JPS5948653A - Apparatus for measuring putrefaction degree of sludge - Google Patents

Abstract

PURPOSE:To simply and rapidly measure the putrefaction degree of sludge, by a method wherein a noble metal electrode and a reference electrode for measuring the redox potential of sludge, a glass electrode and a reference electrode for measuring a pH value and a temp. electrode for measuring a temp. are provided and outputs of these electrodes are subjected to operation treatment. CONSTITUTION:A sensor part 21 is immersed in sludge while the output terminal 7 of an earth electrode 1 is earthed and the redox potential of the sludge is measured through output terminals 8, 9 by a noble metal electrode 2 and a reference electrode 3 and the pH value of the sludge is measured through output terminals 10, 9 by a glass electrode 4 and a reference electrode 3 while the temp. of the sludge is measured through an output terminal 11 by a thermistor temp. electrode 5. The measured data from these electrode are subjected to operation treatment by an operation treatment mechanism 22 to output a sludge decomposition degree. By this method, the sludge putrefaction degree is simply and rapidly measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sludge putrefaction degree measuring device for measuring the putrefaction degree of sludge in a sludge thickening tank in activated sludge water treatment.

Conventionally, in order to detect the putrefaction state of sludge, the sludge particles, size distribution and average particle size, sludge settling properties, sludge centrifugal dewatering properties, COD and BOD of the water surrounding the sludge, the amount of soluble substances in the sludge, color,
The degree of putrefaction of sludge was determined individually by integrating the analysis and measurement results of a series of factors that affect sludge properties, such as odor.

As mentioned above, the degree of sludge putrefaction has traditionally been determined by integrating the measured and analyzed values of many factors, so it takes a lot of time to determine the degree of putrefaction, and the analysis items and methods differ depending on the type of sludge. Due to the complexity of the sludge situation in the sludge thickening tank,
This has become a fatal weakness for automation.

This invention was made to eliminate the drawbacks of the conventional methods as described above, and includes a noble metal electrode for measuring the redox potential of sludge, a glass electrode for measuring the hydrogen ion concentration of sludge, and a glass electrode for measuring the hydrogen ion concentration of sludge. The system is equipped with a sensing section consisting of a reference electrode used in combination with the above two electrodes and a thermistor temperature electrode for measuring the temperature of the sludge, and a calculation section that calculates the degree of putrefaction of the sludge from these measured values. It is an object of the present invention to provide a sludge putrefaction degree measuring device that can easily and quickly measure the putrefaction degree and output the measured value as an electric signal.

First, the principle of the present invention will be explained using as an example the sludge accumulated in a thickened sludge tank among sewage sludge. For example, as reported in P161-181 of the Report of the Testing Department of the Sewage Works Corporation, as the residence time of sludge in the final sludge tank increases, the dewatering and thickening properties of the sludge may decrease. It is known,
The cause is believed to be the progress of decomposition of the sludge. Therefore, in order to efficiently thicken sludge, it is necessary to detect the degree of putrefaction of the sludge and optimally manage the thickening tank, but as mentioned above, conventional methods have the drawback of requiring a large amount of time for this detection. It has not been put to practical use.

On the other hand, the inventors of the present invention have newly clarified the relationship between the corrected oxidation-reduction potential of sludge (hereinafter abbreviated as corrected ORP value) and various variables representing the degree of putrefaction of sludge. The relationship is summarized as follows.01) As shown in Figure 1, due to sludge decay, the characteristic values that indicate the condition of the sludge, such as dewaterability, thickening ability, and pH value, decrease; It does not decrease uniformly as time progresses, but at a certain fixed time (
tl) shows an almost constant value, and its ffl?
'J's waiting time also gradually decreases.

2) The above specific time constraints include sludge concentration, temperature, and modified equilibrium ORP.
Determined by value.

3) The corrected balanced ORP value is the value obtained by further correcting the OH2 value based on the hydrogen electrode with respect to the reference pH (for example, pa7).

4) The positive average ORP value is determined by oxygen supply conditions to sludge, temperature, sludge concentration, etc.

5) From 1) to 4), there is a certain relationship between the modifier #ORP value and each variable representing the degree of putrefaction of sludge, as shown in FIG. In the figure, A is a curve showing the modified ORP, and B is a curve showing sludge dewaterability.

Concentrated f! In the case of accumulated sludge, since the residence time of such sludge is long, the ORP IIIt of the sludge has already reached a balance. Therefore, by simultaneously measuring 0kLPIlii, pH value, and temperature, and performing arithmetic processing using these results, the corrected equilibrium 00RP value can be immediately obtained.
As a result, the degree of putrefaction within the thickening tank can be determined.

An embodiment of the present invention will be described below based on the drawings. The sludge putrefaction degree measuring device of the present invention is composed of a sensor (21) and an arithmetic processing mechanism (22), as shown in the block diagram of FIG. The sensor (21) is composed of various types of electrodes as shown in Figure 4, and is used to obtain characteristic values representing the chemical and physical state of sludge necessary for determining the degree of sludge putrefaction as electrical signals. It is. On the other hand, the arithmetic processing mechanism (22) /'i in this embodiment is constituted by a 4-bit microcomputer, performs the following arithmetic operations, and outputs the degree of sludge putrefaction as an electrical signal.

1) pH under standard conditions (20°C, 1 atm) from each electrode
value, convert to OH2 value.

2) Find the pH value that deviates from the standard pH value (pH 7),
Subtract 50 millivolts from the OH2 value with pH deviation IK.

3) The above results are taken as the sludge corrosion rate, and the larger the value, the lower the corruption degree. Normally, the degree of putrefaction indicates a negative potential, and this is considered to be the way electricity is produced.

Next, the sensor (21) will be explained. In Figure 4, (1) R earth electrode, (2) noble metal electrode, (3)
u reference electrode, (4) is a glass electrode, (5) is a thermistor temperature electrode, (6) is a support to unite these electrodes, and the following terminals are used to enable signal supply to the outside. has. (7) is the earth output terminal, (8) is the noble metal electrode output terminal, (9) is the reference electrode output terminal, (1o)
(11) is the temperature electrode output terminal.

Next, the movement 11r= will be explained. The above sensor (21)
When immersed in sludge, a potential is generated from each electrode due to an electrochemical reaction in the sludge. (However, the earth electrode (11) is for matching with an external device, and the temperature electrode (5) outputs only resistance changes.) The following information is obtained electrochemically from each of these potentials.

1) OH binary value of sludge Determined from the potential difference between the noble metal electrode (2) and the comparison electrode (3).

η pH value of sludge Determined from the potential difference between the glass electrode (4) and the comparison electrode (3).

3) Sludge temperature It is determined by the resistance value of the thermistor temperature electrode (5).

In addition, as shown in FIG. 4, the sensor (21) in the above embodiment has a ground electrode (1), a noble metal electrode (2), a reference electrode (3), a glass electrode (4), and a thermistor temperature electrode (5).
Although a sensor (21) fixed to a support body (6) was used, a sensor (21) whose entire structure is made of glass may be used as shown in FIGS. 5 and 6.

As explained above, the present invention includes a noble metal electrode for measuring the redox potential of sludge, a glass electrode for measuring the hydrogen ion concentration of sludge, a ratio electrode used in combination with the above electrode for comparison of these measurements, and a sludge electrode. Equipped with a sensing section consisting of a thermistor temperature electrode for temperature measurement, and a calculation section that calculates the degree of sludge putrefaction from these measured values, it is possible to easily and quickly measure the degree of sludge putrefaction. This has the effect of making it possible to output the value as an electrical signal.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between sludge particle size distribution, solubility, COD, pH 1 dewaterability, thickening ability, etc. and sludge residence time.
Fig. 2 is a characteristic diagram showing the relationship between sludge corrected equilibrium 0flP, dewaterability and sludge retention days, Fig. 3 is a Glock diagram showing an embodiment of the present invention, and Fig. 4 is a sensor shown in Fig. 3. FIG. 6 is a side view showing one embodiment of the part, FIG. 6 is a sectional view showing another embodiment of the sensor part, and FIG. 5 is a sectional view taken along line AA in FIG. In the figure, (21) is a sensor, (22) is an arithmetic processing mechanism, (2) is a noble metal electrode, (3) is a comparison electrode, (4) is a glass electrode, and (5) is a thermistor temperature electrode. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 297- Figure 4 Figure 5-17,7 ・'' From 5 Procedural amendment (white) Mr. Commissioner of the Japan Patent Office 1, Indication of case Patent application Showa 57-160086 No. 2
, Name of the invention Sludge Putrefaction Degree Measuring Device 3, Relationship with the case of the person making the amendment Patent Applicant Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Jinhachibe Katayama 4. Agent address: Mitsubishi Electric Corporation, 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (6699) Patent attorney Shin Kuzuno
-5. Column 6 of the detailed description of the invention in the specification subject to amendment. Contents of the amendment In page 4, line 20 of the specification, ``1 modified equilibrium 00RP value'' is corrected to ``1 revised equilibrium ORP value''. that's all

Claims (2)

[Claims] (1) A precious metal electrode for measuring the redox potential of the sludge, a glass electrode for measuring the hydrogen ion concentration of the sludge, a reference electrode used in combination with both of the electrodes for these measurements, and a reference electrode for measuring the hydrogen ion concentration of the sludge. Temperature electrodes in the temperature measurement chamber, these readings are contaminated (2) The sludge putrefaction degree measuring device according to claim 1, characterized in that a comparison electrode is used in common when measuring the redox potential and hydrogen ion concentration of sludge.