Binding characteristics of heavy metal contaminations and sewage sludge DOM products: Determination based on complexing-variance partitioning analysis

Dissolved organic matter (DOM), known for its ability to influence the environmental geochemical behavior of heavy metals, is widely regarded as an eco-friendly substance for mitigating heavy metal pollution in the environment. Understanding the unique properties of DOM as a ligand is essential for comprehending its impact on the migration and toxicity of metal pollutants. In this study, sewage sludge composting DOM components were used as ligands for the biding of heavy metal contaminants. Parallel factor analysis (PARAFAC) and variance partitioning analysis (VPA) was employed to analyze the complexing properties. Four DOM components were found in sewage sludge composting products. The identified DOM components in sewage sludge showed significant complexing ability with Zn, Cu and Cr, rather than Pb. Furthermore, based on VPA analysis, the heavy metal contaminants-binding contribution scores of each DOM components showed that simple structure DOM component C1 showed high Zn, Cu and Cr-binding ability. However, high humification degree DOM components presented high stability which could be employed for long-term heavy metals contaminants control. These promising findings provide valuable insights into the distinct binding properties of various DOM components with contaminants. This characterization serves as a theoretical foundation to support efforts in heavy metals control.