What type of filtration is responsible for the nitrification process in aquatic systems?

The nitrification process in aquatic systems is primarily a biological filtration mechanism. This process is carried out by specialized bacteria that convert ammonia, which is toxic to aquatic life, into less harmful substances through two main steps: first, ammonia is oxidized to nitrite by ammonia-oxidizing bacteria, and then nitrite is further oxidized to nitrate by nitrite-oxidizing bacteria.

Biological filtration is essential in maintaining a healthy environment in aquaculture and aquarium systems, as it helps to regulate nitrogen levels and reduces the risk of toxic build-up from fish waste and uneaten food. The presence of a biological filter encourages the growth of these beneficial bacteria, leading to efficient nitrification.

In contrast, mechanical filtration involves the physical removal of particles from the water, such as uneaten food and debris, while chemical filtration uses media that can absorb or chemically alter substances in the water, such as activated carbon. Thermal filtration, although important for temperature regulation, does not contribute to the biochemical transformations required for nitrification. Thus, biological filtration is the only type among the options that specifically facilitates the nitrification process.