Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Feb 29;17(5):1574.
doi: 10.3390/ijerph17051574.

Hydrilla verticillata-Sulfur-Based Heterotrophic and Autotrophic Denitrification Process for Nitrate-Rich Agricultural Runoff Treatment

Qianyu Hang  1   2 , Haiyan Wang  1   2 , Zan He  1   3 , Weiyang Dong  1   2 , Zhaosheng Chu  1   4 , Yu Ling  1   2 , Guokai Yan  1   2 , Yang Chang  1   2 , Congyu Li  1   2
Affiliations

Hydrilla verticillata-Sulfur-Based Heterotrophic and Autotrophic Denitrification Process for Nitrate-Rich Agricultural Runoff Treatment

Qianyu Hang et al. Int J Environ Res Public Health. .

Abstract

Hydrilla verticillata-sulfur-based heterotrophic and autotrophic denitrification (HSHAD) process was developed in free water surface constructed wetland mesocosms for the treatment of nitrate-rich agricultural runoff with low chemical oxygen demand/total nitrogen (C/N) ratio, whose feasibility and mechanism were extensively studied and compared with those of H. verticillata heterotrophic denitrification (HHD) mesocosms through a 273-day operation. The results showed that the heterotrophic and autotrophic denitrification can be combined successfully in HSHAD mesocosms, and achieve satisfactory nitrate removal performance. The average NO3--N removal efficiency and denitrification rate of HSHAD were 94.4% and 1.3 g NO3--N m-3·d-1 in steady phase II (7-118 d). Most nitrate was reduced by heterotrophic denitrification with sufficient organic carbon in phase I (0-6 d) and II, i.e., the C/N ratio exceeded 4.0, and no significant difference of nitrate removal capacity was observed between HSHAD and HHD mesocosms. During phase III (119-273 d), sulfur autotrophic denitrification gradually dominated the HSHAD process with the C/N ratio less than 4.0, and HSHAD mesocosms obtained higher NO3--N removal efficiency and denitrification rate (79.1% and 1.1 g NO3--N m-3·d-1) than HHD mesocosms (65.3% and 1.0 g NO3--N m-3·d-1). As a whole, HSHAD mesocosms removed 58.8 mg NO3--N more than HHD mesocosms. pH fluctuated between 6.9-9.0 without any pH buffer. In general, HSHAD mesocosms were more stable and efficient than HHD mesocosms for NO3--N removal from agricultural runoff during long-term operation. The denitrificans containing narG (1.67 × 108 ± 1.28 × 107 copies g-1 mixture-soil-1), nirS (8.25 × 107 ± 8.95 × 106 copies g-1 mixture-soil-1), and nosZ (1.56 × 106 ± 1.60 × 105 copies g-1 mixture-soil-1) of litter bags and bottoms in HSHAD were higher than those in HHD, which indicated that the combined heterotrophic and autotrophic denitrification can increase the abundance of denitrificans containing narG, nirS, and nosZ, thus leading to better denitrification performance.

Keywords: Hydrilla verticillata; agricultural runoff; carbon source; constructed wetland mesocosms; heterotrophic denitrification; sulfur autotrophic denitrification.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Comparison of COD and C/N ratio profile within each mesocosm; (b) Comparison of pH and denitrification rate profile within each mesocosm, p > 0.05; (c) Comparison of NO3−-N concentrations and removal efficiency profile within each mesocosm.
Figure 2
Figure 2
Compositional proportions of different peak intensities for HSHAD and HHD mesocosms during the operation.
Figure 3
Figure 3
SO42− characteristics of each mesocosm during the experimental period.
Figure 4
Figure 4
The abundance of denitrifying narG (a), nirS (b), and nosZ (c) genes in mesocosms (error bars represent standard errors of the mean value).
See this image and copyright information in PMC

References

    1. Mirvish S.S. Proceedings of the Conference on Nitrogen as a Water Pollutant. Elsevier; Amsterdam, The Netherlands: 2013. N-nitroso compounds, nitrite, and nitrate: Possible implications for the causation of human cancer; pp. 195–207.
    1. Ballantine K.A., Groffman P.M., Lehmann J., Schneider R.L. Stimulating nitrate removal processes of restored wetlands. Environ. Sci. Technol. 2014;48:7365–7373. doi: 10.1021/es500799v. - DOI - PubMed
    1. Iamchaturapatr J., Yi S.W., Rhee J.S. Nutrient removals by 21 aquatic plants for vertical free surface-flow (VFS) constructed wetland. Ecol. Eng. 2007;29:287–293. doi: 10.1016/j.ecoleng.2006.09.010. - DOI
    1. Bachand P.A., Horne A.J. Denitrification in constructed free-water surface wetlands: II. Effects of vegetation and temperature. Ecol. Eng. 1999;14:17–32. doi: 10.1016/S0925-8574(99)00017-8. - DOI
    1. Mander Ü., Tournebize J., Kasak K., Mitsch W.J. Climate regulation by free water surface constructed wetlands for wastewater treatment and created riverine wetlands. Ecol. Eng. 2014;72:103–115. doi: 10.1016/j.ecoleng.2013.05.004. - DOI

Publication types

LinkOut - more resources