JP2002113459A - Method for controlling pumping of polluted ground water and system for cleaning polluted ground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean ground water efficiently by correcting the amount of ground water to be pumped up by a pump properly corresponding to the variation of the concentration of contaminants in the ground water which changes in association with pumping and the risk of a ground environment. SOLUTION: A submergible motor pump 3 for pumping up polluted ground water is installed in a pumping well 1, and a flow meter 5 and a concentration sensor 6 are fitted to a pumping pipe 4 extended from the discharge port of the pump 3 to the ground. A water level sensor 7 is installed in a ground water monitoring well 2. A fuzzy controller operates the optimum amount of pumping in consideration of the contribution to ground water cleaning and risk to the ground environment from the change of ground water level ΔH obtained from the amount of pumping Q(t) per unit time measured by the flow meter 5, the change of a pollutant concentration d(t) obtained from a measured value by the concentration sensor 6, and the measured value of a ground water level GWL by the water level sensor 7 with the use of a membership function and a fuzzy inference rule by fuzzy inference and controls a driving device 9 for driving the pump 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for properly controlling a pumping amount in a well for purifying contaminated groundwater.

[0002]

2. Description of the Related Art In recent years, contamination of groundwater by contaminants such as wastes from households and factories and agricultural chemicals has become a problem. As a method of purifying such contaminated groundwater, conventionally, a required number of wells have been excavated in the ground of the contaminated area, and the contaminated groundwater in the contaminated ground area has been pumped up and purified. There is known a method of purifying a contaminated ground region by condensing water into a contaminated ground region and allowing the contaminated ground region to permeate.

[0003]

In such a pumped well of contaminated groundwater, a submersible pump is operated based on a planned pumping amount set in advance by investigating the distribution of contaminated groundwater. However, in such a method,
It is not possible to cope with changes in the concentration of contaminants in groundwater that change with pumping, which often results in errors from the time of the preliminary survey. In addition, depending on the amount of pumped water, there is a risk that the wells nearby will die or the land will sink, which makes it difficult to purify the water as planned.

[0004] The present invention has been made in view of the above-mentioned problems, and its technical subjects are to respond to changes in the concentration of groundwater contaminants that change with pumping and risks to the ground environment. Another object of the present invention is to efficiently correct the amount of water pumped by a pump and efficiently purify groundwater.

[0005]

SUMMARY OF THE INVENTION In order to effectively solve the above-mentioned technical problems, a method of controlling the pumping of contaminated groundwater according to the present invention is directed to a method of controlling the degree of contribution to groundwater purification by pumping contaminated groundwater from a pumping well. Evaluate by fuzzy inference which inputs the amount of change in pollution concentration and the amount of pumped water per unit time, and evaluate the risk to the ground environment by the pumping by fuzzy inference which inputs the amount of groundwater level change or the amount of land subsidence, The optimum pumping amount is determined by fuzzy inference using the evaluation data of the degree of contribution to groundwater purification and the evaluation data of the risk to the ground environment, and the pumping is controlled based on the optimum pumping amount.

[0006] The "risk of the ground environment" mentioned here includes, for example, land subsidence due to a drop in groundwater level, withering of a nearby well, and the like.

In the method for controlling the pumping of contaminated groundwater according to the present invention, the degree of contribution e (t) to groundwater purification is such that the amount of change in the concentration of pollutants in groundwater is d (t) and the amount of pumping is Q (t). The following equation e (t) = {d (t−1) −d (t)} / Q (t) (1)

[0008] In the above-mentioned method of controlling the pumping of contaminated groundwater according to the present invention, the determination of the optimum pumping amount is based on a membership function represented by a plane figure as evaluation data of the degree of contribution to groundwater purification, and a risk to the ground environment. This is performed by superimposing a membership function represented by a plane figure as evaluation data and obtaining the center of gravity.

In the method of controlling the pumping of contaminated groundwater according to the present invention, the end of the purification or the occurrence of an abnormality in the system is determined from the degree of contribution e (t) to the purification of the groundwater obtained by the above equation (1). .

[0010] In order to realize the method for controlling the pumping of contaminated groundwater according to the present invention, a contaminated groundwater purification system according to the present invention includes a pump installed in a pumping well and pumping groundwater;
Flow rate measuring means for measuring the amount of groundwater pumped by the pump per unit time; concentration measuring means for measuring the concentration of contaminated groundwater pumped from a pumping well; and a groundwater level installed in the groundwater level monitoring well. And a fuzzy controller for controlling the driving of the pump, wherein the fuzzy controller determines the degree of contribution to groundwater purification by pumping contaminated groundwater from a pumping well from the measured value by the concentration measuring unit. Estimated by fuzzy inference with the input amount of change in groundwater contamination concentration obtained and the amount of pumped water per unit time measured by the flow rate measuring means, the risk to the ground environment due to pumping is measured by the water level measuring means. Is evaluated by fuzzy inference using the groundwater level change amount or the land subsidence amount obtained from And it outputs the control data based on the optimal pumping amount obtained by the fuzzy inference to input evaluation data of risk to every evaluation data and soil environment.

[0011]

FIG. 1 is an explanatory view showing a preferred embodiment of a contaminated groundwater purification system according to the present invention. In the drawing, reference symbol G denotes the ground in the contaminated area, and GWL denotes the groundwater level in the ground G. is there. A pumping well 1 and a groundwater level monitoring well 2 are drilled in the ground G by boring or the like.

The pumping well 1 is provided with a submersible pump 3 for pumping groundwater at a position sufficiently deeper than the groundwater level GWL, and a pump 4 extending from the discharge port to the ground has a flow meter. 5 and a density sensor 6 are provided. The flow meter 5 measures the amount of groundwater pumped from the pumping well 1 by the submersible pump 3 per unit time, and the concentration sensor 6 measures the contaminated concentration of the pumped groundwater. On the other hand, the groundwater level monitoring well 2 is
A water level sensor 7 for measuring a groundwater level GWL is provided in a place where it is considered that the effects of well withering and ground subsidence due to pumping water from the ground are high.

The measurement data of the flow meter 5, the concentration sensor 6, and the water level sensor 7 are input to a fuzzy controller 8.
The fuzzy controller 8 includes a data memory 81 for temporarily storing each measurement data, a fuzzy inference memory 82 for storing each membership function and fuzzy inference rules to be described later, and a membership function from each measurement data. And an operation unit 83 for executing a fuzzy inference operation based on a fuzzy inference rule.

More specifically, the fuzzy controller 8 firstly serves as an antecedent part of the fuzzy inference, with the pumping rate Q (t) per unit time measured by the flow meter 5 and the groundwater calculated from the value measured by the concentration sensor 6. Contamination concentration change d (t)
And the groundwater level change amount or the land subsidence amount ΔH obtained from the measured value of the groundwater level GWL by the water level sensor 7 are applied to a membership function represented by a predetermined plane figure for each, and The fuzzy inference operation is performed using the obtained fuzzy inference rules, whereby the membership function data of each plane figure obtained as a consequent part of the fuzzy inference is synthesized, and the center of gravity position is obtained to purify groundwater. The driving device 9 that drives the motor of the submersible pump 3 is controlled so that the optimum pumping amount is obtained in consideration of the contribution to the above and the risk to the ground environment such as the land subsidence and the death of the nearby well.

The evaluation of the degree of contribution e (t) to groundwater purification is based on the pumping rate Q (t) per unit time and the change in groundwater contamination concentration d (t). {d (t−1) −d (t)} / Q (t) (1)

That is, the contaminated groundwater purification system according to this embodiment has a pumping amount Q such that the contribution e (t) obtained by the above equation (1) converges toward the target value.
(t) is controlled. Therefore, when e (t) reaches the target value, it is determined that the purification is completed at that point, and the pumping by the submersible pump 3 is stopped, and the e (t) does not converge toward the target value and becomes large. If there is a deviation, it can be determined that a system abnormality has occurred.

Calculation of Pumped Amount Based on Contribution to Groundwater Purification In calculation of pumped water based on contribution to groundwater purification,
First, two input data of a pumping amount Q (t) per unit time measured by the flow meter 5 and a pollutant concentration change amount d (t) obtained from the measurement value of the concentration sensor 6 are respectively fuzzy. This applies to the membership function in the antecedent part of inference. Figure 2 shows the membership function for pumped water.
As shown in Fig. 3, the horizontal axis shows the pumping amount and the vertical axis shows the degree of conformity.
As shown in FIG. 7, the horizontal axis indicates the amount of change in the concentration of contamination, and the vertical axis indicates the degree of conformity.

For example, the pumping amount per unit time is Q (t) a,
When the amount of change in the pollution concentration of groundwater is d (t) a, when these data are applied to the corresponding membership functions, the pumped water yield is shown in FIG. As shown in FIG. 3, the amount of change in the contamination concentration is “slightly large” and the degree of conformity is 0.8. Then, in the antecedent part of the fuzzy inference, since the smaller one of a plurality of fitness levels serving as AND conditions is adopted, the fitness level of contribution to groundwater purification is 0.7.

Next, the data of the amount of pumped water and the amount of change in the concentration of contamination are adapted to fuzzy inference rule 1 as shown in Table 1 below. In the above example, the pumping amount is "target range"
Since the amount of change in the concentration of contamination is "slightly large", if this is adapted to the fuzzy inference rule 1, the amount of change in the pumped water is "slightly large".

[Table 1]

Next, the data of the degree of conformity and the amount of change in pumped water obtained as described above are adapted to the consequent part in the fuzzy inference. In the above example, since the pumping variation is “slightly large” and the degree of conformity of the contribution to groundwater purification is 0.7, the optimum pumping amount based on the evaluation of the degree of contribution to groundwater purification is determined.
Q _A is the membership function of the fuzzy inference after matter portion shown in FIG. 4, the horizontal axis of the center of gravity G _A of figure A trapezoidal shape shown in fitness 0.7 following solid thick frame in "slightly higher" Obtained as coordinates.

Calculation of Pumping Amount Due to Risk of Ground Environment On the other hand, in calculation of pumping amount due to risk of ground environment, the ground obtained from the measured value of groundwater level GWL by the water level sensor 7 installed in the groundwater level monitoring well 2 The value of the amount of settlement (or the amount of change in groundwater level) ΔH is applied to the membership function of the antecedent part in fuzzy inference. The membership function of the land subsidence amount is, as shown in FIG.
The horizontal axis indicates the amount of land subsidence, and the vertical axis indicates the degree of conformity.

For example, when the amount of land subsidence is ΔHa, when this data is applied to the membership function shown in FIG. 5, the amount of land subsidence is “slightly small” and the conformity is 0.6. As described with reference to FIG. 2, the yield Q (t) a is 0.7 in the “target range”, and the antecedent in the fuzzy inference has a plurality of fitness levels that are AND conditions. Since the smaller one is adopted, the degree of conformity to the risk of the ground environment is 0.6.

Next, the data of the pumping amount and the land subsidence amount are adapted to fuzzy inference rule 2 as shown in Table 2 below. In the above example, the pumping amount is the “target range” and the land subsidence amount is “slightly small”. Therefore, if this is adapted to the fuzzy inference rule 2, the pumping amount is “slightly small”.

[Table 2]

Next, the data of the degree of conformity and the amount of change in pumped water obtained as described above are adapted to the consequent part in the fuzzy inference. In the above example, since the pumping variation is “slightly small” and the conformity to the risk of the ground environment is 0.6, the optimum pumping amount Q to be controlled from the risk of the ground environment is Q
_B is the membership function of the fuzzy inference after matter portion shown in FIG. 6, the horizontal axis coordinate of the center of gravity G _B of figure B trapezoidal shape shown in fitness 0.6 following solid thick frame in "slightly less" Is required.

Calculation of Optimum Pumping Amount Next, the graphic A shown in FIG. 4 and the graphic B shown in FIG. 6 are superimposed as shown in FIG.
The center of gravity G is obtained, and the coordinate value of the horizontal axis of the center of gravity G is output as the final optimum pumping amount Q.

That is, in the above-described method, the amount of pumped water Q (t) per unit time constantly monitored on site,
Based on the change in groundwater contamination concentration d (t) and the change in groundwater level ΔH, the planned pumped water output is adjusted so that the concentration of contaminated groundwater changes with pumping and the optimal pumped water output according to the change in groundwater level. Since the driving of the submersible pump 3 is feedback-controlled by this, the pumping can be performed with the optimum pumping amount having little influence on the ground environment, the efficiency of groundwater purification can be improved, and the period required for purification can be improved. Shortening can be achieved. In addition, as described above, when e (t) reaches the target value, it is determined that purification is completed at that time, pumping is stopped, and when e (t) greatly deviates from the target value, It can be determined that a system abnormality has occurred.

The contaminated groundwater pumped up by the pump 3 is purified by a water purification device (not shown) and then discharged to nearby rivers or waterways or sprinkled on the ground. It is possible to promote the purification by condensing and infiltrating into the contaminated ground.

[Example] FIG. 8 shows the ground in which groundwater is contaminated with trichlorethylene having a concentration approximately twice that of the environmental standard (approximately 0.06 mg / L). Fig. 3 shows changes in the concentration of groundwater contamination when the contaminated groundwater is pumped by the method of the present invention. As is apparent from this figure, according to the present invention, the number of days required for purification until the contamination concentration becomes 0.02 mg / L or less is reduced by about 40% compared to the conventional technology, It was confirmed that the efficiency was improved by about 40%.

[0029]

According to the present invention, groundwater generated by pumping from contaminated groundwater pumping wells by fuzzy inference from measured data of the amount of change in the contaminated concentration of groundwater, the amount of pumped water per unit time, and the amount of groundwater level change. The planned pumped water output is corrected so as to obtain the optimum pumped water output in consideration of the contribution to purification and the risk to the ground environment due to the change in the groundwater level due to the pumped water, and the pump is controlled based on this. , And pumping can be performed with an optimum pumping amount that has little effect on the ground environment. As a result, purification efficiency can be improved and the period required for purification can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing a preferred embodiment according to the present invention.

FIG. 2 is an explanatory diagram showing a membership function of a pumping amount of a fuzzy inference antecedent based on a degree of contribution to groundwater purification applied in the present invention.

FIG. 3 is an explanatory diagram showing a membership function of a pollutant concentration change amount of a fuzzy inference antecedent according to a degree of contribution to groundwater purification applied in the present invention.

FIG. 4 is an explanatory diagram showing a membership function of a consequent part of fuzzy inference based on a degree of contribution to groundwater purification applied in the present invention.

FIG. 5 is an explanatory diagram showing a membership function of a land subsidence amount of a fuzzy inference antecedent due to a risk to a ground environment applied in the present invention.

FIG. 6 is an explanatory diagram showing a membership function of a consequent part of fuzzy inference based on risk to the ground environment applied in the present invention.

FIG. 7 is an explanatory diagram showing the determination of the optimum pumping amount by the centroid method of the membership function of the consequent part applied in the present invention.

FIG. 8 is an explanatory diagram showing measurement results of groundwater contamination concentration when contaminated groundwater is pumped by a conventional technique and when contaminated groundwater is pumped by the method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 pumping well 2 groundwater level monitoring well 3 submersible pump 5 flow meter 6 concentration sensor 7 water level sensor 8 fuzzy controller

Claims (5)

[Claims] The degree of contribution to groundwater purification by pumping contaminated groundwater from a pumping well is evaluated by fuzzy inference using the amount of change in groundwater contaminant concentration and the amount of pumped water per unit time as inputs. The risk to water is evaluated by fuzzy inference using the groundwater level change or ground subsidence as input, and optimal pumping is performed by fuzzy inference using the evaluation data of the degree of contribution to groundwater purification and the evaluation data of risk to the ground environment as input. A method for controlling the pumping of contaminated groundwater, comprising determining a pumping amount and controlling pumping based on the optimum pumping amount. 2. The degree of contribution to groundwater purification e (t) is expressed as follows: d (t) is the amount of change in the concentration of contaminated groundwater, and Q is the amount of pumped water per unit time.
The polluted groundwater according to claim 1, wherein (t) is evaluated by the following equation: e (t) = {d (t-1) -d (t)} / Q (t) (1) Pumping control method. 3. The determination of the optimum pumping amount is performed by a membership function represented by a plane figure as evaluation data of the degree of contribution to groundwater purification and a membership function represented by a plane figure as evaluation data of risk to the ground environment. 2. The method according to claim 1, wherein the control is performed by superimposing functions and determining the center of gravity. 4. The contaminated groundwater according to claim 2, wherein the end of the purification or the occurrence of an abnormality in the system is determined from the degree of contribution e (t) to the purification of the groundwater obtained by the equation (1). Pumping control method. 5. A pump installed in a pumping well for pumping groundwater, a flow rate measuring means for measuring an amount of groundwater pumped by the pump per unit time, and a pollutant concentration of groundwater pumped from the pumping well. A concentration measuring means for measuring, a water level measuring means installed in the groundwater level monitoring well to measure the groundwater level, and a fuzzy controller for controlling the driving of the pump, wherein the fuzzy controller is provided with a contaminated groundwater from a pumping well. The degree of contribution to groundwater purification by pumping is evaluated by fuzzy inference using as input the amount of change in the contaminant concentration of groundwater obtained from the measured value of the concentration measuring means and the amount of pumped water per unit time measured by the flow rate measuring means. And the risk to the ground environment due to pumping is the groundwater level change or land subsidence determined from the measured values by the water level measuring means. Evaluation is performed by fuzzy inference with input as input, and control data is output based on the optimal pumping amount obtained by fuzzy inference with input of the evaluation data of the degree of contribution to groundwater purification and the evaluation data of risk to the ground environment as input. A polluted groundwater purification system.