OPERATING CONDITION DIAGNOSIS SYSTEM FOR ACTIVATED SLUDGE PROCESSES BASED ON MICROORGANISM IMAGE INFORMATION

ABSTRACT In this paper, an operating condition diagnosis system, based on image information, is proposed as a means for controlling activated sludge processes. Experimental investigations, in which the organic load is controlled for a laboratory scale experimental apparatus, are carried out under several conditions. The relationships between SVI (Sludge Volume Index), the length of the filamentous microorganisms, the floc size and volume are investigated using previously proposed image processing techniques. A new index “the bulking index”, B I, using image information, is expressed as a function of these variables: Download full-size image where B I: Bulking index R: Floc size ( μ m) F: Filamentous microorganisms length (m/mg-MLSS) V: Floc volume (ml) The proposed index B I is based on a physical discussion of Robinson's formula which represents the relationship between sludge settling velocity, floc size, density difference and viscosity of mixed liquor. Experimental results show that the index is suited to predictions of the outbreak of filamentous bulking. In addition, the floc volume V, measured by image processing, is presented as an alternative MLSS sensor, since there is a clear relationship between V and MLSS values as observed experimentally.