Abstract: In the process of continuous development of industrial production, a large amount of industrial wastewater will be produced. If these wastewaters are not effectively treated, they will cause serious pollution to the ecological environment. When wastewater treatment is carried out, we must keep abreast of the water quality of the wastewater to ensure the effectiveness of the wastewater treatment measures. Therefore, automated on-line instrumentation is required to detect the water quality. In the application of automated online instrumentation such as electromagnetic flowmeters, it is necessary to understand the types of instrumentation used and the characteristics of the parameters in order to properly manage and technically modify them. This article will explore the application of automated online instrumentation in wastewater treatment.
In-line instrumentation plays an important role in the processing of industrial wastewater. In the application of these online monitoring instruments, the use of more advanced science and technology enables the online testing instruments to achieve automatic operation, greatly reducing the manpower and material resources consumed by the online testing work, and realizing the timely adjustment of the wastewater treatment process. Therefore, we must master the application characteristics of various instruments in online testing, and make rational use of these features in practical applications, improve the application efficiency of automated online instrumentation, promote the improvement of wastewater treatment efficiency, and make ecological environmental protection work. The corresponding contribution.
Automated online instrumentation such as electromagnetic flowmeters is an important part of industrial wastewater treatment systems. In general, the mechanism for automating online instrumentation is mainly composed of three parts: sensor, transmitter and display. In these three parts, the role of the sensor is mainly to detect the analog quantity to be detected by means of signal detection, and the role of the transmitter is mainly to convert the analog signal measured by the sensor into a current line number, and These signals are sent to the programmable controller (PLC), which is used to display the results of all online tests for easy reading by the staff. In the actual application process, the three parts are the organic whole that are closely combined, and they belong to the complementary relationship. No matter which part is missing, the online detection function cannot be realized smoothly. The automated online instrumentation has the characteristics of simple operation, accurate measurement and clear display. It has been widely used in the treatment of industrial wastewater and is an important part of the automatic control system for wastewater treatment.
2.1 Overview of wastewater treatment process
Under normal circumstances, the wastewater treatment process is mainly divided into the following three stages:
First, the first stage of processing. The treatment at this stage is to apply physical treatment to filter out solid contaminants in the wastewater. The treated wastewater can remove about 30% of BOD substances, but it cannot meet the emission standards and can only be used as a pretreatment stage in the secondary treatment stage.
Second, the secondary processing stage. This stage of treatment can remove BOD and COD substances in colloid or dissolved state in wastewater, and the removal rate can be as high as 90% or more to ensure that organic pollutants meet emission standards.
Third, the three-stage processing stage. This stage of treatment can remove organic matter that is difficult to degrade in wastewater and can cause soluble inorganic substances such as nitrogen and phosphorus in water. The treatment methods applied mainly include coagulation sedimentation method, biological nitrogen and phosphorus removal method, ion exchange method, activated carbon adsorption method and sand filtration method.
2.2 Wastewater treatment specific operation process
The specific operation process of wastewater treatment is as follows: First, the operation of the first-stage treatment stage is to first filter the wastewater with a coarse grid, and then lift the wastewater with a lift pump, pass through a sand filter or a grid, and then inject it into the grit chamber. The sand is separated from the water in the grit chamber and flows into the initial sedimentation tank. Secondly, the operation of the secondary treatment stage is to inject the wastewater from the initial sedimentation tank into the biological treatment equipment, where the biological treatment can be carried out by the biofilm method or the activated sludge method, wherein the reactor used in the activated sludge method includes an oxidation ditch. The reactor used in the biofilm process includes a biological turntable, a biological filter, and a biological fluidized bed. After the water flows out of the biological treatment equipment, it flows into the secondary sedimentation tank, and the precipitated water can be transferred to the next treatment stage after being disinfected. Finally, the operation of the tertiary treatment stage is the final treatment of water using a coagulation sedimentation method, an ion exchange method, an activated carbon adsorption method, and a sand filtration method.
3.1 Application of ultrasonic liquid level difference meter
In the wastewater treatment system, the ultrasonic liquid level difference meter should be installed in the coarse grid and the fine grid. The meter can be used to calculate the liquid level difference before and after the wastewater passes through the grid to reflect the grid blocking rate. At the same time, the data is transferred to the programmable controller for further analysis. If the detected liquid level difference is higher than the specified value, the grid should be properly treated to completely remove the garbage inside the grid to ensure that the wastewater can pass normally and reduce the wear rate of the equipment.
3.2 Application of ultrasonic level gauge
In order to realize the automatic control of the inlet pump, we can install the ultrasonic level gauge at the inlet pump well, which can accurately detect the water level in the pump well and transmit the test data to the programmable controller and the host computer in time. In the system, it is systematically analyzed and calculated, and then the corresponding program is reasonably controlled according to the analysis result, and the automatic operation control of the pump is raised. In this way, the lift pump can be adjusted according to the amount of water in the waste water to reduce the fatigue of the lift pump.
3.3 Application of ultrasonic flowmeter
Water flow is a very important technical parameter in the management of wastewater treatment. Being able to accurately control and control the flow of water is not only a very important application of the control of process parameters, but also a key factor in improving the ability to withstand hydraulic load shocks. In the traditional flow detection, we generally use venturi flow slots or slabs and other detection equipment, but these detection methods have the defects that the detection results can not be displayed in real time. However, the use of ultrasonic flowmeters to detect water flow can fundamentally solve the protocol problem, improve the real-time display of water flow detection results, accurately grasp the flow rate of wastewater treatment, and provide a reliable basis for wastewater treatment management.
3.4 Application of Dissolved Oxygen Meter
In the automatic online measuring instrument, the dissolved oxygen meter is mainly installed in the aeration tank, and is used for detecting the dissolved oxygen in the pool, and transmitting the detected data information to the programmable controller and the upper computer, and performing the same. Systematic analysis and calculation. The system will start or stop the aeration and disc rotation operation according to the analysis result of dissolved oxygen, which not only can optimize the biochemical capacity of the flora, but also can save energy consumption and protect the processing equipment to a certain extent.
3.5 Application of sludge concentration meter
Sludge concentration is an important parameter indicator in wastewater treatment. For the detection of sludge concentration, the traditional method is realized by means of experimental detection. However, this method has a large gap in timeliness and accuracy, and it is impossible to realize the return sludge and residual pollution. The amount of mud is adjusted in time. In order to solve such problems, we installed the sludge concentration meter in the aeration tank, which can detect the sludge concentration at any time and improve the accuracy of the detection. It can not only realize the timely return of sludge and excess sludge. Process adjustments and can effectively reduce the workload of laboratory staff.
3.6 Application of electromagnetic flowmeter
In order to improve the detection efficiency of the flow rate of the return sludge and the excess sludge, the electromagnetic flowmeter can be installed in the return sludge pipe and the excess sludge pipe to realize automatic detection of the two flows, and the installation is simple and the maintenance is convenient. After applying the electromagnetic flowmeter, the staff can judge the working state of the return sludge pump and the surplus sludge pump according to the display result of the meter, and effectively solve the problem that the submersible pump cannot be accurately determined.
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When managing automated online instrumentation in a wastewater treatment system, the following points need to be noted:
4.1 Pay attention to the cleaning of the online instrument
On-line instrumentation must be cleaned regularly by a person to ensure that the instrument is clean and improve the accuracy of data collection, especially in direct contact with sewage, including dissolved oxygen meters and sludge concentration meters. During the cleaning process, pay attention to the use of soft tools to avoid damage to the instrument.
4.2 Regular calibration of online instrumentation
In the long-term operation process, online detection instruments may have detection errors. In order to ensure the accuracy of their detection results, these instruments must be calibrated regularly. At the same time, the laboratory staff needs to analyze the corresponding test items and compare them with the on-site instrument test results to calibrate the instruments in time.
All in all, in the process of wastewater treatment, automated on-line instrumentation plays an important role, and the rational application of these instruments is beneficial to the effective control of the wastewater treatment process.