Which condition is most beneficial for microbial activity during sewage treatment?

Stable and optimal temperature is crucial for microbial activity during sewage treatment because microorganisms, such as bacteria and protozoa, thrive within specific temperature ranges. At these optimal temperatures, metabolic processes are maximized, allowing for efficient breakdown of organic matter in sewage. When temperatures are stable, microorganisms can maintain their reproductive rates and overall activity without the stress that often accompanies fluctuations.

In contrast, high salt concentration can inhibit microbial growth by creating an environment that is osmotically unfavorable for many freshwater organisms. Low pH levels can also harm microbial populations, as extreme acidity can kill or hinder the growth of various microbes essential for effective sewage treatment. Rapid fluctuations in conditions, including temperature, pH, or other environmental factors, can lead to stress for microorganisms, reducing their efficiency and potentially resulting in system failures. Thus, maintaining a stable and optimal temperature is the most beneficial condition for promoting microbial activity in sewage treatment processes.