What type of microorganisms are most prevalent in a young (Low MCRT, High F:M) mixed liquor?

In a young mixed liquor characterized by low Mean Cell Residence Time (MCRT) and high Food to Microorganism (F:M) ratio, the microbial community typically consists of protists such as amoebas and flagellates. This is because, in an environment with plenty of available organic material, such as during the initial stages of treatment, flagellates thrive due to their ability to rapidly consume the high food supply. Amoebas also flourish under these conditions since they feed on bacterial populations and organic particles, which are abundant in a young mixed liquor.

The presence of these microorganisms indicates a rapidly changing environment that prioritizes the breakdown of organic matter, suggesting that conditions are optimal for growth. Their prevalence is crucial in enabling the efficient breakdown of organic contaminants found in the wastewater during this stage of treatment.