High suspended solids and BOD are most probably associated with which type of organisms?

High suspended solids and biochemical oxygen demand (BOD) are typically associated with flagellates. Flagellates are a type of protozoa that have one or more whip-like structures called flagella, which allow them to swim freely in aquatic environments. They are often found in environments with high nutrient loads, where organic matter is abundant.

When organic matter breaks down, it increases BOD, which can lead to a condition where the water becomes rich in suspended solids, as detritus and microbial populations grow. Flagellates thrive in these conditions because they feed on organic matter and bacteria. Their presence indicates a rich microbial community reacting to high nutrient levels.

Understanding the association between flagellates and high suspended solids and BOD is crucial because it helps wastewater operators identify the health of the biological treatment processes in wastewater treatment facilities. High levels of these organisms can indicate the system is processing organic material, which is essential for effective treatment.