Sulphate radical-based advanced oxidation technologies for removal of COD and ammonia from hazardous landfill leachate: A review

Solid waste landfill (SWL) is known as a major pollution source contaminating air, water sources, and soil environment. The main hazard of SWL is leachate including high organic matter and nutrients. Recently, sulphate radical-based advanced oxidation processes (SR-AOPs) based on persulphate (PS) have been applied as a useful method for removal of chemical oxygen demand (COD) and ammonia from landfill leachate (LL). The removal efficiency of the SR-AOPs depends on effective parameters such as pH, oxidant dosage, catalyst dosage, temperature, reaction time, and so forth. Among SR-AOPs, thermal persulphate oxidation (TPO) seems to be promising for removal of both COD and ammonia; however, the high amount of energy cost is regarded as a major drawback. The drawbacks and future challenges for the use of SR-AOPs for LL have been discussed, and some strategies such as using coupled mechanisms of SR-AOPs have been proposed to tackle the common difficulties. Finally, the performance of SR-AOPs for treatment of LL has been compared with hydroxyl radical processes.

Automated summary

Solid waste landfill is a major pollution source that harms the environment. Sulphate radical-based advanced oxidation processes have been proven effective in treating landfill leachate, but energy consumption remains a challenge.