What measurement reflects the health of an activated sludge system?

The measurement that reflects the health of an activated sludge system is gas production. In activated sludge systems, the presence of microorganisms plays a crucial role in the biological treatment of wastewater. These microorganisms metabolize organic matter and produce gases, primarily carbon dioxide, as they break down waste.

The volume and composition of gas produced can provide insight into the microbial activity within the system. A healthy and active microbial population is indicative of effective treatment processes. If gas production is occurring at desirable levels, it signifies that the microorganisms are functioning properly, thus supporting efficient degradation of organic matter in the wastewater. Monitoring gas production helps operators assess the health and efficiency of the activated sludge system, ensuring that it is operating optimally to treat wastewater effectively.

In contrast, while water temperature can influence microbial activity and overall system performance, it is not a direct measurement of the system's health. Retention time is important for ensuring that microorganisms have sufficient time to treat the wastewater but does not reflect microbial activity directly. Similarly, dissolved solids levels provide information about the concentration of solid materials in the effluent but do not specifically indicate the metabolic activity of the activated sludge.