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Nitrate removal from ground water the focus of 3 studies

Xi’an, China – Three recently published research papers focus by on nitrate removal from ground water.

The research papers, titled, “Efficient autotrophic denitrification performance through integrating the bio-oxidation of Fe(II) and Mn(II),” “Comparison of denitrification performance by bacterium Achromobacter sp. A 14 under different electron donor conditions” and “Effect of mixed electron donors on autotrophic denitrification by Pseudomonas sp. SZF15” were written by Junfeng Su.

The three papers deal with nitrate removal from ground water. In most cases, ground water from anoxic acquifiers contain excessive levels of iron, manganese and/or nitrogen, according to a news release.

According to Junfeng and his team, high concentrations of Fe(II) and Mn(II), which co-existed in the natural ground water body, could be easily oxidized as the electron donor. On the other hand, the team observed that transformation from nitrate/nitrite to N2 (i.e., denitrification process) usually consumed the electrons and this according to them could be regarded as an electron acceptor. Therefore, Junfeng and others concluded that coupling denitrification process with oxidation of Fe(II) and Mn(II) might develop a new type of autotrophic denitrification which could aid in simultaneous removal of nitrate, nitrite, ferrous and manganese.

In the paper titled, “Efficient autotrophic denitrification performance through Integrating the bio-oxidation of Fe(II) and Mn(II),” according to Junfeng and the team, high concentrations of Fe(II) and Mn(II), which co-existed in the natural ground water body, could be easily oxidized as the electron donor. Junfeng and the team proposed a novel and efficient strain Pseudomonas. sp. H117-based bioremediation process. Furthermore, the kinetics and parameters about substrate (nitrate) and substrate self-inhibition (nitrite) were obtained. The results showed that the Edwards model used by the team suited their experimental data. It was also assessed that Fe(II) and Mn(II) could be formed to biogenic Fe-Mn oxides (FeOOH and MnO2) via microbial oxidation. The research is published in Chemical Engineering Journal.

In the paper titled, “Comparison of denitrification performance by bacterium Achromobacter sp. A 14 under different electron donor conditions,” Junfeng Su mentions the use of heterotrophic, mixotrophic and autotrophic denitrification in the treatment of nitrate-contaminated water. While conducting the study a newly anaerobic denitrifying bacterium, A14, with high denitrification and Mn(II) oxidation ability was isolated from sediments. This process made his study easier. It exhibited efficient denitrification ability in all the three mediums: autotrophic, mixotrophic and heterotrophic. Furthermore, the meteorological chromatography findings suggested that N2 and N2O were detected in the gas produced by strain A14. It was also concluded that the characteristic of gas composition varied in different mediums. The research is published in Chemical Engineering Journal.

In the paper titled, “Effect of mixed electron donors on autotrophic denitrification by Pseudomonas sp. SZF15,” a mixed electron donors of Mn(II) and Fe(II) were tested for their effects on autotrophic denitrification. Complete nitrate removal was found at high Mn(II)/Fe(II) molar ratios, 30 °C, pH 7.0, and an electron donor/electron acceptor molar ratio of 3.00.Furthermore, In addition to the above, the findings showed that nitrate could be converted to nitrite and further be degraded to N2 by nitrite reductase (nirS). This research is published in Industrial and Engineering Chemistry Research.

Junfeng Su is a doctoral tutor and fellow of the International Water Association (IWA). He is a professor at the School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology of China. He is a member of the innovation team, “Northwestern Town Water Resources Recycling and Water Quality Safety Guarantee” of the Ministry of Education. Su is the principal investigator of eight national or provincial programs including National Natural Science Foundation of China, Excellent Youth Foundation of Shaanxi Province, EY Research and Development Project of Shaanxi Province of China, and Doctoral Fund of Ministry of Education of China.