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Environmental dispersivity in free-water-surface-effect dominated wetland: multi-scale analysis

Zi WU, Zhi LI, Li ZENG, Ling SHAO, Hansong TANG, Qing YANG, Guoqian CHEN

《环境科学与工程前沿(英文)》 2011年 第5卷 第4期   页码 597-603 doi: 10.1007/s11783-011-0311-9

摘要: Distinct from the case with width-dominated shallow wetland flows, the longitudinal evolution of contaminant concentration in the most-typical pattern of wetland as dominated by free-water-surface-effect is characterized by a multi-scale analysis in the present study. An environmental dispersion model for the evolution of the mean concentration is deduced as an extension of Taylor's classical formulation by Mei’s multi-scale analysis. Corresponding environmental dispersivity is found identical to that determined by the method of concentration moments.

关键词: free-surface wetland     environmental dispersion     multi-scale analysis    

Dynamic analysis of free-surface thin film flows driven by gravity over undulated substrate

Zhaomiao LIU, Xin LIU, Guobin WANG, Hong LIAO,

《机械工程前沿(英文)》 2010年 第5卷 第2期   页码 219-225 doi: 10.1007/s11465-010-0010-4

摘要: This paper studies thin film flows with free surfaces driven by gravity through two types of undulated planes: periodically sinusoidal plane and triangle. The substrate plane is fixed and inclined to a certain angle and the flow with a free surface. Through finite element method (FEM), commenced from Navier-Stokes equations and continuity equation, the exact numerical results of free-surface film flows are obtained through discretization solution to finite equations in flowing areas. Based on the numerical calculations, the streamlines and wall shearing stress during the flowing process are visualized via post-proceeding, and the streamlines separation, the onset and evolution of vortex near the substrate boundary during the flow are also analyzed. The influences from the waviness of the substrate planes profile, height of the triangle plane, and change of the film height on film flow dynamics properties are shown.

关键词: waviness     triangle height     film thickness     streamlines separation     vortex    

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed

Juan WU, Jian ZHANG, Wenlin JIA, Huijun XIE, Bo ZHANG

《环境科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 241-247 doi: 10.1007/s11783-009-0023-6

摘要: The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N O) emissions, together with the relationships between N O and water quality parameters in free water surface constructed wetlands, were investigated with laboratory-scale systems. N O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N O emission in the system with middle COD influent concentration was the least. The relationships between N O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N O flux. The multiple linear regression model against principal components indicated that different water parameters affected N O flux with different COD concentrations in the influent, but nitrate nitrogen affected N O flux in all systems.

关键词: free water surface constructed wetland     nitrous oxide emission     water quality parameter     principal component analysis     multiple linear regression    

REDUCTION OF NON-POINT SOURCE POLLUTION IN THE YONG’AN RIVER BY CONSTRUCTED WETLAND BASED ON 9 YEARS

《农业科学与工程前沿(英文)》 2023年 第10卷 第4期   页码 627-638 doi: 10.15302/J-FASE-2023516

摘要:

The agricultural and livestock activities surrounding the rivers flowing into the lakes have caused non-point source pollution, leading to excessive amounts of nutrient salts in downstream rivers. Introducing river water into constructed wetlands along river course has proven to be an effective solution for decreasing nitrogen (N) and phosphorus (P) loads. This paper reports 9 years of monitoring the Yong’an River and its surrounding constructed wetlands in the upper reaches of Erhai Lake, located in Yunnan Province, China. This study analyzed the main types of pollutants in the river, and evaluated the removal efficiency of pollutants by the constructed wetlands. The findings indicate that total nitrogen (TN) and nitrate nitrogen (NO3-N) are the primary pollutants in the Yong’an River, which exhibit variation throughout the year corresponding to the alternating wet and dry seasons. Although constructed wetlands are effective in removing NO3-N and P, their efficacy in removing ammonium nitrogen (NH4+-N) and organic pollutants is limited. This limitation can be attributed to the lack of timely disposal of aquatic plant residues. This research contributes to the understanding of the potential issues that may arise during the extended use of constructed wetlands and provides solutions to address them.

关键词: inflowing rivers     surface-flow constructed wetland     nutrients     long-term monitoring    

Closed surface modeling with helical line measurement data

LI Ruqiong, LI Guangbu, WANG Yuhan

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 72-76 doi: 10.1007/s11465-007-0012-z

摘要: Models for surface modeling of free-form surface and massive data points are becoming an important feature in commercial computer aided design/computer-aided manufacturing software. However, there are many problems to be solved in this area, especially for closed free-form surface modeling. This article presents an effective method for cloud data closed surface modeling from asynchronous profile modeling measurement. It includes three steps: first, the cloud data are preprocessed for smoothing; second, a helical line is segmented to form triangle meshes; and third, Bezier surface patches are created over a triangle mesh and trimmed to shape on an entire surface. In the end, an illustrative example of shoe last surface modeling is given to show the availability of this method.

关键词: free-form surface     helical     triangle     design/computer-aided manufacturing     effective    

Effect of wetland plant fermentation broth on nitrogen removal and bioenergy generation in constructedwetland-microbial fuel cells

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1592-x

摘要:

● Fermentation broth facilitates N removal and energy yields in tertiary CW-MFC.

关键词: Constructed wetland     Microbial fuel cell     Nitrogen removal     Bioenergy generation     Carbon source    

Removal, distribution and plant uptake of perfluorooctane sulfonate (PFOS) in a simulated constructed wetland

Weichuan Qiao, Rong Li, Tianhao Tang, Achuo Anitta Zuh

《环境科学与工程前沿(英文)》 2021年 第15卷 第2期 doi: 10.1007/s11783-020-1312-3

摘要: Abstract • PFOS was removed by soil adsorption and plant uptake in the VFCW. • Uptake of PFOS by E. crassipes was more than that of C. alternifolius. • PFOS in wastewater can inhibit the removal of nutrients. • Dosing with PFOS changed the soil microbial community in the VFCW. A vertical-flow constructed wetland (VFCW) was used to treat simulated domestic sewage containing perfluorooctane sulfonate (PFOS). The removal rate of PFOS in the domestic sewage was 93%–98%, through soil adsorption and plant uptake, suggesting that VFCWs can remove PFOS efficiently from wastewater. The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake; moreover, the percentage of soil adsorption was 61%–89%, and was higher than that of the plants uptake (5%–31%). The absorption capacity of Eichhornia crassipes (E. crassipes) (1186.71 mg/kg) was higher than that of Cyperus alternifolius (C. alternifolius) (162.77 mg/kg) under 10 mg/L PFOS, and the transfer factor of PFOS in E. crassipes and C. alternifolius was 0.04 and 0.58, respectively, indicating that PFOS is not easily translocated to leaves from roots of wetland plants; moreover, uptake of PFOS by E. crassipes was more than that of C. alternifolius because the biomass of E. crassipes was more than that of C. alternifolius and the roots of E. crassipes can take up PFOS directly from wastewater while C. alternifolius needs to do so via its roots in the soil. The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen, total phosphorus, chemical oxygen demand, and ammonia nitrogen in the VFCW, which decreased by 15%, 10%, 10% and 12%, respectively. Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.

关键词: Vertical-flow constructed wetland     Perfluorooctane sulfonate     Wetland plants     Soil microbial community     Effect     Speciality: Wetlands     Transformation     Organic pollutants     Phytoremediation     Exposure assessment     Sewage    

Evaluating and structuring indicators for wetland assessment

Xuehua LIU, Yan SUN,

《环境科学与工程前沿(英文)》 2010年 第4卷 第2期   页码 221-227 doi: 10.1007/s11783-010-0029-0

摘要: Wetland assessment has been a popular field of research worldwide. However, various indicators have been used in wetland assessment for different purposes and backgrounds and also because of the research limitations. Therefore, a more comprehensive, sound, and efficient indicator system is needed for researchers’ referencing to evaluate wetlands. After an extensive review of wetland assessment literatures, the reported indicators were evaluated using the developed assessment system, based on the Analytical Hierarchy Process (AHP) with three main goals: nature protection, function utilization, and sustainable development. Each indicator was evaluated using two methods. The first method was to study the percentage of the indicator application, and the second was to assess the weighted ratios assigned to the indicators according to principles of comparability, typicality, sensibility, and availability. The results of these two methods were compared to study the commonalities and specialties of the indicators. They also showed that some indicators were widely used, including biodiversity, weather and climate, hydrological change, and the output of wetland. On the other hand, other sustainable indicators were easily ignored, such as environmental carrying capacity and wetland planning. Furthermore, an indicator system for wetland assessment was structured and strategized to discuss how to choose indicators for wetland assessment under different conditions. The proposed approach can be used to guide the process of wetland assessments in the future.

关键词: wetland assessment     indicators     Analytical Hierarchy Process (AHP)     comparison    

Translocation and biotoxicity of metal (oxide) nanoparticles in the wetland-plant system

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1432-4

摘要:

• Aquatic plants are more likely to absorb TiO2 NPs that are beneficial to them.

关键词: Constructed wetlands     Aquatic plants     Nanoparticles     Physiological activity     Biomass    

Towards Cr(VI)-free anodization of aluminum alloys for aerospace adhesive bonding applications: A review

Shoshan T. Abrahami, John M. M. de Kok, Herman Terryn, Johannes M. C. Mol

《化学科学与工程前沿(英文)》 2017年 第11卷 第3期   页码 465-482 doi: 10.1007/s11705-017-1641-3

摘要: For more than six decades, chromic acid anodizing (CAA) has been the central process in the surface pre-treatment of aluminum for adhesively bonded aircraft structures. Unfortunately, this electrolyte contains hexavalent chromium (Cr(VI)), a compound known for its toxicity and carcinogenic properties. To comply with the new strict international regulations, the Cr(VI)-era will soon have to come to an end. Anodizing aluminum in acid electrolytes produces a self-ordered porous oxide layer. Although different acids can be used to create this type of structure, the excellent adhesion and corrosion resistance that is currently achieved by the complete Cr(VI)-based process is not easily matched. This paper provides a critical overview and appraisal of proposed alternatives to CAA, including combinations of multiple anodizing steps, pre- and post anodizing treatments. The work is presented in terms of the modifications to the oxide properties, such as morphological features (e.g., pore size, barrier layer thickness) and surface chemistry, in order to evaluate the link between fundamental principles of adhesion and bond performance.

关键词: aluminum     Cr(VI)-free     surface pre-treatments     anodizing     adhesive bonding    

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting

F. H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

《机械工程前沿(英文)》 2017年 第12卷 第2期   页码 193-202 doi: 10.1007/s11465-017-0448-8

摘要:

Large-aperture potassium dihydrogen phosphate (KDP) crystals are widely used in the laser path of inertial confinement fusion (ICF) systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machining errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

关键词: ultra-precision fly cutting     large-aperture KDP crystals     spatial frequency     processing error    

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

Jianghua YU, Kisoo PARK, Youngchul KIM

《环境科学与工程前沿(英文)》 2012年 第6卷 第5期   页码 649-657 doi: 10.1007/s11783-012-0426-7

摘要: A stormwater wetland treating non-point source pollution (NPS) from a 64 ha agricultural watershed was monitored over a period of five months. The results indicated that pH and dissolved oxygen (DO) were increased in the wetland due to the algal growth. The highest total suspended solids (TSS) concentration was observed in the aeration pond due to the resuspension of solids, decreased in the wetland. The respective decreases in total nitrogen (TN) and total kjeldahl nitrogen (TKN) were 15.9% and 28.7% on passing through the wetland. The nitrate and ammonia were increased by 45.4% and decreased by 79.9%, respectively. These variations provided strong evidence for the existence of nitrification. The total phosphorus (TP) and phosphate had respective reductions of 52.3% and 58.2% over the wetland. The total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) were also decreased. Generally, the TN, TP and phosphate removal efficiencies were positive. These positive removal efficiencies were mainly due to microbial activities, uptake by plants, and chemical precipitation at high pH. Negative removal efficiencies can be caused by continuous rainfall activities, with short antecedent dry days (ADDs) and unstable hydraulic conditions, some other biogeochemical transformations and algal growth also being important parameters.

关键词: constructed stormwater wetland     dry days     nitrification and denitrification     pollutants characteristic    

Enhanced nitrogen removal reliability and efficiency in integrated constructed wetland microcosms using

Yue WEN, Chao XU, Gang LIU, Yi CHEN, Qi ZHOU

《环境科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 140-147 doi: 10.1007/s11783-011-0286-6

摘要: The purpose of this study is to reduce the seasonal fluctuation and enhance the efficiency of nitrogen removal in vertical flow-horizontal subsurface flow (VF-HSF) constructed wetlands. Two sets of VF-HSF constructed wetlands were built, VF1-HSF1 and VF2-HSF2, and a zeolite section was placed in VF2. The results showed that VF2-HSF2 compared to VF1-HSF1 was not only a more reliable nitrogen removal method, but also enhanced the nitrogen removal efficiency by 50%. The average apparent rate of nitrogen removal in VF2-HSF2 reached to 2.52 gN·m ·d , which doubled the rate in VF1-HSF1. Plant uptake and organic nitrogen sediment accounted for 12% and 6% of the total nitrogen removal in VF1-HSF1, respectively, and 10% and 4% in VF2-HSF2, respectively. Biologic nitrogen removal was the dominant mechanism, which accounted for 79% and 87% of the total nitrogen removal in VF1-HSF1 and VF2-HSF2, respectively. Ammonia adsorbed by zeolite during the cold seasons was desorbed, and then nitrified in warm seasons, which resulted in a bioregeneration efficiency of 91%. Zeolite in VF was capable of transferring ammonia from cold seasons to warm seasons as well as enhancing nitrification, which was accompanied by high potential denitrification in HSF that reinforced the efficiency and relieved seasonal fluctuation of nitrogen removal in VF-HSF.

关键词: constructed wetland     zeolite     bioregeneration     nitrogen removal    

EMERGY analysis for sustainability evaluation of the Baiyangdian wetland ecosystem in China

Weiqing MENG, Cui HAO, Hongyuan LI, Meiting JU,

《环境科学与工程前沿(英文)》 2010年 第4卷 第2期   页码 203-212 doi: 10.1007/s11783-010-0015-6

摘要: This study presents a quantitative and ecological benefit evaluation of the Baiyangdian wetland in China between the years 2000 and 2006. Methods of EMERGY analysis were applied to illustrate the wetland ecosystem, to evaluate the economic and environmental inputs and consequent yields, and to assess the sustainability of the Baiyangdian wetland. The indicators for the integrated ecological and economic system, such as EMERGY yield ratio (EYR) (7.51), EMERGY investment ratio (EIR) (4.52), environmental loading ratio (ELR) (2.92), EMERGY exchange ratio (0.41), and EMERGY sustainable indicator (ESI) (2.57) were calculated, compared, analyzed, and discussed. The non-renewable investment in Baiyangdian was greater than renewable investment, leading to the unsustainable development of the system. High EYR indicated that the Baiyangdian integrated system had created huge profits for its people, while ELR and ESI revealed that human behavior has been a heavy burden on the environment, and countermeasures should be taken by the Chinese government to relieve and resolve these problems. Potential management methods were also proposed in this paper.

关键词: EMERGY analysis     sustainability     wetland ecosystem     indicators    

Cadmium tolerance and accumulation in fifteen wetland plant species from cadmium-polluted water in constructed

Jianguo LIU,Wen ZHANG,Peng QU,Mingxin WANG

《环境科学与工程前沿(英文)》 2016年 第10卷 第2期   页码 262-269 doi: 10.1007/s11783-014-0746-x

摘要: Variations in cadmium (Cd) tolerances and accumulations among fifteen wetland plant species in moderately (0.5 mg·L ) and heavily (1.0 mg·L ) Cd-polluted wastewaters were investigated in constructed wetlands. Cd removal efficiencies from the wastewaters were more than 90%, and 23.5% and 16.8% of the Cd in the water accumulated in wetland plants for 0.5 and 1.0 mg·L Cd treatments, respectively. The variations among the plant species were 29.4-fold to 48.7-fold in plant biomasses, 5.4-fold to 21.9-fold in Cd concentrations, and 13.8-fold to 29.6-fold in Cd accumulations. The plant species were also largely diversified in terms of Cd tolerance. Some species were tolerant of heavy Cd stress, and some others were sensitive to moderate Cd level. Four wetland plant species were selected for the treatment of Cd-polluted wastewater for their high Cd accumulating abilities and relative Cd tolerances. Plant Cd quantity accumulations are correlated positively and significantly ( <0.05) with plant biomasses and correlated positively but insignificantly ( >0.05) with plant Cd concentrations. The results indicate that the Cd accumulation abilities of wetland plant species are determined mainly by their biomasses and Cd tolerances in growth, which should be the first criteria in selecting wetland plant species for the treating Cd-polluted wastewaters. Cd concentration in the plants may be the second consideration.

关键词: cadmium (Cd)     wastewater treatment     wetland plant     selection     index    

标题 作者 时间 类型 操作

Environmental dispersivity in free-water-surface-effect dominated wetland: multi-scale analysis

Zi WU, Zhi LI, Li ZENG, Ling SHAO, Hansong TANG, Qing YANG, Guoqian CHEN

期刊论文

Dynamic analysis of free-surface thin film flows driven by gravity over undulated substrate

Zhaomiao LIU, Xin LIU, Guobin WANG, Hong LIAO,

期刊论文

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed

Juan WU, Jian ZHANG, Wenlin JIA, Huijun XIE, Bo ZHANG

期刊论文

REDUCTION OF NON-POINT SOURCE POLLUTION IN THE YONG’AN RIVER BY CONSTRUCTED WETLAND BASED ON 9 YEARS

期刊论文

Closed surface modeling with helical line measurement data

LI Ruqiong, LI Guangbu, WANG Yuhan

期刊论文

Effect of wetland plant fermentation broth on nitrogen removal and bioenergy generation in constructedwetland-microbial fuel cells

期刊论文

Removal, distribution and plant uptake of perfluorooctane sulfonate (PFOS) in a simulated constructed wetland

Weichuan Qiao, Rong Li, Tianhao Tang, Achuo Anitta Zuh

期刊论文

Evaluating and structuring indicators for wetland assessment

Xuehua LIU, Yan SUN,

期刊论文

Translocation and biotoxicity of metal (oxide) nanoparticles in the wetland-plant system

期刊论文

Towards Cr(VI)-free anodization of aluminum alloys for aerospace adhesive bonding applications: A review

Shoshan T. Abrahami, John M. M. de Kok, Herman Terryn, Johannes M. C. Mol

期刊论文

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting

F. H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

期刊论文

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

Jianghua YU, Kisoo PARK, Youngchul KIM

期刊论文

Enhanced nitrogen removal reliability and efficiency in integrated constructed wetland microcosms using

Yue WEN, Chao XU, Gang LIU, Yi CHEN, Qi ZHOU

期刊论文

EMERGY analysis for sustainability evaluation of the Baiyangdian wetland ecosystem in China

Weiqing MENG, Cui HAO, Hongyuan LI, Meiting JU,

期刊论文

Cadmium tolerance and accumulation in fifteen wetland plant species from cadmium-polluted water in constructed

Jianguo LIU,Wen ZHANG,Peng QU,Mingxin WANG

期刊论文