JPH06206100A - Device for dewatering of sludge - Google Patents

Abstract

PURPOSE:To optimize the amt. of a flocculant being applied to sludge and stabilize the operation of a sludge dewatering device based on the optimized amt. by a method wherein the loading amt. of solid is obtained by integrating the values measured by a raw sludge flow meter and a SS concn. meter and the applied amt. of the flocculant is regulated based on the result obtained from a comparison computation made between the aforesaid loading amt. of solid and the value measured by a heat transfer detector. CONSTITUTION:The sludge dewatering device adapted to add a flocculant in a tank 3 to raw sludge in a pit 1 and separate the sludge into the dewatered cake and filtrate by a dehydrator 5 is provided with a heat transfer detector 10 so disposed as to make contact with dewatered filtrate in a filtrate tank 9, a raw sludge flow meter 7 for measuring the amt. of raw sludge fed and a SS concn. meter 6 for measuring the SS concn. of the raw sludge. An arithmetic and control unit 8 is further provided which makes a computation of the loading amt. of solid by integrating the values measured by the raw sludge flow meter 7 and the SS concn. meter 6 and makes a comparison computation between the result obtained from the loading amt. computation and the value measured by the heat transfer detector 10 and, based on the result from the comparison computation, regulates the amt. of the flocculant applied to the sludge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge dewatering device,
More specifically, the present invention relates to a sludge dewatering device that enables efficient use and stable operation of the coagulant by controlling the amount of coagulant to be dispensed optimally.

[0002]

2. Description of the Related Art In the sludge dewatering process, in order to improve the dewaterability of the sludge, a centrifugal dewatering machine or a coagulation reaction tank in which a sludge pipe or a dewatering machine main body is dosed to separate it into a dehydrated cake and a dehydrated filtrate. For example, a predetermined amount of an organic polymer coagulant is added to the raw sludge that is supplied to the raw sludge to proceed with the coagulation reaction, and the coagulated sludge thus tempered is transferred to, for example, a belt press type dehydrator to be dehydrated. As a result, an operation of separating the dehydrated cake and the dehydrated filtrate is performed.

In this case, if the amount of the coagulant to be fed to the raw sludge is too small, the coagulation becomes insufficient, and, for example, in a belt press type dehydrator, solid-liquid separation by gravity filtration becomes poor, and the coagulated sludge becomes poor. Flow out to the side of the filter cloth, and in the centrifugal dehydrator, the solids recovery rate decreases and the cake water content increases, making it impossible to dehydrate. On the other hand, if the coagulant is too much, the chemical will be consumed wastefully, and the coagulant will remain in the coagulated sludge conditioned especially in the belt press dehydrator. The agent attaches the dehydrated cake to the belt of the dehydrator to deteriorate the peelability of the dehydrated cake, resulting in a decrease in the recovery rate of the dehydrated cake.

From the above, operating the dehydrator by appropriately controlling the coagulant dosing amount stabilizes not only the efficient use of the coagulant but also the operation state of the entire apparatus. However, it is also required in terms of labor saving of equipment operation management work. Conventionally, regarding the control of the chemical injection amount of the flocculant, a method of controlling the chemical injection amount in proportion to the SS (solid content) concentration of the raw sludge to be supplied has been put into practical use.

However, since the conventional control system indirectly measures the chemical injection amount by measuring the property (SS concentration) of the raw sludge having a specific property before chemical injection, in practice, for example, It is extremely difficult to apply it to raw sludge in which the sludge type and sludge properties change from moment to moment. In order to solve such a problem, the present inventors, with respect to the coagulated sludge after chemical coagulation of the coagulant, directly grasp the coagulated state of the coagulated sludge as a heat transfer detection value of the dehydrated filtrate, A method has been proposed in which the amount of drug injection is controlled based on the detected value (see Japanese Patent Laid-Open No. 2-290205).

[0006]

By the way, the agglomeration processing apparatus of the above-mentioned Japanese Patent Laid-Open No. 2-290205 is shown in FIG. 1 which is a conceptual schematic view of FIG. 5 or FIG. 6 described therein. The operation is controlled on the premise of such a relationship between the coagulant chemical injection rate and the heat transfer detection value in the test liquid. That is, by measuring the heat transfer detection value of the dehydrated filtrate,
This is a method of reading and determining the drug injection rate corresponding to the measured value from FIG.

However, as is apparent from FIG. 1, when the heat transfer detection value of the dehydrated filtrate changed from the B value in the figure to the A value, this change caused the chemical injection rate to change from the b value to the a value. It is difficult to determine whether the result is based on the result or the result of changing from the b value to the c value. In other words, it is not possible to judge whether the coagulant is in the chemical injection rate of excess or deficiency only by measuring the change in the heat transfer detection value of the dehydrated filtrate, and therefore, it is impossible to control the chemical injection accurately.

An object of the present invention is to provide a sludge dewatering device which solves the above-mentioned problems in the chemical injection control device described in Japanese Patent Application Laid-Open No. 2-290205 and enables more precise chemical injection control.

[0009]

[Means for Solving the Problems] In the case of the above-mentioned chemical injection control device, the heat transfer detection value of the dehydrated filtrate is only information that represents the aggregated state of the aggregated sludge that produces the dehydrated filtrate as a whole. However, the increase / decrease state of the coagulant in the coagulated sludge cannot be accurately determined from the information.

Therefore, for the above-mentioned detected value of heat transfer, other factors indicating the aggregation state of the aggregated sludge, for example,
By obtaining the information on the solid load and comparing the information with the information on the heat transfer detection value described above, the increase / decrease state of the coagulant in the coagulated sludge can be more accurately grasped. That is, when the solid load is increasing, the change in the heat transfer detection value from the B value to the A value in FIG. 1 corresponds to the change from the b value to the a value in the chemical injection rate. Also, when the solid load is decreasing, it can be determined that the change from the B value to the A value corresponds to the change from the b value to the c value.

The sludge dewatering device of the present invention was developed on the basis of the above idea. That is, the sludge dewatering device of the present invention is a sludge dewatering device that adds a coagulant to the raw sludge to separate the sludge into a dehydrated cake and a dehydrated filtrate, and a heat transfer detection device arranged so as to come into contact with the dehydrated filtrate. Meter, a raw sludge flow meter that measures the amount of the raw sludge supplied, an SS concentration meter that measures the SS concentration of the raw sludge, and the measured values of the raw sludge flow meter and the SS concentration meter are integrated. A solid state load is calculated, and the calculation value and the measured value of the heat transfer detector are compared and calculated, and an arithmetic controller that controls the chemical injection amount of the coagulant based on the obtained calculated value is included. Is characterized by.

[0012]

In the case of the apparatus of the present invention, the heat transfer detector provided in the dehydrated filtrate obtains information on the overall coagulation state of the coagulated sludge. However, that information does not determine the increase or decrease state of the dosing rate of the aggregating agent, as described above with reference to FIG. In the device of the present invention, in addition to the measurement of the heat transfer detection value, the supply amount of the raw sludge is further measured by the raw sludge flow meter, and SS
The solids load is calculated by measuring the SS concentration of the raw sludge with a densitometer, inputting the measured values of both to the arithmetic controller, and integrating them.

Therefore, it is possible to determine the increase / decrease state of the drug injection rate based on this calculation information and accurately perform the drug injection control based on the determination.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic diagram showing the basic configuration of the sludge dewatering device of the present invention. The case of a belt press type dehydrator will be described below. In the figure, the raw sludge is supplied from the raw sludge pit 1 to the coagulation reaction tank 2 through the pipe p _1, and at the same time, the coagulant flows from the tank 3 through the pipe p _{2 in} a state where the flow rate is adjusted by the chemical injection pump 4. Is coagulated into the coagulation reaction tank 2, and the coagulation sludge is conditioned by the coagulation reaction of both.

The conditioned coagulated sludge is transferred to the belt press dehydrator 5 through the pipe p ₃ and separated into a dehydrated cake and a dehydrated filtrate. In the device of the present invention, the SS concentration meter 6 and the raw sludge flow meter 7 are inserted in series in the middle of the pipe p ₁ , and the SS concentration and the supply amount of the raw sludge supplied from the pit 1 are measured every moment. Then, the measured values are input to the arithmetic controller 8, where both measured values are integrated to calculate the solid load amount in the raw sludge.

As the SS densitometer and the raw sludge flowmeter, any one can be used as long as it is usually used. In the case of the SS densitometer, for example, an ultrasonic densitometer, a near infrared densitometer, a micro A wave type densitometer and the like can be used, and in the case of the raw sludge flowmeter, an electromagnetic flowmeter, a Doppler flowmeter, a hot wire flowmeter and the like can be mentioned. Part of the dehydrated filtrate separated by the dehydrator 5 is collected in the filtrate storage tank 9 through the pipe p ₄ . The collected dehydrated filtrate is agitator 9a
And the heat transfer detector 10 is disposed therein to contact the dehydrated filtrate. Here, as the heat transfer detector, the one described in detail in JP-A-2-290205 may be used as it is.

The heat transfer indicator 10 measures a heat transfer detection value of dehydrated sludge in which SS and the like are uniformly dispersed, and inputs the measured value to the arithmetic and control unit 10. The filtrate storage tank 9 has a thermometer 11 and an electric conductivity meter 1 as shown in FIG.
2, an SS concentration meter 13 and the like are attached to collect other information about the coagulated sludge to be managed, and to collect these information, the arithmetic controller 10
You may enter it in.

A part of the filtrate storage tank 9 of this embodiment may be sampled and measured in another tank. The device of the present invention operates as follows. For example, the arithmetic controller 8
In, it is assumed that the measurement value of the heat transfer detector 10 has changed from the B value in FIG. 1 to the A value.

This change indicates either a change in the chemical injection rate from the b value to the a value or a change in the chemical injection rate from the b value to the c value in FIG. However, it does not determine which is the case. Here, the change in the solid load amount of the raw sludge obtained by integrating the measured value of the SS concentration meter 6 and the measured value of the raw sludge flowmeter 7 is taken into consideration.

That is, when the solids load is increasing, the state of chemical injection into the raw sludge is from the value b in FIG. 1 to the value a.
It is determined that the value has changed. Therefore, in that case, the arithmetic controller 8 may send a signal to the chemical injection pump 4 to increase the chemical injection amount from the tank 3. Also,
If the solid load is decreasing, it is determined that the chemical injection state of the raw sludge is changing from the b value in FIG. 1 to the c value. Therefore, in that case, the arithmetic controller 8 may send a signal to the chemical injection pump 4 to reduce the chemical injection amount from the tank 3.

[0021]

As is apparent from the above description, the device of the present invention is the device of Japanese Patent Laid-Open No. 2-290205, and is further provided with a means for judging the increase / decrease of the solid load amount of raw sludge. As compared with the case of the chemical injection control only by the measurement value of the heat transfer detector, the chemical injection control with higher accuracy becomes possible.

Therefore, it becomes possible to optimize the chemical injection amount of the coagulant and stabilize the operation of the apparatus based on it, and its industrial value is great.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a detected value of heat transfer and a chemical injection rate of an aggregating agent.

FIG. 2 is a schematic diagram showing a basic configuration of an example of the apparatus of the present invention.

[Explanation of symbols]

1 Raw sludge pit 2 Flocculation reaction tank 3 Flocculant tank 4 Chemical injection pump 5 Dehydrator 6 Raw sludge SS concentration meter 7 Raw sludge flow meter 8 Operation controller 9 Filtrate storage tank 9a Stirrer 10 Heat transfer detector 11 Temperature Total 12 Electric conductivity meter 13 SS concentration meter p ₁ ~ p ₄ Piping

Claims (1)

[Claims] 1. A sludge dewatering device for adding a coagulant to raw sludge to separate the sludge into a dehydrated cake and a dehydrated filtrate, and a heat transfer detector arranged so as to be in contact with the dehydrated filtrate, and the original sludge. Of sludge flowmeter for measuring the amount of supply of solid sludge, SS concentration meter for measuring SS concentration of the raw sludge, and measurement values of the raw sludge flowmeter and the SS concentration meter are integrated to calculate a solid load amount. Then, the calculated value and the measured value of the heat transfer detector are compared and calculated, and the sludge is characterized by having an arithmetic controller for controlling the chemical injection amount of the coagulant based on the obtained calculated value. Dehydrator.