Inhibition or promotion of biodegradation of nitrate by Paracoccus sp. in the presence of nanoscale zero-valent iron

• Published in: The Science of the total environment Vol. 530-531; pp. 241 - 246
• Main Authors: Jiang, Chenghong, Xu, Xuping, Megharaj, Mallavarapu, Naidu, Ravendra, Chen, Zuliang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.10.2015
• Subjects: Biodegradation, Environmental; Biodenitrification; Cell growth; Iron - chemistry; Metal Nanoparticles - chemistry; Nanotoxicity; Nitrates - chemistry; Nitrates - metabolism; nZVI; Paracoccus - physiology; Paracoccus sp; Soil Pollutants - chemistry; Soil Pollutants - metabolism; Nanotoxicity; Cell growth; nZVI; Biodenitrification; Paracoccus sp
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.05.044

To investigate the effect of nanoscale zero-valent iron (nZVI) on the growth of Paracoccus sp. strain and biodenitrification under aerobic conditions, specific factors were studied, pH, concentration of nitrate, Fe (II) and carbon dioxide. Low concentration of nZVI (50mg/L) promoted both cell growth and biodegradation of nitrate which rose from 69.91% to 76.16%, while nitrate removal fell to 67.10% in the presence of high nZVI concentration (1000mg/L). This may be attributed to the ions produced in nZVI corrosion being used as an electron source for the biodegradation of nitrate. However, the excess uptake of Fe (II) causes oxidative damage to the cells. To confirm this, nitrate was completely removed after 20h when 100mg/L Fe (II) was added to the solution, which is much faster than the control (86.05%, without adding Fe (II)). However, nitrate removal reached only 45.64% after 20h, with low cell density (OD600=0.62) in the presence of 300mg/L Fe (II). Characterization techniques indicated that nZVI adhered to microorganism cell membranes. These findings confirmed that nZVI could affect the activity of the strain and consequently change the biodenitrification. •Biodenitrification by Paracoccus sp. in the presence of nZVI was studied.•Biodegradation was promoted at a low nZVI concentration.•Biodegradation was inhibited at a high nZVI concentration.•nZVI that adhered to microorganism cell membranes was characterized.