Settling Velocity Measurement Of Sewage Treatment Based On Image Processing Technology

With the rapid development of social and industrial technology, the consumption of water is gradually increasing and causes the shortage of water resources, the human production activity also causes a lot of water pollution. Therefore, in order to protect the ecological environment and to make the sewage recycling, whatever it is industrial sewage, drinking water and wastewater, it should be processed to discharge standard, then just can be discharged or used. Thereupon, wastewater treatment technology causes the attention of many researchers. In many sewage treatment methods, flocculation settlement method is the treatment method which is the most widely used and lowest cost. By right of its simple accurate and high separating efficiency, flocculation settlement method becomes the important method for solid-liquid separation of particles that is not easy sedimentation in sewage treatment industry. At present, flocculation technology is an economic, simple and convenient sewage treatment technology to improve the efficiency of water treatment at home and abroad. If the input quantity is controlled seasonably and the sewage treatment achieves good results, the water quality will be ensured and the consumption of flocculants will be reduced, the cost will be reduced, it is fully staffed. But because of controlling input quantity involves many factors, how to reasonably control the input quantity of flocculants is a very difficult problem, becomes the related subject that domestic and foreign scholars research.Sewage settling velocity can be as evaluation index of flocculants effect, but it also can be used as basis of controlling input quantity of flocculants. In this paper measuring sewage settling velocity is the target, a measurement method based on image processing technology is put forward. In this paper research emphasis are image feature extraction and the analysis of sewage settlement process. First, in this paper pretreatment process of sewage image is simply introduced, the process mainly includes image digital, graying and geometric transformation. Secondly, in this paper image feature extraction method of sewage is mainly studied, the algorithm mainly is Principal Component Analysis and Wavelet Transform. Among them, Principal Component Analysis uses contribution rate of one eigenvalue as characteristics, Wavelet Transform uses brightness value of image as characteristics. Finally, the sewage settling curve should be drawn based on the characteristics, analyzing the curve and determining the completion time of sewage settlement. According to the least squares curve fitting, curve expressions will be determined and obtaining sewage settling velocity. According to experimental results, people can evaluate sedimentation effect of flocculants and control input quantity of flocculants, feasibility of the method is validated, this method has good practicability and good effect.