Wastewater Treatment Operator Certification Practice Test

What is accomplished by the activated sludge process?

1. Anaerobic bacteria use SO4 to eat incoming volatile solids

2. Remove soluble or finely divided suspended materials

3. Anoxic microorganisms destroy incoming BOD

4. Zoogleal breaks down influent organics

The correct answer is: Remove soluble or finely divided suspended materials

The activated sludge process is primarily designed to remove soluble and finely divided suspended materials from wastewater. This biological treatment method employs microorganisms, particularly bacteria, that thrive in an aerated environment. As the wastewater flows through the aeration tank, these microorganisms consume organic pollutants, effectively breaking down biochemical oxygen demand (BOD) and suspended solids. By promoting the growth of a diverse microbial population in the mixed liquor, the process enhances the degradation of conventionally dissolved organic matter, which is an essential step in reducing the overall contaminant load in the effluent. Moreover, the settling phase allows the activated sludge, which contains the microorganisms, to be separated from the treated water, further refining the quality of the effluent. The remaining sludge can then be returned to the aeration tank to maintain the microbial population, thereby sustaining the process and its effectiveness. Other options do not accurately reflect the primary function of the activated sludge process. For instance, while anaerobic processes do utilize sulfate as an electron acceptor, the activated sludge process primarily operates under aerobic conditions. The option about anoxic microorganisms pertains to a different type of treatment, while the mention of Zoogleal implies a more specific microbial function that does not encompass the broader microbial activity during the activated sludge process.