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

Qianyu Hang, Haiyan Wang, Zan He, Weiyang Dong, Zhaosheng Chu, Yu Ling, Guokai Yan, Yang Chang and Congyu Li
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Qianyu Hang: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Haiyan Wang: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Zan He: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Weiyang Dong: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Zhaosheng Chu: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Yu Ling: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Guokai Yan: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Yang Chang: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China
Congyu Li: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, No. 8 Da Yang Fang, Anwai, Chaoyang District, Beijing 100012, China

IJERPH, 2020, vol. 17, issue 5, 1-18

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 NO 3 − -N removal efficiency and denitrification rate of HSHAD were 94.4% and 1.3 g NO 3 − -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 NO 3 − -N removal efficiency and denitrification rate (79.1% and 1.1 g NO 3 − -N m −3 ·d −1 ) than HHD mesocosms (65.3% and 1.0 g NO 3 − -N m −3 ·d −1 ). As a whole, HSHAD mesocosms removed 58.8 mg NO 3 − -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 NO 3 − -N removal from agricultural runoff during long-term operation. The denitrificans containing narG (1.67 × 10 8 ± 1.28 × 10 7 copies g −1 mixture-soil −1 ), nirS (8.25 × 10 7 ± 8.95 × 10 6 copies g −1 mixture-soil −1 ), and nosZ (1.56 × 10 6 ± 1.60 × 10 5 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; carbon source; heterotrophic denitrification; sulfur autotrophic denitrification; agricultural runoff; constructed wetland mesocosms (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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