Influence of zero-valent iron nanoparticles on nitrate removal by Paracoccus sp

• Published in: Chemosphere (Oxford) Vol. 108; pp. 426 - 432
• Main Authors: Liu, Yan, Li, Shibin, Chen, Zuliang, Megharaj, Mallavarapu, Naidu, Ravi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-08-2014; Elsevier
• Subjects: Applied sciences; Biological and medical sciences; Biological denitrification; Biological treatment of waters; Biotechnology; Denitrification - drug effects; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Iron - chemistry; Iron - metabolism; Nanoparticles - chemistry; Nanoparticles - metabolism; Nanoparticles - ultrastructure; Nanotoxicology; Nitrates - isolation & purification; Nitrates - metabolism; nZVI; Paracoccus - drug effects; Paracoccus - growth & development; Paracoccus - metabolism; Paracoccus sp; Pollution; Temperature; Wastewaters; Water Pollutants, Chemical - isolation & purification; Water Pollutants, Chemical - metabolism; Water Purification - methods; Water treatment and pollution; X-Ray Diffraction; Biological denitrification; nZVI; Nanotoxicology; Paracoccus sp; Removal; Water treatment; Nanoparticle; Nitrogen compounds; Temperature effect; Iron III Ions; Zerovalent metal; Iron; Nitrates; Biological purification; Surface structure; Characterization; Iron II Ions; pH; Bacteria; Scanning electron microscopy; Iron II Iron III Oxides; Transition metal; Aerobe; X ray diffraction; Heavy metal; Operating conditions; Trace element; Energy-dispersive X-ray spectrometry; Inorganic anion; Paracoccus; Morphology; Denitrification; Nanostructured materials
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2014.02.045

•nZVI impacting on biodenitrification by Paracoccus sp.•Effect of nZVI on the growth of Paracoccus sp.•nZVI had little inhibitory of denitrification and cell growth.•SEM, XRD and EDS for the characterization of nZVI.
Nitrate contamination in drinking water is a major threat to public health. This study investigated the efficiency of denitrification of aqueous solutions in the co-presence of synthesized nanoscale zero-valent iron (nZVI; diameter: 20–80nm) and a previously isolated Paracoccus sp. strain YF1. Various influencing factors were studied, such as oxygen, pH, temperature, and anaerobic corrosion products (Fe2+, Fe3+ and Fe3O4). With slight toxicity to the strain, nZVI promoted denitrification efficiency by providing additional electron sources under aerobic conditions. For example, 50mgL−1 nZVI increased the nitrate removal efficiency from 66.9% to 85.2%. However, a high concentration of nZVI could lead to increased production of Fe2+, a toxic ion which could compromise the removal efficiency. Kinetic studies suggest that denitrification by both free cells, and nZVI-amended cells fitted well to the zero-order model. Temperature and pH are the major factors affecting nitrate removal and cell growth, with or without the presence of nZVI. In this study, nitrate removal and cell growth increased in the pH range of 6.5–8.0, and temperature range of 25–35°C. These conditions favor the growth of the strain, which dominated denitrification in all scenarios involved. As for anaerobic corrosion products, compared with Fe2+ and Fe3+, Fe3O4 promoted denitrification by serving as an electron donor. Finally, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirmed attachments of nZVI on the surface of the cell, and the formation of iron oxides. This study indicated that, as an electron donor source with minimal cellular toxicity, nZVI could be used to promote denitrification efficiency under biotic conditions.