JP4180563B2 - Precipitation separation operation measurement management method and apparatus - Google Patents

Description

The present invention relates to a water treatment system that precipitates and separates turbidity or suspended solids (hereinafter referred to as SS) in raw water, such as adding flocculant or the like to the raw water to floculate turbidity or SS, aeration, etc. Process, guide the solid-liquid mixture to the precipitation tank, measure and manage whether or not the operation of precipitating and separating solids is done properly, make the drug injection amount such as flocculant appropriate, The present invention relates to a measurement management method and apparatus that contributes to stabilization of treated water by detecting abnormalities in the precipitation separation process at an early stage.

Conventionally, turbidity or wastewater containing SS is treated by adding acid, alkali, flocculant, etc. to the wastewater to flock the turbidity or SS in the wastewater, leading to a sedimentation tank, and precipitating solid matter. Coagulation sedimentation treatment that separates, activated sludge treatment that decomposes turbidity or SS by microbial activity by aeration in an aeration tank, or adheres and adsorbs to activated sludge, then leads to the precipitation tank and precipitates and separates with activated sludge It is done by. When only the turbidity in the wastewater needs to be removed, a coagulation sedimentation process that is easy to operate and can be processed in a short time has become widespread.

In waste water coagulation treatment, inorganic coagulants and polymer coagulants such as aluminum chloride, polyaluminum chloride, aluminum sulfate, ferric chloride, and polyferric sulfate are used to flock the turbidity of raw water, It is introduced into a precipitation tank and separated into solid and liquid by specific gravity difference. The quality of agglomeration depends on various factors such as the quality and amount of the aggregating agent, the concentration and nature of the turbidity of the raw water, and the characteristics of the agglomeration reaction precipitation apparatus. Even after specifying the apparatus and the flocculant, the quality of the flocculation varies greatly if the properties of the raw water vary. For this reason, in order to properly manage the operation of the coagulation sedimentation treatment, various measurement monitoring instruments are used, and it is necessary to adjust the addition amount of the coagulant based on the measured values. Measuring instruments used in coagulation sedimentation treatment include raw water flow meter, raw water turbidity meter and other water quality measuring devices such as pH and conductivity, flocculant added flow meter, turbidity meter for supernatant water in sedimentation tank There are the interface meter of sedimentation sludge in the sedimentation tank, the extraction sludge of sedimentation sludge and the SS concentration meter of flocculated mixture. Even in the activated sludge treatment, there are problems such as poor precipitation due to filamentous fungi, and operation management of the solid-liquid separation operation in the sedimentation tank is important, and the same instrument is used.

The data measured using these instruments is used to manage the operation status of the precipitation operation, and in order to achieve an appropriate operating state, the coagulation sedimentation treatment is suitable for activated sludge treatment, such as the amount of coagulant added and the amount treated. The amount of treated water, the amount of returned sludge, aeration conditions, etc. are adjusted. However, it is not easy to change the conditions appropriately if the fluctuations in raw water and treatment conditions are large. The reason for this is that with current measuring instruments, for example, several hours for coagulation sedimentation treatment, more than half a day for only the sedimentation tank for activated sludge treatment, until the fluctuation of the raw water appears in the change in turbidity of the sedimentation supernatant water. This is because there is a response delay of more than one day from the fluctuation. The difficulty is expressed in various proposals in the automatic control method of the amount of flocculant added, even in the case of the coagulation sedimentation treatment which is simpler than the activated sludge treatment and can be carried out in a short time. As a typical control method, turbidity of sedimentation tank treated water is measured, and feedback control that controls the amount of flocculant added measures the turbidity of the actual sedimentation tank treated water, and the response delay in the device is measured by a computer. A method of correcting and controlling the addition amount of the flocculant is disclosed (for example, see Patent Document 1). In addition, feedforward control that measures the flow rate, turbidity, and other characteristic values of raw water, and controls the amount of flocculant added using a relational expression that calculates the relationship between the estimated turbidity load and the amount of flocculant injected Has also been proposed (see, for example, Patent Document 2).

However, in the feedback control, there is a response delay of several hours for the fluctuation of the raw water to clearly affect the treated water from the settling tank, and there is a problem that cannot be corrected when the fluctuation of the raw water is large. In feed-forward control, ambiguity due to response delay can be avoided, but the factors affecting aggregation are not only the turbidity of raw water, but also factors such as pH and salt concentration, and the behavior of colloids cannot be easily clarified. There are factors, and in addition to the high cost of measuring instruments, there is a problem that it is difficult to accurately grasp the aggregation behavior depending on the quality of raw water.

As described above, the current technology is insufficient to accurately grasp the behavior of precipitation by any method. In order to accurately capture the behavior of agglomeration and reflect it in driving operations, reduce the ambiguity due to response delays that make feedback control difficult, and accurately grasp the agglutination factors in feedforward control. There is a need for a more appropriate measurement management instrument that avoids difficulties. In activated sludge treatment, the response is large, as represented by countermeasures against sedimentation defects caused by filamentous fungi, so it is more difficult to elucidate the phenomenon and take countermeasures. If this can be done properly, it will lead to the elucidation and countermeasures of the phenomenon. For this reason, an apparatus capable of appropriately measuring and managing the precipitation operation is required.
JP 2004-8901 A JP 2002-66209 A

  The present invention uses a new measuring device to measure and manage the operating state in the sedimentation operation. In the coagulation sedimentation process, the best treatment water turbidity, the maximum sludge compaction state, the minimum sludge volume, and the smallest coagulant. An object of the present invention is to provide a measurement management device that can be realized with an added amount, and that can be used in activated sludge treatment, which is associated with measures for elucidating sedimentation defects in a sedimentation tank and enables stable treatment.

The gist of the present invention is as follows. That is, the precipitation separation operation measurement management method according to the present invention,
In a water treatment system that settles and separates turbidity or suspended solids by leaving waste water containing suspended or suspended solids (hereinafter referred to as raw water), the solid-liquid mixture before entering the sedimentation tank A first step of charging a set amount to the settling container, a second step of discharging the liquid while maintaining the relative position between the liquid level and the sludge interface level of the settling container after leaving for a set time, and discharging The third step to measure the discharge elapsed time and the suspended solids or turbidity of the discharged liquid during the operation, and at least the time that the precipitated sludge interface passes from the measured value is detected, the discharge speed of the discharged liquid and the precipitated sludge Including a fourth step of calculating the sludge volume of the precipitated sludge from the time that the interface passes, and a fifth step of measuring the turbidity of the supernatant liquid phase from the measured value after passing through the precipitated sludge interface. (Claim 1).

  In this case, before the raw water enters the settling tank, in the case of performing a treatment such as adding flocculant or the like to flocculate turbid or suspended solids or aeration, it is allowed to stand in addition to the first step. The method includes a step of charging raw water into a precipitation vessel and a step of measuring suspended solids or turbidity of the raw water (claim 2).

  Moreover, in addition to said 1st process, the process of charging the supernatant water of a sedimentation tank to a stationary sedimentation container, and the process of measuring the suspended solid or turbidity of this supernatant water are characterized by the above ( Claim 3).

Further, in the third step, the method further includes a step of judging whether or not the sedimentation sludge phase is compacted from the magnitude of variation in the measured value of suspended solids or turbidity when the sedimentation sludge phase is passing through. (Claim 4).
In addition, in the third step, liquid discharge is completed from the change in the measured amount when the cell that measures suspended solids or turbidity is full and the measured amount when the cell runs out of liquid. The method further includes a step of measuring the liquid discharge rate and measuring the liquid discharge speed.

The precipitation separation operation measurement management device according to the present invention is a precipitation separation operation measurement management used in a water treatment system for precipitating and separating turbid or suspended solids by allowing raw water to stand, wherein the solid separation before entering the precipitation tank. Means for charging a set amount of the liquid mixture into the stationary sedimentation container; means for discharging the liquid while maintaining the relative position between the liquid level of the stationary sedimentation container and the sludge interface level after standing for a set time; and Means to measure the discharge elapsed time and the suspended solids or turbidity of the discharged liquid, and at least the time that the precipitated sludge interface passes from the measured value, and the discharged liquid discharge speed and the precipitated sludge interface pass Means for calculating the sludge volume of the precipitated sludge from the time, and means for measuring the turbidity of the supernatant liquid phase from the measured value after the precipitation sludge interface has passed (Claim 6). ).
According to each of the above inventions, the precipitation separation operation can be appropriately managed, and the discharge rate used in the apparatus can be automatically calibrated and verified, thereby improving the reliability of the apparatus.

Such water treatment system precipitation separation operation measurement and management devices include activated sludge treatment, solid precipitation such as coagulation sedimentation treatment, coagulation flotation treatment and sludge dewatering device that add acid, alkali agent and flocculant to promote solid-liquid separation. Targeting liquid separators and other water treatment devices, it is possible to achieve proper operation management and to stabilize the quality of treated water.
The feature of the present invention is that the turbidity of the supernatant liquid, the interface position and the discharge time can be used to measure the sludge volume and the compacted sludge, and the turbidity of raw water and treated water can also be measured with a single device. In addition, it is possible to appropriately control the amount of the flocculant added based on the measured values. Each measured value can be measured by using a dedicated measuring instrument, but it is complicated and expensive to measure the above measured value with a combination of existing instruments. It is not enough. For example, as a device for detecting the sludge interface, there is a method of detecting by reflection of light, but measurement becomes impossible when a part of the coagulated sludge is floating. In addition, there is a method of measuring the turbidity of the treated water and the sludge interface while moving the turbidity sensor in the sedimentation tank, but this method has the disadvantage that the apparatus is complicated such as the structure of sensor movement. Also, this method cannot measure the compactness.
Another feature is that in the present invention, the solid-liquid mixed solution before entering the settling tank is sampled, the measurement device has a short simulated settling tank, and the measurement and management is performed with the turbidity of the supernatant. The result can be measured with a delay of about 20 to 30 minutes from the change of raw water until the instrument senses it. This has the great advantage that the effect of the response delay is much less than the feedback control method when measuring the turbidity of the supernatant water of the sedimentation tank. In addition, the ability to measure information obtained by operations that are very close to the behavior of actual sedimentation tanks is a significant advantage that allows for a much more accurate prediction of coagulation compared to the feed-forward control method, which is controlled by the raw water throughput and turbidity. There is.

In the following, description will be made mainly using the coagulation sedimentation treatment as an example.
A general form of the coagulation sedimentation apparatus has an apparatus configuration as shown in FIG. The raw water supplied from the raw water pump 1 enters the rapid agitation reactor 2, and polyaluminum chloride (PAC) or the like is added from the inorganic flocculant addition pump 3 and mixed and reacted with the inorganic flocculant by rapid agitation. Aggregates turbidity components. The agglomerated mixed solution produced from the rapid agitation reaction apparatus 2 enters the slow agitation reaction apparatus 4, and the polymer aggregating agent is added from the polymer aggregating agent addition pump 5, and the agglomerated solid is greatly grown by the agitation. When pH adjustment is necessary in the above process, an acid or alkali is added to maintain an appropriate pH for the aggregation reaction. Further, when the agglutination reaction is carried out by the agglutination reaction using only the cationic polymer flocculant, the agglutination reaction may be carried out only by the rapid stirring reaction apparatus 2. The mixed solution after completion of the coagulation reaction enters the coagulation sedimentation tank 6 and is separated into coagulated sludge and supernatant liquid, and the supernatant liquid is discharged from the precipitation tank trough 7 as treated water. Aggregated sludge is discharged from the bottom of the sedimentation tank. The inorganic flocculant and polymer flocculant addition pumps are driven by the outputs of the inverters 8 and 9, respectively.
The measurement management device 10 of the present invention starts by sampling a part of the mixed solution before the agglutination reaction is finished and entering the precipitation tank.

In FIG. 2, the structural example of the precipitation separation operation measurement management apparatus of this invention is shown.
The measurement management device 10 of the present invention includes a stationary sedimentation vessel 11, a vacuum pump 12 for sucking liquid into the stationary sedimentation vessel 11, an air release electromagnetic valve 13 for discharging the liquid, and a discharge flow rate control electromagnetic valve. 14, the discharge flow control orifice 15, the discharge line 16 at the bottom of the stationary sedimentation vessel 11, the sensor unit 17 of the turbidimeter for measuring the SS or turbidity of the liquid passing through the discharge line, for sampling the mixed liquid after the agglutination reaction An electromagnetic valve 18, a raw water sampling electromagnetic valve 19, a supernatant water sampling electromagnetic valve 20, and a drainage electromagnetic valve 21 are provided. The stationary sedimentation container 11 is sealed with an electromagnetic valve or the like, and a pressure sensor 22 for measuring the pressure in the container is installed. The tip of the solenoid valve 18 for sampling the mixed solution after the agglutination reaction is connected to the outlet of the slow stirring reaction device 4 so that the mixed solution after the agglutination reaction can be sampled. Although not shown, the raw water sampling solenoid valve 19 can sample raw water and the supernatant water sampling electromagnetic valve 20 can sample the treated water in the trough of the settling tank. It has become. A PC card 24 is mounted on the computer 23, and through the PC card, digital output, analog-to-digital conversion, and digital-to-analog conversion are performed, and the solenoid valve is turned on and off and the vacuum pump is operated to convert the turbidimeter. The measured values of the container 25 and the pressure sensor 22 are taken into the computer, and the control amount from the computer 23 is output to the inverters 8 and 9 of the flocculant addition pump.

The turbidimeter can be an optical sludge densitometer based on light transmission or reflection, an ultrasonic densitometer, or a microwave densitometer, but the agglomeration reaction is often aimed at clarifying the supernatant, so it is low. A densitometer that can measure turbidity is preferred. In the present embodiment, an optical sludge densitometer using the simplest laser beam transmission structure will be described as an example. Further, the sampling method may be a combination of a pump and a level sensor instead of a combination of a vacuum pump, a solenoid valve and a pressure sensor as in the above embodiment.

Next, the operation of the measurement management device 10 will be described.
After the stationary sedimentation container 11 is washed, the process starts from a state in which the washing water is discharged. From the state where all the solenoid valves are closed and the stationary sedimentation container 11 is sealed, the vacuum pump 12 is operated to reduce the inside of the stationary sedimentation container 11 to the set pressure P1. Next, the mixed solution sampling solenoid valve 18 after the aggregation reaction is opened, and the mixture after the aggregation reaction is sucked. Although the pressure of the stationary sedimentation vessel 11 changes due to the suction, the mixed solution sampling solenoid valve 18 is closed after the agglomeration reaction when the pressure P2 is reached. If there is no temperature change, the suction amount and space volume V0, P1, and P2 have the relationship of Equation 1, so the measured value of the pressure sensor 22 is taken into the computer and the solenoid valve is operated by digital output from the computer. Can be sucked in.
Suction volume = V0 (1-P1 / P2) (1)
After the suction, the air release solenoid valve 13 and the drainage solenoid valve 21 are opened, and the liquid in the stationary sedimentation container 11 is discharged. This operation is repeated as many times as necessary, and the liquid remaining in the pipe from the outlet of the slow stirring reactor 4 to the stationary precipitation vessel 11 is replaced with fresh liquid. Hereinafter, this operation is referred to as a replacement step. Immediately after completion of the replacement step, the vacuum pump 12 is operated to reduce the inside of the stationary precipitation vessel 11 to the set pressure P1, and then the mixed solution sampling solenoid valve 18 is opened after the agglutination reaction, and the mixed solution is aspirated. Then, a set amount of the mixed solution after the agglutination reaction is sampled in the stationary precipitation vessel 11. When the sampling is completed, the air-released electromagnetic valve 13 is opened, and the inside of the stationary sedimentation container 11 is allowed to stand at atmospheric pressure for a set time t. By standing, the mixed solution after the agglutination reaction is separated into precipitated sludge and supernatant. The stationary sedimentation container 11 of FIG. 2 shows the state isolate | separated into sedimentation sludge and supernatant liquid. After the elapse of time t, the air release solenoid valve 13 is closed, and the discharge flow rate control solenoid valve 14 and the drainage solenoid valve 21 are opened. The mixed solution after the agglutination reaction is discharged from the drain electromagnetic valve 21 via the discharge line at a substantially constant low flow rate according to the air resistance of the discharge flow control orifice 15. The liquid level and the sludge interface level of the stationary sedimentation vessel decrease while maintaining the relative position as they are discharged. The shape of the orifice of the discharge flow rate control orifice 15 is set in advance so that the discharge flow rate decreases while maintaining the relative position between the liquid level of the stationary sedimentation vessel and the sludge interface level. Although there are some differences depending on the shape of the stationary sedimentation vessel and the quality of the coagulated sludge, the relative position between the liquid level and the sludge interface level can be maintained approximately by reducing the liquid level to approximately 15 cm / min or less. The effluent is measured for transmitted light intensity with a transmitted light turbidimeter 17 set in the discharge line, and changes due to elapsed time are taken into the computer 23. Completion of liquid discharge is determined by analysis of transmitted light intensity or a set elapsed time, and the discharge flow rate control electromagnetic valve 14 and the drainage electromagnetic valve 21 are closed. Analyzing the transmitted light intensity change data captured by the computer 23 as described below, detecting the time that the sludge interface passes through, and calculating the sludge volume of the precipitated sludge from the discharge speed of the discharged liquid and the time that the precipitated sludge interface passes through In addition, the degree of compaction is judged from the data when the compacted sludge phase passes before the passing time of the sludge interface, and the turbidity of the supernatant is measured from the data when passing the supernatant liquid phase after the passing time of the sludge interface. .

The discharge speed of the discharged liquid is determined by the liquid viscosity, liquid level, orifice shape, drain pipe resistance, and the like. Since the shape of the orifice and the resistance of the drainage pipe are characteristics of the device, if the discharge time and discharge amount are measured in advance for each of the flocculated liquid mixture, raw water, and supernatant liquid, an approximate setting can be made. FIG. 16 shows the relationship between the discharge time, the discharge flow rate f1, and the integrated discharge amount f2. Differences that vary from measurement to measurement, such as the contamination of the orifice, the contamination of the drain pipe, and the temperature, and slightly affect the discharge flow rate can be corrected by the operation of claim 5. Of course, as a means for discharging the liquid, without using an orifice, the liquid may be discharged by a metering pump, or the inside of the container may be pressurized and pushed out by a constant discharge amount air pump.

  When raw water enters the sedimentation tank, when flocculant is added to flocculate turbidity or suspended solids, or when processing such as aeration is performed (corresponding to claim 2), the vacuum pump 12 and raw water sampling are used. After performing the replacement process using the electromagnetic valve 19, the raw water is sampled and discharged, and the transmitted light intensity when the raw water passes is measured by the transmitted light turbidimeter 17 to measure the turbidity.

When performing the operation corresponding to claim 3, after performing the replacement process using the vacuum pump 12 and the supernatant water sampling electromagnetic valve 20, the treated water is sampled and discharged from the settling tank trough, and the transmitted light turbidity The transmitted light intensity at the time of passing through the treated water is measured with a total 17 to measure turbidity.

The relationship between the transmitted light intensity Y and the turbidity in the transmitted light turbidimeter is as shown in the section G1 in FIG. 3 where the transmitted light intensity of the blank liquid with turbidity 0 is Y ₀ and the equation (2) is the absorbance. Since turbidity or SS and absorbance are in a linear relationship as shown in Equation (3) in the low turbidity range, turbidity can be measured with high accuracy. A blank solution with a turbidity of 0 has no practical problem even as the transmitted light intensity when passing through the washing water.
Absorbance = log (Y ₀ / Y) (2)
Turbidity = Coefficient x Absorbance (3)

After performing the above series of operations, although not shown, it is preferable to suck the washing water and wash the stationary precipitation container 11. The operation time is generally about 15 minutes for measuring the mixed solution after the agglutination reaction, 5 minutes for measuring the raw water turbidity, 5 minutes for measuring the treated water turbidity, and about 3 minutes for washing. By repeating this operation, it is possible to measure approximately every 20 to 30 minutes, and in practice, the state of aggregation can be measured at all times, and the amount of flocculant added can be appropriately controlled based on the data.
When performing claims 2 and 3, the order of measurement is preferably the same as the flow of the coagulation sedimentation operation: raw water turbidity measurement → measurement of the mixed solution after agglomeration reaction → treatment water turbidity measurement → washing.

FIG. 4 is a diagram showing an example of a change in transmitted light intensity in the case of a mixed solution after agglomeration reaction having a good aggregation state. FIG. 5 is a view showing a separation state in the stationary sedimentation container immediately before the discharge at that time.
The t1 interval in FIG. 4 is a change in transmitted light intensity when the consolidated sludge phase is passing.
The t2 interval is a change in transmitted light intensity when the sludge interface passes. The t3 interval is a change in transmitted light intensity when the supernatant phase passes. The t4 interval is a change in transmitted light intensity when the discharge is completed.
When passing through the sludge interface, the transmitted light intensity changes abruptly from small to large as in the t2 interval, and can be easily analyzed. For example, if the change curve is differentiated, it becomes as shown in FIG. 6 and the peak becomes the center of change, so that point can be determined as the sludge interface passage time ts. The relationship between the discharge time and the discharge amount is stored in advance in a computer, and the sludge volume from ts to the sludge interface passage can be calculated. If SV = 100 × sludge volume / sampling amount, SV is an important index for determining the agglomeration performance. The t1 interval before ts is the transmitted light intensity when the compacted sludge phase is passing, but generally in the transmitted light turbidimeter, the relationship between transmittance and turbidity (SS) exceeds the linear relationship range, Since it is in the G2 region of 3, the SS quantitative accuracy is poor, and it is difficult to determine the compaction from the SS quantitative value. The t3 interval after ts is the transmitted light intensity when the supernatant liquid phase is passing, and the turbidity of the supernatant can be measured from the transmitted light intensity of the stable region in the t3 interval, which is important for judging the aggregation performance. It becomes an indicator.

FIG. 7 is a diagram illustrating an example of a change in transmitted light intensity when part of the precipitated sludge floats. FIG. 8 is a view showing a separation state in the stationary sedimentation container immediately before the discharge at that time.
If the derivative of the change curve is taken, as shown in FIG. 9, when the sedimentation sludge passes through the interface, it becomes a positive peak, and when the floatation sludge passes through the interface, it becomes a negative peak. The passage time tf can be determined, and the sludge volume can be calculated from the relationship between the discharge time and the discharge amount. The sludge levitation phenomenon is caused by fine bubbles adhering to the sludge and floating as buoyancy.The cause of bubbles and the adhesion to sludge are not only the amount of flocculant added, but also the characteristics of the equipment and the properties of raw water. Since complicated factors are involved, it is necessary to elucidate the causal relationship in controlling the amount of flocculant added, but it greatly affects at least the precipitation separation performance in the settling tank. In the activated sludge treatment, if a denitrification reaction occurs in the sedimentation tank, nitrogen gas and the like are generated, which may cause a serious problem of sludge floating. Therefore, it is significant that this phenomenon can be measured at an early stage.

Next, an operation corresponding to claim 4 will be described.
FIG. 10 is a diagram showing an example of a change in transmitted light intensity in the case of a mixed solution after agglomeration reaction having poor compactness. Moreover, FIG. 11 is a figure showing the isolation | separation state in the stationary sedimentation container immediately before discharge | emission at that time. The characteristic of the transmitted light intensity change at this time is that the sludge interface passage time ts is specified by the same analysis as described above, and the transmitted light intensity in the previous t1 section is not a smooth change as in FIG. It is a variation to the value. In the case of sludge with poor compaction, the coagulated sludge adheres in the stationary state, but when the liquid is discharged, the sludge phase is pulled down and separated into small blocks, This is a phenomenon that occurs because the liquid passes through the sensor part of the turbidimeter with the clear liquid entering (see FIG. 11). The worse the compactness, the more pronounced this phenomenon becomes, and the larger the variation, so the compactness can be evaluated by the size of the variation.
In such a case, since the consolidated sludge swells, the SV value calculated from the sludge interface passage time ts is slightly larger than the SV value in the stationary state, but if the compactness is poor, the SV value is higher. Since it becomes larger and the evaluation is in the same direction, it does not hinder the judgment.

FIG. 12 is a diagram showing a specific example in which the compactness is evaluated from the change in transmitted light intensity in the case of a mixed liquid after agglomeration reaction with very good compaction. The circles in the figure are transmitted light intensity values obtained by sampling changes in transmitted light intensity every second. The solid line in the time range θ seconds in which the sludge phase passes is the simple regression line Y = b1 as a result of the single regression analysis with the discharge time as the explanatory variable X and the transmitted light intensity value at that time as the target variable Y. -X + b0. The size of the variation can be evaluated by, for example, an error σ per unit time obtained by dividing the squared product sum Σε _i ² of the residual ε _i from the calculated value of the single regression line by θ. In the precipitated sludge phase of the mixed liquid after the coagulation reaction with very good compaction, the variation is small, σ = 17 in FIG.

FIG. 13 is a diagram showing a specific example in which the compactness is evaluated from a change in transmitted light intensity in the case of a mixed liquid after agglomeration reaction with relatively good compaction. The circles in the figure and the solid line in the range through which the sludge phase passes are the same as described above. The variation in FIG. 13 is larger than that in FIG. 12 and σ = 64.

FIG. 14 is a diagram showing a specific example in which the compaction is evaluated from the change in transmitted light intensity in the case of the mixed solution after the aggregation reaction having poor compaction. The circles in the figure and the solid line in the range through which the sludge phase passes are the same as described above. The variation in FIG. 14 is very large and σ = 160.

FIG. 15 is a graph showing the relationship between the amount of flocculant added to the same raw water, supernatant turbidity, SV, and compactness. In FIG. 15, the consolidation is shown as 1 / σ. As shown in the figure, the turbidity of the supernatant decreases as the amount of the flocculant added increases, and a good treated water can be obtained. However, when the amount exceeds the appropriate amount, the turbidity does not decrease so much. Also, SV increases and the compactness deteriorates. In a range exceeding the proper amount, the compactness evaluation according to the present invention has a larger change than the change in SV, and there is an advantage that the tendency becomes clear. In addition, since SV is affected by the raw water turbidity, the amount of coagulant added, and the compactness, when the turbidity of the raw water changes, it is difficult to determine the compactness from the change in SV. When the amount of flocculant added is controlled to an appropriate amount, deficiency of flocculant can be easily determined from the supernatant turbidity, but in the case of excess, the supernatant turbidity changes little and is difficult to judge. If this method is used, there is a great effect that can be properly evaluated even if there is a fluctuation in the raw water. Consolidation is an important indicator in the precipitation separation operation together with the SV value, and is strongly related to sedimentation in the presence of slight flow as in an actual precipitation tank. Moreover, if denitrification occurs in bulking by a filamentous fungus or a sedimentation tank in activated sludge treatment, the compactness is significantly reduced, and it is significant to evaluate the compaction.

  Next, an embodiment corresponding to claim 5 will be described. In FIG. 4, the transmitted light intensity L0 when the cell of the turbidimeter sensor runs out of air and the air enters the cell gap is less than the transmitted light intensity L2 when the cell is full of supernatant due to scattering. descend. Even if there is no sludge floating when the liquid is discharged, the sludge deposited and deposited on the tapered portion of the bottom of the stationary sedimentation vessel is washed away by the flow of liquid just before the liquid discharge ends, so the transmitted light intensity is Once it is lowered, the discharge ends. Therefore, a change in the vicinity where the liquid is completely discharged is a change from the end of t3 to t4 in FIG. A change obtained by differentiating this is a change from the end of t3 to t4 in FIG. 6 and can be detected from a negative peak followed by a positive peak. When there is almost no sludge deposit on the taper portion, the positive peak becomes small and it may become almost inconspicuous, but the negative peak remains. The transmitted light intensity L0 when air enters the cell gap can be measured in advance. By storing it in the computer, the peak is detected by the change in the differential, and then the measured value of t4 from the end of t3 in FIG. If the value becomes constant at about L0, it can be determined that the discharge is completed.

If the discharge time of the liquid can be detected automatically, operate the vacuum pump and solenoid valve from the pressure value, charge an arbitrary amount of sample liquid, and automatically measure the discharge time for the charged amount, then the discharge flow rate calibration curve It is possible to correct the discharge speed by changing the property of the solid-liquid mixture by measuring the discharge time of the liquid with respect to the amount charged constant amount during measurement, and clogging It is also possible to detect device abnormalities.

If the method of this invention is used, the addition amount of a coagulant | flocculant can be controlled appropriately. The basis is information on the supernatant turbidity, SV, and sludge phase consolidation that can be obtained in claims 1 and 4. If the supernatant water turbidity is used for the control in the sedimentation tank, there is a response delay of 1 hour to several hours even in the case of coagulation sedimentation, so correction is necessary.In the case of raw water with large fluctuations, it is not easy to control appropriately. Although there is no correlation between the supernatant turbidity and the supernatant turbidity in the actual sedimentation tank, it can be measured in about 15 minutes after sampling, so the response delay error is greatly reduced. In addition, if turbidity information of raw water is obtained according to claim 2, the feedwater turbidity information is fed forward with the turbidity information of raw water based on the appropriate amount of flocculant calculated from the supernatant turbidity, SV and the compactness of the sludge phase. Corrections can be added. Further, if the supernatant water turbidity information is obtained in claim 3, the control result can be verified, and the control reliability is increased. In the embodiment, the measured value of the turbidimeter converter 25 is taken into the computer 23, the control amount is calculated by the computer 23, digital-to-analog conversion is performed by the PC card, and the control amount is supplied to the inverters 9 and 10 of the flocculant addition pump. Output, control the amount of flocculant added, or generate an alarm with a digital output PC card.

  The present invention is not limited to precipitation separation by gravity, such as solid-liquid separation in coagulation sedimentation and activated sludge sedimentation, but is also used for evaluation and optimization of operations where coagulation action is a key point such as coagulation flotation and sludge dewatering Is possible.

It is a figure which shows the flow of a coagulation sedimentation processing apparatus. It is a figure which shows the flow of the example of an apparatus of this invention. It is a figure which shows the relationship between the transmittance | permeability in a transmitted light type densitometer, SS, or turbidity. It is a figure which shows the example of the change of the transmitted light intensity in the case of the liquid mixture after agglomeration reaction with a favorable aggregation state. It is a figure showing the isolation | separation state in the stationary precipitation container immediately before discharge | emission in the case of the liquid mixture after agglomeration reaction with favorable aggregation state. It is the figure which differentiated the change curve of the transmitted light intensity in the case of the liquid mixture after agglutination reaction with a favorable aggregation state. It is a figure which shows the example of a change of the transmitted light intensity | strength when a part of sedimentation sludge floats up. It is a figure showing the isolation | separation state in the stationary sedimentation container immediately before discharge | emission when a part of sedimentation sludge floats up. It is the figure which differentiated the change curve of the transmitted light intensity when a part of sedimentation sludge surfaced. It is a figure which shows the example of the change of the transmitted light intensity in the case of the liquid mixture after aggregation reaction with bad compactness. (A) It is a figure showing the isolation | separation state in the stationary sedimentation container immediately before discharge | emission in the case of the liquid mixture after aggregation reaction with bad compactness. (B) It is a figure which shows the behavior of the sludge phase in the stationary sedimentation container at the time of discharge | emission. It is a figure which shows the specific example which evaluates compaction from the change of the transmitted light intensity in the case of the liquid mixture after agglomeration reaction with very good compaction. It is a figure which shows the specific example which evaluates compaction from the change of the transmitted-light intensity | strength in the case of the mixed liquid after a coagulation reaction with comparatively good compaction. It is a figure which shows the specific example which evaluates compaction from the change of the transmitted light intensity | strength in the case of the liquid mixture after agglomeration reaction with bad compaction. It is a figure which shows the relationship between the coagulant | flocculant addition amount, the turbidity of a supernatant liquid, SV, and a pressure density. It is a figure which shows the relationship between the discharge time from a stationary sedimentation container, discharge speed, and discharge | emission integrated amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water pump 2 Rapid stirring reaction apparatus 3 Inorganic flocculant addition pump 4 Slow stirring reaction apparatus 5 Polymer flocculant addition pump 6 Coagulation sedimentation tank 7 Precipitation tank trough 8, 9 Inverter 10 Measurement management apparatus 11 Stationary sedimentation container 12 Vacuum Pump 13 Open-air solenoid valve 14 Discharge flow control solenoid valve 15 Discharge flow control orifice 16 Discharge line 17 Transmitted light turbidimeter 18 Solenoid valve for coagulation reaction sampling 19 Solenoid valve for raw water sampling 20 Solenoid valve for supernatant water sampling 21 Discharge solenoid valve via discharge line 22 Pressure sensor 23 Computer 24 Card 25 Turbidimeter converter

Claims (6)

In a water treatment system that precipitates and separates turbidity or suspended solids by standing waste water containing suspended turbidity or suspended solids (hereinafter referred to as raw water),
A first step of charging a set amount of the solid-liquid mixture before entering the precipitation tank into a stationary precipitation vessel;
A second step of discharging the liquid while maintaining the relative position between the liquid level of the stationary precipitation container and the sludge interface level after standing for a set time;
A third step of measuring the elapsed discharge time during discharge and the suspended solids or turbidity of the effluent;
A fourth step of detecting at least the time during which the precipitated sludge interface passes from the measured value, and calculating the sludge volume of the precipitated sludge from the discharge speed of the discharged liquid and the time through which the precipitated sludge interface passes;
A fifth step of measuring the turbidity of the supernatant liquid phase from the measured value after passing through the precipitated sludge interface;
A method for measuring and managing a precipitate separation operation, comprising: Before raw water enters the sedimentation tank, when flocculant or the like is added to flocculate turbidity or suspended solids or a process such as aeration, in addition to the first step,
The precipitation separation operation measurement management method according to claim 1, comprising a step of charging raw water in a stationary sedimentation vessel and a step of measuring suspended solids or turbidity of the raw water. In addition to the first step, the method further comprises a step of charging the supernatant water of the sedimentation tank to the stationary sedimentation vessel, and a step of measuring suspended solids or turbidity of the supernatant water. 2. The method for measuring and controlling the precipitation separation operation described in 1. In the third step, the method further includes a step of judging whether the sedimentation sludge phase is compacted from the magnitude of variation in the measurement value of suspended solids or turbidity when the sedimentation sludge phase is passing through. The precipitation separation operation measurement management method according to claim 1. In the third step, liquid discharge completion is detected from the change in the measured amount when the cell that measures suspended solids or turbidity is full and the measured amount when the cell runs out of liquid. The method according to claim 1, further comprising a step of measuring a liquid discharge rate. Precipitation separation operation measurement management used in a water treatment system that precipitates turbid or suspended solids by allowing raw water to stand,
Means for charging a set amount of the solid-liquid mixture before entering the precipitation tank into the stationary precipitation container;
Means for discharging the liquid while maintaining the relative position between the liquid level of the stationary sedimentation container and the sludge interface level after standing for a set time;
Means for measuring the elapsed time of discharge during discharge and the suspended solids or turbidity of the effluent,
Means for detecting at least the time during which the precipitated sludge interface passes from the measured value, and calculating the sludge volume of the precipitated sludge from the discharge rate of the effluent and the time through which the precipitated sludge interface passes;
Means for measuring the turbidity of the supernatant liquid phase from the measured value after passing through the sedimentary sludge interface;
A precipitation separation operation measurement management device comprising:

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