The study looked at improving water quality in landfills by using a method called leachate circulation. By circulating the leachate, the water content in the waste was controlled, leading to better degradation of organic matter by microorganisms. The concentration of pollutants in the leachate was significantly reduced in the system using leachate circulation compared to traditional methods. However, issues like acid accumulation and high levels of certain pollutants still need to be addressed in future research.