Trickling filters are a type of wastewater treatment system that uses a bed of media, such as rocks or plastic, to support the growth of microorganisms. As wastewater flows over this media, the microorganisms break down organic matter, helping to purify the water. This process is often used in municipal and industrial settings to reduce pollution before the water is released into the environment. The design of trickling filters allows for efficient aeration, as air can circulate freely around the media. This promotes the growth of beneficial bacteria, which are essential for the treatment process. Trickling filters are a cost-effective solution for treating wastewater, making them popular in many regions.