Separation and degradation techniques for microplastics in soil environments

The soil environment plays a crucial role in maintaining ecological balance, and supporting agricultural production. However, excessive generation and improper management of plastic products have exacerbated the pollution level of microplastics (MPs) throughout the biosphere. MPs are generated when plastic waste products undergo degradation processes, including photodegradation, and oxidation. Thus, various physical, chemical, and biological techniques have been developed for the separation and degradation of soil MPs. However, most of the techniques are still in the laboratory stage due to the heterogeneity and complexity of the soil environment. As a result, the existing techniques for the separation and degradation of MPs are summarized to provide new insights and ideas into plastic waste management. This review introduces the sources, formation processes, and potential hazards of MPs to soil ecosystems and human health. In addition, it comprehensively discusses the existing feasible techniques for the separation and degradation of MPs, including density separation, advanced oxidation, bacterial degradation, and composite methods. In addition, it thoroughly analyzes and compares the principles, advantages, and disadvantages of each treatment technology. Finally, certain outlooks on the future development trends and challenges of MPs treatment technologies are presented, and directions and solutions for further research are pointed out.