What is the primary method employed in biological filtration?

The primary method employed in biological filtration is indeed microbial activity breaking down pollutants. This process utilizes a diverse community of microorganisms, including bacteria, fungi, and protozoa, that thrive in a biofilm on the surface of filter media. These microorganisms play a critical role in degrading organic matter and other pollutants present in the water, leading to effective purification.

Through metabolic processes, these microbes convert harmful substances into less harmful forms or even completely mineralize them into harmless byproducts such as carbon dioxide and water. This degradation process is essential, especially in applications like wastewater treatment, where the reduction of organic loading and nutrient removal are key objectives. Additionally, the efficiency of biological filtration can be enhanced by creating optimal environmental conditions for microbial growth, such as maintaining appropriate temperature, pH, and nutrient levels.

Each of the other options represents different methods of treating water but does not encompass the fundamental process of biological filtration. For example, chemical reactions may involve adding chemicals to treat water but do not rely on microbial activity. Physical filtration through membranes involves sieving particles from water but does not utilize biological processes. Ultraviolet radiation is effective for disinfection but also does not engage microbial breakdown mechanisms in the filtration process. Thus, the role of microbial activity in biological filtration stands