KR820000960B1 - Apparatus for detecting coagulation effect - Google Patents

Abstract

A coagulation effect detector suitable for controlling the purification process of a filtration plant was devised. Some suspended inorg. corpuscles in water were precipitated as flock with chemical coagulants and isolated from the settling bed. The fine flocks remaining in upper clean water were introduced to filter bed and filtrated. The water turbidity at the inlet of the settling bed is calculated and necessary quantities of coagulant for purifying can be controlled by this detector.

Description

Coagulation Effect Detection Device (凝集 效果 檢出 裝置)

Figure 1 shows the relationship between flocculation rate and loss head rise rate.

2 is related to the rate of head loss rise and supernatant turbidity.

3 and 4 show the relationship between filtration time and loss head rise rate when the coagulant injection rate is changed at different filtration rates.

5 is the relationship between the filtration time and the rate of head rise when raw water turbidity changes.

6 is a block diagram of a water purification process of a water purification plant in which the coagulation effect detection apparatus of the present invention is installed.

Figure 7 is a block diagram showing an embodiment of the aggregation effect detection apparatus of the present invention.

8 is a calculation flowchart of the aggregation effect detecting apparatus of the present invention.

9 is a waveform diagram on which the calculation of FIG. 8 is based.

The present invention relates to a coagulation effect detector suitable for control of a purification process such as a water purification plant.

In a water treatment plant, various water treatment operations are performed in order to improve the water quality of raw water taken from rivers and the like to make water suitable for the purpose of use.

(FIG. 1) For example, soluble iron, manganese, and the like in raw water are subjected to chlorine injection (chlorine treatment), oxidized to insoluble iron and manganese, and then precipitated and removed. Fine particles such as fine particles and clays of less than mm are flocculated and precipitated by injection of a flocculant, and organic sulphide such as frankton and various microorganisms are sterilized by the chlorine treatment and flocculation and flocculation by injection of flocculant as suspended particles. Remove

In addition, in order to improve the activity of aggregates by adjusting the pH and alkalinity of raw water, an alkali injection operation is performed.

In this way, chemical injection operations such as chlorine, flocculant and alkali are performed.

The flocculant is injected into the chlorine-treated and alkali-infused water in the chemical mixing paper, and mixed and exchanged to aggregate the turbidity in the water to form fine flock.

In other words, the sucrose is mainly hydrophobic colloidal particles, and is often charged in the negative side. To agglomerate the hydrophobic colloidal particles to make a floc, the absorption force between the particles is larger than the repulsive force. In the state, the repulsive force is large between the negatively charged colloidal particles having the same charge, and the particles fall only by approaching the particles due to the brown motion or the change of the flow caused by the microcirculation. The coagulant is a cationic agent that lowers the surface potential of the secondary charged colloidal particles, and itself acts as an antistatic colloid to coagulate with the secondary charged colloidal particles to form a fused fructus.

This fine fructose is suspended in water and enters the floc forming land, where it grows into a large fructose, after which the grown floc is sedimented and separated from the sedimentation basin. The supernatant of the sedimentation basin is then introduced into the filter, and the microfructs not sedimented at the sedimentation basin are filtered out here. The filtered water is drained to each end of the water through a purified water and a drainage basin.

In the water purification process of the water purification plant, the coagulation sedimentation treatment of the fine particles by the coagulant and the filtration treatment in the filter paper play an important role, but the coagulation sedimentation treatment is more important.

In the flocculation sedimentation treatment, the injection rate of the flocculant is generally determined by empirical values from measured values of raw turbidity, pH and alkalinity.

However, even if the turbidity, pH, and alkalinity of the raw water are the same, for example, the water quality is completely different in the cheoncheon city and the rainy day. In rainfall, even the same turbidity causes a difference in the particle size of the turbidity. Therefore, even if the injection rate of the flocculant is determined according to the measurement results of the raw water quality of turbidity, pH and alkalinity, if the water quality is changed, it is higher or lower than the appropriate injection rate of the flocculant.

As a result, even if the injection rate of the flocculant is higher or lower than the appropriate value, the repulsive force between the solutes becomes stronger than the suction force, so that the action of forming the fruc is lowered. In this case, large precipitates having good sedimentability are not formed and fine particles which do not settle in the sedimentation basin are increased.

Inevitably, the fine particles have to be filtered in the filter paper, so that the load on the filter paper becomes high, which causes inconvenience of the filter yarn. As a result, the number of backwash times of the filtered sand increases.

Therefore, it is necessary to determine the flocculation effect early after injecting a flocculant.

This determination result is to estimate the turbidity of the sediment water at the outlet of the sedimentation basin and to determine whether the injection rate of the flocculant is maintained at an appropriate value.

In other words, chemical injection control in water treatment of water purification plants is important for obtaining tap water by converting raw water into safe and stable water quality. Therefore, it has become common to introduce a calculator to drug injection control to be effective.

Therefore, it is necessary to detect the flocculation effect early and to control the injection rate of the flocculant to an appropriate value in order to obtain a good condensation effect in the calculation control of the chemical injection in the water purification plant. The appropriateness of the flocculation effect correlates with the size of the floc and a method of inferring the size of the fruc is known by performing turbidity at the outlet of the sedimentation basin, for example, as described in Japanese Patent Laid-Open No. 5-93160.

This method is equivalently judged when large turbidity is formed when turbidity is low and only small fructus is formed when turbidity is high according to the measurement result of turbidity at sediment outlet.

However, there is a delay by the residence time (4-5 hours) of the various places until the turbidity at the outlet of the settling basin is determined by injecting the flocculant.

Therefore, even if the treatment fails and the turbidity increases, the feed-back control for optimally correcting the injection rate of the flocculant according to the turbidity is difficult, and as a result, the load on the filter paper becomes large.

As another method for determining the coagulation effect, an industrial television is installed in the sedimentation resin to visually determine the size of the fructose.

However, since the pollution of the television is so severe, it must be repaired frequently, and water purification disorders requiring sexualization are inadequate.

The present inventors have studied in detail the method of early detection of the flocculation effect of the fructus under such a background. It was found that the effect of flocculation could be detected by monitoring the change in head loss rate.

When indicating that the detection result is inappropriate, the chemical feed rate is optimized by feeding back to the chemical mixing control system. Hereinafter, the experimental example which forms the basis of this invention is described by drawing.

Experimental Example

A 7 cm inner diameter and 2 m high filter cylinder were used to fill a glass beads (average particle diameter: 0.5 mm) to a depth of 95 cm as a filter agent. Sudden suspension of gaolin as raw water in raw water as a raw water, and a steady state experiment in which polyaluminum chloride (PAC) was gradually changed from an inappropriate value to an appropriate value as a flocculant, and a transient state of raw water turbidity or PAC injection rate was changed. Was conducted under the following conditions. Manometa were attached to the sides of the filter barrel at intervals of 5 cm.

When the tap water was filtered at a predetermined filtration rate prior to the experiment and the loss head inherent in the filter medium, water containing fructose formed by injecting a flocculant into the raw water mixed with the stinger to form a filament was flowed at a rate of 3 l / min from the top of the filter tank. As a result of the change in filtration power, the head loss rate was measured based on PAC injection rate and filtration time, respectively. The relationship between the rate of head rise and the symbol turbidity and the filtration rate were obtained. In addition, the trend of the loss head rise rate according to the position in the filter vessel was also obtained. Inappropriate values and titration values of the flocculant injection rate were determined by the Jar-Test.

When water containing a fruccope infiltrated the filter medium, it measured for 30 minutes at intervals of 3 minutes with a filtration time of 0 minutes.

The supernatant turbidity was measured 30 minutes after the start of the filtration, a portion of the fructose introduced into the filter was collected in a beaker and the supernatant solution after standing for 20 minutes.

It was found that the coagulant injection rate and the head loss rate were correlated in FIG. In other words, the increase rate increased as the injection rate of the flocculant increased. This results in poor flocculation effect at the injection rate of inadequate flocculation, formation of many small fructs, and detaining near the bottom of the surface of the filtration layer, and in the proper range of flocculant injection rate without affecting the loss head rise rate. The flock becomes large and detained at the surface of the filter so that the loss head rises. It was found that the supernatant and the rate of loss head rise were in the correlation shown in FIG. As the rate of ascent increases, the supernatant turbidity decreases.

In the case of a large flock, the settling speed increases, so the loss head rises.

At this time, it is thought that the symbol turbidity is lowered.

The raw water turbidity was maintained at 50 ppm, and 10 minutes after the start of the experiment, when the proper coagulant injection rate was changed from 6 ppm to inappropriate injection rate 0.4 ppm and the transient state was changed from 0.4 ppm to 6 ppm injection rate. The temporal change of the loss head rise rate is shown in FIG. 3 as the former curve A and the latter curve B. FIG.

When the injection rate was changed from the proper injection rate, the rate of loss head elevation decreased after about 8 minutes by changing the injection rate. This is because the large fructus held in the filter layer at the proper injection rate is detained in the form of the small fructus after the injection rate change, and the increase in the amount of detained fructs is slowed down. It is thought that a part of is peeled off and the small fructose is replaced with a large fructose, so that the loss head rise speed becomes small.

When the inadequate injection rate was changed to the proper injection rate, the loss head rise rate began to increase at 8 minutes after the change.

This is because the small fruct produced at the improper injection rate is detained in the lower part of the filter medium, so the rising speed is small.

Next, in Fig. 4, the filtration speed is set to 375 m / d, and the other conditions show the change over time of the loss head rising speed in the same case as in Fig. 3.

Ascending speed was changed at about 5 minutes after the flocculant injection rate was changed, and the filtration speed was shorter in response time than in the case of 187 m / d.

This is thought to be due to the increase of the filtration speed and the shortening of the transport time from the inlet of the filter to the filter medium layer.

FIG. 5 shows the change over time of loss head rise rate when the raw turbidity is increased to 50 ppm after 10 minutes from the start of filtration at a raw water turbidity of 10 ppm and an appropriate injection rate of 2 ppm. This case also shows the same tendency as the curves A and A 'of FIGS. 3 and 4, and indicates that the detection can be performed even when the raw turbidity increases and the coagulation effect becomes inadequate.

The present invention has been completed based on the results of the above examples, and solves the determination of the known art.

An object of the present invention is to monitor the change in the rate of loss head rise in the filter tube to detect the floc flocculation effect early, and when the detection result is inadequate, a warning signal is issued to optimize the drug injection rate with the purification process chemical injection control system. It is to provide a coagulation effect detection device.

According to the present invention, after the flocculant injection mixing, a part of the water having the proc is extracted and introduced into the filter tube of the present invention, and the head of the filter medium at the predetermined position of the filter media layer is detected at regular intervals to detect the lost head. Introduced in the calculation device, the rising head loss rate is calculated to detect the floc aggregation effect from the change of the rising rate.

The present invention can be used not only for detecting the flocculation effect but also for estimating the turbidity of the sedimentation outlet and the setting of the vane time of the sedimentation basin as described above.

Other objects and features of the present invention will become apparent from the following description.

In FIG. 6, 1 is an impingement well, and raw water taken with a pump (not shown) in a river etc. is introduce | transduced through the channel 2 in this impingement well.

In the impingement well 1, the chlorine of a control amount is injected into raw water by the computer controller CC from the chlorine tank 3. As a result, chlorine causes sterilization and oxidation of iron and manganese. The raw water after exiting the impregnation well (1) is injected with a control amount of alkali to adjust the pH and the alkalinity of the raw water.

That is, alkali, such as ready-made soda, from the alkali tank 6 injects control amount by a computer control system CC to raw water.

In the chemical mixing paper 7, a coagulant of a control amount by the computer control system CC is injected in response to the quality of raw water introduced, and is rapidly stirred by the stirrer 8.

A flocculant such as a lactate band or PAC (aluminum polychloride) is injected into the raw water from the tank 10. The flocculant is injected and rapidly stirred, and the suspended matter (particulates) contained in the raw water aggregates to form fine flock.

In the floc forming paper 11, slow stirring is performed, and fine flock is grown to become a large flock.

12 is an stirrer provided in the flock forming paper 11.

Water flowing out of the floc forming region 11 is then introduced into the settling basin 13, where the floc is sedimented off.

The supernatant of the settling basin 13 is introduced into the filter sheet 14. And the microparticles which did not settle out in the sedimentation basin 13 are removed here. The water exiting the filter paper 14 is not shown in the following, but is drained to each demand stage by a pump through a clarifier and a drain.

15 is a turbidimeter, 16 is pH, 17 is an alkalinity meter, the quality of raw water is measured, 18 is a flow meter, and a flow rate is measured.

A chemical injection rate such as a flocculant is calculated according to the computer control system CC and the measurement results of the above water quality and flow rate to control the chemical injection amount.

In such a purification process of the water purification plant, the coagulation effect detection device 19 is provided on the outlet side D of the flock forming paper 11.

An agglomeration effect detection device 19 is connected to the outlet side of the floc forming paper 11 via a water pipe 20. The sampling pump 21 is arranged in the water pipe 20.

As the pump 21, the water from the outlet is sampled into the floc forming paper 11, and the raw water is introduced into the coagulation effect detecting device 19. In addition, although the raw water is introduced into the coagulation effect detection device 19 by the sampling pump 21 in this embodiment, the pump 21 is not necessarily required.

For example, if the coagulation effect detection device 19 is provided below the protop formation paper 11 and the gravity type of dropping the sampled water is used, water can be introduced into the coagulation effect detection device 19.

As shown in FIG. 7, the coagulation effect detection device 19 detects an input at a specific position in the filtration section and a filtration section for filtering the introduced water. According to the signal, it is configured as a calculating device which introduces other necessary auxiliary signals and performs arithmetic processing.

The filtration part is composed of a cylindrical filter cylinder 24 and a packed bed G of the filter agent 25 filled in the filter cylinder 24. The upper part of the filter container 24 is open | released, and this opening part becomes the inflow port 26 of water supplied from the flock formation paper 11 side.

27 is a water collecting plate in which a plurality of holes are perforated, and this plate is provided in the lower part of the filter tube 24. In more detail, it arrange | positions through the packing (not shown) between the flange 28 provided in the lower part of the filter cylinder 24, and the flange 30 of the sump container 29 joined to this flange. A drain pipe 31 through which the filtered water is discharged communicates with the outlet side of the filtration unit, and an opening and closing side 32 is disposed in the drain pipe 31. In addition, the water supply pipe 33 communicates with the outlet side of the filtration unit separately from the drain pipe 31. 34 is an open / close side disposed in the water supply pipe 33. The open / close sides 32 of the open / close sides 32 and 34 are open during filtration. Meanwhile, the other opening and closing edge 34 is closed at this time.

In the case of backwashing, ie, filling between the particles of the filling layer G is filled, the open / close side 32 of the open / close sides 32 and 34 is closed.

On the other hand, the opening / closing edge 34 is opened, and the washing water is supplied to the outlet side of the filtration tank 22 as a feed water pump 35 for backwashing. Opening and closing operations of the opening and closing sides 32 and 34 are performed manually or automatically. In case of automatic operation, the opening and closing operation is performed in accordance with a preset timer (not shown) command.

During backwashing, the cleaning time depends on the capacity of the filling layer G, but only about 10 minutes. In addition, backwashing is performed before the pressure in the filling layer G becomes high, and proper filtration becomes difficult. The number of times is about once every 24 hours, and the frequency of backwashing changes as needed.

36 is an overflow pipe, and the inlet of this pipe is located at the top of the filter tube 24. On the other hand, the outlet of the pipe 36 communicated with the drain pipe 31 on the outlet side of the open / close side 32.

The pressure detection stage 23 for measuring the pressure in the stratified layer G is configured to detect the pressure in the surface layer portion C of the stratified layer G.

This makes it suitable for early and accurate detection of pressure changes during filtration.

The pressure detecting stage 23 introduces the pressure of the packed bed at regular intervals and the detection pressure signal P ₁ into the process extrusion force device PI / O of the calculating device.

That is, the calculation device controls the PI / O which introduces or outputs an input / output in a predetermined form as shown in Fig. 7, the central processing unit CPU which performs arithmetic processing, the storage device ME which stores data, and the CPU. CE is used as a unit.

In the PI / O, in addition to the detection pressure P ₀ , the reference pressure P ₂ , the flow rate signal Q detected by the flow rate detector 41 in the drain pipe 31 (the Q is used to correct the alarm measurement reference value) and backwashing In the water supply pipe 33, a backwash operation transmitting end 43 is provided, and a signal lamp from a signal line 44 instructing the backwash operation connected thereto is introduced. When these inputs are introduced into the CPU, the calculation device is an example. The computational control is performed according to the calculation flow chart of FIG. Is sent to (CC).

를 구하여 손실수두 상승속도의 변화는 제9도의 파형도를 기초로 하여 계산하여 응집효과를 검출한다는 예를 나타내고 있다.8 shows the difference of the differences from the i-th and i--1th data by introducing P ₁ and P ₂ into the calculation device at regular intervals.

The change in the loss head rise rate is calculated based on the waveform diagram of FIG.

는 미리 테이블로서 입력되어 있다.In this case, the storage unit

Is previously input as a table.

The waveform diagram of FIG. 9 was created according to FIG. 3 curve A of the said experiment example.

로 된다.If the input detection stage 23 is the atmospheric pressure when the reference pressure P ₂ is the atmospheric pressure in the manometer mechanism, the differential pressure is input.

It becomes

7 and 8, the flow rate Q is a correction signal for increasing the loss head rise rate by increasing the filtration speed, i.e., increasing the flow rate Q, as described with reference to FIG.

Next, a method for detecting the flocculation effect by the flocculation effect detecting apparatus of the present invention will be described.

First, as shown in FIG. 6, a series of chemical injections are performed, and the water exiting the floc forming paper 11 is sampled and continuously introduced into the coagulation effect detection apparatus 19 of the present invention through a water pipe. This water containing flock passes through the filter medium 25 filled in the keg 24 while descending the inside of the keg 24 as shown in FIG.

As a result, the flock present in the raw water is captured (filtered) by the filter medium 25. The filtered water is then discharged from the drain pipe 31 communicated with the lower part of the filter cylinder 24.

In this way, when the raw water is being filtered, the pressure detecting stage 23 periodically detects the pressure P ₁ during filtration.

The pressure detection stage 23 detects the pressure P ₁ during filtration as described above. As described above, the rate of change of the pressure P ₁ during filtration is correlated with the floc flocculation effect, i.e., the size of the floc, and the larger the rate of change, the larger the particle size of the floc.

If a chemical such as a flocculant is mixed into the raw water by an appropriate amount and the growth of the floc proceeds satisfactorily, the grain size of the formed floc is large and a good floc is formed. The large flock is mainly trapped in the surface layer portion C of the filter medium 25, and it takes time to reach the inside.

On the other hand, the small flock is also trapped in the surface layer portion C of the filter agent 25, but penetrates the surface layer portion C and is mainly captured in the lower layer portion of the filter layer G. As described above, the pressure is measured at the surface layer portion C. When the pressure change rate is large, the prog is large and the pressure change rate is small.

The pressure P measured as the pressure detecting stage 23 is introduced into the calculation device shown in FIG. 7, and the coagulation effect is detected by the stretching treatment as described above. When the detected value is an inappropriate injection rate, the medicine of FIG. It is fed back to the injection computer control system and operated at an appropriate injection rate.

In this way, the coagulation effect is detected, but when the filtration time elapses and the gap between the particles of the filter medium 25 fills up, it is necessary to backwash to remove and remove the prog trapped in the filter medium 25.

In this case, introduction of the sample name water into the filtration unit is stopped and the opening / closing edge 32 disposed in the drain pipe 31 is closed.

On the other hand, the opening and closing edge 34 disposed in the water supply pipe 33 is opened. At the same time, the feed water pump 35 is operated to feed the washing water into the filtration tube 24 via the feed pipe 33. The prog trapped by the filter medium 25 with this washing water is washed away and discharged from the upper portion of the filter cylinder 24 like the washing water through the overflow pipe as indicated by the arrow line in FIG. 8.

In this case, since the filter medium 25 has a specific gravity, it is not discharged together with the washing water.

After the backwash ends, the operation of the water supply pump 35 is stopped, and the open / close valve 34 is closed and the open / close valve 32 is opened.

After the predetermined operation is completed, the raw water is again introduced into the filtration unit and the proclumping effect is detected.

As described above, the coagulation effect detection apparatus of the present invention detects with high accuracy as the loss gain rising speed is large. Therefore, it is advantageous to increase the filtration rate as shown in FIG. Therefore, when the suction pump 40 is disposed on the outlet side of the filtration unit as a means for increasing the filtration rate, and the filtered water is sucked by the pump 40, the differential pressure P becomes larger than that of the gravity equation.

That is, by increasing the range of the differential pressure P that can be measured, it is possible to monitor the rising speed of the loss head with good accuracy. As described above, the present invention introduces a part of the raw water flowing into the sedimentation basin into the filter barrel, and detects the flocculation effect early by the rate of change of the filtration pressure to effectively mix the drug.

In the above-described embodiment, the detection is stopped at the time of washing, but if two identical ones are prepared and switched, it can be detected continuously.

Claims (1)

A flocculation effect detection device for a water treatment device in which a drug is injected into raw water to form a haze floc in raw water, and the floc is sedimented and separated from the sedimentation basin to purify the raw water. A filtering unit having a pressure detecting stage at a specific position of the filter, means for allowing a part of the water before entering the electric settling basin to be introduced from the filtering portion and discharged to the other end, and a means for monitoring the pressure change of the pressure detecting stage. Device.

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