Performance of A2O combined with constructed wetland on treating rural domestic sewage in plain areas of Yangtze River delta region, China
XIA Bin1,2,, SHENG Xiaolin2, XU Feng3, SHI Junyuan3, HUANG Zhaowei1,2, LIU Rui2,, 1.School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai 200030, China 2.Department of Environment in Yangtze Delta Region Institute of Tsinghua University, Zhejiang Provincial Key Laboratory of Water Science and Technology, Jiaxing 314006, China 3.Bureau of Housing and Urban-Rural Development of Jiaxing, Jiaxing 314000, China
Abstract:Samples from 28 A2O combined with horizontal flow constructed wetlands (A2O-HFCWs) and 46 A2O combined with vertical flow constructed wetlands (A2O-VFCWs) in Haining County, Jiaxing City were collected, chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphorus (TP) and suspended solids (SS) in the influent and effluent were determined. Then the stability of effluent quality and compliance rate were evaluated, the comparisons between these two processes on the performance of rural domestic sewage treatment, and the problems of design and operation, were conducted. The results showed that: The compliance rates of A2O-VFCWs were higher than those of A2O-HFCWs.The effluent stability of A2O-VFCWs was good in winter, but poor in summer. The average removal rates of COD, NH3-N, TN and TP by A2O+VFCWs were (82.0±18.5)%, (94.8±8.8)%, (49.3±16.8)%, and (50.9±16.8)% in winter, respectively, while they were (72.5±13.2)%, (80.0±16.9)%, (30.0±17.8)%, and (30.7±18.9) % in summer, respectively. The main unit being responsible for pollutants removal was VFCWs. For A2O+HFCWs, the average removal rates of COD, NH3-N, TN and TP by A2O+VFCWs were (59.3±21.4)%, (79.1±19.9)%, (42.3±17.3)% and (25.0±10.2)% in winter, respectively,, while they were (62.2±18.0)%, (58.1±30.8)%, (40.6±20.0)% and (28.9±15.7)% in summer, respectively. The main unit being responsible for pollutants removal was A2O. The average TN and TP removal rates of A2O unit in A2O+VFCWs were (20.7±16.3)% and (15.6±10.2)% in winter, (20.4±11.9)% and (12.6±13.9)% in summer, respectively, which were significantly lower than those of A2O unit in A2O+HFCWs: (33.2±16.3)% and (25.0±10.2)% in winter, (31.3±24.1)% and (21.9±17.4)% in summer, respectively, The reason was the small effective volume and insufficient dissolved oxygen control. The removal efficiencies of A2O unit in these two combined processes were not ideal, which may be related to the low ratio of carbon to nitrogen and insufficient sludge discharge. The average removal rates of COD, NH3-N, TN and TP of VFCWs unit in A2O+VFCWs were (58.8±25.4)%, (61.4±24.4)%, (22.7±8.5)%, and (27.4±21.2)% in winter, which were 16.0%, 36.9%, 1.3%, and 9.5% higher than those of HFCWs, respectively; they were (59.9±25.0)%, (71.6±26.5)%, (38.3±32.8)%, and (39.2±32.9)% in summer, which were 28.8%, 52.6%, 10.5%, and 5.0% higher than those of HFCWs, respectively. The main reasons were the lower design hydraulic load and lower outlet level of VFCWs. To sum up, the county-level city was suggested to improve the performance of A2O or constructed wetland by upgrading structure of the units and optimizing operation strategies. Key words:rural domestic sewage/ A2O/ horizontal flow constructed wetland/ vertical flow constructed wetland/ nitrogen and phosphorus removal.
图12种组合工艺流程图 Figure1.Flow chart of two combination processes
图2稳定达标率、稳定达标率系数与不同变异系数的关系 Figure2.Dependence of the standard compliance rate and the coefficient of the standard compliance rate on the variation coefficient
图42种组合工艺的A2O与人工湿地单元在冬夏两季的污染物去除占比 Figure4.Pollutant removal ratio of A2O and constructed wetland units in the two combined processes in winter and summer
表12种组合工艺的冬季和夏季水质 Table1.Water quality of the two combined processes in winter and summer
季节
工艺类型
抽检设施/座
沿程水质
NH3-N/(mg?L?1)
TN/(mg?L?1)
TP/(mg?L?1)
COD/(mg?L?1)
SS/(mg?L?1)
冬季
A2O+HFCWs
16
A2O进水
28.4±14.1
38.4±19.1
2.7±1.2
40.7±29.6
15.4±15.0
A2O出水
13.6±12.2
26.0±12.8
2.3±1.1
30.2±26.3
16.6±23.2
湿地出水
6.8±7.5
20.4±9.1
2.0±0.9
16.1±9.2
9.6±19.0
A2O+VFCWs
8
A2O进水
36.2±27.1
46.6±28.8
3.7±2.8
45.8±44.2
107.4±189.7
A2O出水
31.4±26.9
40.0±24.2
3.2±2.2
44.1±41.5
16.1±24.0
湿地出水
4.0±3.1
33.1±21.4
1.9±0.9
12.8±2.9
13.1±17.3
夏季
A2O+HFCWs
29
A2O进水
45.2±17.3
53.4±18.6
5.1±1.8
144.8±64.3
94.0±44.4
A2O出水
25.1±20.6
41.3±20.0
4.3±1.6
64.7133.8
33.4±16.0
湿地出水
24.0±19.0
35.7±19.3
3.8±1.5
53.0±29.5
27.0±19.4
A2O+VFCWs
21
A2O进水
38.2±27.3
46.6±27.0
4.9±2.9
102.8±84.2
68.9±61.2
A2O出水
32.1±26.2
40.9±36.4
4.3±2.7
99.5±132.9
49.3±43.5
湿地出水
11.3±17.0
36.4±21.5
3.9±2.5
28.0±24.3
17.8±17.6
季节
工艺类型
抽检设施/座
沿程水质
NH3-N/(mg?L?1)
TN/(mg?L?1)
TP/(mg?L?1)
COD/(mg?L?1)
SS/(mg?L?1)
冬季
A2O+HFCWs
16
A2O进水
28.4±14.1
38.4±19.1
2.7±1.2
40.7±29.6
15.4±15.0
A2O出水
13.6±12.2
26.0±12.8
2.3±1.1
30.2±26.3
16.6±23.2
湿地出水
6.8±7.5
20.4±9.1
2.0±0.9
16.1±9.2
9.6±19.0
A2O+VFCWs
8
A2O进水
36.2±27.1
46.6±28.8
3.7±2.8
45.8±44.2
107.4±189.7
A2O出水
31.4±26.9
40.0±24.2
3.2±2.2
44.1±41.5
16.1±24.0
湿地出水
4.0±3.1
33.1±21.4
1.9±0.9
12.8±2.9
13.1±17.3
夏季
A2O+HFCWs
29
A2O进水
45.2±17.3
53.4±18.6
5.1±1.8
144.8±64.3
94.0±44.4
A2O出水
25.1±20.6
41.3±20.0
4.3±1.6
64.7133.8
33.4±16.0
湿地出水
24.0±19.0
35.7±19.3
3.8±1.5
53.0±29.5
27.0±19.4
A2O+VFCWs
21
A2O进水
38.2±27.3
46.6±27.0
4.9±2.9
102.8±84.2
68.9±61.2
A2O出水
32.1±26.2
40.9±36.4
4.3±2.7
99.5±132.9
49.3±43.5
湿地出水
11.3±17.0
36.4±21.5
3.9±2.5
28.0±24.3
17.8±17.6
下载: 导出CSV 表22种组合工艺出水在冬夏两季的稳定达标率与偏差系数 Table2.Stable compliance rates and deviation coefficients of effluents from the two combined processes in winter and summer
DRIZO A, FROST C A, GRACE J, et al. Physico-chemical screening of phosphate-removing substrates for use in constructed wetland systems[J]. Water Research, 1999, 33(17): 3595-3602. doi: 10.1016/S0043-1354(99)00082-2
YU G, PENG H, FU Y, et al. Enhanced nitrogen removal of low c/n wastewater in constructed wetlands with co-immobilizing solid carbon source and denitrifying bacteria[J]. Bioresource Technology, 2019, 280: 337-344. doi: 10.1016/j.biortech.2019.02.043
NIKU S, SCHROEDER E D, SAMANIEGO F J. Performance of activated sludge processes and reliability-based design[J]. Journal (Water Pollution Control Federation), 1979, 51(12): 2841-2857.
áVILA C, MATAMOROS V, REYES-CONTRERAS C, et al. Attenuation of emerging organic contaminants in a hybrid constructed wetland system under different hydraulic loading rates and their associated toxicological effects in wastewater[J]. Science of the Total Environment, 2014, 470-47: 1272-1280.
[18]
DECEZARO S T, WOLFF D B, PELISSARI C, et al. Influence of hydraulic loading rate and recirculation on oxygen transfer in a vertical flow constructed wetland[J]. Science of the Total Environment, 2019, 668: 988-995. doi: 10.1016/j.scitotenv.2019.03.057
LU S, GAO X, WU P, et al. Assessment of the treatment of domestic sewage by a vertical-flow artificial wetland at different operating water levels[J]. Journal of Cleaner Production, 2019, 208: 649-655. doi: 10.1016/j.jclepro.2018.10.111
WANG R, ZHAO X, LIU H, et al. Elucidating the impact of influent pollutant loadings on pollutants removal in agricultural waste-based constructed wetlands treating low C/N wastewater[J]. Bioresource Technology, 2019, 273: 529-537. doi: 10.1016/j.biortech.2018.11.044
ZHENG X, JIN M, ZHOU X, et al. Enhanced removal mechanism of iron carbon micro-electrolysis constructed wetland on C, N, and P in salty permitted effluent of wastewater treatment plant[J]. Science of the Total Environment, 2019, 649: 21-30. doi: 10.1016/j.scitotenv.2018.08.195
[34]
GE Z, WEI D, ZHANG J, et al. Natural pyrite to enhance simultaneous long-term nitrogen and phosphorus removal in constructed wetland: Three years of pilot study[J]. Water Research, 2019, 148: 153-161. doi: 10.1016/j.watres.2018.10.037
1.School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai 200030, China 2.Department of Environment in Yangtze Delta Region Institute of Tsinghua University, Zhejiang Provincial Key Laboratory of Water Science and Technology, Jiaxing 314006, China 3.Bureau of Housing and Urban-Rural Development of Jiaxing, Jiaxing 314000, China Received Date: 2020-02-19 Accepted Date: 2020-05-09 Available Online: 2021-01-13 Keywords:rural domestic sewage/ A2O/ horizontal flow constructed wetland/ vertical flow constructed wetland/ nitrogen and phosphorus removal Abstract:Samples from 28 A2O combined with horizontal flow constructed wetlands (A2O-HFCWs) and 46 A2O combined with vertical flow constructed wetlands (A2O-VFCWs) in Haining County, Jiaxing City were collected, chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphorus (TP) and suspended solids (SS) in the influent and effluent were determined. Then the stability of effluent quality and compliance rate were evaluated, the comparisons between these two processes on the performance of rural domestic sewage treatment, and the problems of design and operation, were conducted. The results showed that: The compliance rates of A2O-VFCWs were higher than those of A2O-HFCWs.The effluent stability of A2O-VFCWs was good in winter, but poor in summer. The average removal rates of COD, NH3-N, TN and TP by A2O+VFCWs were (82.0±18.5)%, (94.8±8.8)%, (49.3±16.8)%, and (50.9±16.8)% in winter, respectively, while they were (72.5±13.2)%, (80.0±16.9)%, (30.0±17.8)%, and (30.7±18.9) % in summer, respectively. The main unit being responsible for pollutants removal was VFCWs. For A2O+HFCWs, the average removal rates of COD, NH3-N, TN and TP by A2O+VFCWs were (59.3±21.4)%, (79.1±19.9)%, (42.3±17.3)% and (25.0±10.2)% in winter, respectively,, while they were (62.2±18.0)%, (58.1±30.8)%, (40.6±20.0)% and (28.9±15.7)% in summer, respectively. The main unit being responsible for pollutants removal was A2O. The average TN and TP removal rates of A2O unit in A2O+VFCWs were (20.7±16.3)% and (15.6±10.2)% in winter, (20.4±11.9)% and (12.6±13.9)% in summer, respectively, which were significantly lower than those of A2O unit in A2O+HFCWs: (33.2±16.3)% and (25.0±10.2)% in winter, (31.3±24.1)% and (21.9±17.4)% in summer, respectively, The reason was the small effective volume and insufficient dissolved oxygen control. The removal efficiencies of A2O unit in these two combined processes were not ideal, which may be related to the low ratio of carbon to nitrogen and insufficient sludge discharge. The average removal rates of COD, NH3-N, TN and TP of VFCWs unit in A2O+VFCWs were (58.8±25.4)%, (61.4±24.4)%, (22.7±8.5)%, and (27.4±21.2)% in winter, which were 16.0%, 36.9%, 1.3%, and 9.5% higher than those of HFCWs, respectively; they were (59.9±25.0)%, (71.6±26.5)%, (38.3±32.8)%, and (39.2±32.9)% in summer, which were 28.8%, 52.6%, 10.5%, and 5.0% higher than those of HFCWs, respectively. The main reasons were the lower design hydraulic load and lower outlet level of VFCWs. To sum up, the county-level city was suggested to improve the performance of A2O or constructed wetland by upgrading structure of the units and optimizing operation strategies.
下载: 
点击查看大图
