Biological treatment is a method of treating contaminants in water, soil, or air using biological organisms such as bacteria, algae, or fungi. These organisms break down or transform harmful substances into non-toxic or less harmful forms through natural processes like metabolism or fermentation. Biological treatment is often used in wastewater treatment plants, landfills, and other industrial facilities to remove pollutants and improve environmental quality. This method is considered to be environmentally-friendly and cost-effective compared to other conventional treatment methods.