Effect of microscale ZVI/magnetite on methane production and bioavailability of heavy metals during anaerobic digestion of diluted pig manure

• Published in: Environmental science and pollution research international 2017-05, Vol.24 (13), p.12328-12337
• Main Authors: Liang, Yue-gan, Li, Xiu-juan, Zhang, Jin, Zhang, Li-gan, Cheng, Beijiu
• Format: Article
• Language: English
• Subjects: Alternative energy sources; Anaerobic digestion; Anaerobiosis; Animal wastes; Animals; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioavailability; Biodegradation; Biogas; Biological Availability; Chemical oxygen demand; Corrosion; Earth and Environmental Science; Ecotoxicology; Electron transfer; Environment; Environmental Chemistry; Environmental Health; Feasibility studies; Ferrosoferric Oxide; Heavy metals; Iron; Laboratories; Magnetite; Manure; Manures; Metals; Metals, Heavy; Methane; Microorganisms; Pig manure; Refuse as fuel; Research Article; Slurries; Swine; Toxicity; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-8832-9

Low methane production and high levels of heavy metal in pig slurries limit the feasibility of anaerobic digestion of pig manure. In this study, changes in the methane production and bioavailability of heavy metals in the anaerobic digestion of diluted pig manure were evaluated using single and combined action of microscale zero-valence iron (ZVI) and magnetite. After 30 days of anaerobic digestion, the methane yield ranged from 246.9 to 334.5 mL/g VS added, which increased by 20–26% in the group added with microscale ZVI and/or magnetite relative to that in the control group. Results of the first-order kinetic model revealed that addition of microscale ZVI and/or magnetite increased the biogas production potential, rather than the biogas production rate constant. These treatments also changed the distribution of chemical fractions for heavy metal. The addition of ZVI decreased the bioavailability of Cu and Zn in the solid digested residues. Moreover, a better performance was observed in the combined action of microscale ZVI and magnetite, and the ZVI anaerobic corrosion end-product, magnetite, might help enhance methane production through direct interspecies electron transfer in ZVI-anaerobic digestion process.