ABSTRACT
The activated biosolids process is a man-made process that mimics the natural self-purification process that takes place in steams. In wastewater treatment, activated biosolids processes are used for both secondary treatment and complete aerobic treatment without primary sedimentation. The basic components of an activated biosolids sewage treatment system include an aeration tank and a secondary basin, settling basin, or clarifier. As with other wastewater treatment unit processes, process control calculations are important tools used by the operator to control and optimize process operations. This chapter reviews many of the most frequently used activated biosolids process calculations. Biosolids age refers to the average number of days a particle of suspended solids remains under aeration. This calculation is sometimes referred to as Gould biosolids age so that it is not confused with similar calculations, such as solids retention time (or mean cell residence time).
