CN104458518B - Method for monitoring and qualitatively and quantitatively analyzing sediments in small-caliber sewer line - Google Patents

Abstract

A method for monitoring and qualitative and quantitative analysis of sediments in small-diameter sewage pipes. The principle of the method is: without the action of microorganisms, the sediments mainly come from SS in the water. Based on this principle, first select a short distance For small-diameter pipelines, samples are regularly taken from inspection well 1 connected to the pipeline, and inspection well 2 is sampled at the same time according to the time when the water flow reaches inspection well 2, and the SS settlement rate between the two inspection wells is calculated to determine the deposition of sediments Then, measure the routine indicators of the sample, and find significant degradation by comparing the changes of different indicators, so as to determine the material composition contained in the sediment. Next, measure the particle size distribution in the water sample, judge the particle size composition of the sediment in the small-diameter pipeline according to the change of the particle size distribution, and finally obtain the sediment accumulation between the inspection well 1 and the inspection well 2 according to the formula. The invention is suitable for the research of the sediments in the non-split and confluence pipes with pipe diameters below 300mm.

Description

A Method for Monitoring and Qualitative and Quantitative Analysis of Sediments in Small Diameter Sewage Pipelines

technical field

The invention belongs to the technical field of sewage treatment, in particular to a method for monitoring and qualitatively and quantitatively analyzing sediments in small-diameter sewage pipes.

Background technique

Urban drainage pipes are an important part of urban drainage systems. During sewage transportation, due to the diversity of particulate matter types entering the pipes with sewage or rainwater and the randomness of pipe flow changes, almost all urban drainage pipes have varying degrees of pollutant deposition. Phenomenon. However, the above-mentioned sediments will not only reduce the water delivery capacity of the pipeline, but also will be washed and released with the uneven flow rate, which will increase the pollutant load of the pipeline and seriously threaten the water environment of the receiving water body. Therefore, it is of great significance to study the properties and deposition amount of sediments.

However, there are many types of urban sewage pipe networks, and the water conservancy conditions such as pipe diameter and slope are different, and the sediment will increase or decrease correspondingly with the change of hydraulic conditions. Therefore, there are few studies on monitoring methods for pipeline sediments, which are limited to the analysis of sediment characteristics and qualitative and quantitative monitoring of large-diameter pipe sections.

At present, for the sediment monitoring and analysis of the large-diameter sewage pipe section, only the pipeline robot is used to go deep into the pipeline to take samples, and the sonar probe installed on the robot generates the sediment inside the pipeline and the pipeline on the monitor connected to it. real-time images. The small-diameter pipeline has a small diameter, and the flow rate and water depth are not large, which not only directly leads to the inability of the robot to smoothly enter the pipeline for sampling, but also prevents the sonar probe from being completely submerged below the water level. Therefore, it is impossible to take out the deposits of small-diameter pipelines for property analysis, and it is also impossible to obtain the deposition status of the deposits.

Therefore, this patent is of great significance for monitoring the content of small-diameter sediments and exploring the properties of sewage pipe network sediments.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a method for monitoring and qualitative and quantitative analysis of sediments in small-diameter sewage pipes, which improves the monitoring and analysis of sediments in urban sewage pipe networks, and achieves the goal of perfecting urban sewage. The purpose of pipe network sediment monitoring and analysis.

In order to achieve the above object, the technical scheme adopted in the present invention is:

Select a short-distance, non-converging and diverging pipeline 3, and take regular samples from the inspection well 1 connected to the pipeline 3. At the same time, use a flowmeter to measure the flow and velocity of the water flow there, and get the water flow to the inspection well 1 according to the spacing and flow velocity. The time of inspection well 2 2 downstream, and sampling in inspection well 2 2 at this time. Then according to the formula Calculate the sedimentation rate of SS during the period, where D is the sedimentation rate, unit mg/L s; SS ₁ is the measured value of SS at 1 place in inspection well 1, unit mg/L; SS ₂ is the measured value of SS at 2 places in inspection well 2, The unit is mg/L; S is the distance between the inspection well 1 and the inspection well 2, the unit is m; v is the flow velocity of the water flow between the inspection well 1 and the inspection well 2, the unit is m/s; according to the The sedimentation rate is obtained by the sedimentation rate, and the conventional indicators and particle size distribution of the water flow are measured at the same time, so as to conduct qualitative analysis and judgment on the sediments in the pipeline, and the inspection well is obtained according to the formula M _deposition = (SS ₁ -SS ₂ )·Q·Δt The _sediment accumulation amount M between inspection well 1 and inspection well 2 2, where Q is the average flow rate in the pipeline, and Δt is the interval time of sampling from inspection well 1 and inspection well 2.

Secondly, measure the routine indicators of water quality in the samples of inspection well 1 and inspection well 2. Routine indicators include total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ -N), and chemical oxygen demand (COD). Determination can also be measured by the national standard method. By comparing the changes of different indicators, it is found that the specific indicators that are significantly degraded (average degradation is about 30%), so as to obtain the main components of the sediments.

Then, particle size analysis instrument or sieving method is used to measure the particle size change, and based on the particle size change status, the particle size composition of sediments under different flow rates and flow rates in different time periods is analyzed.

In the present invention, based on the SS, flow velocity v and flow Q measured regularly to the inspection well one 1 and the inspection well two 2, the horizontal axis is drawn as a curve of time, and the least square method is used to analyze the inspection well one 1 and the inspection well two 2 The SS, flow velocity v and flow Q are used for formula fitting. The pipe 3 has a pipe diameter below 300mm and has no diversion and confluence functions.

Compared with the prior art, the present invention is suitable for the research on the sediments in the pipe section with a pipe diameter below 300mm. By monitoring and calculating a series of indexes such as the conventional indexes, SS difference and particle size distribution of the water samples taken, the obtained Study the properties of the sediments in the pipe section and the overall situation of the sedimentary characteristics, so as to have a deeper understanding of the transformation of pollutants in it. This method avoids the adverse effect of the original method on the study of small-diameter sediments, improves the scope of sediment research, and scientifically explores the properties of small-diameter sediments through indirect methods.

Description of drawings

Figure 1 is a schematic diagram of the study of SS changes in water quality in pipelines using the Wendehua classification standard for marine sediments.

Fig. 2 is a schematic diagram of the sampling principle of the present invention.

Fig. 3 is a diagram of the median particle size distribution of Example 1 of the present invention.

Figure 4 is the concentration diagram of five conventional indicators in the embodiment of the present invention, Figure 4a is the concentration of TN, Figure 4b is the concentration of NH ₄ ⁺ -N, Figure 4c is the concentration of NO ₃ -N, Figure 4d is the concentration of COD, and Figure 4e is the concentration of TP concentration.

Fig. 5 is a graph showing the median particle size distribution of Example 2 of the present invention.

detailed description

The implementation of the present invention will be described in detail below in conjunction with the drawings and examples.

The principle of the invention is: under the condition of not considering the action of microorganisms, the variation of SS in the pipe network is the variation of sediment in the pipeline, as shown in the formula (1).

M _deposition = (SS ₁ -SS ₂ )·Q·Δt (1)

Based on the above principles, the present invention uses the Wendehua classification standard for marine sediments to study the SS changes in water quality in pipelines (as shown in Figure 1), and finds that particles with D<4 μm are the easiest to wash away, and particles with D>63 μm begin to deposit. And the larger the particle size, the better the deposition, and the particle size D>125μm is the easiest to deposit. Other studies have shown that the sediment in the pipeline is settled by gravity, and the greater the flow rate, the worse the settlement effect and the better the scouring effect.

According to above-mentioned principle and sediment characteristic, the present invention is applicable to:

1) There is no confluence and diversion pipeline;

2) Pipelines with short flow times and small pipe sections.

Therefore, as shown in Fig. 2, in the implementation process of this method, a pipeline suitable for the above conditions is firstly selected. And select the qualified inspection well 1 and inspection well 2 2. On this basis, the inspection well 1 and the inspection well 2 2 are regularly sampled and the flow rate is monitored. The sampling rules are: the sampling of the inspection well 2 2 must be carried out after the sampling of the inspection well 1 1 and the water flow reaches the inspection well 2 2 at intervals. time. After sampling, according to the SS of inspection well 1 and inspection well 2, the sediment deposition rate in each time period is calculated, and the results reflect the sediment deposition state. Its formula is:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: D——sedimentation rate (mg/L s)

SS ₁ ——measured value of SS in inspection well 1 (mg/L)

SS ₂ ——measured value of SS at 2 places in inspection well 2 (mg/L)

l——Inspection Well Spacing (m)

v——Instant velocity (m/s)

Then, based on the samples collected above, routine monitoring of water quality indicators is performed on the inspection well 1 and the inspection well 2 2 in the pipeline 3 . Routine indicators include total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ -N), and chemical oxygen demand (COD). Determination can also be measured by the national standard method. By comparing the changes of different indicators, it is found that the specific indicators that are significantly degraded (average degradation is about 30%), so as to obtain the main components of the sediments.

Next, use a particle size analysis instrument or a sieving method to measure the particle size change, and analyze the particle size composition of the sediment under different flow rates and flow rates in different time periods based on the particle size change status.

Finally, determine the sediment content in small diameter pipes. In this method, the formula for the amount of sediment deposited based on the principle is:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

t ₀ is the initial test time, t is the end time, Q(t) is the flow fitting function, SS ₁ (t) is the SS fitting function of inspection well 1 point 1, SS ₂ (t) is the SS fitting function of inspection well 2 point 2 SS fitting function, V(t) is the velocity fitting function.

The specific solution method is as follows:

1) Regularly measure the SS, flow velocity v and flow Q of inspection well 1 and inspection well 2, and draw a curve with the horizontal axis as time.

2) Use the least squares method to fit the SS, flow velocity v and flow Q curves of inspection well 1 and inspection well 2 2, and ensure that the R ² after the period fitting meets the requirements of relevant regulations.

3) Bring the fitting equation into the corresponding equation to solve. Complicated formulas can be integrated by computer (random point finding method, rectangle solution method, definition method, etc.), and the integral result is the amount of pipeline sediment deposition.

It should be pointed out that formula (3) has the following two special cases, under which the calculation process can be directly simplified:

1. The deposition rate of the sediment under the steady state of flow velocity and flow

In this state, the flow rate remains stable, and the amount of sediment deposited at this time can be expressed as:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Q</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

When the distance is very short, within a certain error range can be ignored, at this time formula (4) can be further simplified as:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Q</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Formula (5) shows that in a pipeline with a constant flow rate and a short distance, the deposition amount is the product of the area enclosed by the curve SS ₁ and the curve SS ₂ and the flow rate Q.

2. The short-term deposition status of non-confluent small-diameter strut pipes

The small diameter of the pole is mainly located at the beginning of the drainage pipe, and the change of water quality, water volume and flow rate mainly depends on factors such as regional land use, production technology, living habits and rainfall. Therefore, within the allowable range of error, SS, flow Q and flow velocity v can be regarded as piecewise functions, so formula (3) can be simplified as:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

In the formula, n is the number of monitoring time periods, Q _i is the average flow rate in the pipeline in the i-th section, SS _{1, i} (t _i ) is the SS fitting function of one point in the inspection well in the i-th section, and SS _{2, i} (t _i ) is the SS fitting function of the inspection well 2 and 2 points in the i-th section, l is the distance between the inspection well 1 and the inspection well 2 2, V _i is the average flow velocity in the i-th time period, and t _i is the i-th time duration of the segment.

The monitoring methods and experimental instruments involved in the present invention are easy to implement, such as the following examples.

Example 1:

1. Select a qualified 110m long pipe section in the Dongjiao 1st Road section of Xi'an City on the spot, with a pipe diameter of 300mm and no confluence in between. The sediment deposition status of the research time period is 8:00-16:00;

2. Monitor routine indicators such as total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ -N), and chemical oxygen demand (COD) on the water samples taken calculate. Routine indicators are measured by Hach reagent; SS difference is measured by drying and weighing method, and the sedimentation rate of SS is calculated by the following formula:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; v</span>}}$

D——Sedimentation rate (mg/L s)

SS ₁ ——measured value of SS in inspection well 1 (mg/L)

SS ₂ ——measured value of SS at 2 places in inspection well 2 (mg/L)

l——Inspection Well Spacing (m)

v——Instant velocity (m/s)

3. The particle size distribution can be measured by a professional particle size analyzer, and the relationship between the median particle size _D50 is represented, as shown in Figure 3. It can be found that the particle sizes of the suspended matter at the two sampling points at different times are all different. Decrease, the median particle size generally decreases, and the D ₅₀ reduction reaches 23.1% at the beginning, but the effect gradually weakens with the increase of flow rate.

4. Since the water quality, water volume, and flow rate of the water sample in the pipeline roughly change with time, the jump time is about 2 hours, and the change is not significant within a certain period of time, which belongs to special case 2. Therefore, a group of samples is taken every 2 hours from 8:00 to 16:00;

5. Divide the ΔSS function, Q function and V function into sections according to time, as shown in Table 1, and put the functions into formula (6) according to the corresponding sections, and the results are listed in Table 1:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}$

Table 1 Piecewise functions and calculation results

6. From the data analysis in Table 1 and Figure 2 and Figure 4, it can be seen that the sedimentation rate of suspended solids in small pipe diameters is inversely correlated with the flow rate in the pipeline, and the large-sized suspended solids settle in the pipeline preferentially over the small-sized suspended solids , and the deposition effect will decrease with the increase of flow velocity. Except for TN, the concentration of other indicators decreased very little, but at 12:00 when the concentration was high, NH ₄ ⁺ and NO ₃ were significantly degraded, which were 33.4% and 58.6% respectively, which was mainly caused by the sedimentation of suspended solids; at other times It may be that its degradation mainly depends on other processes such as biological decomposition or physical chemistry, so the effect is not obvious; the concentration of TN is significantly reduced, and the average degradation rate is 0.034mg/L·s, reaching 34.6%, which proves that the sediment N content is higher. It can also be seen that the sedimentation effect of suspended solids is more obvious when the concentration is higher. And its deposition from 6 o'clock to 16 o'clock is 34814.42 mg.

Example 2:

1. The qualified 80m-long pipeline in the first section of Xi'an City, with a pipe diameter of 300mm, has no confluence during the period, and regularly investigates the water quality, quantity and sediment. The research time is from 0:00 to 10:00, and the results are listed in Table 2;

2. Monitor routine indicators such as total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH ₄ ⁺ -N), nitrate nitrogen (NO ₃ -N), and chemical oxygen demand (COD) on the water samples taken calculated and listed in Table 3. Routine indicators are measured by Hach reagent; SS difference is measured by drying and weighing method, and the sedimentation rate of SS is calculated by the following formula:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; SS</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; v</span>}}$

D——Sedimentation rate (mg/L s)

SS ₁ ——measured value of SS in inspection well 1 (mg/L)

SS ₂ ——measured value of SS at 2 places in inspection well 2 (mg/L)

l——Inspection Well Spacing (m)

v——Instant velocity (m/s)

3. The particle size distribution can be measured by a professional particle size analyzer, and the relationship between the median particle size _D50 is represented, as shown in Figure 5. It can be found that the particle sizes of the suspended matter at the two sampling points at different times are all different. Decrease, the median particle size generally decreased, and the D ₅₀ decrease reached a minimum of 23% at 12 o'clock in the morning, but the effect gradually weakened with the increase of flow rate.

4. The sampling research found that the flow rate, flow rate and SS in the pipeline belong to continuous flow and the changes are relatively significant, so it is necessary to fit a fitting curve simulation curve. A group of samples is taken every 2 hours, and its indicators are shown in Table 2. The fitting equation of each curve is:

SS ₁ (t)＝0.1706t ⁵ -4.3542t ⁴ +37.901t ³ -124.21t ² +101.92t+130

R ² =1.000

SS ₂ (t)＝0.1549t ⁵ -3.8177t ⁴ +31.922t ³ -99.229t ² +68.333t+120

R ² =1.000

Q(t)＝0.1707t ⁴ +2.9172t ³ -12.258t ² +3.9303t+48.622

R ² =1.000

V(t)＝-0.006t ⁴ +0.011t ³ -0.0502t ² +0.0325t+0.248

R ² =0.998

5. Bring the above fitting formula into formula (3), and use the random point-seeking algorithm to carry out the integral operation of formula (3) from 0:00 to 10:00. Combined with the analysis of Table 2, Table 3 and Figure 5, the sedimentation rate of suspended solids in small pipe diameters is inversely correlated with the flow rate in the pipeline, during which suspended solids with large particle diameters settle in the pipeline preferentially over suspended solids with small particle diameters, and the deposition effect will decrease. Decreases with increasing flow velocity. Except for COD, the concentration of other indicators decreased very little, which proved that the content of COD in the sediment was high. It can also be seen that the sedimentation effect of suspended solids is more obvious when the concentration is higher. The SS analysis shows that the deposition amount from 6 o'clock to 16 o'clock is 33769.35 mg.

Table 2 Monitoring data

Table 3 Water quality parameters (mg/L)

Claims (6)

1. a kind of monitoring and qualitative quantitative analysis method to sediment in the small-diameter sewage pipeline, it is characterized in that, select the pipeline (3) of short distance, no confluence and diversion, from the inspection well one (3) of connecting pipeline (3) 1) Take samples regularly, and measure the flow and velocity of the water flow at the same time using a flowmeter, and obtain the time for the water flow to reach the inspection well 2 (2) located downstream of the inspection well 1 (1) according to the distance and flow velocity, and check the flow at this time. Well two (2) sampling; then according to the formula Calculate the sedimentation rate of SS during the period, where D is the sedimentation rate, unit mg/L s; SS ₁ is the measured value of SS at inspection well one (1), unit mg/L; SS ₂ is inspection well two (2) SS measured value, unit mg/L; l is the distance between inspection well one (1) and inspection well two (2), unit m; v is the water flow between inspection well one (1) and inspection well two (2) The flow velocity between them, unit m/s; According to the sedimentation rate, the condition of the sediment is obtained, and the conventional index and particle size distribution of the water flow are measured at the same time, so as to qualitatively analyze and judge the sediment in the pipeline, and according to the formula M _deposition = (SS ₁ -SS ₂ )·Q·Δt is obtained from the sediment accumulation M _deposition between inspection well one (1) and inspection well two (2), where Q is the average flow rate in the pipeline, and Δt is the flow rate from inspection well one (1) ) and inspection well two (2) sampling interval. 2. The method for monitoring and qualitative and quantitative analysis of sediments in small-diameter sewage pipes according to claim 1, wherein the conventional indicators include total phosphorus TP, total nitrogen TN, ammonia nitrogen NH ₄ ⁺ -N, Nitrate nitrogen NO ₃ -N and chemical oxygen demand COD are measured by Hach reagent or national standard method. 3. The monitoring and qualitative and quantitative analysis method for deposits in small-diameter sewage pipes according to claim 1, wherein the SS is measured by drying and weighing, and the particle size distribution utilizes particle size Analyzer or sieve method for determination. 4. according to claim 1 to the monitoring and the qualitative and quantitative analysis method of sediment in the small-diameter sewer pipeline, it is characterized in that, described M _deposition calculation formula utilizes the calculation equation after calculus solution to be: Among them, t ₀ is the initial test time, t is the end time, Q(t) is the flow fitting function, SS ₁ (t) is the SS fitting function of inspection well one (1) point, SS ₂ (t) is the inspection well The SS fitting function of the two (2) points, V(t) is the velocity fitting function, and l is the distance from the inspection well one (1) point to the inspection well two (2) point, when the water quality and quantity in the pipeline change constant, That is, the change of the deposition amount is the product of the area enclosed by the curve _SS1 and the curve _SS2 and Q. 5. The monitoring and qualitative and quantitative analysis method for deposits in small diameter sewage pipes according to claim 1, characterized in that, the calculation formula for the sediment content in the non-converging small pipe diameter support rod drainage pipe section is: Among them, n is the number of monitoring time periods, Q _i is the average flow rate in the pipeline in the i-th section, SS _{1, i} (t _i ) is the SS fitting function of one (1) point of the inspection well in the i-th section, SS _{2, i} ( t _i ) is the SS fitting function of inspection well 2 (2) in the i-th section, l is the distance between inspection well 1 (1) and inspection well 2 (2), V _i is the average flow velocity in the i-th time period , t _i is the duration of the i-th time period. 6. The method for monitoring and qualitative and quantitative analysis of sediments in small-diameter sewage pipes according to claim 1, characterized in that, the diameter of the pipeline (3) is below 300mm and there is no diversion and confluence.