Functionalized biochar for enhancing the removal of antibiotics and resistance genes in swine manure composting: A review

Since the antibiotics typically employed for growth promotion and disease treatment in animals, a considerable quantity of antibiotics is retained in swine manure (SM). The inappropriate handling of SM may lead to the release of antibiotics into the natural environment, resulting in the development of antibiotic resistance genes (ARGs), posing significant risks to both the ecological system and human health. Biochar (BC), a carbon-rich, porous material derived from biomass pyrolysis , has emerged as a promising solution for mitigating ARGs risks during SM composting. To enhance the adsorption performance of BC, functional BC (physical, chemical, biological or composite material modification) has attracted widespread attention. This work presented a review of the various modification methods and performance improvement mechanisms of BC, especially the environmentally friendly earthworm-modified BC. The differences in adsorption mechanisms of antibiotics and ARGs by modified BC were compared and analyzed, revealing that biodegradation played a crucial role in the removal of these substances during the SM composting. Finally, the review identified current challenges and outlines prospective avenues for further investigation to achieve a greater role for functionalized BC in the treatment of antibiotics in SM compost, thereby contributing to more sustainable and environmentally responsible waste management strategies. • Biochar is an effective method to reduce resistance risk of in swine manure compost. • Adsorption capacity of biochar for antibiotics and ARGs improved by functionalization. • Biochar could remove antibiotics and ARGs by regulating the microbial community. • Challenges on biochar should focus on the mechanism of removing antibiotics and ARGs.