An overview of comparing chemical oxygen demand removal methods from landfill leachate

Aims: Landfill leachate contains many pollutants including chemical oxygen demand (COD), biological oxygen demand, ammonia nitrogen, organic matter, minerals, and toxins. Given the importance of COD removal from landfill leachate, this study was conducted to evaluate and compare different methods used for the removal of COD from leachate. Materials and Methods: This study was conducted as a narrative review using keywords of leachate, COD, landfill in related journals issued in scientific databases such as Web of Science, PubMed, SID, and Google Scholar. We reviewed different aspects of COD removal from leachate to find better options in this respect. Results: The highest rate of COD removal was observed for batch reactor methods of anaerobic and aerobic granular activated carbon and electro Fenton by 98.4% COD removal, and the lowest one was 22.7% for the electro-Fenton method. The most commonly used methods for removing COD from solidwaste leachate have been physical and chemical methods. Conclusion: This study showed that a wide range method has been used to remove COD from leachate. It seems that combined methods are more effective to reduce the content of leachate COD. Besides, methods such as Fenton and absorption are more preferable because of simple application and low energy consumption.