JP2010155189A - Water treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method and apparatus which estimates the dominance of Bacillus bacteria in real time and can control water to be treated at a dominant state of the Bacillus bacteria in real time on the basis of the estimation. <P>SOLUTION: When the water to be treated is biologically treated via making the Bacillus bacteria dominant, the correlation is obtained in advance between the value of the water quality index of the biologically treated water and the amount of the Bacillus bacteria. Then the value of the water quality index is measured and, from the measured value thereof, the amount of the Bacillus bacteria in the measured water is estimated resting on the correlation. Based on the estimated amount of the Bacillus bacteria, the amount of the sludge to be returned or the amount of the Bacillus bacteria to be supplied is obtained which is required for making the Bacillus bacteria dominant. Additionally, a return sludge pump or a Bacillus bacteria supplying device is controlled according to the obtained amount of the sludge or that of the Bacillus bacteria. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water treatment method and a water treatment apparatus for introducing organic waste water as treated water and biologically treating it with Bacillus bacteria.

  In wastewater treatment facilities, various measures are taken to reduce excess sludge, deodorize, and increase the efficiency of aeration. Odor substances that cause malodor are mainly hydrogen sulfide, methylcaptan, methyl sulfide, methyl disulfide, and ammonia. These odorous substances are generated by decomposing organic substances containing sulfur and nitrogen in an anaerobic state.

  On the other hand, biological treatment techniques utilizing the properties of Bacillus bacteria (hereinafter also referred to as Bacillus bacteria) have been put into practical use. Bacillus bacteria are a kind of soil bacteria present in activated sludge and are considered to have the property of suppressing the action of sulfate-reducing bacteria that produce odorous substances. In order to effectively utilize the characteristics of such Bacillus bacteria, recently, minerals and the like have been supplied to an aeration tank for aerobic treatment of organic wastewater to make Bacillus bacteria dominant, reducing excess sludge, deodorizing, Increasing the efficiency of aeration has been adopted.

  For example, a wastewater treatment apparatus has been proposed in which a biota having Bacillus bacteria as a dominant species is formed in activated sludge and biological treatment is performed using the biota (see, for example, Patent Document 1). Here, a method is proposed in which an oxidizing agent is added to the water to be treated in order to make Bacillus bacteria dominant.

  In addition, in the process of sludge return processing from the sedimentation tank to the aeration tank in the activated sludge treatment, at least a part of the returned sludge is repeatedly exposed to an aerobic state and an anaerobic state by using a Bacillus bacteria-dominating means. Thus, a wastewater treatment facility that predominates Bacillus bacteria has also been proposed (see, for example, Patent Document 2).

  In addition, a wastewater treatment facility that predominates Bacillus bacteria by mixing at least part of the returned sludge as a disinfectant has also been proposed (see, for example, Patent Document 3).

Furthermore, a wastewater treatment facility that predominates Bacillus bacteria by heat-treating at least a part of the returned sludge has also been proposed (see, for example, Patent Document 4).
JP 2005-329301 A JP 2007-319837 A JP 2007-330883 A JP 2008-18357 A

  Thus, when performing an activated sludge process using a Bacillus bacterium, it is necessary to maintain the dominant state of a Bacillus bacterium.

  However, in order to measure the degree of dominance of Bacillus bacteria, it is necessary to perform agar culture from the collected samples. For this reason, it is impossible to measure in real time the water quality and the predominance of the bacterial species that fluctuate in the process of water treatment, and it is therefore difficult to control the treated water to the dominant state of Bacillus bacteria in real time. . In addition, for this measurement, it is necessary to cultivate the sample periodically or to install Bacillus bacteria, which must be newly installed, which increases the equipment cost.

  An object of the present invention is to provide a water treatment method and a water treatment apparatus that can estimate the degree of dominance of Bacillus bacteria in real time and can control the dominance state of Bacillus bacteria in real time based on the result. .

  The water treatment method of the present invention predominates Bacillus bacteria, biologically treats the water to be treated, further precipitates, and returns a part of the precipitated sludge as return sludge to the biological treatment unit by a return sludge pump. In this method, the correlation between the value of the water quality index of the biologically treated water and the amount of the Bacillus bacteria is obtained in advance, the value of the water quality index is measured, and the value of the measured water quality index is Based on the correlation, the amount of Bacillus in the measurement target is estimated, and on the basis of the estimated amount of Bacillus, the amount of returned sludge necessary to predominate the Bacillus is obtained, and the obtained return The return sludge pump is controlled according to the amount of sludge.

  In the water treatment method of the present invention, the correlation between the value of the water quality index of the biologically treated water and the amount of the Bacillus bacteria is obtained in advance, the value of the water quality index is measured, and the measured water quality index Based on the correlation, the amount of Bacillus in the measurement target is estimated based on the correlation, and based on the estimated amount of Bacillus, the amount of supplemental Bacillus necessary to dominate the Bacillus is obtained. You may make it control a Bacillus supply apparatus according to the calculated | required amount of supplemental Bacillus bacteria.

  Further, the water treatment apparatus of the present invention predominates Bacillus bacteria and biologically treats the water to be treated, and further precipitates it, and returns a part of the precipitated sludge as a return sludge to the biological treatment unit by a return sludge pump. A water treatment apparatus for measuring a water quality index value of the return sludge pump for supplying the return sludge to the biological treatment unit to predominate the Bacillus bacteria, and the biologically treated water From the water quality index measuring device, the correlation holding means holding the correlation between the value of the water quality index determined in advance and the amount of the Bacillus bacteria, and the value of the water quality index measured by the water quality index measuring device Based on the correlation, a Bacillus bacterium amount calculating means for estimating the Bacillus bacterium amount to be measured, and on the basis of the estimated Bacillus bacterium amount, the return sludge amount necessary for dominating the Bacillus bacterium is obtained. Sludge amount calculating means transmission, characterized by comprising a return sludge quantity control means for controlling the return sludge pump according return sludge amount this to the obtained.

  Further, the water treatment device of the present invention provides the biological sludge pump with the return sludge pump that supplies the return sludge to predominate the Bacillus bacteria, and the value of the water quality indicator of the biologically treated water. Water quality index measuring device to measure, correlation holding means holding the correlation between the value of the water quality index determined in advance and the amount of Bacillus bacteria, and the value of the water quality index measured by the water quality index measuring device Based on the correlation, the Bacillus bacterium amount calculating means for estimating the Bacillus bacterium amount to be measured, and on the basis of the estimated Bacillus bacterium amount, the supplementary Bacillus bacterium amount necessary for dominating the Bacillus bacterium is calculated. A configuration may be provided that includes a replenishment Bacillus bacterium amount calculating means to be obtained and a replenishment Bacillus bacterium amount control means for controlling the Bacillus supply device in accordance with the obtained replenishment Bacillus amount.

  The water treatment apparatus of the present invention has an autosampler that periodically measures the amount of Bacillus bacteria in the biological treatment unit, and periodically updates the correlation with the water quality index held in the correlation holding means. May be.

  In the water treatment apparatus of the present invention, the water quality index includes odor intensity, suspended solid amount, chemical oxygen demand, dissolved oxygen concentration, total nitrogen value, total phosphorus value, surplus sludge amount, chromaticity, viscosity, Or a combination of one or more of these.

  According to the present invention, the Bacillus bacteria in the water to be treated can always be maintained in a dominant state by online control, so that stable water treatment with less generation of odor and excess sludge can be performed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In one embodiment of the water treatment method according to the present invention, organic wastewater is introduced into an aeration tank as treated water, Bacillus bacteria are dominant in this aeration tank, and biological treatment is performed by an activated sludge method. is there.

  In this method, first, an on-line measurable water treatment index having a correlation with the amount of Bacillus bacteria is specified, and a correlation between them is obtained in advance. For example, since Bacillus bacteria have a deodorizing effect, an odor is specified as a water quality indicator of water to be treated, and this is measured. That is, an odor sensor is provided in an aeration tank (additionally, it may be provided in a return sludge line and an excess sludge line), and an odor is measured on-line. Further, as described above, the correlation between the odor and the amount of Bacillus bacteria is obtained in advance. And from the measured value of this odor, the amount of Bacillus bacteria in the to-be-processed water which measured the odor by the correlation with the amount of Bacillus bacteria is estimated. As a result, for example, when the amount of Bacillus bacteria decreases, the amount of returned sludge is controlled by feedback control, and the returned sludge corresponding to the decrease in Bacillus bacteria is introduced to maintain the dominant state of Bacillus bacteria.

  Thus, by performing the water treatment while maintaining the dominant state of Bacillus bacteria, the generation of odor is small and the amount of excess sludge can be reduced.

  As a water quality indicator, in addition to odor, for example, the weight of excess sludge can be considered. That is, it is known that when the water treatment is performed in a dominant state of Bacillus bacteria, the viscosity of the excess sludge changes. Since the change in the viscosity of the excess sludge means that the weight changes, the amount of Bacillus bacteria can be estimated by obtaining these correlations.

  In this way, the values of the odor sensor, the amount of excess sludge, and other values that can be measured online, such as SS, COD, TN meter, TP meter, aeration tank inflow amount, etc., which are water quality indicators, By measuring offline the degree of dominance of Bacillus bacteria cultured on agar and taking the correlation between them, the degree of dominance of Bacillus bacterium in the measurement target is calculated (estimated) from the online measurement value. A system for determining the supply amount of the corresponding return sludge and predominating Bacillus bacteria is established.

  Since Bacillus bacteria have good sedimentation properties, activated sludge containing a large amount of Bacillus bacteria has good sedimentation properties. When the solid-liquid separation is performed, activated sludge containing a large amount of Bacillus bacteria is efficiently separated from the organic wastewater, and when a part thereof is returned to the aeration tank as return sludge, the proportion of Bacillus bacteria in the aeration tank increases.

  Further, as another embodiment, instead of controlling the amount of returned sludge, the amount of returned sludge is constant, and the amount of Bacillus is reduced, and the necessary amount of Bacillus is directly supplemented to reduce the amount of Bacillus. May be maintained.

  Next, an embodiment of a water treatment apparatus for executing the water treatment method will be described with reference to FIG.

  This water treatment apparatus executes a method of maintaining the dominant state of Bacillus bacteria by controlling the amount of returned sludge.

  In FIG. 1, the organic wastewater first passes through the settling basin 11, is then introduced into the aeration tank 12 as treated water, and after aeration here, sludge is precipitated in the final settling basin 13 and the supernatant water is taken out. It is. A portion of the sludge precipitated in the final sedimentation tank 13 is returned to the aeration tank 12 by a return sludge pump 14 and mixed with the water to be treated. Moreover, the remainder is discharged out of the system by surplus sludge pump 15 as surplus sludge. In addition, flow meters 16 and 17 are provided in the inflow pipe to the aeration tank 12 and the excess sludge discharge pipe from the final sedimentation basin 13, respectively, and the inflow quantity and the excess sludge quantity in the aeration tank flowing through these pipes are measured. . In addition, a water quality index measuring device 18 that measures, for example, odor and SS value, which is a water quality index of the water to be treated, is provided in the downstream portion of the aeration tank 12.

  The controller 19 inputs measurement values from the flow meters 16 and 17 and the water quality index measuring device 18, executes arithmetic processing by a predetermined processing function to be described later, calculates a return sludge amount by the return sludge pump 14, and an aeration tank The to-be-processed water in 12 is controlled to the dominant state of Bacillus bacteria.

  Here, conventionally, monitoring control has not been performed in consideration of Bacillus bacteria. However, it has been known that if Bacillus bacteria exist and the Bacillus bacteria dominate, the amount of excess sludge and odor are reduced and the environment becomes friendly. Therefore, in the present invention, an on-line measurable water quality index generally used in current water treatment facilities, that is, odor, SS value, COD value, DO value, TN value, TP value, surplus From the amount of sludge, the amount of inflow, etc., the amount of returned sludge for dominating Bacillus bacteria is derived. By returning the derived return sludge amount to the aeration tank, Bacillus bacteria can be dominant and excess sludge can be reduced.

  For this purpose, the controller 19 is provided with an input / output unit 20 to input measurement values from the flow meters 16 and 17 and the water quality indicator measuring device 18 and output a control signal to the return sludge pump 14. The controller 19 is configured by a computer or the like, and includes a correlation holding unit 21, a Bacillus bacteria amount calculating unit 22, a returning sludge amount calculating unit 23, and a returning sludge amount control unit 24 as function realizing units.

  The correlation holding means 21 obtains a correlation between the water quality index, for example, the odor value and the amount of Bacillus bacteria in advance, and holds this. That is, the degree of dominance (bacterial amount) of Bacillus bacteria cultured on agar is measured off-line, and the correlation shown in FIG. In the example of FIG. 2, the horizontal axis represents the amount of Bacillus bacteria, and the vertical axis represents odor, which indicates that the odor decreases as the amount of Bacillus bacteria increases. In addition to the value of the odor sensor, the amount of surplus sludge, other values such as SS, COD, TN meter, TP meter, aeration tank inflow, and other values that can be measured online, and agar culture at that time It is also possible to correlate with the degree of dominance of Bacillus bacteria.

なお、水質指標としてＳＳを用いた場合は次式（１ｂ）となる。

他の水質指標を用いた場合も、同様の関係式によりバチルス菌量を求めることができる。返送汚泥量算出手段２３は、算出されたバチルス菌量Ｂに基づき、そのバチルス菌を優占化するために必要な返送汚泥量を次式（２）により求める。

The Bacillus bacteria amount calculation means 22 calculates (estimates) the amount of Bacillus bacteria to be measured based on the correlation value from the value of the water quality index measured by the water quality index measuring device 18, in this case, odor. That is, the following expression (1a) representing the correlation shown in FIG. 2 is set in the Bacillus bacteria amount calculation means 22, and the odor value is input to the input / output unit 20 from the odor sensor which is the water quality indicator measuring device 18. Therefore, the Bacillus bacteria amount B is calculated (estimated) from the correlation shown in FIG.

When SS is used as the water quality index, the following formula (1b) is obtained.

Even when other water quality indicators are used, the amount of Bacillus bacteria can be determined by the same relational expression. Based on the calculated Bacillus bacterium amount B, the return sludge amount calculating means 23 obtains the return sludge amount necessary for predominating the Bacillus bacterium according to the following equation (2).

The return sludge amount is predicted by applying the following equation (3) using the return sludge amount obtained from the relationship between the Bacillus bacteria amount-return sludge amount shown in FIG. Equation (3) is an example using a regression equation.

  About formula (3), coefficient a0, a1, a2, a3 is calculated | required, and the amount of returned sludge is estimated using the odor measured online. As described above, the inflow amount, SS, COD, TN, TP, and excess sludge amount may be substituted for the odor.

  The return sludge amount control means 24 controls the return sludge pump 14 according to the return sludge amount obtained by the return sludge amount calculation means 23.

  Next, the operation of the controller 19 will be described with reference to FIG. Processing is started and a data fetch command is issued (step 401). For this reason, the inflow amount of the to-be-treated water first introduced into the aeration tank 12 from the sedimentation tank 11 is taken into the input / output unit 20 from the flow meter 16 (step 402). Further, the water quality index (in this case, odor) of the water to be treated in the aeration tank 12 is measured by the water quality index measuring device 18 and is also taken into the input / output unit 20 (step 403).

  Based on the taken-in odor value, the amount of Bacillus bacteria in the water to be treated is estimated in the Bacillus bacteria amount calculation means 22 from the correlation (formula 1a) previously held in the correlation holding means 21 (step 404). Furthermore, the amount of sludge to be returned is calculated by the return sludge amount calculation means 23 with respect to the Bacillus bacteria amount estimated in this way, and the return sludge amount control means 24 takes the aeration tank inflow amount into consideration. Then, the return sludge pump 14 is controlled, and the required amount of return sludge is put into the aeration tank 12 (step 405).

  In this way, the Bacillus bacteria is processed in a dominant state, the resulting excess sludge is measured with a flow meter (Step 406), the effect of the Bacillus bacteria dominant is confirmed, and the process is terminated (Step 407). ).

  According to the above embodiment, the odor of water to be treated is measured online, the amount of returned sludge for presuming the amount of bacteria by presuming the amount of bacteria by correlation with Bacillus bacteria based on the measured value Therefore, the Bacillus bacteria in the water to be treated can always be maintained in a dominant state by online control. For this reason, the stable water treatment with few generation | occurrence | production of an odor and the excess sludge amount can be performed.

  Next, the embodiment shown in FIG. 5 will be described. The water treatment apparatus according to this embodiment executes a method for maintaining the dominant state of Bacillus by directly replenishing Bacillus.

Also in this embodiment, the amount of Bacillus in the water to be treated in which the odor is measured is estimated from the measured value of the odor based on the correlation with the amount of Bacillus. In this embodiment, as a result of the estimation, for example, when the number of Bacillus bacteria has decreased, it is possible to directly supply supplemental Bacillus bacteria that correspond to the decrease in Bacillus bacteria by feedback control, that is, by supplementing the deficient Bacillus bacteria. Maintain the dominant state of Bacillus. When using replenishment Bacillus bacteria, the controller 19 inputs measurement values from the flow meters 16 and 17 and the water quality indicator measurement device 18, executes arithmetic processing by a predetermined processing function described later, and replenishes Bacillus by the replenishment Bacillus supply device. The amount of bacteria is calculated, and the water to be treated in the aeration tank 12 is controlled to be in a dominant state of Bacillus bacteria. For this reason, in the water treatment apparatus of this embodiment, the amount of returned sludge to the aeration tank 12 is constant as before (about 10 to 20%). Further, a Bacillus supply device 25 for replenishing Bacillus is provided for the aeration tank. The controller 19 includes a supplemental Bacillus bacteria amount calculation means 26 and a supplementary Bacillus bacteria amount control means 27 as function realizing means. Based on the calculated (estimated) current amount of Bacillus bacteria B, the supplemental Bacillus bacteria amount calculation means 26 obtains the amount of supplementary Bacillus bacteria necessary for predominating the Bacillus bacteria by the following equation (4). .

The following formula (5) is applied using the amount of supplemental Bacillus obtained from the relationship between the amount of Bacillus bacteria and the amount of supplemented Bacillus obtained by the above formula (4) to predict the amount of supplemented Bacillus bacteria. Equation (5) is an example using a regression equation.

  About formula (5), coefficient b0, b1, b2, b3 is calculated | required, and the amount of supplemental Bacillus bacteria is estimated using the odor measured online. As described above, the inflow amount, SS, COD, TN, TP, and excess sludge amount may be substituted for the odor.

  In the above-described embodiment, the correlation holding means 21 measures the degree of dominance (bacterial amount) of Bacillus bacteria cultured on agar off-line, and displays the figure based on the measured value of the odor sensor for this amount of bacteria. Although the correlation as shown by 2 was obtained, it is considered that this correlation changes depending on various conditions. For this reason, it is good to provide the autosampler which measures the amount of Bacillus bacteria of a biological treatment part regularly, to measure the amount of Bacillus bacteria of this sample off-line, and to update a correlation regularly. That is, the sludge is collected regularly, the degree of dominance of Bacillus bacteria is measured, and the online calculation formula is changed. In this way, an accurate correlation can always be maintained, so that highly accurate control is possible.

  As the arithmetic expressions used by each means of the controller 19, the above-described expressions (1), (2), (3), (4), and (5) are used, but other regression analysis may be used.

  Furthermore, in addition to the odor intensity, the water quality index includes, as described above, suspended solid amount, chemical oxygen demand, dissolved oxygen concentration, total nitrogen value, total phosphorus value, surplus sludge amount, chromaticity and viscosity. Any or a combination of one or more of these may be used.

It is a figure explaining one Embodiment of the water treatment apparatus by this invention. It is a figure explaining the correlation with the amount of Bacillus bacteria, and an odor in one Embodiment same as the above. It is a figure explaining the relationship between the Bacillus bacterium amount and return sludge amount in one embodiment same as the above. It is a flowchart explaining the processing operation of the controller in one Embodiment same as the above. It is a figure explaining one Embodiment of the water treatment apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 First sedimentation tank 12 Aeration tank 13 Final sedimentation tank 14 Return sludge pump 15 Excess sludge pump 16 Flow meter 17 Flow meter 18 Water quality index measuring device 19 Controller 20 Input / output part 21 Correlation holding means 22 Bacillus bacteria amount calculation means 23 Return sludge Quantity calculation means 24 Return sludge quantity control means 25 Bacillus bacteria supply device 26 Supplement bacillus bacteria quantity calculation means 27 Supplement bacillus bacteria quantity control means

Claims (6)

It is a water treatment method that predominates Bacillus bacteria and biologically treats the water to be treated, further precipitates it, and returns a part of the precipitated sludge as a return sludge to the biological treatment part by a return sludge pump,
The correlation between the value of the water quality index of the biologically treated water and the amount of the Bacillus bacteria is obtained in advance,
Measure the value of the water quality index, estimate the amount of Bacillus bacteria in the measurement target based on the correlation from the value of the measured water quality index,
Based on this estimated amount of Bacillus, the amount of the returned sludge necessary to dominate the Bacillus is obtained,
Controlling the return sludge pump according to the determined return sludge amount,
A water treatment method characterized by the above. It is a water treatment method that predominates Bacillus bacteria and biologically treats the water to be treated, further precipitates it, and returns a part of the precipitated sludge as a return sludge to the biological treatment part by a return sludge pump,
The correlation between the value of the water quality index of the biologically treated water and the amount of the Bacillus bacteria is obtained in advance,
Measure the value of the water quality index, estimate the amount of Bacillus bacteria in the measurement target based on the correlation from the value of the measured water quality index,
Based on this estimated amount of Bacillus, the amount of supplemental Bacillus required to dominate the Bacillus is obtained,
Control the Bacillus feeder according to the determined amount of supplemented Bacillus,
A water treatment method characterized by the above. It is a water treatment device that predominates Bacillus bacteria and biologically treats the treated water, and further precipitates it, and returns a part of the precipitated sludge as a return sludge to the biological treatment unit by a return sludge pump,
The return sludge pump that supplies the return sludge to dominate the Bacillus bacteria for the biological treatment unit,
A water quality indicator measuring device for measuring the value of the water quality indicator of the biologically treated water;
Correlation holding means for holding a correlation between the value of the water quality index determined in advance and the amount of the Bacillus bacteria;
Bacillus bacteria amount calculating means for estimating the amount of Bacillus bacteria to be measured based on the correlation from the value of the water quality index measured by the water quality index measuring device,
Based on the estimated amount of Bacillus bacteria, a return sludge amount calculating means for obtaining the amount of returned sludge necessary for predominating the Bacillus bacteria,
Return sludge amount control means for controlling the return sludge pump according to the obtained return sludge amount;
A water treatment apparatus comprising: It is a water treatment device that predominates Bacillus bacteria and biologically treats the treated water, and further precipitates it, and returns a part of the precipitated sludge as a return sludge to the biological treatment unit by a return sludge pump,
The return sludge pump that supplies the return sludge to dominate the Bacillus bacteria for the biological treatment unit,
A water quality indicator measuring device for measuring the value of the water quality indicator of the biologically treated water;
Correlation holding means for holding a correlation between the value of the water quality index determined in advance and the amount of the Bacillus bacteria;
Bacillus bacteria amount calculating means for estimating the amount of Bacillus bacteria to be measured based on the correlation from the value of the water quality index measured by the water quality index measuring device,
Based on this estimated amount of Bacillus, a supplemental Bacillus amount calculating means for determining the amount of supplemental Bacillus necessary to dominate the Bacillus,
Replenishment Bacillus bacteria amount control means for controlling the Bacillus supply device according to the obtained replenishment Bacillus amount,
A water treatment apparatus comprising:   An autosampler that periodically measures the amount of Bacillus bacteria in the biological treatment unit, and the correlation with the water quality index held in the correlation holding means is periodically updated. Item 5. A water treatment apparatus according to item 4.   The water quality index is any one of one or more of odor intensity, suspended solid amount, chemical oxygen demand, dissolved oxygen concentration, total nitrogen value, total phosphorus value, surplus sludge amount, chromaticity, viscosity. The water treatment device according to any one of claims 3 to 5, wherein the water treatment device is a combination.

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