Mixed sampling method for intermittently discharged wastewater sample based on flow threshold

Abstract

The invention discloses a mixed sampling method for a wastewater sample intermittently discharged by sewage based on a flow threshold. The method comprises the following steps: establishing a sampling system, and monitoring the real-time discharge flow of target wastewater by a flow monitoring unit; configuring sampling parameters, triggering sampling according to the minimum flow threshold value of field wastewater discharged every time, starting sampling when flow exists, and not starting sampling when flow does not exist; the effective sampling times are configured according to the total wastewater discharge amount per hour; after the first flow is successfully triggered, triggering a sampling unit according to a minimum flow threshold value to collect wastewater intermittently discharged from a target wastewater discharge port in a short time; the sampling unit conveys a water sample to be detected to the data analysis unit for detection, and the data control unit uploads monitoring data to the monitoring center platform. According to the method, flow triggering and timing sampling supplement are combined, it is ensured that a water sample can be obtained in the sewage discharge period, the water sample is more representative, it is avoided that discharge is not monitored, and tracing of monitoring data in the later period is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of water pollution online monitoring, and in particular to a mixed sampling method for wastewater samples based on intermittent discharge of sewage with a flow threshold. Background Art

[0002] Water pollution is monitored online through wastewater flow monitoring, wastewater sample collection, wastewater sample analysis, and analysis data statistics and uploading. Figure 1 The following is the composition of the conventional water pollution online monitoring system. Cr , NH3-N, etc.) Acceptance Technical Specifications (HJ 354-2019) and Online Monitoring System for Water Pollution Sources (COD Cr According to the relevant requirements of the Technical Specifications for the Operation of Wastewater Treatment Plants (HJ 355-2019), the wastewater sampling has been changed from the original instantaneous sampling to mixed sampling. Usually, the wastewater mixed sampling is completed by the automatic water quality sampling equipment, which generally consists of two barrels A and B, which are used alternately during sampling.

[0003] In actual wastewater discharge, there are two types of discharge: continuous and intermittent. According to the relevant requirements of the above technical specifications, mixed samples need to be collected for monitoring for both types of discharge. For continuous discharge conditions, time-proportional or flow-proportional sampling methods can meet the requirements of mixed sampling.

[0004] However, for intermittent emission conditions, since the emission is discontinuous, the collection of mixed samples by single-time proportional sampling will cause the sampling equipment to idle multiple times ineffectively, causing great loss to the sampling equipment and reducing its service life. Figure 2 As shown in the figure, the single traffic trigger mode sampling has the following problems: (1) The samples lack representativeness. The sampling volume of A / B barrels is generally 3 to 4 liters, and it takes about 10 minutes to fill the sample. For example, barrel A starts sampling first, and after barrel A is full, it supplies samples to the analyzer. Then barrel B starts sampling, and it takes about 10 minutes to fill the sample. After the longest analysis time of the analyzer is over, barrel B starts to supply samples. At this time, barrel A / B only collects water samples from the first 20 minutes of the hour, and the analyzer reports two sets of analysis data, which are actually water sample analysis data from the first 20 minutes of the same hour, which lacks representativeness; (2) Discharge without monitoring. In the above example, bucket A / B only collected water samples for the first 20 minutes of the hour, and did not cover the water samples for the last 40 minutes, resulting in the problem of wastewater discharge without monitoring. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a mixed sampling method for wastewater samples under intermittent sewage discharge based on flow threshold. This method overcomes the defects of traditional wastewater sampling methods under intermittent sewage discharge conditions, combines flow triggering with timed sampling supplement, and ensures that water samples can be obtained during the sewage discharge period, making the water samples more representative, avoiding discharge without monitoring, and facilitating the traceability of subsequent monitoring data.

[0006] In order to solve the above technical problems, the mixed sampling method of wastewater samples of intermittent discharge of sewage based on flow threshold sewage of the present invention comprises the following steps: Step 1: Establish a sampling system, including a flow monitoring unit, a sampling unit, a data control unit and a data analysis unit, and establish a logical control relationship between them. The data control unit coordinates the operation of the sewage online monitoring system, collects water samples, stores data, displays monitoring data and operation logs, and uploads monitoring data to the monitoring center platform; Step 2: The flow monitoring unit monitors the real-time discharge flow of the target wastewater, obtains the flow data, and uploads it to the data control unit; Step 3: Configure sampling parameters. Trigger sampling by flow rate. Trigger sampling based on the minimum flow rate threshold for each on-site wastewater discharge. Start with flow rate trigger. Read the flow signal once at the interval set time according to the duration of each on-site wastewater discharge. Start sampling when there is flow rate, and do not start sampling when there is no flow rate. The effective sampling times are configured according to the total amount of wastewater discharged per hour, and must meet the water volume required for each analysis. Step 4: After the first flow rate is triggered successfully, the data control unit reads the flow rate signal, triggers the sampling unit according to the minimum flow rate threshold to collect the wastewater discharged intermittently from the target wastewater discharge port, and the data control unit triggers the sampling unit to supply samples; Step 5: The sampling unit transports the water sample to be tested to the data analysis unit for testing through the peristaltic pump and the corresponding pipeline, and uploads the monitoring data to the monitoring center platform through the data control unit.

[0007] Furthermore, in the step three, sampling is triggered when the wastewater discharge flow rate is greater than 0.11 cubic meters per second; and the interval for reading the flow signal is set to 15 minutes.

[0008] Furthermore, in the step three, the number of effective sampling times is greater than 1 time per hour. Since the present invention samples the above technical scheme based on the mixed sampling method of wastewater samples discharged intermittently by sewage based on flow threshold, that is, the method establishes a sampling system, the flow monitoring unit monitors the real-time discharge flow of the target wastewater, obtains flow data, and uploads it to the data control unit; the sampling parameter configuration triggers sampling according to the minimum flow threshold of each discharge of on-site wastewater, and starts with flow triggering, reads the flow signal once at an interval setting time, starts sampling with flow, and does not start sampling without flow; the effective sampling times are configured according to the total amount of wastewater discharged per hour, and the amount of water required for each analysis must be met; after the first flow trigger is successful, the sampling unit is triggered by the minimum flow threshold to collect the wastewater discharged intermittently in the target wastewater discharge port for a short time, and the sampling unit is triggered by the data control unit to supply samples; the sampling unit transports the water sample to be tested to the data analysis unit for detection, and uploads the monitoring data to the monitoring center platform through the data control unit. This method overcomes the defects of the wastewater sampling method under the traditional sewage intermittent discharge working condition, combines flow triggering with timed sampling supplementation, ensures that water samples can be obtained during the sewage discharge period, makes the water samples more representative, avoids discharge without monitoring, and facilitates the traceability of monitoring data in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 This is the principle block diagram of the conventional water pollution online monitoring system; Figure 2 It is a schematic diagram of the corresponding relationship between sampling action and sampling time in single flow trigger mode; Figure 3 This is the principle block diagram of the sampling system in this hybrid sampling method; Figure 4 Schematic diagram of the sampling time and sampling action effect of this method. DETAILED DESCRIPTION

[0010] Implementation example Figure 3 As shown, the mixed sampling method of wastewater samples of intermittent discharge of sewage based on flow threshold sewage of the present invention comprises the following steps: Step 1: Establish a sampling system, including a flow monitoring unit, a sampling unit, a data control unit and a data analysis unit, and establish a logical control relationship between them. The data control unit coordinates the operation of the sewage online monitoring system, collects water samples, stores data, displays monitoring data and operation logs, and uploads monitoring data to the monitoring center platform; Step 2: The flow monitoring unit monitors the real-time discharge flow of the target wastewater, obtains the flow data, and uploads it to the data control unit; Step 3: Configure sampling parameters. Trigger sampling by flow rate. Trigger sampling based on the minimum flow rate threshold for each on-site wastewater discharge. Start with flow rate trigger. Read the flow signal once at the interval set time according to the duration of each on-site wastewater discharge. Start sampling when there is flow rate, and do not start sampling when there is no flow rate. The effective sampling times are configured according to the total amount of wastewater discharged per hour, and must meet the water volume required for each analysis. Step 4: After the first flow rate is triggered successfully, the data control unit reads the flow rate signal, triggers the sampling unit according to the minimum flow rate threshold to collect the wastewater discharged intermittently from the target wastewater discharge port, and the data control unit triggers the sampling unit to supply samples; Step 5: The sampling unit transports the water sample to be tested to the data analysis unit for testing through the peristaltic pump and the corresponding pipeline, and uploads the monitoring data to the monitoring center platform through the data control unit.

[0011] Preferably, in step three, sampling is triggered when the wastewater discharge flow rate is >0.11 cubic meters per second, and the trigger limit can be configured according to the minimum flow rate of each wastewater discharge on site; the interval setting time for reading the flow signal is 15 minutes, and the interval setting time can be configured according to the duration of each drainage on site. If there are special requirements, the reading frequency of the flow signal can be encrypted.

[0012] Preferably, the effective sampling times in step 3 is greater than 1 time per hour. The effective sampling times can be configured according to the total amount of wastewater discharged per hour.

[0013] like Figure 4 As shown in the figure, under the condition of intermittent wastewater discharge, the sampling is triggered by the minimum flow threshold control, and bucket A is sampled every 15 minutes, and bucket A supplies the sample. During this period, bucket B waits for sampling; after bucket A finishes sampling, bucket B continues sampling. Thus, the whole process of intermittent wastewater discharge is covered.

[0014] The sampling start time of this method is more accurate, and the wastewater monitoring data is more representative. During the intermittent discharge of wastewater, mixed sampling can be achieved to ensure that the number of monitoring data is not less than the number of hours of wastewater discharge, which greatly avoids the phenomenon of discharge without monitoring. At the same time, it reduces the loss of core components such as the sampling system, sampling valve, and peristaltic pump, thereby achieving system energy saving and extending the service life of the sampling system.

Claims

1. A mixed sampling method for wastewater samples based on intermittent discharge of sewage with flow threshold, characterized in that The steps include: Step 1: Establish a sampling system, including a flow monitoring unit, a sampling unit, a data control unit and a data analysis unit, and establish a logical control relationship between them. The data control unit coordinates the operation of the sewage online monitoring system, collects water samples, stores data, displays monitoring data and operation logs, and uploads monitoring data to the monitoring center platform; Step 2: The flow monitoring unit monitors the real-time discharge flow of the target wastewater, obtains the flow data, and uploads it to the data control unit; Step 3: Configure sampling parameters. Trigger sampling by flow rate. Trigger sampling according to the minimum flow rate threshold for each on-site wastewater discharge. Start with flow rate trigger. Read the flow signal once at the interval set time according to the duration of each on-site wastewater discharge. Start sampling when there is flow rate, and do not start sampling when there is no flow rate. The effective sampling times are configured according to the total wastewater discharge per hour and must meet the water volume required for each analysis; Step 4: After the first flow rate is triggered successfully, the data control unit reads the flow rate signal, triggers the sampling unit according to the minimum flow rate threshold to collect the wastewater discharged intermittently from the target wastewater discharge port, and the data control unit triggers the sampling unit to supply samples; Step 5: The sampling unit transports the water sample to be tested to the data analysis unit for testing through the peristaltic pump and the corresponding pipeline, and uploads the monitoring data to the monitoring center platform through the data control unit.

2. The mixed sampling method for wastewater samples of intermittent discharge of sewage based on flow threshold according to claim 1 is characterized by: In the step three, sampling is triggered when the wastewater discharge flow rate is greater than 0.11 cubic meters per second; and the interval for reading the flow signal is set to 15 minutes.

3. The mixed sampling method for wastewater samples based on intermittent discharge of sewage with flow threshold according to claim 1 is characterized in that: In the step 3, the effective sampling times are greater than 1 time per hour.

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