Mechanism of aerobic denitrifiers and calcium nitrate on urban river sediment remediation

• Published in: International biodeterioration & biodegradation 2018-01, Vol.126, p.119-130
• Main Authors: Tang, Yinqi, Li, Meng, Zou, Yanan, Lv, Mengyi, Sun, Jingmei
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Bacteria; Biodegradation; Bioremediation; Calcium; Calcium nitrate; Carbon; Chemical compounds; Enzymatic activity; Fluvial sediments; Low concentrations; Low molecular weights; Microorganisms; Miseq high-throughput sequencing technique; Molecular weight; Next-generation sequencing; Nitrates; Nitrogen; Nitrogen removal; Nitrogen transformation; Organic carbon; Organic compounds; Organic matter; Organic structure; Phenoloxidase; Phenols; Pollutant removal; Pollutants; Pollution control; Remediation; Rivers; Sediment pollution; Sediment remediation; Sediments; Total organic carbon; Urease; Water pollution
• ISSN: 0964-8305; 1879-0208
• DOI: 10.1016/j.ibiod.2017.10.002

Calcium nitrate, coupled with aerobic denitrifiers, were applied to reduce nitrogen and organic pollutants of urban river sediment. 115-day remediation tests showed that total nitrogen in the sediment decreased by 16.5%, while total transferable nitrogen increased from 0.097 to 0.109 mg/g. Increased urease activity and decreased protease showed a potential for further nitrogen degradation. Although the total organic carbon (TOC) content decreased slightly, the predominant organic pollutants were removed or converted to low molecular weight compounds through microbial biodegradation. Decreased phenol oxidase activity exhibited that low concentrations of recalcitrant aromatic compounds remained in the sediment. The high-throughput sequencing results reveals that the community diversity of bacteria markedly increased. Compared with the addition of calcium nitrate or aerobic denitrifiers alone, genera mainly removed nitrogen and organic compounds, especially recalcitrant compounds, following the treatment with the combination technology. Moreover, the concentrations of nitrogen and organic matter did not increase significantly in the overlying water, which was free of undesirable secondary pollution. During the process of remediation, dosing with nitrate may provide a more favorable environment for aerobic denitrifiers and indigenous microbes in the sediment. Furthermore, the introduced aerobic denitrifiers may improve nitrogen removal and have a collaborative effect with indigenous microbes. •The combination technology had significant removal efficiencies of nitrogen and organic matter in urban river sediment.•The predominant organic pollutants were converted to low molecular weight compounds through microbial biodegradation.•Enzymatic activities indicated the potential of nitrogen degradation and low concentrations of recalcitrant compounds.•The community diversity of bacteria markedly increased after 115 days of treatment.