the change in the organic matter removal rate of the methane fermentation tank with respect to the ammonia concentration of the water to be treated for each ammonia load is determined and set in advance. Using the relationship, the amount of diluted water added to the organic wastewater in the diluted storage tank and the methane of the treated water so that the organic matter removal rate of the methane fermentation tank becomes a predetermined value. Either or both of the supply amount to a fermenter are adjusted, The processing apparatus of the organic wastewater of Claim 4 characterized by the above-mentioned.   The apparatus for treating organic wastewater according to claim 5, wherein the ammonia concentration is obtained from the measured total nitrogen concentration by using a total nitrogen meter as the ammonia concentration measuring means. A diluted reservoir for adding dilution water to organic waste water;
An SS meter that is provided in the diluted storage tank and measures suspended substances of the water to be treated in the diluted storage tank to which the diluted water is added,
A to-be-treated water supply device having a flow rate adjusting function for supplying the to-be-treated water in this diluted storage tank to the methane fermentation tank,
SS meter and sludge interface meter provided in the methane fermentation tank,
Obtain the organic matter concentration of the water to be treated from the value of the SS meter provided in the diluted storage tank, obtain the weight of methane bacteria in the methane fermentation tank from the value of the SS meter and sludge interface meter provided in the methane fermentation tank, and these Each organic matter when changing the organic matter load per unit methane bacteria weight obtained from the methane bacteria weight in the methane fermentation tank, the organic matter concentration of the treated water flowing into this methane fermentation tank and the flow rate per unit time For each load amount, the relationship of the change in the organic matter removal rate of the methane fermentation tank with respect to the organic matter concentration of the water to be treated is determined in advance and set, and using this set relationship, the organic matter removal rate of the methane fermentation tank Adjust either or both of the amount of dilution water added to the organic wastewater in the dilution reservoir and the amount of water to be treated to be supplied to the methane fermentation tank so that the value becomes a predetermined value. That the controller and the processor of organic wastewater comprising the.

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