This paper presents a new method for evaluation of microbial flocs coagulation based on the fractal dimension and image processing. Microorganisms are used widely in sewage disposal plants and wastewater treatment facilities. Plant operators evaluate the state of coagulation from their experience on the basis of complicated shapes observed in the coagulation process. However, it is difficult to recognize and evaluate the shapes of the coagulation quantitatively. In order to evaluate the shapes, we employ a technique based on the fractal dimension which has been applied in the analysis of irregular and complex shapes. We captured the image of coagulation with a CCD camera and measured the fractal dimension of the shapes in the image. The standard deviation of the fractal dimention was then analyzed. The result shows that the fractal dimension can quantitatively express the state of the coagulation and that the coagulation process can be evaluated by the standard deviation.
