Chapter 15 - Activated Sludge Processes

Abstract

Chapter 15 introduces the activated sludge process principles and corresponding major treatment unit types. The activated sludge process is compared with percolating filtration, its greatest rival for domestic wastewater treatment in many countries. Different activated sludge process types are explained: the conventional complete mix activated sludge process, the series or plug flow system, tapered aeration, the step feed activated sludge process, the high-rate activated sludge process, extended aeration, contact stabilization, oxidation ditches, and the deep shaft process. Important activated sludge process designs and kinetics are outlined. These include diffused air aeration, mechanical aerators, and process design. Finally, the key design criteria loading rate, reactor type, oxygen demand, and nutrient requirements are summarized. At the end of this chapter, the audience should appreciate key activated sludge process design and operation principles. Moreover, readers should be able to decide which is the best activated sludge process type for a specific case study.