JP2007190489A - Waste treatment method and waste treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste treatment method and a waste treatment system stably and efficiently treating waste at low cost. <P>SOLUTION: In this waste treatment method, waste is weighed for every component contained in the waste; solvent is added to the waste to obtain a total nitrogen concentration to impart ammonia nitrogen concentration within an allowable range in methane fermentation, based on the component-wise weight and nitrogen content in each component; and the total nitrogen concentration of a mixture containing the waste is adjusted, to perform methane fermentation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a waste treatment method and a waste treatment system. More particularly, the present invention relates to a waste treatment method and a waste treatment system based on methane fermentation.

  Currently, in the treatment of waste, attempts are being made to reduce the environmental impact and effective use of resources. For example, in the case of the treatment of solid organic waste such as garbage, the organic matter in the waste is decomposed by methane fermentation, methane gas is generated, and the methane gas is used as a resource. However, ammonia produced during methane fermentation has a drawback that the progress of methane fermentation is hindered and the efficiency of waste treatment may be reduced.

As a waste treatment method by methane fermentation that avoids inhibition of methane fermentation by ammonia, for example, a mixed solution in which solid organic waste is solubilized in a slurry state is subjected to methane fermentation treatment at pH 7.0 to 8.5. A waste processing method is known in which the generated gas is recovered, ammonia is removed from at least a portion of the recovered gas, and at least a portion of the gas from which ammonia has been removed is jetted into the liquid mixture and stirred. (For example, see Patent Document 1).
JP 2001-276880 A

  However, the waste treatment method requires equipment for removing ammonia, chemicals, etc., which increases equipment costs and operation costs, and may require a lot of labor in maintenance management. However, there is a drawback that it may be necessary.

  The present invention has been made in view of the above-described conventional drawbacks, and it is an object of the present invention to provide a waste treatment method capable of stably and efficiently treating waste at a low cost. And Another object of the present invention is to provide a waste treatment system capable of stably and efficiently treating waste at a low cost.

The present invention has been made in view of the above problems, and in one aspect, waste is measured for each component contained in the waste, and the weight of each component and the nitrogen contained in each component are measured. Based on the content, a solvent is added to the waste to adjust the total nitrogen concentration of the mixture containing the waste to a total nitrogen concentration that gives an acceptable ammoniacal nitrogen concentration in methane fermentation, and methane The present invention relates to a waste treatment method characterized by performing fermentation. In another aspect, the present invention provides a waste weight weighing means for weighing the waste for each component;
Based on the weight of each component weighed by the waste weight weighing means and the nitrogen content of each component, the appropriate amount of solvent for the waste that gives the ammonia nitrogen concentration within the allowable range of methane fermentation is calculated. A dilution solvent amount calculating means;
A waste accumulation facility for accumulating waste after being weighed by the waste weight weighing means;
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, dilution solvent injection means for introducing the dilution solvent into the waste,
A methane fermentation tank for subjecting the mixture mixed with the dilution solvent to methane fermentation,
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, the dilution solvent is mixed with the waste by the dilution solvent input means, so that the waste is ammonia within the allowable range of methane fermentation. The present invention relates to a waste treatment system characterized in that it is configured to be adjusted to a total nitrogen concentration that gives a neutral nitrogen concentration and the resulting mixture is introduced into the methane fermentation tank and used for methane fermentation.

  According to the waste treatment method of the present invention, appropriate conditions can be maintained during methane fermentation, and methane fermentation can be performed stably, so that waste can be treated stably and efficiently. Has an effect.

  Further, according to the waste treatment system of the present invention, in the appropriate dilution solvent amount calculation means, based on the weight of each component measured by the waste weight measurement means and the nitrogen content of each component, the allowable methane fermentation is allowed. Since the amount of the appropriate dilution solvent for the waste giving the ammonia nitrogen concentration in the range is calculated, the concentration of ammonia is higher than when measuring and adjusting the concentration of ammonia nitrogen generated during methane fermentation Can be prevented in advance, and there is an excellent effect that conditions suitable for methane fermentation can be obtained stably. Therefore, according to the waste treatment system of the present invention, since it has such a configuration, there is an excellent effect that a stable and efficient waste treatment can be performed. Furthermore, according to the waste treatment system of the present invention, the dilution solvent is mixed with the waste by the dilution solvent charging means based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means. Therefore, it is possible to maintain conditions suitable for methane fermentation by introducing a dilution solvent, for example, trapping ammonia nitrogen generated as a gas, maintaining the environment in the methane fermentation tank, etc. are substantially unnecessary, and waste can be easily There is an excellent effect that the process can be performed. Further, according to the waste treatment system of the present invention, the waste weight measuring means for weighing the waste for each component, the weight for each component measured by the waste weight measuring means, and the nitrogen for each component And a proper dilution solvent amount calculating means for calculating an appropriate dilution solvent amount for the waste that gives an ammoniacal nitrogen concentration in an allowable range of methane fermentation based on the content, so that the waste in a predetermined time unit It is possible to easily grasp the change in the weight of the components contained in the slag and to easily cope with the change in the total nitrogen content accompanying the change in the composition of the waste. Therefore, according to the waste treatment system of the present invention, there is an excellent effect that the waste treatment process can be more accurately automated.

  In one aspect, the present invention measures the waste for each component contained in the waste, and based on the weight of each component and the content of nitrogen contained in each component, the allowable range in methane fermentation A waste is characterized by adding a solvent to the waste so as to give a total nitrogen concentration that gives an ammoniacal nitrogen concentration, adjusting the total nitrogen concentration of the mixture containing the waste, and performing methane fermentation It relates to the processing method.

  The waste treatment method of the present invention has one major feature in that the weight of each component of the waste is measured. Therefore, according to the waste treatment method of the present invention, it is possible to more accurately grasp factors that affect the management of ammonia nitrogen concentration during methane fermentation, such as the amount of high nitrogen-containing components. Show the effect. Furthermore, according to the waste treatment method of the present invention, since the weight of each component of the waste is measured, the change in the component composition of the waste discarded in a predetermined time unit is more accurately grasped and dealt with. It exhibits the excellent effect of being able to.

  Furthermore, the waste treatment method of the present invention adds a solvent to the waste based on the weight of each component contained in the waste and the content of nitrogen contained in each component. One major feature is that the total nitrogen concentration of the mixture is adjusted. Therefore, according to the waste treatment method of the present invention, an excellent effect is achieved in that it is possible to stably maintain conditions suitable for methane fermentation easily and with higher accuracy. Therefore, according to the waste treatment method of the present invention, the excellent effect that the waste can be treated stably and efficiently is exhibited. In addition, such accuracy is significantly higher in methane fermentation than in the conventional methane fermentation performed using a slurry formed on the basis of the total weight of the waste, and the waste treatment of the present invention. The method is superior in that the conditions suitable for methane fermentation can be maintained more stably.

  In the present specification, the solvent may be referred to as a “dilution solvent”. Examples of the diluting solvent include water (for example, industrial water, treated water having a low nitrogen component concentration discharged from a wastewater treatment apparatus), and the like.

More specifically, the waste treatment method of the present invention is as follows.
(A) measuring the weight of the waste for each component;
(B) Based on the weight of each component weighed in step (A) and the content of nitrogen contained in each component, the total nitrogen content of the waste is calculated, and from the total nitrogen content Calculating an appropriate amount of diluting solvent that maintains an acceptable ammoniacal nitrogen concentration for methane fermentation;
(C) The diluted solvent is mixed with the waste weighed in (A) so that the amount of the appropriate diluted solvent calculated in the step (B) is obtained, and the total nitrogen concentration of the obtained mixture is changed to methane. Adjusting the concentration to give an acceptable ammoniacal nitrogen concentration in fermentation, and (D) subjecting the mixture obtained in step (C) to methane fermentation,
Is performed by a process including:

  In the present invention, the target waste may be, for example, waste that is subjected to methane fermentation, and examples thereof include organic waste such as garbage. The waste may contain components that are not subject to decomposition or the like by methane fermentation. In this case, components that are not subject to decomposition or the like by methane fermentation may be removed in advance from the waste before methane fermentation, or may be removed after methane fermentation.

  In the step (A), the weight of the waste is weighed for each component.

  The step (A) may be performed in units of a predetermined time according to the waste disposal capacity. Thereby, the composition, weight, etc. of the waste processed by one waste processing can be grasped more appropriately.

  When the waste treatment method of the present invention is applied to, for example, the treatment of waste in a manufacturing factory for foods and the like, the components of waste materials discarded by each manufacturing department are usually almost constant in the manufacturing factory. In many cases, in step (A), the nitrogen content of the waste can be easily grasped by measuring the weight of each waste disposed from each manufacturing department. In such a case, measuring the weight for each waste in each manufacturing department is synonymous with measuring for each component.

  Next, in step (B), based on the weight of each component weighed in step (A) and the nitrogen content contained in each component, the total nitrogen content of the waste is calculated, From the total nitrogen content, an appropriate dilution solvent amount that maintains an ammoniacal nitrogen concentration within an allowable range of methane fermentation is calculated.

  In the step (B), first, the total nitrogen content contained in the waste is determined based on the information on the weight of each component measured in the step (A) and the content of nitrogen contained in each component. Calculated. Thereby, it is possible to grasp the total nitrogen content contained in the waste corresponding to the change in the components of the waste in a predetermined time unit.

  Further, in the step (B), the amount of ammoniacal nitrogen that is predicted to be generated during methane fermentation is calculated from the calculated total nitrogen content. Here, the amount of ammoniacal nitrogen can be calculated with higher accuracy by taking into account the state of nitrogen contained in each component.

  Thereafter, in the step (B), an appropriate amount of diluting solvent that maintains the ammonia nitrogen concentration within the allowable range of methane fermentation is calculated from the predicted amount of ammonia nitrogen.

  In the step (B), the amount of water contained in each component can be considered.

  The ammonia nitrogen concentration within the allowable range of methane fermentation varies depending on the operating conditions of methane fermentation, the type of microorganism used, and the like. For example, in the case of high temperature (for example, 53 to 55 ° C.) methane fermentation, the ammoniacal nitrogen concentration within the allowable range of the methane fermentation is preferably about 2000 mg / l at the maximum, and medium temperature (for example, 36 to 55 ° C.). In the case of methane fermentation, it is desirable that the maximum is 4000 mg / l.

  In the present specification, the “appropriate dilution solvent amount” means the amount of ammonia nitrogen that is predicted to be generated during methane fermentation from the calculated total nitrogen content, and the amount of ammonia nitrogen in the allowable range of methane fermentation. It means the amount of diluting solvent required to reach a concentration.

  Thereafter, in the step (C), the diluted solvent is mixed with the waste weighed in the step (A) so that the amount of the appropriate diluted solvent calculated in the step (B) is obtained, and the resulting mixture is obtained. The total nitrogen concentration is adjusted to a concentration that gives an acceptable ammoniacal nitrogen concentration in methane fermentation.

  In the step (C), the diluting solvent is mixed with the waste weighed in the step (A). Therefore, in this step (C), the diluting solvent is added to the waste so that the amount of the diluting solvent becomes an appropriate amount corresponding to the composition of the waste weighed in the step (A).

  The addition of the diluting solvent to the waste can be performed by, for example, diluting solvent feeding means for feeding the diluting solvent to the waste based on the appropriate amount of the diluting solvent calculated in step (B). The dilution solvent charging means may include an automatic valve configured to control the addition amount of the dilution solvent to the waste in association with the appropriate dilution solvent amount calculated in the step (B). After the dilution solvent is added to the waste, the waste and the dilution solvent are mixed with, for example, a stirrer.

  After the step (C), in the step (D), the mixture obtained in the step (C) is subjected to methane fermentation. In the step (D), the mixture whose concentration is adjusted so that the total nitrogen concentration gives an ammoniacal nitrogen concentration within an allowable range in methane fermentation is subjected to methane fermentation. Therefore, in the waste treatment method of the present invention, the progress of methane fermentation is stably maintained.

  The methane fermentation can be performed using a conventional methanogenic microorganism or the like.

  The methane fermentation is performed in units of waste measured in step (A). Therefore, since the allowable ammonia nitrogen concentration adjusted according to the composition of the waste weighed in the step (A) is maintained, the inhibition of methane fermentation based on the ammonia nitrogen in an amount outside the allowable range is substantially prevented. Therefore, methane fermentation is performed stably and efficiently.

The waste treatment method of the present invention includes, for example, a waste weight weighing means for weighing the waste for each component,
Based on the weight of each component weighed by the waste weight weighing means and the nitrogen content of each component, the appropriate amount of solvent for the waste that gives the ammonia nitrogen concentration within the allowable range of methane fermentation is calculated. A dilution solvent amount calculating means;
A waste accumulation facility for accumulating waste after being weighed by the waste weight weighing means;
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, dilution solvent injection means for introducing the dilution solvent into the waste storage facility;
A methane fermentation tank for subjecting the mixture in which the diluent solvent is mixed in the waste accumulation facility to methane fermentation,
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, the dilution solvent is introduced into the waste storage facility by the dilution solvent input means, and the waste accumulated in the waste storage facility Mixed, whereby the waste is adjusted to a total nitrogen concentration that gives an acceptable ammoniacal nitrogen concentration for methane fermentation, and the resulting mixture is introduced into the methane fermenter and subjected to methane fermentation It can be suitably implemented by a waste treatment system characterized by being configured as described above.

  Therefore, in another aspect, the present invention relates to the waste treatment system.

  The waste treatment system of the present invention has a waste weight measurement means and an appropriate dilution solvent amount calculation means, and the waste weight measurement means and the appropriate dilution solvent amount calculation means calculate the appropriate dilution solvent amount. In the means, based on the weight of each component weighed by the waste weight weighing means and the nitrogen content of each component, there is an appropriate amount of diluting solvent for the waste that gives an ammonia nitrogen concentration within an allowable range of methane fermentation. One major feature is that it is configured to be calculated. Therefore, according to the waste treatment system of the present invention, by having such a configuration, it is possible to maintain methane fermentation more stably than when measuring and adjusting the concentration of ammonia nitrogen generated during methane fermentation. It is possible to obtain conditions suitable for methane fermentation with high accuracy. Further, according to the waste treatment system of the present invention, by having such a configuration, stable and efficient waste treatment can be performed.

  Furthermore, according to the waste treatment system of the present invention, there is provided an appropriate dilution solvent amount calculation means, a dilution solvent input means, and a waste storage facility, and the appropriate dilution solvent amount calculation means and the dilution solvent input means. And the waste storage facility, based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, the dilution solvent is introduced into the waste storage facility by the dilution solvent input means, Another great feature is that it is configured to be mixed with the waste accumulated in the waste accumulation facility. Therefore, according to the waste treatment system of the present invention, by having such a configuration, conditions suitable for methane fermentation can be maintained by introducing a diluent solvent, for example, ammonia such as stripping of ammonia nitrogen generated as a gas. It is not necessary to maintain the environment in the methane fermentation tank by removal, and waste can be treated easily and with low energy.

  Further, according to the waste treatment system of the present invention, since the waste weight measuring means and the appropriate dilution solvent amount calculating means are provided, the weight of the component contained in the waste in a predetermined time unit is obtained. The fluctuation can be easily grasped, and the fluctuation of the total nitrogen content accompanying the fluctuation of the composition of the waste can be easily dealt with. Therefore, according to the waste treatment system of the present invention, it is possible to accurately automate the waste treatment process so that the waste treatment process can be performed more efficiently.

  An example of the embodiment of the waste treatment system of the present invention is, for example, the waste treatment system shown in FIG. Hereinafter, the waste treatment system of the embodiment shown in FIG. 1 will be described as an example, but the present invention is not limited to such an embodiment.

The waste treatment system shown in FIG. 1 includes a waste weight weighing means 1 for weighing the waste for each component,
Based on the weight of each component weighed by the waste weight weighing means 1 and the nitrogen content of each component, the appropriate amount of the diluting solvent for the waste that gives the ammonia nitrogen concentration within the allowable range of methane fermentation is calculated. Dilution solvent amount calculating means 2;
A waste accumulation facility 3 for accumulating waste after being weighed by the waste weight weighing means 1;
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means 2, the dilution solvent injection means 4 that supplies the dilution solvent to the waste storage facility 3,
A methane fermentation tank 5 for subjecting the mixture in which the diluent solvent is mixed in the waste accumulation facility 3 to methane fermentation,
Waste is weighed by the waste weight weighing means 1,
The waste weight measurement means 1 and the appropriate dilution solvent amount calculation means 2 receive numerical information on the weight of each component measured by the waste weight measurement means 1 and input (introduction) to the appropriate dilution solvent amount calculation means 2 Configured to be
The waste weight weighing means 1 and the waste accumulation facility 3 are configured such that the waste after being measured by the waste weight weighing means 1 is transferred from the waste weight weighing means 1 to the waste accumulation facility 3 and is disposed. 3 is configured to accumulate in
In the appropriate diluted solvent amount calculating means 2, the amount of ammonia nitrogen is calculated based on the numerical information obtained by the waste weight measuring means 1 and the nitrogen content for each component, and the amount of ammonia nitrogen, Based on the weight of all the components weighed, the concentration of ammonia nitrogen in the waste is calculated, and the calculated ammonia nitrogen concentration is compared with the ammonia nitrogen concentration within the allowable range for methane fermentation. The amount of appropriate dilution solvent required to achieve an acceptable ammoniacal nitrogen concentration is calculated,
The appropriate dilution solvent amount calculation means 2 and the dilution solvent input means 4 are arranged so that the dilution solvent is discharged from the dilution solvent input means 4 based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means 2. ,
The diluting solvent input means 4 and the waste storage facility 3 are configured such that the diluted solvent discharged from the diluting solvent input means 4 is introduced into the waste storage facility and mixed with the waste stored in the waste storage facility. And is thereby configured to be adjusted to a total nitrogen concentration that gives an acceptable ammoniacal nitrogen concentration for methane fermentation,
The waste accumulation facility 3 and the methane fermentation tank 5 are configured such that the mixture obtained in the waste accumulation facility 3 is introduced into the methane fermentation tank 5 and used for methane fermentation.

  Examples of the waste weight measuring means 1 include the above-described weighing scale. The waste weight measuring means 1 can be provided, for example, at a waste disposal place or the like in each manufacturing department in a food manufacturing factory.

  In the waste weight measuring means 1, the waste is measured at the time of carrying out, and the measured waste is transferred from the waste weight measuring means 1 to the waste storage facility 3, and the waste storage facility 3 Accumulated at.

  The waste accumulation facility 3 may include foreign matter removing means for removing foreign matters that are not used for methane fermentation from the waste. When such foreign matter removing means is provided, the waste accumulation facility 3 is advantageous in that foreign matter is removed and methane fermentation is performed more efficiently. Examples of the foreign matter removing means include a broken bag sorting device and a compression sorting device. When the waste is composed of garbage and packaging materials such as bags and packs, for example, the liquid obtained by decomposing the garbage and the packaging materials such as bags and packs are separated by the bag-breaking separation device. The packaging material can be removed as a residue.

  In addition, the waste accumulation facility 3 may include a slurrying means for slurrying the accumulated waste. When the slurrying means is provided, the accumulated waste is slurried. At the time of such slurrying, water (for example, industrial water, treated water having a low concentration of nitrogen component discharged from the waste water treatment apparatus, etc.) may be added. When water is added at the time of slurrying, the waste accumulation facility 3 can be configured such that numerical information on the amount of water added is input (introduced) to the appropriate dilution solvent amount calculation means.

  On the other hand, the numerical information of the weight of each component measured by the waste weight measuring unit 1 is input (introduced) to the appropriate diluted solvent amount calculating unit 2.

As the appropriate dilution solvent amount calculation means 2, specifically, for example, a numerical value information input (introduction) unit for inputting (introducing) numerical value information of the weight of each measured component,
Amount of ammonia nitrogen predicted to be generated during methane fermentation based on numerical information on the weight of each component input (introduced) in the weight numerical information input (introduction) section and the nitrogen content of each component Predictive ammonia nitrogen amount calculation unit that calculates the computer,
An ammoniacal nitrogen concentration calculation unit that calculates the concentration of ammoniacal nitrogen in the waste by a computer based on the amount of ammoniacal nitrogen calculated by the predicted ammoniacal nitrogen amount calculation unit and the weight of all measured components; ,
Based on the ammonia nitrogen concentration calculated by the ammonia nitrogen concentration calculation unit and the ammonia nitrogen concentration within the allowable range of methane fermentation, an appropriate dilution solvent amount calculation unit for calculating an appropriate dilution solvent amount for waste by a computer; ,
Examples of the means include an appropriate dilution solvent amount value output unit that outputs a numerical value of the appropriate dilution solvent amount.

For example, the appropriate dilution solvent amount calculation means 2 uses a computer to calculate the appropriate dilution solvent amount,
Numerical information input means for inputting numerical information of the weight of each measured component,
Nitrogen content recording means for recording the nitrogen content for each component;
The recorded nitrogen content value for each component is read out from the nitrogen content recording means, and the nitrogen content for each component is multiplied by the weight value for each component to be converted into ammonia or an ammonium compound during methane fermentation. Ammonia nitrogen amount calculating means for calculating the amount of nitrogen predicted to be the amount of ammonia nitrogen,
Calculate the total weight of the components weighed and multiply the ammonia nitrogen amount calculated by the ammonia nitrogen amount calculation means by the inverse of the numerical value of the weight of all components to obtain the concentration of ammonia nitrogen in the waste. Ammonia nitrogen concentration calculating means for calculating,
An acceptable ammonia nitrogen concentration recording means for recording the ammonia nitrogen concentration within the allowable range of methane fermentation,
Means for comparing the calculated ammonia nitrogen concentration with the recorded allowable ammonia nitrogen concentration to obtain a numerical value of the appropriate amount of diluting solvent necessary to achieve the allowable ammonia nitrogen concentration;
Appropriate dilution solvent amount output means for outputting the value of the appropriate dilution solvent amount,
It may be a computer incorporating an appropriate dilution solvent amount calculation program for causing

  In the appropriate dilution solvent amount calculation means 2, numerical information on the weight of each measured component is input (introduced), and based on the numerical information and the nitrogen content for each component, the component is added to the nitrogen content for each component. By multiplying the numerical value of each weight, the amount of nitrogen that is predicted to be converted to ammonia or an ammonium compound during methane fermentation is calculated by the computer as the amount of ammonia nitrogen, and the amount of ammonia nitrogen calculated Is multiplied by the reciprocal of the weight value of all the components weighed, and the concentration of ammonia nitrogen in the waste is calculated by a computer, etc., and the calculated ammonia nitrogen concentration and the ammonia nitrogen within the allowable range of methane fermentation Compared with the concentration, an appropriate amount of diluting solvent necessary to achieve the ammoniacal nitrogen concentration within the allowable range of methane fermentation is calculated by a computer or the like. Here, in the waste accumulation facility, when the accumulated waste is slurried by the addition of water, an appropriate dilution solvent amount that is an amount obtained by subtracting the addition amount of water is calculated. .

  The numerical value of the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means 2 is transmitted to the dilution solvent input means 4, and at the time of controlling the input amount of the dilution solvent from the dilution solvent input means 4 to the waste accumulation facility 3. It is used as a judgment standard.

  In the waste treatment system shown in FIG. 1, the dilution solvent input means 4 includes a dilution solvent storage tank 4a for storing the dilution solvent, and a dilution solvent input amount adjustment means for supplying a desired amount of the dilution solvent to the waste storage facility. 4b. Therefore, the measured waste accumulated in the waste accumulation facility 3 is supplied with the dilution solvent from the dilution solvent storage tank 4a based on the value of the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means 2. The amount is adjusted by the diluted solvent input amount adjusting means 4 b, whereby the diluted solvent is input to the waste accumulated in the waste accumulation facility 3.

  In the present invention, as another embodiment, there is also an embodiment in which the waste weight weighing unit 1 is charged with an appropriate amount of dilution solvent to the waste according to the result of weighing the waste. .

  As the diluted solvent input amount adjusting means 4b, for example, based on the flow rate of the diluted solvent and the appropriate diluted solvent amount, an automatic valve that distributes the diluted solvent for a period of time until the input of the appropriate diluted solvent amount is completed. Examples thereof include a flow rate control means for controlling the flow rate of the diluting solvent to the storage facility 3. Examples of the flow rate control means include a combination of an integrating flow meter and a sequencer.

  The mixture obtained in the waste accumulation facility 3 is then introduced into the methane fermentation tank 5.

  In the methane fermentation tank 5, microorganisms or microorganism groups that perform methane fermentation or sludge containing the microorganisms are maintained under conditions suitable for methane fermentation. As the microorganism or microorganism group performing the methane fermentation, a conventional microorganism can be used.

  In the methane fermentation tank 5, the mixture is retained for a residence time corresponding to the methane fermentation ability by the microorganisms or the microorganism group or sludge containing the microorganisms, the amount of waste to be treated, and the like.

  After the methane fermentation, methane gas is recovered from the methane fermentation tank 5.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention in detail, this invention is not limited to this Example.

(Experimental example 1)
About the waste containing garbage A, garbage B, and garbage C, the weight ratio of each of garbage A, garbage B, and garbage C was investigated over 4 days. As a result, the weight ratio of the garbage A, the garbage B, and the garbage C on the first day to the fourth day was as shown in Table 1.

  Hereinafter, it is assumed that the water content of waste is 60% by weight, in order to ensure fluidity, 4-fold dilution is performed and the water content is 90% by weight, which is a standard operating condition. At this time, when the ratio of garbage B and garbage C having a high protein content is sufficiently low, the ammoniacal nitrogen concentration is maintained at 2000 mg / L or less which does not cause inhibition of methane fermentation in high temperature (53-55 ° C.) methane fermentation. Is done.

  On the first day and the third day, the predicted ammonia nitrogen concentration is below 2000 mg / L, so the standard operating conditions remain the 4-fold dilution. On the second day, the weight ratio of garbage C increases. Therefore, when the dilution was 4 times, the predicted ammonia nitrogen concentration was calculated to be 2000 mg / L or more. Therefore, as shown in Table 1, additional dilution water was added to make the dilution rate 4.2 times, and the ammonia nitrogen concentration was adjusted to be less than 2000 mg / L. Furthermore, since the weight ratio of garbage B and garbage C also increased on the fourth day, the predicted ammoniacal nitrogen concentration becomes 2000 mg / L or more in the case of 4-fold dilution or 4.2-fold dilution. For this reason, additional dilution water was added, the dilution rate was 4.4 times, and the ammoniacal nitrogen concentration was adjusted to be less than 2000 mg / L.

  On the other hand, it carries out with the standard operating conditions for making the moisture content 90%. In the case of this method, as shown in Table 1, it can be seen that the predicted ammonia concentration exceeds 2000 mg / L.

  The results are shown in Table 1 and FIG.

  In addition, as shown in FIG. 2, in the method of adding dilution water as appropriate and diluting based on the total nitrogen concentration calculated from the weight ratios of garbage A, garbage B, and garbage C, high-temperature methane fermentation It can be seen that the ammoniacal nitrogen concentration in the tank can be maintained below 2000 mg / L. However, it can be seen that the ammonia nitrogen concentration in the methane fermentation tank may exceed 2000 mg / L in the method that is carried out under the standard operating conditions for setting the moisture content of the waste to 90%.

(Experimental example 2)
The waste containing waste A, waste B, and waste C, which is discharged over 10 days, is measured from the weight ratios of waste A, waste B, and waste C. Based on the total nitrogen concentration to be added, dilution water is appropriately added for dilution, and when processing is performed under the standard operating conditions with a moisture content of 90% (4 times dilution), and The ammonia concentration is shown in Table 2 and FIG.

  As shown in Table 2 and FIG. 3, it can be seen that the ammoniacal nitrogen concentration varies depending on the waste components in the waste introduced in 10 days. In addition, based on the total nitrogen concentration calculated from the respective weight ratios of garbage A, garbage B, and garbage C, when diluting by adding water for dilution as appropriate, the day when waste with a high total nitrogen concentration is discharged It can be seen that the ammonia concentration can be easily maintained at 2000 mg or less even if the process continues.

  Note that, for example, when a large amount of high nitrogen-containing waste (protein-containing waste) is discharged due to seasonal fluctuations, the ammonia nitrogen concentration in the methane fermentation tank is relatively high.

  On the other hand, when the ammoniacal nitrogen concentration exceeds 2000 mg / L, methane fermentation is inhibited due to a decrease in the activity of the methane-producing bacteria, propionic acid accumulates in the methane fermentation tank, and the amount of gas generated decreases.

  When adjusting the dilution rate, the ammoniacal nitrogen concentration in the high-temperature methane fermentation tank is always less than 2000 mg / L even when a large amount of high nitrogen-containing waste is discharged, and high-temperature methane fermentation can be performed satisfactorily. .

(Experimental example 3)
When garbage A, garbage B, and garbage C are discharged at a garbage ratio as shown in Table 1, prior to the introduction of waste into the methane fermentation tank, the garbage A, garbage is collected based on the weight at the time of collection. Dilute B and garbage C individually. That is, on the first day, based on the weight at the time of collection, diluted 4-fold with respect to garbage A (ammonia nitrogen concentration: 1500 mg / L) and diluted 4.5-fold with respect to garbage B (ammonia nitrogen concentration) : 2000 mg / L), diluted to 6-fold with respect to garbage C (ammonia nitrogen concentration: 2000 mg / L). Next, the diluted product is mixed and introduced into the methane fermenter. Thereby, the ammoniacal nitrogen concentration in the high-temperature methane fermenter becomes 1724 mg / L, and is suppressed to a level that does not cause inhibition. On the fourth day, on the first day, based on the weight at the time of collection, diluted 4-fold with respect to garbage A (ammonia nitrogen concentration: 1500 mg / L) and 4.5 with respect to garbage B. Dilute twice (ammonia nitrogen concentration: 2000 mg / L) and 6-fold dilution with respect to garbage C (ammonia nitrogen concentration: 2000 mg / L). Next, the diluted product is mixed and introduced into the methane fermenter. Thereby, the ammoniacal nitrogen concentration in the high-temperature methane fermenter becomes 1826 mg / L, and is suppressed to a level that does not cause inhibition.

Example 1
The waste treatment system shown in FIG. 1 was applied to an actual methane fermentation facility. The change of the ammoniacal nitrogen concentration in the liquid in the high temperature methane fermentation tank of the methane fermentation facility is shown in FIG. In FIG. 4, the day when the dilution control is started is defined as day 0, and the elapsed days are indicated on the horizontal axis. In FIG. 4, white circles indicate the estimated ammoniacal nitrogen concentration in the case of standard operating conditions in which 4-fold dilution is performed and the water content is 90% by weight in order to ensure fluidity. Further, in FIG. 4, black square marks indicate measured values of actual ammonia nitrogen concentration. Table 3 shows the amount of dust, the estimated ammonia nitrogen concentration under standard conditions, the fluctuation of the dilution factor during operation, and the measured values of the actual ammonia nitrogen concentration.

  As a result, as shown in FIG. 4, the ammoniacal nitrogen concentration before the application of control was 2000 to 2200 mg / L, indicating signs of methane fermentation inhibition. Thus, after the start of control, after the period required for the liquid in the methane fermentation tank to be replaced (after the 24th day), the ammoniacal nitrogen concentration in the liquid in the methane fermentation tank is maintained at less than 2000 mg / L. It can be seen that the level can be suppressed to a level that does not cause inhibition.

  According to the present invention, efficient methane fermentation becomes possible.

FIG. 1 is a schematic explanatory diagram showing one embodiment of a waste treatment system. FIG. 2 is a diagram showing the concentration of ammoniacal nitrogen in the liquid component after trash fermentation of each day of Table 1 for 10 days at high temperature (53-55 ° C.). In the figure, the triangle marks indicate the results when the standard operating conditions for achieving a moisture content of 90% are performed, and the circle marks indicate the total nitrogen calculated from the weight ratios of garbage A, garbage B, and garbage C. Based on the concentration, the results are shown in the case of diluting by appropriately adding dilution water. Moreover, the broken line part in a figure shows the inhibitory density | concentration of the ammoniacal nitrogen density | concentration in high temperature methane fermentation. FIG. 3 shows the concentration of ammonia nitrogen in the liquid component after methane fermentation of the waste containing waste A, waste B, and waste C discharged over 10 days under the conditions of Experimental Example 2. FIG. In the figure, the diamond marks indicate the results when the standard operating conditions for achieving a moisture content of 90% are used, and the square marks indicate the total nitrogen calculated from the respective weight ratios of garbage A, garbage B, and garbage C. Based on the concentration, the results are shown in the case of diluting by appropriately adding dilution water. Moreover, the thick line part in a figure shows the inhibitory concentration of the ammoniacal nitrogen concentration in high temperature methane fermentation. FIG. 4 is a diagram showing changes in the ammoniacal nitrogen concentration in the fermentation liquor in the high-temperature methane fermentation tank when the waste treatment system shown in FIG. 1 is applied to an actual methane fermentation facility. In the figure, the day when the dilution control is started is defined as day 0, and the elapsed days are shown on the horizontal axis. Also, in the figure, white circles indicate the estimated ammoniacal nitrogen concentration when standard dilution is performed with 4-fold dilution to ensure fluidity and a moisture content of 90% by weight. Further, in the figure, black square marks indicate actual measured values of ammoniacal nitrogen concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waste weight measurement means 2 Appropriate dilution solvent amount calculation means 3 Waste accumulation equipment 4 Dilution solvent input means 4a Dilution solvent storage tank 4b Dilution solvent input amount adjustment means 5 Methane fermentation tank

Claims (3)

  Total nitrogen that measures waste for each component contained in the waste and gives an ammoniacal nitrogen concentration within an acceptable range in methane fermentation based on the weight of each component and the content of nitrogen contained in each component A waste treatment method comprising adding a solvent to the waste so as to have a concentration, adjusting the total nitrogen concentration of the mixture containing the waste, and performing methane fermentation. (A) measuring the weight of the waste for each component;
(B) Based on the weight of each component weighed in step (A) and the content of nitrogen contained in each component, the total nitrogen content of the waste is calculated, and from the total nitrogen content Calculating an appropriate amount of diluting solvent that maintains an acceptable ammoniacal nitrogen concentration for methane fermentation;
(C) The diluted solvent is mixed with the waste weighed in the step (A) so that the appropriate dilution amount calculated in the step (B) is obtained, and the total nitrogen concentration of the obtained mixture is changed to methane. Adjusting the concentration to give an acceptable ammoniacal nitrogen concentration in fermentation, and (D) subjecting the mixture obtained in step (C) to methane fermentation,
The waste disposal method of Claim 1 containing this. Waste weight measuring means for measuring the weight of waste for each component;
Based on the weight of each component weighed by the waste weight weighing means and the nitrogen content of each component, the appropriate amount of solvent for the waste that gives the ammonia nitrogen concentration within the allowable range of methane fermentation is calculated. A dilution solvent amount calculating means;
A waste accumulation facility for accumulating waste after being weighed by the waste weight weighing means;
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, dilution solvent injection means for introducing the dilution solvent into the waste,
A methane fermentation tank for subjecting the mixture mixed with the dilution solvent to methane fermentation,
Based on the appropriate dilution solvent amount calculated by the appropriate dilution solvent amount calculation means, the dilution solvent is mixed with the waste by the dilution solvent input means, so that the waste is ammonia within the allowable range of methane fermentation. A waste treatment system, wherein the mixture is adjusted to a total nitrogen concentration that gives a neutral nitrogen concentration, and the resulting mixture is introduced into the methane fermentation tank and used for methane fermentation.

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