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Zuo S, Wang Y, Wu J, Zhong F, Kong L, Chen Y, Cheng S. A partial siphon operational strategy strengthens nitrogen removal performance in partially saturated vertical flow constructed wetlands. CHEMOSPHERE 2024; 361:142475. [PMID: 38810809 DOI: 10.1016/j.chemosphere.2024.142475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 05/07/2024] [Accepted: 05/27/2024] [Indexed: 05/31/2024]
Abstract
The carbon‒oxygen balance has always been problematic in constructed wetlands (CWs), putting pressure on stable and efficient nitrogen removal. In this study, a novel partial siphon operational strategy was developed to further optimize the carbon and oxygen distributions of a partially saturated vertical flow CW (SVFCW) to enhance nitrogen removal. The removal performances of the partial siphon SVFCW (S-SVFCW) were monitored and compared with those of the SVFCWs at different partial siphon depths (15 cm, 25 cm and 35 cm) in both the warm and cold seasons. The results showed that the partial siphon operating strategy significantly facilitated the removal of ammonia and total nitrogen (TN) in both the warm and cold seasons. When the partial siphon depth was 25 cm, the S-SVFCWs had the highest TN removal efficiency in both the warm (71%) and cold (56%) seasons, with an average improvement of 46% and 52%, respectively, compared with those of the SVFCWs. The oxidation‒reduction potential (ORP) results indicated that richer OPR environments and longer hydraulic detention times were obtained in the S-SVFCWs, which enriched the denitrification bacteria. Microbial analysis revealed greater nitrification and denitrification potentials in the unsaturated zone with enriched functional genes (e.g., amo_AOA, amo_AOB, nxrA and nirK), which are related to nitrification and denitrification processes. Moreover, the strengthening mechanism was the intensified oxygen supply and carbon utilization efficiency based on the cyclic nitrogen profile analysis. This study provides a novel partial siphon operational strategy for enhancing the nitrogen removal capacity of SVFCWs without additional energy or land requirements.
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Affiliation(s)
- Shangwu Zuo
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Yueyuan Wang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Juan Wu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Fei Zhong
- School of Life Sciences, Nantong University, Nantong, 226019, China
| | - Lingwei Kong
- Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, 310024, China
| | - Yue Chen
- Hebei Construction Group Installation Engineering Co., Ltd., Baoding, 071051, China
| | - Shuiping Cheng
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
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Zhang N, Gao F, Cheng S, Xie H, Hu Z, Zhang J, Liang S. Mn oxides enhanced pyrene removal with both rhizosphere and non-rhizosphere microorganisms in subsurface flow constructed wetlands. CHEMOSPHERE 2022; 307:135821. [PMID: 35944687 DOI: 10.1016/j.chemosphere.2022.135821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 06/07/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
The polycyclic aromatic hydrocarbons (PAHs) are substantial wastewater pollutants emitted mostly by petroleum refineries and petrochemical industries, and their environmental fate has been of increasing concern among the public. Consequently, subsurface flow constructed wetlands (SFCWs) filled with Mn oxides (W-CW) or without Mn oxides (K-CW) were established to investigate the performance and mechanisms of pyrene (PYR) removal. The average removal rates of PYR in W-CW and K-CW were 96.00% and 92.33%, respectively. The PYR removal via other pathways (microbial degradation, photolysis, volatilisation, etc.) occupied a sizeable proportion, while the total PYR content in K-CW plant roots was significantly higher than that of W-CW. The microorganisms on the root surface and rhizosphere played an important role in PYR degradation in W-CW and K-CW and were higher in W-CW than that in K-CW in all matrix zones. The microorganisms between the 10-16 cm zone from the bottom of W-CW filled with Mn oxides (W-16) were positively correlated with PYR-degrading microorganisms, aerobic bacteria and facultative anaerobes, whereas K-16 without birnessite-coated sand was negatively correlated with these microorganisms.
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Affiliation(s)
- Ning Zhang
- Environment Research Institute, Shandong University, Jinan, 250100, China
| | - Fuwei Gao
- Zhongke Hualu Soil Remediation Engineering Co., Ltd, Dezhou, 253000, China
| | - Shiyi Cheng
- Jiangsu Ecological Environmental Monitoring Co., Ltd, Nanjing, 320100, China
| | - Huijun Xie
- Environment Research Institute, Shandong University, Jinan, 250100, China.
| | - Zhen Hu
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, Shandong, 250100, China
| | - Jian Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, Shandong, 250100, China; College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China
| | - Shuang Liang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, Shandong, 250100, China
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Seasonal Enhancement of Nitrogen Removal on Domestic Wastewater Treatment Performance by Partially Saturated and Saturated Hybrid Constructed Wetland. WATER 2022. [DOI: 10.3390/w14071089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study is to evaluate seasonal enhancement of nitrogen removal on domestic wastewater treatment performance by partially saturated and saturated HBCWs. To achieve this, two HBCWs consisting of a vertical subsurface flow constructed wetland, followed by a horizontal subsurface flow constructed wetland (VSSF-HSSF) were evaluated. Two saturation levels were used: (a) partially saturated HB1:VSSF1 (0.6 m)-HSSF1 (0.15 m), (b) saturated HB2: VSSF2 (0.8 m)-HSSF2 (0.25 m). Each unit was planted with Schoenoplectus californicus and was operated for 297 days. The removal efficiencies in HB1 and HB2 were above 70%, 86%, 77% and 55% for chemical oxygen demand (COD), total suspended solids (TSS), nitrogen as ammonium (NH4+-N), and total nitrogen (TN), respectively. For VSSF, a higher level of saturation (from 0.6 to 0.8 m) meant a decrease of 17% in the TN removal efficiencies, and for HSSF, an increase from 0.15 to 0.25 m of saturation meant a decrease of 11 and 10% in the NH4+-N and TN removal efficiencies, respectively. Thus, the increase of saturation level in HBCWs reduces the transformation and/or removal of components of the wastewaters to be treated, particularly nitrogen. Through this research, the possibility of optimizing the transformation of nitrogen with partially saturated hybrids can be examined.
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Gao F, Liu G, She Z, Ji J, Gao M, Zhao Y, Guo L, Jin C. Effects of salinity on pollutant removal and bacterial community in a partially saturated vertical flow constructed wetland. BIORESOURCE TECHNOLOGY 2021; 329:124890. [PMID: 33662852 DOI: 10.1016/j.biortech.2021.124890] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
This study investigated the influence of salinity on pollutant removal and bacterial community within a partially saturated vertical flow constructed wetland (PS-VFCW). High removal rates of NH4+-N (88.29 ± 4.97-100 ± 0%), total inorganic nitrogen (TIN) (50.00 ± 7.21-62.81 ± 7.21%) and COD (91.08 ± 2.66-100 ± 0%) were achieved at 0.4-2.4% salinity levels. The removal of ammonia, TIN and organic matter occurred mainly in unsaturated zone. Salt-adaptable microbes became the dominant bacteria with salinity elevated. The proportion of ammonia-oxidizing bacteria (AOB) in the 0-5 cm depth layer (unsaturated zone) decreased obviously as the salinity increased to 2.4%. Nitrite-oxidizing bacteria (NOB) in the 0-5 cm depth layer showed a decreasing trend with elevated salinity. Denitrifying bacteria (DNB) in the 0-5 cm depth layer maintained high abundance (27.70-53.60%) at 0.4-2.4% salinity levels. At 2.4% salinity, AOB, NOB and DNB were observed in the unsaturated zones and saturated zones, and showed higher abundance in the unsaturated zone.
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Affiliation(s)
- Feng Gao
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China
| | - Guochen Liu
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China
| | - Zonglian She
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China.
| | - Junyuan Ji
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China
| | - Mengchun Gao
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China
| | - Yangguo Zhao
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China
| | - Liang Guo
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China
| | - Chunji Jin
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, 266100 Qingdao, China; College of Environmental Science and Engineering, Ocean University of China, 266100 Qingdao, China
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Zheng X, Zhang J, Li M, Zhuang LL. Optimization of the pollutant removal in partially unsaturated constructed wetland by adding microfiber and solid carbon source based on oxygen and carbon regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:141919. [PMID: 32898802 DOI: 10.1016/j.scitotenv.2020.141919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/20/2020] [Accepted: 08/22/2020] [Indexed: 06/11/2023]
Abstract
The partially unsaturated constructed wetland was demonstrated to be able to enhance the oxygen supplement for the microbial nitrification. However, the fast gravity flow of wastewater on the smooth surface of substrate in unsaturated zone led to a short contact time between wastewater and biofilm on the surface of substrate for the microbial pollutant oxidation process. While, the strengthened oxygen supplement also consumed organic carbon, intensifying the shortage of electron donator for the denitrification process. To further enhance the efficiency of both nitrification and denitrification processes, two strategies were conducted as follows: (1) adding microfiber in unsaturated zone to extend the hydraulic retention time (HRT) and improve the oxygenating efficiency; (2) adding slow-release carbon source (Poly butylenes succinate, PBS) as electron donor in saturated zone for denitrification. Results showed that the ammonia oxidation efficiency reached up to 97.0% in the microfiber-enhanced constructed wetland. Additionally, adding microfiber provided more sites for microbes and increased the total number of microbes in unsaturated zone. The addition of PBS in the saturated zone obviously improved the denitrification efficiency with the total nitrogen (TN) removal rate raising from 20.6 ± 4.0% to 90.4 ± 2.7%, which excellently solved the problem of poor denitrification efficiency caused by low ratio of carbon to nitrogen (C/N). In conclusion, the association of microfiber and PBS in partially unsaturated constructed wetland finally accomplished the thorough nitrogen removal.
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Affiliation(s)
- Xinhui Zheng
- Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China.
| | - Jian Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao 266237, China.
| | - Mengting Li
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao 266237, China
| | - Lin-Lan Zhuang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao 266237, China.
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Zhang M, Chen C, Zhou S, Yang J, Qiu H, Zhao D, An S. Operation strategy for constructed wetlands in dry seasons with insufficient influent wastewater. BIORESOURCE TECHNOLOGY 2020; 317:124049. [PMID: 32871330 DOI: 10.1016/j.biortech.2020.124049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/14/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Using vertical flow constructed wetlands (VFCWs) with different influent wastewater volumes and feeding modes, this study aimed to identify the optimal operation strategy for dry seasons under wastewater deficiency. Using half the influent wastewater volume (HIWV) did not necessarily improve the removal efficiency (RE) of the chemical oxygen demand (COD), NH4+-N, NO3--N and total nitrogen. In the HIWV treatments, intermittent resting did not result in significantly different pollutant REs, whereas strategies involving partial saturation and prolongation of the hydraulic retention time (HRT) slightly decreased the pollutant REs compared with those obtained in the constant feeding mode. Of the three HIWV strategies, the intermittent resting mode achieved the highest anaerobic ammoxidation, the dominant pathway for nitrogen removal in the systems, and thus stimulated nitrogen transformation. The intermittent resting mode forms part of the recommended operation strategy for VFCWs in dry seasons with wastewater deficiency.
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Affiliation(s)
- Miao Zhang
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Chen Chen
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Shenyan Zhou
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Jiqiang Yang
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Han Qiu
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Dehua Zhao
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China.
| | - Shuqing An
- Institute of Wetland Ecology, School of Life Science, Nanjing University, Nanjing 210093, China
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