California Wastewater Treatment Operator Practice Exam

Extended aeration is a process used in wastewater treatment that involves longer retention times in the treatment tank, typically between 24-36 hours. This allows for more complete biological treatment of the wastewater. Option B is incorrect because extended aeration is an aerobic process, meaning it occurs in the presence of oxygen, not in the absence of oxygen as in anaerobic processes. Option C is also incorrect because extended aeration does require some operator attention to monitor and control the process. Option D is incorrect because extended aeration typically produces less excess sludge compared to other treatment methods, making it a more efficient process. Therefore, option A is the most accurate statement since oxidation ditches, which are commonly used in extended aeration, are designed for smaller flows and are operated in extended aeration mode.