The relationships between bacterial storage products, density, and settling characteristics were determined in a laboratory-scale sequencing batch reactor (SBR) enhanced biological phosphorus removal (EBPR) system. Both long-term and single anaerobic-aerobic cycle variations in these properties were studied. Increased polyphosphate (PP) content of the biomass during long-term operation resulted in improved sludge volume index (SVI) values. End-aerobic phase (after phosphate (P) uptake) values were consistently lower than end-anaerobic phase (after P release) values. Neither filamentous nor slime bulking were evident by microscopic observations. Biomass density increased at a rate of 1.2 mg/L per each 1% increase in biomass P content. End-aerobic phase samples had an average 25% higher buoyant density than end-anaerobic phase samples, which was attributed to aerobic P uptake. Biomass density was negatively correlated with SVI values, and SVI values increased sharply at low biomass density. A mathematical model developed by Mas et al. (1985) was modified to predict total cell density based on literature values of PP, glycogen (GLY), and poly-b-hydroxybutyrate (PHB) densities. Model predictions were in good agreement with experimental results, although improved measurement of PP density is required to improve model predictions.
Microbial storage products, biomass density, and settling properties of enhanced biological phosphorus removal activated sludge
A. J. Schuler, D. Jenkins, P. Ronen; Microbial storage products, biomass density, and settling properties of enhanced biological phosphorus removal activated sludge. Water Sci Technol 1 January 2001; 43 (1): 173–180. doi: https://doi.org/10.2166/wst.2001.0042
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