Application of biochar in modification of fillers in bioretention cells: A review

Biochar has been widely used in soil improvement and bioretention cells because of its low carbon content, easy preparation, environmental protection, and excellent performance. This study reviews the element composition, morphological structure, adsorption, hydrophobicity, and water-retention capacity of biochar applications in bioretention. The review focused on biochar's water-retention capacity, its influence on the water permeability of fillers, and its capacity to remove contaminants such as nitrogen, phosphorus, organic compounds, pathogenic microorganisms, and heavy metals in bioretention cells. This review summarizes the potential application of biochar-modified fillers, biochar-modified bioretention, and related problems, to guide the modification and application of biochar as a bioretention filler.