Design And Research Of Multichannel Online Turbidimeter

As the problem of water pollution becomes more and more serious,people pay more and more attention to the quality of water,and turbidity is one of the most important indicators of water quality.At present,in the field of turbidity testing,most domestic turbidimeter use single-point measurement;compared with foreign products,there are gaps in their measurement range and accuracy;at the same time,in sewage treatment,water quality monitoring,and other application scenarios,the impurities in the water body are not uniformly distributed,so single-point measurement results cannot reflect the overall turbidity of the water body,hence the need for multi-point turbidity measurement.In this paper,a wide-range multi-channel online turbidimeter is designed and developed to solve the problem of large discrepancies between single-point measurement results and the real turbidity of water bodies due to the lack of single-point measurement accuracy and the uneven distribution of impurities in the water bodies.The main research work is as follows:1.On the basis of the clarification of turbidity detection theory,the advantages and disadvantages of common turbidity detection schemes are compared and analysed,and a turbidity detection scheme combining vertical scattering and transmission methods is further proposed.2.According to the requirements of the turbidimeter multi-channel design,the hardware design allows access to multiple sensors to achieve multi-point turbidity measurement;according to the requirements of the testing environment,a current-light intensity double feedback loop is designed to control the light source to reduce its own system error;furthermore,the multi-stage circuits of preamplification,filtering and secondary amplification are optimally designed to reduce the environmental interference in the testing process;finally,in the turbidity detection Finally,a narrow band filter is introduced into the optical path to reduce the wavelength range of the effective detection light while reducing stray light interference.3.The software design of the turbidity detection system was carried out.In order to achieve multi-sensor data acquisition and at the same time reduce system power consumption and cost,this study used low-frequency switching and digital PI feedback to control the light source,and a median average filtering algorithm was designed to filter the turbidity data to reduce the interference of bubbles and impurities.4.The turbidimeter calibration experimental study was carried out,and the corresponding turbidity characterization model was established while determining the applicable range of the two turbidity measurement methods.Finally,experimental tests were conducted on the performance of the turbidimeter,such as stability,interference resistance,and multi-channel consistency.The test results show that the turbidimeter has high detection accuracy(relative measurement error 3.16%)and repeatability(repeatability error 2.08%),good stability of turbidity measurement results under different ambient light and temperature conditions,and good consistency of the designed 4-channel turbidimeter.Compared with the same type of turbidimeter in China,the results of this study can provide an important reference value for the performance improvement of the domestic turbidimeter.