Measurement Of The Pollutant Particles In Water By The Transmission Fluctuation Spectrometry With Correlation

In recent years, whether cyanobacteria in Taihu Lake or drinking excessiveimpurities are causing people to play close attentions to water treatment. Theexisting multi-parameter water detectors can simultaneously measure pH, ORP(redox potential), TDS (the contents of total dissolved solids), dissolved oxygen,temperature, conductivity, salinity and so on, but don’t involve the measurementsof particle size and particle concentration, which are both the very importantparameters in the field of water quality inspection. In the process of the waterpollution treatment, an important part is the real-time and on-line measurement forthe water pollutant particles, which will provide corresponding parameters forwater treatment. Up to now, there are many methods of the water qualityinspection in the domestic and international literature, in which the samplingmethod are utilized mainly and the real-time and online detection methods areused rarely.The transmission fluctuation spectrometry with correlation is a new opticalmethod developed in recent years, in which both the particle size distribution andparticle concentration can be measured simultaneously. Due to the simple opticalsetup, the transmission fluctuation spectrometry with correlation can be used asreal-time, online technique for measuring the pollutant particles in water. Twobeams of light produced by a laser through optical beam splitter irradiate thepollutant particles in water. Due to the absorption and the scattering of thepollutant particles in water, the transmitted lights produce attenuations and showfluctuating characteristics. The transmission fluctuation spectrum may be obtainedwith correlation techniques. One of correlation techniques is the spatialcorrelation (transmission fluctuation spectrometry with spatial correlation,TFS-SC), in which two parallel beams with a separation between each other areemployed and the expectancy of the transmission product (ETP) is measured as afunction of the beam separation, which includes the information on the flowvelocity. This velocity is regarded as known parameter in the transmissionfluctuation spectrometry with temporal correlation or auto-correlation (shortlyTFS-TC or TFS-AC). The particle size distributions and concentrations are extracted from the experimental data with the modified Chahine iterations. Sixparts will be given for the transmission fluctuation spectrometry with thecorrelation.In the first part of this thesis, the background of particle measurements, theparticle in water, and the development of the transmission fluctuationspectrometry are introduced.In the second part, concepts and knowledges on the transmission fluctuationspectrometry with correlation are introduced, which are the basis of the latterdepictions.The third to sixth chapters are the core parts of this thesis. In the third chapter, onthe basis of the transmission fluctuation spectrometry with spatial correlation, thefeatures of TFS-SC and TFS-AC, the theoretical model, the theoretical derivationand the theoretical calculation curves are given. And the measurement principle ofthe transmission fluctuation spectrometry with correlation is presented. As thebeam diameter is20μm, the particle size is more than1μm, just meeting therequirement for measuring the pollutant particles in water.On the basis of the third chapter, the numerical simulatuins on transmissionfluctuation spectrometry with correlation are given in the fourth chapter. Firstly,the monolayer particle system is discussed. The numerical simulation on themonolayer is performed only with the monolayer structure and without theparticle overlapping. Alternatively, this may be simulated either by assuming alarge number of layers, each layer containing very few particles only, or byassuming a single, dense monolayer containing non-interacting particles, wherebyparticles are allowed to interpenetrate with each other. The dense monolayercontaining N non-interacting particles is equivalent to a3-dimensional particlesuspension containing N layers, each layer containing one particle only. At the last,the numerical simulatuins of3-dimensional particle system is given (i.e. theparticle overlapping and the monolayer structure exsit simultaneously).The fifth chapter presents the measurment results of the pollution particles inwater. The experimental device design is introduced briefly and the samples arethe soybean milk powders, the lotus root powders and three kinds of pearlpowders dispersed in water. The flow velocity of the particle system is obtainedby the transmission fluctuation spectrometry with spatial correlation, which will be taken as a known parameter in the TFS-AC. Finally, the transition functioncurves based on the soybean milk powder, the lotus root powder and the pearlpowders in water are obtained.In the sixth chapter, inversion algorithms are introduced. Considering thecharacteristics of this subject, the particle size distributions and concentrations areextracted with the modified Chahine iterations from the experimental data.Reasonable results are obtained for particles in the range of microns and at lowconcentrations.