Activated sludge processes and recent advances

The activated sludge is a traditional biological treatment, using microorganisms mixed with suspended solids in the mixture to treat domestic and industrial wastewater. It can achieve high treatment efficiencies with a wide variety of emerging organic pollutants present in the wastewater. This chapter aims to provide (1) the fundamentals of the activated sludge process, including microbial community characteristics, microbial growth kinetics, and environmental factors; (2) advanced technologies with activated sludge such as sequencing batch reactor, UNITANK system, and intermittent cycle extended aeration system; and (3) applications of activated sludge processes to remove emerging pollutants in wastewater. Also, the energy and cost required to treat wastewater by activated sludge were highlighted. Finally, this chapter provides a comprehensive review of the activated sludge process, leading to its application for wastewater treatment in further research.