Wastewater Treatment Operator Certification Practice Test

Which of the following is true about the extended aeration process?

1. Wasting is not necessary to maintain proper control of the process

2. It produces more waste than conventional activated sludge process

3. It has low F/M ratio

4. It has low MLSS concentration

The correct answer is: It has low F/M ratio

The extended aeration process is designed to optimize the treatment of wastewater by providing a prolonged aeration period. This results in a low Food to Microorganism (F/M) ratio, which signifies that there is less organic material (food) available for the microorganisms (activated sludge) to feed on. A low F/M ratio is beneficial in this context because it promotes the growth of a more stable and diverse microbial population, which can effectively degrade organic pollutants over an extended period. In extended aeration systems, the microorganisms have adequate time to consume the available food, leading to better treatment efficiency and lower levels of residual pollutants in the effluent. This contrasts with conventional systems, which typically operate at higher F/M ratios, allowing for quicker treatment but potentially leading to less stable microbial populations and more frequent solids disposal needs. Additionally, this aspect of the extended aeration process plays a crucial role in reducing the need for frequent wasting of sludge, as it facilitates more complete treatment of the waste given the extended time for biodegradation. Therefore, the assertion that the extended aeration process has a low F/M ratio is accurate, illustrating an essential aspect of its operational characteristics and efficiency in treatment processes.