JP4244769B2 - Aggregation apparatus and aggregation method - Google Patents

Description

  The present invention is a treatment of natural water as a raw material or a wastewater treatment for treating industrial wastewater or sewage, etc., by adding a flocculant to the raw water and stirring, thereby suspending suspended solids, colloidal components and organic in the raw water. The present invention relates to a coagulation apparatus and a coagulation method for coagulating and coarsening a substance, and in particular, by controlling the agitation strength and the amount of coagulant added in this coagulation process, it is possible to prevent coagulation inhibition and excessive or insufficient coagulant to be stable and efficient. The present invention relates to an aggregating apparatus and an aggregating method for performing an aggregating process.

  In water treatment using natural water as raw material and wastewater treatment for treating industrial wastewater or sewage, a flocculant is added to the raw water to condense and coarsen suspended substances, colloidal components and organic substances in the raw water. After that, solid-liquid separation is performed by precipitation, flotation, filtration, membrane filtration or the like.

  The agglomeration treatment is for increasing the solid-liquid separation efficiency such as precipitation, flotation, filtration, membrane filtration and the like located in the latter stage, and as the aggregating agent, generally an inorganic aggregating agent such as aluminum salt or iron salt is used. In many cases, a polymer flocculant is used in combination as an agglomeration aid for further coarsening the particles coagulated with the inorganic flocculant.

  In order to improve the agglomeration efficiency in the agglomeration treatment, it is important to smoothly diffuse and move the added aggregating agent and aggregating auxiliary agent into the raw water to increase the frequency of contact and collision with the agglomeration object. For this reason, a coagulation tank (hereinafter sometimes referred to as “stirring tank”) provided with a stirring means is generally used, and the raw water added with the coagulant is coagulated with stirring. The agitation tank generally includes a rapid agitation tank for agitation for contacting and colliding the agglomeration object and the aggregating agent in the raw water, and a slow agitation agitation tank for agitation for coarsening aggregated or agglomerated particles. It is divided into. As the stirring means, those using a stirring blade and those having a structure for stirring the raw water by bypassing the water channel are generally used. Moreover, the method of stirring during piping transfer using a pump and a static mixer is also used, and there is also an example using this together with a stirring tank.

  However, the aggregation or coagulation action by inorganic flocculants is inhibited by humic substances present in raw water, natural organic substances such as intracellular and extracellular metabolites produced by algae, and synthetic chemicals such as surfactants. Or, the setting speed becomes slow or the aggregation is poor.

  Conventionally, optimization of pH has been performed as a method for preventing this aggregation inhibition, and automatic pH adjustment is performed by linking a pH meter and an addition pump of an acid or alkaline pH adjuster. Yes. However, stable aggregation treatment cannot be performed only by pH adjustment.

  In the past, the mechanism by which natural organic substances such as humic substances contained in natural water and wastewater and synthetic chemicals such as surfactants cause aggregation inhibition has not been fully elucidated, and identification of these inhibitors It has not been done. For this reason, in the treatment of irrigation water and wastewater, in order to set the optimum flocculation conditions, an operation of determining the addition concentration and pH of the flocculating agent using a separate jar tester is essential, but such operation is generally complicated. It takes a long time to operate, and therefore, it cannot cope with fluctuations in the quality of raw water, and the determined amount of flocculant added and pH adjustment value cannot be immediately reflected, resulting in poor aggregation. .

  For this reason, in the present situation, a method is adopted in which the flocculant addition amount is set in advance higher than the upper limit value of the expected required addition amount, and a method of preventing poor aggregation by excessive addition of the flocculant, Adding an excessive amount of the flocculant in this manner is not preferable because it not only increases the cost of the drug but also increases the amount of sludge generated.

  On the other hand, with respect to aggregation inhibitors such as natural organic substances and synthetic chemical substances, it is known that by increasing the contact and collision frequency with an inorganic flocculant, aggregation inhibition can be prevented and aggregation and condensation speed can be increased. However, it is not easy to set such conditions in an actual stirring tank.

  Japanese Examined Patent Publication No. 6-103296 proposes a test apparatus for automatically performing a jar test for setting optimum conditions in a combination of a flocculant addition rate to raw water, a stirring time, and a stirring speed. However, this apparatus is a jar tester and is not for performing the agglomeration treatment by reflecting the test result in an actual stirring tank.

Japanese Patent No. 3205450 discloses the measurement of the particle size of the aggregated floc in the stirring tank and the ultraviolet absorbance of the soluble organic substance, and controls the amount of the flocculant added based on these results. A chemical injection device that determines the number of rotations of a stirrer in a stirring tank from the diameter has been proposed. This device detects the concentration of soluble organic matter in the agitation tank, that is, the concentration of soluble organic matter in the coagulated liquid to which the coagulant is added and is stirred, and this is added together with the detected value of the particle size of the coagulation floc. On the other hand, the agitation strength is set based on the particle size of the agglomerated floc, but it cannot be said that a sufficiently satisfactory agglomeration result has been obtained, and further improvement is desired. It is rare.
Japanese Patent Publication No. 6-103296 Japanese Patent No. 3205450

  The present invention prevents agglomeration inhibition by an aggregating inhibitor in the raw water by accurately controlling the stirring strength and the aggregating agent addition amount in the agglomeration treatment, and prevents the use of a small amount of aggregating agent by preventing excess or deficiency of the aggregating agent. An object of the present invention is to provide an aggregating apparatus and an aggregating method that perform stable and efficient agglomeration treatment in an amount.

The flocculation apparatus of the present invention is a flocculation apparatus for performing a flocculation process by adding a flocculant to raw water and stirring, a flocculation tank into which raw water is introduced, a stirring means for stirring the liquid in the flocculation tank, and raw water Flocculant addition means for adding a flocculant, an inhibitor detection sensor for detecting the amount of the aggregation inhibitor in raw water, and stirring intensity control for controlling the stirring intensity of the stirring means based on the detection value of the inhibitor detection sensor Means, a coagulation state detection sensor for detecting the coagulation state in the coagulation tank, and a coagulant addition amount control means for controlling the coagulant addition amount of the coagulant addition means based on the detection value of the coagulation state detection sensor. Ri Na and wherein the inhibitor detection sensor is characterized by TOC analyzer, COD meter or absorptiometer der Rukoto.

Agglomeration process of the present invention, introduced into a flocculation tank provided with stirring means raw water, in the aggregation method for aggregating treatment by stirring by adding an aggregating agent, raw water aggregation inhibitor amount TOC meter, COD meter or Detecting with an absorptiometer , controlling the stirring intensity of the stirring means based on this detected value, detecting the agglomeration state in the coagulation tank, and controlling the amount of flocculant added to the raw water based on this detected value It is characterized by.

  In the present invention, the concentration of an inhibitory substance such as an organic substance in raw water that causes aggregation inhibition is detected, and the stirring intensity is controlled according to the tendency of aggregation inhibition of the raw water, thereby suppressing the aggregation inhibition by the inhibitory substance, and the flocculant It is possible to increase the aggregation effect due to In this case, since the stirring intensity can be controlled according to the degree of aggregation inhibition, excessive energy for stirring is not consumed. In addition, in such a condition that inhibits aggregation inhibition by controlling the agitation strength, the aggregation state is detected in real time, and the addition amount of the aggregating agent is controlled based on the detected value. A good agglomeration treatment can be performed with the minimum.

In the present invention, coagulation is not particularly limited as current state detection sensor, it is possible to use a light blocking type fine particle sensor or light scattering particle sensor or the like detects the clarity between the aggregated particles of cohesive tank solution.

  According to the flocculation apparatus and the flocculation method of the present invention, by properly controlling the stirring strength and the amount of the flocculant added in the flocculation treatment, the aggregation inhibition by the aggregation inhibitor in the raw water is prevented, and the excess and deficiency of the flocculant is also provided. Thus, stable and efficient flocculation treatment can be performed with a small amount of flocculating agent used.

  Embodiments of the aggregating apparatus and the aggregating method of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a system diagram showing an embodiment of a coagulation / sedimentation apparatus provided with the coagulation apparatus of the present invention, and FIG. 2 is a cross-sectional view of a stirring tank showing an example of stirring intensity control means.

  In FIG. 1, reference numeral 1 denotes a raw water tank, which includes an inhibitor detection sensor 11. Reference numeral 2 denotes a coagulation agitation tank, which includes an agitator 12 and an aggregation state detection sensor 13. 3 is a settling tank. Reference numeral 4 denotes a flocculant storage tank, which includes a chemical injection pump 14. Reference numeral 5 denotes a control device, to which the detection value of the inhibitor detection sensor 11 and the detection value of the aggregation state detection sensor 13 are input, and the stirring intensity control signal of the stirrer 12 and the rotation speed control signal of the medicinal pump 14 are output. The

  The raw water is introduced into the raw water tank 1, and the inhibitory substance detection sensor 11 detects the aggregation inhibitory substance concentration in the raw water, for example, the organic substance concentration, and the detection result is input to the control device 5. As this inhibitor detection sensor 11, in addition to a commercially available TOC meter and COD meter, an ultraviolet short wavelength UV meter near a wavelength of 260 nm, an ultraviolet to visible light region near a wavelength of 200 nm to 700 nm, and a wide range are scanned. A sensor or the like that can detect the absorbance of the light can be suitably used.

  The raw water in the raw water tank 1 is then introduced into the coagulation stirring tank 2. In the flocculation agitation tank 2, the raw water is subjected to the flocculation process by adding the flocculating agent in the flocculant storage tank 4 by the chemical injection pump 14 and stirring the raw water. The aggregation state in the aggregation stirring tank 2 is detected by the aggregation state detection sensor 13, and the detection result is input to the control device 5. The agglomeration state detection sensor 13 includes a device and a sensor for detecting the turbidity of a supernatant obtained by transferring the liquid in the agglomeration stirring tank 2 to another sedimentation tank and allowing it to settle for a certain period of time, or the zeta potential of aggregated or agglomerated particles. Although a device and a sensor for detecting the flow potential can also be used, a light blocking fine particle sensor or a light scattering fine particle sensor for detecting the clarity between particles condensed or aggregated in the aggregation stirring tank 2 is preferable. Used.

  The stirring intensity of the stirrer 12 in the aggregation stirring tank 2 is controlled based on the detection value of the inhibitor detection sensor 11. That is, for example, the control device 5 compares the input detection value of the inhibitor detection sensor 11 with a preset reference value, and if this detection value exceeds the reference value, the stirring intensity is increased and the reference value or less is increased. If so, control is performed to reduce the stirring intensity.

  In addition, control of the stirring intensity | strength of the aggregation stirring tank 2 is performed by controlling the rotation speed of the stirrer 12 with the rotation control apparatus 21 attached to the drive motor of the stirrer 12, as shown to Fig.2 (a). be able to. Further, as shown in FIG. 2 (b), a circulation line 23 having a circulation pump 22 and a stirring element 24 such as a static mixer are provided separately from the stirrer 12 and pumped and stirred after the liquid in the coagulation stirring tank 2 is stirred. It is also possible to control the stirring intensity by controlling the operation of the circulation pump 22 and / or the stirring element 24 so as to return after the liquid in the agglomeration stirring tank 2 is taken out and stirred. Moreover, stirring intensity can also be controlled using these together.

  The amount of the flocculant added to the aggregation stirring tank 2 is controlled based on the detection value of the aggregation state detection sensor 13. That is, for example, in the control device 5, the input detection value of the aggregation state detection sensor 13 is substituted into a preset determination formula for the amount of flocculant added, and the rotation speed of the medicinal pump 14 is controlled based on the calculation result. And an appropriate amount of flocculant is added. As this medicine injection pump 14, a commercially available variable metering pump or the like is used.

  The agglomerated water that has been agglomerated by adding and aggregating the aggregating agent in the agitation agitation tank 2 is introduced into the precipitation tank 3 to coagulate and aggregated particles are settled and separated, and the supernatant water is taken out as treated water. .

  1 and 2 show an example of an embodiment of the present invention, and the present invention is not limited to the one shown in the drawings as long as the gist thereof is not exceeded.

  Although the pH adjusting means is not described in FIGS. 1 and 2, the stirring tank 2 normally aggregates a pH sensor and an acid and / or alkaline pH adjusting agent based on the detected value of the pH sensor. An automatic pH adjusting means for adding to the raw water introduction pipe 2 to the stirring tank 2 or the coagulation stirring tank 2 is provided. In the present invention, the set pH value of the pH adjusting means is detected by an inhibitor detection sensor for raw water. The pH may be changed based on the value, whereby the inhibition of aggregation is more reliably suppressed, and a good aggregation treatment can be performed with a small amount of the flocculant added.

  In addition, a flow meter for measuring the amount of raw water is provided, and the stirring intensity may be controlled according to the amount of the aggregation-inhibiting substance in the raw water, and the stirring time may be controlled according to the increase or decrease in the amount of raw water. It is possible to reduce the stirring energy by suppressing an increase in unnecessary stirring energy.

  Furthermore, a means for measuring the water temperature of the raw water may be provided, and the water temperature of the raw water may be incorporated in the control of the stirring strength, thereby suppressing the aggregation inhibition based on the decrease in the water temperature by increasing the stirring strength, and the water temperature lowering The increase in the required amount of flocculant added due to can be suppressed.

  Further, in FIG. 1, the flocculant is added to the flocculent stirring tank 2, but the flocculant may be injected into the raw water introduction pipe to the flocculent stirring tank 2. Furthermore, although the precipitation tank 3 is shown in FIG. 1 as the solid-liquid separation means of the coagulated treated water, the present invention is not limited to the precipitation tank, but various solid-liquid separation means such as a flotation tank, a filtration apparatus, and a membrane filtration apparatus. It can be effectively applied as an aggregation means in the previous stage.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1
In an agglomeration / sedimentation / sand filtration facility using River A, where organic matter contamination is advanced, as the water source, the agglomeration / sedimentation treatment according to the present invention was performed using the agglomeration / precipitation apparatus shown in FIG. The agglomeration stirring tank used is a square rapid stirring tank with a paddle type stirrer (60 rpm, 5 kW) having an effective capacity of 300 m ³ , the amount of raw water is 30 m ³ / h, and the residence time of the rapid stirring tank is 6 minutes.

  Polyaluminum chloride (PAC) was used as the flocculant. Further, the pH of the rapid stirring tank was automatically adjusted by a pH adjusting means (not shown) so that the pH was 6.5.

  As the inhibitor detection sensor, an S :: CAN sensor (S :: CAN MESSTECHNIK GMBH (Austria), cell width 35 mm) capable of scanning an ultraviolet to visible light region having a wavelength of 200 nm to 700 nm is used.

The stirring speed of the rapid stirring tank is fixed, and as shown in FIG. 2 (b), the liquid in the stirring tank is pumped up and circulated through the pump (180 m ^{3 /} h, 8.7 kW). Was mixed with a static mixer (OHR line mixer MX-150 manufactured by Seika Sangyo Co., Ltd.).

  With regard to the UV spectrum of the raw water S :: CAN sensor, paying attention to the absorbance at 240 to 280 nm, the UV 240 nm absorbance is used as a representative value of the organic matter that causes aggregation inhibition, and when the UV 240 nm absorbance exceeds 0.1, When the circulation pump was driven and the UV 240 nm absorbance was 0.1 or less, the stirring intensity was controlled by ON / OFF control to stop the circulation pump.

  Further, as the aggregation state detection sensor in the agitation tank, a light scattering fine particle sensor (manufactured by Kurita Kogyo Co., Ltd., red light 635 nm) for detecting the clarity of the liquid between the aggregated or aggregated particles was used. Among the output waves of this sensor, the output value of the PAC chemical injection pump was proportionally controlled using the lower limit output value as a representative value.

Comparative Example 1
Only the ON / OFF control of the circulation pump by the S :: CAN sensor and automatic pH adjustment were performed, and the coagulation sedimentation treatment was performed in the same manner as in Example 1 except that the PAC addition concentration was set each time with a jar tester.

Comparative Example 2
The coagulation-precipitation treatment was performed in the same manner as in Example 1 except that only proportional control of the PAC injection pump with a light scattering fine particle sensor and automatic pH adjustment were performed, and the stirring intensity was fixed only to the paddle stirrer. It was.

Comparative Example 3
Only the pH was automatically adjusted, the PAC addition concentration was set with a jar tester each time, and the stirring strength was agglomerated and precipitated in the same manner as in Example 1 except that the paddle type stirrer was fixed.

  When the absorbance of raw water UV240nm is increased to 0.12 to 0.14, the coagulation sedimentation treatment is performed for one day each under the four conditions of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Table 1 summarizes the results of water flow.

  Table 1 shows the following.

  In Comparative Example 3, in order to keep the turbidity of the precipitation tank treated water at 0.1 degree, the PAC addition concentration needs to be 60 mg / L, and the total cost at this time was 1116 yen.

  In Comparative Example 2 in which the addition of the flocculant was controlled by the light scattering fine particle sensor, the PAC addition concentration could be reduced to 38 mg / L, but the turbidity of the precipitation tank treated water was 0.2 degree, and Comparative Example 3 A little higher than. The total cost at this time was 720 yen.

  Further, in Comparative Example 1 in which the circulation pump was operated by the S :: CAN sensor to control the stirring intensity, the PAC addition concentration was required to be 36 g / L in order to make the precipitation tank treatment water turbidity 0.1 degree. . The total cost at this time was 717 yen.

  On the other hand, in Example 1, the power for operating the circulation pump was required, but the PAC addition concentration could be reduced to 25 mg / L, and the total cost was 519 yen / h. Was reduced by about 53%. Moreover, the turbidity of the sedimentation tank treatment water could be kept at 0.1 degree.

  From the above results, according to the present invention, it is possible to effectively prevent the aggregation inhibition by the aggregation inhibitory substance by adjusting the stirring intensity, and by performing the appropriate dosing control of the aggregating agent based on the aggregation state, It can be seen that the required addition amount is reduced to reduce the drug cost, and thereby, treated water with good water quality can be stably obtained at low cost.

  INDUSTRIAL APPLICABILITY The present invention is effectively applied to raw water agglomeration treatment in various water treatments such as water treatment using natural water as a raw material and waste water treatment for treating industrial wastewater or sewage.

It is a systematic diagram which shows embodiment of the coagulation sedimentation apparatus provided with the coagulation apparatus of this invention. It is sectional drawing of the stirring tank which shows the example of a stirring intensity control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Aggregation stirring tank 3 Precipitation tank 4 Coagulant storage tank 5 Control apparatus 11 Inhibitor detection sensor 12 Agitation machine 13 Aggregation state detection sensor 14 Chemical injection pump 21 Rotation control apparatus 22 Circulation pump 23 Circulation line 24 Agitation element

Claims (3)

In the aggregating apparatus that agglomerates by adding a flocculant to the raw water and stirring,
A coagulation tank into which raw water is introduced;
Stirring means for stirring the liquid in the coagulation tank;
A flocculant addition means for adding the flocculant to the raw water;
An inhibitor detection sensor for detecting the amount of the aggregation inhibitor in the raw water;
Stirring intensity control means for controlling the stirring intensity of the stirring means based on the detection value of the inhibitor detection sensor;
An aggregation state detection sensor for detecting an aggregation state in the aggregation tank;
Ri Na and a coagulant addition amount control means for controlling the coagulant addition amount of the flocculant addition means based on the detected value of the aggregated state detection sensor, wherein the inhibitor substance detection sensor TOC meter, COD meter or absorbance Keidea Rukoto agglomeration apparatus according to claim. Oite to claim 1, agglomerator wherein said aggregated state detection sensor is a light shielding type fine particle sensor or light scattering particle sensor for detecting the clarity between the aggregated particles of said aggregate tank solution. In the flocculation method in which the raw water is introduced into a flocculation tank equipped with a stirring means, and the flocculation process is performed by adding and stirring the flocculating agent,
The amount of agglutination-inhibiting substance in the raw water is detected by a TOC meter, a COD meter, or an absorbance meter, and the stirring intensity of the stirring means is controlled based on this detected value.
A coagulation method characterized by detecting the coagulation state in the coagulation tank and controlling the amount of coagulant added to the raw water based on the detected value.

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