JPH07121398B2 - Bulking controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a bulking control device for an activated sludge treatment process.

B. SUMMARY OF THE INVENTION The present invention is, in a bulking control device for an activated sludge treatment process, using data collecting means for collecting process data of the activated sludge treatment process, and process data collected by the data collecting means, The relationship between sludge capacity index and variable factors including at least one operation factor
GMDH analysis means determined by GMDH (Group Method of Data Handling), and sludge volume index control means for controlling the sludge volume index value of wastewater by changing the operation factor based on the above relationship obtained by this GMDH analysis means. By providing and, the sludge capacity index value of sewage can be accurately and quickly,
Moreover, it is possible to control automatically.

C. Conventional technology Activated sludge treatment method that uses microorganisms to oxidize and decompose organic matter to produce clear and stable treated water is widely used in wastewater treatment. This type of treatment process is, as shown in FIG. 5, a microbial reaction tank in which an aeration tank 1 into which air is sent by a blower 10 and a final settling tank 2 for separating activated sludge containing microorganisms and clear water are provided. The sludge that has been held and settled is returned to the aeration tank 1 using the return sludge pump 4 from the return sludge circuit 3.
And a part of the sludge grown in the process is discharged to the outside of the process by using the excess sludge pump 5.

In such treatment processes, the sedimentation of activated sludge has deteriorated due to various causes, and the bulking phenomenon in which sludge itself disperses and disintegrates often occurs, and water quality is improved by mixing fine SS (suspended matter) into treated water. Was getting worse.
Although the cause of occurrence of this bulking phenomenon has been actively investigated and classified in recent years, the present situation is that no specific countermeasure has been found yet. For example, Orford et al. Reported a BOD of 0.17-3.07 kg / kg mixed suspension concentration.
(Biochemical oxygen demand) -In SS load, the sludge volume index can be evaluated by exponential functions of inflow BOD concentration, mixed suspended matter concentration at aeration tank outlet, DO (dissolved oxygen) concentration, and hydraulic retention time. This shows that when the sludge capacity index fluctuates, a certain effect can be expected by controlling the amount of air blown into the aeration tank, the F / M ratio, the amount of returned sludge, etc. according to the degree. . However, it is not clear which of the various factors that affect the sludge capacity index has the greatest impact.

D. Problems to be solved by the invention Therefore, when the bulking phenomenon occurs in the past, different treatment measures and implementation methods were drafted for each treatment plant based on the experience so far, depending on the occurrence of bulking. Qualitatively, the amount of air blown into the aeration tank, the F / M ratio, and the amount of returned sludge were controlled.

Therefore, it is difficult to perform control accurately and quickly, and manual intervention is required.

The object of the present invention is to solve such problems, to quantitatively control the sludge capacity index value, which is a type of bulking phenomenon, and to suppress its increase accurately and promptly, and also without human intervention. To provide.

E. Means for Solving Problems In order to solve the above problems, the bulking control device of the present invention has a data collecting means for collecting process data of an activated sludge treatment process, and a process data collected by the data collecting means. By using GMDH analysis means for obtaining the relationship between the sludge volume index and the variable factors including at least one operation factor by GMDH, and changing the above operation factor based on the above relationship obtained by this GMDH analysis means, And a sludge volume index control means for controlling the sludge volume index value of the sewage.

F. Action The process data collected by the data collection means is GM
It is input to the DH analysis means, and the relationship between the sludge volume index and the operation factor is analyzed and obtained by GMDH. The sludge capacity index control means changes the operation factor based on the relationship obtained by the GMDH analysis means, and controls the sludge capacity index value of the wastewater.

G. Example Next, an example of the present invention will be described. FIG. 1 shows a block diagram of an activated sludge treatment process using the bulking controller of this embodiment. Sewage treatment system of this process 16
Has an aeration tank 1 which is a microbial reaction tank, and a final settling tank 2. Air is sent to the aeration tank 1 by a blower 10. The wastewater that has flowed into the aeration tank 1 is treated here by a microbial reaction and sent to the final settling tank 2. The wastewater from the aeration tank 1 is separated into activated sludge containing microorganisms and clear water in the final settling tank 2, and the clear water is sent out as treated water. On the other hand, the sludge that has settled is returned to the aeration tank 1 by the return sludge pump 4 through the return sludge circuit 3. At this time, a part of the sludge grown in the process is discharged outside the process by the surplus sludge pump 5. The blower 10, the return sludge pump 4, and the surplus sludge pump 5 are all controlled by a bulking control device described later.

The return sludge circuit 3 is provided with a flow meter 7 for measuring the amount of return sludge and a concentration meter 8 for measuring the concentration of the return sludge as a water quality measuring instrument, and a flow meter 6 for measuring the flow rate of the inflowing wastewater is provided at the inflow part of the wastewater. A flow meter 9 for measuring the amount of excess sludge is provided at the outflow portion of the excess sludge. Further, a flow meter 11 for measuring the flow rate of air is provided in the air supply unit to the blower 10.
These flowmeters and densitometers output their measurement results as process data to the bulking controller 20 described later.

On the other hand, the aeration tank 1 is provided with a DO meter 12, a mixed suspended solids concentration meter 13, a pH meter 14, a sludge volume index meter 15, etc. as water quality measuring instruments, and a bulking control device, which will be described later as water quality data as process data. Sending to 20.

The bulking control device 20 of the present embodiment is a data collection device 21,
GMDH analyzer 22 and sludge capacity index controller, Direct Digital Controller (DDC) 23, is used to input the above process data and aeration tank 1
Blower 1 so that the sludge capacity index value in
0, return sludge pump 4, and excess sludge pump 5 are controlled.

The data collection device 21 is for collecting process data from the flowmeter, water quality measuring instrument, etc., and inputting it to the GMDH analysis device 22, for example, a personal computer or a mini-computer.
Configured by computer. Data collection is performed at a predetermined cycle (for example, every 30 minutes) for a predetermined period (for example, for one year), and the collection result is input to the GMDH analysis device 22 as a database via a Flotpies disk or the like. In addition,
What kind of process data such as DO value, mixed suspended solids concentration, and amount of returned sludge, etc. are collected by the data collection device 21 by artificially selecting what is considered to be closely related to the sludge volume index. Decide

The GMDH analysis device 22 uses the process data input from the data collection device 21 for the quantitative relationship between the sludge volume index value of the wastewater in the aeration tank 1 and the variable factors that affect it.
It is obtained by analysis using GMDH, and is composed of, for example, a mini computer or a large computer.

Here, a brief description will be given of mathematical modeling by GMDH. When the input variables are X ₁ , X ₂ , ..., And the output variables are y, the output variables y are represented by the following equation by the Gabor-Kolmogoroff polynomial.

However, a is a coefficient. (1) Since the equation becomes large number of terms, the combination of a suitable variable (X _i, X _j) for produce the intermediate variable z (X _i, X _j) to _k C ₂ kinds represented by the following formula.

z (X _i , X _j ) ＝ b ₀ + b ₁ x _i + b ₂ x _j + b ₃ x _i ² + b ₄ x _j ² + b ₅ x _i x _j (2) (i, j = 1 , 2, ..., k) The regression coefficient b in the equation (2) is determined by the method of least squares using actual data. By repeating the selection of this intermediate variable,
Consider the intermediate variable with the smallest mean square error as the prediction formula.

Based on such an analysis, the GMDH analysis device 22 determines the following relational expression as a quantitative relation between the sludge capacity index and the process data.

_{SVI = f (Q R, Q} W, DO, ...) (3) where, SVI Sludge volume index value, Q _R is the return sludge quantity (m ₃ /
h), Q _W is excess sludge amount (m ₃ / d), DO is dissolved oxygen concentration (mg /
l). Prior to the analysis, the GMDH analysis device 22 re-edits the process data from the data collection device 21 and selects the necessary factors. At this time, the controllable factors such as the amount of returned sludge, the amount of excess sludge, and the amount of blown air, that is, the operation factors are selected to be included at least one.

Equation (3) is a regression equation showing the relationship between the sludge volume index and the factors that strongly affect this index. Accordance connexion, for example the relationship between the return sludge quantity Q _R and sludge volume index value SVI is (3) the factors other than the return sludge quantity Q _R is fixed to a constant value in the expression, in the operating range of the return sludge quantity Q _R It is obtained by changing. Fig. 2 shows the sludge capacity index value SV thus obtained.
A graph showing the relationship between I and the amount of returned sludge Q _R is shown. Return horizontal axis in this graph sludge quantity Q _R, the vertical axis represents the sludge volume index value SVI. Curve a _1, a _2, a ₃ shows the relationship in the case of each fixed to a different value of the other factors, enough to also increase the return sludge quantity Q _R any curve, the sludge volume index SVI
Indicates a decrease.

From such a relational expression, the GMDH analysis device 22 obtains a relational expression that can be directly used when controlling each operation factor in the DDC 23. (4) is an example of such a relationship, when the sludge volume index value SVI varies, return sludge quantity Q _R
It shows how much should be changed.

^{_{Q R = f (SVI, k}} 1, k 2, ...) ... (4) However, k _1, k _2, ... it is constants. Expressing this equation graphically, so the characteristic curve b ₁ ~b ₃ of Figure 3. Note that each return sludge quantity horizontal axis and the vertical axis of the graph Q _R, represents a sludge volume index value SVI. There are multiple curves because the characteristics differ depending on how the fixed values of factors other than the amount of returned sludge Q _R are set. Here, for example, the sludge volume index value SVI is a rose from 200 ml / g to gradually 320 ml / g, when or using a characteristic curve b _3, the return sludge quantity Q _R is an operation factor of 110m ³ / h by DDC23 It will be controlled to gradually increase to 190 m ³ / h.

By performing the GMDH analysis in this way, it is possible to grasp the quantitative relationship between the sludge volume index value and the operation factor, and in particular by fixing other operation factors, the relationship between a certain operation factor and the sludge volume index value can be obtained. Be clear.

The GMDH analyzer 22 uses the sludge capacity index value SVI as shown in equation (4).
And operation factors and relationship, for example, return sludge quantity Q _R, excess sludge amount Q _W, and determined for each operation factor of the dissolved oxygen concentration DO, outputs online the data to DDC23.

The DDC 23 is composed of a target value setting unit 231, a blown air amount control unit 232, a returned sludge amount control unit 233, and an excess sludge amount control unit 234. When used herein, the return sludge quantity Q _R as an operation factor, target value setting unit 231 and the return sludge amount control unit 233,
Based on the data representing the relationship between the sludge volume index SVI input and return sludge quantity Q _R by operating the return sludge quantity Q _R from GMDH analyzer 22 controls the sludge volume index value. Specifically, return the target value of the return sludge quantity Q _R in accordance with the sludge volume index value input from the sludge volume index apparatus 15 Sludge controller 233
Output to. The returned sludge amount control unit 233 controls the rotation speed of the returned sludge pump 4 according to this target value to operate the returned sludge amount. The target value setting unit 231 outputs a constant value as the target value to the surplus sludge amount control unit 234 and the air blowing control unit 232. Therefore, the rotation speeds of the excess sludge pump 5 and the blower 10 are fixed.

Next, the operation of the bulking control device thus configured will be described with reference to the flow chart shown in FIG. First, the data collecting device 21 collects process data from the flow meters 6, 7, 9, 11 and the water quality measuring instruments 8, 12 to 15 (step 401). The process data to be collected is artificially selected as it is considered to be closely related to the sludge capacity index. In addition, data collection is performed, for example, at intervals of 30 minutes for one year, and the collected data is input to the GMDH analysis device 22 as a data base via a Flotpies disk or the like.

The GMDH analysis device 22 uses the process data input from the data collection device 21 to quantify the sludge volume index value of the wastewater in the aeration tank 1 as shown in equation (3) and the factors affecting it. The physical relationship is obtained by analysis by GMDH as described in detail above (step 402). GMDH analyzer 22
Further, can be used directly to control (4) Sludge volume index SVI and operation factors return sludge amount relational expression between Q _R as formula, excess sludge amount Q _W, and the operation of the dissolved oxygen concentration DO Obtain each factor and output the data online to the DDC 23 (step 403).

Target value setting portion 231 of DDC23, based on the data representing the relationship between the sludge volume index SVI input and return sludge quantity Q _R by operating the return sludge quantity Q _R from GMDH analyzer 22, the sludge capacity Control the index value. Specifically, the sludge capacity index value 15
Outputs the target value of the return sludge quantity Q _R in the return sludge amount control unit 233 in response to the sludge volume index value input from. The returned sludge amount control unit 233 controls the rotation speed of the returned sludge pump 4 according to this target value to operate the returned sludge amount. Target value setting unit 23
1 outputs a constant value to the surplus sludge amount control unit 234 and the blower control unit 232 as the target value during this period. Therefore, the rotation speeds of the excess sludge pump 5 and the blower 10 are fixed (step 404).

Here, the operation of the DDC 23 will be described more specifically using FIG. 3 again. As Figure 3 has already been described, shows the relationship between the return sludge quantity Q _R sludge volume index value SVI to (4) were graphically represented. Further, the data of the relational expression (4) is given from the GMDH analysis device 22 to the target setting unit 231 as described above. For example, if the sludge volume index value SVI gradually increases from 200 ml / g to 320 ml / g, the sludge volume index meter 15 detects this and sends it to the target value setting unit 231. The target value setting unit 231 uses the above relational expression, that is, the target sludge volume target value of 190 m ₃ / h (when the characteristic curve b ₃ is used) when the sludge volume index value SVI is 320 ml / g from the graph of FIG. Is given to the returned sludge amount control unit 233. The return sludge amount control unit 233 receives this target value and controls the return sludge amount to gradually increase from 110 m ₃ / h to 190 m ₃ / h. As a result, the sludge volume index value is controlled to be within the proper range.

In this way, the sludge volume index value in the aeration tank 1 is controlled accurately, quickly, and automatically within the proper range.

By the way, since the sewage treatment system changes due to changes in the inflow load and water quality over time, the above relational expression obtained by the GMDH analyzer 22 needs to be updated according to the change in the treatment system. Therefore, if necessary, process data will be recollected and the relational expression between the sludge capacity index value and the process data will be updated to one that is compatible with the current state of the treatment system (Step 40).
Five).

In this example, the amount of sludge to be returned, the amount of excess sludge, and the amount of air blow were used as operating factors, but in the case of a process in which the amount of returned sludge, the amount of excess sludge, and the amount of air blow have already been controlled,
These control set values can also be used as the operating factors. In this case, the relational expression corresponding to the expression (3) obtained by the GMDH analysis is as follows.

SVI = f (r _set , SRT _set , DO _set …) (5) where r _set is the return rate in the return sludge amount control, SRT _set
Is the set value of the excess sludge amount in SRT control, and DO _set is the DO setting place when the DO constant value control is performed by the air flow rate control. Further, at this time, the relational expression corresponding to the expression (4) is as follows, and when the sludge capacity index value changes in the DDC23,
Change the return rate r _set based on this formula r _set = f (SVI, K ₁ , K ₂ , ...) (6) where K ₁ , K ₂ , ... Are constants.

Further, although the relational expression data is input from the GMDH analysis device 22 to the DDC 23 online, this is not frequently performed, so it can be performed offline.

Further, in the above-mentioned example, the returned sludge amount was used as the operating factor in the DDC23, but by selecting the factor that most affects the sludge volume index value fluctuation by the sensitivity analysis, it becomes effective by using that factor as the operating factor. You can control.

Further, it is also possible to rank the operation factors and sequentially control the operation factors in accordance with the order. That is, a plurality of operating factors are subjected to sensitivity analysis, and the operating factors are ranked according to the degree of influence on the fluctuation of the sludge volume index value. Then, control is performed in order from the highest rank, and when it reaches the upper limit or the lower limit, control is performed by switching to the operation factor of the next rank. Such control is particularly effective when the sludge volume index value cannot be sufficiently controlled with only one operation factor.

In the above-mentioned embodiment, the control target of the DDC 23 is the rotation speed of the pump or the blower, but since the purpose is to control the sludge amount or the blown air amount, it is also possible to achieve the purpose by providing a valve and controlling this. .

H. Effects of the Invention As described above, the bulking control device of the present invention uses the process data of the activated sludge treatment process collected by the data collecting means to determine the relationship between the sludge volume index and the variable factors including the operating factor. It is equipped with a GMDH analysis means that is obtained by GMDH.

Therefore, it is possible to obtain a quantitative relationship between the sludge volume index and the operation factor, and by selecting one operation factor and fixing the other operation factors, the sludge volume index value and the specific operation can be determined. Data can be obtained that represents a clear relationship with the factors. As a result, based on this data, the sludge capacity index control means quantitatively determines how much the target value of the operation factor should be corrected, for example, when the sludge capacity index value has risen, and an accurate Control can be implemented.

Further, the sludge capacity index control means can mechanically obtain the target value based on the above data. Therefore, control can be executed quickly and without human intervention, and it is possible to avoid a situation where the sludge volume index value becomes abnormally high due to the delay in processing in the past.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG.
FIG. 3 is a graph showing an analysis result by the GMDH analyzer of the same embodiment, FIG. 4 is a flow chart for explaining the operation of the same embodiment, and FIG. 5 is a block diagram showing a conventional bulking controller. 20 ... bulking control device, 21 ... data collection device, 22
…… GMDH analyzer, 23 …… DDC, 231 …… Target value setting unit,
232 …… Blower control unit, 233 …… Return sludge control unit, 234
...... Excess sludge amount control unit.

Claims (1)

[Claims] 1. A bulking control device for an activated sludge treatment process, comprising a data collection means for collecting process data of the activated sludge treatment process, and a sludge capacity index using process data collected by the data collection means. Assuming that the input variable is X ₁ , X ₂ ... X _m , the output variable is y, and the coefficient is a, the relationship with the fluctuation factor including at least one operation factor is By changing the operation factor based on the analysis means obtained by the calculation of and the relationship obtained by this analysis means,
A bulking control device comprising: a sludge volume index control means for controlling a sludge volume index value of wastewater.