The roles of phosphorus species formed in activated biochar from rice husk in the treatment of landfill leachate

Untreated landfill leachate is a threat to the environment. Here, the phosphoric acid activated biochars prepared from rice husk were successfully used for leachate treatment to achieve a high removal of color (100%), pollutants ( > 90%), chemical oxygen demand (similar to 80%) and NH4+-N (100%). The leachate treatment process on phosphoric acid activated biochar could be well described by the pseudo-second order and Langmuir isotherm model, and it was controlled by external mass transfer followed by intra-particle diffusion. The phosphorus species formed in activated biochar could adjust and control the textural properties and structures of biochar, while the phosphorus species of activated biochar could attract humic acid-like organics in the leachate via hydrogen bond and pi-pi interactions, which were found to significantly enhance the treatment of leachate. The findings provided important insights for efficient treatment of wastewater using agricultural waste residues on an industrial scale.