Effect of Pyrolyzed Peach Pit Biomass on Dispersion and Sedimentation Characteristics of Saline Clay

Kaolin and Bentonite the have potential to be used in landfill liners. Leachate in the landfill changes the properties of dispersion and sedimentation of the liners. There is a little research being conducted to investigate on how to reduce the influence of the salt on properties of clay. Soil salinity causes salt accumulation, detrimentally impacting soil structure degradation, impaired water infiltration, and consequent soil degradation. Despite the recognized efficacy of biochar (i.e., a carbon negative material) as a soil amendment for improving soil structure, its application to ameliorate saline-alkali soils remains insufficiently understood. This study attempted to improve the understanding of dispersion and sedimentation characteristics of saline clay soil under different porewater salinities (0%, 1%, 5%, 10%) and varying contents of biochar (0%, 5%, 10%). The results revealed that biochar-amended saline soil enhanced aggregation of dispersed soil particles, forming larger aggregates and promoting flocculation, effectively improving the dispersibility of clay and saline soil. The cation exchange capacity (CEC) of biochar is crucial for enhancing the soil aggregation in saline environments, countering the negative effects of high salt on soil structure. Biochar promotes soil particle aggregation by increasing CEC. At higher porewater salinities (i.e., 5%, 10%), the sedimentation property of soil particles in biochar was relatively inconsistent with expectations, exhibiting a slowed sediment rate and reduced soil sedimentation height. This difference was attributed to the adsorption of sodium ions by the functional groups and porous structure of biochar, decreasing the influence of salt addition dispersion and sedimentation characteristics. Based on these findings, it can be concluded that the application of biochar effectively enhanced soil physicochemical properties and improved soil structure.