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Special Issue "Constructed Wetlands Systems and Management"

A special issue of Water (ISSN 2073-4441).

Deadline for manuscript submissions: closed (29 February 2016)

Special Issue Editors

Guest Editor
Dr. Alan Howard

Department of Geography and Environmental Science University of Reading , Reading, RG6 6AB, UK
Website | E-Mail
Interests: constructed wetlands; cyanobacteria; water resource management; computer
Guest Editor
Prof. Dr. Defu Xu

School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China
Website | E-Mail
Phone: +86 025 5869 5684
Fax: +86 025 5869 5684
Interests: wetland plants; substrate; enzyme; clogging; purifying capacity; nitrogen; phosphorus

Special Issue Information

Dear Colleagues,

The use of constructed wetland systems for purifying wastewater is an area of increasing importance in water resources management. Such systems typically include a combination of substrate, wetland plants, microorganisms, and fauna, such as earthworms. Efficiency of operation depends on composition and is variable over time due to reduced purifying capacity of constituents, changes in dissolved oxygen and susceptibility to clogging of the constucted wetland system. Therefore, the design and management of constructed wetland systems is very important in maintaining purifying capacity and system sustainability. This Special Issue of Water will bring together current knowledge of the design, operation and management of constructed wetland systems. The Special Issue will help inform the future development and implementation of effective constructed wetlands.

Dr. Alan Howard
Prof. Dr. Defu Xu
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • constructed wetlands
  • wastewater
  • wetland plants
  • water resources management
  • purification

Published Papers (9 papers)

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Research

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Open AccessArticle Flume Experiments for Optimizing the Hydraulic Performance of a Deep-Water Wetland Utilizing Emergent Vegetation and Obstructions
Water 2016, 8(6), 265; doi:10.3390/w8060265
Received: 23 March 2016 / Revised: 10 June 2016 / Accepted: 17 June 2016 / Published: 21 June 2016
Cited by 2 | PDF Full-text (3467 KB) | HTML Full-text | XML Full-text
Abstract
Constructed ponds and wetlands are widely used in urban areas for stormwater management, ecological conservation, and pollution treatment. The treatment efficiency of these systems is strongly related to the hydrodynamics and hydraulic residence time. In this study, we developed a physical model and
[...] Read more.
Constructed ponds and wetlands are widely used in urban areas for stormwater management, ecological conservation, and pollution treatment. The treatment efficiency of these systems is strongly related to the hydrodynamics and hydraulic residence time. In this study, we developed a physical model and used rhodamine-WT as a tracer to conduct flume experiments. An equivalent Reynolds number was assumed, and the flume was a 1/25-scale model. Emergent obstructions (EOs), submerged obstructions (SOs), and high- and low-density emergent vegetation were placed along the sides of the flume, and 49 tracer tests were performed. We altered the density, spatial extent, aspect ratio, and configurations of the obstructions and emergent vegetation to observe changes in the hydraulic efficiency of a deep-water wetland. In the cases of low-aspect-ratio obstructions, the effects of the EOs on the hydraulic efficiency were significantly stronger than those of the SOs. In contrast, in the cases of high-aspect-ratio obstructions, the improvement effects of the EOs were weaker than those of the SOs. The high-aspect-ratio EOs altered the flow direction and constrained the water conveyance area, which apparently caused a short-circuited flow phenomenon, resulting in a decrease in hydraulic efficiency. Most cases revealed that the emergent vegetation improved the hydraulic efficiency more than the EOs. The high-density emergent vegetation (HEV) improved the hydraulic efficiency more than the low-density emergent vegetation (LEV). Three cases involving HEV, two cases involving LEV, and one case involving EOs attained a good hydraulic efficiency (λ > 0.75). To achieve greater water purification, aquatic planting in constructed wetlands should not be overly dense. The HEV configuration in case 3-1 achieved optimum hydraulic performance for compliance with applicable water treatment standards. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle Evaluation of Phytodesalination Potential of Vegetated Bioreactors Treating Greenhouse Effluent
Water 2016, 8(6), 233; doi:10.3390/w8060233
Received: 25 February 2016 / Revised: 9 May 2016 / Accepted: 23 May 2016 / Published: 31 May 2016
Cited by 1 | PDF Full-text (2643 KB) | HTML Full-text | XML Full-text
Abstract
The dissolved salt ions that are not absorbed during irrigation of greenhouse crops are gradually accumulated in the nutrient solution resulting in levels of salinity high enough to damage the crops. This water salinity presents operational and environmental challenges as the nutrient-rich greenhouse
[...] Read more.
The dissolved salt ions that are not absorbed during irrigation of greenhouse crops are gradually accumulated in the nutrient solution resulting in levels of salinity high enough to damage the crops. This water salinity presents operational and environmental challenges as the nutrient-rich greenhouse effluent should be discharged to the environment when deemed unsuited for irrigation. In this pilot-scale study, the potential of passive salt reduction (phytodesalination) in gravel and wood-chip flow-through reactors was evaluated using seven plant species including Schoenoplectus tabernaemontani, Andropogon gerardii, Typha angustifolia, Elymus canadensis, Panicum virgatum, Spartina pectinata and Distichlis spicata along with an unplanted control reactor. While the unplanted system outperformed the planted units with gravel media, the wood-chip bioreactors with S. tabernaemontani and S. pectinata improved the greenhouse effluent reducing the solution conductivity (EC) by a maximum of 15% (average = 7%). S. tabernaemontani and D. spicata showed higher accumulated contents of Na+ and Cl in comparison with T. angustifolia and S. pectinata. Overall, S. tabernaemontani was selected as the most capable species in the wood-chip bioreactors for its better salt management via EC reduction and salt accumulation. It was however concluded that further treatment would be required for the greenhouse effluent to meet the stringent irrigation water quality guidelines in order not to pose any adverse effects on sensitive crops. Finally, the present hydraulic residence time (HRT = 3.7 days) and the solution salinity concentration were identified as the potential factors that may be limiting the efficiency of plant salt uptake, emphasizing the need for conducting more research on the optimization and enhancement of passive desalination systems for the greenhouse effluent. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle Performance of a Constructed Wetland and Pretreatment System Receiving Potato Farm Wash Water
Water 2016, 8(5), 183; doi:10.3390/w8050183
Received: 28 February 2016 / Revised: 15 April 2016 / Accepted: 26 April 2016 / Published: 29 April 2016
Cited by 3 | PDF Full-text (1742 KB) | HTML Full-text | XML Full-text
Abstract
Many potato processors require on-farm washing of potatoes, creating large quantities of wastewater that requires treatment, starting in the fall until the end of the potato storage period in mid-summer. We studied the treatment of wastewater from a potato farm in Ontario, Canada,
[...] Read more.
Many potato processors require on-farm washing of potatoes, creating large quantities of wastewater that requires treatment, starting in the fall until the end of the potato storage period in mid-summer. We studied the treatment of wastewater from a potato farm in Ontario, Canada, using a system of pretreatment (sedimentation, aeration) followed by a surface-flow wetland with a dense growth of cattails (Typha sp.). The raw wastewater had high average concentrations of 5-day biochemical oxygen demand (BOD5; 1113 mg·L−1), total suspended solids (TSS; 4338 mg·L−1), total nitrogen (TN; 311 mg·L−1) and total phosphorus (TP; 42.5 mg·L−1). Due to high influent loads, the pretreatment was enlarged during annual sediment cleaning at the end of Year 1 (Y1), which increased the hydraulic retention time and delayed the seasonal onset of wetland loading from winter in Y1 to spring in Year 2 (Y2). Total concentration reduction for the treatment system (pretreatment + wetland) in Y2 was 96% BOD5, 99% TSS, 86% TN and 90% TP; and in Y1 was 79% BOD5, 97% TSS, 62% TN and 54% TP. Overall, the best treatment in both the pretreatment and the wetland was seen in spring months. The enlarged pretreatment system enabled seasonal loading of the wetland during the spring and summer, which facilitated improved treatment performance. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle Decline in Performance of Biochemical Reactors for Sulphate Removal from Mine-Influenced Water is Accompanied by Changes in Organic Matter Characteristics and Microbial Population Composition
Water 2016, 8(4), 124; doi:10.3390/w8040124
Received: 1 February 2016 / Revised: 18 March 2016 / Accepted: 22 March 2016 / Published: 30 March 2016
Cited by 2 | PDF Full-text (2371 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Successful long-term bioremediation of mining-influenced water using complex organic matter and naturally-occurring microorganisms in sub-surface flow constructed wetlands requires a balance between easily and more slowly degrading material. This can be achieved by combining different types of organic materials. To provide guidance on
[...] Read more.
Successful long-term bioremediation of mining-influenced water using complex organic matter and naturally-occurring microorganisms in sub-surface flow constructed wetlands requires a balance between easily and more slowly degrading material. This can be achieved by combining different types of organic materials. To provide guidance on what mixture combinations to use, information is needed on how the ratio of labile to recalcitrant components affects the degradation rate and the types of microbial populations supported. To investigate this, different ratios of wood and hay were used in up-flow column bioreactors treating selenium- and sulphate-containing synthetic mine-influenced water. The degradation rates of crude fibre components appeared to be similar regardless of the relative amounts of wood and hay. However, the nature of the degradation products might have differed in that those produced in the hay-rich bioreactors were more biodegradable and supported high sulphate-reduction rates. Microorganisms in the sulphate-reducing and cellulose-degrading inocula persisted in the bioreactors indicating that bio-augmentation was effective. There was a shift in microbial community composition over time suggesting that different microbial groups were involved in decomposition of more recalcitrant material. When dissolved organic carbon (DOC) was over-supplied, the relative abundance of sulphate-reducers was low even through high sulphate-reduction rates were achieved. As DOC diminished, sulphate-reducers become more prevalent and their relative abundance correlated with sulphate concentrations rather than sulphate-reduction rate. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Figures

Open AccessArticle Salts Removal from Synthetic Solution-Potash Brine by Non-Planted Constructed Wetlands
Water 2016, 8(4), 113; doi:10.3390/w8040113
Received: 8 February 2016 / Revised: 13 March 2016 / Accepted: 21 March 2016 / Published: 24 March 2016
Cited by 2 | PDF Full-text (1215 KB) | HTML Full-text | XML Full-text
Abstract
Four pilot-scale non-planted constructed wetlands (CWs) were employed to study the fate and transport of the two dominant chloride salts contained in brine resulting from solution mining activities in the potash industry. The simulated brine contained a 10:1 ratio of NaCl:KCl based on
[...] Read more.
Four pilot-scale non-planted constructed wetlands (CWs) were employed to study the fate and transport of the two dominant chloride salts contained in brine resulting from solution mining activities in the potash industry. The simulated brine contained a 10:1 ratio of NaCl:KCl based on authentic brine characteristics. The multi-layer soils functioned as a main salt filtering component comprising of Regina Clay, sand and gravels. The CW systems were operated in three batches of 16 days (experiments 1–3). K+ ions were removed by 92% (4.6 mg/L) from the effluent, while Cl and Na+ were removed in lower proportions of 51% (85.3 mg/L) and 45% (53.2 mg/L), respectively. Over time, the retained quantities of the three target salt ions decreased, indicating that clay sorption capacity may have been reached. This study demonstrated that Regina Clay has substantial sorbent capacity for salt ions contained in simulated potash brine solution. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle The Potential Growth of Sugarcane in Constructed Wetlands Designed for Tertiary Treatment of Wastewater
Water 2016, 8(3), 93; doi:10.3390/w8030093
Received: 25 January 2016 / Revised: 25 February 2016 / Accepted: 4 March 2016 / Published: 10 March 2016
PDF Full-text (2485 KB) | HTML Full-text | XML Full-text
Abstract
This research was conducted to evaluate the feasibility of using the bioenergy crop Saccharum officinarum (sugarcane) as vegetation and mineral wastes for filling in constructed wetlands (CWs) designed for the removal of nutrients from wastewater. Four horizontal subsurface flow pilot-scale CWs were monitored
[...] Read more.
This research was conducted to evaluate the feasibility of using the bioenergy crop Saccharum officinarum (sugarcane) as vegetation and mineral wastes for filling in constructed wetlands (CWs) designed for the removal of nutrients from wastewater. Four horizontal subsurface flow pilot-scale CWs were monitored during one year: two filled with fragmented limestone and two with clay brick fragments, two planted and two unplanted controls. Sugarcane stalk height, diameter and foliar area were evaluated during the plant-cane cycle along with total phosphorus (TP) and total nitrogen (TN) removal efficiencies from the wastewater. Sugarcane biomass production was 107 ton/ha for the brick fragments filled CW and 67 ton/ha for the fragmented limestone filled CW. Planted CWs show better nutrient removal efficiencies than the unplanted. Planted CW filled with brick fragments show average efficiencies of 77% ± 4% for TP and 60% ± 12% for TN, and planted CW filled with fragmented limestone 68% ± 3% for TP and 58% ± 7% for TN. Results showed that the use of sugarcane as CW vegetation is a viable alternative to produce a bioethanol raw-material without the use of arable land and irrigation water, while it maintains the wastewater treatment capabilities of CWs. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle Efficiency of a Horizontal Sub-Surface Flow Constructed Wetland Treatment System in an Arid Area
Water 2016, 8(2), 51; doi:10.3390/w8020051
Received: 30 November 2015 / Revised: 25 January 2016 / Accepted: 1 February 2016 / Published: 5 February 2016
PDF Full-text (807 KB) | HTML Full-text | XML Full-text
Abstract
The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW) in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the
[...] Read more.
The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW) in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the quality of partially-treated municipal wastewater. The studied design parameters included two sizes of volcanic tuff media (i.e., fine or coarse), two different bed dimensions (i.e., long and short), and three plantation types (i.e., reed, kenaf, or no vegetation as a control). The effluent Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), and phosphorus from all of the treatments were significantly lower as compared to the influent and demonstrated a removal efficiency of 55%, 51%, 67%, and 55%, respectively. There were significant increases in Electrical Conductivity (EC), sulfate, and calcium in the effluent of most HSF-CWs due to evaporative concentration and mineral dissolution from the media. The study suggests that unplanted beds with either fine or coarse media are the most suitable combinations among all of the studied designs based on their treatment efficiency and less water loss in arid conditions. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)
Open AccessArticle Effect of Plant Harvesting on the Performance of Constructed Wetlands during Summer
Water 2016, 8(1), 24; doi:10.3390/w8010024
Received: 24 November 2015 / Revised: 24 December 2015 / Accepted: 8 January 2016 / Published: 16 January 2016
Cited by 4 | PDF Full-text (721 KB) | HTML Full-text | XML Full-text
Abstract
Plants can remove pollutants through direct absorption and by providing habitats for microbes to stimulate their activities. The aboveground plant biomass is usually harvested to remove pollutants absorbed in plant tissues. However, the effect of plant harvesting during summer on the performance of
[...] Read more.
Plants can remove pollutants through direct absorption and by providing habitats for microbes to stimulate their activities. The aboveground plant biomass is usually harvested to remove pollutants absorbed in plant tissues. However, the effect of plant harvesting during summer on the performance of constructed wetlands and microbial abundance is unclear. In this study, three types of microcosms were set up, including: cleared group (both shoots and roots were harvested), harvested group (only shoots were harvested) and unharvested group. The concentrations of ammonia nitrogen and chemical oxygen demand in the effluent of the harvested group were the lowest. The nitrogen mass balance showed that summer harvesting improved nitrogen absorbance by plants, which was 1.24-times higher than that in the unharvested group. Interestingly, the other losses were taken up by the highest amounts in the cleared group, which were 1.66- and 3.72-times higher than in the unharvested and harvested group, respectively. Quantitative polymerase chain reaction revealed that harvesting of shoots during summer increased the microbial abundance. Additionally, Proteobacteria was the dominant phylum among all bacteria according to pyrosequencing analysis. These results indicate that harvesting of shoots during summer has positive effects on pollutant removal and microbial abundance. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)

Review

Jump to: Research

Open AccessReview Constructed Wetlands for Agricultural Wastewater Treatment in Northeastern North America: A Review
Water 2016, 8(5), 173; doi:10.3390/w8050173
Received: 1 March 2016 / Revised: 5 April 2016 / Accepted: 11 April 2016 / Published: 27 April 2016
Cited by 3 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
Constructed wetlands (CW) are a treatment option for agricultural wastewater. Their ability to adequately function in cold climates continues to be evaluated as they are biologically active systems that depend on microbial and plant activity. In order to assess their performance and to
[...] Read more.
Constructed wetlands (CW) are a treatment option for agricultural wastewater. Their ability to adequately function in cold climates continues to be evaluated as they are biologically active systems that depend on microbial and plant activity. In order to assess their performance and to highlight regional specific design considerations, a review of CWs in Eastern Canada and the Northeastern USA was conducted. Here, we synthesize performance data from 21 studies, in which 25 full-scale wetlands were assessed. Where possible, data were separated seasonally to evaluate the climatic effects on treatment performance. The wastewater parameters considered were five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), E. coli, fecal coliforms, total Kjeldahl nitrogen (TKN), ammonia/ammonium (NH3/NH4+-N), nitrate-nitrogen (NO3-N), and total phosphorus (TP). Average concentration reductions were: BOD5 81%, TSS 83%, TKN 75%, NH4+-N 76%, NO3-N 42%, and TP 64%. Average log reductions for E. coli and fecal coliforms were 1.63 and 1.93, respectively. Average first order areal rate constants (ka, m·y−1) were: BOD5 6.0 m·y−1, TSS 7.7 m·y−1, E. coli 7.0 m·y−1, fecal coliforms 9.7 m·y−1, TKN 3.1 m·y−1, NH4+-N 3.3 m·y−1, NO3-N 2.5 m·y−1, and TP 2.9 m·y−1. In general, CWs effectively treated a variety of agricultural wastewaters, regardless of season. Full article
(This article belongs to the Special Issue Constructed Wetlands Systems and Management)

Submitted Abstracts

Title: Applicability of Constructed Wetlands to Treat Source-Separated Domestic Grey Wastewater-A Decade of
Dutch Experiences
Author: Tiemen A. Nanninga 1,*,
Affiliation: 1 Lettinga Associates Foundation, P.O. Box 500, 6700 AM Wageningen, The Netherlands;
* Author to whom correspondence should be addressed; E-Mail: tiemen.nanninga@wur.nl; Tel.: +31-317-483-202.
Abstract
Introduction: Constructed wetlands (CWs) are increasingly being implemented as a decentralised wastewater
treatment technology in both Northern and Southern countries. Although CWs have been used to treat
wastewater since the 1950’s, most of the experiences documented focus on technical performances during the
first three years after construction. Thus while CWs are often promoted as being a suitable technology for
wastewater treatment, long-term non-technical experiences are poorly documented.
Aim: The aim of this paper is to learn from experiences with CWs that treat grey wastewater at neighbourhood
scale for a decade or more and to identify possible constraints for future implementation of CWs. Three case
study sites in the Netherlands (Drielanden in Groningen; Polderdrift in Arnhem; Lanxmeer in Culemborg) serve
to assess socio-technical factors related to the operation of CWs. In addition, the performance of CWs
functioning longer than eight years will be assessed by conducting a sampling programme at one site (Lanxmeer)
under challenging conditions (winter). The constraints identified will be analysed in order to allow for
translocation to Southern countries.
Methodology: The implementation process, costs, operation and maintenance (O&M) requirements and
structures, functioning, performance, perceptions and experiences were investigated using 34 semi-structured
interviews with users, operators, policy makers, constructors and consultants. Literature reviews were used to
gather background information about the cases, wastewater, CWs and results from previously performed
sampling programmes. 36 Influent and effluent composite samples were collected during the last week of
January and first week of February 2011 from three vertical sub-surface flow CWs in Lanxmeer and analysed for
BOD5, COD, TKN, NO3-, NO2-, NH4+, Ptotal, TSS, E.coli, dissolved O2, pH and Temperature.
Results: Results show that annual renewal and O&M costs (€230-€285/household) were a bit lower than the
annual costs of the conventional wastewater treatment system in Culemborg (€292.06-€398.18/household), that
maintenance requirements proved to be more work and more complex than initially anticipated and that all CWs
needed adjustments or major revisions during start-up. In all three cases there were people highly motivated to
ensure that the CWs were implemented and used. Very good removal efficiencies were found during the
sampling programme (BOD5: 97.7-99.9%, COD: 89.1-96.7%, Ntotal: 42.8-95.0%, NH4
+: 66.5-99.7%, Ptotal: 69.4-
97.5%, TSS: 19.4-96.7%, E.coli reduction of Log 2.5-5.2), which were similar or better compared to those of the
nearby conventional wastewater treatment plant. In general operators and users were positive about the CWs.
Conclusions: CWs have shown to be comparable in costs and efficiency to conventional technologies, yet the
start-up and operational and maintenance requirements proved to be more demanding than anticipated. Thus
despite often being promoted as robust, simple and ideal for rural areas, CWs have critical boundary conditions
that are actually quite complex and need to be addressed to ensure successful functioning.
Keywords: constructed wetlands, grey wastewater, decentralised, performance, operation and maintenance,
costs, implementation, users’ perceptions

Title: Economic Valuation of Constructed Wetlands with Treated Wastewater: A Review of Environmental Valuation Techniques and Ecosystemic Services
Author: Oscar Alfranca
Abstract: The objective of the paper is to revise the main literature on the use of environmental valuation techniques for the calculation of the environmental value of wetlands with treated wastewater. In the paper the efficiency of the different environmental valuation techniques to evaluate the main ecosystemic services related to wetlands will be discussed, both considering the relevance of the different economic and hydrological conditions. So finally, the quality of the different environmental valuation techniques is examined, and also the efficiency of these techniques to quantify the different environmental and economic characteristics of the constructed wetlands.

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