Which type of filtration relies on bacterial populations for the nitrification process?

Biological filtration is essential in aquatic systems as it harnesses the activity of specific bacterial populations to convert toxic ammonia, which is produced from fish waste and decomposing organic matter, into less harmful substances. This process, known as nitrification, involves two main groups of bacteria: ammonia-oxidizing bacteria (AOB) that convert ammonia into nitrite, and nitrite-oxidizing bacteria (NOB) that further convert nitrite into nitrate. The establishment and maintenance of a healthy bacterial colony in a biological filter are vital for the effective functioning of an aquatic ecosystem, helping to maintain water quality and protect aquatic organisms from toxic buildup.

In contrast, mechanical filtration physically removes particulates from the water without affecting chemical composition or contributing to biological processes. Chemical filtration involves the use of substances such as activated carbon to remove specific pollutants or unwanted chemicals from the water, again without the involvement of bacterial populations. UV filtration uses ultraviolet light to sterilize the water by inactivating microorganisms, but does not utilize bacterial processes for purifying the water. Therefore, the reliance on bacterial populations for the nitrification process distinctly identifies biological filtration as the correct choice in this context.