ABSTRACT
This chapter determines the influence of full-scale activated sludge treatment plant operational conditions on solids settling characteristics. The settleability of activated sludge solids are a central consideration in treatment system clarifier design and operation. Empirical settling tests, such as the sludge volume index (SVI), have long formed the basis of judgment in operational management; however, research has indicated that this empirically-based approach can lead to system failure. An alternative management method known as the mass-flux state-point approach has been developed by numerous researchers. Preliminary studies indicated that solids settling characteristics varied over relatively short time frames. To analyze the fluctuations, gravity flux was monitored over 24-to 72-hour periods during the 20-month study. The chapter discusses the three parameter types: settling parameters relating solids separation to slurry concentration; flux parameters quantifying both solids settleability and system operating conditions; and operational parameters traditionally used to describe the treatment facilities operating state and performance.
