Optimizing feedstock organic composition to regulate humification and heavy metal passivation during solid-state anaerobic digestion

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 499; p. 156071
• Main Authors: Guan, Weiting, Ansari, Ashley J., Yin, Rongrong, Qi, Chuanren, Song, Xiaoye
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2024
• Subjects: Heavy metal passivation; Humus formation; Organic component; Organic solid wastes; Solid-state anaerobic digestion; Organic component; Heavy metal passivation; Organic solid wastes; Solid-state anaerobic digestion; Humus formation
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.156071

[Display omitted] •Optimized organic composition boosts SSAD humification and HMs passivation.•Increasing proteins and lignocellulose enhanced HMs complexation in SSAD.•Environmental factors, especially pH, significantly influence HMs passivation. This study uncovered the impacts of feedstock organic composition, comprising proteins, lignocellulose, and lipids, on humification and passivation of heavy metals (HMs) in solid-state anaerobic digestion (SSAD). Mantel tests and partial least squares structural equation modeling (PLS-SEM) results revealed that copper (Cu) and zinc (Zn) passivation predominantly occurred through complexation with humic acid (HA). In contrast, lead (Pb) and chromium (Cr) passivation were pH-dependent as influenced by substrate conditions in SSAD. Increasing protein content in the feedstock facilitated lignocellulose biodegradation to enhance HA formation, and thus augmenting Cu and Zn passivation. Furthermore, the improved biodegradation of organic components elevated the substrate pH, further enhancing Pb and Cr passivation. Such improvement was notable when the protein: lignocellulose: lipid ratio of feedstock was regulated to 4.1:3.7:2.2, which increased HA contents to 35.25% and pH to 9 to enhance the passivation of Cu, Pb, and Cr by 0.48%, 52.0%, and 17.9%, respectively.