Applications of plant and animal-based biochar: Insight into environmental remediation and biofuel production

Biochar is generated from plants (crop residues) and animal (bone waste) sources for environmental applications. However, the effects of plant-based biochar (PBC) and animal bone waste-derived biochar (ABWBC) in wastewater treatment (WWT), soil remediation, biofuel production, and polymer fillings have not been fully covered. Thus, this review comprehended the role of both PBC and ABWBC in WWT, soil remediation, biodiesel production, and anaerobic digestion (AD). The literature revealed that ABWBC has lesser carbon content and a higher surface area than PBC. PBC and ABWBC improved the pollutant's adsorption, nutrient availability, and microbial colonization in contaminated soil. Biochar supplementation enhanced the removal of emerging contaminants and antibiotics from wastewater, depending on the pyrolysis conditions. PBC and ABWBC catalysts enhanced esters' separation and efficient conversion to biodiesel (>90 %). The high calcium content in ABWBC supported microbial nexus and biogas production (>40 %) in AD. However, more concrete studies are still required to explore the effects of ABWBC on biodiesel production, polymer fillings, and microbial nexus in AD.