JP2009022865A - Precipitation status measuring method in water treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method allowing stable wastewater treatment by early detecting precipitation defect in a gravity precipitation solid/liquid separation operation. <P>SOLUTION: Sludge concentration at a plurality of points in the vertical direction in a precipitation tank is measured at a timing linking with the movement of a sludge scraper. When a deviation value of the sludge concentration distribution below the sludge interface, or an aging variation rate of the deviation value exceeds thresholds set respectively in advance, the precipitation defect is determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention measures whether or not the operation of leading the waste water to the sedimentation tank and precipitating and separating the floating solid is properly performed in the water treatment system for separating the turbidity or the floating solid in the waste water by gravity precipitation. The present invention relates to a measurement method that contributes to stabilization of wastewater treatment.

  The operation of guiding wastewater containing suspended solids to the sedimentation tank and separating it by gravity sedimentation is a basic technology widely used in activated sludge treatment and coagulation sedimentation treatment. It is important to manage the precipitate separation state. In the laboratory, there is a method for managing the sedimentation rate of sludge using an index such as sludge volume (SV) or sludge volume index (SVI) in a sludge sedimentation test in a cylinder. The amount of mixed liquid flowing into the sedimentation tank, the concentration of suspended solids in the liquid mixture, the concentration and discharge of suspended solids in the supernatant, the concentration and discharge of suspended solids in the discharged sludge, There is a method for measuring and managing the position of the sludge interface between the supernatant liquid phase and the sludge phase. In particular, the measurement control of the position of the sludge interface is used as an index that directly reflects the result of the actual sedimentation operation.

  As automatic instruments for measuring the concentration of sludge in a mixed liquid, instruments utilizing light transmittance and reflectance, instruments utilizing ultrasonic waves, and the like have already been widely put into practical use. For instruments that automatically detect and measure the sludge interface in the sedimentation tank, devices that have already been put to practical use, such as moving the sludge concentration meter up and down mechanically in the sedimentation tank and detecting the sludge interface from the position and concentration data, etc. There is. If these instruments are used, it is possible to manage and grasp to a certain extent whether or not the operation of the settling tank is being performed appropriately.

However, if the sludge interface rises, it is not sufficient to investigate the cause by detecting the sludge interface or the sludge concentration or the precipitated sludge concentration of the mixed liquid flowing into the settling tank.
For example, in activated sludge treatment, factors that determine the sludge interface include operating factors such as the inflow amount and the balance between the inflow sludge amount and the discharged sludge amount, but the sedimentation factor of the sludge itself is also greatly affected. Factors that determine the sedimentation property of sludge include (a) electrochemical factors such as the charged state of suspended solid particles in the mixed solution, (b) sludge floc formation state, (c) sludge filamentous fungi, etc. There are various factors, such as the factors of biota due to generation, (d) buoyancy effect due to generation of bubbles due to decay in the sedimentation tank, and (e) buoyancy effect due to generation of bubbles due to denitrification reaction in the precipitation tank.

  In particular, the buoyancy effect due to the generation of air bubbles in the denitrification reaction in (e) causes the sludge interface to rise when this phenomenon occurs. May become impossible. In activated sludge treatment, there is always a potential danger of this trouble, and the situation of the sedimentation tank may change drastically in a short time of several hours to one day. Moreover, once the sludge levitation phenomenon occurs due to a delay in response, it is difficult to restore normal operation with a measure of adding a flocculant, and it is necessary to significantly reduce the throughput while removing the levitation sludge. Become. In addition, this is a phenomenon that requires great attention in the operation of activated sludge. For example, it takes a considerable number of days to restore the treatment capacity due to the sludge flowing out.

  The mechanism of this phenomenon is that the activated sludge mixed solution flowing into the sedimentation tank contains a large amount of nitrate ions produced by nitrifying bacteria in the raw water or in the aeration tank. When the BOD material flows into the sedimentation tank, nitrate ions become nitrogen gas and adhere to the sludge by the action of denitrifying bacteria in the sedimentation tank, resulting in buoyancy that lowers sedimentation or floats. Is. However, in the actual machine, there is a time delay of the phenomenon in the settling tank with respect to fluctuations in raw water and changes in operating conditions, and there are various factors that affect the settling in the settling tank. Requires considerable skill and skill.

In order to specify that the cause of poor precipitation separation in the settling tank is due to the progress of the denitrification reaction in the sludge phase of the settling tank, the conventional change measurement control of the position of the sludge interface has been used. Inadequate and another measurement analysis method is required.
As a conventional technology, the mixed liquid sampled at the outlet of the activated sludge aeration tank or the coagulation sedimentation reaction tank is transferred to the cylinder in the measuring instrument, and the turbidity is measured while extracting the sludge that has settled and settled in the cylinder from the bottom of the cylinder. And the technique of measuring the sedimentation state of the sludge in a cylinder is disclosed (for example, patent document 1). Although this technology is significant in that it measures the sludge concentration inside the sludge phase and analyzes the sludge settling state from the results, it is a completely stationary cylinder in a separate device from the actual settling tank. Is used to analyze the compactness, and may not always match the actual sedimentation state of the sedimentation tank.

As another technique, a method using a pH meter provided at a sludge interface in a sedimentation tank is disclosed (for example, Patent Document 2). This technique utilizes the fact that the pH value changes at the sludge interface, but only detects the sludge interface. Moreover, a change of about 0.08 is detected as a pH value in a batch type sedimentation tank, and in a sedimentation tank with flow like a standard activated sludge sedimentation tank, it is a fluctuation to detect the difference in the degree. Is difficult.
JP 2006-175357 A JP 07-294310 A

  The present invention analyzes the sedimentation state of sludge by measuring the concentration of suspended solids in the vertical direction, pH value or nitrate ion concentration in the sedimentation tank, and gravity precipitation solid-liquid separation in activated sludge treatment and coagulation sedimentation treatment An object of the present invention is to provide a measurement method that enables stable wastewater treatment by managing the operation status in operation and detecting early sedimentation defects.

The gist of the present invention is as follows. That is,
(1) In a water treatment system that separates turbidity or suspended solids in wastewater by gravity sedimentation, the sludge concentration at a plurality of vertical positions in the settling tank is measured at the timing linked with the movement of the sludge squeezer. Precipitation characterized by determining that the deviation value of the sludge concentration distribution below the sludge interface, or the time change rate of the deviation value exceeds a predetermined threshold value (Z1 or Z2) for each, is a sedimentation abnormality. State measurement method.
In the present invention, the “sludge interface” refers to a boundary between the supernatant liquid phase and the sludge phase and a position where the sludge concentration in the sedimentation tank changes remarkably.
In the present invention, the “deviation value” is an index for evaluating the magnitude of a random increase / decrease change in the sludge concentration below the sludge interface, and the deviation from the average value, the minimum value of the sludge phase concentration, Examples include the width of the maximum value. Also, as will be described later, the distance from the sludge interface toward the bottom is set as the explanatory variable x, the sludge concentration is set as the objective variable y, a single regression analysis is performed, and the sum of squares of the residuals from the single regression equation is calculated. It is also possible to use a method for evaluating the size.

(2) In addition to the above condition (1), the pH value (pH1, pH2) in the supernatant liquid phase and sludge is measured in accordance with the measurement of the sludge concentration, and the pH value or pH value of both is measured over time. A sedimentation state measuring method, characterized in that a sedimentation abnormality is determined when a relative comparison value of change rates exceeds a predetermined threshold value (Z3 or Z4).
In the present invention, the “relative comparison value” is an index for relativizing and comparing pH1 and pH2, for example, the difference between the pH values (pH1-pH2) or the ratio (pH1 / pH2), Or it is the concept including the time change rate of these values.

通常、活性汚泥における沈殿槽での汚泥相内では嫌気状態となり、好気状態にある曝気槽内の混合液の状態とは異なる状態となるため、沈殿槽内の上澄液相と汚泥相のｐＨ値は若干異なることが多い。しかしながら両者のｐＨ値の変化は、曝気槽内での廃水の処理状況などにより変化する。たとえば曝気槽で処理未了のＢＯＤ成分が多い場合には、沈殿槽内でも処理が進行し、有機酸が多い場合にはｐＨ値がアルカリサイドに変化し、アミン成分が多い場合にはｐＨ値は酸性サイドに変化する。また生物活動で発生する炭酸ガスはアルカリを中和する方向に働き、沈殿槽内で嫌気性菌が活動すると有機酸が発生し、ｐＨ値が酸性サイドに変化する。このように変化は一律ではないが、脱窒反応が起きれば汚泥相のｐＨ値は上澄液相のｐＨ値より、通常時の変化より確実にアルカリサイドにふれ、脱窒反応が活発におきれば明確な差となる。但し振れ幅の大きさは、上記理由により一律ではなく、ｐＨ値変化のみで脱窒反応の有無を判定するには、通常の変動なのか、脱窒反応によるものか判定には決定力不足である。 The action of denitrifying bacteria in the sludge phase of the sedimentation tank is as follows. When methanol is used as a hydrogen donor, the denitrification reaction proceeds as shown in equation (1), generating hydroxide ions, and adjusting the pH value of the liquid. Change to alkali side.

Normally, activated sludge is anaerobic in the sludge phase in the settling tank, and is in a different state from the mixed liquid in the aerobic aeration tank. The pH value is often slightly different. However, the change in pH value of the two changes depending on the treatment status of wastewater in the aeration tank. For example, if there are many unprocessed BOD components in the aeration tank, the processing will proceed in the precipitation tank. If there are many organic acids, the pH value will change to the alkali side, and if there are many amine components, the pH value will change. Changes to the acidic side. Carbon dioxide generated by biological activity acts to neutralize the alkali. When anaerobic bacteria are activated in the sedimentation tank, an organic acid is generated, and the pH value changes to the acidic side. In this way, the change is not uniform, but if a denitrification reaction occurs, the pH value of the sludge phase touches the alkali side more reliably than the normal phase, and the denitrification reaction is more active. If it comes, there will be a clear difference. However, the magnitude of the swing width is not uniform for the above reasons, and it is not decisive to judge whether the denitrification reaction is due to the normal fluctuation or the denitrification reaction to determine the presence or absence of the denitrification reaction only by the pH value change. is there.

However, if the pH value fluctuates to the alkali side more than the fluctuation range of the normal pH value in a state where the sludge concentration in the sludge phase varies, the probability that the denitrification reaction occurs is very high. In addition, since the amplitude of the normal pH value can be predicted to some extent, the amplitude is stored in advance as the set value A, and the pH 1 of the supernatant liquid phase at the time of measurement and the pH 2 inside the sludge interface are measured. For example, when (pH2−pH1)> A, it can be recognized that a denitrification reaction that affects sedimentation occurs. Even if the set value A is not used, if a value such as (pH2-pH1) or pH2 / pH1 increases with the elapsed time, it can be determined that there is a high probability that the denitrification reaction is expanding.
Whether it is expanding or not can be determined from the measurement time of several points and a value such as (pH2-pH1) or pH2 / pH1, and a simple regression equation can be obtained, and it can be determined from the sign of the regression coefficient whether it is expanding or not.

(3) In addition to the conditions of (1) above, in addition to the measurement of sludge concentration, the nitrate ion concentration in the supernatant liquid phase and sludge is measured, and the nitrate ion concentration or the temporal change rate of the nitrate ion concentration of both is measured. A sedimentation state measuring method, wherein when the relative comparison value of each exceeds a predetermined threshold value (Z5 or Z6) for each, it is determined that there is a sedimentation abnormality.
The concept of “relative comparison value” is the same as (2) above.

As shown in the above equation (1), if a denitrification reaction occurs in the sludge phase, the nitrate ion concentration decreases. Therefore, if the nitrate ion concentration in the supernatant liquid phase and the sludge phase is measured, and the nitrate ion concentration in the sludge phase is lower than the nitrate ion concentration in the supernatant liquid phase, evidence that a denitrification reaction has occurred in the sludge phase. Thus, the magnitude of the denitrification reaction can be estimated from the decrease.
Theoretically, if the nitrate ion concentration in the supernatant and sludge can be measured accurately and quickly, the degree of denitrification reaction can be measured by itself. The nitrate ion electrode is the instrument that can easily and continuously measure nitrate ion, which is currently in practical use, but its performance is affected by the coexistence of chloride ions and a small amount of anionic surfactant. is there. In particular, in activated sludge mixed liquids in which various interfering substances such as wastewater treatment change indefinitely, reliable values are not always obtained, and in order to determine the denitrification reaction based only on the nitrate ion concentration value It is not reliable.

  However, in the case of wastewater that has a small degree of interference and that can be identified in practice, the nitrate concentration in the sludge phase is lower than the nitrate concentration in the supernatant liquid phase in a state where the sludge concentration varies. In some cases, the probability that a denitrification reaction has occurred is very high. In such a case, by adding a phenomenon due to the nitrate ion concentration, the sensitivity is improved as compared with the case where the denitrification reaction is determined only by the variation in the sludge concentration, and the decrease can be reliably detected earlier. In such a case, even if it is determined that the sedimentation abnormality is caused by the denitrification reaction, an appropriate measure can be taken without any practical problem. The specific determination is the same as the method based on the pH value.

According to the present invention, the precipitation separation operation can be appropriately managed, and troubles due to poor sedimentation can be avoided.
According to the present invention, both the detection of the sludge interface and the change in suspended solids concentration can be measured in a state in which the influence of the sludge phase disturbance due to the sludge squeezing is excluded by measuring at the timing linked with the rake movement. it can. Thereby, the abnormality with respect to gravity precipitation operation in a sedimentation tank is recognized at an early stage, the operation state of a sedimentation tank is stabilized, and favorable treated water is obtained.

Hereinafter, an embodiment of the present invention will be described with an example of precipitation treatment in activated sludge.
The activated sludge treatment system 1 according to the present embodiment has a device configuration as shown in FIG. The waste liquid supplied from the raw water pump 6a enters the aeration tank 7, the air from the blower 3 is aerated with the activated sludge mixed liquid by the diffuser pipe 4, the pollutants in the waste water are decomposed and removed, and enters the precipitation tank 5. The mixed liquid is separated into sludge and supernatant water, the supernatant liquid is discharged as treated water, and the sludge is returned to the aeration tank by the return sludge pump 6b. Sludge proliferated by removing the contaminants in the wastewater is discharged out of the system by the excess sludge extraction pump 6c. A precipitation separation state measuring device is attached to the side surface of the precipitation tank 5.

In FIG. 2, the structure of the precipitation separation state measuring apparatus 2 is shown.
The precipitate separation state measuring device 2 includes a sampling device unit 2a, a measuring unit 2b, and a data processing unit 2c. The data processing unit 2c includes a computer 8 and a terminal board 9. The data processing unit 2c analyzes measurement data from the measurement unit 2b, and operates a sampling device unit 2a, a lifting device of the measurement unit 2b, a pump, and the like. The sampling device section 2a is composed of a flexible sampling tube 10 to be inserted into the settling tank, an elevating rope 12 with a weight 11 at the tip, and a winding device 13 for driving the elevating rope. The tip of the sampling tube 10 is fixed to the weight 11. The winding device 13 is driven by a command from the computer 8, and the lifting rope 12 is moved up and down in the vertical direction in the settling tank, thereby moving the tip of the sampling tube up and down in the vertical position in the settling tank. The measuring unit 2b is equipped with a suction pump 14, and takes the sample solution from the sampling tube 10 in the sedimentation tank into the measuring unit 2b. A pH meter 16 and a sludge concentration meter 17 are installed in the measurement channel 15 as measuring instruments. The computer 8 takes in the measurement data from the pH meter or the sludge concentration meter via the terminal board 9 and takes in the vertical position information of the sedimentation tank of the sampling tube 10 based on the driving state of the winding device 13.

As the sludge densitometer 17, an optical sludge densitometer based on light transmission or reflection, an ultrasonic densitometer, a microwave densitometer, or the like can be used. In addition, the method for measuring the sludge concentration in the vertical direction in the sedimentation tank is as follows: even if the tip of the sampling tube is moved up and down in the sedimentation tank as in the above example, the sludge concentration sensor is moved up and down in the sedimentation tank. Also good. Although not shown, if the pH meter 16 is replaced with a nitrate ion electrode, the nitrate ion concentration corresponding to claim 3 can be measured.

Next, the operation of the measuring device 2 will be described.
In the measurement, the sampling measurement timing is first adjusted. There are several causes of the sludge phase disturbance, but the influence of the sludge scraper is very large. The turbulence of the sludge phase becomes maximum when the scouring member of the sludge squeezer passes and becomes minimum before the next passage. Since the sludge scraper rotates periodically, the disturbance of the sludge phase is a periodic change. The vertical position in the settling tank when the sludge phase becomes less disturbed between the passage of the sludge scraping member and the passage of the next sludge scraping member in accordance with the passage cycle of the sludge scraping device. For example, the sludge concentration is sampled from the surface of the sedimentation tank water level toward the bottom, measured with a pH meter and a sludge concentration meter, and the measurement data is taken into the computer together with the positional information in the sedimentation tank.

The change in the sludge concentration data can be easily specified by passing the sludge interface so that the sludge concentration changes rapidly as shown by the curve a in FIG. When analyzing and calculating with a computer, if the rate of change in the sludge concentration is calculated, a large peak is obtained as shown in FIG. 4, so that the sludge interface can be easily identified.

In an ideal situation where there is no flow or other fluctuations in the settling tank, if no bubbles are generated due to denitrification in the settling tank, the concentration change in the sludge phase is directed from the sludge interface to the bottom of the settling tank. As a result, the sludge concentration gradually increases smoothly as shown by curve a in FIG. 3 and curve a in FIG. For example, even when the amount of water flowing into the settling tank increases and the sludge interface rises, the sludge concentration decreases from the sludge interface toward the bottom of the settling tank, although the absolute value of the sludge concentration decreases as shown by the curve b in FIG. The smoothly increasing change is maintained. Further, even when sedimentation deteriorates due to changes in the floc formation state of sludge, changes in the charge state of suspended solids, increases in filamentous fungi, etc., the absolute value of the sludge concentration decreases as shown by curve c in FIG. However, the change in which the sludge concentration gradually increases smoothly from the sludge interface toward the sedimentation tank bottom is maintained. On the other hand, when a denitrification reaction occurs in the sludge phase, turbulence due to intermittent bubble rise, sludge with attached or unattached bubbles are unevenly distributed from the sludge interface to the sedimentation tank. The sludge concentration becomes a random increase / decrease change as shown by a curve d in FIG. 4 toward the bottom. As the denitrification phenomenon becomes larger, the random increase / decrease change becomes larger as shown by the curve e in FIG. 4, and when partial sludge floating occurs, the sludge concentration partially equal to the supernatant liquid phase as shown by the curve f. Appears. Eventually, the sludge interface is destroyed, and the sludge rises as shown by curve g. 5 to 8 schematically show the state of such a sludge phase. FIG. 5 shows a curve a in FIG. 4, FIG. 6 shows a curve d and e, and FIG. 7 shows a curve f. FIG. 8 corresponds to the curve g.

As an index indicating the magnitude of the random increase / decrease change, evaluation can be made using the deviation from the average value, or the width of the minimum and maximum values of the concentration in the sludge phase. The distance from the bottom to the bottom is the explanatory variable x, the sludge concentration is the objective variable y, simple regression analysis is performed, the deviation from the single regression equation is calculated, and the evaluation method based on the magnitude is preferable because the error is small. .

Hereinafter, a measurement method in an actual sedimentation tank will be described by an example in which a sampling tube is attached to the edge of the trough of the circular sedimentation tank and the vertical direction in the sedimentation tank is sampled. The settling tank is a settling tank for standard activated sludge (diameter 12 m, volume 300 m3). In FIG. 9, the time-dependent (t = t1-t4) change of the sludge density | concentration in the sedimentation tank vertical direction in the sampling position P is shown. The relative positional relationship between the rake arm and the sampling position is shown as P (t1) to P (t4) in FIG.
The concentration change in the vertical direction of the settling tank is caused by the sludge phase lower part being disturbed by the passage of the sludge scraping member of the rake arm. Immediately before passing through the sludge scraping member, the concentrated sedimentary sludge is pressed to become a curve shown in FIG. Since thick sediment sludge wraps around, it becomes as shown in the figure (b). As the flow stops after the passage, sludge settles at the bottom, as shown in FIG. 6C, and approaches the ideal concentration distribution as shown in FIG. Further, the above change is repeated by the approach of the next sludge scraping member.

Now, the single regression analysis is performed with the distance from the sludge interface to the bottom direction as the explanatory variable x and the sludge concentration as the objective variable y, and the sum of squares Σ (y _i −bx _i − of the single regression equation Y = bx + a a) When ² is calculated, the sum of squares of the residual becomes a periodic change that becomes maximum immediately after passing the scraping member and becomes minimum before passing the next scraping member. In the case of a circular sedimentation tank for activated sludge, the sludge scraper rotates once in 30 minutes to 1 hour, and the scraper member is attached to the rake arm, so this period is about 15 to 30 minutes.
As shown in FIG. 11, the deviation immediately after passing the scraping member (corresponding to the sum of squares of the residual) is very large, and is much larger than the deviation of the sludge phase turbulence to the extent that the sedimentation due to bubble generation is inhibited. The cause cannot be identified from the deviation. However, if the flow after the passage is cured, the deviation becomes small, so that it can be discriminated. Therefore, the object can be achieved by measuring the sludge concentration in the vertical direction of the settling tank after a set time (hereinafter, measurement start set time) after the scraping member passes.

The time at which the scraping member passes can be easily specified by the following operation, for example. That is, after measuring the sludge concentration in the vertical direction of the sedimentation tank, the tip of the sampling tube is returned to the fixed position, and the concentration change is continuously measured. Since the concentration change is the sludge concentration at the position of the one-dot chain line in FIG. 9, if the concentration is plotted on the vertical axis with the passage of time as the horizontal axis, as shown in FIG. Change. Using the specified time as a reference, after the measurement start set time, the tip of the sampling tube is moved to the surface of the precipitation tank water level, and measurement is performed while moving the sampling tube toward the bottom of the precipitation tank.

When descending from the surface water level of the settling tank to the bottom of the settling tank at a rate of about 0.5 m per minute, the depth of the activated sludge settling tank is usually about 3 to 4 m, so about 6 to 8 minutes. Can sample from the surface to the bottom of the settling tank. After the sampling position reaches the bottom of the sedimentation tank, the lifting rope is wound up in the pulling direction, the sampling position is returned to the fixed position, and sampling is continued. The measurement start setting time is set so that the sampling tip position reaches the bottom of the sedimentation tank before the sludge phase is disturbed by the next scraping member.
FIG. 13 shows the movement of the tip position of the sampling tube.

Even when the sedimentation operation is performed in a normal state, there is a slight deviation in sludge concentration change due to the flow of the entire sedimentation tank, the residual effects of the sludge scraper disturbance, the locality of the sludge floc state, etc. Therefore, it is practical to store the deviation value determined as the normal operation range in advance as a set value (threshold value) and compare it with the set value.

Further, even if the set value is not used, if the deviation value increases with the elapsed time, the probability of the influence of air bubbles is high rather than the influence of the sludge scraper.
Since the frequency of measurement is about 20 minutes in the embodiment, if the deviation value is plotted with respect to the elapsed time, even if there is some variation in each point, the whole direction can be calculated if there are several points of data. When data processing is performed by a computer, a single regression equation can be obtained from several measurement times and deviation values, and it can be determined from the sign of the regression coefficient of the equation whether or not the deviation value tends to expand.

The causes of bubbles in the sedimentation tank include denitrification, generation of methane gas due to partial decay due to sludge accumulation, and the introduction of fine bubbles from the aeration tank. Judgment from the value of the variation in the sludge concentration described above cannot identify the cause of bubbles, but there is no doubt that it is a factor that inhibits sedimentation. According to the measurement method of the present invention, it is possible to detect an abnormality at an earlier stage than in the prior art that manages only the trend of the sludge interface.

  The present invention is not limited to gravity separation such as solid-liquid separation in measurement sedimentation in a sedimentation tank of activated sludge, but also gravity-precipitates organic pollutants in which there is always a risk of bubble formation due to microbial reactions. It can also be used for state management of an apparatus (for example, an activated sludge treated water coagulating sedimentation apparatus).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Activated sludge processing system 2 ... Precipitation separation state measuring device 2a ... Sampling device unit 2b ... Measuring unit 2c ... Data processing unit 3 ... Blower 4 ... Air diffuser pipe 5 ... Precipitation tank 6a ... Raw water pump 6b ... Return sludge pump 6c ... Excess sludge extraction pump 7 ... Aeration tank 8 ... Computer 10 ... Sampling tube 11・ ・ ・ Weight 12 ・ ・ ・ Lifting rope 13 ・ ・ ・ Winding device 14 ・ ・ ・ Suction pump 15 ・ ・ ・ Measurement channel 17 ・ ・ ・ Sludge densitometer

It is a figure which shows the flow of a standard activated sludge processing apparatus. It is a figure which shows the flow of the example of a measuring device of this invention. It is a figure showing the state of the sludge density | concentration when there is no bubble generation | occurrence | production in the vertical direction in a sedimentation tank. It is a figure showing the state of the sludge density | concentration when there exists bubble generation | occurrence | production in the vertical direction in a sedimentation tank. It is a model showing the sedimentation state of sludge when there is a little bubble generation in the vertical direction in the sedimentation tank. It is a model diagram showing the sedimentation state of sludge when there is considerable bubble generation in the vertical direction in the sedimentation tank. It is a model drawing showing the sedimentation state of sludge when the bubble generation of the vertical direction in a sedimentation tank is large. It is a model drawing showing the sedimentation state of sludge when sludge floats up by the bubble of the vertical direction in a sedimentation tank. It is a figure showing the change of the disturbance state of the sludge phase by passage of a sludge scraping member. It is a figure showing the top view inside a sedimentation tank. It is a figure showing the variation of the dispersion | variation in the sludge density | concentration of the sludge phase of the vertical direction in a sedimentation tank by passage of a sludge scraping member. It is a figure showing the sludge density | concentration change by passage of the sludge scraping member in a fixed position. It is a figure which shows the movement of the front-end | tip position of a sampling tube.

Claims (3)

In a water treatment system that separates turbidity or suspended solids in wastewater by gravity precipitation,
Measure the sludge concentration at multiple vertical positions in the settling tank at the timing linked to the movement of the sludge collector.
When the deviation value of the sludge concentration distribution below the sludge interface or the time change rate of the deviation value exceeds a predetermined threshold value for each, it is determined that the sedimentation is abnormal.
A method for measuring the precipitation state. In addition to the conditions of claim 1,
In accordance with the measurement of the sludge concentration, measure the pH value in the supernatant liquid phase and the sludge phase,
When the relative comparison value of the pH value of both or the temporal change rate of the pH value exceeds a predetermined threshold value for each, it is determined that there is a sedimentation abnormality.
A method for measuring the precipitation state. In addition to the conditions of claim 1,
In accordance with the measurement of the sludge concentration, the nitrate ion concentration in the supernatant liquid phase and the sludge phase is measured,
When the relative comparison value of the nitrate ion concentration or the temporal change rate of the nitrate ion concentration of both exceeds a predetermined threshold value for each, it is determined as sedimentation abnormality.
A method for measuring the precipitation state.

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