Variations of morphology of activated sludge flocs studied at full-scale wastewater treatment plants

Abstract

Digital image analysis has been intensively developed over the last two decades including its application to describe morphology of activated sludge flocs. However, only few studies concerned the variation of flocs morphology with respect to the operational conditions, particularly oxido-reductive conditions, in a full-scale wastewater treatment plant (WWTP). In this work, morphology of activated sludge flocs was monitored over one year in two different full-scale WWTPs. The main aim of this study was to find the relationship between the operational parameters and morphology of sludge flocs. Simultaneously, the variations in floc size along activated sludge chamber were studied with respect to the oxido-reductive conditions. It was found that the sludge loading rate was one of the most important operational parameters influencing floc size. It was estimated that its values higher than 0.1 kg BOD5 kg TS(-1) d(-1) contributed to the decrease in floc size. Also, the oxido-reductive conditions influenced the floc size. It was statistically proved that flocs from the anaerobic zone were usually smaller than flocs from the anoxic or aerobic zones. Distribution of floc size in a full-scale WWTP usually could be described by a log-normal model.

Study on activated sludge flocs morphology and composition in a full-scale wastewater treatment plant in Poland

“…In the winter campaign, the differences in flocs diameters between anaerobic and aerobic zones were not statistically relevant ( p-value equal to 0.104), in contrast to the summer campaign ( p-value equal to 0.00472). These findings are in agreement with the previous observations in the long-term study [17]. The values of standard deviation of the mean diameter shown in Fig.…”

“…The object of the study was the Wastewater Treatment Plant in Zgierz (WWTP Zgierz) treating municipal wastewater. The biological step consisted of one five-zone bioreactor and secondary clarifier run in the Phoredox process configuration [17]. The total volumes of each zone were as follows: 857.5 m 3 -anaerobic zone, 3536 m 3 -first anoxic zone, 15 850 m 3 -first aerobic zone, 3118 m 3 -second anoxic zone, and 795 m 3 -second aerobic zone.…”

“…Procedure No. 1 including the definitions of morphological parameters measured has been presented elsewhere [17].…”

Illumination Compensated Segmentation of Microscopic Images of Activated Sludge Flocs

“…It is because quantification and morphology of flocs are used to characterize the abnormal conditions in activated sludge process [4][5][6][7][8]. As show in the table III, the proposed algorithm performed better than all others in terms of quantification too.…”

“…The activated sludge plants are conventionally monitored by physicochemical tests such as sludge volume index (SVI) and chemical oxygen demand (COD). Image processing and analysis is a time-efficient alternative to the physico-chemical tests to monitor the activated sludge wastewater treatment plant [1][2][3][4]. In the recent years, the application of image processing and analysis to the activated sludge wastewater treatment has been extensively researched and reported [3][4][5].…”