What kind of organisms primarily contribute to the treatment process in a trickling filter?

In a trickling filter, the primary organisms involved in the treatment process are bacteria and protozoa. This type of wastewater treatment relies on biofilms that develop on the surface of media, such as rocks or plastic that are designed to maximize surface area. Bacteria are the primary agents of decomposition in this environment; they break down organic matter in the wastewater as it trickles over the surface. These microorganisms thrive in the moist conditions provided by the wastewater and efficiently metabolize nutrients, leading to a reduction in pollutants.

Protozoa also play a critical role in the trickling filter system. They consume bacteria, thereby helping to control bacterial population levels and contributing to the overall stability of the biological treatment process. By consuming excess bacteria and organic matter, protozoa help maintain a balanced ecosystem within the filter.

The other options involve organisms that are not primarily engaged in the treatment process within a trickling filter. Invertebrates, crustaceans, fish, amphibians, and aquatic plants may exist in or around aquatic environments but do not contribute to the biofilm that is essential for the bacterial and protozoan treatment mechanisms in these systems. Understanding the dominant role of bacteria and protozoa in trickling filters is essential for recognizing how biological wastewater treatment