JP2020011207A - Flocculant injection controller - Google Patents

Abstract

To provide a flocculant injection controller capable of appropriately controlling each injection amount when injecting two or more kinds of flocculants.SOLUTION: A first flocculant is added to a first flocculation tank 3 by a first chemical injector 4. The detection signal of a first flocculation state monitoring sensor 5 is input into a controller 6 and the first chemical injector 4 is controlled. A second flocculant is added to a second flocculation tank 8 by a second chemical injector 9. The detection signal of a second flocculation state monitoring sensor 10 is input into the controller 6 and the second chemical injector 9 is controlled. Flocculation state monitoring sensors 5, 10 have light emission parts irradiating laser beams toward a flocculation treatment liquid and light receiving parts where a light receiving optical axis is in an orthogonal direction to the light emission optical axis of the light emission part and flocculation behaviors in the flocculation tanks are determined from change by time of scattered light intensity signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coagulant injection control device used when performing coagulation treatment of various industrial wastewater or industrial water, etc., in particular, after adding an inorganic coagulant to raw water, suitable for coagulation treatment to add an organic coagulant The present invention relates to a coagulant injection control device.

  When coagulation treatment is performed to remove turbidity, organic matter, and the like from various kinds of wastewater and water, an inorganic coagulant such as iron chloride or polyaluminum chloride may be used in combination with an organic coagulant. By using these two types of chemicals, the flocculation floc is coarsened and the subsequent solid-liquid separation operation is facilitated, and the amount of sludge generated can be reduced by suppressing the addition amount of the inorganic flocculant.

  It is necessary to add an appropriate amount of coagulant according to the quality of the water to be treated. If the amount of chemicals added (the amount injected) is insufficient, the removal of turbidity and organic substances contained in the water to be treated becomes insufficient, and the quality of the treated water deteriorates. On the other hand, if the added amount of the chemical is excessive, the chemical leaks to the subsequent stage, which may cause an increase in load and contamination in the subsequent processing.

  To determine the optimal amount of chemicals to be added, it is fundamental to perform a jar test.However, it takes time and effort to perform a jar test every time the water quality of the water to be treated fluctuates. , Cannot respond immediately to fluctuations and is not realistic.

  Patent Literatures 1 and 2 disclose that a laser beam is directed toward water, and the addition of a flocculant is controlled using a flocculation state monitoring sensor that measures the flocculation state by receiving scattered light scattered by flocs or the like in the water. It is described.

JP 2002-195947 A JP-A-2017-26438

  Conventionally, when coagulating with an inorganic coagulant and an organic coagulant, a large amount of the inorganic coagulant (polyaluminum chloride, etc.) injected in the first stage and the organic coagulant (polymer coagulant, etc.) injected in the subsequent stage is used. By controlling the amount of the inorganic coagulant that is injected into the container and greatly affects the amount of cake generated, the effect obtained finally is maximized. Since the injection amount of the organic coagulant is very small compared to the injection amount of the inorganic coagulant, a necessary and sufficient amount is injected in a fixed amount, and when the water quality of the raw water fluctuates, the injection amount of the organic coagulant is reduced. Often adjusted.

  When the components of waste water frequently change with the production of various varieties and small quantities as in the recent food manufacturing industry, the frequency of adjusting the injection amount of the organic coagulant increases.

  When controlling the coagulant injection amount using the coagulation state monitoring sensor, the coagulation state is monitored by the monitoring sensor after injecting the organic coagulant, and the injection amount of the inorganic coagulant is controlled based on the result. Have been done.

  In the drug injection control based on such an aggregation state monitoring sensor, a change in the aggregation state (SS concentration between flocs and intensity distribution of scattered light from the flocs) detected by the aggregation state monitoring sensor is caused by an inorganic flocculant and an organic flocculant. It is important to determine which injection amount is significantly affected by the injection amount. In order to make this determination, a method of periodically changing the amount of the inorganic coagulant injected and observing a change in the detected value of the coagulation state by the coagulation state monitoring sensor can be considered. However, in this method, is the change in the coagulation state that appears due to a change in the dosage of the inorganic coagulant, or is it an accidental change in the relationship between the dosage of the organic coagulant and the coagulation state? Is difficult to judge.

  Therefore, conventionally, an on-site manager periodically visually observes the floc state of the coagulation tank, and manually adjusts the inorganic coagulant injection amount while automatically adjusting the organic coagulant injection amount. The method has been taken. However, in this method, when the properties of the wastewater to be received fluctuate in a short period of time, the frequency of adjustment increases, and the burden on the site manager increases.

  An object of the present invention is to provide a coagulant injection control device capable of accurately controlling the amount of each coagulant when two or more coagulants are injected.

  A coagulant injection control device according to the present invention includes a first to n-th chemical injection devices provided in first to n-th (n is 2 or more) coagulation tanks, and a treatment of the first to n-th coagulation tanks. A first to an n-th aggregation state monitoring sensor provided so as to be capable of measuring a liquid, and a controller for controlling a drug injection amount of each injection device based on a detection result of each aggregation state monitoring sensor; The coagulation state monitoring sensor has an irradiation unit that irradiates laser light into water and a light receiving unit that receives scattered light, and the controller uses the time change of the scattered light intensity signal to detect a floc in the coagulation tank. Determine the state of formation.

  In one aspect of the present invention, the controller calculates a required medicine injection amount by a preset arithmetic expression.

  In one embodiment of the present invention, a first coagulation tank in which an inorganic coagulant is dispensed as the first coagulant, and a second coagulation tank in which a polymer coagulant is dispensed as the second coagulant And

  In the coagulant injection control device of the present invention, the coagulation state of each coagulation tank into which the coagulant is injected can be monitored, and the injection amount of each coagulant can be individually and accurately controlled.

It is a lineblock diagram of a coagulant injection control device concerning an embodiment.

  Hereinafter, the coagulant injection control device 1 according to the embodiment will be described with reference to FIG.

  In the coagulant injection control device 1, raw water, which is water to be treated, is introduced into the first coagulation tank 3 via the inflow pipe 2, and the first coagulant 4 adds the first coagulant. A first coagulation state monitoring sensor 5 is provided in the first coagulation tank 3, and a detection signal thereof is input to the controller 6. The controller 6 controls the first chemical infusion device 4 based on the detection signal.

  The liquid subjected to the coagulation treatment in the first coagulation tank 3 (first coagulation treatment liquid) is introduced into the second coagulation tank 8 via the advection pipe 7, and the second coagulant 9 adds the second coagulant. You. A second coagulation state monitoring sensor 10 is provided in the second coagulation tank 8, and a detection signal thereof is input to the controller 6. The controller 6 controls the second chemical infusion device 9 based on the detection signal.

  The liquid subjected to the coagulation treatment in the second coagulation tank 8 (second coagulation treatment liquid) is sent to the solid-liquid separation step via the outflow pipe 11.

  In this embodiment, an inorganic coagulant is suitable as the first coagulant, and an organic coagulant, particularly a polymer coagulant, particularly a cationic polymer coagulant is preferable as the second coagulant.

  Examples of the inorganic coagulant include iron-based inorganic coagulants such as ferric chloride, ferric sulfate, polyferric chloride, and ferric polysulfate, aluminum chloride, polyaluminum chloride, sulfate bands, aluminum hydroxide, and aluminum oxide. And aluminum-based inorganic flocculants.

  Examples of the cationic polymer coagulant include poly (diallyldimethylammonium chloride), poly (2-dimethylaminoethyl methacrylate), polydimethylaminoethyl methacrylate benzyl quaternary salt, polyethyleneimine, polyallylamine, polyvinylamine, poly ( 2-dimethylaminoethyl methacrylate), poly (2-vinyl-1-methylpyridinium), dialkylamine-epichlorohydrin polycondensate, polylysine, chitosan, diethylaminoethyldextran and the like.

  The coagulation state monitoring sensors 5 and 10 are preferably, as in Patent Documents 1 and 2, a light emitting unit that irradiates a laser beam toward the coagulation treatment liquid, and a light receiving optical axis in a direction orthogonal to the light emitting optical axis of the light emitting unit. And a light receiving unit. In addition, a light emitting circuit, a detection circuit, and a measurement circuit are provided for performing an issuance operation of the light emitting unit and analysis of a light receiving signal of the light receiving unit. The measurement circuit includes a timing circuit, an A / D conversion unit, a calculation unit, and the like.

  As in Patent Documents 1 and 2, the laser light emitted from the light emitting section to the measurement area is scattered by the particles in the measurement area, the scattered light is received by the light receiving section, and the light is aggregated based on the temporal change of the received light intensity. The state is measured.

  The light emitting circuit sends an electric signal having a constant modulation frequency to the light emitting unit in response to a signal from the timing circuit, and causes the light emitting unit to emit laser light. The light emitting section emits a laser beam according to a signal from the light emitting circuit. The light receiving unit receives the scattered light generated when the laser light hits the suspended matter in the water, and converts the scattered light into an electric signal. The detection circuit removes a modulation component from the electric signal from the light receiving unit and outputs a light receiving voltage according to the scattered light intensity.

  The measuring circuit transmits a signal for light emission (a specific frequency modulated wave) to the light emitting circuit, converts a signal from the detection circuit into a digital signal, performs a logical operation, and outputs information on aggregation.

  As the agglutination state monitoring sensor, monitoring devices described in Patent Documents 1 and 2, in particular, monitoring devices described in Patent Nos. 4605327 and 6281534 to which the patents are applied can be suitably used. However, the present invention is not limited to this.

In addition, the coagulation monitoring device of Patent No. 4605327
An agglutination monitoring device that monitors a state of a suspension in a fluid to be measured to be subjected to agglutination, separately from the agglutinate,
A laser light irradiating unit for irradiating the laser light modulated at a predetermined frequency into the fluid to be measured,
A scattered light receiving unit that receives scattered light scattered by particles in the fluid to be measured in the irradiation region of the laser light,
A photoelectric conversion circuit that converts the scattered light received by the scattered light receiving unit into an electric signal;
A detection circuit for performing AM detection on the electric signal converted by the photoelectric conversion circuit at the predetermined frequency and extracting a scattered light component due to the laser light;
When the signal after detection by the detection circuit has a peak fluctuation, the signal intensity of the lowest value of the signal after the detection as the intensity of scattered light scattered by unagglomerated suspensions in the fluid to be measured, With a minimum value detection circuit to detect and distinguish from scattered light due to aggregates in the fluid to be measured,
An agglutination monitoring device, wherein a change in the minimum value of the signal intensity is detected as a change in the number of unagglomerated colloid particles in the fluid to be measured. "
It is.

The coagulation monitoring device of Japanese Patent No. 6281534 is
A coagulation monitoring device for monitoring the treatment state of the water to be coagulated,
A measurement light irradiator that irradiates the measurement region with the measurement light of the water to be treated,
A scattered light receiving unit that receives scattered light due to the particles of the water to be treated in the measurement region,
An amplitude measuring means for measuring an amplitude of a received light signal obtained by the scattered light receiving unit, monitoring and counting the appearance of the measured amplitude, calculating an occurrence rate or occurrence frequency of a specific amplitude, and A measurement value calculating unit that calculates an index related to the aggregation of the water to be treated, which represents the particle size of the floc in the treated water,
With
The amplitude measuring means detects a first inflection point where the light receiving signal changes from rising to falling and a second inflection point changing from falling to rising, and detects the first inflection point and the second inflection point. An agglutination monitoring device, wherein the amplitude is measured from a level difference at an inflection point. "
It is.

  In one embodiment of the present invention, in the embodiment of FIG. 1, an inorganic coagulant is used as the first coagulant, a polymer coagulant is used as the second coagulant, and the above-mentioned Patent Document 1 or 2 is used as the coagulation state monitoring sensor Use

  In this case, the particle size distribution of fine flocs generated at the time of coagulation by the inorganic coagulant in the first coagulation tank 3 is measured by the particle size measurement function of the coagulation state monitoring sensor 5, and the polymer coagulation in the second coagulation tank 8 is performed. The turbidity between flocs, which can be measured by floc growth by the agent, is measured by the turbidity measuring function of the coagulation state monitoring sensor 10. Alternatively, or additionally, the first and second coagulation state monitoring sensors are provided with a function of measuring the particle size distribution of the formed floc, so that the injection amounts of the first and second coagulants are individually optimized. Let it. However, since the transition of the optimal medicine dosing point may occur due to the combination in the relation between the amounts of the polymer flocculant and the inorganic flocculant, the controller 6 incorporates an adjustment method in advance, so that Realizes stable coagulation control close to or more than the state of visual management.

  For example, the amount of the inorganic coagulant injected into the first coagulation tank 3 is determined based on the particle size distribution information or the inter-floc turbidity information obtained from the coagulation state monitoring sensor 5, and And controlling the amount of the polymer coagulant injected into the second coagulation tank 8 based on the particle size distribution information or the inter-floc turbidity information obtained from the coagulation state monitoring sensor 10. Control the dose of medicine. In addition, while confirming whether or not the amount of the medicine injected by the first injection device 4 at this time does not exceed the upper limit or the lower limit of the injection amount of the injection device 4 at the current injection amount of the injection device 9, When the value is out of the range between the lower limit and the upper limit, the value is set within the range from the lower limit to the upper limit of the dosing device 4 or the current dosing amount of the second dosing device 9 is changed to the first dosing device 4. The control device 6 has a function of changing the injection amount of the injection device 9 to the injection amount that can be changed to the new injection amount (however, the lower limit to the upper limit).

  In addition, while confirming whether or not the amount of the injection by the second injection device 9 exceeds the upper limit or the lower limit of the injection amount of the injection device 9 at the current injection amount of the injection device 4, the lower limit or the upper limit is checked. If it is out of the range, the value is set within the range from the lower limit to the upper limit of the chemical dosing device 9 or the current chemical dosing amount of the first chemical dosing device 4 is set to a new value. The control device 6 has a function of changing the injection amount of the injection device 4 to the injection amount that can be changed to the injection amount (however, the lower limit to the upper limit).

  In the coagulant injection control device 1 of FIG. 1, in the coagulation good state in which the coagulant is injected by the chemical dosing devices 4 and 9 so that a sufficient coagulation effect can be obtained in the coagulation tanks 3 and 8, respectively. In the case where the raw water inflow amount or the raw water composition / properties suddenly change, the coagulation state of the first coagulation tank 3 is deteriorated unless the injection amount of the first coagulant is changed to an appropriate value.

  When the injection amount of the first flocculant (inorganic flocculant) is insufficient, the first flocculation tank 3 has a delay in floc formation speed or insufficient floc growth. This phenomenon is observed in the form of a decrease in the occurrence ratio of the scattered light intensity that is equal to or more than a certain value in the scattered light intensity in the aggregation state monitoring sensor 5. Conversely, when the amount of injected inorganic coagulant is excessive, if the growth of floc is promoted, the appearance ratio of larger scattered light will increase, and if the growth state is sufficient, the overall It appears as an increase in the appearance ratio.

  When the injection amount of the polymer flocculant in the second flocculation tank 8 becomes insufficient, the crosslinking effect is weakened, so that sufficient floc growth cannot be obtained, and the scattered light intensity detected by the flocculation state monitoring sensor 10 , The appearance ratio of the scattered light intensity equal to or higher than a certain value decreases. On the other hand, if the injection amount of the polymer coagulant is excessive, the appearance ratio of relatively small scattered light intensity in the scattered light intensity detected by the aggregation state monitoring sensor 10 decreases. In addition, when the amount of the polymer flocculant is insufficient, the amount of the SS in the liquid (the amount of the suspension that cannot completely become a floc) increases, so that the scattered light intensity not depending on the floc except for the scattered light from the floc is increased. The minimum value of (turbidity between flocs) increases. Even from such a rise in the minimum value, it is possible to detect a state where the amount of the polymer coagulant is insufficient.

  When a change occurs in the detection signal of the agglutination state monitoring sensor due to a change in the raw water state, if the change indicates a shortage of the drug injection amount, the drug injection amount by the drug injection devices 4 and 9 is increased, and the drug injection is performed. When it indicates excess quantity, the control of the chemical injection by the controller 6 is performed so as to reduce the amount of chemical injection by each of the chemical injection devices 4 and 9.

In addition, the injection amount of the inorganic coagulant and the polymer coagulant has a certain degree of correlation in most of the drainage species (for example, when the inorganic coagulant is increased, the polymer coagulant is also increased). Also, depending on the type of coagulant, up to a certain range of the inorganic coagulant input amount, even if the injection amount of the polymer coagulant is maintained at a constant amount, no problem is caused in the coagulation state, and In some cases, this can be achieved by controlling the injection amount of the inorganic coagulant while suppressing the injection amount of the inorganic coagulant directly linked to the cake amount. By setting an arithmetic expression incorporating these conditions in the controller 6 in advance, it becomes possible to perform chemical injection control according to the type of drainage expected to flow.

  In the above description, the coagulation tank is provided in two stages. However, the coagulation tank may be provided in three or more stages, and each may be provided with a chemical dosing device and a coagulation state monitoring sensor for controlling the same.

DESCRIPTION OF SYMBOLS 1 Coagulant injection control device 3,8 Coagulation tank 4,9 Chemical infusion device 5,10 Coagulation state monitoring sensor 6 Controller

Claims (3)

First to n-th chemical infusion devices provided in first to n-th (n is 2 or more) coagulation tanks;
First to n-th aggregation state monitoring sensors provided so as to be able to measure the processing liquid in the first to n-th aggregation tanks;
Having a controller to control the amount of drug injection of each drug injection device based on the detection result of each aggregation state monitoring sensor,
Each aggregation state monitoring sensor has an irradiation unit that irradiates laser light into water, and a light receiving unit that receives scattered light,
The controller is a coagulant injection controller that determines a floc formation state in the coagulation tank from a temporal change of a scattered light intensity signal.   2. The coagulant injection control device according to claim 1, wherein the controller calculates a required amount of the medicine to be injected according to a preset arithmetic expression.   2. The method according to claim 1, further comprising a first coagulation tank in which an inorganic coagulant is dispensed as the first coagulant, and a second coagulation tank in which a polymer coagulant is dispensed as the second coagulant. 3. 2. Coagulant injection control device.

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