Municipal solid waste landfill leachate is a type of polluted water that needs to be treated before being released into the environment. Different methods like physical, chemical, and biological treatments are used for this purpose. Currently, aerobic treatment combined with chemical and physical methods is commonly used, but it has some limitations. Researchers have found that anaerobic treatment of landfill leachate using bioreactors is a more cost-effective and efficient method. This method helps in removing organic matter and toxic pollutants from the leachate, making it safer for the environment.