CN116067846A - A method for testing the mechanical strength of aerobic granular sludge - Google Patents

Abstract

The invention discloses a method for testing the mechanical strength of aerobic granular sludge, comprising the following steps: using a laser particle size analyzer to cut aerobic granular sludge samples at different rotating speeds, and removing the Points with large deviation; draw the particle size distribution change graph under equal interval action time; use software to analyze and extract the change rate of peak area, etc.

Or change △S information, draw the action time as the abscissa,

Or △S is the scatter diagram of the ordinate, fitting the curve, and characterizing its mechanical strength through curve quantification. Among them, the smaller the change rate (or change amount) of the peak area, the better the mechanical strength of the aerobic granular sludge. The present invention can realize simple and accurate quantitative characterization and standardized test of the mechanical strength of aerobic granular sludge, form a standardized data system, and facilitate the comparison of the mechanical strength of aerobic granular sludge formed in different reactors, in order to further improve The stable operation of the reactor provides a useful reference.

Description

A method for testing the mechanical strength of aerobic granular sludge

Technical Field

The invention belongs to the technical field of wastewater biological treatment, and more specifically, relates to a method for testing the mechanical strength of aerobic granular sludge.

Background Art

Aerobic Granular Sludge (AGS) is a granular activated sludge formed by microbial self-agglomeration under aerobic conditions. Compared with the traditional activated sludge method, AGS technology has the characteristics of high biomass accumulation, good sedimentation performance, ability to resist pollution load shock, and small footprint.

To date, aerobic granular sludge bioreactors include membrane bioreactors (MBRs) and sequencing batch reactors (SBRs). However, the success of these bioreactor designs is related to their ability to form dense granules and maintain high biomass. The tight cell packing in granular aggregates optimizes the interspecies exchange of metabolites, thereby improving overall activity.

However, from the perspective of reactor operation, excessively high/low organic loading rate (OLR) and excessively high hydraulic conditions have a negative impact on the particles, which may lead to lysis and dispersion, a significant reduction in biomass, and ultimately lead to system deterioration or even failure. From the perspective of operating time, AGS is prone to disintegration after long-term operation. Therefore, maintaining the stability of AGS is the key to the stable operation of the reactor, and its mechanical properties are an important indicator to characterize its stability. In general, the mechanical properties of AGS are divided into compression resistance and shear resistance. Existing compression resistance test methods such as a measuring device for the elastic modulus of granular sludge and its measuring method disclosed in Chinese patent CN 104062224 A. The test methods for shear resistance include the integrity coefficient method (using a vibrating screen to judge by measuring the ratio of the solid mass in the supernatant to the total weight of aerobic granular sludge), the instability coefficient method (using an ultrasonic instrument, samples collected at equal intervals are tested for absorbance at a wavelength of 600nm, and the slope of the fitting curve is the instability coefficient), etc. It can be seen that the existing test method has the advantage of rapid measurement, but the collected samples need to be returned in time during the test to prevent the volume change from affecting the experimental results. Therefore, it is particularly important to establish a method that can simultaneously meet the requirements of simple and accurate measurement of its mechanical strength.

Summary of the invention

In order to overcome the defects in the prior art, the present invention provides a method for testing the mechanical strength of aerobic granular sludge, which can realize simple and accurate quantitative characterization and standardized testing of the mechanical strength of aerobic granular sludge.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for testing the mechanical strength of aerobic granular sludge, comprising the following steps:

S1. Use laser particle size analyzer to shear aerobic granular sludge samples at different speeds, and remove points with large deviations through the Dv10/50/90 versus action time graph;

S2. Plotting the particle size distribution change at equal intervals of time t;

或变化量△S的信息，绘制出以作用时间为横坐标，峰面积变化率

或变化量△S为纵坐标的散点图，拟合曲线，通过曲线量化表征好氧颗粒污泥的机械强度；峰面积变化率或变化量越小，表明颗粒在剪切过程中粒径变化较小，则好氧颗粒污泥的机械强度越好。S3. Analyze and extract the peak area change rate from step S2 using software

Or the information of the change △S, plot the peak area change rate with the action time as the horizontal axis

Or a scatter plot with the change △S as the ordinate, a fitting curve is formed, and the mechanical strength of the aerobic granular sludge is quantitatively characterized by the curve; the smaller the peak area change rate or change amount, the smaller the particle size change during the shear process, and the better the mechanical strength of the aerobic granular sludge.

Wherein, S is the area enclosed by the particle size distribution and the x-axis, i.e., the peak area; t is the action time of the particle size distribution test.

The test method provided by the present invention characterizes the mechanical properties of AGS by shear resistance, and quantitatively characterizes the mechanical strength of aerobic granular sludge by the change rate or change amount of particle size distribution peak area, etc., which is conducive to comparing the mechanical strength of aerobic granular sludge formed by cultivation in different reactors, providing a basis for establishing the response mechanism of reactor operating factors and particle mechanical strength, and also providing the optimal solution for cultivating aerobic granular sludge with good strength, which has important practical significance and economic value.

Among them, aerobic granular sludge is not limited to the formation of bioreactor culture; the mechanical strength of aerobic granular sludge can also be called shear resistance, structural stability or mechanical stability.

表征好氧颗粒污泥的机械强度；其中，h为x轴与峰顶点之间的最短距离，即峰高。Furthermore, in step S3, the peak height change Δh or change rate can be used to

Characterizes the mechanical strength of aerobic granular sludge; where h is the shortest distance between the x-axis and the peak apex, that is, the peak height.

表征好氧颗粒污泥的机械强度，其中，d为相邻两个峰顶点之间的距离。Furthermore, the peak value change △d or change rate can be

Characterizes the mechanical strength of aerobic granular sludge, where d is the distance between two adjacent peak vertices.

Furthermore, the mechanical strength of aerobic granular sludge can be characterized by the limiting peak particle size R, wherein R is the peak particle size, specifically representing the limiting peak particle size, which is obtained by a graph showing the change of Dv10/50/90 with the action time.

Furthermore, in step S1, the selected aerobic granular sludge is generally a freshly taken sample, which is first passed through a sieve to remove suspended flocculent sludge, and then mixed evenly using a vortex mixer to ensure the accuracy of the test.

Furthermore, in the step S2, the abscissa is the particle size of the aerobic granular sludge, and the ordinate is the capacity percentage.

Furthermore, in the step S1, the particle size of the aerobic granular sludge before shearing is 200 μm to 3000 μm, preferably 500 μm to 2500 μm.

Furthermore, in the step S1, the rotation speed ω is 500r/min-3500r/min.

Furthermore, in the step S1, the action time is 15min to 90min, and the test is performed at equal intervals of 1.5min to 5min. Preferably, the action time is 30min to 60min, and the test is performed at equal intervals of 1.5min to 2.5min.

Furthermore, in the step S1, the laser particle size analyzer is Malvern MS3000, and the parameters are set as follows: the dispersant is deionized water; the refractive index is 1-2; the absorptivity is 0.05-0.2; and the shading degree is 5-50.

Furthermore, the test results must satisfy the RSD values of Dv10, Dv50, and Dv90 of <10, 6, and 10, respectively, and the fitting weighting <2.5%; wherein Dv10 indicates that 10% of the sample particle sizes are smaller than this value, Dv50 indicates that 50% of the sample particle sizes are smaller than this value, and Dv90 indicates that 90% of the sample particle sizes are smaller than this value.

Compared with the prior art, the beneficial effects are:

1. The present invention adopts a laser particle size analyzer, which is an instrument commonly used to measure particle size, and has the characteristics of being fast, accurate, highly automated, and less affected by concentration and external factors.

2. The test method of the present invention quantitatively characterizes the mechanical strength of aerobic granular sludge by the change amount/change rate of peak area or peak height, and tests and compares the granules generated by different bioreactors at different rotation speeds, which is universal and practical. The present invention can realize simple and accurate quantitative characterization of the mechanical strength of aerobic granular sludge and its standardized test, forming a standardized data system, which is conducive to the comparison of the mechanical strength of aerobic granular sludge cultivated in different reactors, and provides a useful reference for further improving the stable operation of the reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flowchart of the method for testing the mechanical strength of aerobic granular sludge.

FIG. 2 is a graph showing the change in particle size distribution of an embodiment at equal intervals of action time.

FIG. 3 is a fitting curve diagram showing the peak area change rate versus action time of the embodiment.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The present invention is described in one of the embodiments in combination with the specific implementation methods. Among them, the drawings are only used for exemplary descriptions, and only schematic diagrams are shown, not physical drawings, and cannot be understood as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

In the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for exemplary explanations and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances. In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and/or" appearing in the full text is to include three parallel schemes. Taking "A and/or B" as an example, it includes scheme A, or scheme B, or schemes that satisfy both A and B.

Embodiment 1:

As shown in FIG1 , a method for testing the mechanical strength of aerobic granular sludge comprises the following steps:

S1. Use laser particle size analyzer to shear aerobic granular sludge samples at different speeds, and remove points with large deviations through the Dv10/50/90 versus action time graph;

S2. Plotting the particle size distribution change at equal intervals of time t;

或变化量△S的信息，绘制出以作用时间为横坐标，峰面积变化率

或变化量△S为纵坐标的散点图，拟合曲线，通过曲线量化表征好氧颗粒污泥的机械强度；峰面积变化率或变化量越小，表明颗粒在剪切过程中粒径变化较小，则好氧颗粒污泥的机械强度越好。S3. Analyze and extract the peak area change rate from step S2 using software

Or the information of the change △S, plot the peak area change rate with the action time as the horizontal axis

Or a scatter plot with the change △S as the ordinate, a fitting curve is formed, and the mechanical strength of the aerobic granular sludge is quantitatively characterized by the curve; the smaller the peak area change rate or change amount, the smaller the particle size change during the shear process, and the better the mechanical strength of the aerobic granular sludge.

Wherein, S is the area enclosed by the particle size distribution and the x-axis, i.e., the peak area; t is the action time of the particle size distribution test.

The test method provided by the present invention characterizes the mechanical properties of AGS by shear resistance, and quantitatively characterizes the mechanical strength of aerobic granular sludge by the change rate or change amount of particle size distribution peak area, etc., which is conducive to comparing the mechanical strength of aerobic granular sludge formed by cultivation in different reactors, providing a basis for establishing the response mechanism of reactor operating factors and particle mechanical strength, and also providing the optimal solution for cultivating aerobic granular sludge with good strength, which has important practical significance and economic value.

Among them, aerobic granular sludge is not limited to the formation of bioreactor culture; the mechanical strength of aerobic granular sludge can also be called shear resistance, structural stability or mechanical stability.

表征好氧颗粒污泥的机械强度；其中，h为x轴与峰顶点之间的最短距离，即峰高。In the step S3, the peak height change Δh or change rate can also be used.

Characterizes the mechanical strength of aerobic granular sludge; where h is the shortest distance between the x-axis and the peak apex, that is, the peak height.

表征好氧颗粒污泥的机械强度，其中，d为相邻两个峰顶点之间的距离。还能通过极限峰值粒径R表征好氧颗粒污泥的机械强度，其中，R为峰值粒径，此处特别表示极限峰值粒径，是通过Dv10/50/90随作用时间变化图得出。In addition, the peak value can be measured by the change in the peak value △d or the rate of change

Characterize the mechanical strength of aerobic granular sludge, where d is the distance between two adjacent peak vertices. The mechanical strength of aerobic granular sludge can also be characterized by the limiting peak particle size R, where R is the peak particle size, which specifically refers to the limiting peak particle size, which is obtained by the Dv10/50/90 versus action time graph.

Specifically, in step S1, the selected aerobic granular sludge is generally a freshly taken sample, which is first passed through a sieve to remove suspended flocculent sludge, and then mixed evenly using a vortex mixer to ensure the accuracy of the test. In the step S2, the abscissa is the particle size of the aerobic granular sludge, and the ordinate is the volume percentage.

Wherein, in the step S1, the particle size of the aerobic granular sludge before shearing is 200μm to 3000μm. Preferably, it is 500μm to 2500μm. In the step S1, the rotation speed ω is 500r/min-3500r/min. In the step S1, the action time is 15min to 90min; and the test is performed at equal intervals of 1.5min to 5min. The preferred action time is 30min to 60min; and the test is performed at equal intervals of 1.5min to 2.5min. In the step S1, the laser particle size analyzer is MalvernMS3000, and the parameters are set as follows: the dispersant is deionized water; the refractive index is 1 to 2; the absorbance is 0.05 to 0.2; and the shading degree is 5 to 50.

Specifically, the test results must satisfy the RSD values of Dv10, Dv50, and Dv90 of <10, 6, and 10, respectively, and the fitting weighting <2.5%; wherein Dv10 means that 10% of the sample particle sizes are smaller than this value, Dv50 means that 50% of the sample particle sizes are smaller than this value, and Dv90 means that 90% of the sample particle sizes are smaller than this value.

The test method of the present invention quantitatively characterizes the mechanical strength of aerobic granular sludge by the change amount/change rate of peak area or peak height, and tests and compares the granules generated by different bioreactors at different rotation speeds, which is universal and practical. The present invention can realize simple and accurate quantitative characterization of the mechanical strength of aerobic granular sludge and its standardized test, forming a standardized data system, which is conducive to the comparison of the mechanical strength of aerobic granular sludge formed by different reactors, and provides a useful reference for further improving the stable operation of the reactor.

Example 2

The present invention is further described in detail below in conjunction with specific embodiments and drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the equipment used in the present invention is conventional equipment in the art.

At a rotation speed of 2250 r/min, the mechanical strength of aerobic granular sludge with different particle sizes (large and small) in reactor 1 was tested.

A method for testing the mechanical strength of aerobic granular sludge comprises the following steps:

S1. Use laser particle size analyzer to shear aerobic granular sludge samples at different speeds, and remove points with large deviations through the Dv10/50/90 versus action time graph;

S2. Draw a particle size distribution change diagram under equal interval action time t, with the abscissa being the particle size (μm) and the ordinate being the capacity percentage (%);

或变化量△S的信息，绘制出以作用时间为横坐标，峰面积变化率

或变化量△S为纵坐标的散点图，拟合曲线，通过曲线量化表征好氧颗粒污泥的机械强度；峰面积变化率或变化量越小，表明颗粒在剪切过程中粒径变化较小，则好氧颗粒污泥的机械强度越好。S3. Analyze and extract the peak area change rate from step S2 using software

Or the information of the change △S, plot the peak area change rate with the action time as the horizontal axis

Or a scatter plot with the change △S as the ordinate, a fitting curve is formed, and the mechanical strength of the aerobic granular sludge is quantitatively characterized by the curve; the smaller the peak area change rate or change amount, the smaller the particle size change during the shear process, and the better the mechanical strength of the aerobic granular sludge.

Wherein, S is the area enclosed by the particle size distribution and the x-axis, i.e., the peak area; t is the action time of the particle size distribution test.

In this embodiment, in step S1, aerobic granular sludge comes from a rectangular membrane bioreactor 1 (35×25×30cm), and is separated by a plastic mesh to form an aerobic zone and a membrane assembly zone with a volume ratio of 2:1; the influent is artificial synthetic wastewater composed of sucrose (392.7mg/L) and other nutrients; the cultured particles are based on filamentous microorganisms, ellipsoidal, smooth, and mainly brown; the samples are divided into two different particle sizes; the rotation speed is set to 2250r/min, the action time is set to 50min, and the test is performed at equal intervals of 2min; the shading degree of the laser particle size analyzer is set to 10-20, and the test results are shown in Figure 2, and the fitting curve of the peak area change rate obtained by analysis in step S3 versus the action time is shown in Figure 3-a;

Comparing the slopes of the above fitted curves, it can be seen that the slope of the curve corresponding to the small particle size is larger than that of the large particle size, indicating that the mechanical strength of the small particle size AGS is weaker.

Example 3

Mechanical strength test of aerobic granular sludge in reactor 2 at a speed of 2250 r/min

Compared with Example 2, the present embodiment is different in that the AGS used is different. The particles used in the present embodiment come from reactor 2 (4750×2500×3580 mm), which is composed of an aeration zone and a mixing zone. The influent is domestic sewage. The cultured particles are mainly based on calcium ions as the skeleton, showing a lighter internal color and a darker external color. No experimental test of different gradient particle sizes is set, and the action time is set to 32 min. The test results are shown in Figure 2. The fitting curve of the peak area change rate obtained by the analysis of step S3 versus the action time is shown in Figure 3-a. By comparing the slope of the fitting curve with that of Example 1, it can be seen that the AGS formed in reactor 2 has the smallest curve slope within a shorter action time, indicating that the mechanical strength of the formed AGS is the strongest.

Example 4

Mechanical strength test of aerobic granular sludge in reactor 1 at 1500, 2250 and 3000 r/min

Compared with Example 2, the present embodiment is different in that: different gradient rotation speed experimental tests are set, but different gradient particle size experimental tests are not set. The test results are shown in Figure 2, and the fitting curve of the peak area change rate obtained by step S3 analysis versus action time is shown in Figure 3-b; by comparing the slopes of the fitting curves, it can be seen that the slope of the fitting curve of the AGS formed by the reactor 1 increases as the rotation speed gradually increases, indicating that the mechanical strength of the AGS decreases as the rotation speed increases within the range of 1500-3000r/min.

Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims (10)

1. A method for testing the mechanical strength of aerobic granular sludge, characterized in that it comprises the following steps: S1. Use laser particle size analyzer to shear aerobic granular sludge samples at different speeds, and remove points with large deviations through the Dv10/50/90 versus action time graph; S2. Plotting the particle size distribution change at equal intervals of time t; S3. Analyze and extract the peak area change rate from step S2 using software

Or the information of the change △S, plot the peak area change rate with the action time as the horizontal axis

Or the scatter plot with the change △S as the ordinate, the fitting curve is used to quantitatively characterize the mechanical strength of the aerobic granular sludge through the curve; the smaller the peak area change rate or change amount, the better the mechanical strength of the aerobic granular sludge; Wherein, S is the area enclosed by the particle size distribution and the x-axis, i.e., the peak area; t is the action time of the particle size distribution test. 2. The method for testing the mechanical strength of aerobic granular sludge according to claim 1, characterized in that in the step S3, the peak height change Δh or the change rate

Characterizes the mechanical strength of aerobic granular sludge; where h is the shortest distance between the x-axis and the peak apex, that is, the peak height. 3. The method for testing the mechanical strength of aerobic granular sludge according to claim 2, characterized in that the change amount Δd or the change rate of the peak point can also be used.

Characterizes the mechanical strength of aerobic granular sludge, where d is the distance between two adjacent peak vertices. 4. The method for testing the mechanical strength of aerobic granular sludge according to claim 3 is characterized in that the mechanical strength of aerobic granular sludge can also be characterized by the limiting peak particle size R, wherein R is the peak particle size, which specifically represents the limiting peak particle size, and is obtained by a graph showing the change of Dv10/50/90 with the action time. 5. The method for testing the mechanical strength of aerobic granular sludge according to claim 4, characterized in that, in the step S2, the abscissa is the particle size of the aerobic granular sludge, and the ordinate is the volume percentage. 6 . The method for testing the mechanical strength of aerobic granular sludge according to claim 1 , wherein in step S1 , the particle size of the aerobic granular sludge before shearing is 200 μm to 3000 μm. 7. The method for testing the mechanical strength of aerobic granular sludge according to any one of claims 1 to 5, characterized in that in the step S1, the rotation speed ω is 500r/min-3500r/min. 8. The method for testing the mechanical strength of aerobic granular sludge according to any one of claims 1 to 5, characterized in that, in the step S1, the action time is 15 minutes to 90 minutes; and the test is performed at equal intervals of 1.5 minutes to 5 minutes. 9. The method for testing the mechanical strength of aerobic granular sludge according to any one of claims 1 to 5, characterized in that, in the step S1, the laser particle size analyzer is Malvern MS3000, and the parameters are set as follows: the dispersant is deionized water; the refractive index is 1-2; the absorptivity is 0.05-0.2; and the shading degree is 5-50. 10. The method for testing the mechanical strength of aerobic granular sludge according to claim 9, characterized in that: The test results must satisfy the RSD values of Dv10, Dv50, and Dv90 of <10, 6, and 10, respectively, and the fitting weighting <2.5%; wherein Dv10 means that 10% of the sample particle sizes are smaller than this value, Dv50 means that 50% of the sample particle sizes are smaller than this value, and Dv90 means that 90% of the sample particle sizes are smaller than this value.

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