Application of in-situ micro laser transmission on real-time monitoring of flocculation process

A low-cost in-situ micro laser transmission (IMLT) analysis system for particle size monitoring based on the principle of laser transmission extinction was developed to monitor the flocculation process. In this study, the IMLT system was used to obtain the voltage generated with the changes of flocculant dosage and floc sizes in different flocculation stages. A typical machine learning model, convolution neural network (CNN) method was built to manage the flocculant dosage, detection voltage and floc size to improve the accuracy of the correlation between the them. Results of IMLT revealed that the particle size of flocs was inversely proportional to the voltage, and a larger final voltage R value indicated better effects of flocculation and sedimentation. The correlation between the particle size obtained by CNN training and measured particle size was 42.4 % and 30.5 % higher than that without training at low and high concentrations, respectively. IMLT is effective in reflecting the floc sedimentation, stability and dynamic influence of the coagulant aid on flocculation system.