From carbon sequestration perspective: Adsorption of minerals enhances the stabilization of organic fractions in composting
Ziwei Jiao, Ruoqi Li, Kui Zhang, Yuhan Zhang, Yanbing Guo, Chang Su, Yuan Chang, Yuquan Wei, Zitong Kang, Yuhui Qiao, Jihong Li
Abstract
The crucial role of minerals in enhancing organic matter (OM) stabilization and humification during composting is increasingly recognized for carbon sequestration. This study aimed to investigate the effects of kaolinite and hematite on dissolved organic matter (DOM) characteristics, and humus fractions conversion in food waste composting, especially the heating (HP) and thermophilic phases (TP), and adsorption experiments. The results showed that after 40 days of composting, the 3D fluorimetric parallel factor analysis showed that mineral addition could promote the complexity of DOM structure, and the content of HA in each treatment increased to 60.6, 68.1, 69.4, 70.8, 66.1 mg/g, respectively, especially hematite in TP and kaolinite in HP. It can significantly increase the humus degree of compost by about 16%.The adsorption experiments show that minerals have selective adsorption of different DOM components, kaolinite has a strong adsorption capacity for humic acid in TP (70.75 mg/g), hematite has a strong adsorption capacity for fulvic acid in HP (83.3 mg/g). Structural equation modeling also indicated that mineral addition phase significantly influenced adsorption efficiency and humus formation. In this study, the relationship between the rapid maturation of aerobic compost and the transformation of organic matter components by mineral addition from the perspective of organic and inorganic complex was compared, and the differences between different minerals and different compost periods were compared, providing insights for the use of minerals to enhance the stability and humification of organic matter in compost, which helps to improve the carbon sequestration potential. • Hematite and kaolinite were compared in compost and batch adsorption experiment. • Hematite added in thermophilic and kaolinite in heating phase boost humification. • Hematite has higher maximum equilibrium adsorption capacity of DOM than kaolinite. • Hematite mainly selectively adsorbs FA, and kaolinite prefers HA.