CN114460264A - Evaluation method for sludge dewatering performance - Google Patents
Evaluation method for sludge dewatering performance Download PDFInfo
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- CN114460264A CN114460264A CN202110842285.3A CN202110842285A CN114460264A CN 114460264 A CN114460264 A CN 114460264A CN 202110842285 A CN202110842285 A CN 202110842285A CN 114460264 A CN114460264 A CN 114460264A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/02—Biological treatment
- C02F11/04—Anaerobic treatment; Production of methane by such processes
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N11/10—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material
- G01N11/14—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material by using rotary bodies, e.g. vane
Abstract
The invention provides a method for evaluating sludge dewatering performance, which comprises the following steps: obtaining sludge with different rheological properties; anaerobic digestion tests are carried out on the sludge with different rheological properties; determining rheological indexes and dehydration performance of sludge subjected to anaerobic digestion with different rheological properties, and simulating the rheological indexes; and determining the relation between the yield stress and the sludge dewatering performance through correlation inspection. According to the evaluation method of the sludge dehydration performance, the yield stress in the rheological index obtained through experimental measurement can be used for representing the sludge dehydration performance, and a new reference index is provided for evaluating the sludge dehydration rate.
Description
Technical Field
The invention relates to the field of sludge dewatering performance detection, in particular to a method for evaluating sludge dewatering performance.
Background
With the improvement of the material conditions, the production of excess sludge by municipal sewage treatment plants is increasing year by year. The correct treatment and disposal of a large amount of excess sludge and the realization of the rational utilization of the sludge are the hot spots of current research. At present, the anaerobic digestion process, which has the characteristics of reducing the volume and mass of sludge, obtaining methane and facilitating the flow of sludge, has attracted extensive interest of researchers.
Because the sludge is required to be treated to reach a certain water content before being transported outside according to the regulation of environmental regulations, the sludge dewatering capacity influences the operation of sewage plants. Various sludge moisture content detection methods are applied, however, the general method for evaluating the sludge dewatering performance after anaerobic digestion has the problems of low accuracy, complex operation, low repeatability and the like, and meanwhile, the sludge rheological index can reflect the mixing effect and rheological distribution of the sludge in the digester and is paid much attention. Therefore, reasonable inference combined with anaerobic digestion sludge rheology index analysis will increasingly become an important link for sludge treatment and disposal.
In China, sludge with water content of more than 80 percent can be transported only by a dehydration procedure. This is an expensive process, and the cost of which can typically account for 30% to 50% of the annual operating costs of a sewage treatment plant, and if the cost of anaerobic digestion is added, the total cost can even be up to 70% of the annual total operating costs. Therefore, the study on the relationship between the rheological property of the sludge in the anaerobic digestion reactor and the sludge dewatering performance has become a very important research topic.
Disclosure of Invention
The invention aims to provide a novel method for evaluating the sludge dewatering performance, and the yield stress in the rheological index obtained through experimental measurement can be used for representing the sludge dewatering performance.
In order to realize the purpose of the invention, the invention adopts the following technical scheme:
according to an aspect of the present invention, a novel method for evaluating sludge dewatering performance is provided. The evaluation method of the sludge dewatering performance comprises the steps of obtaining sludge with different rheological properties; anaerobic digestion tests are carried out on the sludge with different rheological properties; determining rheological indexes and dehydration performance of sludge subjected to anaerobic digestion with different rheological properties, and simulating the rheological indexes; and determining the relation between the yield stress and the sludge dewatering performance through correlation inspection.
According to an embodiment of the present invention, the sludge with different rheological properties comprises: adding different amounts of inert substances into the sludge with the same physical and chemical properties to obtain the sludge with different rheological properties for subsequent anaerobic digestion tests.
According to an embodiment of the present invention, the inert material is polymethyl methacrylate, and the sludge with different rheological properties is obtained by mixing dewatered sludge and secondary sedimentation tank sludge, and the mixed sludge and digested sludge are mixed according to a VS ratio of 1: 1, and the ratio of the components is 1.
According to an embodiment of the present invention, wherein the anaerobic digestion test for sludge with different rheological properties comprises: anaerobic digestion tests are carried out on the sludge with different rheological properties, and rheological indexes of the sludge after anaerobic digestion are detected, wherein the rheological indexes comprise yield stress, rheological index and consistency coefficient.
According to an embodiment of the invention, in a sequencing batch anaerobic digestion test, the effective volume of an anaerobic digestion reactor is 1.4L, and the temperature of the reactor is 37 +/-1 ℃; stirring by a mechanical stirring facility at the stirring speed of 180 r/min; and carrying out experiments continuously for 20 days, and collecting experimental data in real time.
According to an embodiment of the present invention, the determining rheological indexes and dehydration performances of the sludge after anaerobic digestion with different rheological performances, and the simulating the rheological indexes comprises: after the anaerobic digestion test, rheological indexes and sludge solid content of anaerobic digestion sludge are tested and recorded. And the rheological index was fitted by the Herschel-Bulkley model.
According to an embodiment of the present invention, wherein the rheological index of the anaerobically digested sludge is measured using a rheometer; evaluating the sludge dewatering performance by adopting a centrifugal dewatering mud cake solid content method; using TS20/TS0Evaluating the sludge dewatering performance; and fitting the sludge rheological indexes obtained by the sludge in different anaerobic digestion times by adopting a Herschel-Bulkley model.
According to an embodiment of the present invention, wherein the sludge temperature is maintained at (20. + -. 0.1) DEG C, the rheometer shear rate is set from 0s to 180s-1Increased to 1000s-1The sludge is centrifuged for 20min at 10000rpm, and the centrifugally dewatered mud cake is placed in an oven at 105 ℃ for continuous drying for 24 h.
According to an embodiment of the present invention, the determining the relation between the yield stress and the sludge dewatering performance index through the correlation test comprises: through Pearson correlation Analysis and Principal Component Analysis inspection and Analysis of reaction mechanism, the correlation between yield stress and sludge dewatering performance in rheological indexes is verified, and the possibility of anaerobic digestion sludge yield stress as a novel index for monitoring the sludge dewatering performance is evaluated.
According to one embodiment of the invention, a correlation relationship between rheological index of sludge and dehydration performance after anaerobic digestion is determined by Pearson correlation analysis; carrying out Principal Component Analysis on the influence of rheological indexes on the sludge dewatering performance; and determining whether the yield stress can be used as an index for evaluating the sludge dewatering performance after anaerobic digestion of the sludge through Principal Component Analysis.
One embodiment of the present invention has the following advantages or benefits:
the method for evaluating the sludge dewatering performance comprises the steps of adding an inert substance polymethyl methacrylate into experimental sludge to obtain anaerobic digested sludge with different rheological properties, performing an anaerobic experiment on the sludge by adopting a sequencing batch anaerobic digestion experiment, fitting by adopting a sludge flow curve Herschel-Bulkley model, taking TS20/TS0 as an index for evaluating the sludge dewatering performance, performing pearson correlation Analysis and Principal Component Analysis on the result of the Herschel-Bulkley model, and synthesizing the two Analysis methods to obtain a novel index capable of taking yield stress as a characteristic of the sludge dewatering performance.
Drawings
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
Fig. 1 is a flowchart illustrating a method of evaluating sludge dewatering performance according to an exemplary embodiment.
FIG. 2 is a graph illustrating a change in yield stress during anaerobic digestion of a blank set according to an exemplary embodiment.
FIG. 3 is a graph illustrating a change in yield stress during anaerobic digestion of a first comparative group according to an exemplary embodiment.
FIG. 4 is a graphical illustration of the change in yield stress during anaerobic digestion of a second comparative group, according to an exemplary embodiment.
FIG. 5 is a graphical illustration of a change in yield stress during anaerobic digestion of a third comparative group, according to an exemplary embodiment.
FIG. 6 is a graphical illustration of the change in yield stress during anaerobic digestion of a fourth comparative group, according to an exemplary embodiment.
FIG. 7 is a schematic illustrating sludge dewatering performance after anaerobic digestion according to an exemplary embodiment.
FIG. 8 is a schematic illustrating an anaerobic digestion yield stress versus dewatering performance according to an exemplary embodiment.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.
The terms "a," "an," "the," "said" are used to indicate the presence of one or more elements/components/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.
As shown in fig. 1, fig. 1 is a flow chart of a method for evaluating sludge dewatering performance according to the present invention.
The method for evaluating the sludge dewatering performance of the embodiment of the invention comprises the steps of obtaining sludge with different rheological properties; anaerobic digestion tests are carried out on the sludge with different rheological properties; determining rheological indexes and dehydration performance of sludge subjected to anaerobic digestion with different rheological properties, and simulating the rheological indexes; and determining the relation between the yield stress and the sludge dewatering performance through correlation inspection.
Wherein, the rheological property of the sludge is firstly adjusted to obtain the sludge with different rheological properties under the same physicochemical property. And then carrying out anaerobic digestion experiments on the obtained sludge with different rheological properties, recording experimental data, and simulating rheological indexes to obtain the relation between the rheological indexes and the sludge dewatering performance after the anaerobic digestion experiments. And finally determining whether the yield stress can be used as an index for evaluating the sludge dewatering performance after the anaerobic digestion of the sludge. Physical and chemical properties of the sludge. Physical properties include total solids concentration (TS), suspended solids concentration (VS), etc.; the chemical properties include dissolved chemical oxygen demand (SCOD), alkalinity, pH, and the like. In order to control the physicochemical property to be unchanged, the rheological property of the experimental sludge is only adjusted, so as to better analyze the influence of the rheological property on the dehydration.
In a preferred embodiment of the invention, the sludge to obtain different rheological properties comprises: adding different amounts of inert substances into the sludge with the same physical and chemical properties to obtain the sludge with different rheological properties for subsequent anaerobic digestion tests.
As shown in fig. 1, the sludge was treated before the anaerobic digestion test to obtain sludge with different rheological properties by changing the rheological properties of the sludge by adding different amounts of inert substances.
In a preferred embodiment of the invention, the inert substance is polymethyl methacrylate, and the sludge with different rheological properties is prepared by mixing dewatered sludge and secondary sedimentation tank sludge, and the mixed sludge and digested sludge are mixed according to the ratio of 1: 1, and (b) is prepared.
As shown in fig. 1, PMMA is an english abbreviation of polymethylmethacrylate. And (3) blending the dewatered sludge and the sludge in the secondary sedimentation tank to obtain subsequent test sludge, which is called blended sludge. Digested sludge (inoculated sludge) is taken from an anaerobic digestion reaction tank of the plant, and the sludge treatment process is a thermal hydrolysis-anaerobic digestion process. The dewatered sludge is taken from a dewatering workshop of the plant, and the sludge in the secondary sedimentation tank is taken from a sludge plant A2And a secondary sedimentation tank behind the O process.
In a preferred embodiment of the present invention, anaerobic digestion tests on sludges of different rheological properties include: and (3) performing anaerobic digestion tests on the sludge with different rheological properties, and detecting rheological indexes of the sludge after anaerobic digestion, wherein the rheological indexes comprise yield stress, rheological index and consistency coefficient. By adopting a sequencing batch anaerobic digestion test, the effective volume of an anaerobic digestion reactor is 1.4L, and the temperature of the reactor is 37 +/-1 ℃; stirring by a mechanical stirring facility at the stirring speed of 180 r/min; and carrying out experiments continuously for 20 days, and collecting experimental data in real time.
The experimental data can be collected in real time or periodically. The sequencing batch anaerobic digestion test is a reaction process which is operated intermittently according to time sequence, namely one of several processes which are commonly used in actual production, and the reason for selecting the process is that the process saves space, is convenient to adjust, can realize automatic operation of hardware equipment and is convenient for data collection. The volume of the anaerobic digestion reactor in the experiment is 2L, and the effective volume is 1.4L. The outside of the device is wound by a heating belt, meanwhile, heat preservation cotton is attached to the outside of the heating belt, in order to keep the temperature of the reactor (medium temperature of 37 ℃), the device is provided with a temperature control facility, and the temperature of the reactor is kept to be 37 +/-1 ℃ in the reaction process. The device is provided with a mechanical stirring facility, and the stirring speed of the reactor is 180 r/min; the reaction was carried out for 20 days with periodic collection of experimental data.
FIG. 2 is a schematic diagram showing the variation of yield stress during anaerobic digestion of a blank set provided by the present invention. FIG. 3 is a graph showing the variation of yield stress during anaerobic digestion in a first comparative group according to the present invention. FIG. 4 is a graph showing the variation of yield stress during anaerobic digestion in a second comparative set provided by the present invention. FIG. 5 is a graph showing the variation of yield stress during anaerobic digestion in a third comparative group according to the present invention. FIG. 6 is a graph showing the variation of yield stress during anaerobic digestion in a fourth comparative group according to the present invention.
In a preferred embodiment of the present invention, determining rheological index and dewatering performance of sludge after anaerobic digestion with different rheological properties, and simulating the rheological index comprises: after the anaerobic digestion test, rheological indexes and sludge solid content of the anaerobic digestion sludge are tested and recorded. And fitting the rheological index by a Herschel-Bulkley model. Wherein, a rheometer is adopted to determine the rheological index of the anaerobic digestion sludge; evaluating the sludge dewatering performance by adopting a centrifugal dewatering mud cake solid content method; using TS20/TS0Evaluating the sludge dewatering performance; and fitting the sludge flow curves obtained by the sludge at different anaerobic digestion times by adopting a Herschel-Bulkley model. The temperature of the sludge is kept at (20 +/-0.1) DEG C, and the shear rate of the rheometer is set to be within 180s from 0s-1Increased to 1000s-1The sludge is centrifuged for 20min at the rotating speed of 10000rpm, and the centrifugally dewatered mud cake is placed in an oven at 105 ℃ for continuous drying for 24 h.
Wherein the rheometer uses a Haake Viscotester 550 rotary viscometer. The temperature of the test sludge is kept at (20 +/-0.1) DEG C, and in order to eliminate the memory of the test sludge material and realize repeatable measurement, the sample is pretreated. Then the rheological index of the sludge is measured. The sludge sample in the beaker is introduced into a cup-shaped or cylindrical geometry container, the rheometer shear rate is set from 0s to 180s-1Increased to 1000s-1And collecting and recording data measurement results through rheometer matched software. The sludge dewatering performance is measured by adopting a method of centrifugally dewatering the solid content of a mud cake. And centrifuging the obtained different substrates for 20min at the rotating speed of 10000rpm, and continuously drying the centrifugally dewatered mud cakes in a drying oven at 105 ℃ for 24h to obtain the solid content of the sludge. Using TS20/TS0As an index for evaluating the sludge dewatering performance. Since the Herschel-Bulkley (H-B) model can describe non-Newtonian fluid and covers rheological indexes of ultimate viscosity, flow index, consistency coefficient and yield stress, the rheological behavior of the sludge under static and flowing conditions can be better described, and the model expression is shown in equation (1). The test uses an H-B model to fit the sludge flow curves obtained for different anaerobic digestion times.
τ＝τ0+k·γn (1)
In formula 1, τ represents shear stress, Pa; tau is0Denotes the yield stress, Pa; k is called fluid consistency coefficient, Pa · sn(ii) a Gamma denotes shear rate, s-1(ii) a n represents a streamAnd (4) dynamic index.
The experiment adopts a Herschel-Bulkley model to fit the sludge flow curve, and the fitting condition is shown in a table 1:
TABLE 1 sludge H-B model fitting results in anaerobic digestion process
As can be seen from Table 1 above and with reference to FIGS. 2-6, the degree of fit R2The value range is between 0 and 1, and the fitting degree R is in principle2The closer to 1, the better the goodness of fit, and the more fully the independent variable explains the dependent variable. Degree of fitting R2The values are all larger than 0.970, which indicates that the simulation of the Herschel-Bulkley model on the sludge rheological curve of the research is good. After 20 days of anaerobic digestion, the yield stress of the sludge of the 5 groups of reactors is respectively reduced by 63.71%, 63.61%, 62.67%, 63.36% and 62.53%; the consistency factors are respectively reduced by 75.98%, 64.36%, 65.20%, 48.98% and 56.20%. In addition, the solid content (TS) of the parameters related to the rheology is reduced by 41.48%, 44.06%, 45.88%, 43.54% and 45.89% respectively.
Using TS20/TS0As an index for evaluating the sludge dewatering performance. TS (transport stream)20/TS0More than 1, the sludge dewatering performance becomes good after anaerobic digestion; TS (transport stream)t/TS0The larger the value of (A) is, the more excellent the sludge dewatering performance is. After 20 days of anaerobic digestion, the sludge dewatering performance is ranked as follows: SM-2 > SM-4 > CK > SM-1 > SM-3. Only the SM-2 group values were greater than 1, about 16.7% above the CK group, indicating that the appropriate sludge rheology values, after anaerobic digestion, contribute to improved sludge dewatering performance. Other groups TS20/TS0All were less than 1, indicating poor dewatering of anaerobically digested sludge outside of a certain rheology.
FIG. 7 shows a schematic representation of the sludge dewatering performance after anaerobic digestion provided by the present invention. FIG. 8 is a schematic diagram showing the relationship between yield stress and dehydration performance in anaerobic digestion provided by the present invention.
In a preferred embodiment of the present invention, determining the relationship between yield stress and sludge dewatering performance index by correlation test comprises: through Pearson correlation analysis, Principal Component Analysis (PCA) inspection and reaction mechanism analysis, the correlation between yield stress and sludge dewatering performance in rheological indexes is verified, and the possibility of using the yield stress of anaerobic digestion sludge as a novel index for monitoring the sludge dewatering performance is evaluated. Namely: determining the correlation relationship between the rheological index of the sludge after anaerobic digestion and the dehydration performance by adopting Pearson correlation analysis; carrying out PCA analysis on the influence of rheological indexes on the sludge dewatering performance; and determining whether the yield stress can be used as an index for evaluating the sludge dewatering performance after the anaerobic digestion of the sludge through PCA analysis.
As shown in fig. 1 and fig. 7 to 8, it is difficult to measure the degree of reliability of the estimated value by point estimation alone, and therefore interval estimation is introduced. The method of giving an interval (confidence interval) and predicting that the true parameter exists in this interval with a certain probability is called interval estimation. The probability that this interval can cover the true value is called the confidence limit. The probability that the P value is associated with the statistical hypothesis test. P <0.05 means that given a true pre-established hypothesis, the probability is 0.05 when the test statistic takes a value equal to or exceeding the actually observed extreme value. It is generally significant to have P <0.05, very significant to P <0.01, meaning that the probability that the difference between samples is due to sampling error is less than 0.05 or 0.01. Statistical probabilities for Pearson correlation analysis were obtained by linear regression with a confidence limit of 95% for each correlation. And when the P value is less than 0.05, verifying the correlation between the parameters. The Pearson correlation of sludge rheological properties with sludge dewatering performance is shown in table 2:
TABLE 2 Pearson correlation of sludge rheology with sludge dewatering performance (N ═ 5)
Note: *: indicating significant correlation at the 0.05 level (two-tailed);
**: indicating a significant correlation on the 0.01 scale (two-tailed).
The results show that the yield stress and the dehydration performance (R) of the sludge after anaerobic digestion of the sludge with different rheological initial values20.988, P < 0.01) has strong correlation between the two.
Variance contribution rate as original variable XiWith the first m principal components Y1、Y2、…，YmIs called Y1、Y2、…，YmVariance contribution to original variable Xi. This definition states that the first m principal components extract the original variable XiAnd the contribution rate of the middle variance, so that the capability of the extracted principal component for explaining the original variable can be judged. The cumulative variance contribution rate is one of the variance contribution rates of the selected principal components. The convention generally retains a principal component with λ greater than 1. The results of PCA analysis of sludge dewatering performance are shown in Table 3, and show that the total main component (PCA1) is shared, the characteristic value lambda of PCA1 is 2.125, the principle of the characteristic value (lambda is more than 1) is satisfied, and the cumulative variance contribution rate is 70.849%.
TABLE 3 characteristic values of main components of sludge dewatering Performance
Table 4 shows the components and scores of the sludge dewatering performance factor (PCA1), and it can be seen that the rheological index of the sludge after anaerobic digestion is negative, the yield stress and the consistency coefficient are positive, which indicates that the rheological index of the sludge is the main limiting factor of the sludge dewatering performance, and the yield stress and the consistency coefficient are the main factors.
TABLE 4 sludge dewatering Performance factor Components and score matrices
Linear regression equation: y is1＝0.5645X1-0.5920X2+0.5755X3Wherein, y1The dehydration performance of 5 groups of sludge samples after the anaerobic digestion is finished; x1-yield stress of 5 groups of sludge samples after anaerobic digestion is finished; x2-rheological index of 5 groups of sludge samples after anaerobic digestion is finished; x3The consistency coefficient of 5 groups of sludge samples after the anaerobic digestion is finished. X1，X2，X3Representing the variables normalized to the original, the integrated factor y of dewatering performance1The component coefficients are multiplied by the unknowns represented by the corresponding variables and added. Reflecting that the sludge dewatering performance is influenced by the three variables.
The method for evaluating the sludge dewatering performance comprises the steps of adding an inert substance polymethyl methacrylate into experimental sludge to obtain anaerobic digestion sludge with different rheological properties, performing anaerobic experiments on the sludge by adopting a sequencing batch anaerobic digestion experiment, fitting by adopting a Herschel-Bulkley model of a sludge flow curve, and passing through TS20/TS0The method is used as an index for evaluating the sludge dewatering performance, Pearson correlation analysis and PCA analysis are carried out on results of a Herschel-Bulkley model, and the yield stress can be used as a novel index for representing the sludge dewatering performance by integrating the two analysis methods.
In embodiments of the present invention, the term "plurality" means two or more unless explicitly defined otherwise. The terms "mounted," "connected," "secured," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.
In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or units must have a specific direction, be configured in a specific orientation, and operate, and thus, should not be construed as limiting the embodiments of the present invention.
In the description herein, the appearances of the phrase "one embodiment," "a preferred embodiment," or the like, are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the present embodiment by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.
Claims (10)
1. A method for evaluating sludge dewatering performance is characterized by comprising the following steps:
obtaining sludge with different rheological properties;
anaerobic digestion tests are carried out on the sludge with different rheological properties;
determining rheological indexes and dehydration performance of sludge subjected to anaerobic digestion with different rheological properties, and simulating the rheological indexes; and
and determining the relation between the yield stress and the sludge dewatering performance through correlation test.
2. The method for evaluating sludge dewatering performance according to claim 1, wherein obtaining sludge with different rheological properties comprises:
adding different amounts of inert substances into the sludge with the same physical and chemical properties to obtain the sludge with different rheological properties for subsequent anaerobic digestion tests.
3. The method of evaluating sludge dewatering performance according to claim 2, wherein the inert material is polymethyl methacrylate, and the sludge with different rheological properties is obtained by mixing dewatered sludge and secondary sedimentation tank sludge, and the obtained mixed sludge and digested sludge are mixed according to a VS ratio of 1: 1, and (b) is prepared.
4. The method of evaluating sludge dewatering performance according to claim 1, wherein performing anaerobic digestion tests on sludge of different rheological properties comprises:
anaerobic digestion tests are carried out on the sludge with different rheological properties, and rheological indexes of the sludge after anaerobic digestion are detected, wherein the rheological indexes comprise yield stress, rheological index and consistency coefficient.
5. The method of evaluating sludge dewatering performance according to claim 4,
by adopting a sequencing batch anaerobic digestion test, the effective volume of an anaerobic digestion reactor is 1.4L, and the temperature of the reactor is 37 +/-1 ℃;
stirring by a mechanical stirring facility at the stirring speed of 180 r/min; and
the experiment was carried out continuously for 20 days and experimental data was collected in real time.
6. The method for evaluating the sludge dewatering performance according to claim 1, wherein the rheological index and the dewatering performance of the sludge after anaerobic digestion with different rheological properties are measured, and the simulating the rheological index comprises:
after the anaerobic digestion test, rheological indexes and sludge solid content of anaerobic digestion sludge are tested and recorded. And the rheological index was fitted by the Herschel-Bulkley model.
7. The method of evaluating sludge dewatering performance according to claim 6,
determining rheological index of anaerobic digestion sludge by a rheometer;
evaluating the sludge dewatering performance by adopting a centrifugal dewatering mud cake solid content method;
using TS20/TS0Evaluating the sludge dewatering performance; and
and fitting the sludge rheological indexes obtained by the sludge in different anaerobic digestion times by adopting a Herschel-Bulkley model.
8. The method of evaluating sludge dewatering performance according to claim 7, wherein the sludge temperature is maintained at (20 ± 0.1) ° C, and the rheometer shear rate is set from 0s to 180s-1Increased to 1000s-1The sludge is centrifuged for 20min at 10000rpm, and the centrifugally dewatered mud cake is placed in an oven at 105 ℃ for continuous drying for 24 h.
9. The method of evaluating sludge dewatering performance according to claim 1, wherein determining the relationship between yield stress and sludge dewatering performance index through correlation test includes:
through Pearson correlation Analysis and Principal Component Analysis inspection and Analysis of reaction mechanism, the correlation between yield stress and sludge dewatering performance in rheological indexes is verified, and the possibility of anaerobic digestion sludge yield stress as a novel index for monitoring the sludge dewatering performance is evaluated.
10. The method of evaluating sludge dewatering performance according to claim 9,
determining the correlation relationship between the rheological index of the sludge after anaerobic digestion and the dehydration performance by adopting Pearson correlation analysis;
carrying out Principal Component Analysis on the influence of rheological indexes on the sludge dewatering performance; and
whether the yield stress can be used as a novel index for evaluating the sludge dewatering performance after the anaerobic digestion of the sludge is determined by Principal Component Analysis.
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