Science.gov

Sample records for a-01 constructed wetland

  1. Environmental assessment for the A-01 outfall constructed wetlands project at the Savannah River Site

    SciTech Connect

    1998-10-01

    The Department of Energy (DOE) prepared this environmental assessment (EA) to analyze the potential environmental impacts associated with the proposed A-01 outfall constructed wetlands project at the Savannah River site (SRS), located near aiken, South Carolina. The proposed action would include the construction and operation of an artificial wetland to treat effluent from the A-01 outfall located in A Area at SRS. The proposed action would reduce the outfall effluent concentrations in order to meet future outfall limits before these go into effect on October 1, 1999. This document was prepared in compliance with the National Environmental Policy Act (NEPA) of 1969, as amended; the requirements of the Council on Environmental Quality Regulations for Implementing NEPA (40 CFR Parts 1500--1508); and the DOE Regulations for Implementing NEPA (10 CFR Part 1021).

  2. WasteWater Treatment And Heavy Metals Removal In The A-01 Constructed Wetland 2003 Report

    SciTech Connect

    ANNA, KNOX

    2004-08-01

    The A-01 wetland treatment system (WTS) was designed to remove metals from the effluent at the A-01 NPDES outfall. The purpose of research conducted during 2003 was to evaluate (1) the ability of the A-01 wetland treatment system to remediate waste water, (2) retention of the removed contaminants in wetland sediment, and (3) the potential remobilization of these contaminants from the sediment into the water column. Surface water and sediment samples were collected and analyzed in this study.

  3. Constructed Wetlands

    EPA Pesticide Factsheets

    these systems can improve water quality, engineers and scientists construct systems that replicate the functions of natural wetlands. Constructed wetlands are treatment systems that use natural processes

  4. Baseline Hydrosoil Chemistry of the A-01 Wetland Treatment System, September 2001

    SciTech Connect

    Specht, W.L.

    2002-07-10

    The A-01 wetland treatment system was designed to remove metals from effluent from the A-01 NPDES outfall. Construction of the treatment system was completed in the summer of 2000 and all treatment cells were receiving A-01 effluent by July 2000. In September 2001, hydrosoil samples were collected from two of the treatment cells and analyzed for a suite of chemical parameters. The data indicate that copper and zinc are accumulating primarily in the surficial hydrosoils of the first treatment cells (A cells). Mercury was below the detection limit in most samples. However, the monthly data for mercury in water samples collected from the inflow and outflow of the treatment cells indicates that more mercury is removed in the A cells than in the B cells. The hydrosoils in the wetland treatment system have relatively low concentrations of organic carbon and a relatively low cation exchange capacity, due to the sandy nature of the hydrosoil and low organic content. Cation exchange capacity is expected to increase as organic matter produced by the wetland vegetation accretes in the wetland. Even though the wetland is removing metals from the A-01 effluent to concentrations that are below regulatory limits, as the treatment system matures, its ability to remove metals from the A-01 effluent is expected to increase. This report summarizes the hydrosoil chemistry data.

  5. ENGINEERING BULLETIN: CONSTRUCTED WETLANDS TREATMENT

    EPA Science Inventory

    Constructed wetlands have been demonstrated effective in removing organic, metal, and nutrient elements including nitrogen and phosphorus from municipal wastewaters, mine drainage, industrial effluents, and agricultural runoff. The technology is waste stream-specific, requiring...

  6. ENGINEERING BULLETIN: CONSTRUCTED WETLANDS TREATMENT

    EPA Science Inventory

    Constructed wetlands have been demonstrated effective in removing organic, metal, and nutrient elements including nitrogen and phosphorus from municipal wastewaters, mine drainage, industrial effluents, and agricultural runoff. The technology is waste stream-specific, requiring...

  7. Pesticide mitigation capacities of constructed wetlands

    Treesearch

    Matthew T. Moore; Charles M. Cooper; Sammie Smith; John H. Rodgers

    2000-01-01

    This research focused on using constructed wetlands along field perimeters to buffer receiving water against potential effects of pesticides associated with storm runoff. The current study incorporated wetland mesocosm sampling following simulated runoff events using chlorpyrifos, atrazine, and metolachlor. Through this data collection and simple model analysis,...

  8. Biogeochemical Characterization of Constructed Wetland Functions

    NASA Astrophysics Data System (ADS)

    Dalzell, B. J.; Parker, G. R.; Filley, T. R.

    2001-12-01

    Agricultural productions areas of the Midwestern United States are recognized as significant contributors of nonpoint source pollution and influence many aspects of water quality at both local and regional scales. In addition, ambitious land "improvement" programs stemming back to the mid-1800s have resulted in widespread loss of wetlands throughout the U.S., including heavy losses in agricultural production areas of the Mississippi River Basin. The combination of these two factors has been directly implicated as a contributing factor to high-profile environmental problems such as exacerbation of the zone of hypoxia in the Gulf of Mexico. Constructed wetlands are recognized for their potential to help mitigate the effects of agricultural nonpoint source pollution and previous loss of wetlands. The vast majority of previous studies of constructed wetlands have focused on the bulk movement of water quality constituents such as nitrogen, phosphorus, total carbon and sediment. While insightful, these studies do not address more detailed aspects of wetland function as it pertains to carbon flux and storage. In this study, we present results from biogeochemical analyses of influent and effluent of an experimental wetland constructed near row crop and animal production facilities in North-central Indiana. Cross flow utrafiltration and chemolytic techniques were used to collect and characterize organic components of wetland influent and effluent. Biomarker molecules were used to describe functions of the constructed wetland.

  9. A Constructed Wetland: From Monitoring To Action.

    ERIC Educational Resources Information Center

    Kowal, Dan

    1998-01-01

    Presents a water-quality monitoring project in a Denver school that has evolved into an experiment using a constructed wetland system to treat the acid-mine drainage from an abandoned gold mine. (PVD)

  10. A Constructed Wetland: From Monitoring To Action.

    ERIC Educational Resources Information Center

    Kowal, Dan

    1998-01-01

    Presents a water-quality monitoring project in a Denver school that has evolved into an experiment using a constructed wetland system to treat the acid-mine drainage from an abandoned gold mine. (PVD)

  11. Experiences with constructed wetland systems in Korea

    NASA Astrophysics Data System (ADS)

    Youngchul, Kim; Gilson, Hwang; Jin-Woo, Lee; Je-Chul, Park; Dong-Sup, Kim; Min-Gi, Kang; in-Soung, Chang

    2006-10-01

    In spite of the low temperature during the winter season and the high land environment, the wetland treatment system is gaining popularity in Korea because of its lower construction cost and simplicity in operation and maintenance. Many different types of wetland treatment systems have been built during the last 10 years, among which the free water surface wetland has been predominant. Most of the large-scale systems are government projects for improving the water quality of the streams flowing into the estuary dikes and reservoirs. The covering plants used in this system are different in different areas but cattails and reeds or their combinations are common. Constructed wetlands in Korea can be characterized by their shallow depths and short hydraulic residence times. There is no established flow pattern and configuration rules for constructing wetlands, but many efforts have been made with a view to improving their ecological function. Flow control is the most difficult problem in designing a riverbed or riparian wetland. There have been scores of flow rate control devices developed for wetlands, but none of them guarantee wetlands’ safety against flooding. In earlier wetland construction, the building materials were mainly soil. Recently, strong and durable building materials such as rocks, gravel beds, concrete and steel are used at vulnerable places to protect them from erosion. Our investigation indicated that the wetland system would be an appropriate technology because it is not only cheaper to construct, but also requires less maintenance work. However, we suffer from the reduced effectiveness in performance during the winter. We need to evaluate the partial treatment accomplished during 6 to 7 months per year.

  12. Groundwater Flow Through a Constructed Treatment Wetland

    DTIC Science & Technology

    2003-03-01

    should be constructed in an area where the contaminated water can be efficiently pumped into the wetland. Locating the wetland near the... water into the piezometer, and then back out again repeatedly. Pumping water in and out of the piezometer clears the screen of any clogging by...tests where the rate of receding water was so quick so as to allow gathering only a few head measurements, amounting to about half of all the pump

  13. Constructed wetlands as biofuel production systems

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Wu, Xu; Chang, Jie; Gu, Baojing; Min, Yong; Ge, Ying; Shi, Yan; Xue, Hui; Peng, Changhui; Wu, Jianguo

    2012-03-01

    Clean biofuel production is an effective way to mitigate global climate change and energy crisis. Progress has been made in reducing greenhouse-gas (GHG) emissions and nitrogen fertilizer consumption through biofuel production. Here we advocate an alternative approach that efficiently produces cellulosic biofuel and greatly reduces GHG emissions using waste nitrogen through wastewater treatment with constructed wetlands in China. Our combined experimental and literature data demonstrate that the net life-cycle energy output of constructed wetlands is higher than that of corn, soybean, switchgrass, low-input high-diversity grassland and algae systems. Energy output from existing constructed wetlands is ~237% of the input for biofuel production and can be enhanced through optimizing the nitrogen supply, hydrologic flow patterns and plant species selection. Assuming that all waste nitrogen in China could be used by constructed wetlands, biofuel production can account for 6.7% of national gasoline consumption. We also find that constructed wetlands have a greater GHG reduction than the existing biofuel production systems in a full life-cycle analysis. This alternative approach is worth pursuing because of its great potential for straightforward operation, its economic competitiveness and many ecological benefits.

  14. MANUAL - CONSTRUCTED WETLANDS TREATMENT OF MUNICIPAL WASTEWATERS

    EPA Science Inventory

    Constructed wetlands are man-made wastewater treatment systems. They usually have one or more cells less than 1 meter deep and are planted with aquatic greenery. Water outlet structures control the flow of wastewater through the system to keep detention times and water levels at ...

  15. MANUAL - CONSTRUCTED WETLANDS TREATMENT OF MUNICIPAL WASTEWATERS

    EPA Science Inventory

    Constructed wetlands are man-made wastewater treatment systems. They usually have one or more cells less than 1 meter deep and are planted with aquatic greenery. Water outlet structures control the flow of wastewater through the system to keep detention times and water levels at ...

  16. Removal of metals in constructed wetlands

    SciTech Connect

    Crites, R.W.; Watson, R.C.; Williams, C.R.

    1996-12-31

    Trace metals are difficult to remove from municipal wastewater by conventional wastewater treatment methods. Constructed wetlands have the potential to trap and remove metals from the water column. Long term removal is expected to occur by accumulation and burial in the plant detritus in a manner similar to the removal of phosphorus. Few data are available in the literature on removal of metals by constructed wetlands. A free water surface constructed wetland at Sacramento Regional Wastewater Treatment Plant treating secondary municipal effluent has been operating since the spring of 1994. Removal data for 13 metals are presented for the period from August 1994 to May 1995. About 3,785 m{sup 3}/d (1 mgd) of pure oxygen activated sludge effluent, disinfected using UV light, is further treated through a 8 ha (20 acre) constructed wetlands Ten separate, parallel treatment cells are available to demonstrate the effects of detention time, vegetation management, and application frequency on the removal of metals, organics and ammonia. Detention time can be varied from 3 to 13 days by varying the flow and the water depth. The vegetation, primarily bulrush with some cattails, will be managed by different techniques to minimize mosquito production. Application frequency varies from continuous flow to batch flow (1 to 2 days of loading with 1 day of discharge).

  17. Are constructed treatment wetlands sustainable sanitation solutions?

    PubMed

    Langergraber, Guenter

    2013-01-01

    The main objective of sanitation systems is to protect and promote human health by providing a clean environment and breaking the cycle of disease. In order to be sustainable, a sanitation system has to be not only economically viable, socially acceptable and technically and institutionally appropriate, but it should also protect the environment and the natural resources. 'Resources-oriented sanitation' describes the approach in which human excreta and water from households are recognized as resource made available for reuse. Nowadays, 'resources-oriented sanitation' is understood in the same way as 'ecological sanitation'. For resources-oriented sanitation systems to be truly sustainable they have to comply with the definition of sustainable sanitation as given by the Sustainable Sanitation Alliance (SuSanA, www.susana.org). Constructed treatment wetlands meet the basic criteria of sustainable sanitation systems by preventing diseases, protecting the environment, and being an affordable, acceptable, and simple technology. Additionally, constructed treatment wetlands produce treated wastewater of high quality, which is fostering reuse, which in turn makes them applicable in resources-oriented sanitation systems. The paper discusses the features that make constructed treatment wetlands a suitable solution in sustainable resources-oriented sanitation systems, the importance of system thinking for sustainability, as well as key factors for sustainable implementation of constructed wetland systems.

  18. Forested wetlands constructed for mitigation of destroyed natural wetlands

    USGS Publications Warehouse

    Perry, M.C.; Pugh, S.B.; Deller, A.S.

    1995-01-01

    Forested wetlands constructed for mitigation were evaluated at six sites in Maryland to determine the success of these areas for providing suitable wildlife habitat. Natural forested wetlands were used as reference sites. Initial mortality of planted woody shrubs and trees was high (avg. 55%) and mostly attributed to excessive moisture. The number of woody seedlings from natural regeneration was inversely proportional to the amount of grass cover on the site, which was planted for erosion control. The number of volunteer woody seedlings was also inversely proportional to the distance from adjacent natural forests. Preliminary data indicate that cost does not support use of transplants and that enhancement of soil with organic supplements, followed by widespread and heavy seeding of woody plants would be more efficient and effective. Wildlife use of areas measured by avian surveys and trapping of mammals, reptiles, and amphibians showed that in general wildlife species were more representative of open grassland areas than forested habitats. Natural succession of the sites probably will take at least 20-30 years before typical values and functions of forested wetlands are obtained.

  19. Removal processes for arsenic in constructed wetlands.

    PubMed

    Lizama A, Katherine; Fletcher, Tim D; Sun, Guangzhi

    2011-08-01

    Arsenic pollution in aquatic environments is a worldwide concern due to its toxicity and chronic effects on human health. This concern has generated increasing interest in the use of different treatment technologies to remove arsenic from contaminated water. Constructed wetlands are a cost-effective natural system successfully used for removing various pollutants, and they have shown capability for removing arsenic. This paper reviews current understanding of the removal processes for arsenic, discusses implications for treatment wetlands, and identifies critical knowledge gaps and areas worthy of future research. The reactivity of arsenic means that different arsenic species may be found in wetlands, influenced by vegetation, supporting medium and microorganisms. Despite the fact that sorption, precipitation and coprecipitation are the principal processes responsible for the removal of arsenic, bacteria can mediate these processes and can play a significant role under favourable environmental conditions. The most important factors affecting the speciation of arsenic are pH, alkalinity, temperature, dissolved oxygen, the presence of other chemical species--iron, sulphur, phosphate--,a source of carbon, and the wetland substrate. Studies of the microbial communities and the speciation of arsenic in the solid phase using advanced techniques could provide further insights on the removal of arsenic. Limited data and understanding of the interaction of the different processes involved in the removal of arsenic explain the rudimentary guidelines available for the design of wetlands systems.

  20. Estimating evapotranspiration in natural and constructed wetlands

    USGS Publications Warehouse

    Lott, R. Brandon; Hunt, Randall J.

    2001-01-01

    Difficulties in accurately calculating evapotranspiration (ET) in wetlands can lead to inaccurate water balances—information important for many compensatory mitigation projects. Simple meteorological methods or off-site ET data often are used to estimate ET, but these approaches do not include potentially important site-specific factors such as plant community, root-zone water levels, and soil properties. The objective of this study was to compare a commonly used meterological estimate of potential evapotranspiration (PET) with direct measurements of ET (lysimeters and water-table fluctuations) and small-scale root-zone geochemistry in a natural and constructed wetland system. Unlike what has been commonly noted, the results of the study demonstrated that the commonly used Penman combination method of estimating PET underestimated the ET that was measured directly in the natural wetland over most of the growing season. This result is likely due to surface heterogeneity and related roughness efffects not included in the simple PET estimate. The meterological method more closely approximated season-long measured ET rates in the constructed wetland but may overestimate the ET rate late in the growing season. ET rates also were temporally variable in wetlands over a range of time scales because they can be influenced by the relation of the water table to the root zone and the timing of plant senescence. Small-scale geochemical sampling of the shallow root zone was able to provide an independent evaluation of ET rates, supporting the identification of higher ET rates in the natural wetlands and differences in temporal ET rates due to the timing of senescence. These discrepancies illustrate potential problems with extrapolating off-site estimates of ET or single measurements of ET from a site over space or time.

  1. HANDBOOK FOR CONSTRUCTED WETLANDS RECEIVING ACID MINE DRAINAGE

    EPA Science Inventory

    In the summer of 1987, a pilot constructed wetland was built at the Big Five Tunnel in Idaho Springs, Colorado. This report details the theory, design and construction of wetlands receiving acid mine drainages, based on the second and third year of operation of this wetland, whic...

  2. Elemental composition of native wetland plants in constructed mesocosm treatment wetlands.

    PubMed

    Collins, Beverly S; Sharitz, Rebecca R; Coughlin, Daniel P

    2005-05-01

    Plants that accumulate a small percentage of metals in constructed treatment wetlands can contribute to remediation of acidic, metal contaminated runoff waters from coal mines or processing areas. We examined root and shoot concentrations of elements in four perennial wetland species over two seasons in mesocosm wetland systems designed to remediate water from a coal pile runoff basin. Deep wetlands in each system contained Myriophyllum aquaticum and Nymphaea odorata; shallow wetlands contained Juncus effusus and Pontederia cordata. Shoot elemental concentrations differed between plants of deep and shallow wetlands, with higher Zn, Al, and Fe concentrations in plants in shallow wetlands and higher Na, Mn, and P concentrations in plants in deep wetlands. Root and shoot concentrations of most elements differed between species in each wetland type. Over two seasons, these four common wetland plants did help remediate acidic, metal-contaminated runoff from a coal storage pile.

  3. Clay particle retention in small constructed wetlands.

    PubMed

    Braskerud, B C

    2003-09-01

    Constructed wetlands (CWs) can be used to mitigate non-point source pollution from arable fields. Previous investigations have shown that the relative soil particle retention in small CWs increases when hydraulic load increases. This paper investigates why this phenomenon occurs, even though common retention models predict the opposite, by studying clay and silt particle retention in two Norwegian CWs. Retention was measured with water flow proportional sampling systems in the inlet and outlet of the wetlands, and the texture of the suspended solids was analyzed. The surface area of the CWs was small compared to the watershed area (approximately 0.07%), giving high average hydraulic loads (1.1 and 2.0 md(-1)). One of the watersheds included only old arable land, whereas the other included areas with disturbed topsoil after artificial land leveling. Clay particle retention was 57% for the CW in the first watershed, and 22% for the CW in the disturbed watershed. The different behavior of the wetlands could be due to differences in aggregate size and stability of the particles entering the wetlands. Results showed that increased hydraulic loads did affect CW retention negatively. However, as runoff increased, soil particles/aggregates with higher sedimentation velocities entered the CWs (e.g., the clay particles behaved as silt particles). Hence, clay particle settling velocity is not constant as assumed in many prediction models. The net result was increased retention.

  4. Environmental footprint of constructed wetlands treating wastewater.

    PubMed

    Gkika, Dimitra; Gikas, Georgios D; Tsihrintzis, Vassilios A

    2015-01-01

    The aim of the study is to determine environmentally friendlier construction materials for constructed wetland facilities treating wastewater. This is done by computing the environmental footprint of the facility based on the methodology of life cycle assessment (LCA). This methodology reveals the dominant aggravating processes during the construction of a constructed wetland (CW) and can help to create alternative environmentally friendlier solutions. This methodology was applied for the determination of the overall environmental profile of a hybrid CW facility. The LCA was applied first to the facility as originally designed, where reinforced concrete was used in some components. Then, alternative construction materials to reinforced concrete were used, such as earth covered with high density polyethylene (HDPE) or clay, and LCA was applied again. Earth structures were found to have reduced environmental impact compared to concrete ones, and clay was found environmentally friendlier compared to HDPE. Furthermore, estimation of the construction costs of the three scenarios indicate that the last scenario is also the least expensive.

  5. Construction and operation costs of constructed wetlands treating wastewater.

    PubMed

    Gkika, Dimitra; Gikas, Georgios D; Tsihrintzis, Vassilios A

    2014-01-01

    Design data from nine constructed wetlands (CW) facilities of various capacities (population equivalent (PE)) are used to estimate construction and operation costs, and then to derive empirical equations relating the required facility land area and the construction cost to PE. In addition, comparisons between the costs of CW facilities based on various alternative construction materials, i.e., reinforced concrete and earth structures (covered with either high density polyethylene or clay), are presented in relation to the required area. The results show that earth structures are economically advantageous. The derived equations can be used for providing a preliminary cost estimate of CW facilities for domestic wastewater treatment.

  6. Albuquerque's constructed wetland pilot project for wastewater polishing

    Treesearch

    Michael D. Marcus; Shannon M. House; Nathan A. Bowles; Robert T. Sekiya; J. Steven Glass

    1999-01-01

    The City of Albuquerque has funded the Constructed Wetland Pilot Project (CWPP) since 1995 at the City's Southside Water Reclamation Plant (SWRP). Results from CWPP and other wetland treatment projects indicate that appropriately designed surface-flow wetlands could increase the cost-efficiencies of wastewater treatment, as well as help the City meet present and...

  7. Metals Retention in Constructed Wetland Sediments

    SciTech Connect

    KNOX, ANNA

    2004-10-27

    The A-01 wetland treatment system (WTS) was designed to remove metals from the effluent at the A-01 NPDES outfall at the Savannah River Site, Aiken, SC. Sequential extraction data was used to evaluate remobilization and retention of Cu, Pb, Zn, Mn, and Fe in the wetland sediment. Remobilization of metals was determined by the Potentially Mobile Fraction (PMF) and metal retention by the Recalcitrant Factor (RF). The PMF, which includes water soluble, exchangeable, and oxides fractions, is the contaminant fraction that has the potential to enter into the mobile aqueous phase under changeable environmental conditions. PMF values were low for Cu, Zn and Pb (about 20 percent) and high for Fe and Mn (about 60 to 70 percent). The RF, which includes crystalline oxides, sulfides or silicates and aluminosilicates, is the ratio of strongly bound fractions to the total concentration of elements in sediment. RF values were about 80 percent for Cu, Zn and Pb, indicating high retention in the sediment and 30 percent to above 40 percent for Fe and Mn indication low retention.

  8. [Problems and countermeasures in the application of constructed wetlands].

    PubMed

    Huang, Jin-Lou; Chen, Qin; Xu, Lian-Huang

    2013-01-01

    Constructed wetlands as a wastewater eco-treatment technology are developed in recent decades. It combines sewage treatment with the eco-environment in an efficient way. It treats the sewage effectively, and meanwhile beautifies the environment, creates ecological landscape, and brings benefits to the environment and economics. The unique advantages of constructed wetlands have attracted intensive attention since developed. Constructed wetlands are widely used in treatment of domestic sewage, industrial wastewater, and wastewater from mining and petroleum production. However, many problems are found in the practical application of constructed wetland, e. g. they are vulnerable to changes in climatic conditions and temperature, their substrates are easily saturated and plugged, they are readily affected by plant species, they often occupy large areas, and there are other problems including irrational management, non-standard design, and a single function of ecological service. These problems to a certain extent influence the efficiency of constructed wetlands in wastewater treatment, shorten the life of the artificial wetland, and hinder the application of artificial wetland. The review presents correlation analysis and countermeasures for these problems, in order to improve the efficiency of constructed wetland in wastewater treatment, and provide reference for the application and promotion of artificial wetland.

  9. Application of constructed wetlands for wastewater treatment in Nepal.

    PubMed

    Shrestha, R R; Haberl, R; Laber, J; Manandhar, R; Mader, J

    2001-01-01

    Surface water pollution is one of the serious environmental problems in urban centers in Nepal due to the discharge of untreated wastewater into the river-system, turning them into open sewers. Wastewater treatment plants are almost non-existent in the country except for a few in the Kathmandu Valley and even these are not functioning well. Successful implementation of a few constructed wetland systems within the past three years has attracted attention to this promising technology. A two-staged subsurface flow constructed wetland for hospital wastewater treatment and constructed wetlands for treatment of greywater and septage is now becoming a demonstration site of constructed wetland systems in Nepal. Beside these systems, five constructed wetlands have already been designed and some are under construction for the treatment of leachate and septage in Pokhara municipality, wastewater in Kathmandu University, two hospitals and a school. This paper discusses the present condition and treatment performance of constructed wetlands that are now in operation. Furthermore, the concept of the treatment wetlands under construction is also described here. With the present experience, several recommendations are pointed out for the promotion of this technology in the developing countries.

  10. Nitrogen compounds in drain sewage after constructed wetlands.

    PubMed

    Paweska, K; Malczewska, B

    2009-01-01

    Constructed wetlands, commonly known as ground filters, are well suited mostly for wastewater treatment in areas with no central sewage system. The basic difficulty with exploitation of constructed wetlands is connected with irregular hydraulic overload of its surface. However, irregular wastewater inflow can be reduced by cyclical irrigation which increases efficiency. The unquestionable advantage of the constructed wetlands is inexpensive construction and exploitation as well as low energy consumption. The constructed wetlands also fit very well in surrounding area. The investigation concerned the analysis of two constructed wetlands which are composed of mechanical separation (septic tank) and a filter bed with subsurface flow. The research has been undertaken in a period from July to December 2008, with regard to concentration distribution of nitrogen compounds in municipal sewage after constructed wetlands. The preliminary investigation on constructed wetland which has been exploited for 10 years showed variable removal efficiency of nitrogen compounds. The continuation of the research can indicate the efficiency of wastewater treatment in summer and winter season.

  11. CONSTRUCTED WETLAND TREATMENT SYSTEMS FOR WATER QUALITY IMPROVEMENT

    SciTech Connect

    Nelson, E.

    2010-07-19

    The Savannah River National Laboratory implemented a constructed wetland treatment system (CWTS) in 2000 to treat industrial discharge and stormwater from the Laboratory area. The industrial discharge volume is 3,030 m{sup 3} per day with elevated toxicity and metals (copper, zinc and mercury). The CWTS was identified as the best treatment option based on performance, capital and continuing cost, and schedule. A key factor for this natural system approach was the long-term binding capacity of heavy metals (especially copper, lead, and zinc) in the organic matter and sediments. The design required that the wetland treat the average daily discharge volume and be able to handle 83,280 m{sup 3} of stormwater runoff in a 24 hour period. The design allowed all water flow within the system to be driven entirely by gravity. The CWTS for A-01 outfall is composed of eight one-acre wetland cells connected in pairs and planted with giant bulrush to provide continuous organic matter input to the system. The retention basin was designed to hold stormwater flow and to allow controlled discharge to the wetland. The system became operational in October of 2000 and is the first wetland treatment system permitted by South Carolina DHEC for removal of metals. Because of the exceptional performance of the A-01 CWTS, the same strategy was used to improve water quality of the H-02 outfall that receives discharge and stormwater from the Tritium Area of SRS. The primary contaminants in this outfall were also copper and zinc. The design for this second system required that the wetland treat the average discharge volume of 415 m{sup 3} per day, and be able to handle 9,690 m{sup 3} of stormwater runoff in a 24 hour period. This allowed the building of a system much smaller than the A-01 CWTS. The system became operational in July 2007. Metal removal has been excellent since water flow through the treatment systems began, and performance improved with the maturation of the vegetation during

  12. Lead and zinc removal by laboratory-scale constructed wetlands.

    PubMed

    Song, Y; Fitch, M; Burken, J; Nass, L; Chilukiri, S; Gale, N; Ross, C

    2001-01-01

    Constructed wetlands have the potential to trap and remove metals in mine wastewater. To determine the effectiveness of constructed wetlands for treating selected heavy metals in neutral mine effluent typical of lead mines, eight laboratory-scale constructed wetlands were set up to treat a synthetic, slightly alkaline, mine water containing 34.2 mg/L sulfate (SO4(2-)), 50 micrograms/L lead (Pb), and 300 micrograms/L zinc (Zn). After 45 days, one of the wetlands was switched to treat a synthetic smelter effluent with a much greater load of SO4(2-), sodium (Na+), and Pb. Temperature, hydraulic loading, and substrate composition typically did not affect treatment efficiency. The pH of the effluent was reduced from 8.0 to 8.5 to near neutral. The average removal in the eight wetlands was 90% for Pb and 72% for Zn. In wetlands operating on synthetic mine water, SO4(2-) was completely removed, likely by conversion to sulfide by sulfate-reducing bacteria. In the wetland operating on synthetic smelter effluent, only approximately 25% of 6 g/L influent sulfate was removed, and a breakthrough period of 4 days for Na+ was observed. Whole effluent toxicity assays on undiluted wetland effluent from wetlands treating mine and smelter water had 100% survival of fathead minnows and Daphnia magnia. Survival of Ceriodaphnia dubia was zero in undiluted effluent, but 75 to 100% survival was observed when the effluent was diluted to one-half strength.

  13. Review of Constructed Subsurface Flow vs. Surface Flow Wetlands

    SciTech Connect

    HALVERSON, NANCY

    2004-09-01

    The purpose of this document is to use existing documentation to review the effectiveness of subsurface flow and surface flow constructed wetlands in treating wastewater and to demonstrate the viability of treating effluent from Savannah River Site outfalls H-02 and H-04 with a subsurface flow constructed wetland to lower copper, lead and zinc concentrations to within National Pollutant Discharge Elimination System (NPDES) Permit limits. Constructed treatment wetlands are engineered systems that have been designed and constructed to use the natural functions of wetlands for wastewater treatment. Constructed wetlands have significantly lower total lifetime costs and often lower capital costs than conventional treatment systems. The two main types of constructed wetlands are surface flow and subsurface flow. In surface flow constructed wetlands, water flows above ground. Subsurface flow constructed wetlands are designed to keep the water level below the top of the rock or gravel media, thus minimizing human and ecological exposure. Subsurface flow wetlands demonstrate higher rates of contaminant removal per unit of land than surface flow (free water surface) wetlands, therefore subsurface flow wetlands can be smaller while achieving the same level of contaminant removal. Wetlands remove metals using a variety of processes including filtration of solids, sorption onto organic matter, oxidation and hydrolysis, formation of carbonates, formation of insoluble sulfides, binding to iron and manganese oxides, reduction to immobile forms by bacterial activity, and uptake by plants and bacteria. Metal removal rates in both subsurface flow and surface flow wetlands can be high, but can vary greatly depending upon the influent concentrations and the mass loading rate. Removal rates of greater than 90 per cent for copper, lead and zinc have been demonstrated in operating surface flow and subsurface flow wetlands. The constituents that exceed NPDES limits at outfalls H-02 a nd H

  14. Technical and Regulatory Guidance Document for Constructed Treatment Wetlands

    DTIC Science & Technology

    2003-12-01

    Wetlands Research Program Technical Report WRP-DE-4. Brix , H., 1993, “Wastewater Treatment in Constructed Wetlands: System Design, Removal...Opelousas, La. Constituents of Concern Influent BOD, 500– 3000 mg/L Regulatory Contact Name Robert Crawford, Louisiana DEQ Plant Hardiness Deep South

  15. Assessing hydrogeochemical heterogeneity in natural and constructed wetlands

    USGS Publications Warehouse

    Hunt, R.J.; Krabbenhoft, D.P.; Anderson, M.P.

    1997-01-01

    While 'water quality function' is cited as an important wetland function to design for and preserve, we demonstrate that the scale at which hydrochemical samples are collected can significantly influence interpretations of biogeochemical processes in wetlands. Subsurface, chemical profiles for both nutrients and major ions were determined at a site in southwestern Wisconsin that contained areas of both natural and constructed wetlands. Sampling was conducted on three different scales: (1) a large scale (3 m between sampling points), (2) an intermediate scale (0.15 m between sampling points), and (3) a small scale (1.5 cm between sampling points). In most cases, significant vertical heterogeneity was observed at the 0.15 m scale, which was much larger than previously reported for freshwater wetlands and not detected by sampling water table wells screened over the same interval. However, profiles of ammonia and total phosphorus showed tenfold changes in the upper 0.2 meters of the saturated zone when sampled at the small (1.5 cm) scale, that was not depicted by sampling at the intermediate scale. At the intermediate scale of observation, one constructed wetland site differed geochemically from the natural wetlands and the other constructed wetland site due to application of off-site salvaged marsh surface and downward infiltration of rain. While important differences in dissolved inorganic phosphorus and dissolved inorganic carbon concentrations existed between the constructed wetland and the natural wetlands, we also observed substantial differences between the natural wetland sites for these constituents. A median-polishing analysis of our data showed that temporal variations in constituent concentrations within profiles, although extensively recognized in the literature, were not as important as spatial variability.

  16. Use of Constructed Wetlands for Polishing Recharge Wastewater

    NASA Astrophysics Data System (ADS)

    Cardwell, W.

    2009-12-01

    The use of constructed wetlands for waste water treatment is becoming increasingly popular as more focus is being shifted to natural means of waste treatment. These wetlands employ processes that occur naturally and effectively remove pollutants and can greatly minimize costs when compared to full scale treatment plants. Currently, wetland design is based on basic “rules-of-thumb,” meaning engineers have a general understanding but not necessarily a thorough knowledge of the intricate physical, biological, and chemical processes involved in these systems. Furthermore, there is very little consideration given to use the wetland as a recharge pond to allow the treated water to percolate and recharge the local groundwater aquifers. The City of Foley, located in Alabama, and the Utilities Board of the City of Foley partnered with Wolf Bay Watershed Watch to evaluate alternative wastewater effluent disposal schemes. Rather than discharging the treated water into a local stream, a pilot program has been developed to allow water from the treatment process to flow into a constructed wetlands area where, after natural treatment, the treated water will then be allowed to percolate into a local unconfined aquifer. The goal of this study is to evaluate how constructed wetlands can be used for “polishing” effluent as well as how this treated water might be reused. Research has shown that constructed wetlands, with proper design and construction elements, are effective in the treatment of BOD, TSS, nitrogen, phosphorous, pathogens, metals, sulfates, organics, and other substances commonly found in wastewater. Mesocosms will be used to model the wetland, at a much smaller scale, in order to test and collect data about the wetland treatment capabilities. Specific objectives include: 1. Determine optimum flow rates for surface flow wetlands where water treatment is optimized. 2. Evaluate the capabilities of constructed wetlands to remove/reduce common over the counter

  17. The ecological value of constructed wetlands for treating urban runoff.

    PubMed

    Pankratz, S; Young, T; Cuevas-Arellano-, H; Kumar, R; Ambrose, R F; Suffet, I H

    2007-01-01

    The Sweetwater Authority's urban runoff diversion system (URDS) comprises constructed wetlands on a hillside between the town of Spring Valley and the Sweetwater Reservoir, California, USA. The URDS were designed to divert dry-weather and first-flush urban runoff flows from the Sweetwater reservoir. However, these constructed wetlands have developed into ecologically valuable habitat. This paper evaluates the following ecological questions related to the URDS: (1) the natural development of the species present and their growth pattern; (2) the biodiversity and pollutant stress on the plants and invertebrates; and (3) the question of habitat provided for endangered species. The URDS wetlands are comprised primarily of rush (Scirpus spp.) and cattails (Typha spp.). This vegetative cover ranged from 39-78% of the area of the individual wetland ponds. Current analyses of plant tissues and wetland sediment indicates the importance of sediment sorption for metals and plant uptake of nutrients. Analyses of URDS water following runoff events show the URDS wetlands do reduce the amount of nutrients and metals in the water column. Invertebrate surveys of the wetland ponds revealed lower habitat quality and environmental stress compared to unpolluted natural habitat. The value of the wetlands as wildlife habitat is constrained by low plant biodiversity and pollution stress from the runoff. Since the primary Sweetwater Authority goal is to maintain good water quality for drinking, any secondary utilization of URDS habitat by species (endangered or otherwise) is deemed an added benefit.

  18. Enzyme and root activities in surface-flow constructed wetlands.

    PubMed

    Kong, Ling; Wang, Yu-Bin; Zhao, Li-Na; Chen, Zhang-He

    2009-07-01

    Sixteen small-scale wetlands planted with four plant species were constructed for domestic wastewater purification. The objective of this study was to determine the correlations between contaminant removal and soil enzyme activity, root activity, and growth in the constructed wetlands. The results indicated that correlations between contaminant removal efficiency and enzyme activity varied depending on the contaminants. The removal efficiency of NH4+ was significantly correlated with both urease and protease activity in all wetlands, and the removal of total phosphorus and soluble reactive phosphorus was significantly correlated with phosphatase activity in most wetlands, while the removal of total nitrogen, NO3(-) , and chemical oxygen demand (COD) was significantly correlated with enzyme activity only in a few instances. Correlations between soil enzyme activity and root activity varied among species. Activities of all enzymes were significantly correlated with root activity in Vetiveria zizanioides and Phragmites australis wetlands, but not in Hymenocallis littoralis wetlands. Significant correlations between enzyme activity and root biomass and between enzyme activity and root growth were found mainly in Cyperus flabelliformis wetlands. Root activity was significantly correlated with removal efficiencies of all contaminants except NO3(-) and COD in V. zizanioides wetlands. Enzyme activities and root activity showed single-peak seasonal patterns. Activities of phosphatase, urease, and cellulase were significantly higher in the top layer of the substrate than in the deeper layers, and there were generally no significant differences between the deeper layers (deeper than 15 cm).

  19. Redox properties of a constructed wetland: theoretical and practical aspects.

    PubMed

    Síma, Jan; Diáková, Katerina; Pavelcová, Lenka; Havelka, Michal

    2009-03-01

    Constructed wetlands represent a progressive approach to the wastewater treatment. A fundamental prerequisite of the efficient water quality improvement is the presence of redox potential gradients (connected with the aeration of the system) inside the vegetation bed. Redox properties of a constructed wetland were tested in three longitudinal transects crossing the vegetation bed from the inflow zone to the outflow using diverse indicators (e.g., Fe(III)/Fe(II), SO(2-)(4)/S(2-)). Approximately 10-25% of iron was reoxidized in samples taken 10 m from the inflow zone in 2006. Redox processes of iron in artificial (constructed wetland) and natural (peat bog) ecosystems were compared. The peat bog was characterized with higher percentages of Fe(II) (usually ca. 90-100%). Thus, the aeration of the peat land was lower in comparison with the constructed wetland. The constructed wetland efficiently reduced sulfates (average concentrations of 44.7 and 11.2 mg/l at the inflow and the outflow, resp., in 2007). Organics, expressed as COD(Cr) and BOD(5), and NH+(4) were removed with efficiencies of 86.4, 92.2, and 60.4%, respectively. However, total phosphorus (redox processes play a negligible role in this case) was removed only with 39.6% efficiency. Redox properties of the wetland did not significantly depend on the heterogeneity of the treated wastewater flow.

  20. Simulation of arsenic retention in constructed wetlands.

    PubMed

    Valles-Aragón, M C; Alarcón-Herrera, M T; Llorens, E; Obradors-Prats, J; Leyva, A

    2017-01-01

    The software RCB-arsenic was developed previously to simulate the metalloid behavior in a constructed wetland (CW). The model simulates water flow and reactive transport by contemplating the major processes of arsenic (As) retention inside of CW. The objective of this study was to validate the RCB-arsenic model by simulating the behavior of horizontal flow CW for As removal from water. The model validation was made using data from a 122-day experiment. Two CWs prototypes were used: one planted with Eleocharis macrostachya (CW_planted) and another one unplanted (CW_unplanted) as a control. The prototypes were fed with synthetic water prepared using well water and sodium arsenite (NaAsO2). In the RCB-arsenic model, a CW prototype was represented using a 2D mesh sized in accordance with the experiment. For simulation of As retention in CW, data addition was established in two stages that considered the mechanisms in the system: (1) aqueous complexation, precipitation/dissolution, and adsorption on granular media and (2) retention by plants: uptake (absorption) and rhizofiltration (adsorption). Simulation of As outlet (μg/L) in stage_1 was compared with CW_unplanted; the experimental mean was 40.79 ± 7.76 and the simulated 39.96 ± 6.32. As concentration (μg/L) in stage_2 was compared with CW_planted, the experimental mean was 9.34 ± 4.80 and the simulated 5.14 ± 0.72. The mass-balance simulation and experiment at 122 days of operation had a similar As retention rate (94 and 91%). The calibrated model RCB-arsenic adequately simulated the As retention in a CW; therefore, it constitutes a powerful tool of design.

  1. Paracetamol removal in subsurface flow constructed wetlands

    NASA Astrophysics Data System (ADS)

    Ranieri, Ezio; Verlicchi, Paola; Young, Thomas M.

    2011-07-01

    SummaryIn this study two pilot scale Horizontal Subsurface Flow Constructed Wetlands (HSFCWs) near Lecce, Italy, planted with different macrophytes ( Phragmites australis and Typha latifolia) and an unplanted control were assessed for their effectiveness in removing paracetamol. Residence time distributions (RTDs) for the two beds indicated that the Typha bed was characterized by a void volume fraction (porosity) of 0.16 and exhibited more ideal plug flow behavior (Pe = 29.7) than the Phragmites bed (Pe = 26.7), which had similar porosity. The measured hydraulic residence times in the planted beds were 35.8 and 36.7 h when the flow was equal to 1 m 3/d. The Phragmites bed exhibited a range of paracetamol removals from 51.7% for a Hydraulic Loading Rate (HLR) of 240 mm/d to 87% with 120 mm/d HLR and 99.9% with 30 mm/d. The Typha bed showed a similar behavior with percentages of removal slightly lower, ranging from 46.7% (HLR of 240 mm/d) to >99.9% (hydraulic loading rate of 30 mm/d). At the same HLR values the unplanted bed removed between 51.3% and 97.6% of the paracetamol. In all three treatments the paracetamol removal was higher with flow of 1 m 3/d and an area of approx. 7.5 m 2 (half bed) than in the case of flow equal to 0.5 m 3/d with a surface treatment of approx. 3.75 m 2. A first order model for paracetamol removal was evaluated and half lives of 5.16 to 10.2 h were obtained.

  2. Denitrification in constructed wetlands used for treatment of swine wastewater.

    PubMed

    Hunt, Patrick G; Matheny, Terry A; Szögi, Ariel A

    2003-01-01

    Constructed wetland treatment of swine wastewater probably involves substantial denitrification. Our objective was to assess denitrification and denitrification enzyme activity (DEA) in such wetlands in relation to plant communities, N loading, carbon or nitrogen limitations, and water depth. Two wetland cells each 3.6 m wide and 33.5 m long were connected in series. One set of cells was planted with rushes and bulrushes, including soft rush (Juncus effusus L.), softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal, American bulrush [Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller], and woolgrass bulrush [Scirpus cyperinus (L.) Kunth]. Another set was planted with bur-reeds and cattails, including American bur-reed (Sparganium americanum Nutt.), broadleaf cattail (Typha latifolia L.), and narrowleaf cattail (Typha angustifolia L.). The sets will be referred to herein as bulrush and cattail wetlands, respectively. Denitrification and DEA were measured via the acetylene inhibition method in intact soil cores and disturbed soil samples that were taken during four years (1994-1997). Although DEA in the disturbed samples was greater than denitrification in the core samples, the measurements were highly correlated (r2 > or = 0.82). The DEA was greater in the bulrush wetlands than the cattail wetlands, 0.516 and 0.210 mg N kg(-1) soil h(-1), respectively; and it increased with the cumulative applied N. The DEA mean was equivalent to 9.55 kg N ha(-1) d(-1) in the bulrush wetlands. We hypothesized and confirmed that DEA was generally limited by nitrate rather than carbon. Moreover, we determined that one of the most influential factors in DEA was wetland water depth. In bulrush wetlands, the slope and r2 values of the control treatment were -0.013 mg N kg(-1) soil h(-1) mm(-1) depth and r2 = 0.89, respectively. Results of this investigation indicate that DEA can be very significant in constructed wetlands used to treat swine wastewater.

  3. Microbial biomass, activity and community composition in constructed wetlands.

    PubMed

    Truu, Marika; Juhanson, Jaanis; Truu, Jaak

    2009-06-15

    The aim of the current article is to give an overview about microbial communities and their functioning but also about factors affecting microbial activity in the three most common types (surface flow and two types of sub-surface flow) of constructed wetlands. The paper reviews the community composition and structural diversity of the microbial biomass, analyzing different aspects of microbial activity with respect to wastewater properties, specific wetland type, and environmental parameters. A brief introduction about the application of different novel molecular techniques for the assessment of microbial communities in constructed wetlands is also given. Microbially mediated processes in constructed wetlands are mainly dependent on hydraulic conditions, wastewater properties, including substrate and nutrient quality and availability, filter material or soil type, plants, and different environmental factors. Microbial biomass is within similar ranges in both horizontal and vertical subsurface flow and surface flow constructed wetlands. Stratification of the biomass but also a stratified structural pattern of the bacterial community can be seen in subsurface flow systems. Microbial biomass C/N ratio is higher in horizontal flow systems compared to vertical flow systems, indicating the structural differences in microbial communities between those two constructed wetland types. The total activity of the microbial community is in the same range, but heterotrophic growth is higher in the subsurface (vertical flow) system compared to the surface flow systems. Available species-specific data about microbial communities in different types of wetlands is scarce and therefore it is impossible make any general conclusions about the dynamics of microbial community structure in wetlands, its relationship to removal processes and operational parameters.

  4. Greenhouse gas emissions from constructed wetlands treating dairy wastewater

    NASA Astrophysics Data System (ADS)

    Glass, Vimy M.

    In Nova Scotia, constructed wetland systems are widely considered as effective treatment systems for agricultural wastewater. Although research has examined the water quality treatment attributes, there has been limited focus on the air quality effects of these systems. Six operational pilot-scale constructed wetlands were built with flow-through chambers for quantifying greenhouse gas (GHG) emissions in Truro, NS. Utilized within this facility were three gas analyzers to monitor GHG emissions (CO2, N 2O, CH4) and the gaseous fluxes could then be determined using the mass balance micrometeorological technique. Prior to data collection, the site underwent testing to ensure valid conclusions and replicated responses from the wetland systems. Those wetlands receiving wastewater at a typical HLR (10.6 mm d-1) and with ample vegetation displayed the best concentration reductions. During the growing season (GS), average CO 2 consumption was large (approximately -44 g CO2m -2 d-1) for wetlands with dense vegetation (approximately 100% cover) at the typical loading rate. For those wetlands at higher loading rates, CO2 emissions were observed to be as high as +9.2 g CO 2m-2 d-1. Wetlands with typical loading rates and healthy aquatic vegetation produced average CH4 fluxes of approximately 43 g CO2 eq. m-2d-1, while higher loaded systems with little vegetation approached 90 g CO 2 eq. m-2d-1. During the non-growing season (NGS), all vegetated wetlands exhibited higher CH4 emissions than the non-vegetated systems (˜15 to 20% higher). Vegetation maturity played a strong role in the GHG balance. The average CO2consumption for wetlands with established vegetation was ˜ -36 g CO2 m -2 d-1 during the GS. Wetland 4, which had been newly transplanted in 2004, had the highest single day CO2 consumption of -152 g CO2m-2 d-1 . Methane emissions from wetlands with two-year-old vegetation followed the same pattern but were approximately half of the emissions recorded from 2003. The

  5. Constructed wetlands for wastewater treatment in cold climate - A review.

    PubMed

    Wang, Mo; Zhang, Dong Qing; Dong, Jian Wen; Tan, Soon Keat

    2017-07-01

    Constructed wetlands (CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option worldwide. However, the application of CW for wastewater treatment in frigid climate presents special challenges. Wetland treatment of wastewater relies largely on biological processes, and reliable treatment is often a function of climate conditions. To date, the rate of adoption of wetland technology for wastewater treatment in cold regions has been slow and there are relatively few published reports on CW applications in cold climate. This paper therefore highlights the practice and applications of treatment wetlands in cold climate. A comprehensive review of the effectiveness of contaminant removal in different wetland systems including: (1) free water surface (FWS) CWs; (2) subsurface flow (SSF) CWs; and (3) hybrid wetland systems, is presented. The emphasis of this review is also placed on the influence of cold weather conditions on the removal efficacies of different contaminants. The strategies of wetland design and operation for performance intensification, such as the presence of plant, operational mode, effluent recirculation, artificial aeration and in-series design, which are crucial to achieve the sustainable treatment performance in cold climate, are also discussed. This study is conducive to further research for the understanding of CW design and treatment performance in cold climate. Copyright © 2017. Published by Elsevier B.V.

  6. Modeling pollutant fate and transport in constructed wetlands

    SciTech Connect

    Brown, R.T.; Field, J.J.; Zanoli, M.J.; Crites, R.W.

    1994-12-31

    The Constructed Wetlands Fate and Aquatic Transport Evaluation Model (CWFATE) was developed to evaluate alternative design and operations of the constructed wetlands treatment system (CWTS) at the Sacramento Regional Wastewater Treatment Plant in Elk Grove, California. The model simulates the daily fate and transport of metals and other influent pollutants in an effort to predict CWTS effluent concentrations, removal efficiency, and long-term bioaccumulation of pollutants in sediment, vegetation, organic material, and aquatic organisms. Due to the difficulty of obtaining scientific information for model verification, final calibration is postponed until further field data become available.

  7. Removal of nutrients in various types of constructed wetlands.

    PubMed

    Vymazal, Jan

    2007-07-15

    The processes that affect removal and retention of nitrogen during wastewater treatment in constructed wetlands (CWs) are manifold and include NH(3) volatilization, nitrification, denitrification, nitrogen fixation, plant and microbial uptake, mineralization (ammonification), nitrate reduction to ammonium (nitrate-ammonification), anaerobic ammonia oxidation (ANAMMOX), fragmentation, sorption, desorption, burial, and leaching. However, only few processes ultimately remove total nitrogen from the wastewater while most processes just convert nitrogen to its various forms. Removal of total nitrogen in studied types of constructed wetlands varied between 40 and 55% with removed load ranging between 250 and 630 g N m(-2) yr(-1) depending on CWs type and inflow loading. However, the processes responsible for the removal differ in magnitude among systems. Single-stage constructed wetlands cannot achieve high removal of total nitrogen due to their inability to provide both aerobic and anaerobic conditions at the same time. Vertical flow constructed wetlands remove successfully ammonia-N but very limited denitrification takes place in these systems. On the other hand, horizontal-flow constructed wetlands provide good conditions for denitrification but the ability of these system to nitrify ammonia is very limited. Therefore, various types of constructed wetlands may be combined with each other in order to exploit the specific advantages of the individual systems. The soil phosphorus cycle is fundamentally different from the N cycle. There are no valency changes during biotic assimilation of inorganic P or during decomposition of organic P by microorganisms. Phosphorus transformations during wastewater treatment in CWs include adsorption, desorption, precipitation, dissolution, plant and microbial uptake, fragmentation, leaching, mineralization, sedimentation (peat accretion) and burial. The major phosphorus removal processes are sorption, precipitation, plant uptake (with

  8. Accumulation of Cd, Pb and Zn by 19 wetland plant species in constructed wetland.

    PubMed

    Liu, Jianguo; Dong, Yuan; Xu, Hai; Wang, Deke; Xu, Jiakuan

    2007-08-25

    Uptake and distribution of Cd, Pb and Zn by 19 wetland plant species were investigated with experiments in small-scale plot constructed wetlands, into which artificial wastewater dosed with Cd, Pb and Zn at concentrations of 0.5, 2.0 and 5.0mgl(-1) was irrigated. The results showed that the removal efficiency of Cd, Pb and Zn from the wastewater were more than 90%. Generally, there were tens differences among the 19 plant species in the concentrations and quantity accumulations of the heavy metals in aboveground part, underground part and whole plants. The distribution ratios into aboveground parts for the metals absorbed by plants varied also largely from about 30% to about 90%. All the plants accumulated, in one harvest, 19.85% of Cd, 22.55% of Pb and 23.75% of Zn that were added into the wastewater. Four plant species, e.g. Alternanthera philoxeroides, Zizania latifolia, Echinochloa crus-galli and Polygonum hydropiper, accumulated high amounts of Cd, Pb and Zn. Monochoria vaginalis was capable for accumulating Cd and Pb, Isachne globosa for Cd and Zn, and Digitaria sanguinalis and Fimbristylis miliacea for Zn. The results indicated that the plants, in constructed wetland for the treatment of wastewater polluted by heavy metals, can play important roles for removal of heavy metals through phytoextraction. Selection of plant species for use in constructed wetland will influence considerably removal efficiency and the function duration of the wetland.

  9. Removal of Pharmaceutical Products in a Constructed Wetland

    PubMed Central

    Özengin, Nihan; Elmaci, Ayse

    2016-01-01

    Background There is growing interest in the natural and constructed wetlands for wastewater treatment. While nutrient removal in wetlands has been extensively investigated, information regarding the degradation of the pharmaceuticals and personal care products (PPCPs) has only recently been emerging. PPCPs are widely distributed in urban wastewaters and can be removed to some extent by the constructed wetlands. The medium-term (3-5 years) behavior of these systems regarding PPCP removal is still unknown. Objectives The efficiency of a Leca-based laboratory-scale constructed wetland planted with Phragmites australis (Cav.) Trin. Ex. Steudel in treating an aqueous solution of the pharmaceuticals, namely, carbamazepine, ibuprofen, and sulfadiazine, was to investigate. Materials and Methods The two pilot-scale constructed wetlands (CW) were operated in parallel; one as an experimental unit (a planted reactor with P. australis) and the other as a control (an unplanted reactor with Leca). Pretreatment and analyses of the carbamazepine, ibuprofen, sulfadiazine, and tissue samples (Leca, P. australis body and P.australis leaf) were conducted using HPLC. Results The carbamazepine, ibuprofen, and sulfadiazine removal efficiencies for the planted and unplanted reactors were 89.23% and 95.94%, 89.50% and 94.73%, and 67.20% and 93.68%, respectively. The Leca bed permitted an efficient removal. Leca has a high sorption capacity for these pharmaceuticals, with removal efficiencies of 93.68-95.94% in the unplanted reactors. Conclusions Sorption processes might be of a major importance in achieving efficient treatment of wastewater, particularly in the removal of organic material that are resistant to biodegradation, in which case the materials composing the support matrix may play an important role. The results obtained in the present study indicate that a constructed wetland with Leca as a substrate and planted with P. australis is effective in the treatment of wastewater

  10. On the use of photothermal techniques for monitoring constructed wetlands

    NASA Astrophysics Data System (ADS)

    Gatts, C. E. N.; Faria, R. T.; Vargas, H.; Lannes, L. S.; Aragon, G. T.; Ovalle, A. R. C.

    2003-01-01

    Wetlands are a valued part of landscapes throughout the world. The steady increase of industrial facilities and disorganized urbanization processes, especially in developing countries, became a serious menace to these systems. The capability of wetlands to serve as a sink for nonpoint pollutants, particularly nutrients, is remarkable, but not limitless. For this reason, efforts to preserve them are considered a strategic issue for several countries. In addition, due to the exploding costs for sewage treatment, constructed wetlands for wastewater treatment (reed-bed systems) have been widely used under a variety of different conditions. Wetlands present unique characteristics related to biogeochemical cycles, the transport and transformation of chemicals due to interrelated physical, and chemical, and biological processes. Particularly, vegetated wetlands can act as a source for greenhouse gases through the emission of sediment-produced methane (CH4) to atmosphere. From studies concerning the behavior of Salvinia auriculata Aublet., we intend to demonstrate the potential use of photothermal techniques for monitoring gaseous emissions in wetlands.

  11. Macroinvertebrates Associated With Emergent Macrophyte Decomposition in a Constructed Wetland.

    NASA Astrophysics Data System (ADS)

    Nelson, M.; Thullen, J.; Sartoris, J.

    2005-05-01

    This study took place at the San Jacinto constructed wetland in California. Wetland water is supplied to irrigators in this cooperative venture between Reclamation and the Eastern Municipal Water District. One of the problems at this highly productive site is that plant litter accumulates to where it needs to be managed by taking the wetland off-line, thus impacting O&M costs and water delivery schedules for extended periods. Information on decomposition rates and conditions needed to encourage invertebrate decomposers was required to improve wetland reliability and decrease biomass management costs. Standing dead culms of bulrush (Schoenoplectus) were collected and air-dried to constant weight. Twenty-gram culm packs were placed in the wetland and then collected at two month intervals. Comparisons between fine-mesh and coarse-mesh packs demonstrated that exclusion of aquatic invertebrates decreased processing. This was also demonstrated in laboratory studies. It also appeared that culm pack decomposition rate varied with the macroinvertebrate community, and that community distribution was influenced by water quality. Study results confirm the importance of vegetation management through water management and wetland design. Maintaining healthy, sustainable ecosystems will help to encourage natural decomposition processes and maintain better water quality.

  12. Conservative and reactive solute transport in constructed wetlands

    USGS Publications Warehouse

    Keefe, S.H.; Barber, L.B.; Runkel, R.L.; Ryan, J.N.; McKnight, Diane M.; Wass, R.D.

    2004-01-01

    The transport of bromide, a conservative tracer, and rhodamine WT (RWT), a photodegrading tracer, was evaluated in three wastewater-dependent wetlands near Phoenix, Arizona, using a solute transport model with transient storage. Coupled sodium bromide and RWT tracer tests were performed to establish conservative transport and reactive parameters in constructed wetlands with water losses ranging from (1) relatively impermeable (15%), (2) moderately leaky (45%), and (3) significantly leaky (76%). RWT first-order photolysis rates and sorption coefficients were determined from independent field and laboratory experiments. Individual wetland hydraulic profiles influenced the extent of transient storage interaction in stagnant water areas and consequently RWT removal. Solute mixing and transient storage interaction occurred in the impermeable wetland, resulting in 21% RWT mass loss from main channel and storage zone photolysis (10%) and sorption (11%) reactions. Advection and dispersion governed solute transport in the leaky wetland, limiting RWT photolysis removal (1.2%) and favoring main channel sorption (3.6%). The moderately leaky wetland contained islands parallel to flow, producing channel flow and minimizing RWT losses (1.6%).

  13. Hydraulic characteristics of a constructed wetland: Implications for pollutant removal

    NASA Astrophysics Data System (ADS)

    Wachniew, P.; Czuprynski, P.; Maloszewski, P.; Ozimek, T.

    2003-04-01

    Constructed wetlands are built in order to treat wastewaters of various origin with some degree of control over purification processes. Treatment wetlands improve water quality through removal of suspended solids, organics, nitrogen, phosphorus, pathogens (bacteria, parasites, viruses) and metals. Transformation and removal of pollutants from wastewaters occur via numerous interrelated physical, chemical and biological processes. The efficiency of soluble pollutants removal is related to the degree of contact between wastewaters and the reactive surfaces. Therefore knowledge of hydraulic phenomena is crucial in studies of wetland functioning. A subsurface flow wetland in Nowa Slupia, Poland was studied in order to find out relationships between hydraulic phenomena and wetland performance. The wetland consists of three parallel gravel beds overgrown by common reed with a total surface area of 6400 sq m, total active volume of around 900 cubic m and the average loading of around 4 l/s. Three tracer tests with bromide and tritium accompanied by observations of water quality, plant distribution and biomass were performed in summer and winter conditions. Tracer breakthrough curves obtained from tracer tests were used to identify sub-systems within the wetland and to infer their hydraulic properties (water residence times, active volumes, dispersive characteristics). Three reed beds receive different wastewater loadings and show different water residence times and dispersive characteristics. Wastewater flow occurs partly via surface overflow with apparent stagnant zones and preferential flow pathways. These flow patterns are reflected in complex structure of breakthrough curves. Inhomogenous wastewater distribution within the wetland is due to operation practices and clogging of the gravel beds with refractory organic matter. Observations of effluent water quality, plant distribution and biomass reflect these apparent inhomogenities in wastewater flow patterns. This work

  14. Intensification of constructed wetlands for land area reduction: a review.

    PubMed

    Ilyas, Huma; Masih, Ilyas

    2017-03-11

    The large land area requirement of constructed wetlands (CWs) is a major limitation of its application especially in densely populated and mountainous areas. This review paper provides insights on different strategies applied for the reduction of land area including stack design and intensification of CWs with different aeration methods. The impacts of different aeration methods on the performance and land area reduction were extensively and critically evaluated for nine wetland systems under three aeration strategies such as tidal flow (TF), effluent recirculation (ER), and artificial aeration (AA) applied on three types of CWs including vertical flow constructed wetland (VFCW), horizontal flow constructed wetland (HFCW), and hybrid constructed wetland (HCW). The area reduction and pollutant removal efficiency showed substantial variation among different types of CWs and aeration strategies. The ER-VFCW designated the smallest footprint of 1.1 ± 0.5 m(2) PE(-1) (population equivalent) followed by TF-VFCW with the footprint of 2.1 ± 1.8 m(2) PE(-1), and the large footprint was of AA-HFCW (7.8 ± 4.7 m(2) PE(-1)). When footprint and removal efficiency both are the major indicators for the selection of wetland type, the best options for practical application could be TF-VFCW, ER-HCW, and AA-HCW. The data and results outlined in this review could be instructive for futures studies and practical applications of CWs for wastewater treatment, especially in land-limited regions.

  15. Effectiveness of mitigation measures with constructed forested wetlands in Maryland

    USGS Publications Warehouse

    Perry, M.C.

    1997-01-01

    Intensive research on six constructed forested wetlands in Central Maryland was conducted in 1993-1996 to determine success of these habitats as functional forested wetlands for wildlife. Areas studied ranged in size from 2 to 35 acres and were constructed by private companies under contract with three mitigation agencies. Adjacent natural forested wetlands were used as reference sites where similar data were collected. Based on data from the first four years of this study it appears that it will take 35-50 years before these areas have forested wetland vegetation and wildlife similar to that found on mature forested wetlands. This long-time period is based on the high mortality and slow growth of nursery-stock trees and shrubs transplanted on the areas. Mortality and slow growth resulted mostly from excessive surface water on the sites. The level of ground water did not appear to be a factor in regard to transplant mortality. Green ash was the woody transplant species that had the least mortality. Sampling of vegetative ground cover with one-meter square quadrats showed the predominance of grasses and herbs. [abridged abstract

  16. Mitigation of methane emissions from constructed farm wetlands.

    PubMed

    Pangala, Sunitha R; Reay, David S; Heal, Kate V

    2010-01-01

    Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH(4). The effect of addition of two potential inhibitors of methanogenesis - iron ochre and gypsum - on net CH(4) emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH(4) fluxes from three 15-m(2) wetland plots were measured between January and July 2008 in large static chambers incorporating a tunable diode laser, with application of 5tonha(-1) ochre and gypsum in May. CH(4) fluxes were also measured from control and ochre- and gypsum-treated wetland sediment cores incubated at constant and varying temperature in the laboratory. Ochre addition suppressed CH(4) emissions by 64+/-13% in the field plot and >90% in laboratory incubations compared to controls. Gypsum application of 5tonha(-1) in the field and laboratory experiments had no effect on CH(4) emissions, but application of 10tonha(-1) to a sediment core reduced CH(4) emissions by 28%. Suppression of CH(4) emissions by ochre application to sediment cores also increased with temperature; the reduction relative to the control increased from 50% at 17.5 degrees C to >90% at 27.5 degrees C. No significant changes in N removal or pH and potentially-toxic metal content of sediments as the result of inhibitor application were detected in the wetland during the study.

  17. Biological diversity versus risk for mosquito nuisance and disease transmission in constructed wetlands in southern Sweden.

    PubMed

    Schäfer, M L; Lundström, J O; Pfeffer, M; Lundkvist, E; Landin, J

    2004-09-01

    In southern Sweden, many wetlands have been constructed, and maintaining or increasing biological diversity is often included in the aims. Some wetlands are constructed near human settlements, thus raising the problem of wetlands being associated with mosquitoes (Diptera: Culicidae). Increased biodiversity (including mosquito diversity) is considered desirable, whereas mosquito nuisance from a human point of view is not. Adult mosquito abundance, diversity and species assemblages of constructed wetlands were compared to natural wetlands. The potential of constructed wetlands for mosquito nuisance and transmission of mosquito-borne viruses was evaluated. The study areas included five constructed and four natural wetlands. Mosquito abundance and species richness were higher in the natural than in the constructed wetlands, and showed a positive correlation with wetland size. Mosquito species assemblages formed three clusters, which were not explained by origin, size and water permanence of wetlands. In a redundancy analysis, however, mosquito faunas showed significant relationships with these variables, and size and origin of wetlands were most important. Major nuisance species (multivoltine species feeding on mammals and laying eggs on soil) were found in all wetlands, although in relatively low numbers. Risk assessment for Sindbis virus transmission showed moderate risk for two constructed wetlands near human settlements. It is concluded that small size of constructed wetlands has the advantage of low mosquito numbers from a human point of view. The use of functional groups is recommended as a tool for presenting mosquito data to the public, and for helping communication between scientists and administrative decision makers.

  18. Effect of treatment in a constructed wetland on toxicity of textile wastewater

    USGS Publications Warehouse

    Baughman, G.L.; Perkins, W.S.; Lasier, P.J.; Winger, P.V.

    2003-01-01

    Constructed wetlands for treating wastewater have proliferated in recent years and their characteristics have been studied extensively. In most cases, constructed wetlands have been used primarily for removal of nutrients and heavy metals. Extensive literature is available concerning construction and use of wetlands for treatment of wastewater. Even so, quantitative descriptions of wetland function and processes are highly empirical and difficult to extrapolate. The processes involved in removal of pollutants by wetlands are poorly understood, especially for waste streams as complex as textile effluents. The few studies conducted on treatment of textile wastewater in constructed wetlands were cited in earlier publications. Results of a two-year study of a full-scale wetland treating textile effluent are presented here. The paper describes the effects of the wetland on aquatic toxicity of the wastewater and draws conclusions about the utility and limitations of constructed wetlands for treatment of textile effluents.

  19. INVENTORY OF CONSTRUCTED WETLANDS IN THE UNITED STATES

    EPA Science Inventory

    During 1990 and 1991 the U.S. Environmental Production Agency (EPA) sponsored an effort to identify existing and planned constructed wetlands in the U.S. and to collect readily available information from operating systems. In addition to inquiries by telephone and mail, the effor...

  20. ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE TECHNOLOGY CAPSULE

    EPA Science Inventory

    In fall 1994, anaerobic compost wetlands in both upflow and down flow configurations were constructed adjacent to and received drainage from the Burleigh tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The ...

  1. ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE ITER

    EPA Science Inventory

    In Fall 1994, anaerobic compost wetlands in both upflow and downflow configurations were constructed adjacent to and received drainage from the Burleigh Tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The e...

  2. Spatial distribution of metals in the constructed wetlands.

    PubMed

    Kongroy, Porntawee; Tantemsapya, Netnapid; Lin, Ying-Feng; Jing, Shuh Ren; Wirojanagud, Wanpen

    2012-02-01

    Investigation of the spatial distribution of metals was conducted for two constructed wetlands used as tertiary treatment in Chia Nan University of Pharmacy and Science (CNU) and Metal Processing Industries (MPI) located in Tainan, Taiwan. These two distinguished sites were selected to compare the distribution of metals for constructed wetlands treating different types of wastewater. Along the distance, samples of water, sediment, and macrophytes were analyzed for metals including Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Additionally, measurements of water quality including temperature, pH, EC, ORP, DO, TSS, BOD, COD, and turbidity were performed. Results show that, at CNU, wastewater contained higher organic consititute (BOD 29.3 +/- 11.7 mg/, COD 46.7 +/- 33.6 mg/L) with low metals content. Wastewater at MPI contained low level of organic consititute (BOD 7.1 +/- 3.3 mg/L, and COD 66.0 +/- 56.5 mg/L) and higher metals content. Metals distribution of both sites showed similar results where metals in the sediments in the inlet zone have greater concentrations than other areas. The constructed wetlands can remove Cd, Cu, Ni, Pb, and Zn. However, there was no removal of Al, Cr, Fe, and Mn. A distance along the constructed wetlands had no effect on metal concentrations in macrophyte and water.

  3. Evaluation of constructed wetland treatment performance for winery wastewater.

    PubMed

    Grismer, Mark E; Carr, Melanie A; Shepherd, Heather L

    2003-01-01

    Rapid expansion of wineries in rural California during the past three decades has created contamination problems related to winery wastewater treatment and disposal; however, little information is available about performance of on-site treatment systems. Here, the project objective was to determine full-scale, subsurface-flow constructed wetland retention times and treatment performance through assessment of water quality by daily sampling of total dissolved solids, pH, total suspended solids, chemical oxygen demand (COD), tannins, nitrate, ammonium, total Kjeldahl nitrogen, phosphate, sulfate, and sulfide across operating systems for winery wastewater treatment. Measurements were conducted during both the fall crush season of heavy loading and the spring following bottling and racking operations at the winery. Simple decay model coefficients for these constituents as well as COD and tannin removal efficiencies from winery wastewater in bench-scale reactors are also determined. The bench-scale study used upward-flow, inoculated attached-growth (pea-gravel substrate) reactors fed synthetic winery wastewater. Inlet and outlet tracer studies for determination of actual retention times were essential to analyses of treatment performance from an operational subsurface-flow constructed wetland that had been overloaded due to failure to install a pretreatment system for suspended solids removal. Less intensive sampling conducted at a smaller operational winery wastewater constructed wetland that had used pretreatment suspended solids removal and aeration indicated that the constructed wetlands were capable of complete organic load removal from the winery wastewater.

  4. ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE ITER

    EPA Science Inventory

    In Fall 1994, anaerobic compost wetlands in both upflow and downflow configurations were constructed adjacent to and received drainage from the Burleigh Tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The e...

  5. ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE TECHNOLOGY CAPSULE

    EPA Science Inventory

    In fall 1994, anaerobic compost wetlands in both upflow and down flow configurations were constructed adjacent to and received drainage from the Burleigh tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The ...

  6. Ciliate communities in a constructed mangrove wetland for wastewater treatment.

    PubMed

    Chen, Qing-Hua; Tam, Nora Fung-Yee; Shin, Paul K S; Cheung, Siu-Giu; Xu, Run-Lin

    2009-05-01

    In wetlands constructed for treating municipal and industrial wastewater, including mangroves, the effect of wastewater discharged on the substrate has often been neglected. Ciliates, an important group of protozoa, are sensitive to pollutants and any changes in ciliate diversity and community structure reflects the habitat quality. The ciliate communities at six sections along a constructed mangrove belt (33 m in length) planted with Aegicerascorniculatum were investigated in Shenzhen, South China. In all samples collected in both rainy and dry seasons, 183 ciliate species were observed. Most species (56%) were free-swimming forms, while only 10.8% were sessile ciliates. The abundance and species number of ciliates were both found to decrease from the anterior (the wastewater inlet) to the posterior (the outlet) parts of the wetland belt, indicating that organic matter and bacteria in wastewater, which served as food for most ciliates, were gradually removed by the constructed wetland. The r/K (number of r- and K-selected species) ratios at the six sections were relatively small, between 0.2 and 0.4, whereas the C/P (abundance of colpodids and polyhymenophorans) quotient at some sections was higher than 1. These results indicate that although most of the environments along the constructed wetland belt were not stressful for ciliate communities, there were habitats that favored colpodids in high abundances.

  7. Hydrology and hydraulics of treatment wetlands constructed on drained peatlands

    NASA Astrophysics Data System (ADS)

    Postila, Heini; Ronkanen, Anna-Kaisa; Kløve, Bjørn

    2013-04-01

    Treatment wetlands are globally used for wastewater purification purposes. In Finland, these wetlands are commonly peatland-based and are used to treat runoff from peat extraction sites and peatland forestry. Wetlands are also used for polishing municipal wastewaters and mining waters. In peat extraction the structures are usually called overland flow areas (OFAs), which are traditionally established on pristine peatlands. However, nowadays establishing of new peat extraction sites is guided to drained peatland areas due to the Finnish Peat Use Strategy, which leads difficulties to find undisturbed peatland area for OFA. Therefore treatment wetlands have had to construct also on drained peatland areas. In drained areas peat physical properties have changed due to oxidation and subsidence and the water flow pathways differs from OFAs flow patterns, which maybe have effect on purification results. Thus in the present study we aim to clarify the hydrology and hydraulic properties of treatment wetlands constructed on drained peatland areas. For this purposes, 20 treatment wetlands on drained peatland areas across Finland were detailed measured for peat hydraulic conductivity. In selected areas, runoff was continuously monitored, flow distribution at treatment areas was studied and water residence times measured with tracer tests using potassium iodide (KI). Generally, in the study areas, the ditches had been completely blocked, partly blocked e.g with peat dams or not blocked at all. The ditches were located partly parallel to the flow direction and partly perpendicular to it. The distribution of water to the wetlands has been implemented in many different ways e.g. by distribution ditch or by perforated pipes. Based on the results, in majority of the wetlands, the peat drainage has clearly affected the hydraulic properties of wetlands, but not on all sites. In more than half of the wetlands (12), the median hydraulic conductivity of peat drastically decreased at the

  8. Constructed wetlands for wastewater treatment: five decades of experience.

    PubMed

    Vymazal, Jan

    2011-01-01

    The first experiments on the use of wetland plants to treat wastewaters were carried out in the early 1950s by Dr. Käthe Seidel in Germany and the first full-scale systems were put into operation during the late 1960s. Since then, the subsurface systems have been commonly used in Europe while free water surface systems have been more popular in North America and Australia. During the 1970s and 1980s, the information on constructed wetland technology spread slowly. But since the 1990 s the technology has become international, facilitated by exchange among scientists and researchers around the world. Because of the need for more effective removal of ammonia and total nitrogen, during the 1990 s and 2000s vertical and horizontal flow constructed wetlands were combined to complement each other to achieve higher treatment efficiency. Today, constructed wetlands are recognized as a reliable wastewater treatment technology and they represent a suitable solution for the treatment of many types of wastewater.

  9. compartment transfer rates in horizontal flow constructed wetlands

    NASA Astrophysics Data System (ADS)

    Maier, Uli; Oswald, Sascha; Thullner, Martin; Grathwohl, Peter

    2010-05-01

    A conceptual computer model has been constructed to simulate the compartment transfer rates in horizontal flow constructed wetlands. The model accounts for flow and transport in the variably saturated porous medium as well as biogeochemical change reactions. The most concentrated contaminants such as BTEX, MTBE and gasoline hydrocarbons and dissolved as well as mineral phase electron acceptors are considered. Also of major interest are reduced species with high oxygen demand such as ammonium. The influence of marsh plants on microbial activity, gas transport, water balance and contaminant fate in general is matter of current investigation. The constructed wetlands consist of a coarse sand or fine gravel porous medium. Marsh plants were introduced after installation, however, a number of control basins are operated unplanted. Water levels and through flow rates are adjusted to optimize the remediation efficiency. The system is likely to be neither reaction nor mixing limited, thus both, values of dispersivity and degradation kinetics may be crucial for remediation efficiency. Biogeochemical modelling is able to delineate in detail (i) the zonation of processes, (ii) temporal variation (breakthrough curves) and (iii) mass balance information. The contributions of biodegradation and volatilisation and the influence of plants (compartment transfer) can generally best be evaluated by the component's mass balance. More efficient mixing is expected in the wetlands with open water body which leads to both, more biodegradation and volatilisation. An important task is to quantify the role of plants and root systems for contaminant attenuation in constructed wetlands. The long term goal of investigation is to allow for predictions for the design of large scale compartment transfer wetlands that may be applied to remediate the site as a whole.

  10. Phytotoxicity testing of winery wastewater for constructed wetland treatment.

    PubMed

    Arienzo, Michele; Christen, Evan W; Quayle, Wendy C

    2009-09-30

    Rapid and inexpensive phytotoxicity bioassays for winery wastewater (WW) are important when designing winery wastewater treatment systems involving constructed wetlands. Three macrophyte wetland species (Phragmites australis, Schoenoplectus validus and Juncus ingens) were tested using a pot experiment simulating a wetland microcosm. The winery wastewater concentration was varied (0.5%, 5%, 10%, 25%, 50%, 75% and 100%) and pH was corrected for some concentrations using lime as an amendment. The tolerance of the three aquatic macrophytes species to winery wastewater was studied through biomass production, total chlorophyll and nitrogen, phosphorous and potassium tissue concentrations. The results showed that at greater than 25% wastewater concentration all the macrophytes died and that Phragmites was the least hardy species. At less than 25% wastewater concentration the wetland microcosms were effective in reducing chemical oxygen demand, phenols and total soluble solids. We also evaluated the performance of two laboratory phytotoxicity assays; (1) Garden Cress (Lepidium sativum), and (2) Onion (Allium coepa). The results of these tests revealed that the effluent was highly toxic with effective concentration, EC(50), inhibition values, as low as 0.25%. Liming the WW increased the EC(50) by 10 fold. Comparing the cress and onion bioassays with the wetland microcosm results indicated that the thresholds for toxicity were of the same order of magnitude. As such we suggest that the onion and cress bioassays could be effectively used in the wine industry for rapid wastewater toxicity assessment.

  11. Triclosan removal in wetlands constructed with different aquatic plants.

    PubMed

    Liu, Jianing; Wang, Jingmin; Zhao, Congcong; Hay, Anthony G; Xie, Huijun; Zhan, Jian

    2015-10-22

    Triclosan (TCS) is widely used in consumer products as an antimicrobial agent. Constructed wetlands have the potential for TCS removal, but knowledge about the relative importance of sediment, plants, and microbes is limited. TCS removal performance was investigated in well-operated constructed wetlands planted with three different types of aquatic plants: emergent Cattail (C-T), submerged Hornwort (H-T), and floating Lemnaminor (L-T). Results showed that the TCS removal efficiencies from water were all greater than 97 %. Maximal TCS adsorption to sediment in the C-T wetland (13.8 ± 0.6 ng/g) was significantly lower than in the H-T wetland (21.0 ± 0.3 ng/g) or the L-T wetland (21.4 ± 0.6 ng/g). The maximal TCS concentrations in plants were 5.7 ± 0.2 and 7.2 ± 0.5 μg/g for H-T and L-T, respectively, and it was below the minimal detection limit (MDL) in C-T. Deep 16S rRNA gene sequencing results revealed that C-T wetland had the highest community richness and diversity. Some bacteria, like beta-Proteobacteria, gamma-Proteobacteria, and Bacteroidetes were detected and might have significant correlations with TCS degradation. Overall, with regard to soils, plants, and microorganism, accumulation in sediment and plants in H-T and L-T was high, while in C-T biodegradation likely played an important role.

  12. Influence of UV radiation on chlorophyll, and antioxidant enzymes of wetland plants in different types of constructed wetland.

    PubMed

    Xu, Defu; Wu, Yinjuan; Li, Yingxue; Howard, Alan; Jiang, Xiaodong; Guan, Yidong; Gao, Yongxia

    2014-09-01

    A surface- and vertical subsurface-flow-constructed wetland were designed to study the response of chlorophyll and antioxidant enzymes to elevated UV radiation in three types of wetland plants (Canna indica, Phragmites austrail, and Typha augustifolia). Results showed that (1) chlorophyll content of C. indica, P. austrail, and T. augustifolia in the constructed wetland was significantly lower where UV radiation was increased by 10 and 20 % above ambient solar level than in treatment with ambient solar UV radiation (p < 0.05). (2) The malondialdehyde (MDA) content, guaiacol peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities of wetland plants increased with elevated UV radiation intensity. (3) The increased rate of MDA, SOD, POD, and CAT activities of C. indica, P. australis, and T. angustifolia by elevated UV radiation of 10 % was higher in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. The sensitivity of MDA, SOD, POD, and CAT activities of C. indica, P. austrail, and T. augustifolia to the elevated UV radiation was lower in surface-flow-constructed wetland than in the vertical subsurface-flow-constructed wetland, which was related to a reduction in UV radiation intensity through the dissolved organic carbon and suspended matter in the water. C. indica had the highest SOD and POD activities, which implied it is more sensitive to enhanced UV radiation. Therefore, different wetland plants had different antioxidant enzymes by elevated UV radiation, which were more sensitive in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland.

  13. Bacterial activity in plant (Schoenoplectus validus) biofilms of constructed wetlands.

    PubMed

    Pollard, Peter C

    2010-12-01

    Biofilm-bacterial communities have been exploited in the treatment of wastewater in 'fixed-film' processes. Our understanding of biofilm dynamics requires a quantitative knowledge of bacterial growth-kinetics in these microenvironments. The aim of this paper was to apply the thymidine assay to quantify bacterial growth without disturbing the biofilm on the surfaces of emergent macrophytes (Schoenoplectus validus) of a constructed wetland. The isotope was rapidly and efficiently taken-up and incorporated into dividing biofilm-bacteria. Isotope diffusion into the biofilm did not limit the growth rate measurement. Isotope dilution was inhibited at >12 μM thymidine. Biofilm-bacterial biomass and growth rates were not correlated to the plant surface area (r(2) < 0.02). The measurements of in situ biofilm-bacterial growth rates both displayed, and accommodated, the inherent heterogeneity of the complex wetland ecosystem. Biofilm-bacterial respiratory activities, measured using the redox dye CTC, and growth rates were measured simultaneously. The dye did not interfere with bacterial growth. Biofilm-bacterial specific growth rates ranged from 1.4 ± 0.6 d(-1) to 3.3 ± 1.3 d(-1). In the constructed wetlands of this study biofilm-bacterial specific growth rates, compared to those of natural ecosystems, could be markedly improved through changes in wetland design that increased bacterial respiration while minimising biofilm growth.

  14. Reciprocating constructed wetlands for treating industrial, municipal and agricultural wastewater.

    PubMed

    Behrends, L; Houke, L; Bailey, E; Jansen, P; Brown, D

    2001-01-01

    Scientists at the Tennessee Valley Authority (TVA), and in collaboration with the U.S. Environmental Protection Agency (EPA), are continuing to develop and refine an innovative wastewater treatment system referred to as reciprocating subsurface-flow constructed wetlands. Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands, such that contiguous cells are filled and drained on a frequent and recurrent basis. This operating technique turns the entire wetland system into a fixed-film biological reactor, in which it is possible to control redox potential in alternating aerobic and anaerobic zones. Reciprocating systems enable manipulation of wastewater treatment functions by controlling such parameters as hydraulic retention time, frequency of reciprocation, reciprocation cycle time, depth of reciprocation, and size and composition of substrate. These improved wetland technologies have been used for treating municipal/domestic wastewater, high strength animal wastewater, and mixed wastewater streams containing acids, recalcitrant compounds, solvents, antifreeze compounds, heavy metals, explosives, and fertilizer nutrients. Results from selected treatability studies and field demonstrations will be summarized with respect to conceptual design and treatment efficacy.

  15. Microbial and vegetative changes associated with development of a constructed wetland

    USDA-ARS?s Scientific Manuscript database

    Wetlands may be constructed to provide several ecosystem functions. A constructed wetland receiving agricultural runoff water was observed prior to, and for more than two years after, establishment. The excavated portion of this wetland was compared to an undisturbed, upland area and to an adjacent...

  16. Effect of earthworm Eisenia fetida and wetland plants on nitrification and denitrification potentials in vertical flow constructed wetland.

    PubMed

    Xu, Defu; Li, Yingxue; Howard, Alan; Guan, Yidong

    2013-06-01

    The response of nitrification potentials, denitrification potentials, and N removal efficiency to the introduction of earthworms and wetland plants in a vertical flow constructed wetland system was investigated. Addition of earthworms increased nitrification and denitrification potentials of substrate in non-vegetated constructed wetland by 236% and 8%, respectively; it increased nitrification and denitrification potentials in rhizosphere in vegetated constructed wetland (Phragmites austrail, Typha augustifolia and Canna indica), 105% and 5%, 187% and 12%, and 268% and 15% respectively. Denitrification potentials in rhizosphere of three wetland plants were not significantly different, but nitrification potentials in rhizosphere followed the order of C. indica>T. augustifolia>P. australis when addition of earthworms into constructed wetland. Addition of earthworms to the vegetated constructed significantly increased the total number of bacteria and fungi of substrates (P<0.05). The total number of bacteria was significantly correlated with nitrification potentials (r=913, P<0.01) and denitrification potentials (r=840, P<0.01), respectively. The N concentration of stems and leaves of C. indica were significantly higher in the constructed wetland with earthworms (P<0.05). Earthworms had greater impact on nitrification potentials than denitrification potentials. The removal efficiency of N was improved via stimulated nitrification potentials by earthworms and higher N uptake by wetland plants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Application of a constructed wetland system for polluted stream remediation

    NASA Astrophysics Data System (ADS)

    Tu, Y. T.; Chiang, P. C.; Yang, J.; Chen, S. H.; Kao, C. M.

    2014-03-01

    In 2010, the multi-function Kaoping River Rail Bridge Constructed Wetland (KRRBW) was constructed to improve the stream water quality and rehabilitate the ecosystem of the surrounding environment of Dashu Region, Kaohsiung, Taiwan. The KRRBW consists of five wetland basins with a total water surface area of 15 ha, a total hydraulic retention time (HRT) of 10.1 days at a averaged flow rate of 14 740 m3/day, and an averaged water depth of 1.1 m. The influent of KRRBW coming from the local drainage systems containing untreated domestic, agricultural, and industrial wastewaters. Based on the quarterly investigation results of water samples taken in 2011-2012, the overall removal efficiencies were 91% for biochemical oxygen demand (BOD), 75% for total nitrogen (TN), 96% for total phosphorus (TP), and 99% for total coliforms (TC). The calculated first-order decay rates for BOD, TN, TP, NH3-N, and TC ranged from 0.14 (TN) to 0.42 (TC) 1/day. This indicates that the KRRBW was able to remove organics, TC, and nutrients effectively. The high ammonia/nitrate removal efficiency indicates that nitrification and denitrification processes occurred simultaneously in the wetland system, and the detected nitrite concentration confirmed the occurrence of denitrification/nitrification. Results from sediment analyses reveal that the sediment contained high concentrations of organics (sediment oxygen demand = 1.9-5.2 g O2/m2 day), nutrients (up to 15.8 g total nitrogen/kg of sediment and 1.48 g total phosphorus/kg of sediment), and metals (up to 547 mg/kg of Zn and 97 mg/kg of Cu). Appropriate wetland management strategies need to be developed to prevent the release of contaminants into the wetland system. The wetland system caused the variations in the microbial diversities and dominant microbial bacteria. Results show the dominant nitrogen utilization bacteria including Denitratisoma oestradiolicum, Nitrosospira sp., Nitrosovibrio sp., D. oestradiolicum, Alcaligenes sp

  18. A LOW-COST THREE-DIMENSIONAL SAMPLE COLLECTION ARRAY TO EVALUATE AND MONITOR CONSTRUCTED WETLANDS

    USDA-ARS?s Scientific Manuscript database

    Artificially constructed wetlands are gaining acceptance as a low cost treatment alternative to remove a number of undesirable constituents from water. Wetlands can be used to physically remove compounds such as suspended solids through sedimentation. Dissolved nutrients, biochemical oxygen demand, ...

  19. Study of constructed wetlands effluent disinfected with ozone.

    PubMed

    Miranda, N D; Oliveira, E L; Silva, G H R

    2014-01-01

    The purpose of this research was to study the disinfection of sanitary effluent from constructed wetlands, evaluating the oxidation of organic matter, the formation of formaldehyde, as well as the efficiency of total coliforms and Escherichia coli inactivation. A constant flow of ozone was applied to the batch system in 5 and 10 mg.O3 L(-1) doses with contact times of 5 and 10 min. This study revealed that the average values of formaldehyde formation ranged between 259.00 and 379.00 μg L(-1), which means that the values are within World Health Organization recommended values. The total coliforms and E. coli showed complete inactivation in almost all tests. The dose of ozone 5 mg.O3 L(-1) and contact time of 5 min were sufficient for a significant reduction of the concentration levels of pathogens in constructed wetlands effluent with similar characteristics, thus allowing for its agricultural reuse.

  20. FUNDAMENTAL INVESTIGATION ON CONSTRUCTED WETLAND DESIGN FOR WASTE WATER PURIFICATION

    NASA Astrophysics Data System (ADS)

    Ishikawa, Tadaharu; Gao, Shuang

    In designing a constructed wetland for water purification, a homogeneous vegetation bed is often adopted in order to prevent short circuit which reduces the efficiency of SS trapping. However, vegetation naturally becomes inhomogeneous under the action of water flow, causing unexpected short circuit. This paper discusses a possibility to design a channel for a "stable short circuit", which distributes SS to vegetation zones by large horizontal eddies between the channel and vegetation zones. A series of numerical experiments show that even one slightly bended channel can distribute a high ratio of SS supplied through the channel to vegetation zones with the aid of horizontal eddies. This fact suggests that hydraulic design of artificial short circuit can be an alternative strategy for design of constructed wetlands.

  1. Disinfection capacity of seven constructed wetlands and ponds.

    PubMed

    Rühmland, S; Barjenbruch, M

    2013-01-01

    The disinfection performance of three subsurface flow constructed wetlands (SSF), a free-water surface-constructed wetland and three ponds were investigated. They functioned as advanced treatment stage following treatment in a large municipal wastewater treatment plant equipped with nutrient removal. Despite low influent concentrations of 10(3.9)/100 mL, Escherichia coli underwent a reduction of 1.7 (ditch) to 2.3 (sandy loamy SSF) orders of magnitude. After passing through these treatment plants E. coli was lowered sufficiently to within the permitted levels thus allowing it to be used in drip irrigation of fruits and vegetables. The change of seasons and hydraulic loading (in the range of 50-150 mm/day) as well as short-term overloadings did not impact the effluents' quality.

  2. Removal of Selected Metals from Wastewater Using a Constructed Wetland.

    PubMed

    Šíma, Jan; Svoboda, Lubomír; Pomijová, Zuzana

    2016-05-01

    Removal of selected metals from municipal wastewater using a constructed wetland with a horizontal subsurface flow was studied. The objective of the work was to determine the efficiency of Cu, Zn, Ni, Co, Sr, Li, and Rb removal, and to describe the main removal mechanisms. The highest removal efficiencies were attained for zinc and copper (89.8 and 81.5%, respectively). It is apparently due to the precipitation of insoluble sulfides (ZnS, CuS) in the vegetation bed where the sulfate reduction takes place. Significantly lower removal efficiencies (43.9, 27.7, and 21.5%) were observed for Li, Sr, and Rb, respectively. Rather, low removal efficiencies were also attained for Ni and Co (39.8 and 20.9%). However, the concentrations of these metals in treated water were significantly lower compared to Cu and Zn (e.g., 2.8 ± 0.5 and 1.7 ± 0.3 μg/l for Ni at the inflow and outflow from the wetland compared to 27.6 ± 12.0 and 5.1 ± 4.7 μg/l obtained for Cu, respectively). The main perspective of the constructed wetland is the removal of toxic heavy metals forming insoluble compounds depositing in the wetland bed. Metal uptake occurs preferentially in wetland sediments and is closely associated with the chemism of sulfur and iron. © 2016 Verlag Helvetica Chimica Acta AG, Zürich.

  3. Nitrogen dynamics in a constructed wetland system treating landfill leachate.

    PubMed

    Kinsley, C B; Crolla, A M; Kuyucak, N; Zimmer, M; Laflèche, A

    2007-01-01

    A pilot scale treatment system was established in 2002 at the Laflèche Landfill in Eastern Ontario, Canada. The system consists of a series of treatment steps: a stabilisation basin (10,000 m3), a woodland peat trickling filter (5,200 m2), a subsurface flow constructed wetland planted in Phragmites sp. (2,600 m2), a surface flow constructed wetland planted in Typha sp. (3,600 m2) and a polishing pond (3,600 m2). The system operates from May to December with leachate being recycled within the landfill during the winter months. Hydraulic loading was increased three-fold over four operating seasons with nitrogen and organic mass loading increasing six-fold. Excellent removal efficiencies were observed with 93% BOD5, 90% TKN and 97% NH4-N removed under the highest loading conditions. Almost complete denitrification was observed throughout the treatment system with NO3-N concentrations never exceeding 5mg L(-1). The peat filter reached treatment capacity at a hydraulic loading of 4cm d(-1) and organic loading rate of 42 kg BOD ha(-1) d(-1), which is consistent with design criteria for vertical flow wetland systems and intermittent sand filters, The first order plug flow kinetic model was effective at describing TKN and ammonium removal in the SSF and FWS wetlands when background concentrations were taken into account. Ammonium removal k-values were consistent with the literature at 52.6 and 57.7 yr(-1) for the SSF and FWS wetlands, respectively, while TKN k-values at 6.9 and 7.7 yr(-1) were almost an order of magnitude lower than literature values, suggesting that leachate TKN could contain refractory organics not found in domestic wastewater.

  4. Municipal wastewater treatment with pond-constructed wetland system: a case study.

    PubMed

    Wang, X; Bai, X; Qiu, J; Wang, B

    2005-01-01

    The performance of a pond-constructed wetland system in the treatment of municipal wastewater in Kiaochow city was studied; and comparison with oxidation ponds system was conducted. In the post-constructed wetland, the removal of COD, TN and TP is 24%, 58.5% and 24.8% respectively. The treated effluent from the constructed wetland can meet the Chinese National Agricultural and Irrigation Standard. The comparison between pond-constructed wetland system and oxidation pond system shows that total nitrogen removal in a constructed wetland is better than that in an oxidation pond and the TP removal is inferior. A possible reason is the low dissolved oxygen concentration in the wetland. Constructed wetlands can restrain the growth of algae effectively, and can produce obvious ecological and economical benefits.

  5. Constructed wetland treatment system in textile industry and sustainable development.

    PubMed

    Davies, L C; Pedro, I S; Ferreira, R A; Freire, F G; Novais, J M; Martins-Dias, S

    2008-01-01

    This study focuses on the evaluation of the adequacy and sustainability of a constructed wetland (CW), with vertical flow (VF) design to treat a strongly coloured textile wastewater.Secondly an accidental AO7 overloaded discharge (700 mg l(-1)) was studied. A set of three similar VFCW beds (3x1 m2), operating in series, allowed also the efficient treatment of the AO7 heavy loaded wastewaters. The treated effluent quality enables water reuse for irrigation purposes or within the process.

  6. Groundwater Flow Through a Constructed Treatment Wetland

    DTIC Science & Technology

    2002-03-01

    state conditions. Various methods for analyzing transient time-drawdown data from aquifer pump tests exist in the literature. Many employ a curve...Huang, for the many patient hours of instruction and support with the numerical modeling portion of this thesis; without your help, my product...Recommendations for Further Study ................. 5-5 Appendix A: Piezometer Grid and Construction Data ....... A-1 Appendix B: Contours of

  7. Characterisation of the soil bacterial community structure and composition of natural and constructed wetlands.

    PubMed

    Ansola, Gemma; Arroyo, Paula; Sáenz de Miera, Luis E

    2014-03-01

    In the present study, the pyrosequencing of 16S ribosomal DNA was used to characterise the soil bacterial community composition of a constructed wetland receiving municipal wastewater and a nearby natural wetland. Soil samples were taken from different locations in each wetland (lagoon, zone with T. latifolia, zone with S. atrocinerea). Moreover, the water quality parameters were evaluated (pH, Tª, conductivity, dissolved oxygen, redox potential, nutrients and suspended solids), revealing that the organic matter and nutrient contents were significantly higher in the constructed wetland than in the natural one. In general, the bacterial communities of the natural wetland were more diverse than those of the constructed wetland. The major phylogenic groups of all soils included Proteobacteria, Verrucomicrobia and Chloroflexi, with Proteobacteria being the majority of the community composition. The Verrucomicrobia and Chloroflexi phyla were more abundant in the natural wetland than the constructed wetland; in contrast, the Proteobacteria phylum was more abundant in the constructed wetland than the natural wetland. Beta diversity analyses reveal that the soil bacterial communities in the natural wetland were less dissimilar to each other than to those of the constructed wetland.

  8. Nitrogen management in reservoir catchments through constructed wetland systems.

    PubMed

    Tunçiper, B; Ayaz, S C; Akça, L; Samsunlu, A

    2005-01-01

    In this study, nitrogen removal was investigated in pilot-scale subsurface flow (SSF) and in free water surface flow (FWS) constructed wetlands installed in the campus of TUBITAK-Marmara Research Center, Gebze, near Istanbul, Turkey. The main purposes of this study are to apply constructed wetlands for the protection of water reservoirs and to reuse wastewater. Experiments were carried out at continuous flow reactors. The effects of the type of plants on the removal were investigated by using emergent (Canna, Cyperus, Typhia spp., Phragmites spp., Juncus, Poaceae, Paspalum and Iris.), submerged (Elodea, Egeria) and floating (Pistia, Salvina and Lemna) marsh plants at different conditions. During the study period HLRs were 30, 50, 70, 80 and 120 L m(2)d(-1) respectively. The average annual NH4-N, NO(3)-N, organic N and TN treatment efficiencies in SSF and FWS wetlands are 81% and 68%, 37% and 49%, 75% and 68%, 47% and 53%, respectively. Nitrification, denitrification and ammonification rate constant (k20) values in SSF and FNS systems have been found as 0.898 d(-1) and 0.541 d(-1), 0.488 d(-1) and 0.502 d(-1), 0.986 d(-1) and 0.908 respectively. Two types of the models (first-order plug flow and multiple regression) were tried to estimate the system performances.

  9. Constructed wetlands as an alternative restoration measure for shallow lakes.

    PubMed

    Bozic, M; Nikolic, G; Rudic, Z; Raicevic, V; Lalevic, B

    2013-01-01

    This paper deals with the consequences of cultural eutrophication and unconventional solutions for shallow lake restoration. Cultural eutrophication is the primary problem that affects especially shallow lakes, due to their physical characteristics (e.g. shallow depth, lack of stratification). Palic Lake, a very shallow Pannonian lake, received treated municipal wastewaters coming from the lagoons of a wastewater treatment plant. The sewage discharge mainly increased the nutrient load to the lake in the last decades. The lake sustainability is affected by inappropriate quality of water that flows into the lake, and abundance of deposited sediment. The technology that can provide both improvement of water quality and resolution of the sediment problem is a constructed wetland, which is designed to utilise the natural processes involving wetland vegetation, soil and their associated microbial assemblages to assist in additional water treatment. The technical solution is based on three key aspects: quality and quantity of deposited sediment, enriched by nutrients; effluent quality; desired lake water quality. A designed constructed wetland can accomplish the desired water quality and gradually remediate deposited sediment.

  10. Constructed Wetlands for Removal of Heavy Metals from NPDES Outfall Effluent

    SciTech Connect

    Nelson, E.A.

    2002-08-29

    The A-01 NPDES outfall at the Savannah River Site receives process wastewater discharges and stormwater runoff from the Savannah River Technology Center. Routine monitoring indicated that copper concentrations were regularly higher than discharge permit limit, necessitating treatment of nearly one million gallons of water each day plus storm runoff to meet compliance standards. A conceptual design for a constructed treatment wetland was developed as the most cost-effective alternative. A pilot study was conducted using mesocosms to confirm that the design concept would reduce copper to acceptable levels. After treatment in the mesocosms, effluent copper concentrations were routinely below permit limits, even though the influent concentrations varied widely.

  11. Integrated Constructed Wetlands (ICW) for livestock wastewater management.

    PubMed

    Harrington, Rory; McInnes, Robert

    2009-11-01

    Social, economic and environmental coherence is sought in the management of livestock wastewater. Wetlands facilitate the biogeochemical processes that exploit livestock wastewater and provide opportunities to achieve such coherence and also to deliver on a range of ecosystem services. The Integrated Constructed Wetland (ICW) concept integrates three inextricably linked objectives: water quantity and quality management, landscape-fit to improve aesthetic site values and enhanced biodiversity. The synergies derived from this explicit integration allow one of the key challenges for livestock management to be addressed. An example utilizing twelve ICW systems from a catchment on the south coast of Ireland demonstrates that over an eight year period mean reduction of total and soluble phosphorus (molybdate reactive phosphorus) exceeded 95% and the mean removal of ammonium-N exceeded 98%. This paper reviews evidence regarding the capacity of ICWs to provide a coherent and sustainable alternative to conventional systems.

  12. Constructed wetlands as sustainable ecotechnologies in decentralization practices: a review.

    PubMed

    Valipour, Alireza; Ahn, Young-Ho

    2016-01-01

    Recently, a range of novel and cost-effective engineered wetland technologies for decentralization practices of domestic wastewater treatment have been developed with ecological process modification, the use of functionalized plants, and advanced biofilm formation. However, selecting the one that can be more appreciated for on-site sanitation is still uncertain. This paper reviews the role of plants, media materials, microorganisms, and oxygen transfer in domestic wastewater purification through constructed wetlands (CWs). The effectiveness of traditional and recently developed CWs and the necessity of an induced biofilm attachment surface (BAS) in these systems for the treatment of domestic sewage are presented. This review also elucidates the idea of CWs for domestic wastewater characteristics highly stressed by total dissolved solids and the adaptive strategies in mitigating the cold climate impacts on their efficiencies. Further research needed to enhance the stability and sustainability of CWs is highlighted. By a more advanced investigation, BAS CWs can be specified as an ideal treatment process in decentralization.

  13. Constructed wetland treatment system for upper blackfoot mining complex

    SciTech Connect

    Sanders, F.S.

    1996-12-31

    A combined passive oxidation/sedimentation (pre-treatment) and constructed wetland (polishing) system has been designed and installed to treat mine drainage at the inactive Upper Blackfoot River Mining Complex northeast of Lincoln, MT. The system is designed to treat up to 100 gpm flow with moderate heavy metal concentrations (25 to 95 mg/L Zn; lower concentrations of Pb, Cu, and As), moderate Fe concentrations (< 100 mg/L), and periodic high acidity (pH 2.6 to 3.5). The treatment scheme is flexible to accommodate a wide range of flows, metal concentrations, and acidity in order to gain cost-efficiencies and to meet restrictive discharge standards for the environmentally-sensitive Blackfoot River watershed. The wetland treatment system presently is undergoing start-up testing and initial tuning and will be operational during summer, 1996. Conceptual and engineering designs are presented along with preliminary data.

  14. Fate of Volatile Organic Compounds in Constructed Wastewater Treatment Wetlands

    USGS Publications Warehouse

    Keefe, S.H.; Barber, L.B.; Runkel, R.L.; Ryan, J.N.

    2004-01-01

    The fate of volatile organic compounds was evaluated in a wastewater-dependent constructed wetland near Phoenix, AZ, using field measurements and solute transport modeling. Numerically based volatilization rates were determined using inverse modeling techniques and hydraulic parameters established by sodium bromide tracer experiments. Theoretical volatilization rates were calculated from the two-film method incorporating physicochemical properties and environmental conditions. Additional analyses were conducted using graphically determined volatilization rates based on field measurements. Transport (with first-order removal) simulations were performed using a range of volatilization rates and were evaluated with respect to field concentrations. The inverse and two-film reactive transport simulations demonstrated excellent agreement with measured concentrations for 1,4-dichlorobenzene, tetrachloroethene, dichloromethane, and trichloromethane and fair agreement for dibromochloromethane, bromo-dichloromethane, and toluene. Wetland removal efficiencies from inlet to outlet ranged from 63% to 87% for target compounds.

  15. Heterotrophic bacterial activities and treatment performance of surface flow constructed wetlands receiving woodwaste leachate.

    PubMed

    Tao, Wendong; Hall, Ken J; Duff, Sheldon J B

    2006-07-01

    Heterotrophic activities were investigated by measuring 3H-leucine incorporation to bacterial protein and 14C-glucose turnover in surface flow constructed wetlands receiving woodwaste leachate. No significant longitudinal variation was found in heterotrophic activities of bacterioplankton. An open wetland, a vegetated wetland, and a fertilized vegetated wetland were used to examine the effects of vegetation and ammonium nitrate amendment. There was not a significant difference in treatment performance among the three wetlands, except for a significant pH increase and more efficient volatile fatty acids removal in the fertilized wetland. The fertilized wetland had the highest leucine incorporation rate and shortest glucose turnover time accompanied by the lowest glucose mineralization percentage, followed by the open wetland, then the vegetated wetland. Planktonic and sedimentary bacteria contributed to the majority of the total heterotrophic activities; epiphytic bacteria played a minor role. Heterotrophic activities were influenced by the availability of nutrient, electron acceptor, and organic substrate.

  16. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater

    USDA-ARS?s Scientific Manuscript database

    Marsh-pond-marsh (M-P-M) constructed wetlands have been used to treat wastewater from swine anaerobic lagoons. To mitigate undesired ammonia emission from M-P-M, ponds were covered with floating wetlands (M-FB-M). The pond sections of the M-FB-M were covered with floating wetlands consisted of recyc...

  17. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater

    USDA-ARS?s Scientific Manuscript database

    Marsh-pond-marsh (M-P-M) constructed wetlands have been used to treat wastewater from swine anaerobic lagoons. To mitigate undesired ammonia emission from M-P-M, ponds were covered with floating wetlands (M-FB-M). The pond sections of the M-FB-M were covered with floating wetlands consisted of recyc...

  18. Domestic wastewater treatment by constructed wetlands enhanced with bioremediating rhizobacteria.

    PubMed

    Salgado, Irina; Cárcamo, Herlen; Carballo, María Elena; Cruz, Mario; Del Carmen Durán, María

    2017-06-23

    Constructed wetlands (CWs) offer several advantages for treating waters; however, the successful application of these systems remains a challenge. Practical solutions to pollution through CWs remain incipient because wetlands are still studied as "black boxes"; further studies are required regarding the involvement of rhizosphere bacteria in the removal of pollutants. This research focused on increasing the performance of CWs treatment systems for the removal of inorganic and organic pollutants from domestic wastewater, by the application of native bioremediating rhizobacteria. A bacterial consortium (CAD/1S) was designed with four rhizobacteria strains isolated from Typha domingensis plants of natural wetlands. Each individual strain was identified by 16S ribosomal RNA (rRNA) gene sequencing. This consortium removed organic matter, ammonium, and phosphate with percentages over 70% from model wastewater. The evaluation of abiotic and biotic factors' influence on pollutant removal indicated the best conditions to remove pollutants: a neutral pH, a 72-h contact time, and an inoculum from single growth of each strain. The subsequent bioaugmentation with the consortium of CWs at laboratory scale allowed 100%, greater than 70 and 55% removal of organic matter, ammonium, and phosphate, respectively. The set of results allowed the proposal of a new strategy for the improvement of CWs technology for the treatment of domestic wastewater pollutants.

  19. Driving forces behind the construction of an eco-compensation mechanism for wetlands in China

    NASA Astrophysics Data System (ADS)

    Wang, Changhai

    2016-09-01

    This research revealed important driving forces behind the construction of an eco-compensation mechanism for wetlands (DFEMW) in China. Using China's provincial panel data from 1978 to 2008, a fixed-effects model was used to analyze the impacts of agricultural production systems on wetlands. We identified three DFEMW as follows: the change of wetland resources and protection measures in China; declaration and implementation of the provincial Wetland Protection Ordinance; and wetland degradation by agricultural production systems, which necessitated the establishment of a wetland eco-compensation mechanism. In addition to the DFEMW, a significant positive correlation between wetland area and both rural population and gross agricultural production was identified, in addition to a negative correlation with chemical fertilizer usage, reservoir storage capacity, and irrigation area. The underlying reasons for the serious degradation and inadequate protection of wetlands were market failure and government failure; these were the driving forces behind the need to establish a wetland eco-compensation mechanism. From a governmental perspective, it has been difficult to rectify market failures in resource distribution and thus to prevent wetland degradation. Factors include conflicts of interest, lack of investment, effective special laws, a simple means to protect wetlands, and a multidisciplinary management system. Therefore, the key factor is the coordination of interest relationships between those who utilize wetlands and those who seek to minimize wetland degradation and effectively protect wetlands.

  20. Mosquito production from four constructed treatment wetlands in peninsular Florida.

    PubMed

    Rey, Jorge R; O'Meara, George F; O'Connell, Sheila M; Cutwa-Francis, Michele M

    2006-06-01

    Several techniques were used to sample adult and immature mosquitoes in 4 constructed treatment wetlands in Florida. Adults of 19 species (7 genera) of mosquitoes were collected, and immatures of the most abundant species and of 60% of all species also were collected. Few significant differences between sites and stations in the numbers of mosquitoes collected were discovered. Culex nigripalpus Theobald was the most abundant mosquito found in adult (carbon dioxide-baited suction traps) and ovitrap collections, whereas Mansonia spp. and Uranotaenia spp. were most common in pump-dip-grab samples. The roles of rooted and floating vegetation and of water quality in determining mosquito production from these areas are discussed.

  1. A review on removing pharmaceutical contaminants from wastewater by constructed wetlands: design, performance and mechanism.

    PubMed

    Li, Yifei; Zhu, Guibing; Ng, Wun Jern; Tan, Soon Keat

    2014-01-15

    This paper presents a comprehensive review of the current state of research activities on the application of constructed wetlands for removing pharmaceutical contaminants from wastewater. The focus of the review was placed on the application of constructed wetlands as an alternative secondary wastewater treatment system or as a wastewater polishing treatment system. The design parameters of the reported constructed wetlands including the physical configuration, hydraulic mode, vegetation species, and targeting pharmaceuticals were summarized. The removal efficiencies of pharmaceuticals under different conditions in the wetlands were evaluated at the macroscopic level. In addition, the importance of the three main components of constructed wetlands (substrate, plants and microbes) for pharmaceutical removal was analyzed to elucidate the possible removal mechanisms involved. There is a general consensus among many researchers that constructed wetlands hold great potential of being used as an alternative secondary wastewater treatment system or as a wastewater polishing treatment system for the removal of pharmaceuticals, but relevant reported studies are scarce and are not conclusive in their findings. Current knowledge is limited on the removal efficiencies of pharmaceuticals in constructed wetlands, the removal mechanisms involved, the toxicity to constructed wetlands caused by pharmaceuticals, and the influences of certain important parameters (configuration design, hydraulic mode, temperature and seasonality, pH, oxygen and redox potential, etc.). This review promotes further research on these issues to provide more and better convincing evidences for the function and performance of larger laboratory-scale, pilot-scale or full-scale constructed wetlands. © 2013.

  2. Integrated Cr(VI) removal using constructed wetlands and composting.

    PubMed

    Sultana, Mar-Yam; Chowdhury, Abu Khayer Md Muktadirul Bari; Michailides, Michail K; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Vayenas, Dimitrios V

    2015-01-08

    The present work was conducted to study integrated chromium removal from aqueous solutions in horizontal subsurface (HSF) constructed wetlands. Two pilot-scale HSF constructed wetlands (CWs) units were built and operated. One unit was planted with common reeds (Phragmites australis) and one was kept unplanted. Influent concentrations of Cr(VI) ranged from 0.5 to 10mg/L. The effect of temperature and hydraulic residence time (8-0.5 days) on Cr(VI) removal were studied. Temperature was proved to affect Cr(VI) removal in both units. In the planted unit maximum Cr(VI) removal efficiencies of 100% were recorded at HRT's of 1 day with Cr(VI) concentrations of 5, 2.5 and 1mg/L, while a significantly lower removal rate was recorded in the unplanted unit. Harvested reed biomass from the CWs was co-composted with olive mill wastes. The final product had excellent physicochemical characteristics (C/N: 14.1-14.7, germination index (GI): 145-157%, Cr: 8-10mg/kg dry mass), fulfills EU requirements and can be used as a fertilizer in organic farming.

  3. Phosphorus removal from trout farm effluents by constructed wetlands.

    PubMed

    Comeau, Y; Brisson, J; Réville, J P; Forget, C; Drizo, A

    2001-01-01

    Freshwater trout farms need a high and continuous clean water flow to keep fish exposed to a non-toxic ammonium concentration. As a result, the concentration of effluents from these farms are even below standard effluent criteria for municipal wastewater effluent for solids, nitrogen and phosphorus. Nevertheless, the mass of pollutants discharged, originating mostly from excreta and undigested fish food, must be reduced by simple and economical treatment processes. We designed and operated a three-stage system aimed at retaining solids by a 60 pm nylon rotating microscreen followed by treatment with a phosphorus-retaining constructed wetland system. Washwater from the microscreen was pumped to a series of two horizontal flow beds of 100 m3 each (0.6 m deep). Coarse (2 mm) and finer (< 2 mm) crushed limestone were used in each bed, respectively, with the first one being planted with reeds (Phragmites australis) and the second one designed to remove even more phosphorus by adsorption and precipitation. Preliminary results indicated that the microscreen captured about 60% of the suspended solids and that greater than 95% of the suspended solids and greater than 80% of the total phosphorus mass loads were retained by the beds. The potential of constructed wetlands as an ecologically attractive and economical method for treating fish farm effluents to reduce solids and phosphorus discharge appears promising.

  4. Efficiency of subsurface flow constructed wetland with trickling filter.

    PubMed

    Vucinic, Aleksandra Anic; Hrenovic, Jasna; Tepes, Predrag

    2012-06-01

    Effective wastewater purification in subsurface flow constructed wetlands must include adequate pretreatment and ensure a sufficient amount of dissolved oxygen. In a pilot-scale operation, a subsurface flow constructed wetland (CW) consisted of a primary settlement tank, a trickling filter for pretreatment and two serially assembled basins. The trickling filter was added to ensure sufficient aeration, increase purification of the wastewater and shorten the wastewater purification time. The estimated nominal flow was 0.7 m3/d. The experiments were conducted using the wastewater from the municipal sewage canal of the city of Zagreb, with utilization of three different flows: 0.72 (A), 1.44 (B) and 2.88 (C) m3/d. The efficiency of the purification process was monitored over a period of three years (TSS, BOD5, COD, NH4-N, NO2-N, PO4-P, dissolved oxygen, temperature and pH). The experimental results showed an increase in the removal efficiency with a doubling of the nominal flow from 0.7 to 1.44 m3/d, which could be related to the implementation of the trickling filter where high removal rates were achieved.

  5. Constructed wetlands design for enhanced phytoremediation of effluents

    SciTech Connect

    Stewart, A.J.; Sparks, B.J.; Carder, J.P.; Sumner, J.R.

    1996-12-31

    The Oak Ridge National Laboratory (ORNL) uses constructed wetlands to solve an environmental compliance problem. Effluents from a coal yard runoff treatment facility (CYRTF) and a sewage treatment plant are both intermittently toxic based on effluent testing conducted under ORNL`s wastewater discharge permit. The CYRTF uses conventional technology (lime neutralization, flocculation); its effluent is toxic due primarily to the presence of high concentrations of calcium. Effluent from the sewage treatment plant is occasionally toxic due to a semivolatile, low-molecular weight constituent, perhaps generated when the wastewater is chlorinated prior to discharge. The two effluent are blended (about 2:8, volume:volume) before being passed through a pair of constructed wetland (CW) cells, each 1.8 m wide and 20 m long, for final equilibration. The CW system treats about 1,800 gallons of blended effluent per day. The effluent blend`s toxicity, as determined by testing with Ceriodaphnia dubia, is reduced by passage through the CW system. This simple aqueous-phase phytoremediation system is environmentally benign and provides the necessary minimal level of treatment for both effluents at low cost. We provide {open_quotes}lessons learned{close_quotes} in building and operating the CW system, and summarize the results of the chemical and toxicological tests used to demonstrate this technology`s application.

  6. Stormwater treatment: do constructed wetlands yield improved pollutant management performance over a detention pond system?

    PubMed

    Bavor, H J; Davies, C M; Sakadevan, K

    2001-01-01

    Constructed wetland systems have been proposed as representing an improved ecotechnological option over detention basins, in terms of their abilities to reduce stormwater bacterial and nutrient loads to receiving waters. Concentrations of microbial and pollutants were determined in inflow and outflow samples collected from each type of system. Removal efficiencies for the wetland although higher than for the pond, were lower than some previously reported values for the treatment of municipal wastewater by constructed wetlands. Performance of a number of constructed wetland systems for stormwater treatment is evaluated considering the functional components of the systems.

  7. Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions.

    PubMed

    Gui, P; Inamori, R; Matsumura, M; Inamori, Y

    2007-01-01

    Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.

  8. Modeling and Understanding BOD Removal Processes in Free-Water Surface Constructed Wetlands

    NASA Astrophysics Data System (ADS)

    Deng, Z.

    2016-12-01

    Free-water surface constructed wetlands have proven to be effective systems for removal of various pollutants in wastewater and agricultural drainage water. Modeling tools are needed for understanding the processes and mechanisms responsible for the removal of pollutants and for the design of new constructed wetlands. This paper presents a new model for mimicking the processes and mechanisms controlling the removal of BOD (biochemical oxygen demand) in free-water surface constructed wetlands. The processes and mechanisms, simulated in the model, include advection, dispersion, diffusion, monod kinetics of bacterial growth, water gains (via precipitation) and losses (evaporation and seepage) and mass exchange between water column and root layers of a wetland. A novel feature of the new model is the incorporation of a dynamic diffusive root-zone. Sensitivity analysis of the model input vaiables indicates that the BOD removal in free water surface constructed wetlands is most sensitive to the biological removal process of BOD in the root zone, controlled by acetic acid and anaerobic bacteria in root zone, and the flow velocity (controlling mean hydraulic residence time) and organic carbon in the water column. The application of the new model is demonstrated through two case studies involving two distinct constructed wetlands with one (Gustine Wetland) for treatment of secondary wastewater located in the USA and another (Lake Manzala Engineered Wetland) for treatment of agricultural drainage water in Egypt. The model is relatively simple yet effective, as evidenced by the high coefficient of determination of 0.73 - 0.99 for the Gustine Wetland and 0.98 for Manzala Wetland. The model is a reliable and efficient tool for designing constructed wetlands and for understanding effects of various processes and mechanisms on the treatment efficiency of wastewater in constructed wetlands.

  9. Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland.

    PubMed

    Moore, M T; Cooper, C M; Smith, S; Cullum, R F; Knight, S S; Locke, M A; Bennett, E R

    2009-01-01

    Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides.

  10. [Segregation effect of purification for nitrogen and phosphate pollution in the subsurface flow constructed wetlands].

    PubMed

    Liu, Shu-Yuan; Yan, Bai-Xing; Wang, Li-Xia

    2011-03-01

    Three minitype subsurface-horizontal flow constructed wetlands planted with Calamagrostis angustifolia and Phragmites australis and filled with soil and slag were used to investigate the N, P and pH for upper layer and underlayer wetland system by intermission operation. Results demonstrated that TN removal rates in the superstratum of Calamagrostis angustifolia and Phragmites australis wetlands were 0.771 g x (m2 x d)(-1), 1.481 g x(m2 x d)(-1) with 10 days of the hydraulic retention, which were 1.15 and 1.31 times higher than that of underlayer wetland systems, respectively. Simultaneity, TP removal rates in the superstratum of Calamagrostis angustifolia and Phragmites australis wetlands were 1.655 g x (m2 x d)(-1), 6.838 g x (m2 x d)(-1), respectively, which were 1.13 and 1.28 times higher than that of underlayer wetland systems, respectively. The purification ability of upper layer in the wetland system was higher than that of underlayer. A regular trend of pH changes and upstanding buffer ability of wetland system were found. The pH values in the upper layer of soil-slag wetlands were smaller than that of underlayer which was contrary to the soil wetland. The break-point of pH curve indicates the termination of NH4(+) -N reaction in constructed wetland.

  11. Removal and factors influencing removal of sulfonamides and trimethoprim from domestic sewage in constructed wetlands.

    PubMed

    Dan A; Yang, Yang; Dai, Yu-nv; Chen, Chun-xing; Wang, Su-yu; Tao, Ran

    2013-10-01

    Twelve pilot-scale constructed wetlands with different configurations were set up in the field to evaluate the removal and factors that influence removal of sulfonamides (sulfadiazine, sulfapyridine, sulfacetamide, sulfamethazine and sulfamethoxazole) and trimethoprim from domestic sewage. The treatments included four flow types, three substrates, two plants and three hydraulic loading rates across two seasons (summer and winter). Most target antibiotics were efficiently removed by specific constructed wetlands; in particular, all types of constructed wetlands performed well for the degradation of sulfapyridine. Flow types were the most important influencing factor in this study, and the best removal of sulfonamides was achieved in vertical subsurface-flow constructed wetlands; however, the opposite phenomenon was found with trimethoprim. Significant relationships were observed between antibiotic degradation and higher temperature and redox potential, which indicated that microbiological pathways were the most probable degradation route for sulfonamides and trimethoprim in constructed wetlands. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Constructed Wetlands for Treatment of Organic and Engineered Nanomaterial Contaminants of Emerging Concerns (WaterRF Report 4334)

    EPA Science Inventory

    The goal of this project was to determine hydraulic and carbon loading rates for constructed wetlands required for achieving different levels of organic and nanomaterial contaminants of emerging concern (CECs) removal in constructed wetlands. Specific research objectives included...

  13. Constructed Wetlands for Treatment of Organic and Engineered Nanomaterial Contaminants of Emerging Concerns (WaterRF Report 4334)

    EPA Science Inventory

    The goal of this project was to determine hydraulic and carbon loading rates for constructed wetlands required for achieving different levels of organic and nanomaterial contaminants of emerging concern (CECs) removal in constructed wetlands. Specific research objectives included...

  14. [Optimization of aerobic/anaerobic subsurface flow constructed wetlands].

    PubMed

    Li, Feng-Min; Shan, Shi; Li, Yuan-Yuan; Li, Yang; Wang, Zheng-Yu

    2012-02-01

    Previous studies showed that setting aerobic and anaerobic paragraph segments in the subsurface constructed wetlands (SFCWs) can improve the COD, NH4(+)-N, and TN removal rate, whereas the oxygen enrichment environment which produced by the artificial aeration could restrain the NO3(-)-N and NO2(-)-N removal process, and to a certain extent, inhibit the denitrification in SFCWs Therefore, in this research the structure and technology of SFCW with aerobic and anaerobic paragraph segments were optimized, by using the multi-point water inflow and setting the corresponding section for the extra pollutant removal. Results showed that with the hydraulic load of 0.06 m3 x (m2 x d)(-1), the COD, NH4(+)-N and TN removal efficiencies in the optimized SFCW achieved 91.6%, 100% and 87.7% respectively. COD/N increased to 10 speedily after the inflow supplement. The multi-point water inflow could add carbon sources, and simultaneously maximum utilization of wetland to remove pollutants. The optimized SFCW could achieve the purposes of purification process optimization, and provide theoretical basis and application foundation for improving the total nitrogen removal efficiency.

  15. Seafood wastewater treatment in constructed wetland: tropical case.

    PubMed

    Sohsalam, Prapa; Englande, Andrew Joseph; Sirianuntapiboon, Suntud

    2008-03-01

    A series of investigations were conducted to evaluate the feasibility of using constructed wetlands to remove pollutants from seafood processing wastewater. Six emergent plant species; Cyperus involucratus, Canna siamensis, Heliconia spp., Hymenocallis littoralis, Typha augustifolia and Thalia deabata J. Fraser were planted in surface flow wetland. They were fed with seafood wastewater that was 50% diluted with treated seafood wastewater from an aerated lagoon. All macrophytes were found to meet satisfying treatment efficiency (standard criteria for discharged wastewater) at 5 days hydraulic retention time (HRT). While C. involucratus, T. deabata and T. augustifolia met acceptable treatment efficacy at 3 days HRT. Nutrient uptake rate of these species was observed in the range of 1.43-2.30 g Nitrogen/m(2)day and 0.17-0.29 g Phosphorus/m(2)day, respectively at 3 days HRT. The highest treatment performances were found at 5 days HRT. Average removal efficiencies were 91-99% for BOD(5), 52-90% for SS, 72-92% for TN and 72-77% for TP. Plant growth and nitrogen assimilation were experienced to be most satisfactory for C. involucratus, T. deabata and T. augustifolia. Lower HRTs affected contaminant removal efficiency for all species. C. involucratus, T. deabata and T. augustifolia can remove all contaminants efficiently even at the lowest hydraulic retention time (1 day).

  16. Specifically Designed Constructed Wetlands: A Novel Treatment Approach for Scrubber Wastewater

    SciTech Connect

    John H. Rodgers Jr; James W. Castle; Chris Arrington: Derek Eggert; Meg Iannacone

    2005-09-01

    A pilot-scale wetland treatment system was specifically designed and constructed at Clemson University to evaluate removal of mercury, selenium, and other constituents from flue gas desulfurization (FGD) wastewater. Specific objectives of this research were: (1) to measure performance of a pilot-scale constructed wetland treatment system in terms of decreases in targeted constituents (Hg, Se and As) in the FGD wastewater from inflow to outflow; (2) to determine how the observed performance is achieved (both reactions and rates); and (3) to measure performance in terms of decreased bioavailability of these elements (i.e. toxicity of sediments in constructed wetlands and toxicity of outflow waters from the treatment system). Performance of the pilot-scale constructed wetland treatment systems was assessed using two criteria: anticipated NPDES permit levels and toxicity evaluations using two sentinel toxicity-testing organisms (Ceriodaphnia dubia and Pimephales promelas). These systems performed efficiently with varied inflow simulations of FGD wastewaters removing As, Hg, and Se concentrations below NPDES permit levels and reducing the toxicity of simulated FGD wastewater after treatment with the constructed wetland treatment systems. Sequential extraction procedures indicated that these elements (As, Hg, and Se) were bound to residual phases within sediments of these systems, which should limit their bioavailability to aquatic biota. Sediments collected from constructed wetland treatment systems were tested to observe toxicity to Hyalella azteca or Chironomus tetans. Complete survival (100%) was observed for H. azteca in all cells of the constructed wetland treatment system and C. tentans had an average of 91% survival over the three treatment cells containing sediments. Survival and growth of H. azteca and C. tentans did not differ significantly between sediments from the constructed wetland treatment system and controls. Since the sediments of the constructed

  17. Efficiencies of freshwater and estuarine constructed wetlands for phenolic endocrine disruptor removal in Taiwan.

    PubMed

    Hsieh, Chi-Ying; Yang, Lei; Kuo, Wen-Chien; Zen, Yi-Peng

    2013-10-01

    We examined the distribution and removal efficiencies of phenolic endocrine disruptors (EDs), namely nonylphenol diethoxylates (NP2EO), nonylphenol monoethoxylates (NP1EO), nonylphenol (NP), and octylphenol (OP), in wastewater treated by estuarine and freshwater constructed wetland systems in Dapeng Bay National Scenic Area (DBNSA) and along the Dahan River in Taiwan. Water samples were taken bimonthly at 30 sites in three estuarine constructed wetlands (Datan, Pengcun and Linbian right bank (A and B)) in DBNSA, for eight sampling campaigns. The average removal efficiencies were in the range of 3.13-97.3% for wetlands in DBNSA. The highest average removal occurred in the east inlet to the outlet of the Tatan wetland. The most frequently detected compound was OP (57.7%), whose concentration was up to 1458.7 ng/L in DBNSA. NP was seen in only 20.5% of the samples. The temporal variation of EDs showed a decrease across seasons, where summer>spring>winter>autumn in these constructed wetlands. The removal efficiencies of EDs by estuarine wetlands, in decreasing order, were Datan>Pengcun>Linbian right bank in DBNSA. Water samples collected at 18 sites in three freshwater constructed wetlands (Daniaopi, Hsin-Hai I, and Hsin-Hai II) along the riparian area of Dahan River. NP2EO was the most abundant compound, with a concentration of up to 11,200 ng/L. Removal efficiencies ranged from 55% to 91% for NP1EO, NP2EO, and NP in Hsin-Hai I. The average removal potential of EDs in freshwater constructed wetlands, in decreasing order, was Hsin-Hai II>Daniaopi>Hsin-Hai I constructed wetlands. The lowest concentrations of the selected compounds were observed in the winter. The highest removal efficiency of the selected phenolic endocrine disruptors was achieved by Hsin-Hai I wetland. The calculated risk quotients used to evaluate the ecological risk were up to 30 times higher in the freshwater wetlands along Dahan River than in the estuarine (DBNSA) constructed wetlands, indicating

  18. Atrazine degradation by bioaugmented sediment from constructed wetlands.

    PubMed

    Runes, H B; Jenkins, J J; Bottomley, P J

    2001-10-01

    The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.

  19. Use of vetiver grass constructed wetland for treatment of leachate.

    PubMed

    Bwire, K M; Njau, K N; Minja, R J A

    2011-01-01

    Performance of Constructed Wetland planted with vetiver grasses for the treatment of leachate was investigated in controlled experiments involving horizontal subsurface flow constructed wetland (HSSFCW). The HSSFCW experimental unit had two cells, one planted with vetiver grasses and another bare. Both units were packed with limestone gravel as substrate and were operated with equal hydraulic loading and hydraulic retention time. Collected samples of influents and effluents were analysed for COD, Cr, Pb, Fe and pH. The results showed that vetiver grasses tolerated leachate with high loading of COD up to 14,000 mg L(-1). The planted cell outperformed the unplanted cell in terms of COD, Cr, Pb and Fe removal. The systems showed optimum points for COD and Pb removal as a function of feed concentrations. The optimum COD removal values of 210 mgm(-2) day(-1) at feed COD concentration of 11,200 mg COD L(-1) and 89 mgm(-2) day(-1) at feed concentration of 7,200 mg COD L(-1) were obtained for planted and unplanted cells respectively. Similarly Pb removal values of 0.0132 mgm(-2) day(-1) at 1.0 mg Pb L(-1) and 0.0052 mgm(-2) day(-1) at 1.04 mgPb L(-1) were obtained for planted and unplanted units respectively. Removal of Fe as a function of feed Fe concentration showed a parabolic behaviour but Cr removal showed linear behaviour with feed Cr concentrations in both units. The system showed very good removal efficiencies with Cr and Fe but poor efficiencies were recorded for Pb.

  20. The universal design, operation and maintenance guidelines for farm constructed wetlands (FCW) in temperate climates.

    PubMed

    Carty, Aila; Scholz, Miklas; Heal, Kate; Gouriveau, Fabrice; Mustafa, Atif

    2008-10-01

    This paper comprises the scientific justification for the Farm Constructed Wetland (FCW) Design Manual for Northern Ireland and Scotland. Moreover, this document addresses an international audience interested in applying wetland systems in the wider agricultural context. Farm constructed wetlands combine farm wastewater (predominantly farmyard runoff) treatment with landscape and biodiversity enhancements, and are a specific application and class of integrated constructed wetlands (ICW), which have wider applications in the treatment of other wastewater types such as domestic sewage. The aim of this review paper is to propose guidelines highlighting the rationale for FCW, including key water quality management and regulatory issues, important physical and biochemical wetland treatment processes, assessment techniques for characterizing potential FCW sites and discharge options to water bodies. The paper discusses universal design, construction, planting, maintenance and operation issues relevant specifically for FCW in a temperate climate, but highlights also catchment-specific requirements to protect the environment.

  1. Performance of a subsurface-flow constructed wetland in southern China.

    PubMed

    Shi, Lei; Wang, Bao-zhen; Cao, Xiang-dong; Wang, Jin; Lei, Zhi-hong; Wang, Zhi-ren; Liu, Zheng-ying; Lu, Bing-nan

    2004-01-01

    The operational performance of a full-scale subsurface-flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD5/COD mean ratio of 0.33 at Shatian, Shenzhen City was studied. The constructed wetland system consists of screens, sump, pumping station, and primary settling basin, facultative pond, first stage wetland and secondary stage wetland. The designed treatment capacity is 5000 m3/d, and the actual influent flow is in the range of < 2000 to > 10000 m3/d. Under normal operational conditions, the final effluent quality well met the National Integrated Wastewater Discharge Standard (GB 8978-1996), with the following parameters(mean values): COD 33.90 mg/L, BOD, 7.65 mg/L, TSS 7.92 mg/L, TN 9.11 mg/L and TP 0.56 mg/L. Seven species of plants were selected to grow in the wetland: Reed, Sweetcane flower Silvergrass, Great Bulrush, Powdery Thalia and Canna of three colours. The growing season is a whole year-round. The seasonal discrepancy could be observed and the plants growing in the wetland are vulnerable to lower temperature in winter. The recycling of the effluent in the first stage of the wetland system is an effective measure to improve the performance of the wetland system. The insufficient DO value in the wetland system not only had significant effect on pollutants removal in the wetland, but also was unfavourable to plant growth. The recycling of effluent to the inlet of wetland system and artificial pond to increase DO value of influent to the wetland is key to operate the subsurface constructed wetland steadily and effectively.

  2. Greenhouse gas emissions from surface flow and subsurface flow constructed wetlands treating dairy wastewater.

    PubMed

    VanderZaag, A C; Gordon, R J; Burton, D L; Jamieson, R C; Stratton, G W

    2010-01-01

    Agricultural wastewater treatment is important for protecting water quality in rural ecosystems, and constructed wetlands are an effective treatment option. During treatment, however, some C and N are converted to CH(4), N(2)O, respectively, which are potent greenhouse gases (GHGs). The objective of this study was to assess CH(4), N(2)O, and CO(2) emissions from surface flow (SF) and subsurface flow (SSF) constructed wetlands. Six constructed wetlands (three SF and three SSF; 6.6 m(2) each) were loaded with dairy wastewater in Truro, Nova Scotia, Canada. From August 2005 through September 2006, GHG fluxes were measured continuously using transparent steady-state chambers that encompassed the entire wetlands. Flux densities of all gases were significantly (p < 0.01) different between SF and SSF wetlands changed significantly with time. Overall, SF wetlands had significantly (p < 0.01) higher emissions of CH(4) N(2)O than SSF wetlands and therefore had 180% higher total GHG emissions. The ratio of N(2)O to CH(4) emissions (CO(2)-equivalent) was nearly 1:1 in both wetland types. Emissions of CH(4)-C as a percentage of C removal varied seasonally from 0.2 to 27% were 2 to 3x higher in SF than SSF wetlands. The ratio of N(2)O-N emitted to N removed was between 0.1 and 1.6%, and the difference between wetland types was inconsistent. Thus, N(2)O emissions had a similar contribution to N removal in both wetland types, but SSF wetlands emitted less CH(4) while removing more C from the wastewater than SF wetlands.

  3. Wastewater treatment performance efficiency of constructed wetlands in African countries: a review.

    PubMed

    Mekonnen, Andualem; Leta, Seyoum; Njau, Karoli Nicholas

    2015-01-01

    In Africa, different studies have been conducted at different scales to evaluate wastewater treatment efficiency of constructed wetland. This paper aims to review the treatment performance efficiency of constructed wetland used in African countries. In the reviewed papers, the operational parameters, size and type of wetland used and the treatment efficiency are assessed. The results are organized and presented in six tables based on the type of wetland and wastewater used in the study. The results of the review papers indicated that most of the studies were conducted in Tanzania, Egypt and Kenya. In Kenya and Tanzania, different full-scale wetlands are widely used in treating wastewater. Among wetland type, horizontal subsurface flow wetlands were widely studied followed by surface flow and hybrid wetlands. Most of the reported hybrid wetlands were in Kenya. The results of the review papers indicated that wetlands are efficient in removing organic matter (biochemical oxygen demand and chemical oxygen demand) and suspended solids. On the other hand, nutrient removal efficiency appeared to be low.

  4. Phytoremediation of explosives contaminated groundwater in constructed wetlands: 2. Flow through study. Draft report

    SciTech Connect

    DBehrends, L.L.; Sikora, F.J.; Phillips, W.D.; Baily, E.; McDonald, C.

    1996-02-01

    This study evaluates the utility of constructed wetlands for remediating explosives contaminated groundwaters using bench scale flow-through type reactors. Specifially the study examines: the degradation of TNT, TNB, RDX, and HMX in contaminated waters in plant lagoons and gravel-based wetlands. The study also provides design recommendations for the wetland demonstration project to be located at the Milan Army Ammunition Plant (MAAP), in Tennessee.

  5. [Limestone and pyrite-limestone constructed wetlands for treating river water].

    PubMed

    Zhang, Jing; Li, Rui-hua; Li, Jie; Hu, Jun-song; Sun, Qian-qian

    2013-09-01

    Polluted river water was treated with limestone and pyrite-limestone subsurface horizontal constructed wetlands. The aims were to know the performance of two wetlands on removal of common pollutants, especially nitrogen and phosphorus, and analyze the actions of these minerals. The relationship between hydraulic retention time and purification performance of two constructed wetlands was studied. The optimal hydraulic retention time for pollutant removal was about 3 d, The average removal efficiency of COD, TN and TP were 51%, 70% and 95%, respectively. With same influent and hydraulic loading, the average removal efficiency of COD, NH4+ -N, TN and TP were 53.93%, 82.13%, 66%, 50.9%, and 51.66%, 77.43%, 72.06%, 97.35% for limestone and pyrite-limestone constructed wetlands, respectively. There were few differences between limestone and pyrite-limestone wetlands on COD removal, but the nitrogen and phosphorus removal of pyrite-limestone constructed wetland was higher than that of limestone constructed wetland. The phosphorus removal of pyrite-limestone wetland was more efficiency and stable, not affected by temperature.

  6. Using stable isotopes of water and strontium to investigate the hydrology of a natural and a constructed wetland

    USGS Publications Warehouse

    Hunt, R.J.; Bullen, T.D.; Krabbenhoft, D.P.; Kendall, C.

    1998-01-01

    Wetlands cannot exist without water, but wetland hydrology is difficult to characterize. As a result, compensatory wetland mitigation often only assumes the proper hydrology has been created. In this study, water sources and mass transfer processes in a natural and constructed wetland complex were investigated using isotopes of water and strontium. Water isotope profiles in the saturated zone revealed that the natural wetland and one site in the constructed wetland were primarily fed by ground water; profiles in another constructed wetland site showed recent rain was the predominant source of water in the root zone. Water isotopes in the capillary fringe indicated that the residence time for rain is less in the natural wetland than in the constructed wetland, thus transpiration (an important water sink) was greater in the natural wetland. Strontium isotopes showed a systematic difference between the natural and constructed wetlands that we attribute to the presence or absence of peat. In the peat-rich natural wetland, ??87Sr in the pore water increased along the flowline due to preferential weathering of minerals containing radiogenic Sr in response to elevated Fe concentrations in the water. In the constructed wetland, where peat thickness was thin and Fe concentrations in water were negligible, ??87Sr did not increase along the flowline. The source of the peat (on-site or off-site derived) applied in the constructed wetland controlled the ??87Sr at the top of the profile, but the effects were restricted by strong cation exchange in the underlying fluvial sediments. Based on the results of this study, neither constructed wetland site duplicated the water source and weathering environment of the adjoining natural wetland. Moreover, stable isotopes were shown to be effective tools for investigating wetlands and gaining insight not easily obtained using non-isotopic techniques. These tools have potential widespread application to wetlands that have distinct isotopic

  7. Establishment of a constructed wetland in extreme dryland.

    PubMed

    Tencer, Yoram; Idan, Gil; Strom, Marjorie; Nusinow, Uri; Banet, Dorit; Cohen, Eli; Schröder, Peter; Shelef, Oren; Rachmilevitch, Shimon; Soares, Ines; Gross, Amit; Golan-Goldhirsh, Avi

    2009-11-01

    The project was set to construct an extensive wetland in the southernmost region of Israel at Kibbutz Neot Smadar (30 degree 02'45" N and 35 degree 01'19" E). The results of the first period of monitoring, summary, and perspectives are presented. The constructed wetland (CW) was built and the subsequent monitoring performed in the framework of the Southern Arava Sustainable Waste Management Plan, funded by the EU LIFE Fund. The specific aims were: (1) To end current sewage disposal and pollution of the ground, the aquifer, and the dry river bed (wadi) paths by biologically treating the sewage as part of the creation of a sustainable wetland ecosystem. (2) Serve as an example of CW in the Negev highlands and the Arava Valley climates for neighboring communities and as a test ground for plants and building methods appropriate to hyper arid climate. (3) Serve as an educational resource and tourist attraction for groups to learn about water reuse, recycling, local wildlife and migrating birds, including serving the heart of a planned Ecological-Educational Bird Park. This report is intended to allow others who are planning similar systems in hyper arid climates to learn from our experience. The project is located in an extreme arid desert with less than 40 mm of rain annually and temperature ranges of -5 degree C to +42 degree C. The site receives 165-185 m3 of municipal and agricultural wastes daily, including cowshed and goat wastes and winery outflow. The CW establishment at Neot Smadar was completed in October 2006. For 8 months, clean water flowed through the system while the plants were taking root. In June 2007, the wetland was connected to the oxidation pond and full operation began. Because of seepage and evaporation, during the first several months, the water level was not high enough to allow free flow from one bed to the next. To bed A, the water was pumped periodically from the oxidation pond (Fig. 1) and from there flowed by gravitation through the rest

  8. The removal of pathogens in surface-flow constructed wetlands and its implications for water reuse.

    PubMed

    Ghermandi, A; Bixio, D; Traverso, P; Cersosimo, I; Thoeye, C

    2007-01-01

    Microbiological quality represents the biggest concern to the reuse of treated wastewater. This paper reports and discusses the results of an international survey on the removal of indicators of microbiological contamination in surface-flow constructed wetlands. Constructed wetlands consistently provide a reduction of 90-99% (1-2 log-removal) in the concentration of indicators such as coliform bacteria and faecal streptococci. This removal is found in wetlands treating water from different types of pretreatment (primary sedimentation, activated sludge, trickling filter, maturation ponds). On the other hand, when the influent is of high microbiological quality, wetlands act as sources of pathogenic contamination. The final water quality, however, is still compatible with medium to no-contact recreational activities and other final water uses. High variability in the effluent quality and seasonality might limit the opportunities for reuse. The role of constructed wetlands in different treatment schemes and the remaining open questions concerning removal mechanisms and reference pathogens are discussed.

  9. Changes in the Vegetation Cover in a Constructed Wetland at Argonne National Laboratory, Illinois

    SciTech Connect

    Bergman, C.L.; LaGory, K.

    2004-01-01

    Wetlands are valuable resources that are disappearing at an alarming rate. Land development has resulted in the destruction of wetlands for approximately 200 years. To combat this destruction, the federal government passed legislation that requires no net loss of wetlands. The United States Army Corps of Engineers (USACE) is responsible for regulating wetland disturbances. In 1991, the USACE determined that the construction of the Advanced Photon Source at Argonne National Laboratory would damage three wetlands that had a total area of one acre. Argonne was required to create a wetland of equal acreage to replace the damaged wetlands. For the first five years after this wetland was created (1992-1996), the frequency of plant species, relative cover, and water depth was closely monitored. The wetland was not monitored again until 2002. In 2003, the vegetation cover data were again collected with a similar methodology to previous years. The plant species were sampled using quadrats at randomly selected locations along transects throughout the wetland. The fifty sampling locations were monitored once in June and percent cover of each of the plant species was determined for each plot. Furthermore, the extent of standing water in the wetland was measured. In 2003, 21 species of plants were found and identified. Eleven species dominated the wetland, among which were reed canary grass (Phalaris arundinacea), crown vetch (Coronilla varia), and Canada thistle (Cirsium arvense). These species are all non-native, invasive species. In the previous year, 30 species were found in the same wetland. The common species varied from the 2002 study but still had these non-native species in common. Reed canary grass and Canada thistle both increased by more than 100% from 2002. Unfortunately, the non-native species may be contributing to the loss of biodiversity in the wetland. In the future, control measures should be taken to ensure the establishment of more desired native species.

  10. Wineries wastewater treatment by constructed wetlands: a review.

    PubMed

    Masi, F; Rochereau, J; Troesch, S; Ruiz, I; Soto, M

    2015-01-01

    The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies demonstrated the efficiency of constructed wetlands (CWs) as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal subsurface flow and vertical subsurface flow classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems. This paper is presenting an overview of all the reported experiences at worldwide level during the last 15 years, giving particular attention and provision of details to those systems that have proven to get reliable and constant performances in the long-term period and that have been designed and realized as optimized solutions for the application of CW technology to this particular kind of wastewater. The organic loading rates (OLRs) applied to the examined 13 CW systems ranged from about 30 up to about 5,000 gCOD/m² d (COD: chemical oxygen demand), with the 80th percentile of the reported values being below 297 gCOD/m² d and the median at 164 gCOD/m² d; the highest OLR values have in all cases been measured during the peak season (vintage) and often have been linked to lower surface removal rates (SRRs) in comparison to the other periods of the year. With such OLRs the SRRs have ranged from a minimum of 15 up to 4,700 gCOD/m² d, with the 80th percentile of the reported values being below 308 gCOD/m² d and the median at 112 gCOD/m² d.

  11. Removal mechanisms and fate of insecticides in constructed wetlands.

    PubMed

    Budd, Robert; O'geen, Anthony; Goh, Kean S; Bondarenko, Svetlana; Gan, Jay

    2011-06-01

    Constructed wetlands (CWs), along with other vegetative systems, are increasingly being promoted as a mitigation practice to treat non-point source runoff to reduce contaminants such as pesticides. However, studies so far have mostly focused on demonstrating contaminant removal efficiency. In this study, using two operational CWs located in the Central Valley of California, we explored the mechanisms underlying the removal of pyrethroids and chlorpyrifos from agricultural runoff water, and further evaluated the likelihood for the retained pesticides to accumulate within the CWs over time. In the runoff water passing through the CWs, pyrethroids were associated overwhelmingly with suspended solids >0.7 μm, and the sorbed fraction accounted for 38-100% of the total concentrations. The derived K(d) values for the suspended solids were in the order of 10(4)-10(5), substantially greater than those reported for bulk soils and sediments. Distribution of pyrethroids in the wetland sediments was found to mimic organic carbon distribution, and was enriched in large particles that were partially decomposed plant materials, and clay-size particles (<2 μm). Retention of suspended particles, especially the very large particles (>250 μm) and the very fine particles, is thus essential in removing pyrethroids and chlorpyrifos in CWs. Under flooded and anaerobic conditions, most pyrethroids and chlorpyrifos showed moderate persistence, with DT(50) values between 106-353 d. However, the retained pyrethroids were very stable in dry and aerobic sediments between irrigation seasons, suggesting a possibility for accumulation over time. Therefore, the long-term ecological risks of CWs should be further understood before their wide adoption.

  12. Morphological response of Typha domingensis to an industrial effluent containing heavy metals in a constructed wetland.

    PubMed

    Hadad, H R; Mufarrege, M M; Pinciroli, M; Di Luca, G A; Maine, M A

    2010-04-01

    Typha domingensis had become the dominant species after 2 years of operation of a wetland constructed for metallurgical effluent treatment. Therefore, the main purpose of this study was to investigate its ability to tolerate the effluent and to maintain the contaminant removal efficiency of the constructed wetland. Plant, sediment, and water at the inlet and outlet of the constructed wetland and in two natural wetlands were sampled. Metal concentration (Cr, Ni, and Zn) and total phosphorus were significantly higher in tissues of plants growing at the inlet in comparison with those from the outlet and natural wetlands. Even though the chlorophyll concentration was sensitive to effluent toxicity, biomass and plant height at the inlet and outlet were significantly higher than those in the natural wetlands. The highest root and stele cross-sectional areas, number of vessels, and biomass registered in inlet plants promoted the uptake, transport, and accumulation of contaminants in tissues. The modifications recorded accounted for the adaptability of T. domingensis to the conditions prevailing in the constructed wetland, which allowed this plant to become the dominant species and enabled the wetland to maintain a high contaminant retention capacity.

  13. Designing a constructed wetland for the detention of agricultural runoff for water quality improvement.

    PubMed

    Millhollon, Eddie P; Rodrigue, Paul B; Rabb, James L; Martin, Danny F; Anderson, Russell A; Dans, Darinda R

    2009-01-01

    The goal of this study was to construct a wetland that would detain runoff from a 162-ha watershed for the purposes of improving water quality. The volume of runoff that needed to be detained was determined to be that amount coming off the 162-ha watershed consisting of 146 ha of cultivated crop land and 16 ha of pasture that exceeded the amount that would have come off of the watershed in its natural, forested state. The Soil Conservation Service (now the Natural Resource Conservation Service [NRCS]) runoff curve number method was used to estimate runoff from the watershed in its natural, forested state and in its current state of cultivated crop land and pasture. The design of the constructed wetland was accomplished using the natural topography of the wetland site and the design criteria for a sediment containment system developed by NRCS. The SPAW (Soil-Plant-Atmosphere-Water Field & Pond Hydrology) computer model was used to model depth and volume in the wetland to determine if the constructed wetland design would accommodate typical runoff events. Construction of the wetland occurred over a 4-mo period. The capabilities of the system were verified when Hurricane Rita deposited above-normal rainfall to the wetland site area. The wetland was able to accommodate this event, allowing flow through the system for 9 d, followed by continued detention of remaining runoff for water quality improvement.

  14. Carbon sequestration in surface flow constructed wetland after 12 years of swine wastewater treatment

    USDA-ARS?s Scientific Manuscript database

    Constructed wetlands used for the treatment of swine wastewater may potentially sequester significant amounts of carbon. In past studies, we evaluated the treatment efficiency of wastewater in marsh-pond-marsh design wetland system. The functionality of this system was highly dependent on soil carbo...

  15. PREDICTING SUSTAINABLE GROUND WATER TO CONSTRUCTED RIPARIAN WETLANDS: SHAKER TRACE, OHIO, USA

    EPA Science Inventory

    Water isotopy is introduced as a best management practice for the prediction of sustained ground water inflows to prospective constructed wetlands. A primer and application of the stable isotopes, 18O and 2H, are discussed for riparian wetland restoration ar...

  16. Regulatory Implications of Using Constructed Wetlands to Treat Selenium-Laden Wastewater

    Treesearch

    A. Dennis Lemly; Harry M. Ohlendorf

    2002-01-01

    The practice of using constructed wetlands to treat selenium-laden wastewater is gaining popularity in the linited States and elsewhere. However, proponents of treatment wetlands often overlook important ecological liabilities and regulatory implications when developing new methods and applications. Their research studies typically seek to answer a basic performance...

  17. PREDICTING SUSTAINABLE GROUND WATER TO CONSTRUCTED RIPARIAN WETLANDS: SHAKER TRACE, OHIO, USA

    EPA Science Inventory

    Water isotopy is introduced as a best management practice for the prediction of sustained ground water inflows to prospective constructed wetlands. A primer and application of the stable isotopes, 18O and 2H, are discussed for riparian wetland restoration ar...

  18. The hydrological functioning of a constructed fen wetland watershed.

    PubMed

    Ketcheson, Scott J; Price, Jonathan S; Sutton, Owen; Sutherland, George; Kessel, Eric; Petrone, Richard M

    2017-12-15

    Mine reclamation requires the reconstruction of entire landforms and drainage systems. The hydrological regime of reclaimed landscapes will be a manifestation of the processes operating within the individual landforms that comprise it. Hydrology is the most important process regulating wetland function and development, via strong controls on chemical and biotic processes. Accordingly, this research addresses the growing and immediate need to understand the hydrological processes that operate within reconstructed landscapes following resource extraction. In this study, the function of a constructed fen watershed (the Nikanotee Fen watershed) is evaluated for the first two years following construction (2013-2014) and is assessed and discussed within the context of the construction-level design. The system design was capable of sustaining wet conditions within the Nikanotee Fen during the snow-free period in 2013 and 2014, with persistent ponded water in some areas. Evapotranspiration dominated the water fluxes from the system. These losses were partially offset by groundwater discharge from the upland aquifer, which demonstrated strong hydrologic connectivity with the fen in spite of most construction materials having lower than targeted saturated hydraulic conductivities. However, the variable surface infiltration rates and thick placement of a soil-capping layer constrained recharge to the upland aquifer, which remained below designed water contents in much of the upland. These findings indicate that it is possible to engineer the landscape to accommodate the hydrological functions of a fen peatland following surface oil sands extraction. Future research priorities should include understanding the storage and release of water within coarse-grained reclaimed landforms as well as evaluating the relative importance of external water sources and internal water conservation mechanisms for the viability of fen ecosystems over the longer-term. Copyright © 2017 Elsevier B

  19. Using stable isotopes of water and strontium to investigate the hydrology of a natural and a constructed wetland

    SciTech Connect

    Hunt, R.J.; Krabbenhoft, D.P.; Bullen, T.D.; Kendall, C.

    1998-05-01

    Wetlands cannot exist without water, but wetland hydrology is difficult to characterize. In this study, water sources and mass transfer processes in a natural and constructed wetland complex were investigated using isotopes of water and strontium. Water isotope profiles in the saturated zone revealed that the natural wetland and one site in the constructed wetland were primarily fed by ground water; profiles in another constructed wetland site showed recent rain was the predominant source of water in the root zone. Water isotopes in the capillary fringe indicated that the residence time for rain is less in the natural wetland than in the constructed wetland, thus transpiration (an important water sink) was greater in the natural wetland. Strontium isotopes showed a systematic difference between the natural and constructed wetlands that the authors attribute to the presence or absence of peat. In the peat-rich natural wetland, {delta}{sup 87}Sr in the pore water increased along the flowline due to preferential weathering of minerals containing radiogenic Sr in response to elevated Fe concentrations in the water. In the constructed wetland, where peak thickness was thin and Fe concentrations in water were negligible, {delta}{sup 87}Sr did not increase along the flowline. The source of the pea (on-site or off-site derived) applied in the constructed wetland controlled the {delta}{sup 87}Sr at the top of the profile, but the effects were restricted by strong cation exchange in the underlying fluvial sediments. Based on the results of this study, neither constructed wetland site duplicated the water source and weathering environment of the adjoining natural wetland. Moreover, stable isotopes were shown to be effective tools for investigating wetlands and gaining insight not easily obtained using non-isotopic techniques. These tools have potential widespread application to wetlands that have distinct isotopic endmember sources.

  20. Field test results for nitrogen removal by the constructed wetland component of an agricultural water recycling system

    USDA-ARS?s Scientific Manuscript database

    Wetland Reservoir Subirrigation Systems (WRSIS) are innovative agricultural water recycling systems that can provide economic and environmental benefits. A constructed wetland is a main component of WRSIS, and an important function of this constructed wetland is drainage water treatment of nitrog...

  1. Integrating pretreatment and denitrification in constructed wetland systems.

    PubMed

    Gonzalo, O G; Ruiz, I; Soto, M

    2017-02-08

    The aim of this work was to study the operational characteristics and the efficiency of a compact constructed wetland system for municipal wastewater treatment that integrates denitrification in the pre-treatment unit. The proposed system was simulated by two units in series with effluent recirculation, the first one being an anoxic digester, conceived as a hydrolytic up flow sludge bed for solids hydrolysis and denitrification, and the second one a sand column that simulated the operation of a vertical flow constructed wetland. The hybrid system consisted of two small columns of 4 and 10.2cm in diameter (anoxic digester and vertical flow unit, respectively). The unplanted system was operated successively with synthetic and real municipal wastewater over a period of 136days. Hydraulic loading rate ranged from 212 to 318mm/day and surface loading rate from 122 to 145g/m(2)·day of chemical oxygen demand and 10-15g/m(2)·day of total nitrogen for the overall system. The overall system reached removals of 91% to 99% for total suspended solids, chemical oxygen demand and biochemical oxygen demand whilst total nitrogen removal ranged from 43% to 61%. In addition to suspended solids removal (up to 78%), the anoxic digester provided high denitrification rates (3-12gN/m(2)·day) whilst the vertical flow unit provided high nitrification rates (8-15gN/m(2)·day). Organic matter was mainly removed in the anoxic digester (63-82% chemical oxygen demand) and used for denitrification. Final effluent concentration was lower for ammonia (7.4±2.4mgN/L on average) than for nitrate (19.8±4.4mgN/L), denitrification appearing as the limiting step in nitrogen removal in the system. CH4 or N2O emissions were not detected in any of the units of the system indicating very low greenhouse gas emissions.

  2. Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment ▿

    PubMed Central

    Graczyk, Thaddeus K.; Lucy, Frances E.; Tamang, Leena; Mashinski, Yessika; Broaders, Michael A.; Connolly, Michelle; Cheng, Hui-Wen A.

    2009-01-01

    Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, −84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this

  3. Application of a constructed wetland for non-point source pollution control.

    PubMed

    Kao, C M; Wang, J Y; Lee, H Y; Wen, C K

    2001-01-01

    In Taiwan, non-point source (NPS) pollution is one of the major causes of impairment of surface waters. The main objective of this study was to evaluate the efficacy of using constructed wetlands on NPS pollutant removal and water quality improvements. A field-scale constructed wetland system was built inside the campus of National Sun Yat-Sen University (located in southern Taiwan) to remove (1) NPS pollutants due to the stormwater runoff, and (2) part of the untreated wastewater from school drains. The constructed wetland was 40 m (L) x 30 m (W) x 1 m (D), which received approximately 85 m3 per day of untreated wastewater from school drainage pipes. The plants grown on the wetland included floating (Pistia stratiotes L.) and emergent (Phragmites communis L.) species. One major storm event and baseline water quality samples were analyzed during the monitoring period. Analytical results indicate that the constructed wetland removed a significant amount of NPS pollutants and wastewater constituents. More than 88% of nitrogen, 81% of chemical oxygen demand (COD), 85% of heavy metals, and 60% of the total suspended solids (TSS) caused by the storm runoff were removed by the wetland system before discharging. Results from this study may be applied to the design of constructed wetlands for NPS pollution control and water quality improvement.

  4. STORMWATER TREATMENT: WET/DRY PONDS VS. CONSTRUCTED WETLANDS

    EPA Science Inventory

    Extant data were used to assess the relative effectiveness of ponds vs. wetland-type BMPs. Compared to wet ponds, wetlands tended toward higher constituent concentrations in effluent, were inefficient at nitrogen removal, and appeared to preferentially retain phosphorous. These d...

  5. CWM1: a general model to describe biokinetic processes in subsurface flow constructed wetlands.

    PubMed

    Langergraber, Guenter; Rousseau, Diederik P L; García, Joan; Mena, Javier

    2009-01-01

    This paper presents the Constructed Wetland Model No1 (CWM1), a general model to describe biochemical transformation and degradation processes for organic matter, nitrogen and sulphur in subsurface flow constructed wetlands. The main objective of CWM1 is to predict effluent concentrations from constructed wetlands without predicting gaseous emissions. CWM1 describes aerobic, anoxic and anaerobic processes and is therefore applicable to both horizontal and vertical flow systems. 17 processes and 16 components (8 soluble and 8 particulate) are considered. CWM1 is based on the mathematical formulation as introduced by the IWA Activated Sludge Models (ASMs). It is important to note that besides the biokinetic model a number of other processes including porous media hydrodynamics, the influence of plants, the transport of particles/suspended matter to describe clogging processes, adsorption and desorption processes and physical re-aeration must be considered for the formulation of a full model for constructed wetlands.

  6. Sequential nitrification/identification in subsurface flow constructed wetlands. A literature review. Master's thesis

    SciTech Connect

    Titus, F.W.

    1992-12-01

    Even though there is currently no consensus on the design of subsurface flow constructed wetlands, the ability of constructed wetlands to meet municipal wastewater requirements is well documented. Nitrogen removal appears from the existing performance data to be one of the primary problems with these systems. The negative effects of excessive levels of nitrogen on the aquatic environment include eutrophication of receiving waters and the increased risk of methemoglobinemia in human infants where elevated levels of nitrate (NO3-) or nitrite (NO2-) nitrogen are present in drinking water supplies. The performance of constructed wetlands for nitrogen removal, at best, can be rated poor to fair. As a result of the negative effects of excessive nitrogen on the environment and the problems with constructed wetlands in consistently removing nitrogen to within acceptable levels, this report will be directed towards the sequential nitrification/denitrification process.

  7. EVALUATION OF CONSTRUCTED WETLAND AND RETENTION POND BMPS FOR ATTENUATING MICROBIAL CONTAMINANTS IN URBAN STORMWATER RUNOFF

    EPA Science Inventory

    This project investigated the use of constructed wetlands and retention ponds for decreasing microbial concentrations from urban stormwater runoff. Increased urbanization has resulted in a larger percentage of impervious areas which cause large quantities of stormwater runoff an...

  8. EVALUATION OF CONSTRUCTED WETLAND AND RETENTION POND BMPS FOR ATTENUATING MICROBIAL CONTAMINANTS IN URBAN STORMWATER RUNOFF

    EPA Science Inventory

    This project investigated the use of constructed wetlands and retention ponds for decreasing microbial concentrations from urban stormwater runoff. Increased urbanization has resulted in a larger percentage of impervious areas which cause large quantities of stormwater runoff an...

  9. Constructed Wetlands Revisited: Microbial Diversity in the -omics Era.

    PubMed

    Sánchez, Olga

    2017-04-01

    Constructed wetlands (CWs) constitute an interesting alternative option to conventional systems for wastewater treatment. This technology is based on the utilization of the concerted activity of microorganisms for the removal of contaminants. Consequently, knowledge on the microbial assemblages dwelling CWs and the different environmental factors which can alter their activities is crucial for understanding their performance. In the last decades, the use of molecular techniques to characterize these communities and more recently, application of -omics tools, have broaden our view of microbial diversity and function in wastewater microbiology. In this manuscript, a review of the current knowledge on microbial diversity in CWs is offered, placing particular emphasis on the different molecular studies carried out in this field. The effect of environmental conditions, such as plant species, hydraulic design, water depth, organic carbon, temperature and substrate type on prokaryotic communities has been carefully revised, and the different studies highlight the importance of these factors in carbon, nitrogen and sulfur cycles. Overall, the novel -omics open a new horizon to study the diversity and ecophysiology of microbial assemblages and their interactions in CWs, particularly for those microorganisms belonging to the rare biosphere not detectable with conventional molecular techniques.

  10. Design and optimisation of novel configurations of stormwater constructed wetlands

    NASA Astrophysics Data System (ADS)

    Kiiza, Christopher

    2017-04-01

    Constructed wetlands (CWs) are recognised as a cost-effective technology for wastewater treatment. CWs have been deployed and could be retrofitted into existing urban drainage systems to prevent surface water pollution, attenuate floods and act as sources for reusable water. However, there exist numerous criteria for design configuration and operation of CWs. The aim of the study was to examine effects of design and operational variables on performance of CWs. To achieve this, 8 novel designs of vertical flow CWs were continuously operated and monitored (weekly) for 2years. Pollutant removal efficiency in each CW unit was evaluated from physico-chemical analyses of influent and effluent water samples. Hybrid optimised multi-layer perceptron artificial neural networks (MLP ANNs) were applied to simulate treatment efficiency in the CWs. Subsequently, predictive and analytical models were developed for each design unit. Results show models have sound generalisation abilities; with various design configurations and operational variables influencing performance of CWs. Although some design configurations attained faster and higher removal efficiencies than others; all 8 CW designs produced effluents permissible for discharge into watercourses with strict regulatory standards.

  11. Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater.

    PubMed

    Coban, Oksana; Kuschk, Peter; Wells, Naomi S; Strauch, Gerhard; Knoeller, Kay

    2015-09-01

    Pathways of ammonium (NH4 (+)) removal were investigated using the stable isotope approach in constructed wetlands (CWs). We investigated and compared several types of CWs: planted horizontal subsurface flow (HSSF), unplanted HSSF, and floating plant root mat (FPRM), including spatial and seasonal variations. Plant presence was the key factor influencing efficiency of NH4 (+) removal in all CWs, what was illustrated by lower NH4 (+)-N removal by the unplanted HSSF CW in comparison with planted CWs. No statistically significant differences in NH4 (+) removal efficiencies between seasons were detected. Even though plant uptake accounted for 32-100 % of NH4 (+) removal during spring and summer in planted CWs, throughout the year, most of NH4 (+) was removed via simultaneous nitrification-denitrification, what was clearly shown by linear increase of δ(15)N-NH4 (+) with decrease of loads along the flow path and absence of nitrate (NO3 (-)) accumulation. Average yearly enrichment factor for nitrification was -7.9 ‰ for planted HSSF CW and -5.8 ‰ for FPRM. Lack of enrichment for δ(15)N-NO3 (-) implied that other processes, such as nitrification and mineralization were superimposed on denitrification and makes the stable isotope approach unsuitable for the estimation of denitrification in the systems obtaining NH4 (+) rich inflow water.

  12. Performance of constructed wetland system for public water supply.

    PubMed

    Elias, J M; Salati Filho, E; Salati, E

    2001-01-01

    The project is being conducted in the town of Analândia, São Paulo, Brazil. The constructed wetlands system for water supply consists of a channel with floating aquatic macrophytes, HDS system (Water Decontamination with Soil-Patent PI 850.3030), chlorinating system, filtering system and distribution. The project objectives include investigating the process variables to further optimize design and operation factors, evaluating the relation of nutrients and plants development, biomass production, shoot development, nutrient cycling and total and fecal coliforms removal, comparing the treatment efficiency among the seasons of the year; and moreover to compare the average values obtained between February and June 1998 (Salati et al., 1998) with the average obtained for the same parameters between March and June 2000. Studies have been developed in order to verify during one year the drinking quality of the water for the following parameters: turbidity, color, pH, dissolved oxygen, total of dissolved solids, COD, chloride, among others, according to the Ministry of Health's Regulation 36. This system of water supply projected to treat 15 L s(-1) has been in continuous operation for 2 years, it was implemented with support of the National Environment Fund (FNMA), administered by the Center of Environmental Studies (CEA-UNESP), while the technical supervision and design were performed by the Institute of Applied Ecology. The actual research project is being supported by FAPESP.

  13. Comparison of interannual removal variation of various constructed wetland types.

    PubMed

    Hijosa-Valsero, María; Sidrach-Cardona, Ricardo; Bécares, Eloy

    2012-07-15

    Seven mesocosm-scale (1m(2)) constructed wetlands (CWs) of different configurations were operated outdoors for thirty-nine months under the same conditions to assess their ability to remove organic matter and nutrients from urban wastewaters. CWs differed in some design parameters, namely the presence of plants, the species chosen (i.e., Typha angustifolia or Phragmites australis), the flow configuration (i.e., surface flow or subsurface flow) and the presence/absence of a gravel bed. It was observed that, in general, removal efficiencies decreased with the aging of the system and that seasonality had a great influence on CWs. A comparison was made in order to figure out which kind of CW was more efficient for the removal of every pollutant in the long term. Planted systems were clearly better than unplanted systems even in winter. Efficiency differences among CWs were not extremely great, especially after a few years. However, some types of CWs were more adequate for the removal of certain pollutants. The effect of the aging on the main parameters involved in pollutant removal in CWs (temperature, pH, conductivity, dissolved oxygen concentration and redox potential) was assessed. The efficiency of CWs should not be evaluated based on short monitoring periods (1-2 years) after the start-up of the systems, but on longer periods. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Multi-stage constructed wetland systems for municipal wastewater treatment.

    PubMed

    Masi, F; Caffaz, S; Ghrabi, A

    2013-01-01

    In the present paper the detailed design and performances of two municipal wastewater treatment plants, a four-stage constructed wetlands (CW) system located in the city of Dicomano (about 3,500 inhabitants) in Italy, and a three-stage CW system for the village of Chorfech (about 500 inhabitants) in Tunisia, are presented. The obtained results demonstrate that multi-stage CWs provide an excellent secondary treatment for wastewaters with variable operative conditions, reaching also an appropriate effluent quality for reuse. Dicomano CWs have shown good performances, on average 86% of removal for the Organic Load, 60% for Total Nitrogen (TN), 43% for Total Phosphorus (TP), 89% for Total Suspended Solids (TSS) and 76% for Ammonium (NH4(+)). Even the disinfection process has performed in a very satisfactory way, reaching up to 4-5 logs of reduction of the inlet pathogens concentration, with an Escherichia coli average concentration in the outlet often below 200 UFC/100 mL. The mean overall removal rates of the Chorfech CWs during the monitored period have been, respectively, equal to 97% for TSS and Biochemical Oxygen Demand (BOD5), 95% for Chemical Oxygen Demand (COD), 71% for TN and 82% for TP. The observed removal of E. coli by the CW system was in this case 2.5 log units.

  15. Reuse of constructed wetland effluents for irrigation of energy crops.

    PubMed

    Barbagallo, S; Barbera, A C; Cirelli, G L; Milani, M; Toscano, A

    2014-01-01

    The aim of this study was to evaluate biomass production of promising 'no-food' energy crops, Vetiveria zizanoides (L.) Nash, Miscanthus × giganteus Greef et Deu. and Arundo donax (L.), irrigated with low quality water at different evapotranspiration restitutions. Two horizontal subsurface flow (H-SSF) constructed wetland (CW) beds, with different operation life (12 and 6 years), were used to treat secondary municipal wastewaters for crop irrigation. Water chemical, physical and microbiological parameters as well as plant bio-agronomic characters were evaluated. The results confirm the high reliability of CWs for tertiary wastewater treatment given that the H-SSF1 treatment capacity remained largely unchanged after 12 years of operation. Average total suspended solids, chemical oxygen demand and total nitrogen removal for CWs were about 68, 58 and 71%, respectively. The Escherichia coli removal was satisfactory, about 3.3 log unit for both CW beds on average, but caution should be taken as this parameter did not achieve the restrictive Italian law limits for wastewater reuse. The average above-ground dry matter productions were 7 t ha⁻¹ for Vetiveria zizanoides, 24 t ha⁻¹ for Miscanthus × giganteus and 50 t ha⁻¹ for Arundo donax. These results highlight attractive biomass yield by using treated wastewater for irrigation with a complete restitution of evapotranspiration losses.

  16. Mathematical model for analysis of recirculating vertical flow constructed wetlands.

    PubMed

    Sklarz, Menachem Y; Gross, Amit; Soares, M Ines M; Yakirevich, Alexander

    2010-03-01

    The recirculating vertical flow constructed wetland (RVFCW) was developed for the treatment of domestic wastewater (DWW). In this system, DWW is applied to a vertical flow bed through which it trickles into a reservoir located beneath the bed. It is then recirculated back to the root zone of the bed. In this study, a compartmental model was developed to simulate the RVFCW. The model, which addresses transport and removal kinetics of total suspended solids, 5-day biological oxygen demand and nitrogen, was fitted to kinetical results obtained from pilot field setups and a local sensitivity analysis was performed on the model parameters and operational conditions. This analysis showed that after 5h of treatment water quality is affected more by stochastic events than by the model parameter values, emphasizing the stability of the RVFCW system to large variations in operational conditions. Effluent quality after 1h of treatment, when the sensitivity analysis showed the parameter impacts to be largest, was compared to model predictions. The removal rate was found to be dependent on the recirculation rate. The predictions correlated well with experimental observations, leading to the conclusion that the proposed model is a satisfactory tool for studying RVFCWs. Copyright 2009 Elsevier Ltd. All rights reserved.

  17. Evaluation of recharge to the Skunk Creek Aquifer from a constructed wetland near Lyons, South Dakota

    USGS Publications Warehouse

    Thompson, Ryan F.

    2002-01-01

    A wetland was constructed in the Skunk Creek flood plain near Lyons in southeast South Dakota to mitigate for wetland areas that were filled during construction of a municipal golf course for the city of Sioux Falls. A water-rights permit was obtained to allow the city to pump water from Skunk Creek into the wetland during times when the wetland would be dry. The amount of water seeping through the wetland and recharging the underlying Skunk Creek aquifer was not known. The U.S. Geological Survey, in cooperation with the city of Sioux Falls, conducted a study during 1997-2000 to evaluate recharge to the Skunk Creek aquifer from the constructed wetland. Three methods were used to estimate recharge from the wetland to the aquifer: (1) analysis of the rate of water-level decline during periods of no inflow; (2) flow-net analysis; and (3) analysis of the hydrologic budget. The hydrologic budget also was used to evaluate the efficiency of recharge from the wetland to the aquifer. Recharge rates estimated by analysis of shut-off events ranged from 0.21 to 0.82 foot per day, but these estimates may be influenced by possible errors in volume calculations. Recharge rates determined by flow-net analysis were calculated using selected values of hydraulic conductivity and ranged from 566,000 gallons per day using a hydraulic conductivity of 0.5 foot per day to 1,684,000 gallons per day using a hydraulic conductivity of 1.0 foot per day. Recharge rates from the hydrologic budget varied from 0.74 to 0.85 foot per day, and averaged 0.79 foot per day. The amount of water lost to evapotranspiration at the study wetland is very small compared to the amount of water seeping from the wetland into the aquifer. Based on the hydrologic budget, the average recharge efficiency was estimated as 97.9 percent, which indicates that recharging the Skunk Creek aquifer by pumping water into the study wetland is highly efficient. Because the Skunk Creek aquifer is composed of sand and gravel, the

  18. Examination of oxygen release from plants in constructed wetlands in different stages of wetland plant life cycle.

    PubMed

    Zhang, Jian; Wu, Haiming; Hu, Zhen; Liang, Shuang; Fan, Jinlin

    2014-01-01

    The quantification of oxygen release by plants in different stages of wetland plant life cycle was made in this study. Results obtained from 1 year measurement in subsurface wetland microcosms demonstrated that oxygen release from Phragmites australis varied from 108.89 to 404.44 mg O₂/m(2)/d during the different periods from budding to dormancy. Plant species, substrate types, and culture solutions had a significant effect on the capacity of oxygen release of wetland plants. Oxygen supply by wetland plants was estimated to potentially support a removal of 300.37 mg COD/m(2)/d or 55.87 mg NH₄-N/m(2)/d. According to oxygen balance analysis, oxygen release by plants could provide 0.43-1.12% of biochemical oxygen demand in typical subsurface-flow constructed wetlands (CWs). This demonstrates that oxygen release of plants may be a potential source for pollutants removal especially in low-loaded CWs. The results make it possible to quantify the role of plants in wastewater purification.

  19. Enhanced phosphorus removal in intermittently aerated constructed wetlands filled with various construction wastes.

    PubMed

    Shi, Xia; Fan, Jinlin; Zhang, Jian; Shen, Youhao

    2017-08-13

    Phosphorus (P) loss by various pathways in constructed wetlands (CWs) is often variable. The effects of intermittent aeration and different construction waste substrates (gravel, red brick, fly-ash brick) on P processing using six batch-operated vertical flow constructed wetlands (VFCWs) were studied for decentralized domestic wastewater treatment. Average removal of total phosphorus (TP) in three aerated CWs was markedly higher (21.06, 24.83, and 27.02 mg m(-2) day(-1), respectively) than non-aerated CWs (10.64, 18.16, and 25.09 mg m(-2) day(-1), respectively). Fly-ash brick offered superior TP removal efficiency in both aerated and non-aerated batch-operated VFCWs, suggesting its promising application for P removal in CWs. Aeration greatly promoted plant growth and thusly increased plant uptake of P by 0.57-1.45 times. Substance storage was still the main P sink accounting for 23.92-59.47% of TP removal. Other process including microbial uptake was revealed to be a very important P removal pathway (accounting for 14.86-34.84%). The contribution of microbial uptake was also indicated by microbial analysis. Long-term results suggested that the contribution of microbial P uptake could be always ignored and underestimated in most CWs. A combination of intermittent aeration and suitable substrates is effective to intensify P transformation in CWs.

  20. Construction simplicity and cost as selection criteria between two types of constructed wetlands treating highway runoff.

    PubMed

    Manios, Thrassyvoulos; Fountoulakis, Michalis S; Karathanasis, Anastasios D

    2009-05-01

    Two free water surface (FWS) and two subsurface flow (SSF) pilot-size wetlands were constructed for the evaluation of their performance in treating highway runoff (HRO) in the heart of the Mediterranean region, the island of Crete, at the southernmost point of Greece. Detailed recordings of the resources involved during the construction allowed a thorough calculation of the cost of the systems and the requirements in materials, man-hours, and equipment. The two identical FWS systems had a surface area of 33 m(2) each, while the two identical SSF covered 32 m(2) each. One FWS and one SSF, named FWS12 and SSF12, respectively, were designed with a hydraulic retention time (HRT) of 12 h, with each one capable of treating a maximum HRO of 12.6 m(3)/day. The other couple, named FWS24 and SSF24, respectively, was designed with an HRT of 24 h, with each receiving a maximum HRO of 6.3 m(3)/days. An influent storage tank was required to hold the runoff during the common storm events and control the flow rate (and the hydraulic retention time) into the wetlands. This construction represented 25% of the total construction cost, while 5% was spent on the influent automated (and sun-powered) control and distribution system, from the storage tank to the wetlands. The respective total cost allocated to the two SSF systems (euro 14,676) was approximately 10% higher than that of the FWS (euro 13,596), mainly due to the three different-sized gravel layers used in the SSF substrate compared to the topsoil used in the FWS, which tripled the cost and placement time. The Total Annual Economic Cost (TAEC) was euro 1799/year and euro 1847/year for the FWS and SSF pair, respectively. TAEC was also used to compare the economic efficiency of the systems per cubic meter of HRO treated and kilograms of COD and TSS removed from the wetlands during their first operational year. Based on these estimations, FWS12 recorded the lowest TAEC(COD) and TAEC(TSS) values (euro 89.09/kg and euro 43.69/kg

  1. Tolerance to hydraulic and organic load fluctuations in constructed wetlands.

    PubMed

    Masi, F; Martinuzzi, N; Bresciani, R; Giovannelli, L; Conte, G

    2007-01-01

    This paper describes a two-year performance evaluation of four different constructed wetland (CW) treatment systems designed by IRIDRA Srl, located in central Italy. All four CW systems were established to treat wastewater effluent from different tourist activities: (1) one single-stage CW for secondary treatment of domestic wastewater (30 p.e.) at a holiday farm site; (2) a hybrid compact system consisting of two stages, a horizontal flow (HF) system followed by a vertical flow (VF) system for the secondary treatment of effluent from a 140 p.e. tourist resort; (3) a single-stage vertical flow (VF) CW for a 100 p.e. mountain shelter; and (4) a pair of single-stage, HF CWs for the secondary treatment of segregated grey and black water produced by an 80 p.e. camping site. These tourism facilities are located in remote areas and share some common characteristics concerning their water management: they have high variability of water consumption and wastewater flow, depending on the season, weather and weekly regularities; they have no connection to a public sewer and most sites are located in a sensitive environment. Total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonium (N-NH4+), nitrate (N-NOx), total nitrogen (Ntot), total phosphorus (Ptot), total coliform (TC), faecal coliform (FC), E. coli removal efficiencies for all four CW systems are presented. The results from this study demonstrate the potential of CWs as a suitable technology for treating wastewater from tourism facilities in remote areas. A very efficient COD reduction (83-95%) and pathogen elimination (3-5 logs) have been achieved. Furthermore, the CWs are easily maintained, robust (not sensitive to peak flows), constructed with local materials, and operate with relatively low cost.

  2. Indicator pathogens, organic matter and LAS detergent removal from wastewater by constructed subsurface wetlands

    PubMed Central

    2014-01-01

    Background Constructed wetland is one of the natural methods of municipal and industrial wastewater treatments with low initial costs for construction and operation as well as easy maintenance. The main objective of this study is to determine the values of indicator bacteria removal, organic matter, TSS, ammonia and nitrate affecting the wetland removal efficiency. Results The average concentration of E. coli and total coliform in the input is 1.127 × 1014 and 4.41 × 1014 MPN/100 mL that reached 5.03 × 1012 and 1.13 × 1014 MPN/100 mL by reducing 95.5% and 74.4% in wetland 2. Fecal streptococcus reached from the average 5.88 × 1014 in raw wastewater to 9.69 × 1012 in the output of wetland 2. Wetland 2 could reduce 1.5 logarithmic units of E. coli. The removal efficiency of TSS for the wetlands is 68.87%, 71.4%, 57.3%, and 66% respectively. Conclusions The overall results show that wetlands in which herbs were planted had a high removal efficiency about the indicator pathogens, organic matter, LAS detergent in comparison to a control wetland (without canes) and could improve physicochemical parameters (DO, ammonia, nitrate, electrical conductivity, and pH) of wastewater. PMID:24581277

  3. The influence of urbanisation on macroinvertebrate biodiversity in constructed stormwater wetlands.

    PubMed

    Mackintosh, Teresa J; Davis, Jenny A; Thompson, Ross M

    2015-12-01

    The construction of wetlands in urban environments is primarily carried out to assist in the removal of contaminants from wastewaters; however, these wetlands have the added benefit of providing habitat for aquatic invertebrates, fish and waterbirds. Stormwater quantity and quality is directly related to impervious area (roads, sealed areas, roofs) in the catchment. As a consequence, it would be expected that impervious area would be related to contaminant load and biodiversity in receiving waters such as urban wetlands. This study aimed to establish whether the degree of urbanisation and its associated changes to stormwater runoff affected macroinvertebrate richness and abundance within constructed wetlands. Urban wetlands in Melbourne's west and south east were sampled along a gradient of urbanisation. There was a significant negative relationship between total imperviousness (TI) and the abundance of aquatic invertebrates detected for sites in the west, but not in the south east. However macroinvertebrate communities were relatively homogenous both within and between all study wetlands. Chironomidae (non-biting midges) was the most abundant family recorded at the majority of sites. Chironomids are able to tolerate a wide array of environmental conditions, including eutrophic and anoxic conditions. Their prevalence suggests that water quality is impaired in these systems, regardless of degree of urbanisation, although the causal mechanism is unclear. These results show some dependency between receiving wetland condition and the degree of urbanisation of the catchment, but suggest that other factors may be as important in determining the value of urban wetlands as habitat for wildlife.

  4. Influence of environmental variables on the structure and composition of soil bacterial communities in natural and constructed wetlands.

    PubMed

    Arroyo, Paula; Sáenz de Miera, Luis E; Ansola, Gemma

    2015-02-15

    Bacteria are key players in wetland ecosystems, however many essential aspects regarding the ecology of wetland bacterial communities remain unknown. The present study characterizes soil bacterial communities from natural and constructed wetlands through the pyrosequencing of 16S rDNA genes in order to evaluate the influence of wetland variables on bacterial community composition and structure. The results show that the composition of soil bacterial communities was significantly associated with the wetland type (natural or constructed wetland), the type of environment (lagoon, Typha or Salix) and three continuous parameters (SOM, COD and TKN). However, no clear associations were observed with soil pH. Bacterial diversity values were significantly lower in the constructed wetland with the highest inlet nutrient concentrations. The abundances of particular metabolic groups were also related to wetland characteristics.

  5. Effluent blending in constructed wetlands: Pollution prevention applications at a coal yard treatment facility

    SciTech Connect

    Carder, J.P.; Hoylman, A.M.; Sparks, B.J.

    1995-12-31

    Effluent blending, in combination with constructed wetland biotechnology, is a promising method for reducing the loading rates of pollution to receiving streams. At Oak Ridge National Laboratory, a project is underway to demonstrate this principle. An 8:2 ratio of sewage treatment plant to coal yard runoff treatment facility (CYRTF) effluent will be polished by 2 constructed wetland cells containing emergent wetland plants in saturated pea gravel at a rate of 3600 gallons per day. The relatively high concentration of nutrients in the STP effluent should stimulate biological processes leading to the reduction of chemical oxygen demand and the conversion of excess sulfate (in the CYRTF effluent) to alkalinity. Chlorine, which is added to the STP effluent to control bacteria, should also be eliminated. Measurements of wastewater toxicity, before and after the effluent blend has passed through the constructed wetlands, will be used to assess the technology`s effectiveness at reducing pollution.

  6. The performance of constructed wetlands for, wastewater treatment: a case study of Splash wetland in Nairobi Kenya

    NASA Astrophysics Data System (ADS)

    Nzengy'a, Daniel Muasya; Wishitemi, B. E. L.

    2001-12-01

    The performance of a constructed wetland for wastewater treatment was examined for four months (December 1995 to March 1996). The study area, hereby referred to as the Splash wetland, is approximately 0·5 ha, and is located in the southern part of Nairobi city. Splash wetland continuously receives domestic sewage from two busy restaurants. Treated wastewater is recycled for re-use for various purposes in the restaurants. Both wet and dry season data were analysed with a view of determining the impact of seasonal variation on the system performance. The physical and chemical properties of water were measured at a common intake and at series of seven other points established along the wetland gradient and at the outlet where the water is collected and pumped for re-use at the restaurants. The physico-chemical characteristics of the wastewater changed significantly as the wastewater flowed through the respective wetland cells. A comparison of wastewater influent versus the effluent from the wetland revealed the system's apparent success in water treatment, especially in pH modification, removal of suspended solids, organic load and nutrients mean influent pH = 5·7 +/- 0·5, mean effluent pH 7·7 +/- 0·3; mean influent BOD5 = 1603·0 +/- 397·6 mg/l, mean effluent BOD5 = 15·1 +/- 2·5 mg/l; mean influent COD = 3749·8 +/- 206·8 mg/l, mean effluent COD = 95·6 +/- 7·2 mg/l; mean influent TSS = 195·4 +/- 58·7 mg/l, mean effluent TSS = 4·7 +/- 1·9 mg/l. As the wastewater flowed through the wetland system dissolved free and saline ammonia, NH4+, decreased from 14·6 +/- 4·1 mg/l to undetectable levels at the outlet. Dissolved oxygen increased progressively through the wetland system. Analysis of the data available did not reveal temporal variation in the system's performance. However, significant spatial variation was evident as the wetland removed most of the common pollutants and considerably improved the quality of the water, making it safe for re-use at the

  7. A smart market for nutrient credit trading to incentivize wetland construction

    NASA Astrophysics Data System (ADS)

    Raffensperger, John F.; Prabodanie, R. A. Ranga; Kostel, Jill A.

    2017-03-01

    Nutrient trading and constructed wetlands are widely discussed solutions to reduce nutrient pollution. Nutrient markets usually include agricultural nonpoint sources and municipal and industrial point sources, but these markets rarely include investors who construct wetlands to sell nutrient reduction credits. We propose a new market design for trading nutrient credits, with both point source and non-point source traders, explicitly incorporating the option of landowners to build nutrient removal wetlands. The proposed trading program is designed as a smart market with centralized clearing, done with an optimization. The market design addresses the varying impacts of runoff over space and time, and the lumpiness of wetland investments. We simulated the market for the Big Bureau Creek watershed in north-central Illinois. We found that the proposed smart market would incentivize wetland construction by assuring reasonable payments for the ecosystem services provided. The proposed market mechanism selects wetland locations strategically taking into account both the cost and nutrient removal efficiencies. The centralized market produces locational prices that would incentivize farmers to reduce nutrients, which is voluntary. As we illustrate, wetland builders' participation in nutrient trading would enable the point sources and environmental organizations to buy low cost nutrient credits.

  8. Landowners' incentives for constructing wetlands in an agricultural area in south Sweden.

    PubMed

    Hansson, Anna; Pedersen, Eja; Weisner, Stefan E B

    2012-12-30

    Eutrophication of the Baltic Sea has in Sweden led to the initiation of government schemes aiming to increase wetland areas in agricultural regions and thereby reduce nutrient transport to the sea. Landowners play a significant role as providers of this ecosystem service and are currently offered subsidies to cover their costs for constructing and maintaining wetlands. We undertook a grounded theory study, in which landowners were interviewed, aiming at identifying landowners' incentives for constructing wetlands on their land. The study showed that adequate subsidies, additional services that the wetland could provide to the landowner, local environmental benefits, sufficient knowledge, and peers' good experiences could encourage landowners to construct wetlands. Perceived hindrances were burdensome management, deficient knowledge, time-consuming application procedures and unclear effectiveness of nutrient reduction. The main reason for not creating a wetland, however, was that the land was classified as productive by the landowner, i.e., suitable for food production. Current schemes are directed toward landowners as individuals and based on subsidies to cover costs. We propose that landowners instead are approached as ecosystem service entrepreneurs and contracted after a tendering process based on nutrient reduction effects. This would lead to new definitions of production and may stimulate improved design and placement of wetlands.

  9. Estrogenic activity and steroid hormones in swine wastewater through a lagoon constructed-wetland system.

    PubMed

    Shappell, Nancy W; Billey, Lloyd O; Forbes, Dean; Matheny, Terry A; Poach, Matthew E; Reddy, Gudigopuram B; Hunt, Patrick G

    2007-01-15

    Anaerobic lagoons and treatment wetlands are used worldwide to treat wastewater from dense livestock production facilities; however, there is very limited data on the hormonal activity of the wastewater effluent produced by these treatment systems. The objectives of this experiment were to measure (1) the hormonal activity of the initial effluent and (2) the effectiveness of a lagoon-constructed wetland treatment system for producing an effluent with a low hormonal activity. Wastewater samples were taken in April, July, and November 2004 and July 2005 from a lagoon-constructed wetland system at a swine farrowing facility. Estrogenic activity (in vitro E-screen assay), 17 beta-estradiol (E2), and testosterone concentrations (LC/MS-MS) were measured. A high correlation was found between estradiol equivalents determined by E-screen and LC/MS-MS (R2 = 0.82). Nutrient removal was measured to ensure that the wetlands were functioning in a manner similar to literature reports. Nutrient removals were typical for treatment wetlands: TKN 59-75% and orthophosphate 0-18%. Wetlands decreased estrogenic activity by 83-93%. Estrone was the most persistent estrogenic compound. Constructed wetlands produced effluents with estrogenic activity below the lowest equivalent E2 concentration known to have an effect on fish (10 ng/L or approximately 37 x 10(-12) M).

  10. Remediation of abandoned mine sites using constructed wetlands: A Colorado perspective

    SciTech Connect

    Ganse, M.A.; Herron, J.T.

    1995-09-01

    In recent years, constructed wetlands have been used to remediate acid mine drainage which has resulted from both coal and metal mining activities. These wetlands are use din conjunction with other engineered components to create a passive mine drainage treatment system (PMDT). Passive systems are designed to remediate mine drainage using minimum capital expenditures and little to no operational and maintenance costs. The Colorado Division of Minerals and Geology (DMG) is responsible for the design, construction, and operation of constructed wetlands in Colorado. Only 5 systems are in existence at this time, located in terrain varying from gentle foothills to remote, sub-alpine mountains. The design of a wetland system is based on a multitude of factors such as site terrain and access, mine drainage composition, and in the Rocky Mountain region, altitude. The impact of altitude, climate, terrain, and other physical site constraints on each wetland design will be discussed. In addition, chemical issues critical to the design of each wetland such as pH and alkalinity will be presented. Finally, the performance of each wetland system will be examined.

  11. [Difference of P content in different area substrate of constructed wetland].

    PubMed

    Cao, Xue-Ying; Chong, Yun-Xiao; Yu, Guang-Wei; Zhong, Hai-Tao

    2012-11-01

    Adsorption of substrate is the main removal mechanisms of phosphorus in constructed wetland. It is easily impacted by various environmental factors existing in the wetland bed. The contents of substrate TP and the main inorganic P in different areas of both horizontal sub-surface flow constructed wetland with plant and one without plant were measured after treating wastewater five months. Different areas of the wetland with plant differed greatly in the substrate TP. Rhizosphere substrate in front area had the highest TP content and achieved 0.75 g x kg(-1), and the TP content of non-rhizosphere substrate in back area was only 0.21 g x kg(-1). The TP content of substrate in different areas of the wetland without plant had a little variety and ranged only between 0.21 and 0.27 g x kg(-1). Averagely, the substrate TP content in the wetland with plant was higher than the one in the wetland without plant. The phosphorous with Fe-bound (Fe-P), Al-bound (Al-P), and Ca-bound (Ca-P) were main inorganic phosphorous existing in the substrate in both wetlands, their contents in different areas substrate all increased, compared with the one before experiment. Fe-P and Al-P in different substrates in both wetlands had a similar variety. Their content between rhizosphere and intermediate substrate of front area in the wetland with plant and other area substrate in both wetlands differed greatly because the former increased greatly. Compared with Fe-P and Al-P, the variety of Ca-P in different substrates in both wetlands was low. But the content of Ca-P in rhizosphere substrate in wetland with plant was higher than other two parts respectively in front and back areas. Obviously, the plant root had an impact on the phosphorous content of substrate in constructed wetland. For TP, Fe-P, Al-P, Ca-P and loosely sorbed phosphorous in substrate, it increased with distance of the root.

  12. Simultaneous removal of nitrate and sulfate from greenhouse wastewater by constructed wetlands.

    PubMed

    Gruyer, Nicolas; Dorais, Martine; Alsanius, Beatrix W; Zagury, Gérald J

    2013-07-01

    This study evaluated the effectiveness of C-enriched subsurface-flow constructed wetlands in reducing high concentrations of nitrate (NO) and sulfate (SO) in greenhouse wastewaters. Constructed wetlands were filled with pozzolana, planted with common cattail (), and supplemented as follows: (i) constructed wetland with sucrose (CW+S), wetland units with 2 g L of sucrose solution from week 1 to 28; (ii) constructed wetland with compost (CW+C), wetland units supplemented with a reactive mixture of compost and sawdust; (iii) constructed wetland with compost and no sucrose (CW+CNS) from week 1 to 18, and constructed wetland with compost and sucrose (CW+CS) at 2 g L from week 19 to 28; and (iv) constructed wetland (CW). During 28 wk, the wetlands received a typical reconstituted greenhouse wastewater containing 500 mg L SO and 300 mg L NO. In CW+S, CW+C, and CW+CS, appropriate C:N ratio (7:3.4) and redox potential (-53 to 39 mV) for denitrification resulted in 95 to 99% NO removal. Carbon source was not a limiting factor for denitrification in C-enriched constructed wetlands. In CW+S and CW+CS, the dissolved organic carbon (DOC)/SO ratios of 0.36 and 0.28 resulted in high sulfate-reducing bacteria (SRB) counts and high SO removal (98%), whereas low activities were observed at DOC/SO ratios of 0.02 (CW) to 0.11 (CW+C, CW+CNS). On week 19, when organic C content was increased by sucrose addition in CW+CS, SRB counts increased from 2.80 to 5.11 log[CFU+1] mL, resulting in a level similar to the one measured in CW+S (4.69 log[CFU+1] mL). Consequently, high sulfate reduction occurred after denitrification, suggesting that low DOC (38-54 mg L) was the limiting factor. In CW, DOC concentration (9-10 mg L) was too low to sustain efficient denitrification and, therefore, sulfate reduction. Furthermore, the high concentration of dissolved sulfides observed in CW+S and CW+CS treated waters were eliminated by adding FeCl.

  13. Subsurface Treatment of Domestic Wastewater Using Single Domicile Constructed Wetlands

    NASA Astrophysics Data System (ADS)

    Aseltyne, T.; Steer, D.; Fraser, L.

    2001-05-01

    Analysis of one year of input versus output water quality monitoring data from nine household wastewater treatment wetlands in western Ohio indicates that these systems substantially reduce effluent loads delivered to the local watershed. Overall performance as measured by output water quality improvement varies widely between the nine systems despite their close proximity and identical design. These three-cell systems (septic tank with 2 subsurface wetland cells) are found to reduce biological oxygen demand (BOD) 70-98%, fecal coliform 60-99.9%, NH3 29-97%, Phosphorus 21-99.9% and total suspended solids (TSS) up to 97%. NO3/NO2 readings were only taken at the second wetland cell, but show that NO3/NO2 levels are at 0.005-5.01 mg/l and well below the USEPA standards for discharge from a wetland. On average, the pH of the wastewater increases from 6.6 at the septic tank to 8.7 at the wetland output. Nearly all the monitoring data indicate clear decreases in nutrient loads and bacteria though individual systems are found to non-systematically fail to meet EPA discharge guidelines for one or more of the monitored loads. Preliminary analysis of the data indicates a decrease in overall efficiency of the wetlands in April that may be related to seasonal factors. These systems will be monitored for the next three years in order to relate changing performance trends to seasonal variability.

  14. [Effect of the subsurface constructed wetland evolution into free surface flow constructed wetland on the removal of organic matter, nitrogen, and phosphor in wastewater].

    PubMed

    Wei, Ze-Jun; Xie, Jian-Ping; Huang, Yu-Ming

    2012-11-01

    Many previous studies demonstrated that the performance of the subsurface constructed wetlands (SSCW) for wastewater treatment was superior to that of the free flow surface constructed wetlands (FFSCW). However, our results indicated that the performance of FFSCW derived from the evolution of SSCW due to clogging for COD, TOC, total nitrogen (TN), and total phosphor (TP) removal was higher than those of SSCW with the same substrate and plant. The laboratory culture experiments were adopted to evaluate the effect of the constructed wetland evolution on the organic matter mineralization, nitrification/denitrification as well as removal of nitrogen and phosphor. It was shown that, after evolution of SSCW into FFSCW, the mineralization rate for organic matter (as TOC) was 1.82 mg x h(-1), and it was 1.49 mg x h(-1) for SSCW. The removal efficiency for NO3(-) was 96.8%, and it was 58.1% for SSCW. The abiotic denitrification removal efficiency was 40%, and it was 28.2% for SSCW. In addition, the maximum equilibrium adsorption capacity of the substrate after evolution for phosphor (as P) was 160 mg x kg(-1), and it was 140 mg x kg(-1) for SSCW substrate. The organic coverage of the substrate was found to be beneficial to phosphor removal. The nitrification ability decreased after evolution. These results suggest the important effect of constructed wetland evolution on its performance.

  15. Evaluation of unclogging aspects in horizontal subsurface flow constructed wetlands.

    PubMed

    Miranda, Suymara Toledo; de Matos, Antonio Teixeira; Baptestini, Gheila Corrêa Ferres; Borges, Alisson Carraro

    2016-10-01

    In horizontal subsurface flow constructed wetlands (HSSF-CWs), the main operational problem is clogging of the porous medium. In this study, the unclogging of HSSF-CWs was evaluated, at rest, by adding a nitrogen-based nutrient solution to the influent. For this, six HSSF-CWs were used, consisting of two uncultivated (CW-C), two cultivated with Tifton 85-grass (Cynodon spp.) (CW-T) and two cultivated with alligator weed (Alternanthera philoxeroides) (CW-A), which were fully clogged after being used for the treatment of swine wastewater. The results indicated that passage of the nutrient solution for 55 days through the bed of the HSSF-CWs resulted in reductions of 11 and 33%, respectively, in the total volatile solids (TVS) concentration of fine clogging material in the CW-T and CW-A. With regard to the TVS content of the coarse clogging material, the reduction was even greater, being 33% for CW-T and 62% for CW-A. Measurements of K0 made along the beds (thirds 1, 2 and 3) before and after passage of the nutrient solution in the CWs indicated respective increases of 7, 13 and 0.1% in CW-C; 21, 11 and 7% in CW-T; and 52%, 6% and -6% (decrease) in CW-A. Runoff of the nutrient solution decreased gradually over time, presenting at the beginning of the experiment 26, 35 and 150 cm, and at the end (after 55 days of application) 0, 0 and 50 cm in the flow direction of the CW-C and CW-T and CW-A, respectively.

  16. Polar organic solvent removal in microcosm constructed wetlands.

    PubMed

    Grove, Janet Kowles; Stein, Otto R

    2005-10-01

    Three polar organic solvents, acetone, tetrahydrofuran (THF) and 1-butanol, were added at 100 mg/l each to post-primary municipal wastewater in order to simulate a mixed waste stream. This mixture was applied to an experimental microcosm subsurface constructed wetland system consisting of replicates of Juncus effusus, Carex lurida, Iris pseudacorus, Pondeteria cordata and unplanted controls in a series of 14-day batch incubations over a yearlong period simulating a summer and winter season. 90% removal of 1-butanol typically took less than 3 days. 90% removal of acetone required from 5 to 10 days in summer and 10 to 14 days in winter. 90% removal of THF required at least 10 days and was frequently not achieved during the 14-day incubations. Initial experiments confirmed that the majority of solvent removal was via microbial bioremediation. Solvent removal was typically better in planted replicates, especially Juncus, regardless of season. The removal rate of all solvents was slower in winter, but the seasonal effect was most pronounced in the unplanted control replicates and least in the Carex and Juncus replicates. Plant and seasonal effects are believed to be due, in part, to variation in metabolic pathways induced by plant and seasonal variation in available root-zone oxygen. Variation in transpiration also influenced species and seasonal effects on THF removal, but not the other more biodegradable solvents. A model based on a prediction of plant uptake of nonionic dissolved chemicals suggests that as much as 39% of the THF in solution could have been removed through plant transpiration.

  17. Sediment from Agricultural Constructed Wetland Immobilizes Soil Phosphorus.

    PubMed

    Laakso, Johanna; Uusitalo, Risto; Leppänen, Janette; Yli-Halla, Markku

    2017-03-01

    Phosphorus (P) losses from agricultural soils impair the quality of receiving surface waters by enhancing eutrophication. This study tested the potential of using sediment from agricultural constructed wetlands (CWs) to immobilize soil P using two soils differing in texture and soil test P (STP). A silty clay soil (SIC) with high STP (24 mg ammonium acetate-extractable P [P] L) and a sandy loam soil (SL) with excessive STP (210 mg P L) were incubated with increasing amounts of clayey CW sediment. The soil-sediment mixtures were studied with the quantity/intensity (Q/I) technique, using chemical extractions, and by exposing the mixtures to simulated rainfall. In both Q/I and simulated rainfall tests, P solubility steadily decreased with increasing sediment proportion in the mixtures. However, in chemical extractions this effect was observed only at high sediment addition rates (10 or 50% [v/v] sediment). At a practically feasible sediment addition rate of 5%, dissolved reactive P (DRP) in percolating water from simulated rainfall decreased by 55% in SIC and by 54% in SL ( < 0.001 in both cases). Particulate P (PP) also showed a decreasing trend with increasing sediment addition rate. Upon prolonged simulated rainfall, the decreasing effect of sediment on DRP and PP declined somewhat. The effects of sediment addition can be attributed partly to increased salt concentrations in the sediment, which have a short-term effect on P mobilization, but mostly to increased concentrations of Al and Fe (hydr)oxides, increasing long-term P sorption capacity. Adding CW sediment at a rate of up to 5% of surface soil volume to soils could provide an alternative to chemical treatment (e.g., with metal salts) for immobilizing P in small, high-risk P leaching areas, such as around drinking troughs in pastures.

  18. Can constructed wetlands reduce the diffuse phosphorus loads to eutrophic water in cold temperate regions?

    PubMed

    Braskerud, B C; Tonderski, K S; Wedding, B; Bakke, R; Blankenberg, A-G B; Ulén, B; Koskiaho, J

    2005-01-01

    Construction of wetlands is a possible supplement to best management practices (BMP) at the field level to mitigate phosphorus (P) pollution from agricultural areas. In this paper, annual results from 17 intensively studied wetlands in the cold temperate or boreal climatic zone are reported and analyzed. Surface areas varied from 0.007 to 8.7% of the catchment area. The average total phosphorus (TP) retention varied from 1 to 88%, and the dissolved reactive phosphorus (DRP) retention from -19 to 89%. Retention varied substantially from site to site, indicating the existence of site-specific factors in the catchment and wetlands that influenced the P removal. Factors important for P retention in wetlands were evaluated through multiple statistical analyses by dividing P into two fractions: particulate phosphorus (PP) and DRP. Both relative (%) PP and DRP retention increased with wetland surface area. However, PP retention was not as sensitive as DRP in terms of wetland size and retention: specific PP retention (gram P retention per m(2) and year) decreased as wetland area (A(w)) increased, suggesting the existence of a site-specific optimal wetland to catchment area (A(c)) ratio. Particulate P retention decreased with increasing DRP to TP ratio, while the opposite was found for DRP. Dissolved reactive P retention was higher in new than in old wetlands, while increasing age did not influence PP retention negatively. Effective BMP in the catchment is important to keep the P loss low, because the outlet concentration of P from wetlands is often positively correlated to the input concentration. However, wetlands act as the last buffer in a catchment, since the retention often increases as the P concentration in streams increases.

  19. Transport and transformation of de-icing urea from airport runways in a constructed wetland system.

    PubMed

    Thorén, A K; Legrand, C; Herrmann, J

    2003-01-01

    Urea, NH2-CO-NH2, is used as a de-icing agent at Kalmar Airport, southeast Sweden. During 1998-2001, urea contributed on average 30% of the yearly nitrogen (N) transport of 41,000 kg via Törnebybäcken stream to the coastal zone of the Baltic Sea. In order to reduce stream transport of N from airport, agricultural and other diffuse sources, a wetland was constructed in 1996. Annual wetland retention of total-N varied in the range of 2,500-8,100 kg (6-36% of influent) during 1998-2001, according to mass balances calculated from monthly sampling. During airport de-icing, January-March 2001,660 kg urea-N out of 2,600 kg applied urea-N reached the wetland according to daily sampling. This indicated that 75% of the urea was transformed before entering the wetland. Urea was found to be only a minor part (8%) of total-N in the wetland influent. Calculations of cumulative urea-N loads at the wetland inlet and outlet respectively, showed a significant urea transformation during February 2001 with approximately 40% of the incoming urea-N being transformed in the wetland system. These results show that significant amounts of urea can be transformed in a wetland system at air temperatures around 0 degree C.

  20. Efficiency of Constructed Wetland Vegetated with Cyperus alternifolius Applied for Municipal Wastewater Treatment

    PubMed Central

    Ebrahimi, Asghar; Taheri, Ensiyeh; Ehrampoush, Mohammad Hassan; Nasiri, Sara; Jalali, Fatemeh; Soltani, Rahele; Fatehizadeh, Ali

    2013-01-01

    The treatment of municipal wastewater from Yazd city (center of Iran) by constructed wetland vegetated with Cyperus alternifolius was assessed. Two identical wetlands with a total working volume of 60 L and 10 cm sandy layer at the bottom were used. First wetland (W1) was control and had no Cyperus alternifolius plant. Second wetland (W2) had 100 Cyperus alternifolius shrubs with 40 cm height. Influent wastewater was provided from Yazd's septic tanks effluents and after a 4-day retention time in wetlands, reactors effluent was sampled for parameters analysis. Results show that chemical oxygen demand (COD), NO3 −–N, NH4 +–N, and PO4 −3–P in W1 were reduced to 72%, 88%, 32%, and 0.8%, and in W2, these parameters were removed in values of 83%, 81%, 47%, and 10%, respectively. In both wetlands, the highest and lowest removal efficiencies were related to COD and phosphorus, respectively. Also, the removed phosphorus can be released to stream when the soil saturated or influent phosphorus decreased and when the plant died. After a 4-day-retention time, the W2 wetland showed a statistically significantly lower COD and NH4 +–N in comparison with W2 wetland. PMID:24027589

  1. Efficiency of constructed wetland vegetated with Cyperus alternifolius applied for municipal wastewater treatment.

    PubMed

    Ebrahimi, Asghar; Taheri, Ensiyeh; Ehrampoush, Mohammad Hassan; Nasiri, Sara; Jalali, Fatemeh; Soltani, Rahele; Fatehizadeh, Ali

    2013-01-01

    The treatment of municipal wastewater from Yazd city (center of Iran) by constructed wetland vegetated with Cyperus alternifolius was assessed. Two identical wetlands with a total working volume of 60 L and 10 cm sandy layer at the bottom were used. First wetland (W1) was control and had no Cyperus alternifolius plant. Second wetland (W2) had 100 Cyperus alternifolius shrubs with 40 cm height. Influent wastewater was provided from Yazd's septic tanks effluents and after a 4-day retention time in wetlands, reactors effluent was sampled for parameters analysis. Results show that chemical oxygen demand (COD), NO3 (-)-N, NH4 (+)-N, and PO4 (-3)-P in W1 were reduced to 72%, 88%, 32%, and 0.8%, and in W2, these parameters were removed in values of 83%, 81%, 47%, and 10%, respectively. In both wetlands, the highest and lowest removal efficiencies were related to COD and phosphorus, respectively. Also, the removed phosphorus can be released to stream when the soil saturated or influent phosphorus decreased and when the plant died. After a 4-day-retention time, the W2 wetland showed a statistically significantly lower COD and NH4 (+)-N in comparison with W2 wetland.

  2. Growth and contaminant removal effect of several plants in constructed wetlands.

    PubMed

    Cheng, Xiu-Yun; Liang, Ming-Qiu; Chen, Wen-Yin; Liu, Xu-Cheng; Chen, Zhang-He

    2009-03-01

    The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands. Four species were studied in the small-scale mono-cultured constructed wetlands, which were fed with domestic wastewater. Plant growth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal. Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants.

  3. Comparison of Constructed Wetland Mesocosms Designed for Treatment of Copper-Contaminated Wastewater

    SciTech Connect

    Gladden, J.B.

    2001-02-15

    This study compared the performance of two constructed wetland mesocosms used to model a full-scale wetland system designed for treatment of copper-contaminated wastewater. One mesocosm (designated site-specific) was built near the construction site of the full-scale wetland using on-site soil, commercially available vegetation [Scirpus californicus (C.A. Meyer) Steud.], and water from the targeted wastestream. A second mesocosm (designated generic) was constructed at Clemson University using local soil, cultured S. californicus, and local municipal water amended with CuSO{sub 4}. Performance objectives were to achieve 22 m g/L total copper and no toxicity (Ceriodaphnia dubia Richard, 7-d/static/ renewal) in wetland outflows. Total inflow copper to the site-specific and generic mesocosms ranged from non-detect to 87 {micro} g/L and from 27 to 68 {micro} g/L, respectively. Overall total copper removal was 40% ({+-}33) for the site-specific mesocosm and 73% ({+-}14) for the generic mesocosm. In seven of nine monthly toxicity tests, C. dubia reproduction was significantly decreased ({alpha} = 0.05) in outflow of the site-specific mesocosm. No outflow toxicity was observed for the generic mesocosm. Although performance of the two mesocosms differed, both studies contributed to full-scale design by highlighting critical aspects of wetland function and augmenting operation and maintenance plans, enhancing overall constructed wetland design.

  4. The use of Bassia indica for salt phytoremediation in constructed wetlands.

    PubMed

    Shelef, Oren; Gross, Amit; Rachmilevitch, Shimon

    2012-09-01

    The treatment and reuse of wastewater in constructed wetlands offers a low-cost, environmentally-friendly alternative for common engineered systems. Salinity in treated wastewater is often increased, especially in arid and semi-arid areas, and may harm crops irrigated from wetlands. We have strong evidence that halophyte plants are able to reduce the salinity of wastewater by accumulating salts in their tissues. Bassia indica is an annual halophyte with unique adaptations for salt tolerance. We performed three experiments to evaluate the capability of B. indica for salt phytoremediation as follows: a hydroponic system with mixed salt solutions, a recirculated vertical flow constructed wetland (RVFCW) with domestic wastewater, and a vertical flow constructed wetland (VFCW) for treating goat farm effluents. B. Indica plants developed successfully in all three systems and reduced the effluent salinity by 20-60% in comparison with unplanted systems or systems planted with other wetland plants. Salinity reduction was attributed to the accumulation of salts, mainly Na and K, in the leaves. Our experiments were carried out on an operative scale, suggesting a novel treatment for green desalination in constructed wetlands by salt phytoremediation in desert regions and other ecosystems.

  5. Impact of flood damage on pollutant removal efficiencies of a subtropical urban constructed wetland.

    PubMed

    Ko, Chun-Han; Chang, Fang-Chih; Lee, Tsai-Ming; Chen, Pen-Yuan; Chen, Hsin-Hsiung; Hsieh, Hwey-Lien; Guan, Chung-Yu

    2010-09-15

    Typhoons and hurricanes in subtropical/tropical regions can induce significant environmental changes (e.g., mass flooding and inundations). However, the damage to the pollutant removal efficiencies of constructed wetlands brought about by these natural disturbances has been neglected in major studies conducted in temperate climates. Therefore, this study compares the pollutant removal performance of a constructed wetland in the Danshui River Basin, before and after the system was inundated with flooding from Typhoon Krosa in 2007. The pollutant removal performance of the free water surface (FWS) constructed wetland was investigated monthly from September 2006 to April 2008. Results of the study demonstrated that this FWS wetland effectively removed 64.3% BOD, 98.9% NH(4)-N, and 39.5% Total-P before Typhoon Krosa. However, the extensive flooding caused by Typhoon Krosa swept over most of the aboveground plant community and deposited the sediment onto the bottom of each compartment. Subsequently, reduced pollutant removal efficiencies were observed. Only 37.7% BOD, 35.1% NH(4)-N, and 31.8% Total-P were removed after this event, although the flow regime was immediately restored. Comparing the water quality data for the FWS wetland before and after Typhoon Krosa revealed the immediate, quantitative damage to the pollutant removal performance caused by the typhoon's inundation. Consequently, a high-flow bypass and additional preventive measures would protect any constructed wetland in areas subject to typhoons. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Nitrogen removal and greenhouse gas emissions from constructed wetlands receiving tile drainage water.

    PubMed

    Groh, Tyler A; Gentry, Lowell E; David, Mark B

    2015-05-01

    Loss of nitrate from agricultural lands to surface waters is an important issue, especially in areas that are extensively tile drained. To reduce these losses, a wide range of in-field and edge-of-field practices have been proposed, including constructed wetlands. We re-evaluated constructed wetlands established in 1994 that were previously studied for their effectiveness in removing nitrate from tile drainage water. Along with this re-evaluation, we measured the production and flux of greenhouse gases (GHGs) (CO, NO, and CH). The tile inlets and outlets of two wetlands were monitored for flow and N during the 2012 and 2013 water years. In addition, seepage rates of water and nitrate under the berm and through the riparian buffer strip were measured. Greenhouse gas emissions from the wetlands were measured using floating chambers (inundated fluxes) or static chambers (terrestrial fluxes). During this 2-yr study, the wetlands removed 56% of the total inlet nitrate load, likely through denitrification in the wetland. Some additional removal of nitrate occurred in seepage water by the riparian buffer strip along each berm (6.1% of the total inlet load, for a total nitrate removal of 62%). The dominant GHG emitted from the wetlands was CO, which represented 75 and 96% of the total GHG emissions during the two water years. The flux of NO contributed between 3.7 and 13% of the total cumulative GHG flux. Emissions of NO were 3.2 and 1.3% of the total nitrate removed from wetlands A and B, respectively. These wetlands continue to remove nitrate at rates similar to those measured after construction, with relatively little GHG gas loss. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  7. Nitrogen and COD Removal from Septic Tank Wastewater in Subsurface Flow Constructed Wetlands: Plants Effects.

    PubMed

    Collison, R S; Grismer, M E

    2015-11-01

    We evaluated subsurface flow (SSF) constructed wetland treatment performance with respect to organics (COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) wastewater as affected by the presence of plants, substrate "rock" cation exchange capacity (CEC), laboratory versus field conditions and use of synthetic as compared to actual domestic wastewater. This article considers the effects of plants on constructed wetland treatment in the field. Each constructed wetland system was comprised of two beds (2.6 m long by 0.28 m wide and deep filled with ~18 mm crushed lava rock) separated by an aeration tank connected in series. The lava rock had a porosity of ~47% and a CEC of 4 meq/100 gm. One pair of constructed wetland systems was planted with cattails in May 2008, while an adjacent pair of systems remained un-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each constructed wetland system and effluent samples were regularly collected and tested for COD and nitrogen species during four time periods spanning November 2008 through June 2009. These effluent concentrations were tested for statistical differences at the 95% level for individual time periods as well as the overall 6-month period. Organics removal from domestic wastewater was 78.8% and 76.1% in the planted and un-planted constructed wetland systems, respectively, while ammonium removal was 94.5% and 90.2%, respectively. Similarly, organics removal from the synthetic wastewater of equivalent strength was 88.8% and 90.1% for planted and un-planted constructed wetland systems, respectively, while ammonium removal was 96.9% and 97.3%, respectively.

  8. Spatial pattern analysis for water quality in free-surface constructed wetland.

    PubMed

    Mohammadpour, Reza; Shaharuddin, Syafiq; Chang, Chun Kiat; Zakaria, Nor Azazi; Ab Ghani, Aminuddin

    2014-01-01

    Free-surface constructed wetlands are known as a low-energy green technique to highly decrease a wide range of pollutants in wastewater and stormwater before discharge into natural water. In this study, two spatial analyses, principal factor analysis and hierarchical cluster analysis (HACA), were employed to interpret the effect of wetland on the water quality variables (WQVs) and to classify the wetland into groups with similar characteristics. Eleven WQVs were collected at the 17 sampling stations twice a month for 13 months. All sampling stations were classified by HACA into three clusters, with high, moderate, and low pollution areas. To improve the water quality, the performance of Cluster-III (micropool) is more significant than Cluster-I and Cluster-II. Implications of this study include potential savings of time and cost for long-term data monitoring purposes in the free-constructed wetland.

  9. Long-term purification efficiency of a wetland constructed to treat runoff from peat extraction.

    PubMed

    Karjalainen, Satu M; Heikkinen, Kaisa; Ihme, Raimo; Kløve, Bjørn

    2016-01-01

    Peat extraction increases the phosphorus, nitrogen, organic matter, suspended solids, and iron concentrations in runoff, resulting in negative effects on downstream water bodies. Wetlands are commonly used as natural cost-effective solutions to mitigate these negative effects. This study analyzed changes in the quality of runoff water from peat extraction areas and the long-term efficiency of constructed wetlands. The results indicate that the quality of runoff water changed after the initial drainage and during peat extraction. Nitrogen leached at high concentrations in the early stages of peat extraction following drainage, whereas the leaching of iron and phosphorus increased after peat extraction from deeper layers. Comparison of water quality and impurities retained immediately after treatment wetland construction and 14 years later showed that the treatment wetland remained functional, with good retention capacity, over a long period.

  10. Study on treatment of aquaculture wastewater using a hybrid constructed wetland

    NASA Astrophysics Data System (ADS)

    Hu, Jinzhao; Hu, Rui; Qi, Dan; Lu, Xujie

    2017-04-01

    This paper reported the pollutant removal performances of a hybrid wetland system for the treatment of aquaculture wastewater. The system consisted of two treatment stages: a subsurface vertical flow (VF) wetland, followed by a horizontal flow (HF). The aquaculture wastewater with the different concentrations such as eutrophy and mesotrophy was treated using hybrid constructed wetland. The experimental results showed that the removal efficiencies of eutrophy aquaculture wastewater achieved 56%, 71%, 73% for nitrite, phosphate and nitrate, respectively. At the same conditions, it can be found that the removal efficiencies of mesotrophy aquaculture wastewater achieved 39%, 74%, 73% for nitrite, phosphate and nitrate, respectively.

  11. A bench-scale constructed wetland as a model to characterize benzene biodegradation processes in freshwater wetlands.

    PubMed

    Rakoczy, Jana; Remy, Benjamin; Vogt, Carsten; Richnow, Hans H

    2011-12-01

    In wetlands, a variety of biotic and abiotic processes can contribute to the removal of organic substances. Here, we used compound-specific isotope analysis (CSIA), hydrogeochemical parameters and detection of functional genes to characterize in situ biodegradation of benzene in a model constructed wetland over a period of 370 days. Despite low dissolved oxygen concentrations (<30 μM), the oxidation of ammonium to nitrate and the complete oxidation of ferrous iron pointed to a dominance of aerobic processes, suggesting efficient oxygen transfer into the sediment zone by plants. As benzene removal became highly efficient after day 231 (>98% removal), we applied CSIA to study in situ benzene degradation by indigenous microbes. Combining carbon and hydrogen isotope signatures by two-dimensional stable isotope analysis revealed that benzene was degraded aerobically, mainly via the monohydroxylation pathway. This was additionally supported by the detection of the BTEX monooxygenase gene tmoA in sediment and root samples. Calculating the extent of biodegradation from the isotope signatures demonstrated that at least 85% of benzene was degraded by this pathway and thus, only a small fraction was removed abiotically. This study shows that model wetlands can contribute to an understanding of biodegradation processes in floodplains or natural wetland systems.

  12. Establishment of vegetation in constructed wetlands using biosolids and quarry fines

    SciTech Connect

    Danehy, T.P.; Zick, R.; Brenner, F.; Chmielewski, J.; Dunn, M.H.; Cooper, D.C.

    1999-07-01

    A common problem with constructing wetlands on abandoned mine sties is the lack of adequate soil needed to establish vegetation. One component of a full-scale passive treatment system built at Jennings Environmental Education Center in Brady Township, Butler County, PA addressed this issue through the development of a field trial to find an inexpensive alternative substrate for wetland plants. A simple soil recipe was followed which called for the mixing of an inorganic material with a nutrient-rich organic material. The inorganic constituent used was silt-size pond cleanings from a sand and gravel operation. The organic material used was a composted product made from exceptional-quality biosolids. Both soil components were obtained from local sources (less than 16 kilometers (12 miles) from the site) and mixed on site with a Caterpillar 963 track loader. The soil was used to construct a channel wetland 3 meters (10 feet) wide by 61 meters (200 feet) long. A seed mixture which contained 24 different wetland plant species native to western Pennsylvania was added to the substrate prior to releasing the water from the vertical flow system into the wetland. After one year, the vegetation was studied to determine the percent cover and species composition in order to document the effectiveness of this method of wetland construction. The preliminary results of this study indicate that this is an effective means to establish and sustain wetland vegetation. The addition of a fabricated substrate consisting of composted biosolids and silt can be a very effective method to establish dense and diverse vegetation in a constructed wetland.

  13. Emergy-based evaluation of system sustainability and ecosystem value of a large-scale constructed wetland in North China.

    PubMed

    Zhang, Yiran; Liu, Jian; Zhang, Jian; Wang, Renqing

    2013-07-01

    Constructed wetland has been widely adopted to deal with degraded natural wetlands and water bodies; thus, more attention should be focused on ecological-economic sustainability and ecological efficiency of these projects for long-term success. Emergy accounting was conducted to investigate the energy and resource flows in constructed wetlands during the restoration process. Emergy-based indexes were adopted to evaluate the sustainability of a pilot large-scale constructed wetland in a large wetland restoration project in North China, carried out to enhance the river water quality and offset the degradation of natural wetland. Emergy and emdollar values for ecosystem services and natural capital were also calculated. The results showed that when outflow was considered as the product, the studied large-scale constructed wetland was more self-supporting and could be operated with lesser financial investment, although the waste treatment efficiency and the sustainability index were lower than conventional small-scale treatment constructed wetlands. Compared with natural wetlands, more visits from tourists and lesser financial investment coming in as feedback into the wetland would reduce system environment loading and promote system self-support ability, ultimately generating sustainability. In addition, the studied large-scale constructed wetland can effectively simulate energy and resource flows of natural wetland ecosystem and contribute a roughly equal value of ecosystem services in term of gross primary production. The studied large-scale constructed wetland can successfully achieve ecosystem functions as replacement for natural wetland and hasten the restoration process, although the restoration effectiveness of ecosystem structures in terms of living biomass and water using emergy-value accounting is still inconclusive.

  14. Removal of pathogenic and indicator microorganisms by a constructed wetland receiving untreated domestic wastewater.

    PubMed

    Quiñónez-Díaz, M J; Karpiscak, M M; Ellman, E D; Gerba, C P

    2001-01-01

    Wetlands containing floating, emergent and submergent aquatic plants, and other water-tolerant species have been found to economically provide a mechanism of enhancing the quality of domestic wastewater. The use of constructed wetlands for the removal of indicator bacteria (total and fecal coliforms), coliphages, protozoan parasites (Giardia and Cryptosporidium) and enteric viruses was investigated. A pilot scale constructed wetland consisting of two cells, one planted with bulrush and the other unplanted bare sand, were used to compare their efficiency in removing pathogens from raw sewage. Overall more than 90 percent of all microorganisms studied were removed by either of the two systems with a 1 to 2 day retention time. Removal of all mentioned microorganisms was greater from the surface flow in the unplanted cell than in the planted cell, except for Giardia and Cryptosporidium, although the differences were not statistically significant. Enteric viruses, coliphages and indicator bacteria were found to penetrate 2 m below the surface, although concentrations were reduced by greater than 99 percent in both cells. Less virus penetration into the sand occurred in the planted wetland versus the unplanted wetland. Water temperature was found to be the most important factor in the removal of enteric bacteria and viruses, while turbidity reduction was related to Giardia removal. These results demonstrate that significant reductions of pathogenic microorganisms can occur in constructed wetlands receiving untreated domestic wastewater with only a 1-2 day retention time.

  15. 'Halophyte filters': the potential of constructed wetlands for application in saline aquaculture.

    PubMed

    De Lange, H J; Paulissen, M P C P; Slim, P A

    2013-01-01

    World consumption of seafood continues to rise, but the seas and oceans are already over-exploited. Land-based (saline) aquaculture may offer a sustainable way to meet the growing demand for fish and shellfish. A major problem of aquaculture is nutrient waste, as most of the nutrients added through feed are released into the environment in dissolved form. Wetlands are nature's water purifiers. Constructed wetlands are commonly used to treat contaminated freshwater effluent. Experience with saline systems is more limited. This paper explores the potential of constructed saline wetlands for treating the nutrient-rich discharge from land-based saline aquaculture systems. The primary function of constructed wetlands is water purification, but other ancillary benefits can also be incorporated into treatment wetland designs. Marsh vegetation enhances landscape beauty and plant diversity, and wetlands may offer habitat for fauna and recreational areas. Various approaches can be taken in utilizing plants (halophytes, macro-algae, micro-algae) in the treatment of saline aquaculture effluent. Their strengths and weaknesses are reviewed here, and a conceptual framework is presented that takes into account economic and ecological benefits as well as spatial constraints. Use of the framework is demonstrated for assessing various saline aquaculture systems in the southwestern delta region of the Netherlands.

  16. [Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

    PubMed

    Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

    2014-02-01

    The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

  17. Environmental effect of constructed wetland as biofuel production system

    NASA Astrophysics Data System (ADS)

    Liu, Dong

    2017-04-01

    Being as a renewable energy, biofuel has attracted worldwide attention. Clean biofuel production is an effective way to mitigate global climate change and energy crisis. Biofuel may offer a promising alternative to fossil fuels, but serious concerns arise about the adverse greenhouse gas consequences from using nitrogen fertilizers. Waste-nitrogen recycling is an attractive idea. Here we advocate a win-win approach to biofuel production which takes advantage of excessive nitrogen in domestic wastewater treated via constructed wetland (CW) in China. This study will carry on environmental effect analysis of CW as a biomass generation system through field surveys and controllable simulated experiments. This study intends to evaluate net energy balance, net greenhouse effect potential and ecosystem service of CW as biomass generation system, and make comparation with traditional wastewater treatment plant and other biofuel production systems. This study can provide a innovation mode in order to solve the dilemma between energy crops competed crops on production land and excessive nitrogen fertilizer of our traditional energy plant production. Data both from our experimental CWs in China and other researches on comparable CWs worldwide showed that the biomass energy yield of CWs can reach 182.3 GJ ha-1 yr-1, which was two to eight times higher than current biofuel-production systems. Energy output from CW was ˜137% greater than energy input for biofuel production. If CWs are designed with specific goal of biofuel production, biofuel production can be greatly enhanced through the optimization of N supply, hydraulic structures, and species selection in CWs. Assuming that 2.0 Tg (1 Tg = 1012 g) waste nitrogen contained in domestic wastewater is treated by CWs, biofuel production can account for 1.2% of national gasoline consumption in China. The proportion would increase to 6.7% if extra nitrogen (9.5 Tg) from industrial wastewater and agricultural runoff was included

  18. Removal of antibiotics from urban wastewater by constructed wetland optimization.

    PubMed

    Hijosa-Valsero, María; Fink, Guido; Schlüsener, Michael P; Sidrach-Cardona, Ricardo; Martín-Villacorta, Javier; Ternes, Thomas; Bécares, Eloy

    2011-04-01

    Seven mesocosm-scale constructed wetlands (CWs), differing in their design characteristics, were set up in the open air to assess their efficiency to remove antibiotics from urban raw wastewater. A conventional wastewater treatment plant (WWTP) was simultaneously monitored. The experiment took place in autumn. An analytical methodology including HPLC-MS/MS was developed to measure antibiotic concentrations in the soluble water fraction, in the suspended solids fraction and in the WWTP sludge. Considering the soluble water fraction, the only easily eliminated antibiotics in the WWTP were doxycycline (61±38%) and sulfamethoxazole (60±26%). All the studied types of CWs were efficient for the removal of sulfamethoxazole (59±30-87±41%), as found in the WWTP, and, in addition, they removed trimethoprim (65±21-96±29%). The elimination of other antibiotics in CWs was limited by the specific system-configuration: amoxicillin (45±15%) was only eliminated by a free-water (FW) subsurface flow (SSF) CW planted with Typha angustifolia; doxycycline was removed in FW systems planted with T. angustifolia (65±34-75±40%), in a Phragmites australis-floating macrophytes system (62±31%) and in conventional horizontal SSF-systems (71±39%); clarithromycin was partially eliminated by an unplanted FW-SSF system (50±18%); erythromycin could only be removed by a P. australis-horizontal SSF system (64±30%); and ampicillin was eliminated by a T. angustifolia-floating macrophytes system (29±4%). Lincomycin was not removed by any of the systems (WWTP or CWs). The presence or absence of plants, the vegetal species (T. angustifolia or P. australis), the flow type and the CW design characteristics regulated the specific removal mechanisms. Therefore, CWs are not an overall solution to remove antibiotics from urban wastewater during cold seasons. However, more studies are needed to assess their ability in warmer periods and to determine the behaviour of full-scale systems. Copyright

  19. Effects of a constructed wetland and pond system upon shallow groundwater quality

    Treesearch

    Ying Ouyang

    2013-01-01

    Constructed wetland (CW) and constructed pond (CP) are commonly utilized for removal of excess nutrients and certain pollutants from stormwater. This study characterized shallow groundwater quality for pre- and post-CW and CP system conditions using data from monitoring wells. Results showed that the average concentrations of groundwater phosphorus (P) decreased from...

  20. Enhanced P, N and C removal from domestic wastewater using constructed wetland employing construction solid waste (CSW) as main substrate.

    PubMed

    Yang, Y; Wang, Z M; Liu, C; Guo, X C

    2012-01-01

    Construction solid waste (CSW), an inescapable by-product of the construction and demolition process, was used as main substrate in a four-stage vertical subsurface flow constructed wetland system to improve phosphorus P removal from domestic wastewater. A 'tidal flow' operation was also employed in the treatment system. Under a hydraulic loading rate (HLR) of 0.76 m3/m2 d for 1st and 3rd stage and HLR of 0.04 m3/m2 d for 2nd and 4th stage of the constructed wetland system respectively and tidal flow operation strategy, average removal efficiencies of 99.4% for P, 95.4% for ammoniacal-nitrogen, 56.5% for total nitrogen and 84.5% for total chemical oxygen demand were achieved during the operation period. The CSW-based constructed wetland system presents excellent P removal performance. The adoption of tidal flow strategy creates the aerobic/anoxic condition intermittently in the treatment system. This can achieve better oxygen transfer and hence lead to more complete nitrification and organic matter removal and enhanced denitrification. Overall, the CSW-based tidal flow constructed wetland system holds great promise for enabling high rate removal of P, ammoniacal-nitrogen and organic matter from domestic wastewater, and transforms CSW from a waste into a useful material.

  1. An assessment of potential hydrologic and ecologic impacts of constructing mitigation wetlands, Rifle, Colorado, UMTRA project sites

    SciTech Connect

    1995-04-01

    This-assessment examines the consequences and risks that could result from the proposed construction of mitigation wetlands at the New and Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) Project sites near Rifle, Colorado. Remediation of surface contamination at those sites is now under way. Preexisting wetlands at or near the Old and New Rifle sites have been cleaned up, resulting in the loss of 0.7 and 10.5 wetland acres (ac) (0.28 and 4.2 hectares [ha]) respectively. Another 9.9 ac (4.0 ha) of wetlands are in the area of windblown contamination west of the New Rifle site. The US Army Corps of Engineers (USACE) has jurisdiction over the remediated wetlands. Before remedial action began, and before any wetlands were eliminated, the USACE issued a Section 404 Permit that included a mitigation plan for the wetlands to be lost. The mitigation plan calls for 34.2 ac (1 3.8 ha) of wetlands to be constructed at the south end and to the west of the New Rifle site. The mitigation wetlands would be constructed over and in the contaminated alluvial aquifer at the New Rifle site. As a result of the hydrologic characteristics of this aquifer, contaminated ground water would be expected to enter the environment through the proposed wetlands. A preliminary assessment was therefore required to assess any potential ecological risks associated with constructing the mitigation wetlands at the proposed location.

  2. Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.

    PubMed

    Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

    2009-09-30

    To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes.

  3. Ceriodaphnia and Chironomus in situ toxicity tests assessing the wastewater treatment efficacy of constructed wetlands

    SciTech Connect

    Barjaktarovic, L.; Nix, P.; Gulley, J.

    1995-12-31

    In situ toxicity tests were designed for Ceriodaphnia dubia and Chironomus tentans as part of a larger study designed to assess the effectiveness of constructed wetlands for the treatment of wastewater produced by oil production at Suncor OSG. The artificial wetlands were 50m long by 3m wide, with three replicates of the control and the treatment. Each wetland had four sample sites equidistant along its length, creating a gradient of treatment from site A being the most toxic to site D being the least toxic. Each test was conducted twice during the summer of 1994. Both the Ceriodaphnia and Chironomus test cages were a flow through design to allow for maximal exposure to the water within the wetlands. Mortality and reproduction were used as endpoints for Ceriodaphnia, whereas mortality and growth were used as endpoints for the Chironomus test. Test durations were fifteen and ten days respectively. Chironomus had very high mortality along the entire wetlands whereas Ceriodaphnia survival and fecundity increased along the length of the treatment wetlands. Both organisms had low mortality and high growth/fecundity in the control wetlands.

  4. Effects of acidification on metal accumulation by aquatic plants and invertebrates. 1. Constructed wetlands

    SciTech Connect

    Albers, P.H.; Camardese, M.B. . Patuxent Wildlife Research Center)

    1993-06-01

    Compared were concentrations of Al,Cd,Ca,Cu,Fe,Hg,Pb,Mg,Mn,Ni,P, and Zn in water, plants and aquatic insects of three acidified (pH [approximately] 5.0) and three nonacidified (pH [approximately] 6.5) constructed wetlands. Concentrations of Zn in water and bur-reed (Sparganium americanum) were higher in acidified wetlands than in nonacidified wetlands. Floating nonrooted plants contained mean concentrations of Fe, Mg, and Mn that were higher than recommended maximum levels for poultry feed. The mean concentrations of all metals in insects were below recommended maximum levels for poultry feed and below levels that cause toxic effects in wild birds. Smaller than expected increases of metal concentrations in the water of acidified wetlands were probably due to limited mobilization of metals from the sediments and insignificant changes in sedimentation of aqueous metals. Calcium was lower in acidified than in nonacidified wetland water, but the Ca content of insects and bur-reed was not lower. Low concentrations of Ca in aquatic insects from both groups of wetlands indicated that calcium-rich crustaceans and mollusks are probably important to female waterfowl and their young during the spring, when invertebrates make up the majority of the diet. Although toxic effects from metal ingestion seem to be unlikely consequences of wetland acidification, the adverse effect of low pH on the occurrence of crustaceans and mollusks could threatened egg production and development of young.

  5. Phosphorus removal in a surface-flow constructed wetland treating agricultural runoff.

    PubMed

    Beutel, Marc W; Morgan, Matthew R; Erlenmeyer, Jonathan J; Brouillard, Elaine S

    2014-05-01

    Agricultural runoff is a leading source of phosphorus (P) pollution to lakes and streams. The objective of this study was to evaluate P removal dynamics in a constructed treatment wetland (CTW) treating agricultural irrigation return flows. The CTW included a sedimentation basin (SB) followed by two surface-flow wetlands in parallel. Typical retention times and total P (TP) loading were 1.4 d and 50 to 110 g m yr P, respectively, for the SB and 5 to 6 d and 4 to 10 g m yr P, respectively, for wetlands. On the basis of this multiyear study, concentration removal efficiency in the SB averaged 21% for TP and 32% for reactive phosphorus (RP). Concentration removal efficiency in wetlands averaged 37 and 43% for TP and 22 and 33% for RP. Areal first-order removal rates for TP averaged 22 and 31 m yr in wetlands. Total P removal in wetlands exhibited a strong seasonal pattern, with minimum removal in the summer when high temperatures likely enhanced P release from decaying plant biomass. The performance of the CTW was stochastic, with removal unpredictably poorer in some years in part as a result of muskrat bioturbation and plant harvesting. In years before muskrat impacts, concentration removal efficiencies in wetlands were 50% for TP and 65% for RP. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Wetlands.

    ERIC Educational Resources Information Center

    Nelson, Patricia L.

    1986-01-01

    Suggests studying New York's wetlands, both in the classroom and in the field, to illustrate ecological concepts of diversity, succession, and adaptation and to learn about their importance in controlling flooding, erosion, and pollution. (NEC)

  7. Wetlands.

    ERIC Educational Resources Information Center

    Nelson, Patricia L.

    1986-01-01

    Suggests studying New York's wetlands, both in the classroom and in the field, to illustrate ecological concepts of diversity, succession, and adaptation and to learn about their importance in controlling flooding, erosion, and pollution. (NEC)

  8. Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Optimization of wetland substrates and hydraulic loading.

    PubMed

    Chen, Jun; Wei, Xiao-Dong; Liu, You-Sheng; Ying, Guang-Guo; Liu, Shuang-Shuang; He, Liang-Ying; Su, Hao-Chang; Hu, Li-Xin; Chen, Fan-Rong; Yang, Yong-Qiang

    2016-09-15

    This study aimed to assess removal potential of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale horizontal subsurface-flow constructed wetlands (CWs) planted Cyperus alternifolius L. with different design parameters. Twelve CWs with three hydraulic loading rates (HLR 10, 20 and 30cm/day) and four substrates (oyster shell, zeolite, medical stone and ceramic) were set up in order to select the best optimized wetland. The result showed that 7 target antibiotics compounds including erythromycin-H2O, lincomycin, monensin, ofloxacin, sulfamerazine, sulfamethazine and novobiocin were detected, and all selected 18 genes (three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), three quinolone resistance genes (qnrB, qnrD and qnrS) and four chloramphenicol resistance genes (cmlA, fexA, fexB and floR)) and two integrase genes (int1 and int2) were positively detected in the domestic wastewaters. The aqueous removal rates of the total antibiotics ranged from17.9 to 98.5%, while those for the total ARGs varied between 50.0 and 85.8% by the mesocosm-scale CWs. After considering their aqueous removal rates in combination with their mass removals, the CW with zeolite as the substrate and HLR of 20cm/day was selected as the best choice. Combined chemical and biological analyses indicate that both microbial degradation and physical sorption processes were responsible for the fate of antibiotics and ARGs in the wetlands. The findings from this study suggest constructed wetlands could be a promising technology for the removal of emerging contaminants such as antibiotics and ARGs in domestic wastewater. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation.

    PubMed

    Tatoulis, Triantafyllos; Stefanakis, Alexandros; Frontistis, Zacharias; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Mantzavinos, Dionissios; Vayenas, Dimitrios V

    2017-01-01

    The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost. Previously, biological filters were combined with electrooxidation to treat table olive washing water. Although this combination was successful in reducing pollutant loads, its cost could be further reduced. Constructed wetlands could be an eligible treatment method for integrated table olive washing water treatment as they have proved tolerant to high organic matter and phenol loads. Two pilot-scale horizontal subsurface constructed wetlands, one planted and one unplanted, were combined with a biological filter and electrooxidation over a boron-doped diamond anode to treat table olive washing water. In the biological filter inlet, chemical oxygen demand (COD) concentrations ranged from 5500 to 15,000 mg/L, while mean COD influent concentration in the constructed wetlands was 2800 mg/L. The wetlands proved to be an efficient intermediate treatment stage, since COD removal levels for the planted unit reached 99 % (mean 70 %), while the unplanted unit presented removal rates of around 65 %. Moreover, the concentration of phenols in the effluent was typically below 100 mg/L. The integrated trickling filter-constructed wetland-electrooxidation treatment system examined here could mineralize and decolorize table olive washing water and fully remove its phenolic content.

  10. Evaluation of a constructed wetland treatment system specifically designed to decrease bioavailable copper in a wastestream.

    PubMed

    Murray-Gulde, Cynthia L; Bearr, Jonathan; Rodgers, John H

    2005-05-01

    A specifically designed constructed wetland decreased copper concentrations in a wastestream to 22 microg Cu/L and eliminated associated toxicity. Metal toxicity is a function of both concentration and form. This research measured copper partitioning to ligands within the wetland and observed changes in copper form with regard to bioavailability. Average monthly copper concentrations in the constructed wetland treatment system ranged from 10 to 47 microg/L in the upstream (i.e., inflow to the constructed wetland prior to the retention basin) and from non-detection to 11 microg/L in the downstream (i.e., outflow to the receiving stream). On average, 78% total-recoverable, 85% acid-soluble, and 83% soluble copper were removed from inflow to outflow of this constructed wetland; however, total recoverable and acid-soluble copper measurements were not useful indicators of bioavailable copper. Survival of Ceriodaphnia dubia increased from an average of 2% survival in the inflow to 96% in the outflow and reproduction increased from an average of 8 to 24 neonates/female, respectively. Soluble copper is a more accurate predictor of the concentration at which effects were observed. Average ratio of acid volatile sulfides to simultaneously extractable metals was 1.4: 0.06 micromol/g indicating sufficient sulfides to sequester available metals in the system.

  11. Treatment of atrazine in nursery irrigation runoff by a constructed wetland.

    PubMed

    Runes, Heather B; Jenkins, Jeffrey J; Moore, James A; Bottomley, Peter J; Wilson, Bruce D

    2003-02-01

    To investigate the treatment capability of a surface flow wetland at a container nursery near Portland, Oregon, atrazine was introduced during simulated runoff events. Treatment efficiency was evaluated as the percent atrazine recovered (as percent of applied) in the water column at the wetland's outlet. Atrazine treatment efficiency at the outlet of the constructed wetland during a 7-d period ranged from 18-24% in 1998 (experiments 1-3) and 16-17% in 1999 (experiments 4 and 5). Changes in total flow, or frequency and intensity of runoff events did not affect treatment. For experiment 6 in 1999, where the amount, frequency, and duration of runoff events exceeded all other experiments, treatment was compromised. For all experiments, deethylatrazine (DEA) and deisopropylatrazine (DIA) accounted for 13-21% of the initial application. Hydroxyatrazine (HA) was rarely detected in the water. Organic carbon adsorption coefficients (Koc) were determined from batch equilibrium sorption isotherms with wetland sediment, and they decreased in the order of HA > DIA > atrazine > DEA. Static water-sediment column experiments indicated that sorption is an important mechanism for atrazine loss from water passing through the constructed wetland. The results of the MPN assay indicated the existence in the wetland of a low-density population of microorganisms with the potential to mineralize atrazine's ethyl side chain.

  12. Metagenomic analysis reveals microbial diversity and function in the rhizosphere soil of a constructed wetland.

    PubMed

    Bai, Yaohui; Liang, Jinsong; Liu, Ruiping; Hu, Chengzhi; Qu, Jiuhui

    2014-01-01

    Microbial communities play a critical role in the degradation of effluent contaminants in constructed wetlands. Many questions remain, however, regarding the role ofmicrobial communities in rhizospheric soil. In this study, we used metagenomic analysis to assess microbial community composition and function in a constructed wetland receiving surface water. The diversity of the microbial community of rhizosphere soil was found to be significantly greater than that of the wetland influent water. This enhancement is likely due to the availability of diverse habitats and nutrients provided by the wetland plants. From function annotation of metagenomic data, a number of biodegradation pathways associated with 14 xenobiotic compounds were identified in soil. Nitrogen fixation, nitrification and denitrification genes were semi-quantitatively analysed. By screening of manganese transformation genes, we found that the biological oxidation of Mn2+ (mainly catalysed by multicopper oxidase) in the influent water yielded insoluble Mn4+, which subsequently precipitated and were incorporated into the wetland soil. These data show that the use of metagenomic analysis can provide important new insights for the study of wetland ecosystems and, in particular, how biologically mediated transformation or degradation can be used to reduce contamination of point and non-point source wastewater.

  13. Estrogen removal from treated municipal effluent in small-scale constructed wetland with different depth.

    PubMed

    Song, Hai-Liang; Nakano, Kazunori; Taniguchi, Takashi; Nomura, Munehiro; Nishimura, Osamu

    2009-06-01

    The presence of estrone (E1), 17 beta-estradiol (E2) and 17 alpha-ethynylestradiol (EE2) in sewage treatment work (STW) effluent pose a potential risk to aquatic ecosystem. The objectives of this study were to evaluate the effectiveness of vertical-flow wetland as polishing step of conventional wastewater treatment in the removal of estrogens and to examine the effect of sand depth. The highest removal efficiency of 67.8+/-28.0%, 84.0+/-15.4% and 75.3+/-17.6% for E1, E2 and EE2, respectively, was achieved by the shallowest wetland among three constructed wetlands with different filter layer depth (i.e. 7.5, 30 and 60 cm). Together with the result that the performance of wetlands when operating in unsaturated condition was superior to that when operating in water-saturated condition, it is suggested that maintaining sufficient aerobic circumstance in constructed wetlands was important for estrogens removal. Core sampling indicated that the highest efficiency achieved in extremely shallow wetland might be due partly to the highest root density, besides the superior condition for penetration of oxygen. The adsorbed estrogens in sand accounted for less than 12% of the removed estrogens irrespective of the depth, indicating biotic processes play a major role in the estrogens removal.

  14. Characterization of Microbial Communities and Composition in Constructed Dairy Wetland Wastewater Effluent

    PubMed Central

    Ibekwe, A. Mark; Grieve, Catherine M.; Lyon, Stephen R.

    2003-01-01

    Constructed wetlands have been recognized as a removal treatment option for high concentrations of contaminants in agricultural waste before land application. The goal of this study was to characterize microbial composition in two constructed wetlands designed to remove contaminants from dairy washwater. Water samples were collected weekly for 11 months from two wetlands to determine the efficiency of the treatment system in removal of chemical contaminants and total and fecal coliforms. The reduction by the treatment was greatest for biological oxygen demand, suspended solids, chemical oxygen demand, nitrate, and coliforms. There was only moderate removal of total nitrogen and phosphorus. Changes in the total bacterial community and ammonia-oxidizing bacterial composition were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified fragments of the gene carrying the α subunit of the ammonia monooxygenase gene (amoA) recovered from soil samples and DGGE bands. DGGE analysis of wetlands and manure samples revealed that the total bacterial community composition was dominated by bacteria from phylogenetic clusters related to Bacillus, Clostridium, Mycoplasma, Eubacterium, and Proteobacteria originally retrieved from the gastrointestinal tracts of mammals. The population of ammonia-oxidizing bacteria showed a higher percentage of Nitrosospira-like sequences from the wetland samples, while a higher percentage of Nitrosomonas-like sequences from manure, feces, raw washwater, and facultative pond was found. These results show that the wetland system is a natural process dependent upon the development of healthy microbial communities for optimal wastewater treatment. PMID:12957887

  15. Effects of plant species on soil microbial processes and CH4 emission from constructed wetlands.

    PubMed

    Wang, Yanhua; Yang, Hao; Ye, Chun; Chen, Xia; Xie, Biao; Huang, Changchun; Zhang, Jixiang; Xu, Meina

    2013-03-01

    Methane (CH(4)) emission from constructed wetland has raised environmental concern. This study evaluated the influence of mono and polyculture constructed wetland and seasonal variation on CH(4) fluxes. Methane emission data showed large temporal variation ranging from 0 to 249.29 mg CH(4) m(-2) h(-1). Results indicated that the highest CH(4) flux was obtained in the polyculture system, planted with Phragmites australis, Zizania latifolia and Typha latifolia, reflecting polyculture system could stimulate CH(4) emission. FISH analysis showed the higher amount of methanotrophs in the profile of Z. latifolia in both mono and polyculture systems. The highest methanogens amount and relatively lower methanotrophs amount in the profile of polyculture system were obtained. The results support the characteristics of CH(4) fluxes. The polyculture constructed wetland has the higher potential of global warming.

  16. Feasibility of constructed wetlands for removing chlorothalonil and chlorpyrifos from aqueous mixtures.

    PubMed

    Sherrard, R M; Bearr, J S; Murray-Gulde, C L; Rodgers, J H; Shah, Y T

    2004-01-01

    Chlorpyrifos (an insecticide) and chlorothalonil (a fungicide) are transported in stormwater runoff and can be lethal to receiving aquatic system biota. This study determined removal rates of chlorpyrifos and chlorothalonil in simulated stormwater runoff treated in constructed wetland mesocosms. Using sentinel species, Ceriodaphnia dubia and Pimephales promelas, observed declines in toxicity of the simulated runoff after treatment were 98 and 100%, respectively. First order removal rates were 0.039/h for chlorpyrifos and 0.295/h for chlorothalonil in these experiments. Constructed wetland mesocosms were effective for decreasing concentrations of chlorpyrifos and chlorothalonil in simulated stormwater runoff, and decreasing P. promelas and C. dubia mortality resulting from these exposures. The results from this study indicate that constructed wetlands could be part of an efficient mitigation strategy for stormwater runoff containing these pesticides.

  17. Enhanced nitrogen removal using solid carbon source in constructed wetland with limited aeration.

    PubMed

    Yang, Zhongchen; Yang, Luhua; Wei, Caijie; Wu, Weizhong; Zhao, Xufei; Lu, Ting

    2017-08-04

    In this study, the performances of nitrogen removal in constructed wetlands using solid carbon source with limited aeration were investigated. The blends of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and polyacetic acid (PLA) were used as the carbon source and biofilm support. The performances of nitrogen removal, microbial abundance and microbial community structure in the biofilm attached on PHBV/PLA were investigated. Higher ammonia removal efficiency (91.00%) and total nitrogen removal efficiency (97.03%) than non-aerated constructed wetland (System NA) were achieved in constructed wetland with limited aeration (System A). The limited aeration decreased the average concentrations of COD in effluent. And, System A had higher microbial abundance than System NA. Pyrosequencing analysis showed that denitrifying bacteria Brevinema (41.85%) and Thiothrix (12.33%) were the predominant genus in the biofilm attached on the carbon source in System NA and System A, respectively. Copyright © 2017. Published by Elsevier Ltd.

  18. Effects of constructed wetland system on the removal of dibutyl phthalate (DBP).

    PubMed

    Liang, Wei; Deng, Jia-qi; Zhan, Fa-cui; Wu, Zhen-bin

    2009-01-01

    Phthalic acid esters (PAEs) have become widely diffused in the environment via the manufacturing process. Numerous experiments have shown that the bioaccumulation of PAEs occurred in the aquatic and terrestrial food chain; meanwhile, it was found that some of PAEs were considered as potential carcinogens, teratogens and mutagens. In this research, two vertical/reverse-vertical flow constructed wetland systems were set up to study its removal efficiency of dibutyl phthalate (DBP) pollution. The results showed that the constructed wetland system could remove DBP effectively, and the removal rates reached nearly 100%. Substrate microorganism and enzymatic activities probably played key roles during DBP removal, and the removal of DBP probably mainly took place in the upper layer of chamber A in the constructed wetland systems.

  19. METAL REMOVAL FROM PROCESS AND STORMWATER DISCHARGES BY CONSTRUCTED TREATMENT WETLANDS

    SciTech Connect

    NELSON, ERIC

    2004-11-02

    The A-01 NPDES outfall at the Savannah River Site receives process wastewater and stormwater which passes through a wetland treatment system (WTS) prior to discharge. The overall objective of our research is to better understand the mechanisms of operation of the A-01 WTS in order to provide better input to the design of future systems. The system is a vegetated surface flow wetland and has a retention time of approximately 48 hours. Sampling conducted during the fourth year of operation validated continued wetland performance, and assessed the fate of a larger suite of metals present in the water. Copper and mercury removal efficiencies were still very high, both in excess of 80 per cent removal from the water after passage through the wetland system. Lead removal from the water by the system was 83 per cent, zinc removal was 60 per cent, and nickel was generally unaffected. Nitrates entering into the wetland cells are almost immediately removed from the water column and generally no nitrates are discharged from the A cells. The wetland cells are very anaerobic and the sediments have negative redox potentials. As a result, manganese and iron mineral phases in the sediments have been reduced to soluble forms and increase in the water during passage through the wetland system. Dissolved organic carbon in the water column is also increased by the system and reduces toxicity of the effluent. Operation and maintenance of the system is minimal, and consists of checking for growth of the vegetation and free flow of the water through the system.

  20. Aquatic macroinvertebrates associated with Schoenoplectus litter in a constructed wetland in California (USA)

    USGS Publications Warehouse

    Nelson, S.M.; Thullen, J.S.

    2008-01-01

    Culm processing characteristics were associated with differences in invertebrate density in a study of invertebrates and senesced culm packs in a constructed treatment wetland. Invertebrate abundance differed by location within the wetland and there were differences between the two study years that appeared to be related to water quality and condition of culm material. Open areas in the wetland appeared to be critical in providing dissolved oxygen (DO) and food (plankton) to the important invertebrate culm processor, Glyptotendipes. As culm packs aged, invertebrate assemblages became less diverse and eventually supported mostly tubificid worms and leeches. It appears from this study that wetland design is vital to processing of plant material and that designs that encourage production and maintenance of high DO's will encourage microbial and invertebrate processing of material.

  1. Constructed wetlands to reduce diffuse pollution from agriculture

    NASA Astrophysics Data System (ADS)

    Deasy, C.; Quinton, J. N.

    2009-04-01

    Across Europe, many rivers and lakes are polluted. Sediment can disturb aquatic ecosystems, and is associated with the transport of pesticides, pathogens, toxic metals and nutrients, including phosphorus (P). P is growth-limiting in freshwaters, and rivers and lakes may become eutrophic where concentrations are high, leading to algal blooms and loss of biodiversity. For example, in the UK, the Biodiversity Action Plan estimates that over 70% of lakes are eutrophic. Concern about water quality has resulted in EU policy drivers to protect rivers and lakes. Under the requirements of the Water Framework Directive (WFD), surface waters must achieve ‘good ecological and chemical condition' by 2015. Studies in the UK indicate that P concentrations need to be an order of magnitude lower in fresh waters to comply with the requirements of the WFD, and methods of controlling sediment and P inputs into surface waters are urgently required. Pollution sources such as sewage treatment works can be regulated, but non point (diffuse) sources are difficult to control. As agricultural activities have been estimated to account for 30% of P inputs to surface waters, controlling the transfer of diffuse pollutants in runoff from agricultural land is a priority for catchment managers. The use of in-field mitigation options such as reduced tillage has been found to be effective in the UK, but pollutants can still be lost from hillslopes unchecked via subsurface runoff pathways, some of which (e.g. field drains) may contribute very high loads of sediment and P to streams. Mitigation approaches, such as wetlands, which operate at the edge-of-field, where hillslope pathways have already discharged their pollutant loads into the receiving stream, are therefore essential. Over the next two years we will establish ten wetland sites in the UK and use these to: 1) reduce levels of sediment and nutrients leaving agricultural fields; 2) determine the effectiveness of different wetland designs for

  2. Performance of Eleocharis macrostachya and its importance for arsenic retention in constructed wetlands.

    PubMed

    Olmos-Márquez, Mario Alberto; Alarcón-Herrera, Maria Teresa; Martín-Domínguez, Ignacio Ramiro

    2012-03-01

    Arsenic (As) can be removed from water via rhizofiltration using phytostabilizing plants. The aim of this study was to investigate the performance of Eleocharis macrostachya in constructed wetland prototypes, as well as the plant's arsenic mass retention and the distribution of As along the wetland flow gradient and the soil in the wetland mesocosmos. Experiments were carried out in laboratory-scale wetland prototypes, two planted with E. macrostachya and one without plants. Samples of water were taken at the inlet and outlet of the wetlands during the 33-week test period. At the end of the experiment, plants and soil (silty-sand) from each prototype were divided in three equal segments (entrance, middle and exit) and analyzed for their arsenic content. Results revealed that the planted wetlands have a higher As-mass retention capacity (87-90% of the total As inflow) than prototypes without plants (27%). As mass balance in the planted wetlands revealed that 78% of the total inflowing As was retained in the soil bed. Nearly 2% was absorbed in the plant roots, 11% was flushed as outflow, and the fate of the remaining 9% is unknown. In the prototype without plants, the soil retained 16% of As mass, 72% of the arsenic was accounted for in the outflow, and 12% was considered unknown. Although E. macrostachya retained only 2% of the total arsenic mass in their roots, its presence was a determining factor for arsenic retention in the wetland soil medium. Hence, planted wetlands might be a suitable option for treating As-contaminated water.

  3. Analysis of chemical reaction kinetics of depredating organic pollutants from secondary effluent of wastewater treatment plant in constructed wetlands.

    PubMed

    Wang, Hao; Jiang, Dengling; Yang, Yong; Cao, Guoping

    2013-01-01

    Four subsurface constructed wetlands were built to treat the secondary effluent of a wastewater treatment plant in Tangshan, China. The chemical pollutant indexes of chemical oxygen demand (COD) were analyzed to evaluate the removal efficiency of organic pollutants from the secondary effluent of the wastewater treatment plant. In all cases, the subsurface constructed wetlands were efficient in treating organic pollutants. Under the same hydraulic loading condition, the horizontal flow wetlands exhibited better efficiency of COD removal than vertical flow wetlands: the removal rates in horizontal flow wetlands could be maintained at 68.4 ± 2.42% to 92.2 ± 1.61%, compared with 63.8 ± 1.19% to 85.0 ± 1.25% in the vertical flow wetlands. Meanwhile, the chemical reaction kinetics of organic pollutants was analyzed, and the results showed that the degradation courses of the four subsurface wetlands all corresponded with the first order reaction kinetics to a large extent.

  4. Changes and characteristics of dissolved organic matter in a constructed wetland system using fluorescence spectroscopy.

    PubMed

    Yao, Yuan; Li, Yun-Zhen; Guo, Xu-Jing; Huang, Tao; Gao, Ping-Ping; Zhang, Ying-Pei; Yuan, Feng

    2016-06-01

    Domestic wastewater was treated by five constructed wetland beds in series. Dissolved organic matter (DOM) collected from influent and effluent samples from the constructed wetland was investigated using fluorescence spectroscopy combined with fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and two-dimensional correlation spectroscopy (2D-COS). This study evaluates the capability of these methods in detecting the spectral characteristics of fluorescent DOM fractions and their changes in constructed wetlands. Fluorescence excitation-emission matrix (EEM) combined with FRI analysis showed that protein-like materials displayed a higher removal ratio compared to humic-like substances. The PARAFAC analysis of wastewater DOM indicated that six fluorescent components, i.e., two protein-like substances (C1 and C6), three humic-like substances (C2, C3 and C5), and one non-humic component (C4), could be identified. Tryptophan-like C1 was the dominant component in the influent DOM. The removal ratios of six fluorescent components (C1-C6) were 56.21, 32.05, 49.19, 39.90, 29.60, and 45.87 %, respectively, after the constructed wetland treatment. Furthermore, 2D-COS demonstrated that the sequencing of spectral changes for fluorescent DOM followed the order 298 nm → 403 nm → 283 nm (310-360 nm) in the constructed wetland, suggesting that the peak at 298 nm is associated with preferential tryptophan fluorescence removal. Variation of the fluorescence index (FI) and the ratio of fluorescence components indicated that the constructed wetland treatment resulted in the decrease of fluorescent organic pollutant with increasing the humification and chemical stability of the DOM.

  5. Regulatory implications of using constructed wetlands to treat selenium-laden wastewater.

    PubMed

    Lemly, A Dennis; Ohlendorf, Harry M

    2002-05-01

    The practice of using constructed wetlands to treat selenium-laden wastewater is gaining popularity in the United States and elsewhere. However, proponents of treatment wetlands often overlook important ecological liabilities and regulatory implications when developing new methods and applications. Their research studies typically seek to answer a basic performance question--are treatment wetlands effective in improving water quality--rather than answering an implicit safety question-are they hazardous to wildlife. Nevertheless, wetland owners are responsible for both the operational performance of treatment wetlands and the health of animals that use them. This is true even if wetlands were not created with the intent of providing wildlife habitat; the owner is still legally responsible for toxic hazards. If poisoning of fish and wildlife occurs, the owner can be prosecuted under a variety of federal and state laws, for example, the Migratory Bird Treaty Act and the Endangered Species Act. In considering this type of treatment technology it is important to document the selenium content of the wastewater, understand how it cycles and accumulates in the environment, and evaluate the threat it may pose to fish and wildlife before deciding whether or not to proceed with construction. Many of the potential hazards may not be obvious to project planners, particularly if there is no expressed intention for the wetland to provide wildlife habitat. Ecological risk assessment provides an approach to characterizing proposed treatment wetlands with respect to wildlife use, selenium contamination, and possible biological impacts. Proper application of this approach can reveal potential problems and the associated liabilities, and form the basis for selection of an environmentally sound treatment option.

  6. Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan

    SciTech Connect

    Zellmer, S.D. ); Rastorfer, J.R. . Dept. of Biological Sciences ANL Van Dyke, G.D. . Dept. of Biology)

    1991-07-01

    Implementation of recent federal and state regulations promulgated to protect wetlands makes information on effects of gas pipeline rights-of-way (ROWs) in wetlands essential to the gas pipeline industry. This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth forested wetland sites mapped as Lenawee soils, one mature and one subjected to recent selective logging, were selected in Midland County, Michigan. Changes in the adjacent forest and successional development on the ROW are being documented. Cover-class estimates are being made for understory and ROW plant species using 1 {times}1-m quadrats. Counts are also being made for all woody species with stems < 2 cm in diameter at breast height (dbh) in the same plots used for cover-class estimates. Individual stem diameters and species counts are being recorded for all woody understory and overstory plants with stems {ge}2 cm dbh in 10 {times} 10-m plots. Although analyses of the data have not been completed, preliminary analyses indicate that some destruction of vegetation at the ROW forest edge may have been avoidable during pipeline construction. Rapid regrowth of many native wetland plant species on the ROW occurred because remnants of native vegetation and soil-bearing propagules of existing species survived on the ROW after pipeline construction and seeding operations. 91 refs., 11 figs., 3 tabs.

  7. Analysis of trends in water quality: constructed wetlands in metropolitan Taipei.

    PubMed

    Cheng, B-Y; Liu, T-C; Shyu, G-S; Chang, T-K; Fang, W-T

    2011-01-01

    Meandering through the most densely populated metropolitan areas of Taipei, Taiwan, the Danshui River and its tributaries have undergone the construction of 14 wetlands since 2004, as a means to improve water quality. This study was conducted to examine the functional capabilities associated with treating non-point source pollution through these riparian wetlands. Trend analysis was used to differentiate dissolved oxygen, biochemical oxygen demand, suspended solids, ammonia, and Escherichia coli, among 13 sampling sites using both functions of a Mann-Kendall test and a seasonal Mann-Kendall test. The results show that water quality in Taipei metropolitan rivers has been improving since increasing the number of constructed wetlands and connecting households to the public sewage system. The concentration of pollutants such as those influencing biochemical oxygen demand have gradually declined in drought seasons because riparian wetlands contribute a base flow to dilute riverine pollutants. This paper indicates that the creation of treatment systems influences dissolved oxygen conditions at the municipal scale, suggesting that constructed wetlands could stabilize water quality during extreme hydrological events and improve water quality particularly in times of drought.

  8. Plant Litter Submergence Affects the Water Quality of a Constructed Wetland.

    PubMed

    Pan, Xu; Ping, Yunmei; Cui, Lijuan; Li, Wei; Zhang, Xiaodong; Zhou, Jian; Yu, Fei-Hai; Prinzing, Andreas

    2017-01-01

    Plant litter is an indispensable component of constructed wetlands, but how the submergence of plant litter affects their ecosystem functions and services, such as water purification, is still unclear. Moreover, it is also unclear whether the effects of plant litter submergence depend on other factors such as the duration of litter submergence, water source or litter species identity. Here we conducted a greenhouse experiment by submerging the litter of 7 wetland plant species into three types of water substrates and monitoring changes in water nutrient concentrations. Litter submergence affected water quality positively via decreasing the concentration of nitrate nitrogen and negatively via increasing the concentrations of total nitrogen, ammonium nitrogen and total phosphorus. The effects of litter submergence depended on the duration of litter submergence, the water source, the litter species identity, and the plant life form. Different plant species had different effects on the water nutrient concentrations during litter submergence, and the effects of floating plants might be more negative than that of emergent plants. These results are novel evidence of how the submergence of different plant (life form) litter may affect the purification function of constructed wetlands. For water at low eutrophication levels, submerging a relative small amount of plant litter might improve water quality, via benefiting the denitrification process in water. These findings emphasized the management of floating plant litter (a potential removal) during the maintenance of human-controlled wetland ecosystems and provided a potential tool to improve the water quality of constructed wetlands via submerging plant litter of different types.

  9. [Characteristics of microbial biomass in subsurface constructed wetland treating eutrophic water].

    PubMed

    Fu, Rong-Bing; Zhu, Yi-Ping; Yang, Hai-Zhen; Gu, Guo-Wei

    2008-10-01

    A subsurface horizontal-flow constructed wetland planted with Phragmites australis was developed and used to treat eutrophic water for nearly two years at fixed hydraulic loading rate. Substrate samples were taken at different depths respectively in the front, middle and back sites of wetland in January, May, August and October in the second year. Microbial biomass (MB) content was measured using the chloroform fumigation incubation method. The results show that the front sites have higher levels of microbial biomass carbon (MB-C), microbial biomass nitrogen (MB-N) and microbial biomass phosphorous (MB-P) than that in middle sites and back sites. The upper layers have higher levels of MB than that in the deeper layers. The MB content of wetland in January and May is higher than that in October and August. The relationship between MB and TN, TP removal efficiency of the constructed wetland was investigated. The wetland shows no apparent correlation of MB and TN removal efficiency. However, strong negative correlation is observed between MB-C and TP removal efficiency (r = -0.98, p < 0.05) and between MB-N, MB-P and TP removal efficiency (r = -0.99, p < 0.01). In constructed wetland, MB is also an active nutrient storage involved in nutrient cycling and can be used by wetland plant. MB content varies among a range level with plant growth and temperature in a growth year. Under experiment conditions, the range of MB-C, MB-N and MB-P was respectively 85.0-160.6, 16.3-34.9 and 3.12-5.77 microg x g(-1) in the second year. Seasonal variation of MB and nutrient removal is resulted from the factors integrated with temperature, microorganisms, plant, substrate and enzyme.

  10. Microbial diversity of bacteria, archaea, and fungi communities in a continuous flow constructed wetland for the treatment of swine waste

    USDA-ARS?s Scientific Manuscript database

    Contaminant removal in constructed wetlands may largely be a function of many microbial processes. However, information about bacterial, archaea, and fungi communities in constructed wetlands for the removal of swine waste is limited. In this study, we used 454/GS-FLX pyrosequencing to assess bacter...

  11. Assessing the impact of pipeline construction on coniferous wetlands in central Michigan with aerial photography

    NASA Technical Reports Server (NTRS)

    Kittleson, K. M.; Mcdavitt, M. E.

    1980-01-01

    The Remote Sensing Project at Michigan State University is using repetitive aerial photography to assess the impact of pipeline construction on coniferous wetlands in central Michigan. Preliminary results indicate that ponding, dieback, windthrow, and vegetation changes are readily detectable on medium-scale aerial photography. It is found that the major effect of the pipeline construction is the alteration of the water level, either by flooding or dessication. The most serious damage generally occurs when pipelines cross seepage and spiring wetland types; specific damage is related to the impoundment of the natural water flow, producing flooding on the upflow side of the pipeline and dessication of these wetlands below the pipeline rights-of-way.

  12. Nitrogen transformations and balance in constructed wetlands for slightly polluted river water treatment using different macrophytes.

    PubMed

    Wu, Haiming; Zhang, Jian; Wei, Rong; Liang, Shuang; Li, Cong; Xie, Huijun

    2013-01-01

    Nitrogen removal processing in different constructed wetlands treating different kinds of wastewater often varies, and the contribution to nitrogen removal by various pathways remains unclear. In this study, the seasonal nitrogen removal and transformations as well as nitrogen balance in wetland microcosms treating slightly polluted river water was investigated. The results showed that the average total nitrogen removal rates varied in different seasons. According to the mass balance approach, plant uptake removed 8.4-34.3 % of the total nitrogen input, while sediment storage and N(2)O emission contributed 20.5-34.4 % and 0.6-1.9 % of nitrogen removal, respectively. However, the percentage of other nitrogen loss such as N(2) emission due to nitrification and denitrification was estimated to be 2.0-23.5 %. The results indicated that plant uptake and sediment storage were the key factors limiting nitrogen removal besides microbial processes in surface constructed wetland for treating slightly polluted river water.

  13. Hydraulics and flow modelling of water treatment wetlands constructed on peatlands in Northern Finland.

    PubMed

    Ronkanen, Anna-Kaisa; Kløve, Bjørn

    2008-08-01

    In this study, we evaluated flow structure, effective flow area (A(eff)) and effective porosity (theta(eff)) in three peatlands using the stable isotope (18)O/(16)O ratio and tracer tests. We also applied the readily available groundwater modelling MODFLOW code for wetland flow modelling and simulated in one study site how the hydraulic performance of the wetland will be improved by changing the design of the distribution ditch. Preferential flow paths occurred in all three studied wetlands and A(eff) varied from 40% to 90% of total wetland area while theta(eff) was 0.75-0.99. Constructed flow models accurately simulated the hydraulic head across wetlands (r(2)=0.95-0.99). Similarities between the flow models and the stable isotope distributions observed in this study suggest possibilities in using MODFLOW to design peatlands. The improvement of the inlet ditch configuration (ditch length/wetland width>0.45) can prevent or reduce short-circuiting and dead zones in peatlands treating wastewater.

  14. Relationships between Spatial Metrics and Plant Diversity in Constructed Freshwater Wetlands.

    PubMed

    Brandt, Erika C; Petersen, John E; Grossman, Jake J; Allen, George A; Benzing, David H

    2015-01-01

    The diversity of plant species and their distribution in space are both thought to have important effects on the function of wetland ecosystems. However, knowledge of the relationships between plant species and spatial diversity remains incomplete. In this study, we investigated relationships between spatial pattern and plant species diversity over a five year period following the initial restoration of experimental wetland ecosystems. In 2003, six identical and hydrologically-isolated 0.18 ha wetland "cells" were constructed in former farmland in northeast Ohio. The systems were subjected to planting treatments that resulted in different levels of vascular plant species diversity among cells. Plant species diversity was assessed through annual inventories. Plant spatial pattern was assessed by digitizing low-altitude aerial photographs taken at the same time as the inventories. Diversity metrics derived from the inventories were significantly related to certain spatial metrics derived from the photographs, including cover type diversity and contagion. We found that wetlands with high cover type diversity harbor higher plant species diversity than wetlands with fewer types of patches. We also found significant relationships between plant species diversity and spatial patterning of patch types, but the direction of the effect differed depending on the diversity metric used. Links between diversity and spatial pattern observed in this study suggest that high-resolution aerial imagery may provide wetland scientists with a useful tool for assessing plant diversity.

  15. [Reduction of hyperspectral dimensions and construction of discriminating models for identifying wetland plant species].

    PubMed

    Liu, Xue-hua; Sun, Yan; Wu, Yan

    2012-02-01

    The present paper researched and analyzed the hyperspectral data of wetland plant species often occurred in Beijing. The methods of Mahalanobis Distance (MD) and principal component analysis (PCA) were mainly applied to reduce the dimensions of hyperspectral data and to analyze and extract the features of spectra. The authors use the extracted spectra to build identification models for identifying the wetland species. The authors then compared and evaluated the precisions of models and finally obtained the best discriminating model. The results showed that (1) the dimensions of hyperspectral data can be efficiently reduced by both MD and PCA methods. (2) The discriminating models established using the parameters extracted from the resulting spectra of MD and PCA could identify the wetland plants with high precisions of more than 90%. As a result, the conversion and usage of the hyperspectral data can help better understand and well extract the spectra of different wetland plants. Furthermore, the constructed discriminating models for wetland species could also be used in the future to guide us in mapping and monitoring of wetland ecosystem by applying the remote sensing data.

  16. Relationships between Spatial Metrics and Plant Diversity in Constructed Freshwater Wetlands

    PubMed Central

    Grossman, Jake J.; Allen, George A.; Benzing, David H.

    2015-01-01

    The diversity of plant species and their distribution in space are both thought to have important effects on the function of wetland ecosystems. However, knowledge of the relationships between plant species and spatial diversity remains incomplete. In this study, we investigated relationships between spatial pattern and plant species diversity over a five year period following the initial restoration of experimental wetland ecosystems. In 2003, six identical and hydrologically-isolated 0.18 ha wetland “cells” were constructed in former farmland in northeast Ohio. The systems were subjected to planting treatments that resulted in different levels of vascular plant species diversity among cells. Plant species diversity was assessed through annual inventories. Plant spatial pattern was assessed by digitizing low-altitude aerial photographs taken at the same time as the inventories. Diversity metrics derived from the inventories were significantly related to certain spatial metrics derived from the photographs, including cover type diversity and contagion. We found that wetlands with high cover type diversity harbor higher plant species diversity than wetlands with fewer types of patches. We also found significant relationships between plant species diversity and spatial patterning of patch types, but the direction of the effect differed depending on the diversity metric used. Links between diversity and spatial pattern observed in this study suggest that high-resolution aerial imagery may provide wetland scientists with a useful tool for assessing plant diversity. PMID:26296205

  17. Vertical flow constructed wetlands: kinetics of nutrient and organic matter removal.

    PubMed

    Pérez, M M; Hernández, J M; Bossens, J; Jiménez, T; Rosa, E; Tack, F

    2014-01-01

    The kinetics of organic matter and nutrient removal in a pilot vertical subsurface wetland with red ferralitic soil as substrate were evaluated. The wetland (20 m(2)) was planted with Cyperus alternifolius. The domestic wastewater that was treated in the wetland had undergone a primary treatment consisting of a septic moat and a buffer tank. From the sixth week of operation, the performance of the wetland stabilized, and a significant reduction in pollutant concentration of the effluent wastewater was obtained. Also a significant increase of dissolved oxygen (5 mg/l) was obtained. The organic matter removal efficiency was greater than 85% and the nutrient removal efficiency was greater than 75% in the vertical subsurface wetland. Nitrogen and biochemical oxygen demand (BOD) removal could be described by a first-order model. The kinetic constants were 3.64 and 3.27 d(-1) for BOD and for total nitrogen, respectively. Data on the removal of phosphorus were adapted to a second-order model. The kinetic constant was 0.96 (mg/l)(-1) d(-1). The results demonstrated the potential of vertical flow constructed wetlands to clean treated domestic wastewater before discharge into the environment.

  18. [Treatment of oilfield produced water by biological methods-constructed wetland process and degradation characteristics of organic substances].

    PubMed

    Huang, Xiang-feng; Shen, Jie; Wen, Yue; Liu, Jia; Lu, Li-jun; Zhou, Qi

    2010-02-01

    Hydrolysis acidification-aerobic-constructed wetland process and hydrolysis acidification-constructed wetland were used to treat oilfield produced water after the pretreatment of oil separation-coagulation. Gas chromatography-mass spectrometry was used to study the degradation characteristics of organic substances during the treatment process. The results showed that COD and ammonia nitrogen of both the two process effluents were below 80 mg/L and 15 mg/L, respectively, when HRT was 20 h for hydrolysis acidification, 10 h for aeration and 2 d for constructed wetlands or when HRT was 20 h for hydrolysis acidification and 4 d for constructed wetland. The results of GC-MS analysis showed that biodegradability of the oil produced water was significantly improved in hydrolysis acidification. Substantial removal of benzene compounds was achieved in aerobic and constructed wetland.

  19. Five year water and nitrogen balance for a constructed surface flow wetland treating agricultural drainage waters.

    PubMed

    Borin, Maurizio; Tocchetto, Davide

    2007-07-15

    The performance of a constructed surface flow wetland in reducing diffuse N pollution coming from croplands is being investigated in an ongoing experiment, begun in 1998 in NE Italy. The 0.32 ha wetland is vegetated with Phragmites australis (Cav.) Trin. and Typha latifolia (L.). It receives drainage water from 6 ha of land managed for an experiment on drainage systems, where maize, sugarbeet, winter wheat and soybean are cultivated. During the period 1998-2002, the wetland received from 4698 to 8412 mm of water per year (on average, about 9 times the environmental rainfall); its water regimen was discontinuous and flooding occurred on a variable number of days per year (from 13 to 126). Nitric nitrogen was the most important form of element load. Its concentration in the inflow water over time was rather discontinuous, with median values ranging from 0.2 (in 2001) to 4.5 (in 2000) mg L(-1). Inflow nitric N concentrations were occasionally in the 5-15 mg L(-1) range. Concentrations reduced passing through the wetland, with a more evident effect in the last year. Over 5 years, the wetland received slightly more than 2000 kg ha(-1) of nitrogen, 87% in nitric form mostly from farmland drainage. The remaining 13% of N was applied as organic slurry directly onto the wetland, with 5 distributions during 1998 to assess wetland performance in treating occasional organic loads. Field drainage loads had a discontinuous time pattern and occurred mostly during autumn-winter, with the exception of the 2001-2002 season which was a very dry. The wetland discharged 206 kg ha(-1) of N, over the 5-year period, with an apparent removal efficiency of about 90%. The disappearance was mostly due to plant uptake (1110 kg ha(-1)) and soil accumulation (570 kg ha(-1)), with the contribution of denitrification being estimated at around 7%.

  20. Evaluating acute toxicity of methyl parathion application in constructed wetland mesocosms.

    PubMed

    Milam, C D; Bouldin, J L; Farris, J L; Schulz, R; Moore, M T; Bennett, E R; Cooper, C M; Smith, S

    2004-10-01

    Wetland ecosystems have reduced ambient levels of various organic and metallic compounds, although their effectiveness on agricultural pesticides is not well documented. Five stations within each of two 10 x 50 m constructed wetlands (two vegetated, two nonvegetated) were selected to measure the fate and effects of methyl parathion (MeP). Following a simulated storm event (0.64 cm of rainfall), aqueous, sediment, and plant samples were collected and analyzed spatially (5, 10, 20, and 40 m from the inlet) and temporally (after 3-10 days) for MeP concentrations and for the impact of those concentrations on the aquatic fauna. Aqueous toxicity to fish decreased spatially and temporally in the vegetated mesocosm. Pimephales promelas survival was significantly reduced, to 68%, at the 10-m station of the nonvegetated wetlands (3 h postapplication), with pesticide concentrations averaging 9.6 microg MeP/L. Ceriodaphnia in both the vegetated and nonvegetated wetlands was sensitive (i.e., a significant acute response to MeP occurred) to pesticide concentrations through 10 days postapplication. Mean MeP concentrations in water ranged from 0.5 to 15.4 microg/L and from 0.1 to 27.0 microg/L in the vegetated and nonvegetated wetlands, respectively. Hyalella azteca aqueous tests resulted in significant mortality in the 5-m vegetated segment 10 days after exposure to MeP (2.2 microg/L). Solid-phase (10-day) sediment toxicity tests showed no significant reduction in Chironomus tentans survival or growth, except for the sediments sampled 3 h postapplication in the nonvegetated wetland (65% survival). Thereafter, midge survival averaged >87% in sediments sampled from both wetlands. These data suggest that wetlands play a significant role in mitigating the effect of MeP exposure in sensitive aquatic biota. Copyright 2004 Wiley Periodicals, Inc.

  1. Aquatic macrophytes can be used for wastewater polishing but not for purification in constructed wetlands

    NASA Astrophysics Data System (ADS)

    Tang, Yingying; Harpenslager, Sarah F.; van Kempen, Monique M. L.; Verbaarschot, Evi J. H.; Loeffen, Laury M. J. M.; Roelofs, Jan G. M.; Smolders, Alfons J. P.; Lamers, Leon P. M.

    2017-02-01

    The sequestration of nutrients from surface waters by aquatic macrophytes and sediments provides an important service to both natural and constructed wetlands. While emergent species take up nutrients from the sediment, submerged and floating macrophytes filter nutrients directly from the surface water, which may be more efficient in constructed wetlands. It remains unclear, however, whether their efficiency is sufficient for wastewater purification and how plant species and nutrient loading affects nutrient distribution over plants, water and sediment. We therefore determined nutrient removal efficiencies of different vegetation (Azolla filiculoides, Ceratophyllum demersum and Myriophyllum spicatum) and sediment types (clay, peaty clay and peat) at three nutrient input rates, in a full factorial, outdoor mesocosm experiment. At low loading (0.43 mg P m-2 d-1), plant uptake was the main pathway (100 %) for phosphorus (P) removal, while sediments showed a net P release. A. filiculoides and M. spicatum showed the highest biomass production and could be harvested regularly for nutrient recycling, whereas C. demersum was outcompeted by spontaneously developing macrophytes and algae. Higher nutrient loading only stimulated A. filiculoides growth. At higher rates ( ≥ 21.4 mg P m-2 d-1), 50-90 % of added P ended up in sediments, with peat sediments becoming more easily saturated. For nitrogen (N), 45-90 % was either taken up by the sediment or lost to the atmosphere at loadings ≥ 62 mg N m-2 d-1. This shows that aquatic macrophytes can indeed function as an efficient nutrient filter but only for low loading rates (polishing) and not for high rates (purification). The outcome of this controlled study not only contributes to our understanding of nutrient dynamics in constructed wetlands but also shows the differential effects of wetland sediment types and plant species. Furthermore, the acquired knowledge may benefit the application of macrophyte harvesting to remove

  2. Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste.

    PubMed

    Ibekwe, A M; Ma, J; Murinda, Shelton; Reddy, G B

    2016-02-15

    Constructed wetlands are generally used for the removal of waste from contaminated water. In the swine production system, wastes are traditionally flushed into an anaerobic lagoon which is then sprayed on agricultural fields. However, continuous spraying of lagoon wastewater on fields can lead to high N and P accumulations in soil or lead to runoff which may contaminate surface or ground water with pathogens and nutrients. In this study, continuous marsh constructed wetland was used for the removal of contaminants from swine waste. Using pyrosequencing, we assessed bacterial composition within the wetland using principal coordinate analysis (PCoA) which showed that bacterial composition from manure influent and lagoon water were significantly different (P=0.001) from the storage pond to the final effluent. Canonical correspondence analysis (CCA) showed that different bacterial populations were significantly impacted by ammonium--NH4 (P=0.035), phosphate--PO4(3-) (P=0.010), chemical oxygen demand--COD (P=0.0165), total solids--TS (P=0.030), and dissolved solids--DS (P=0.030) removal, with 54% of the removal rate explained by NH4+PO4(3-) according to a partial CCA. Our results showed that different bacterial groups were responsible for the composition of different wetland nutrients and decomposition process. This may be the major reason why most wetlands are very efficient in waste decomposition. Published by Elsevier B.V.

  3. Seasonal effect on ammonia nitrogen removal by constructed wetlands treating polluted river water in southern Taiwan.

    PubMed

    Jing, Shuh-Ren; Lin, Ying-Feng

    2004-01-01

    A pilot-scale constructed wetland (CW) system, combining a free water surface wetland and a subsurface wetland in series, was used to purify highly polluted river water. The concentrations of constituents varied seasonally. The effects of season-dependent parameters, such as temperature, mass loading rate and inflow salinity, on the removal of ammonia nitrogen (AN) in the wetland system were examined at a constant hydraulic loading rate, based on data from June 1998 to February 2000. AN removal of the CW varied cyclically with the seasons. The removal efficiency and the first-order volumetric removal rate constant (k(V)) increased exponentially with water temperature, yielding a high temperature coefficient (theta). However, the mass removal rate decreased exponentially as temperature increased. These contradictory results made the actual effect of temperature uncertain. The inhibition of high water salinity on AN removal was also unclear because k(V) (as well as k(V20)) and mass removal rate were inversely proportional to salinity. However, mass loading rate (MLR) predominantly affected both the removal efficiency and the mass removal rate of AN, both of which were factors that explicitly determined seasonality. A power equation, k(V20)' alpha MLR(-n), was proposed to correct the variation of the mass loading rate in estimating k(V) and thus in designing a constructed wetland.

  4. Use of Constructed Wetlands for Urban Stream Restoration: A CriticalAnalysis

    PubMed

    Helfield; Diamond

    1997-05-01

    / Investigation of a delta marsh restoration project proposed forthe Don River in Toronto, Ontario, underlines several concerns aboutconstructed wetland projects designed for water quality improvement andaquatic habitat enhancement. The Don is a highly urbanized river that hasundergone significant physiographic modifications and continually receives acomplex mixture of conventional, metallic, and organic contaminants frommultiple point and nonpoint sources. Rather than providing permanent removalof urban contaminants, wetland processes offer a limited capacity fortemporary storage of contaminant inputs, and potential reactions may actuallyproduce more toxic and/or bioavailable forms of some chemicals. Theseprocesses tend to result in the concentration of watershed contaminants inwetland vegetation and sediments. As the restored marsh would be availablefor spawning and feeding by aquatic fauna, the potential exists for chemicalbioconcentration and biomagnification through the aquatic community.Accordingly, wetland systems are not suited to the dual purposes of waterquality improvement and aquatic habitat enhancement. Upstream controls,including source reduction of contaminant inputs, are recommended asessential components of all constructed wetland projects.KEY WORDS: Constructed wetlands; Water quality; Ecological restoration;Don River

  5. The design of vegetative constructed wetlands for the treatment of highway runoff.

    PubMed

    Shutes, R B; Revitt, D M; Lagerberg, I M; Barraud, V C

    1999-09-01

    The Environment Agency for England and Wales are responsible for assessing the effects of highway runoff and for monitoring the treatment systems/procedures which have been introduced for the reduction of deleterious effects. The Agency is looking into the improvement of surface water management in terms of best management practices and plans to work in partnership with the Highways Agency to achieve this aim. Among the treatment options being considered are constructed wetlands. Draft Guidelines have been developed to provide information on their design. This paper describes procedures for carrying out an Environmental Sensitivity Analysis to determine whether treatment by a constructed wetland is appropriate. Information on water quality and quantity is required as well as the sensitivity of the receiving environment. The legislative position, particularly in relation to the discharge quality of the water and the conservation status of the receiving environment, needs also to be considered. The factors that will determine the most appropriate wetland design criteria include traffic loadings, road drainage area, land availability, cost and the size/extent and type of the receiving water body. The following structures are recommended for incorporation in the overall design; oil separator and silt trap, spillage containment, settlement pond, vegetative wetland and final settlement tank. The operation and maintenance procedures and the monitoring requirements for a functioning wetland are described.

  6. Wastewater treatment in tsunami affected areas of Thailand by constructed wetlands.

    PubMed

    Brix, H; Koottatep, T; Laugesen, C H

    2007-01-01

    The tsunami of December 2004 destroyed infrastructure in many coastal areas in South-East Asia. In January 2005, the Danish Government gave a tsunami relief grant to Thailand to re-establish the wastewater management services in some of the areas affected by the tsunami. This paper describes the systems which have been built at three locations: (a) Baan Pru Teau: A newly-built township for tsunami victims which was constructed with the contribution of the Thai Red Cross. Conventional septic tanks were installed for the treatment of blackwater from each household and its effluent and grey water (40 m3/day) are collected and treated at a 220 m2 subsurface flow constructed wetland. (b) Koh Phi Phi Don island: A wastewater collection system for the main business and hotel area of the island, a pumping station and a pressure pipe to the treatment facility, a multi-stage constructed wetland system and a system for reuse of treated wastewater. The constructed wetland system (capacity 400 m3/day) consists of vertical flow, horizontal subsurface flow, free water surface flow and pond units. Because the treatment plant is surrounded by resorts, restaurants and shops, the constructed wetland systems are designed with terrains as scenic landscaping. (c) Patong: A 5,000 m2 constructed wetland system has been established to treat polluted water from drainage canals which collect overflow from septic tanks and grey water from residential areas. It is envisaged that these three systems will serve as prototype demonstration systems for appropriate wastewater management in Thailand and other tropical countries.

  7. Trace Metal Accumulation in Sediments and Benthic Macroinvertebrates before and after Maintenance of a Constructed Wetland

    EPA Science Inventory

    Periodic maintenance of stormwater best management practices (BMP) includes the removal of accumulated sediment. The resulting impact on trace metal concentrations of copper (Cu), lead (Pb), and zinc (Zn) in a constructed stormwater wetland BMP on Staten Island, NY was investiga...

  8. FREE-WATER DEPTH AS A MANAGEMENT TOOL FOR CONSTRUCTED WETLANDS

    EPA Science Inventory

    Marsh plants in constructed wetlands have shown the capacity to remove unwanted pollutants from storm water runoff. The plants can be established at the site from bare roots. However, plant growth from bare roots can be restricted by the elevated water depths. Using several wa...

  9. SEASONAL MONITORING OF ELEMENTS AT THREE CONSTRUCTED TREATMENT WETLANDS: 1999-2001

    EPA Science Inventory

    A suite of major, minor, and trace elements in sediment, pore water, and overlying water were monitored during winter and summer over a three year period at three different types of constructed treatment wetlands to evaluate their efficacy with season. Acid-volatile sulfide (AVS)...

  10. Enhanced Nitrification in Constructed Wetlands Using Ion-Exchange and Biological Regeneration

    DTIC Science & Technology

    2000-10-30

    Constructed wetlands built in northern climates do not adequately remove nitrogen, especially ammoniacal nitrogen, in the winter. Clinoptilolite , an...environmental constraints. The ammonium-sorbed clinoptilolite can be biologically regenerated during the summer months, when conditions are more conducive for...nitrification. Laboratory scale and pilot scale studies were conducted to prove this hypothesis and develop design criteria for a clinoptilolite

  11. Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands

    Treesearch

    Lihu Cui; Ying Ouyang; Weizhi Yang; Zhujian Huang; Qiaoling Xu; Guangwei Yu

    2015-01-01

    Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs...

  12. Simulating phosphorus removal from a vertical-flow constructed wetland grown with C. alternifolius species

    USDA-ARS?s Scientific Manuscript database

    Vertical flow constructed wetland (VFCW) is a promising engineering technique for removal of excess nutrients and certain pollutants from wastewater and stormwater. The aim of this study was to develop a STELLA (Structural Thinking, Experiential Learning Laboratory with Animation) model for estimati...

  13. Constructed wetlands as green tools for management of boron mine wastewater.

    PubMed

    Türker, Onur Can; Türe, Cengiz; Böcük, Harun; Yakar, Anil

    2014-01-01

    Constructed wetlands are of increasing interest worldwide given that they represent an eco-technological solution to many environmental problems such as wastewater treatment. Turkey possesses approximately 70% of the world's total boron (B) reserves, and B contamination occurs in both natural and cultivated sites throughout Turkey, particularly in the north-west of the country. This study analyzes B removal and plant uptake of B in pilot plots of subsurface horizontal-flow constructed wetlands. Constructed wetlands were vegetated with Typha latifolia (referred to as CW1) and Phragmites australis (referred to as CW2) to treat wastewater from a borax reserve in Turkey--the largest of its type in the world and were assessed under field conditions. The B concentrations of water inflows to the systems were determined to be 10.2, 28.2, 84.6, 232.3, 716.4, and 2019.1 mg l(-1). The T. latifolia in the CW1 treatment group absorbed a total of 1300 mg kg(-1) B, whereas P. australis absorbed 839 mg kg(-1). As a result, CW1 had an average removal efficiency of 40.7%, while that of CW2 was 27.2%. Our results suggest that constructed wetlands are an effective, economic and eco-friendly solution to treating B mine wastewater and controlling the adverse environmental effects of B mining.

  14. ASSESSMENT OF AN INFILTRATION BASIN AND CONSTRUCTED WETLAND FOR REMOVAL OF PATHOGENS FROM FEEDLOT RUNOFF

    EPA Science Inventory

    The use of an infiltration basin and constructed wetland to treat process wastewater from a cattle feedlot prior to discharge to an adjacent waterway was explored in regards to fecal pathogens. Weekly sampling of typical operating conditions and rainfall-generated runoff during 2...

  15. Trace Metal Accumulation in Sediments and Benthic Macroinvertebrates before and after Maintenance of a Constructed Wetland

    EPA Science Inventory

    Periodic maintenance of stormwater best management practices (BMP) includes the removal of accumulated sediment. The resulting impact on trace metal concentrations of copper (Cu), lead (Pb), and zinc (Zn) in a constructed stormwater wetland BMP on Staten Island, NY was investiga...

  16. Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste

    USDA-ARS?s Scientific Manuscript database

    Constructed wetlands are generally used for the removal of waste from contaminated water. In the swine production system, wastes are traditionally flushed into an anaerobic lagoon which is then sprayed on agricultural fields. However, continuous spraying of lagoon wastewater on fields can lead to hi...

  17. Ammonia and greenhouse gas emissions from constructed wetlands treating swine wastewater

    USDA-ARS?s Scientific Manuscript database

    Ammonia and greenhouse gas emissions from marsh-pond-marsh constructed wetlands treating swine wastewater were measured with closed-chamber technique using a photoacoustic multigas analyzer. Theory behind the technique was discussed and the technique was demonstrated with actual field data. Nitrous ...

  18. ASSESSMENT OF AN INFILTRATION BASIN AND CONSTRUCTED WETLAND FOR REMOVAL OF PATHOGENS FROM FEEDLOT RUNOFF

    EPA Science Inventory

    The use of an infiltration basin and constructed wetland to treat process wastewater from a cattle feedlot prior to discharge to an adjacent waterway was explored in regards to fecal pathogens. Weekly sampling of typical operating conditions and rainfall-generated runoff during 2...

  19. FREE-WATER DEPTH AS A MANAGEMENT TOOL FOR CONSTRUCTED WETLANDS

    EPA Science Inventory

    Marsh plants in constructed wetlands have shown the capacity to remove unwanted pollutants from storm water runoff. The plants can be established at the site from bare roots. However, plant growth from bare roots can be restricted by the elevated water depths. Using several wa...

  20. Removal of chlorophenolics from pulp and paper mill wastewater through constructed wetland.

    PubMed

    Choudhary, Ashutosh Kumar; Kumar, Satish; Sharma, Chhaya

    2013-01-01

    This study evaluates the treatment efficiency of horizontal subsurface flow (HSSF) constructed wetland for the removal of AOX (adsorbable organic halides) and chlorophenolics from pulp and paper mill wastewater. The dimensions of HSSF constructed wetland were 3.5 m in length, 1.5 m in width, and 0.28 m in depth, with surface area of 5.25 m2. The HSSF constructed wetland unit was planted with an ornamental plant species, Canna indica. Under hydraulic retention time (HRT) of 5.9 days, the average AOX removal was 89.1%, and 67% to 100% removal of chlorophenolics from pulp and paper mill wastewater was achieved. The complete removal of 2,3-dichlorophenol, 3,4-dichlorophenol, 2,3,5-trichlorophenol, 2,4,6-trichlorophenol, 3,5-dichlorocatechol, 3,6-dichlorocatechol, and 4,5,6-trichloroguaiacol was observed. Some of the chlorophenolics were found to accumulate in the plant biomass and soil. The evapotranspiration rate varied from 6.7 to 12.7 mm day(-1) during the experimental period. The mass balance of chlorophenolics was also studied in constructed wetland system.

  1. The Revival of a Failed Constructed Wetland Treating of a High Fe Load AMD

    Treesearch

    A.D. Karathanasis; C.D. Barton

    1999-01-01

    Acid mine drainage (AMD) from abandoned mines has significantly impaired water quality in eastern Kentucky. A small surface flow wetland constructed in 1989 to reduce AMD effects and subsequently failed after six months of operation was renovated by incorporating anoxic limestone drains (ALDs) and anaerobic subsurface drains promoting vertical flow through successive...

  2. Removal of Nutrients from Septic Effluent with Re-circulated Hybrid Tidal Flow Constructed Wetland

    Treesearch

    Lihua Cui; Jigkun Feng; Ying Ouyang; Peiwen. Deng

    2012-01-01

    Hybrid tidal flow constructed wetland (CW) with recirculation is an improved biological and engineering technique for removal of excess nutrients and certain pollutants from wastewater. This study investigated the removal efficiency of total phosphorus (TP), ammonia-nitrogen (NH3-N), and total nitrogen (TN) from septic tank effluent with the hybrid tidal flow CW system...

  3. Simulating phosphorus removal from a vertical-flow constructed wetland grown with C alternifolius species

    Treesearch

    Ying Ouyang; Lihua Cui; Gary Feng; John Read

    2015-01-01

    Vertical flow constructed wetland (VFCW) is a promising technique for removal of excess nutrients and certain pollutants from wastewaters. The aim of this study was to develop a STELLA (structural thinking, experiential learning laboratory with animation) model for estimating phosphorus (P) removal in an artificial VFCW (i.e., a substrate column with six zones) grown...

  4. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity of Hyalella azteca

    USDA-ARS?s Scientific Manuscript database

    The toxicity of a nutrient-pesticide mixture in non-vegetated and vegetated sections of a constructed wetland (60 X 30 X 0.3 m) was assessed using Hyalella azteca 48 h aqueous whole effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple super phosphate, dia...

  5. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosms

    USDA-ARS?s Scientific Manuscript database

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures such as nutrients only (N, P), pesticides only (atrazine, S-metolachlor, permethrin), and nutrients+pesticides on phytoplankton chlorophyll a, 48 h aqueous Hyalella azteca survival, and 10 d se...

  6. [Effect of design and operation parameters on volatile alkylsulfides removal in subsurface constructed wetlands].

    PubMed

    Feng, Lin; Gan, Li; Wang, Hua-jie; Mo, Ping; Huang, Yu-ming

    2010-02-01

    A pilot-scale subsurface constructed wetland wastewater treatment system was sampled for one year to study the effects of bed aspect ratio, substrate medium size, water depth, HLR (hydraulic loading rate) and temperature (season) on removal of volatile alkylsulfides such as DMS (dimethylsulfide) and DMDS (dimethyldisulfide). The yearly experimental results demonstrated that the system showed good performance for DMS and DMDS removal in wastewater under different HLR ranging from 12 cm x d(-1) to 86 cm x d(-1). The system could remove 86% of DMS, and 95% of DMDS, respectively. ANOVA statistical analysis shows that HLR and temperature (season) are major factors controlling the system performance for the target analytes. According to ANOVA test, the HLR caused significant differences (p < 0.01) on the average DMS effluent concentrations, and temperature (season) caused significant differences (p < 0.01) on the average DMS and DMDS effluent concentrations. However, bed aspect ratio, substrate medium size and water depth did not cause significant differences (p > 0.05) on the average DMS and DMDS effluent concentrations. A survey of dissolved oxygen and ORP indicates that the constructed wetlands system showed strong reduced condition. On the basis of investigations of electron acceptors (such as SO4(2-), NO3- and NO2-) and dissolved organic pollutants (such as TOC and acetic acid) concentrations along with the length of constructed wetlands, it can be concluded that sulfate reduction and methanogenisis were estimated to be significant for DMS and DMDS removal in constructed wetland beds.

  7. Pollutant swapping: greenhouse gas emissions from wetland systems constructed to mitigate agricultural pollution

    NASA Astrophysics Data System (ADS)

    Freer, Adam; Quinton, John; Surridge, Ben; McNamara, Niall

    2014-05-01

    Diffuse (non-point) water pollution from agricultural land continues to challenge water quality management, requiring the adoption of new land management practices. The use of constructed agricultural wetlands is one such practice, designed to trap multiple pollutants mobilised by rainfall prior to them reaching receiving water. Through capturing and storing pollutants in bottom sediments, it could be hypothesised that the abundance of nutrients stored in the anoxic conditions commonly found in these zones may lead to pollutant swapping. Under these circumstances, trapped material may undergo biogeochemical cycling to change chemical or physical form and thereby become more problematic or mobile within the environment. Thus, constructed agricultural wetlands designed to mitigate against one form of pollution may in fact offset the created benefits by 'swapping' this pollution into other forms and pathways, such as through release to the atmosphere. Pollutant swapping to the atmosphere has been noted in analogous wetland systems designed to treat municipal and industrial wastewaters, with significant fluxes of CO2, CH4 and N2O being recorded in some cases. However the small size, low level of engineering and variable nutrient/sediment inputs which are features of constructed agricultural wetlands, means that this knowledge is not directly transferable. Therefore, more information is required when assessing whether a wetland's potential to act as hotspot for pollution swapping outweighs its potential to act as a mitigation tool for surface water pollution. Here we present results from an on-going monitoring study at a trial agricultural wetland located in small a mixed-use catchment in Cumbria, UK. Estimates were made of CH4, CO2 and N2O flux from the wetland surface using adapted floating static chambers, which were then directly compared with fluxes from an undisturbed riparian zone. Results indicate that while greenhouse gas flux from the wetland may be

  8. Influence of substrate type on microbial community structure in vertical-flow constructed wetland treating polluted river water.

    PubMed

    Guan, Wei; Yin, Min; He, Tao; Xie, Shuguang

    2015-10-01

    Microorganisms attached on the surfaces of substrate materials in constructed wetland play crucial roles in the removal of organic and inorganic pollutants. However, the impact of substrate material on wetland microbial community structure remains unclear. Moreover, little is known about microbial community in constructed wetland purifying polluted surface water. In this study, Illumina high-throughput sequencing was applied to profile the spatial variation of microbial communities in three pilot-scale surface water constructed wetlands with different substrate materials (sand, zeolite, and gravel). Bacterial community diversity and structure showed remarkable spatial variation in both sand and zeolite wetland systems, but changed slightly in gravel wetland system. Bacterial community was found to be significantly influenced by wetland substrate type. A number of bacterial groups were detected in wetland systems, including Proteobacteria, Chloroflexi, Bacteroidetes, Acidobacteria, Cyanobacteria, Nitrospirae, Planctomycetes, Actinobacteria, Firmicutes, Chlorobi, Spirochaetae, Gemmatimonadetes, Deferribacteres, OP8, WS3, TA06, and OP3, while Proteobacteria (accounting for 29.1-62.3 %), mainly composed of Alpha-, Beta-, Gamma-, and Deltaproteobacteria, showed the dominance and might contribute to the effective reduction of organic pollutants. In addition, Nitrospira-like microorganisms were abundant in surface water constructed wetlands.

  9. Influence of earthworm Eisenia fetida on removal efficiency of N and P in vertical flow constructed wetland.

    PubMed

    Xu, Defu; Li, Yingxue; Howard, Alan

    2013-09-01

    This study investigates biomass, density, photosynthetic activity, and accumulation of nitrogen (N) and phosphorus (P) in three wetland plants (Canna indica, Typha augustifolia, and Phragmites austrail) in response to the introduction of the earthworm Eisenia fetida into a constructed wetland. The removal efficiency of N and P in constructed wetlands were also investigated. Results showed that the photosynthetic rate (P n), transpiration rate (T r), and stomatal conductance (S cond) of C. indica and P. austrail were (p < 0.05) significantly higher when earthworms were present. The addition of E. fetida increased the N uptake value by above-ground of C. indica, T. augustifolia, and P. australis by 185, 216, and 108 %, respectively; and its P uptake value increased by 300, 355, and 211 %, respectively. Earthworms could enhance photosynthetic activity, density, and biomass of wetland plants in constructed wetland, resulting in the higher N and P uptake. The addition of E. fetida into constructed wetland increased the removal efficiency of TN and TP by 10 and 7 %, respectively. The addition of earthworms into vertical flow constructed wetland increased the removal efficiency of TN and TP, which was related to higher photosynthetic activity and N and P uptake. The addition of earthworms into vertical flow constructed wetland and plant harvests could be the significantly sustainable N and P removal strategy.

  10. The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture.

    PubMed

    Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan

    2003-01-01

    A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of the culture tank on the growth and survival of shrimp postlarvae. During an 80-day culture period, the wetland unit operated at a mean hydraulic loading rate of 0.3 m/day and effectively reduced the influent concentrations of 5-day biochemical oxygen demand (BOD5, 24%), suspended solids (SS, 71%), chlorophyll a (chl-a, 88%), total ammonium (TAN, 57%), nitrite nitrogen (NO2-N, 90%) and nitrate nitrogen (NO3-N, 68%). Phosphate (PO4-P) reduction was the least efficient (5.4%). The concentrations of SS, Chl-a, turbidity and NO3-N in the culture tank water in RAS were significantly (Pwetland treatment. However, no significant difference (Pconstructed wetlands can improve the water quality and provide a good culture environment, consequently increasing the shrimp growth and survival without water exchange, in a recirculating system.

  11. How efficient are constructed wetlands in removing pharmaceuticals from untreated and treated urban wastewaters? A review.

    PubMed

    Verlicchi, Paola; Zambello, Elena

    2014-02-01

    This review presents and discusses the data from 47 peer-reviewed journal articles on the occurrence of 137 pharmaceutical compounds in the effluent from various types of constructed wetlands treating urban wastewater. We analyse the observed removal efficiencies of the investigated compounds in order to identify the type of constructed wetland that best removes those most frequently detected. The literature reviewed details experimental investigations carried out on 136 treatment plants, including free water surface systems, as well as horizontal and vertical subsurface flow beds (pilot or full-scale) acting as primary, secondary or tertiary treatments. The occurrence of selected pharmaceuticals in sediments and gravel and their uptake by common macrophytes are also presented and discussed. We analyse the main removal mechanisms for the selected compounds and investigate the influence of the main design parameters, as well as operational and environmental conditions of the treatment systems on removal efficiency. We also report on previous attempts to correlate observed removal values with the chemical structure and chemical-physical properties (mainly pKa and LogKow) of pharmaceutical compounds. We then use the literature data to calculate the average pharmaceutical mass loadings in the effluent from constructed wetlands, comparing the ability of such systems to remove selected pharmaceuticals with the corresponding conventional secondary and tertiary treatments. Finally, the environmental risk posed by pharmaceutical residues in effluents from constructed wetlands acting as secondary and tertiary treatment steps is calculated in the form of the risk quotient ratio. This approach enabled us to provide a ranking of the most critical compounds for the two scenarios, to discuss the ramifications of the adoption of constructed wetlands for removing such persistent organic compounds, and to propose avenues of future research. © 2013.

  12. The potential for constructed wetlands to treat alkaline bauxite residue leachate: laboratory investigations.

    PubMed

    R, Buckley; T, Curtin; R, Courtney

    2016-07-01

    High alkalinity (pH > 12) of bauxite residue leachates presents challenges for the long-term storage and managements of the residue. Whilst the use of constructed wetlands is gaining in interest for its use in the treatment of alkaline waters, thus far, there is limited evidence of its suitability for treating NaOH dominated bauxite residue leachate. A series of batch trials were conducted to investigate the potential for constructed wetland conferred mechanisms (dilution water quality, contact with CO2, and substrate type) for treating NaOH solutions to levels permissible for discharge (p < 9). Results demonstrate that significant reductions in solution pH can be achieved depending on the diluting water quality. Levels achieved may not always be suitable for direct discharge (i.e. pH ≤ 9), but further reductions occur with carbonation and soil contact. The extent of pH decrease and the timeframe required are influenced by soil quality, with greater efficiency observed in soils with higher organic matter content. Decrease in solution pH to discharge permit values are possible through a combination of the mechanisms occurring in a constructed wetland. Formation of a calcite precipitate was observed in some treatments and further characterisation by XRD and XPS suggested surface coating with Na2CO3. It is therefore suggested that, under suitable conditions, constructed wetland technology can reduce leachate pH to <9 through mechanisms supporting the precipitation of sodium carbonate from solution. Further trials should investigate the activity under biological conditions representative of an operating constructed wetland.

  13. Pathways of nitrobenzene degradation in horizontal subsurface flow constructed wetlands: Effect of intermittent aeration and glucose addition.

    PubMed

    Kirui, Wesley K; Wu, Shubiao; Kizito, Simon; Carvalho, Pedro N; Dong, Renjie

    2016-01-15

    Intermittent aeration and addition of glucose were applied to horizontal subsurface flow constructed wetlands in order to investigate the effect on pathways of nitrobenzene (NB) degradation and interactions with microbial nitrogen and sulphur transformations. The experiment was carried out in three phases A, B and C consisting of different NB loading and glucose dosing. For each phase, the effect of aeration was assessed by intermittently aerating one wetland and leaving one unaerated. Regardless of whether or not the wetland was aerated, at an influent NB concentration of 140 mg/L, both wetlands significantly reduced NB to less than 2 mg/L, a reduction efficiency of 98%. However, once the influent NB concentration was increased to 280 mg/L, the aerated wetland had a higher removal performance 82% compared to that of the unaerated wetland 71%. Addition of glucose further intensified the NB removal to 95% in the aerated wetlands and 92% in the unaerated. Aeration of wetlands enhanced NB degradation, but also resulted in higher NB volatilization of 6 mg m(-2) d(-1). The detected high concentration of sulphide 20-60 mg/L in the unaerated wetland gave a strong indication that NB may act as an electron donor to sulphate-reducing bacteria, but this should be further investigated. Aeration positively improved NB removal in constructed wetlands, but resulted in higher NB volatilization. Glucose addition induced co-metabolism to enhance NB degradation.

  14. Study of Geochemical System in Constructed Wetland Using Multivariate Statistical Analysis

    NASA Astrophysics Data System (ADS)

    Chen, V.

    2015-12-01

    People have recognized that the human activities lead to the degradation of the environment, and constructed wetland is one of the well-known technologies for water treatment. In constructed wetland, complicated processes should be considered such as redox reactions, acid-base reactions, adsorption-desorption between water and sediment and biochemical reactions associated with plant and microorganism. In this study, most of inorganic components were analyzed and principal component analysis (PCA) was followed for depicting the controlling biochemical reaction in the constructed wetland. The results could be a guide to operate the constructed wetland. The constructed wetland in this study is located in Taoyuan County, north Taiwan. It's a horizontal subsurface flow constructed wetland composed of ten cells. The water in wetland was pumped from Nankan River, which collects wastewater from Hwaya technology park, Linkou, Guishan and Nankan industrial zone. The water of inflow and outflow from each cell were collected for analyzing inorganic components with ICP-MS and IC. In general, the results show that water quality had dramatically changed in the first three cells and became stable in the following seven cells. In this study, PCA extracted two major factors (PCs), which can respectively explain 52.76%(PC1)and 28.32%(PC2)of variance of water quality data. PC1 separates samples of the first three cells from those of the other following cells. It is believed that there was another pollution source involved in the 4th cell because PC1 is characterized by high loadings of most of trace heavy metals. On the other hand, the hydrochemistry of water mainly evolve along PC2 axis. PC2 is composed of Fe, Mn, NH4, dissolved oxygen, pH, etc with high loadings. These chemical components are predominately controlled by redox reactions. Moreover, the deep water from the 4th cell contains high concentrations of many heavy metals, especially Cu and Ga. This confirms the

  15. Indicators of biofilm development and activity in constructed wetlands microcosms.

    PubMed

    Ragusa, S R; McNevin, D; Qasem, S; Mitchell, C

    2004-07-01

    Methods to measure protein, exopolysaccharide, viable cell number and INT reduction activity were tested on biofilm growing in a wastewater batch reactor. They were shown to be meaningful indicators of biofilm growth and correlated well with each other. Protein, exopolysaccharide, viable cells and INT reduction rates increased linearly over time. Viable cell number exhibited strong linear correlations with protein (R2= 0.98) and exopolysaccharide (R2= 0.99) while INT reduction rate was somewhat less well correlated (R2= 0.90). Our results indicate production rates of 0.91 x 10(-7) microg EPS per viable cell and 1.0 x 10(-7) microg protein per viable cell. Protein and polysaccharide specific INT reduction rates decreased by approximately 50%, whereas viable cell specific INT reduction rates decreased by 65% and the protein to polysaccharide ratio stayed relatively constant at between 1.1 and 1.2 as the biofilm developed. Measurement of protein, polysaccharide, viable cells and INT reduction rate at depth within the bioreactor showed that they were concentrated in the top 1cm of the influent end of the reactor and each decreased to a base level within 4.5 cm of the inlet. Protein to polysaccharide ratios increased with depth in the reactor and the specific INT reduction rates were maximal at 4.5 cm depth. The results indicate that the biomass can take upwards of 100 days to stabilize during batch (fill and draw) operation of subsurface wetlands and that the relative ratios of biomass components remain relatively constant during biofilm growth. Also, it appears that filtration of suspended solids results in biomass concentration at the inlet to the wetland.

  16. Performance and cost evaluation of constructed wetland for domestic waste water treatment.

    PubMed

    Deeptha, V T; Sudarsan, J S; Baskar, G

    2015-09-01

    Root zone treatment through constructed wetlands is an engineered method of purifying wastewater. The aim of the present research was to study the potential of wetland plants Phragmites and Typha in treatment of wastewater and to compare the cost of constructed wetlands with that of conventional treatment systems. A pilot wetland unit of size 2x1x0.9 m was constructed in the campus. 3x3 rows of plants were transplanted into the pilot unit and subjected to wastewater from the hostels and other campus buildings. The raw wastewater and treated wastewater were collected periodically and tested for Total nitrogen (TN),Total Phosphorous (TP), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD). It was observed that this pilot unit reduced the concentrations of TN, TP, BOD and COD by 76, 73, 83 and 86%, respectively, on an average. Root zone system achieved standards for tertiary treatment with low operating costs, low maintenance costs, enhance the landscape, provide a natural habitat for birds, and did not emit any odour.

  17. The use of constructed wetlands for removal of pesticides from agricultural runoff and drainage: a review.

    PubMed

    Vymazal, Jan; Březinová, Tereza

    2015-02-01

    Pesticides are used in modern agriculture to increase crop yields, but they may pose a serious threat to aquatic ecosystems. Pesticides may enter water bodies through diffuse and point sources, but diffuse sources are probably the most important. Among diffuse pollution, surface runoff and erosion, leaching and drainage represent the major pathways. The most commonly used mitigation techniques to prevent pesticide input into water bodies include edge-of-field and riparian buffer strips, vegetated ditches and constructed wetlands. The first attempts to use wetland macrophytes for pesticide removal were carried out as early as the 1970s, but only in the last decade have constructed wetlands for pesticide mitigation become widespread. The paper summarizes 47 studies in which removal of 87 pesticides was monitored. The survey revealed that constructed wetlands with free water surface are the most commonly used type. Also, it has been identified that removal of pesticides is highly variable. The results of the survey revealed that the highest pesticide removal was achieved for pesticides of the organochlorine, strobilurin/strobin, organosphosphate and pyrethroid groups while the lowest removals were observed for pesticides of the triazinone, aryloxyalkanoic acid and urea groups. The removal of pesticides generally increases with increasing value of KOC but the relationship is not strong. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Removal of mercury from gold mine effluents using Limnocharis flava in constructed wetlands.

    PubMed

    Marrugo-Negrete, José; Enamorado-Montes, Germán; Durango-Hernández, José; Pinedo-Hernández, José; Díez, Sergi

    2017-01-01

    Phytoremediation has received increased attention over the recent decades, as an emerging and eco-friendly approach that utilizes the natural properties of plants to remediate contaminated water, soils or sediments. The current study provides information about a pilot-scale experiment designed to evaluate the potential of the anchored aquatic plant Limnocharis flava for phytoremediation of water contaminated with mercury (Hg), in a constructed wetland (CW) with horizontal subsurface flow (HSSF). Mine effluent used in this experiment was collected from a gold mining area located at the Alacran mine in Colombia (Hg: 0.11 ± 0.03 μg mL(-1)) and spiked with HgNO3 (1.50 ± 0.09 μg mL(-1)). Over a 30 day test period, the efficiency of the reduction in the heavy metal concentration in the wetlands, and the relative metal sorption by the L. flava, varied according to the exposure time. The continued rate of removal of Hg from the constructed wetland was 9 times higher than the control, demonstrating a better performance and nearly 90% reduction in Hg concentrations in the contaminated water in the presence of L. flava. The results in this present study show the great potential of the aquatic macrophyte L. flava for phytoremediation of Hg from gold mining effluents in constructed wetlands.

  19. Invertebrates associated with a horizontal-flow, subsurface constructed wetland in a northern climate.

    PubMed

    Giordano, Rosanna; Weber, Everett; Darby, Brian J; Soto-Adames, Felipe N; Murray, Robert E; Drizo, Aleksandra

    2014-04-01

    Wetlands function as buffers between terrestrial and aquatic ecosystems, filtering pollutants generated by human activity. Constructed wetlands were developed to mimic the physical and biological filtering functions of natural systems for the treatment of human and animal waste under controlled conditions. Previous studies on the effect of constructed wetlands on native invertebrate populations have concentrated almost exclusively on mosquitoes. Here, we present the first study investigating the relationship between vegetation cover and aeration regime, and the diversity and abundance of nematodes and springtails (Collembola) in a constructed wetland designed to treat dairy farm wastewater in northwestern Vermont. We investigated four treatment cells differing in aeration regime and vegetation cover, but equally overlaid by a layer of compost to provide insulation. Analysis showed that nematodes were most abundant in the nonplanted and nonaerated cells, and that bacterivorous nematodes dominated the community in all cells. Springtails were found to be most numerous in the planted and nonaerated cells. We hypothesize that the vegetation provided differing environmental niches that supported a more diverse system of bacteria and fungi, as well as offering protection from predators and inclement weather. Nematodes were likely imported with the original compost material, while springtails migrated into the cells either via air, water, or direct locomotion.

  20. Qualitative variability in microbial community of constructed wetlands used for purifying wastewater contaminated with pharmaceutical substances.

    PubMed

    Nowrotek, Monika; Ziembińska-Buczyńska, Aleksandra; Miksch, Korneliusz

    2015-01-01

    Pharmaceutical substances and their residues are increasingly present in the environment. Therefore, attempts at their removal are made by using different processes. Increasingly important among these processes are those modeled on natural phenomena which occur in wetland ecosystems, called technical scale constructed wetlands. Microbial degradation is an important process in these constructed wetlands. The biodegradation of chemicals often involves a complex series of biochemical reactions and usually varies with the microorganisms involved. The objectives of this study were to determine the impact of sulfamethoxazole and diclofenac on ammonia oxidizing bacteria and other parameters of wastewater in the microcosm of down-flow constructed wetlands. The Spearman correlation coefficient attained negative values in the case of comparison of the Shannon biodiversity index and the parameters of purified wastewater. This dependence was pronounced. In the case of pharmaceutical substances dosed with wastewater, the Spearman correlation coefficient assumed positive values. The highest value assumed by the Spearman correlation coefficient (0.9) was for the removal of diclofenac and Shannon index values for the planted columns, with a very high relationship. For unplanted columns, this value equaled 0.6. For sulfamethoxazole, the value for planted columns was 0.7, and for unplanted -0.7. The presence of plants did not have an impact on the Shannon biodiversity index.

  1. Effects of acidification on metal accumulation by aquatic plants and invertebrates. 1. Constructed wetlands

    USGS Publications Warehouse

    Albers, P.H.; Camardese, M.B.

    1993-01-01

    The pH of lake water is often inversely correlated with concentrations of trace metals in the water column. Concentrations of Al, Cd, Ca, Cu, Fe, Hg, Pb, Mg, Mn, Ni, P, and Zn were compared in water, plants, and aquatic insects from three acidified (pH 5.0) and three nonacidified (pH 6.5) constructed wetlands. Concentrations of Zn in water and bur-reed (Sparganium americanum) were higher in acidified wetlands than in nonacidified wetlands. Floating nonrooted plants contained mean concentrations of Fe, Mg, and Mn that were higher than recommended maximum levels for poultry feed. The mean concentrations of all metals in insects were below recommended maximum levels for poultry feed and below levels that cause toxic effects in wild birds. Smaller than expected increases of metal concentrations in the water of acidified wetlands were probably due to limited mobilization of metals from the sediments and insignificant changes in sedimentation of aqueous metals. Calcium was lower in acidified than in nonacidified wetland water, but the Ca content of insects and bur-reed was not lower. Low concentrations of Ca in aquatic insects from both groups of wetlands indicate that calcium-rich crustaceans and mollusks are probably important to female waterfowl and their young during the spring, when invertebrates make up the majority of the diet. Although toxic effects from metal ingestion seem to be unlikely consequences of wetland acidification, the adverse effect of low pH on the occurrence of crustaceans and mollusks could threaten egg production and development of young.

  2. Chemical characterization of iron oxide precipitates from wetlands constructed to treat polluted mine drainage

    SciTech Connect

    Fish, C.L.; Partezana, J.M.; Hedin, R.S.

    1996-12-31

    The passive treatment of abandoned mine drainage using wetlands will produce a significant amount of iron rich sludge which will require costly removal and disposal. An alternative to disposal may be the use of this iron oxide material as pigments which could defray some of these costs. In this research, iron deposits from five alkaline mine drainage wetlands were collected and a series of standard tests were run. The tests included loss on ignition, moisture, pH, acid soluble metals, oil absorption, and water soluble matter. The results of these tests were compared to those achieved using commercially available natural and synthetic iron oxides. The results indicate that iron oxides from constructed wetlands have chemical properties that are intermediate to those of natural and synthetic iron oxide products.

  3. Removal of nutrients and metals by constructed and naturally created wetlands in the Las Vegas Valley, Nevada.

    PubMed

    Adhikari, Achyut R; Acharya, Kumud; Shanahan, Seth A; Zhou, Xiaoping

    2011-09-01

    Increased water use associated with rapid growth in the Las Vegas Valley has inadvertently led to the creation of unique wetland systems in Southern Nevada with an abundance of biological diversity. Constructed and naturally created wetlands in the Las Vegas Valley watershed were studied to characterize and understand their potential role for improving ecosystem services (i.e., water purification). Nutrient and metal removal was assessed at four sites including a natural urban runoff wetland, a constructed urban runoff wetland, a constructed wastewater wetland, and a natural urban runoff/wastewater wetland. Plant nutrient uptake was dependent on ambient nutrient concentrations in water and sediments of specific wetlands, irrespective of the type of plants present. Phosphorus was mostly concentrated in below-ground plant parts whereas nitrogen was concentrated in above-ground parts. As for metalloids, bulrushes were more efficient than cattails at taking up arsenic and selenium. Averaging all the wetland sites and plant species, total nitrogen, phosphorus, arsenic and selenium removal was 924.2, 61.5, 0.30, and 0.38 kg/ha/year, respectively. Our findings suggest that natural and created wetland systems can improve water quality in the Las Vegas Valley watershed for some common pollutants, however, other measures are still needed to improve water quality below regulatory thresholds.

  4. Microbial community response during the treatment of pharmaceutically active compounds (PhACs) in constructed wetland mesocosms.

    PubMed

    Yan, Qing; Min, Jie; Yu, Yonghong; Zhu, Zhiwei; Feng, Guozhong

    2017-11-01

    The presence of pharmaceutically active compounds (PhACs) in wastewater treatment plant effluent poses a potential risk to aquatic ecosystems. Constructed wetlands have recently been used to control PhACs. However, the microbial communities that are involved in these processes have not been comprehensively investigated. This study aimed to evaluate the removal of PhACs and microbial response in constructed wetlands during the treatment of PhACs. The effects of PhACs on bacterial communities in constructed wetland mesocosms were analyzed by Illumina MiSeq sequencing technology. Results indicated that removal efficiencies of PhACs were enhanced over time, and constructed wetlands offer higher removal efficiencies for the PhACs studied compared to conventional wastewater treatment plants. Plants improved microbial richness and diversity while both indices were negatively correlated with PhAC concentrations ranging from 30 to 500 μg/L in constructed wetland mesocosms. The microbial communities of the constructed wetland mesocosms were dominated by Proteobacteria, Acidobacteria, and Bacteroidetes under PhAC exposure, while Desulfobulbus and Treponema were the dominant genera. In particular, Proteobacteria were correlated with PhAC concentrations. Overall, this study provides valuable microbial community ecology data to understand how microbial populations respond to PhAC stress in constructed wetlands. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. The role of constructed wetlands for biomass production within the water-soil-waste nexus.

    PubMed

    Avellan, C T; Ardakanian, R; Gremillion, P

    2017-05-01

    The use of constructed wetlands for water pollution control has a long standing tradition in urban, peri-urban, rural, agricultural and mining environments. The capacity of wetland plants to take up nutrients and to filter organic matter has been widely discussed and presented in diverse fora and published in hundreds of articles. In an ever increasingly complex global world, constructed wetlands not only play a role in providing safe sanitation in decentralized settings, shelter for biodiversity, and cleansing of polluted sites, in addition, they produce biomass that can be harvested and used for the production of fodder and fuel. The United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES) was established in December 2012 in Dresden, Germany, to assess the trade-offs between and among resources when making sustainable decisions. Against the backdrop of the Water-Energy-Food Nexus, which was introduced as a critical element for the discussions on sustainability at Rio +20, the UNU was mandated to pay critical attention to the interconnections of the underlying resources, namely, water, soil and waste. Biomass for human consumption comes in the form of food for direct use, as fodder for livestock, and as semi-woody biomass for fuelling purposes, be it directly for heating and cooking or for the production of biogas and/or biofuel. Given the universal applicability of constructed wetlands in virtually all settings, from arid to tropical, from relatively high to low nutrient loads, and from a vast variety of pollutants, we postulate that the biomass produced in constructed wetlands can be used more extensively in order to enhance the multi-purpose use of these sites.

  6. Field investigation of advanced filtration for phosphorus removal from constructed treatment wetland effluents.

    PubMed

    Calder, N; Anderson, B C; Martin, D G

    2006-10-01

    Three sorptive media, blast furnace slag, cement clinker, and gravel were investigated for their capacity to remove phosphorus in a subsurface flow constructed treatment wetland post-treatment filter. Three filters were designed: two containing a mixture of either slag and gravel or clinker and gravel, and one with gravel only as the control filter. They were installed as a demonstration polishing treatment step to a constructed treatment wetland treating residential wastewater collected from 137 mobile home units at the Sunny Creek Estates Mobile Home Park. The filters were commissioned during the summer of the field season, with the data gathering taking place over a period of one year. The slag filter consistently had the lowest outflow dissolved phosphorus concentrations (0.27 +/- 0.08 mg l(-1), n=21), whereas the clinker filter had the highest outflow dissolved phosphorus concentrations (0.72 +/- 0.20 mg l(-1), n=23). The clinker filter performed well below expectations based on previous laboratory investigations, possibly due to lower pH conditions encountered in the field study. All of the filters maintained relatively constant outflow concentrations of phosphorus below 1 mg l(-1), despite varying input conditions and environmental factors such as temperature and phosphorus loading, and the occurrence of net export of phosphorus from the wetland. Net export of phosphorus from the filters occurred in the winter months, which was attributed to the decrease in input phosphorus concentrations below the maintained outflow concentrations (leading to phosphorus desorption), rather than cold temperatures or failure of the filter. Although the exact mechanisms of phosphorus removal are still under investigation, the results from this field study allowed for recommendations to be made for improving phosphorus removal at the Sunny Creek Estates constructed treatment wetland, in addition to providing valuable information for new and existing constructed treatment

  7. Treatment of domestic wastewater by subsurface flow constructed wetlands filled with gravel and tire chip media.

    PubMed

    Richter, A Y; Weaver, R W

    2003-12-01

    Subsurface flow constructed wetlands (SFCWs) are becoming increasingly common in on-site treatment of wastewater. Gravel is the most popular form of wetland fill medium, but tire chips provide more porosity, are less dense, and less expensive. This study determines the treatment efficiency of SFCWs filled with gravel or tire chip media to treat domestic wastewater. The influent and effluent of six SFCWs filled with tire chip medium and six SFCWs filled with gravel were monitored for 5 to 16 consecutive months. Parameters measured included pH, biochemical oxygen demand (BOD5), total and volatile suspended solids, NH4, P, and fecal and total coliforms. The only clear difference between medium types in wetland performance was for P. Soluble P in the effluent averaged 1.6 +/- 1.0 mg l(-1) in the tire chip-filled wetlands and 4.8 +/- 3.2 mg l(-1) in the gravel-filled wetlands. Most likely, Fe from exposed wires in shredded steel-belted tires complexed with P to create an insoluble compound. Tire chips may be a better fill medium for SFCWs than gravel because of higher porosity, lower cost, and greater reduction of P in effluent.

  8. Environmental monitoring and assessment of the water bodies of a pre-construction urban wetland.

    PubMed

    Zuo, Shengpeng; Wan, Kun; Zhou, Shoubiao; Ye, Liangtao; Ma, Sumin

    2014-11-01

    It is planned that the Dayanghan Wetland in China will be transformed into a national park but little is known about its current water quality and pollution status. Thus, we monitored the physical and chemical characteristics of the Dayanghan Wetland, which showed that the water quality was generally good. However, the chemical oxygen demand was more than double the reference value, which may be attributable to previous tillage for vegetable crops and other farmlands. In addition, nickel and chromium caused low-level pollution in the water bodies of the Dayanghan Wetland. The mean trophic level index and nutrient quality index were 39.1 and 2.69, respectively. Both indices suggest that the water bodies of the Dayanghan Wetland are in a mesotrophic state and that no eutrophication has occurred. The study would provide a precise report on the status of environmental quality of the water bodies of a typical pre-construction wetland for the administration and decision of the local government and the planning agent.

  9. Vegetation type and layer depth influence nitrite-dependent methane-oxidizing bacteria in constructed wetland.

    PubMed

    Yang, Mengxi; Guo, Qingwei; Tong, Tianli; Li, Ningning; Xie, Shuguang; Long, Yan

    2017-04-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) process might be an important methane sink in wetland system. However, information on n-damo microorganisms in constructed wetland (CW) system for water treatment is still lacking. The present study investigated the n-damo communities in five full-scale vertical-flow CW systems with different plants. N-damo bacterial abundance did not show a considerable shift in CW planted with Cyperus papyrus, but varied greatly in other CW systems. However, the evident vertical change of n-damo community diversity occurred in each CW system. These CW systems displayed the different vertical change trends for either n-damo community abundance or diversity. In addition, CW n-damo community structure could change with wetland layer depth. At a given wetland layer depth, the evident difference of n-damo community abundance, diversity and structure could be observed in the five different CW systems. Both wetland layer depth and vegetation type could contribute to the shift of n-damo bacterial abundance and community structure in CWs.

  10. A microcosm study on remediation of explosives-contaminated groundwater using constructed wetlands.

    PubMed

    Sikora, F J; Behrends, L L; Phillips, W D; Coonrod, H S; Bailey, E; Bader, D F

    1997-11-21

    Anaerobic degradation of TNT and TNB in gravel systems was rapid and similar to removal rates in parrot feather lagoons. Planted and unplanted anaerobic gravel systems were the only treatments that provided significant reduction of RDX and HMX. Planted systems with parrot feather had no effect on removal rates of explosives in anaerobic gravel systems. Reciprocating wetlands were not effective in biodegrading RDX or HMX, but were very efficient at removing COD. A scaled-up concept for bioremediating contaminated groundwater can be envisioned with the data obtained in the current study. The effectiveness of anaerobic gravel systems indicate an anaerobic subsurface-flow constructed wetland can be established as the primary treatment for remediation with C added to the influent or step fed down the length of the wetland. Another option would be to add compost as a more permanent source of C to the gravel substrate. With time, the need for C supplementation may be reduced with the C exudates and redox lowering potential of certain plants like canarygrass (Phalaris arundinacea). As a secondary treatment, a reciprocating wetland would appear to be a logical choice to quickly remove C released in effluent waters of the anaerobic wetland.

  11. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW).

    PubMed

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg · L(-1)). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (ΦPS II) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities.

  12. Removing heavy metals from Isfahan composting leachate by horizontal subsurface flow constructed wetland.

    PubMed

    Bakhshoodeh, Reza; Alavi, Nadali; Soltani Mohammadi, Amir; Ghanavati, Hossein

    2016-06-01

    Composting facility leachate usually contains high concentrations of pollutants including heavy metals that are seriously harmful to the environment and public health. The main purpose of this study was to evaluate heavy metals removal from Isfahan composting facility (ICF) leachate by a horizontal flow constructed wetland (HFCWs) system. Two horizontal systems were constructed, one planted with vetiver and the other without plant as a control. They both operated at a flow rate of 24 L/day with a 5-day hydraulic retention time (HRT). The average removal efficiencies for Cr (53 %), Cd (40 %), Ni (35 %), Pb (30 %), Zn (35 %), and Cu (40 %) in vetiver constructed wetland were significantly higher than those of the control (P < 0.05). Accumulations of heavy metals in roots were higher than shoots. Cd and Zn showed the highest and the lowest bioconcentration factor (BCF), respectively. Vetiver tolerates the extreme condition in leachate including high total dissolved solids.

  13. General design, construction, and operation guidelines: Constructed wetlands wastewater treatment systems for small users including individual residences. Second edition

    SciTech Connect

    Steiner, G.R.; Watson, J.T.

    1993-05-01

    One of the Tennessee Valley Authority`s (TVA`s) major goals is cleanup and protection of the waters of the Tennessee River system. Although great strides have been made, point source and nonpoint source pollution still affect the surface water and groundwater quality in the Tennessee Valley and nationally. Causes of this pollution are poorly operating wastewater treatment systems or the lack of them. Practical solutions are needed, and there is great interest and desire to abate water pollution with effective, simple, reliable and affordable wastewater treatment processes. In recognition of this need, TVA began demonstration of the constructed wetlands technology in 1986 as an alternative to conventional, mechanical processes, especially for small communities. Constructed wetlands can be downsized from municipal systems to small systems, such as for schools, camps and even individual homes.

  14. Distribution of Organic Carbon in the Sediments of Xinxue River and the Xinxue River Constructed Wetland, China

    PubMed Central

    Cao, Qingqing; Wang, Renqing; Zhang, Haijie; Ge, Xiuli; Liu, Jian

    2015-01-01

    Wetland ecosystems are represented as a significant reservoir of organic carbon and play an important role in mitigating the greenhouse effect. In order to compare the compositions and distribution of organic carbon in constructed and natural river wetlands, sediments from the Xinxue River Constructed Wetland and the Xinxue River, China, were sampled at two depths (0–15 cm and 15–25 cm) in both upstream and downstream locations. Three types of organic carbon were determined: light fraction organic carbon, heavy fraction organic carbon, and dissolved organic carbon. The results show that variations in light fraction organic carbon are significantly larger between upstream and downstream locations than they are between the two wetland types; however, the opposite trend is observed for the dissolved organic carbon. There are no significant differences in the distribution of heavy fraction organic carbon between the discrete variables (e.g., between the two depths, the two locations, or the two wetland types). However, there are significant cross-variable differences; for example, the distribution patterns of heavy fraction organic carbon between wetland types and depths, and between wetland types and locations. Correlation analysis reveals that light fraction organic carbon is positively associated with light fraction nitrogen in both wetlands, while heavy fraction organic carbon is associated with both heavy fraction nitrogen and the moisture content in the constructed wetland. The results of this study demonstrate that the constructed wetland, which has a relatively low background value of heavy fraction organic carbon, is gradually accumulating organic carbon of different types, with the level of accumulation dependent on the balance between carbon accumulation and carbon decomposition. In contrast, the river wetland has relatively stable levels of organic carbon. PMID:26230255

  15. Distribution of Organic Carbon in the Sediments of Xinxue River and the Xinxue River Constructed Wetland, China.

    PubMed

    Cao, Qingqing; Wang, Renqing; Zhang, Haijie; Ge, Xiuli; Liu, Jian

    2015-01-01

    Wetland ecosystems are represented as a significant reservoir of organic carbon and play an important role in mitigating the greenhouse effect. In order to compare the compositions and distribution of organic carbon in constructed and natural river wetlands, sediments from the Xinxue River Constructed Wetland and the Xinxue River, China, were sampled at two depths (0-15 cm and 15-25 cm) in both upstream and downstream locations. Three types of organic carbon were determined: light fraction organic carbon, heavy fraction organic carbon, and dissolved organic carbon. The results show that variations in light fraction organic carbon are significantly larger between upstream and downstream locations than they are between the two wetland types; however, the opposite trend is observed for the dissolved organic carbon. There are no significant differences in the distribution of heavy fraction organic carbon between the discrete variables (e.g., between the two depths, the two locations, or the two wetland types). However, there are significant cross-variable differences; for example, the distribution patterns of heavy fraction organic carbon between wetland types and depths, and between wetland types and locations. Correlation analysis reveals that light fraction organic carbon is positively associated with light fraction nitrogen in both wetlands, while heavy fraction organic carbon is associated with both heavy fraction nitrogen and the moisture content in the constructed wetland. The results of this study demonstrate that the constructed wetland, which has a relatively low background value of heavy fraction organic carbon, is gradually accumulating organic carbon of different types, with the level of accumulation dependent on the balance between carbon accumulation and carbon decomposition. In contrast, the river wetland has relatively stable levels of organic carbon.

  16. Metal removal by sulphate-reducing bacteria from natural and constructed wetlands.

    PubMed

    Webb, J S; McGinness, S; Lappin-Scott, H M

    1998-02-01

    The use of wetlands is a promising technology to treat acid mine drainage, yet there is little understanding of the fundamental biological processes involved. They are considered to centre on the complex anaerobic ecology within sediments and involve the removal of metals by sulphate-reducing bacteria (SRB). These bacteria generate hydrogen sulphide and cause precipitation of metals from solution as the insoluble metal sulphide. Sulphate-reducing bacteria have been isolated from natural and constructed wetlands receiving acid mine drainage. Sulphide production by isolates and removal of the metals iron, manganese and zinc were measured, as well as utilization of a range of carbon sources. Marked ecological differences between the wetlands were reflected in population composition of SRB enrichments, and these consortia displayed significant differences in sulphide generation and rates of metal removal from solution. Rates of metal removal did not correlate with sulphide generation in all cultures, suggesting the involvement of other biological mechanisms of metal removal. Differences in substrate utilization have highlighted the need for further investigation of carbon flow and potential carbon sources within constructed wetlands.

  17. The phytoremediation ability of a polyculture constructed wetland to treat boron from mine effluent.

    PubMed

    Türker, Onur Can; Böcük, Harun; Yakar, Anıl

    2013-05-15

    This study focuses on describing the ability of a small-scale, subsurface-flow-polyculture-constructed wetland (PCW) to treat boron (B) mine effluent from the world's largest borax mine (Kırka, Turkey) under field conditions. This application is among the first effluent treatment methods of this type in both Turkey and the world. This study represents an important resource on how subsurface-flow-constructed wetlands could be used to treat B mine effluents in the field conditions. To this end, an experimental wetland was vegetated with common reed (Phragmites australis) and cattails (Typha latifolia), and mine effluent was moved through the wetland. The results of the present study show that B concentrations of the mine effluent decreased from 187 to 123 mg l(-1) (32% removal rate) on average. The T. latifolia individuals absorbed a total of 250 mg kg(-1) whereas P. australis in the PCW absorbed a total of 38 mg kg(-1) B during the research period.

  18. Nutrient removal as a function of benzene supply within vertical-flow constructed wetlands.

    PubMed

    Tang, Xianqiang; Scholz, Miklas; Eke, Paul Emeka; Huang, Suiliang

    2010-05-01

    The role of benzene, macrophytes and temperature in terms of nutrient removal within constructed wetlands is unknown. Therefore, a research study over approximately 30 months was conducted to assess the potential of vertical-flow constructed wetlands to treat nutrients and to examine the effect of benzene concentration, presence of Phragmites australis (Cav.) Trin. ex Steud (common reed), and temperature control on nutrient removal. Experimental wetlands removed between 72% and 90% of benzene at an influent concentration of 1000 mg L(-1). A statistical analysis indicated that benzene is linked to increased effluent chemical oxygen demand and biochemical oxygen demand concentrations. However, there was no significant relationship between benzene treatment and both nitrogen and phosphorus removal. Phragmites australis played a negligible role in organic matter (chemical oxygen demand, biochemical oxygen demand, nitrogen and phosphorus) removal. Control of temperature favoured biochemical oxygen demand removal. However, no significant difference in chemical oxygen demand, and nitrogen and phosphorus removal was detected. Only the combination of the benzene and temperature variables had a significant impact on biochemical oxygen demand removal. The effluent biochemical oxygen demand concentrations in temperature-controlled benzene treatment wetlands were much lower than those located in the natural environment. However, any other combination between benzene, P. australis and the environmental control variables had no significant effect on biochemical oxygen demand, chemical oxygen demand, or nitrogen and phosphorus removal.

  19. Contaminant removal in septage treatment with vertical flow constructed wetlands operated under batch flow conditions.

    PubMed

    Jong, Valerie Siaw Wee; Tang, Fu Ee

    2016-01-01

    Individual septic tanks are the most common means of on-site sanitation in Malaysia, but they result in a significant volume of septage. A two-staged vertical flow constructed wetlands (VFCWs) system for the treatment of septage was constructed and studied in Sarawak, Malaysia. Raw septage was treated in the first stage wetlands, and the resulting percolate was fed onto the second stage wetlands for further treatment. Here, the effects of a batch loading regime on the contaminant removal efficiency at the second stage wetlands, which included palm kernel shell within their filter substrate, are presented. The batch loading regime with pond:rest (P:R) period of 1:1, 2:2 and 3:3 (day:day) was studied. The improvement of the effluent redox condition was evident with P:R = 3:3, resulting in excellent organic matters (chemical oxygen demand and biochemical oxygen demand) and nitrogen reduction. The bed operated with P:R = 1:1 experienced constant clogging, with a water layer observed on the bed surface. For the P:R = 3:3 regime, the dissolved oxygen profile was not found to decay drastically after 24 hours of ponding, suggesting that the biodegradation mainly occurred during the first day. The study results indicate that a suitable application regime with an adequate rest period is important in VFCWs to ensure efficient operation.

  20. Evaluation of evapotranspiration in small on-site HSF constructed wetlands.

    PubMed

    Papaevangelou, Vassiliki A; Gikas, Georgios D; Tsihrintzis, Vassilios A

    2012-01-01

    Experimental results on evapotranspiration (ET), relevant to small on-site facilities are presented, derived from one-year controlled experiments in five pilot-scale horizontal subsurface flow (HSF) constructed wetlands (CW) used as lysimeters. The CW units operated in Northern Greece. They were rectangular tanks made of steel, with dimensions 3m long, 0.75m wide and 1m deep. Three different porous media were used, i.e., medium gravel, fine gravel and cobbles. Two plants were used, namely common reed (R, Phragmites australis) and cattails (C, Typha latifolia). One unit was unplanted. ET was estimated based on the water budget method. Conclusions were drawn on its relation to season and vegetation density. Furthermore, Pearson correlation coefficient analysis identified the main factors affecting wetland plant ET. Seven well-known ET empirical methods were applied to estimate ET using the measured meteorological and wetland data. ET estimated by the empirical methods were multiplied with appropriate correction coefficients to match measured ET, providing this way appropriate plant coefficient (K(c)) values, and equations for predicting HSF CW evapotranspiration. The suitability of these methods for the particular constructed wetland type is discussed through comparison with the measured data. The Blaney-Criddle method was found as best. Furthermore, stepwise multiple linear regression analysis was used with the measured ET and meteorological data to produce simple empirical equations to predict ET rates according to meteorological factors, plant and substrate material.

  1. Plant Litter Submergence Affects the Water Quality of a Constructed Wetland

    PubMed Central

    Cui, Lijuan; Li, Wei; Zhang, Xiaodong; Zhou, Jian; Yu, Fei-Hai; Prinzing, Andreas

    2017-01-01

    Plant litter is an indispensable component of constructed wetlands, but how the submergence of plant litter affects their ecosystem functions and services, such as water purification, is still unclear. Moreover, it is also unclear whether the effects of plant litter submergence depend on other factors such as the duration of litter submergence, water source or litter species identity. Here we conducted a greenhouse experiment by submerging the litter of 7 wetland plant species into three types of water substrates and monitoring changes in water nutrient concentrations. Litter submergence affected water quality positively via decreasing the concentration of nitrate nitrogen and negatively via increasing the concentrations of total nitrogen, ammonium nitrogen and total phosphorus. The effects of litter submergence depended on the duration of litter submergence, the water source, the litter species identity, and the plant life form. Different plant species had different effects on the water nutrient concentrations during litter submergence, and the effects of floating plants might be more negative than that of emergent plants. These results are novel evidence of how the submergence of different plant (life form) litter may affect the purification function of constructed wetlands. For water at low eutrophication levels, submerging a relative small amount of plant litter might improve water quality, via benefiting the denitrification process in water. These findings emphasized the management of floating plant litter (a potential removal) during the maintenance of human-controlled wetland ecosystems and provided a potential tool to improve the water quality of constructed wetlands via submerging plant litter of different types. PMID:28129405

  2. [Removal nitrogen of integrated vertical-flow constructed wetland under aeration condition].

    PubMed

    Tao, Min; He, Feng; Xu, Dong; Zhou, Qiao-Hong; Liang, Wei; Chen, Shui-Ping; Wu, Zhen-Bin

    2011-03-01

    Oxygen is an important limit factor of nitrogen removal in constructed wetlands, so it is the key point for improving nitrogen removal efficiency of constructed wetlands that the optimization of oxygen distribution within wetlands. Therefore, oxygen status, nitrogen removal and purification mechanism of integrated vertical-flow constructed wetland (IVCW) under aeration condition in summer and winter have been studied. The results showed that both oxygen levels and aerobic zones were increased in the wetland substrates. The area of oxic zone I (expressing with depth) extended from 22 cm, 17 cm to 53 cm, 44 cm, in summer and winter, respectively. The electric potential (Eh) profiling demonstrated that artificial aeration maintained the pattern of sequential oxic-anoxic-oxic (O-A-O) redox zones within the aerated IVCW in winter, while only two oxic-anoxic (O-A) zones were present inside the non-aerated IVCW in the cold season. The decomposition of organic matter and nitrification were obviously enhanced by artificial aeration since the removal efficiency of COD, TN and NH4(+) -N were increased by 12.2%, 6.9% and 15.1% in winter, respectively. There was no significant accumulation of NO3(-) -N in the effluent with an aeration cycle of 8 h on and 16 h off in this experiment. Moreover, we found that oxic zone I was the main region of pollutants removal in IVCW system, and artificial aeration mainly acted to enhance the purification capacity of this oxic zone in the aerated IVCW. These results suggest that aeration is important for optimization and application of IVCW system.

  3. Planting richness affects the recovery of vegetation and soil processes in constructed wetlands following disturbance.

    PubMed

    Means, Mary M; Ahn, Changwoo; Noe, Gregory B

    2017-02-01

    The resilience of constructed wetland ecosystems to severe disturbance, such as a mass herbivory eat-out or soil disturbance, remains poorly understood. In this study, we use a controlled mesocosm experiment to examine how original planting diversity affects the ability of constructed freshwater wetlands to recover structurally and functionally after a disturbance (i.e., aboveground harvesting and soil coring). We assessed if the planting richness of macrophyte species influences recovery of constructed wetlands one year after a disturbance. Mesocosms were planted in richness groups with various combinations of either 1, 2, 3, or 4 species (RG 1-4) to create a gradient of richness. Structural wetland traits measured include morphological regrowth of macrophytes, soil bulk density, soil moisture, soil %C, and soil %N. Functional wetland traits measured include above ground biomass production, soil potential denitrification, and soil potential microbial respiration. Total mesocosm cover increased along the gradient of plant richness (43.5% in RG 1 to 84.5% in RG 4) in the growing season after the disturbance, although not all planted individuals recovered. This was largely attributed to the dominance of the obligate annual species. The morphology of each species was affected negatively by the disturbance, producing shorter, and fewer stems than in the years prior to the disturbance, suggesting that the communities had not fully recovered one year after the disturbance. Soil characteristics were almost uniform across the planting richness gradient, but for a few exceptions (%C, C:N, and non-growing season soil moisture were higher slightly in RG 2). Denitrification potential (DEA) increased with increasing planting richness and was influenced by the abundance and quality of soil C. Increased open space in unplanted mesocosms and mesocosms with lower species richness increased labile C, leading to higher C mineralization rates.

  4. Planting richness affects the recovery of vegetation and soil processes in constructed wetlands following disturbance

    USGS Publications Warehouse

    Means, Mary M.; Ahn, Changwoo; Noe, Gregory

    2017-01-01

    The resilience of constructed wetland ecosystems to severe disturbance, such as a mass herbivory eat-out or soil disturbance, remains poorly understood. In this study, we use a controlled mesocosm experiment to examine how original planting diversity affects the ability of constructed freshwater wetlands to recover structurally and functionally after a disturbance (i.e., aboveground harvesting and soil coring). We assessed if the planting richness of macrophyte species influences recovery of constructed wetlands one year after a disturbance. Mesocosms were planted in richness groups with various combinations of either 1, 2, 3, or 4 species (RG 1–4) to create a gradient of richness. Structural wetland traits measured include morphological regrowth of macrophytes, soil bulk density, soil moisture, soil %C, and soil %N. Functional wetland traits measured include above ground biomass production, soil potential denitrification, and soil potential microbial respiration. Total mesocosm cover increased along the gradient of plant richness (43.5% in RG 1 to 84.5% in RG 4) in the growing season after the disturbance, although not all planted individuals recovered. This was largely attributed to the dominance of the obligate annual species. The morphology of each species was affected negatively by the disturbance, producing shorter, and fewer stems than in the years prior to the disturbance, suggesting that the communities had not fully recovered one year after the disturbance. Soil characteristics were almost uniform across the planting richness gradient, but for a few exceptions (%C, C:N, and non-growing season soil moisture were higher slightly in RG 2). Denitrification potential (DEA) increased with increasing planting richness and was influenced by the abundance and quality of soil C. Increased open space in unplanted mesocosms and mesocosms with lower species richness increased labile C, leading to higher C mineralization rates.

  5. Influence of substrate depth and particle size on phosphorus removal in a surface flow constructed wetland.

    PubMed

    Lijuan, Cui; Wei, Li; Jian, Zhou; Yan, Zhang; Manyin, Zhang; Yinru, Lei; Xiaoming, Kang; Xinsheng, Zhao; Xu, Pan

    2017-05-01

    Substrate adsorption is one of the main processes by which redundant phosphorus is removed from wastewater in surface flow constructed wetlands (SFCWs). The physical properties of the substrate, such as depth and particle size, will influence the amount of phosphorus adsorption. This study was carried out in a long-running intermittent inflow constructed wetland that covered a total area of 940.4 m(2) in the Shunyi District of Beijing, China. We investigated how the concentrations of four phosphorus fractions, namely calcium phosphate (CaP), iron phosphate (FeP), adsorbed phosphorus (AdsP), and organic phosphorus (OP), varied between the surface (0-10 cm) and subsurface (10-20 cm) substrate and among the different substrate particle sizes. The total phosphorus concentrations in the substrate ranged from 154.97 to 194.69 mg/kg; CaP accounted for more than 80% of the total phosphorus content. The concentrations of OP were significantly higher in the surface layer than in the subsurface layer, but the concentrations of inorganic phosphorus were not significantly different between the two layers. The CaP, AdsP, and OP adsorption capacities were greater for small-sized substrate particles than for large-sized substrate particles. The results from this study provide a theoretical basis for the construction of constructed wetlands.

  6. Early vegetational changes on a forested wetland constructed for mitigation

    USGS Publications Warehouse

    Perry, M.C.; Osenton, P.C.; Sibrel, C.B.

    1997-01-01

    Changes in vegetation were studied on 15 acres of a 35 acre forested wetland created as a mitigation site in Anne Arundel County, Maryland during 1994-96. Meter-square sampling on four different hydrologic elevations determined that grasses initially dominated the area, but decreased from 59 percent in 1994 to 51 percent in 1995 and 30 percent in 1996. Herbaceous non-grass plants (forbs) increased from 19 percent to 56 percent in the three-year period. Area with no plant cover decreased from 21 percent in 1994 to 11 percent in 1995, and 10 percent in 1996. Woody plants comprised 2 percent of the cover in 1994, increased to 4 percent in 1995, and remained at 4 percent in 1996. The increase of woody plants was mainly from natural regeneration (pioneer) plants. Monitoring of the transplanted trees and shrubs indicated 35 percent mortality and little growth of surviving plants. The pioneer woody plant forming most of the cover was black willow (Salix nigra). Differences in the vegetation were observed among the four elevations, although no differences were observed for the major vegetation classes between plots that were planted and those that were not planted with woody plants. Dominant grass species was redtop (Agrostis stolonifera), which comprised 51 percent of the cover in 1994 and 42 percent cover in 1995 and 23 percent in 1996. Other species that were common were bush clover (Lespedeza cuneata), Japanese clover (Lespedeza striata) and flat pea (Lathyrus sylvestris). All four of these dominant species were part of the original seed mixtures that were seeded on the site. A total of 134 species of plants was recorded on the site indicating a fairly diverse community for a newly established habitat.

  7. Emission of the greenhouse gases nitrous oxide and methane from constructed wetlands in europe.

    PubMed

    Søvik, A K; Augustin, J; Heikkinen, K; Huttunen, J T; Necki, J M; Karjalainen, S M; Kløve, B; Liikanen, A; Mander, U; Puustinen, M; Teiter, S; Wachniew, P

    2006-01-01

    The potential atmospheric impact of constructed wetlands (CWs) should be examined as there is a worldwide increase in the development of these systems. Fluxes of N(2)O, CH(4), and CO(2) have been measured from CWs in Estonia, Finland, Norway, and Poland during winter and summer in horizontal and vertical subsurface flow (HSSF and VSSF), free surface water (FSW), and overland and groundwater flow (OGF) wetlands. The fluxes of N(2)O-N, CH(4)-C, and CO(2)-C ranged from -2.1 to 1000, -32 to 38 000, and -840 to 93 000 mg m(-2) d(-1), respectively. Emissions of N(2)O and CH(4) were significantly higher during summer than during winter. The VSSF wetlands had the highest fluxes of N(2)O during both summer and winter. Methane emissions were highest from the FSW wetlands during wintertime. In the HSSF wetlands, the emissions of N(2)O and CH(4) were in general highest in the inlet section. The vegetated ponds in the FSW wetlands released more N(2)O than the nonvegetated ponds. The global warming potential (GWP), summarizing the mean N(2)O and CH(4) emissions, ranged from 5700 to 26000 and 830 to 5100 mg CO(2) equivalents m(-2) d(-1) for the four CW types in summer and winter, respectively. The wintertime GWP was 8.5 to 89.5% of the corresponding summertime GWP, which highlights the importance of the cold season in the annual greenhouse gas release from north temperate and boreal CWs. However, due to their generally small area North European CWs were suggested to represent only a minor source for atmospheric N(2)O and CH(4).

  8. Candidate soil indicators for monitoring the progress of constructed wetlands toward a natural state: a statistical approach

    USGS Publications Warehouse

    Stapanian, Martin A.; Adams, Jean V.; Fennessy, M. Siobhan; Mack, John; Micacchion, Mick

    2013-01-01

    A persistent question among ecologists and environmental managers is whether constructed wetlands are structurally or functionally equivalent to naturally occurring wetlands. We examined 19 variables collected from 10 constructed and nine natural emergent wetlands in Ohio, USA. Our primary objective was to identify candidate indicators of wetland class (natural or constructed), based on measurements of soil properties and an index of vegetation integrity, that can be used to track the progress of constructed wetlands toward a natural state. The method of nearest shrunken centroids was used to find a subset of variables that would serve as the best classifiers of wetland class, and error rate was calculated using a five-fold cross-validation procedure. The shrunken differences of percent total organic carbon (% TOC) and percent dry weight of the soil exhibited the greatest distances from the overall centroid. Classification based on these two variables yielded a misclassification rate of 11% based on cross-validation. Our results indicate that % TOC and percent dry weight can be used as candidate indicators of the status of emergent, constructed wetlands in Ohio and for assessing the performance of mitigation. The method of nearest shrunken centroids has excellent potential for further applications in ecology.

  9. Use of macrophyte plants, sand & gravel materials in constructed wetlands for greywater treatment

    NASA Astrophysics Data System (ADS)

    Qomariyah, S.; Ramelan, AH; Sobriyah; Setyono, P.

    2017-02-01

    Greywater discharged without any treatments into drainage channels or natural water bodies will lead to environmental degradation and health risk. Local macrophyte plants combined with natural materials of sand and gravel have been used in a system of constructed wetland for the treatment of the greywater. This paper presents the results of some studies of the system carried out in Indonesia, Thailand, and Costa Rica. The studies demonstrate the success of the constructed wetland systems in removing some pollutants of BOD, COD, TSS, pathogen, and detergent. The studies resulted in the treated water in a level of treatment that fulfils the requirement of the local standards for wastewater reuse as irrigation water, fishery, or other outdoor needs.

  10. Performance of the Iron-Caron Coupling Constructed Wetland for Rural Sewage Treatment

    NASA Astrophysics Data System (ADS)

    Xia, Ruize; Peng, Yutao; Zhong, Shan; Tu, Lijun; Xie, Yuanshan; Zhang, Lishan

    2017-01-01

    In recent years, rural decentralized sewage treatment have gained widespread attention. Although wastewater treatment facility has been developed for rural areas, most rural population are left without adequate wastewater treatment systems. In the present study, the performance of iron-carbon coupling constructed wetland system (ICCWS) and constructed wetland system (CWS) receiving synthetic domestic wastewater were compared in side-by-side trials. Studies have found that CWS filled with spherical iron-carbon packing showed better treatment efficiency than normal CWS. When the HRT is 3 days, the ICCWS have 95.8% COD and 96.6% PO4 3- removal rate, higher than 67.0% COD and 74.3% PO4 3- removal rate in CWS respectively. The use of ICCWS planted with canna and cattail proved to be efficient technology for the removal of rural wastewater pollutants.

  11. Treatment of dairy wastewater using constructed wetlands and intermittent sand filters.

    PubMed

    Healy, M G; Rodgers, M; Mulqueen, J

    2007-09-01

    In Ireland, the most common method of disposal of dairy parlour washings is by land spreading. This treatment method has numerous problems, namely high-labour requirements and the potential for eutrophication of surface and ground waters. Constructed wetlands are commonly used for treatment of secondary municipal wastewaters and they have been gaining popularity for treatment of agricultural wastewaters in Ireland. Intermittent sand filtration may offer an alternative to traditional treatment methods. As well as providing comparable treatment performance, they also have a smaller footprint, due to the substantially higher organic loading rates that may be applied to their surfaces. This paper discusses the performance and design criteria of constructed wetlands for the treatment of domestic and agricultural wastewater, and sand filters for the treatment of domestic wastewater. It also proposes sand filtration as an alternative treatment mechanism for agricultural wastewater and suggests design guidelines.

  12. Study of oyster shell as a potential substrate for constructed wetlands.

    PubMed

    Wang, Zhen; Dong, Jian; Liu, Lin; Zhu, Gefu; Liu, Chaoxiang

    2013-01-01

    We tested the suitability of oyster shell (OS) as a substrate for phosphorus removal in constructed wetlands (CWs) treating swine wastewater. OS is proven to have a significant phosphorus adsorption capacity; significant phosphorus removal was achieved in vertical subsurface flow constructed wetlands (VSSFs) that were filled with OS and used to treat swine wastewater. In the VSSF system, OS adsorption and precipitation played the greatest role in phosphorus removal, and the phosphorus distribution in the substrate layers was attributed to the vertical flow state of wastewater in the system. Ca-P was the predominant form of phosphorus in the system. Overall, the study results showed that OS could be used for phosphorus removal in CWs. OS also allowed for reuse of a waste substance, making the overall system more environmentally friendly.

  13. Constructed wetlands for environmental pollution control: a review of developments, research and practice in Ireland.

    PubMed

    Babatunde, A O; Zhao, Y Q; O'Neill, M; O'Sullivan, B

    2008-01-01

    For the purpose of synthesizing a compendium of efforts aimed at environmental pollution control through the use of constructed wetlands systems (CWs) in Ireland, a detailed review of CWs was undertaken. Emphasis was placed on the diverse range of development, practice and researches on CWs technology, placing them in the overall context of the need for low-cost and sustainable wastewater treatment systems. The potential use of CWs in protecting estuarine quality within the current legislative framework is considered, as well as the emerging concept of integrated constructed wetlands (ICWs). In addition, an assessment of the efficiency of CWs in operation in Ireland towards abating environmental pollution was done, and compared with CWs operating in other European countries. The need for sufficient and appropriate data to assist in further development of CWs and modelling studies, and instilling confidence in the public is also highlighted.

  14. Improving the treatment efficiency of constructed wetlands with zeolite-containing filter sands.

    PubMed

    Bruch, Ingo; Fritsche, Johannes; Bänninger, Dominik; Alewell, Ulrike; Sendelov, Michael; Hürlimann, Heinz; Hasselbach, Ralf; Alewell, Christine

    2011-01-01

    In this study the physical and chemical properties of three different lava sands used in constructed wetlands for municipal wastewater treatment were investigated. The aim was to identify those properties and mechanisms that render lava sands as highly efficient filter media which could substitute conventional, fluviatile sands. It was shown that although lava sands per se may be suitable filter materials, the presence of zeolite minerals within the lava sands enhances the purification efficiency tremendously. Zeolites not only increase the sorption capacity, but even more important, they are able to absorb water in large amounts, which in turn leads to stronger swelling. The latter reduces hydrological conductivity considerably, resulting in a longer contact time to eliminate pollutants. A simple mineralogical survey of filter materials for the presence of zeolites may render many installations of constructed wetlands successful. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. Model-based design of horizontal subsurface flow constructed treatment wetlands: a review.

    PubMed

    Rousseau, Diederik P L; Vanrolleghem, Peter A; De Pauw, Niels

    2004-03-01

    The increasing application of constructed wetlands for wastewater treatment coupled with increasingly strict water quality standards is an ever growing incentive for the development of better process design tools. This paper reviews design models for horizontal subsurface flow constructed treatment wetlands, ranging from simple rules of thumb and regression equations, to the well-known first-order k-C* models, Monod-type equations and more complex dynamic, compartmental models. Especially highlighted in this review are the model constraints and parameter uncertainty. A case study has been used to demonstrate the model output variability and to unravel whether or not more complex but also less manageable models offer a significant advantage to the designer.

  16. Assessment of the microbial community in a constructed wetland that receives acid coal mine drainage

    SciTech Connect

    Nicomrat, D.; Dick, W.A.; Tuovinen, O.H.

    2006-01-15

    Constructed wetlands are used to treat acid drainage from surface or underground coal mines. However, little is known about the microbial communities in the receiving wetland cells. The purpose of this work was to characterize the microbial population present in a wetland that was receiving acid coal mine drainage (AMD). Samples were collected from the oxic sediment zone of a constructed wetland cell in southeastern Ohio that was treating acid drainage from an underground coal mine seep. Samples comprised Fe(Ill) precipitates and were pretreated with ammonium oxalate to remove interfering iron, and the DNA was extracted and purified by agarose gel electrophoresis prior to amplification of portions of the 16S rRNA gene. Amplified products were separated by denaturing gradient gel electrophoresis and DNA from seven distinct bands was excised from the gel and sequenced. The sequences were matched to sequences in the GenBank bacterial 16S rDNA database. The DNA in two of the bands yielded matches with Acidithiobacillus ferrooxidans and the DNA in each of the remaining five bands was consistent with one of the following microorganisms: Acidithiobacillus thiooxidans, strain TRA3-20 (a eubacterium), strain BEN-4 (an arsenite-oxidizing bacterium), an Alcaligenes sp., and a Bordetella sp. Low bacterial diversity in these samples reflects the highly inorganic nature of the oxic sediment layer where high abundance of iron- and sulfur-oxidizing bacteria would be expected. The results we obtained by molecular methods supported our findings, obtained using culture methods, that the dominant microbial species in an acid receiving, oxic wetland are A. thiooxidans and A. ferrooxidans.

  17. Nutrient removal and bacterial communities in swine wastewater lagoon and constructed wetlands.

    PubMed

    Dong, Xiuli; Reddy, Gudigopuram B

    2010-10-01

    Surface constructed wetlands, including marsh-pond-marsh (MPM) and continuous marsh (CtM) were used to treat swine wastewater in this study. The objectives of this research were to evaluate the surface constructed wetland effects on swine wastewater treatment, and to investigate bacterial distribution shifts along treatment flows. Water quality parameters and bacterial community diversity were analyzed in each section of the entire wastewater treatment system, which was from the anaerobic lagoons (La1 and La2), through the wetlands, to the storage lagoon (La3) receiving wetland effluent. The results of water quality parameters demonstrated that the concentration of TKN, NH4+, o-PO4(3-), and COD decreased significantly (P<0.05) from La1 to La3. If ammonia volatilization is integrated for N removal in MPM wetland cell, then there was no difference between MPM and CtM cells. The total bacterial community in each section of the system was examined by using PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) technique. Our finding disclosed that the bacterial communities in different sections of the wastewater treatment system showed high diversities. The bacterial community compositions shifted gradually with the wastewater treatment procedure. Principal component analysis (PCA) and redundancy analysis (RDA) confirmed that the bacterium species distribution was strongly related to the COD, o-PO4(3-), and TKN concentrations, whereas moderately related to the NH4+ concentration. Flavobacterium sp. and Methylomonas sp. were detected according to partial 16S rRNA gene sequences.

  18. Assessment of the microbial community in a constructed wetland that receives acid coal mine drainage.

    PubMed

    Nicomrat, Duongruitai; Dick, Warren A; Tuovinen, Olli H

    2006-01-01

    Constructed wetlands are used to treat acid drainage from surface or underground coal mines. However, little is known about the microbial communities in the receiving wetland cells. The purpose of this work was to characterize the microbial population present in a wetland that was receiving acid coal mine drainage (AMD). Samples were collected from the oxic sediment zone of a constructed wetland cell in southeastern Ohio that was treating acid drainage from an underground coal mine seep. Samples comprised Fe(III) precipitates and were pretreated with ammonium oxalate to remove interfering iron, and the DNA was extracted and purified by agarose gel electrophoresis prior to amplification of portions of the 16S rRNA gene. Amplified products were separated by denaturing gradient gel electrophoresis and DNA from seven distinct bands was excised from the gel and sequenced. The sequences were matched to sequences in the GenBank bacterial 16S rDNA database. The DNA in two of the bands yielded matches with Acidithiobacillus ferrooxidans and the DNA in each of the remaining five bands was consistent with one of the following microorganisms: Acidithiobacillus thiooxidans, strain TRA3-20 (a eubacterium), strain BEN-4 (an arsenite-oxidizing bacterium), an Alcaligenes sp., and a Bordetella sp. Low bacterial diversity in these samples reflects the highly inorganic nature of the oxic sediment layer where high abundance of iron- and sulfur-oxidizing bacteria would be expected. The results we obtained by molecular methods supported our findings, obtained using culture methods, that the dominant microbial species in an acid receiving, oxic wetland are A. thiooxidans and A. ferrooxidans.

  19. Water balance: case study of a constructed wetland as part of the bio-ecological drainage system (BIOECODS).

    PubMed

    Ayub, Khairul Rahmah; Zakaria, Nor Azazi; Abdullah, Rozi; Ramli, Rosmaliza

    2010-01-01

    The Bio-ecological Drainage System, or BIOECODS, is an urban drainage system located at the Engineering Campus, Universiti Sains Malaysia. It consists of a constructed wetland as a part of the urban drainage system to carry storm water in a closed system. In this closed system, the constructed wetland was designed particularly for further treatment of storm water. For the purpose of studying the water balance of the constructed wetland, data collection was carried out for two years (2007 and 2009). The results show that the constructed wetland has a consistent volume of water storage compared to the outflow for both years with correlation coefficients (R(2)) of 0.99 in 2007 and 0.86 in 2009.

  20. Influence of substrate water saturation on pesticide dissipation in constructed wetlands.

    PubMed

    Vallée, Romain; Dousset, Sylvie; Billet, David

    2016-01-01

    Constructed wetlands are an effective and practical option for removing pesticide pollution from runoff or subsurface drainage water. The objective of this study was to assess the efficiencies of a ditch with a bundle of straw placed in its centre and a vegetated pond installed in grass cover bands at downstream of a drained plot. The dissipation rates of three herbicides and three fungicides were monitored on four substrates commonly found in constructed wetlands (two soils, sediment and straw). The influence of water content was determined in a sequence of three steps (flooded-unsaturated-flooded) over 120 days. The pesticide dissipation rates observed during the 120 days of incubation ranged from 1.4 to 100%. Isoproturon and 2,4-MCPA (MCPA) showed the highest dissipation rates, which ranged from 61.0 to 100% of the applied quantities during the 120 days of incubation. In contrast, boscalid and tebuconazole showed the lowest dissipation rates, which ranged from 1.4 to 43.9% of the applied quantities during the 120 days of incubation. The estimated DT50 values ranged from 20.5 days to more than 1 year and were influenced by the substrate water content. The soil and straw substrates had the lowest DT50 values during the unsaturated conditions, whereas the sediments had the lowest DT50 values during the flooded conditions. These results could be explained by an adaptation of microbial communities to their environmental conditions. Thus, the most favourable conditions of dissipation for soils and straw are observable when the drainage ceases (spring and summer). However, favourable conditions occur all year for the sediments, except when the constructed wetlands are dry. The results suggest that the dissipation of pesticides in constructed wetlands contributes to the long-term effectiveness of these buffer zones for reducing water pollution.

  1. Simulation of the treatment performance of outdoor subsurface flow constructed wetlands in temperate climates.

    PubMed

    Langergraber, Günter

    2007-07-15

    Numerical models are a means to increase the understanding of the processes occurring in the "black box" constructed wetland. Once reliable models for constructed wetlands are available they can be also used for evaluating and improving existing design criteria. The paper shows simulation results for outdoor experimental subsurface vertical flow constructed wetlands using CW2D, a multi-component reactive transport module developed to simulate transport and reactions of the organic matter, nitrogen and phosphorus in subsurface flow constructed wetlands. The surface area of the experimental vertical flow bed was 20 m(2). The organic load applied was 27 g COD m(-2) d(-1) (corresponding to a specific surface area of 3 m(2) per person). The aim of the work is to calibrate the model for temperature dependency that has been implemented in CW2D. Water temperature during the investigation period varied between 4 degrees C and 18 degrees C. The measured effluent concentrations during summer could be simulated using the standard CW2D parameter set when the flow model was calibrated well. However, the increasing effluent concentrations at low temperatures could not be simulated with the standard CW2D parameter set where temperature dependencies are considered only for maximum growth, decay, and hydrolysis rates. By introducing temperature dependencies for half-saturation constants for the hydrolysis and nitrification processes it was possible to simulate the observed behaviour. The work presented is a step on the way to validate the CW2D module. Model validation is a necessary step before numerical simulation can be finally used in practice, e.g. for checking existing design guidelines.

  2. Manufactured Soil Field Demonstration for Constructing Wetlands to Treat Acid Mine Drainage on Abandoned Minelands

    DTIC Science & Technology

    2007-11-01

    constructing the wetlands including dredged material, residual waste paper fiber, sawdust, mush- room compost , cow manure, processed cow manure, and...Bony + Waste Paper Fiber + Mushroom Compost + BionsoilTM The RSMT procedures (Sturgis and Lee 1999) were applied in a randomized complete block design...than 100 percent Bony, 100 percent Donora, 3BD, and the 4 ERDC TN-DOER-D9 November 2007 fertile commercial potting soil. Blend 1BD was selected for

  3. Landfill leachate treatment by an experimental subsurface flow constructed wetland in tropical climate countries.

    PubMed

    Ujang, Z; Soedjono, E; Salim, M R; Shutes, R B

    2005-01-01

    Municipal leachate was treated in an experimental unit of constructed wetlands of subsurface flow type. The parameters studied were organics (BOD and COD), solids and heavy metals (Zn, Ni, Cu, Cr and Pb). Using two types of emergent plants of Scirpus globulosus and Eriocaulon sexangulare, more than 80% removal was achieved for all the parameters. E. sexangulare removed organics and heavy metals better than Scirpus globulosus. A higher concentration of heavy metals in the influent did not change the removal efficiency.

  4. Landfill leachate treatment using sub-surface flow constructed wetland by Cyperus haspan.

    PubMed

    Akinbile, Christopher O; Yusoff, Mohd Suffian; Ahmad Zuki, A Z

    2012-07-01

    Performance evaluation of pilot scale sub-surface constructed wetlands was carried out in treating leachate from Pulau Burung Sanitary Landfill (PBSL). The constructed wetland was planted with Cyperus haspan with sand and gravel used as substrate media. The experiment was operated for three weeks retention time and during the experimentation, the influent and effluent samples were tested for its pH, turbidity, color, total suspended solid (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), ammonia nitrogen (NH(3)-N), Total phosphorus (TP), total nitrogen (TN) and also for heavy metals such as iron (Fe), magnesium (Mg), manganese (Mn) and zinc (Zn) concentrations. The results showed that the constructed wetlands with C. haspan were capable of removing 7.2-12.4% of pH, 39.3-86.6% of turbidity, 63.5-86.6% of color, 59.7-98.8% of TSS, 39.2-91.8% of COD, 60.8-78.7% of BOD(5), 29.8-53.8% of NH(3)-N, 59.8-99.7% of TP, 33.8-67.0% of TN, 34.9-59.0% of Fe, 29.0-75.0% of Mg, 51.2-70.5% of Mn, and 75.9-89.4% of Zn. The significance of removal was manifested in the quality of the effluent obtained at the end of the study. High removal efficiencies in the study proved that leachate could be treated effectively using subsurface constructed wetlands with C. haspan plant. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Investigations of subsurface flow constructed wetlands and associated geomaterial resources in the Akumal and Reforma regions, Quintana Roo, Mexico

    NASA Astrophysics Data System (ADS)

    Krekeler, Mark P. S.; Probst, Pete; Samsonov, Misha; Tselepis, Cynthia M.; Bates, William; Kearns, Lance E.; Maynard, J. Barry

    2007-12-01

    Subsurface flow constructed wetlands in the village of Akumal, Quintana Roo, Mexico were surveyed to determine the general status of the wetland systems and provide baseline information for long term monitoring and further study. Twenty subsurface flow wetlands were surveyed and common problems observed in the systems were overloading, poor plant cover, odor, and no secondary containment. Bulk mineral composition of aggregate from two subsurface flow constructed wetlands was determined to consist solely of calcite using bulk powder X-ray diffraction. Some soil structure is developed in the aggregate and aggregate levels in wetlands drop at an estimated rate between 3 and 10 cm/year for overloaded wetlands owing to dissolution. Mineral composition from fresh aggregate samples commonly is a mixture of calcite and aragonite. Trace amounts of Pb, Zn, Co, and Cr were observed in fresh aggregate. Coefficients of permeability ( k) varied from 0.006 to 0.027 cm/s with an average values being 0.016 cm/s. Grain size analysis of fresh aggregate samples indicates there are unimodal and multimodal size distributions in the samples with modes in the coarse and fine sand being common. Investigations of other geologic media from the Reforma region indicate that a dolomite with minor amounts of Fe-oxide and palygorskite is abundant and may be a better aggregate source that the current materials used. A Ca-montmorillonite bed was identified in the Reforma region as well and this unit is suitable to serve as a clay liner to prevent leaks for new and existing wetland systems. These newly discovered geologic resources should aid in the improvement of subsurface flow constructed wetlands in the region. Although problems do exist in these wetlands with respect to design, these systems represent a successful implementation of constructed wetlands at a community level in developing regions.

  6. Using cerium anomaly as an indicator of redox reactions in constructed wetland

    NASA Astrophysics Data System (ADS)

    Liang, R.

    2013-12-01

    The study area, Chiayi County located in southern Taiwan, has highly developed livestock. The surface water has very low dissolved oxygen and high NH4. Under the situation, constructed wetland becomes the most effective and economic choice to treat the wastewater in the natural waterways. Hebao Island free surface constructed wetland started to operate in late 2006. It covers an area of 0.28 km2 and is subdivided into 3 major cells, which are sedimentation cell, 1st aeration cell with rooted plants and 2nd aeration cell with float plants. The water depth of cells ranges from 0.6 m to 1.2 m. The total hydraulic retention time is about a half day. In this study, the water samples were sequentially collected along the flow path. The results of hydrochemical analysis show that the untreated inflow water can be characterized with enriched NH4 (11 ppm), sulfate (6 ppm) and arsenic (50 ppb). The removal efficiency of NH4 in the first two cells is <15%. However, the efficiency dramatically increases in the 2nd aeration cell, which is over 90%. Simultaneously, almost all of the hydrochemical properties, including EC, Ca, Mg, As Fe, Mn and other heavy metals, decrease while dissolve oxygen increases close to saturated level and aluminum is almost doubled in the exit of constructed wetland. However, the removal of sulfate and phosphate is very weak. It is worth to note that arsenic is still higher than the permissible limits recommended by WHO (10 ppb). The wetland operation should be tuned to take more arsenic away in the future. As demonstrated in the above, oxidation reaction is the most dominant mechanism to remove pollutants from the wastewater; therefore, dissolved oxygen is traditionally considered as an important indicator to evaluate the operation efficiency of wetland. However, it would need longer time to achieve equilibrium state of redox reaction involving dissolved oxygen due to the slower reaction rate. For example, the input water in this study has fairly high

  7. A System Dynamics Approach to Modelling the Degradation of Biochemical Oxygen Demand in A Constructed Wetland Receiving Stormwater Runoff

    DTIC Science & Technology

    1995-12-01

    conventional treatment plants " are: "Constructed wetland systems (1) are relatively inexpensive to construct and operate; (2) are easy to maintain; (3) provide... macrophytes are divided into free floating and rooted forms. The rooted forms are further subdivided into emergent , floating and submerged classes...to state that "the removal of larger particles protects one of the key roles of emergent aquatic macrophytes in the wetlands which is the provision

  8. [Removal and accumulation of the tetracycline resistance gene in vertical flow constructed wetland].

    PubMed

    Zheng, Jia-Yu; Liu, Lin; Gao, Da-Wen; Liu, Chao-Xiang

    2013-08-01

    This paper investigated the efficiency and accumulation of vertical flow constructed wetland on removing tetracycline resistance (tet) genes (tetM, tetO, and tetW) from swine wastewater. The result indicated that all three tet genes were detected in raw wastewater, average absolute abundances of tetW, tetM, and tetO were 1.07 x 10(10), 4.03 x 10(10) and 4.92 x 10(10) gene copies per litre, respectively. Vertical flow constructed wetland could significantly reduce the content of wastewater antibiotics resistance genes, and average elimination rates were 95.73%, 92.21% and 95.05%, respectively. Compare to the content of antibiotics resistance genes in unpolluted soil, the content of that in soil of the system had an obvious increase at the end stage of this study. Meanwhile, absolute abundances and relative abundances of three tet genes in surface layer of soil were higher than that in basement soil. The control condition and structure of construct wetlands would affect the accumulation of tetracycline resistance genes in the system.

  9. Bioremediation of endosulfan in laboratory-scale constructed wetlands: effect of bioaugmentation and biostimulation.

    PubMed

    Zhao, Congcong; Xie, HuiJun; Mu, Yang; Xu, Xiaoli; Zhang, Jian; Liu, Cui; Liang, Shuang; Ngo, Huu Hao; Guo, Wenshan; Xu, Jingtao; Wang, Qian

    2014-11-01

    Bioremediation is widely used in organic pollutants disposal. However, very little has been known on its application in constructed wetlands contaminated with organochlorine pesticide, endosulfan in particular. To evaluate the effect of bioremediation on endosulfan removal and clarify the fate, bioaugmentation and biostimulation were studied in laboratory-scale vertical-flow constructed wetlands. After 20 days' experiment, endosulfan isomers removal efficiencies were increased to 89.24-97.62 % through bioremediation. In bacteria bioaugmentation (E-in) and sucrose biostimulation (E-C), peak concentrations of endosulfan in sediment were reduced by 31.02-76.77 %, and plant absorption were 347.45-576.65 μg kg(-1). By contrast, plant absorption in KH2PO4 biostimulation (E-P) was increased to 811.64 and 1,067.68 μg kg(-1). Degradation process was probably promoted in E-in and E-C, while plant absorption was enhanced in E-P. Consequently, E-in and E-C were effective for endosulfan removal in constructed wetlands, while adding KH2PO4 had potential to cause air pollution. Additionally, combined bioremediation was not recommended.

  10. Removal of N, P, BOD5, and coliform in pilot-scale constructed wetland systems.

    PubMed

    Jin, Guang; Kelley, Tim; Freeman, Mike; Callahan, Mike

    2002-01-01

    Pilot-scale surface-flow (SF), subsurface-flow (SSF), and floating aquatic plant (FAP) constructed wetland system designs were installed and evaluated to determine the effectiveness of constructed wetlands to treat tertiary effluent wastewater in a Midwestern U.S. climate (central Illinois). Average ammonia-nitrogen (N) concentrations decreased approximately 50% in the SSF system design, suggesting that this design had the highest nitrification rate. Nitrate-N concentrations decreased by over 60% in the FAP system design, possibly due to dissimilatory reduction or plant uptake. Total phosphorus (P) concentration reductions of 25 to 40% were observed in all three system designs. Five-day biochemical oxygen demand (BOD5) and dissolved oxygen (DO) results suggested that biodegradation was highest in the SSF system design and lowest in the FAP system design. Greater than 90% concentration reductions of total coliform and E. coli recovered were also observed following treatment in all three system designs. The FAP system design appeared to yield the highest concentration reduction efficiency for E. coli, possibly due to increased sunlight and related bacteriocidal ultraviolet light exposure. Ongoing experiments will test regularly for a variety of vegetative, water quality, and biological conditions for longer time periods in order to gain a better understanding of the pilot constructed wetland system design kinetics.

  11. The integration of constructed wetlands into a treatment system for airport runoff.

    PubMed

    Revitt, D M; Worral, P; Brewer, D

    2001-01-01

    A new surface runoff treatment system has been designed for London Heathrow Airport, which incorporates separate floating constructed wetlands or reedbeds and sub-surface flow constructed wetlands as major pollutant removal systems. The primary requirement of the newly developed treatment system is to control the concentrations of glycols following their use as de-icers and anti-icers within the airport. The ability of reedbeds to contribute to this treatment role was fully tested through pilot scale, on-site experiments over a 2 year period. The average reductions in runoff BOD concentrations achieved by pilot scale surface flow and sub-surface flow reedbeds were 30.9% and 32.9%, respectively. The corresponding average glycol removal efficiencies were 54.2% and 78.3%, following shock dosing inputs. These treatment performances are used to predict the required full scale constructed wetland surface areas needed to attain the desired effluent water quality. The treatment system also incorporates aeration, storage and, combined with reedbed technology, has been designed to reduce a mixed inlet BOD concentration of 240 mg/l to less than 40 mg/l for water temperatures varying between 6 degrees C and 20 degrees C.

  12. Estrogen degradation and sorption onto colloids in a constructed wetland with different hydraulic retention times.

    PubMed

    Chen, Ting-Chien; Yeh, Kuei-Jyum C; Kuo, Wen-Chien; Chao, How-Ran; Sheu, Shyang-Chwen

    2014-07-30

    Endocrine disrupting compounds are a global concern, owing to their interference with the endocrine system of wildlife. In particular, natural estrogens at concentrations as low as ng/L level can interrupt the endocrine system of many organisms. A constructed wetland is an effective means of removing the residual levels of estrogen. This study investigates the estrogen degradation and sorption on colloids in a constructed wetland at hydraulic retention times (HRTs) of 27.5, 45.9, and 137.5h. Three natural estrogens (i.e. estrone (E1), 17β-estradiol (E2), and estriol (E3)) are analyzed with liquid chromatography/tandem mass spectrometry. At HRT=27.5h, no degradation occurs; at HRT=45.9h, the degradation rates are 0-46.2%; and at HRT=137.5h, the degradation rates are 40-84.3%. Additionally, estrogen sorption coefficients (logKCOC values) range from 3.37 to 4.89. Average logKCOC values are 4.08±0.33, 4.04±0.34, and 4.11±0.28 for E1, E2, and E3, respectively. At different HRTs, values of logKCOC increase with an increasing HRT. Analytical results indicate that constructed wetlands can remove residual natural estrogens. With an increasing HRT, the estrogen degradation rate increases as well as the estrogen sorption on colloids.

  13. Performance and cost comparison of a FWS and a VSF constructed wetland system.

    PubMed

    Tsihrintzis, V A; Akratos, C S; Gikas, G D; Karamouzis, D; Angelakis, A N

    2007-06-01

    Two constructed wetland systems, treating domestic wastewater, are compared in terms of performance and costs. One is a free water surface (FWS) wetland system located in Pompia, Crete, south Greece, and the other one is a vertical subsurface flow (VSF) wetland system located in Comati, Chalkidiki, north Greece. The FWS system is designed for 1200 p.e. Its construction cost was Euro 305,000, and the capital, operation and maintenance cost was Euro 22.07 p.e.(-1) yr(-1) or Euro 0.50 m(-3) of influent. The VSF system is designed for 1000 p.e. Its construction cost was Euro 410,850, and the capital, operation and maintenance cost was Euro 36.81 p.e.(-1) yr(-1) or Euro 0.56 m(-3) of influent. Both systems achieved high removal rates for BOD5, COD, TSS, TKN, phosphorus, TC, and FC, which makes them ideal for small communities in the Mediterranean region.

  14. Performance and bacterial community structure of a 10-years old constructed mangrove wetland.

    PubMed

    Tian, Tingting; Tam, Nora F Y; Zan, Qijie; Cheung, S G; Shin, Paul K S; Wong, Y S; Zhang, Li; Chen, Zhanghe

    2017-07-12

    Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate. Denaturing gradient gel electrophoresis showed that microbial diversity in planted substrate was significantly lower than that in unplanted one. The bacteria in substrates, irrespective to belts, were phylogenetically related to Proteobacteria (most dominant), Acidobacteria, Firmicutes, Nitrospirae, Gemmatimonadetes, Chloroflexi and Cyanobacteria. The steady performance of this 10-year old constructed mangrove wetland was affected by the abundance and diversity of bacterial community in substrate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Water Purification Characteristic of the Actual Constructed Wetland with Carex dispalata in a Cold Area

    NASA Astrophysics Data System (ADS)

    Tsuji, Morio; Yamada, Kazuhiro; Hiratsuka, Akira; Tsukada, Hiroko

    Carex dispalata, a native plant species applied in cold districts for water purification in constructed wetlands, has useful characteristics for landscape creation and maintenance. In this study, seasonal differences in purification ability were verified, along with comparison of frozen and non-frozen periods' performance. A wetland area was constructed using a “hydroponics method” and a “coir fiber based method”. Results show that the removal rates of BOD, SS, and Chl-a were high. On this constructed wetland reduces organic pollution, mainly phytoplankton, but the removal of nitrogen and phosphorus was insufficient. The respective mean values of influent and treated water during three years were 26.6 mg/L and 12.2 mg/L for BOD, and 27.9 mg/L and 7.5 mg/L for SS. The mean value of the BOD removal rate for the non-frozen period was 2.99 g/m2/d that for the frozen period was 1.86 g/m2/d. The removal rate followed the rise of the BOD load rate. The removal rate limits were about 4 g/m2/d during the frozen period and 15 g/m2/d during the non-frozen period. For operations, energy was unnecessary. The required working hours were about 20 h annually for all maintenance and management during operations.

  16. Intensified nitrogen and phosphorus removal in a novel electrolysis-integrated tidal flow constructed wetland system.

    PubMed

    Ju, Xinxin; Wu, Shubiao; Zhang, Yansheng; Dong, Renjie

    2014-08-01

    A novel electrolysis-integrated tidal flow constructed wetland (CW) system was developed in this study. The dynamics of intensified nitrogen and phosphorus removal and that of hydrogen sulphide control were evaluated. Ammonium removal of up to 80% was achieved with an inflow concentration of 60 mg/L in wetland systems with and without electrolysis integration. Effluent nitrate concentration decreased from 2 mg/L to less than 0.5 mg/L with the decrease in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2) in the electrolysis-integrated wetland system, thus indicating that the current intensity of electrolysis plays an important role in nitrogen transformations. Phosphorus removal was significantly enhanced, exceeding 95% in the electrolysis-integrated CW system because of the in-situ formation of a ferric iron coagulant through the electro-dissolution of a sacrificial iron anode. Moreover, the electrolyzed wetland system effectively inhibits sulphide accumulation as a result of a sulphide precipitation coupled with ferrous-iron electro-dissolution and/or an inhibition of bacterial sulphate reduction under increased aerobic conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Passive treatment using coal combustion products: An innovative vertical flow constructed wetland field study

    SciTech Connect

    Nairn, R.W.; Mercer, M.N.; Everett, J.W.

    1999-07-01

    Designs of constructed wetlands for acid mine drainage (AMD) treatment have evolved substantially during the past decade. Current research focuses on the study of vertical-flow treatment systems containing labile organic substrates. Also known as successive alkalinity producing systems (SAPS), these systems emphasize contact of acidic waters with the substrate, thus maximizing biological alkalinity generation, via bacterial sulfate reduction, and abiotic alkalinity generation via carbonate dissolution processes. in this study, a coal combustion product (CCP) was utilized to generate supplementary alkalinity in addition to that provided by traditional substrate materials of spent mushroom substrate (SMS) and high CaCO{sub 3} content limestone. Although limestone is commonly utilized for abiotic alkalinity generation in AMC treatment wetlands, CCPs are not. The preliminary effectiveness of this innovative vertical flow passive treatment system was evaluated during the initial year of operation. The wetlands are successfully retaining iron, aluminum and manganese and are increasing pH, alkalinity, dissolved oxygen (from ,1.0 to >13 mg/L, due to biological productivity), and calcium (from 31 to 385 mg/L, presumably due to limestone and hydrated fly ash dissolution). No hydraulic conductivity problems have been encountered in the initial year of operation. CCPs may offer an attractive alternative, or supplementary, alkalinity generating source for AMD treatment wetlands.

  18. [Pilot-scale comparison research of different constructed wetland types to treat eutrophic lake water].

    PubMed

    Nie, Zhi-Dan; Nian, Yue-Gang; Jin, Xiang-Can; Song, Ying-Wei; Li, Lin-Feng; Xie, Ai-Jun

    2007-08-01

    Comparison research of different constructed wetland types to treat lake Wulihu water was carried out. Under the condition of the loading rates 0.8 m3/(m2 x d), the removal efficiencies of the vertical flow wetland (VFW), subsurface flow wetland (SFW) and free surface wetland(FSW) had the following results: To ammonia nitrogen (NH4(+)-N) the average removal rates were 33.2%, 27.4% and 14.1%, respectively; To total nitrogen (TN) the average removal rates were 52.3% , 50.1% and 19.2%, respectively; To total phosphorus (TP) the average removal rates were 58.8%, 57.9% and 26.3%, respectively; To permanganate index the average removal rates were 37.2%, 38.3% and 14.8%, respectively; To chlorophyll a (Chl-a) the average removal rates were 86.9%, 96.1% and 55.3%, respectively. Obviously, VFW and SFW are more effective than FSW at treating eutrophicated water such as Lake Wulihu which with characters of low organically pollution and with high nitrogen and phosphorus pollution, and the VFW is the most effective on the removal of NH4(+)-N, TN and TP. SFW is the most effective on the removal of permanganate index and Chl-a. The effluent stability of VFW is better than SFW, and the SFW is better than FSW.

  19. Influence of chlorothalonil on the removal of organic matter in horizontal subsurface flow constructed wetlands.

    PubMed

    Casas-Zapata, Juan C; Ríos, Karina; Florville-Alejandre, Tomás R; Morató, Jordi; Peñuela, Gustavo

    2013-01-01

    This study investigates the effects of chlorothalonil (CLT) on chemical oxygen demand (COD) and dissolved organic carbon (DOC) in pilot-scale horizontal subsurface flow constructed wetlands (HSSFCW) planted with Phragmites australis. Physicochemical parameters of influent and effluent water samples, microbial population counting methods and statistical analysis were used to evaluate the influence of CLT on organic matter removal efficiency. The experiments were conducted on four planted replicate wetlands (HSSFCW-Pa) and one unplanted control wetland (HSSFCW-NPa). The wetlands exhibited high average organic matter removal efficiencies (HSSFCW-Pa: 80.6% DOC, 98.0% COD; HSSFCW-NPa: 93.2% DOC, 98.4% COD). The addition of CLT did not influence organic removal parameters. In all cases CLT concentrations in the effluent occurred in concentrations lower than the detection limit of the analytical method. Microbial population counts from HSSFCW-Pa showed significant correlations among different microbial groups and with different physicochemical variables. The apparent independence of organic matter removal and CLT inputs, along with the CLT depletion observed in effluent samples demonstrated that HSSFCW are a viable technology for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT.

  20. An integrated model of substrate clogging in vertical flow constructed wetlands.

    PubMed

    Hua, G F; Li, L; Zhao, Y Q; Zhu, W; Shen, J Q

    2013-04-15

    This paper presents an integrated model of substrate clogging in a vertical flow constructed wetland (VFCW). The model simulates the reduction of pore space in the wetland substrate due to combined influences of various physical, biogeochemical and plant-related processes. A series of experiments based on laboratory-scale VFCWs were conducted to examine and measure key parameters related to clogging of the wetland substrate during operation under different conditions. The model was then validated using data collected from the experiments. The results showed that the model was able to replicate the clogging phenomenon as observed in the experiments, in particular, the characteristic clogging time. The model also predicted well individual contributions to clogging by accumulated inert suspended solids, microbial biomass and plant root materials during the wetland operation. Although the validation was based on the laboratory data, the results indicated that the model describes well the processes underlying the clogging and has the potential to become a tool for assessing the performance of prototype CWs in relation to clogging at both the design and operation stages. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Low methane flux from a constructed boreal wetland

    NASA Astrophysics Data System (ADS)

    Clark, M. G.; Humphreys, E.; Carey, S. K.

    2016-12-01

    The Sandhill Fen Watershed project in northern Alberta, Canada, is a pilot study in reconstructing a mixed upland and lowland boreal plain ecosystem. The physical construction of the 50 ha area was completed in 2012 and revegetation programs, through planting and seeding, began that same year and continued into 2013. Since then, the vegetation has developed a substantial cover over the reclaimed soil and peat substrates used to cap the engineered topography constructed from mine tailings. To monitor the dynamics of carbon cycling processes in this novel ecosystem, near weekly gas chamber measurements of methane fluxes were carried out over 3 growing seasons. Soil moisture, temperature and ion flux measurements, using Plant Root Simulator probes, were also collected alongside the gas flux plots. In the 3rd season, a transect was established in the lowlands along a moisture gradient to collect continuous reduction-oxidation potential measurements along with these other variables. Overall, methane effluxes remained low relative to what is expected for rewetted organic substrates. However, there is a trend over time towards increasing methane gas emissions that coincides with increasing fluxes of reduced metal ions and decreasing fluxes of sulphate in the fully saturated substrates. The suppressed levels of methane fluxes are possibly due to naturally occurring high levels of sulphate in the donor materials used to cap the ecosystem construction.

  2. Seeking a way to promote the use of constructed wetlands for domestic wastewater treatment in developing countries.

    PubMed

    Zurita, F; Belmont, M A; De Anda, J; White, J R

    2011-01-01

    The aim of this study was to evaluate the domestic wastewater treatment efficiency as well as the survivability of commercially valuable ornamental plants in subsurface flow wetlands (SSFW) for domestic wastewater (DWW) treatment in laboratory and pilot wetland studies. The laboratory scale study included five different species (Zantedeschia aethiopica, Strelitzia reginae, Anthurium andreanum, Canna hybrids and Hemmerocallis dumortieri) that were evaluated in horizontal flow subsurface treatment cells. All the plants survived during the 6-month experimental period demonstrating high wetland nutrient treatment efficiency. In order to validate and expand these preliminary results, a pilot-scale wetland study was carried out in SSFWs under two different flow regimes (horizontal and vertical flow). Four ornamental species were tested during a 1-year period: Zantedeschia aethiopica, Strelitzia reginae, Anthurium andreanum and Agapanthus africanus. The removal efficiencies were significantly higher in the vertical subsurface-flow constructed wetlands (VFCW) for all pollutants, except for nitrate (NO(3)-N), total nitrogen (TN) and total suspended solids (TSS). These results show that it is feasible to use select non-wetland plants with high market value in SSFWs without reducing the efficiency of the wastewater treatment system, although future work should continue in order to apply this technology in a large scale. The added value of floriculture in treatment wetlands can help to promote the use of constructed wetlands (CW) for domestic wastewater treatment in developing countries where economical resources are scarce and water pollution with DWW is common.

  3. Efficient removal of antibiotics in surface-flow constructed wetlands, with no observed impact on antibiotic resistance genes.

    PubMed

    Berglund, Björn; Khan, Ghazanfar Ali; Weisner, Stefan E B; Ehde, Per Magnus; Fick, Jerker; Lindgren, Per-Eric

    2014-04-01

    Recently, there have been growing concerns about pharmaceuticals including antibiotics as environmental contaminants. Antibiotics of concentrations commonly encountered in wastewater have been suggested to affect bacterial population dynamics and to promote dissemination of antibiotic resistance. Conventional wastewater treatment processes do not always adequately remove pharmaceuticals causing environmental dissemination of low levels of these compounds. Using constructed wetlands as an additional treatment step after sewage treatment plants have been proposed as a cheap alternative to increase reduction of wastewater contaminants, however this means that the natural microbial community of the wetlands becomes exposed to elevated levels of antibiotics. In this study, experimental surface-flow wetlands in Sweden were continuously exposed to antibiotics of concentrations commonly encountered in wastewater. The aim was to assess the antibiotic removal efficiency of constructed wetlands and to evaluate the impact of low levels of antibiotics on bacterial diversity, resistance development and expression in the wetland bacterial community. Antibiotic concentrations were measured using liquid chromatography-mass spectrometry and the effect on the bacterial diversity was assessed with 16S rRNA-based denaturing gradient gel electrophoresis. Real-time PCR was used to detect and quantify antibiotic resistance genes and integrons in the wetlands, during and after the exposure period. The results indicated that the antibiotic removal efficiency of constructed wetlands was comparable to conventional wastewater treatment schemes. Furthermore, short-term treatment of the constructed wetlands with environmentally relevant concentrations (i.e. 100-2000 ng×l(-1)) of antibiotics did not significantly affect resistance gene concentrations, suggesting that surface-flow constructed wetlands are well-suited for wastewater treatment purposes. Copyright © 2014 Elsevier B.V. All rights

  4. Potential internal loading of phosphorus in a wetland constructed in agricultural land.

    PubMed

    Pant, H K; Reddy, K R

    2003-03-01

    Wetland construction on agricultural or dairy lands could result in solubilization of phosphorus (P) stored in soils and release to the water column. To study the extent of P flux during the start-up period of a constructed wetland, intact soil-cores from areas used for dairy operations, in Okeechobee, Florida, USA were obtained and flooded with adjacent creek water. In the first 28-day hydraulic-retention period, P concentration in the water column increased several fold due to rapid P flux from impacted soils. A continuous decrease in P flux to the water column until the third hydraulic retention cycle (initial influent P concentration 0.2 mgL(-1)), and constant thereafter suggest that the effect of initial influent P upon long-term P flux from soils could be limited. The initial release maybe due to high concentration of labile P in impacted soils; however, slow dissolution of relatively stable P pools could maintain a steady flux, well above of that observed from non-impacted soils. Water soluble P along with double acid-extractable magnesium explained 76% of the variability in cumulative P flux to the water column. Apparently, co-occurrence of active adsorption-desorption phenomena due to independent maintenance of equilibrium by individual P compounds regulates P dynamics of the water column. The results indicated that equilibrium P concentration of the water column of the wetland would be above 1.3 mgL(-1), which is well above the targeted P level in the water column of the Lake Okeechobee, one of the main water bodies in the area (0.04 mg PL(-1)). This suggests construction of wetlands in agricultural lands could result to substantial internal P loading. However, preventative measures including chemical amendments, establishment of vegetative communities or flushing the initially released P may potentially stabilize the system, and maintain P removal efficiency.

  5. Application of the gas tracer method for measuring oxygen transfer rates in subsurface flow constructed wetlands.

    PubMed

    Tyroller, Lina; Rousseau, Diederik P L; Santa, Santa; García, Joan

    2010-07-01

    The oxygen transfer rate (OTR) has a significant impact on the design, optimal operation and modelling of constructed wetlands treating wastewater. Oxygen consumption is very fast in wetlands and the OTR cannot be determined using an oxygen mass balance. This problem is circumvented in this study by applying the gas tracer method. Experiments were conducted in an unplanted gravel bed (dimensions L x W x d 125 x 50 x 35 cm filled with a 30-cm layer of 10-11-mm gravel) and a planted horizontal subsurface flow constructed wetland (HSSFCW) (L x W x d 110 x 70 x 38 cm filled with a 30-cm layer of 3.5-mm gravel with Phragmites australis). Tap water saturated with propane as gas tracer (pure or commercial cooking gas, depending on the test) was used. The mass transfer ratio between oxygen and commercial propane gas was quite constant and averaged R = 1.03, which is slightly lower than the value of R = 1.39 that is usually reported for pure propane. The OTR ranged from 0.31 to 5.04 g O(2) m(-2) d(-1) in the unplanted gravel bed and from 0.3 to 3.2 g O(2) m(-2) d(-1) in the HSSFCW, depending on the hydraulic retention time (HRT). The results of this study suggest that the OTR in HSSFCW is very low for the oxygen demand of standard wastewater and the OTR calculations based on mass balances and theoretical stoichiometric considerations overestimate OTR values by a factor that ranges from 10 to 100. The gas tracer method is a promising tool for determining OTR in constructed wetlands, with commercial gas proving to be a viable low-cost alternative for determining OTR.

  6. Laboratory assessment of atrazine and fluometuron degradation in soils from a constructed wetland.

    PubMed

    Weaver, M A; Zablotowicz, R M; Locke, M A

    2004-11-01

    Constructed wetlands offer promise for removal of nonpoint source contaminants such as herbicides from agricultural runoff. Laboratory studies assessed the potential of soils to degrade and sorb atrazine and fluometuron within a recently constructed wetland. The surface 3 cm of soil was sampled from two cells of a Mississippi Delta constructed wetland; one shallow area disturbed only hydrologically, and the second excavated to provide greater water-holding capacity. The excavated area was more acidic on average (pH 4.85 versus 5.21), but otherwise the physical properties and general microbial enzyme activities in the two areas were similar. Soils were treated with 84 and 68 microg kg(-1) soil (14)C-ring labeled atrazine and fluometuron, respectively, and incubated under either saturated (88% moisture, w:w) or flooded (1cm standing water) conditions. Soils were sampled over 32 days and extracted for herbicide and metabolite analysis. Under saturated conditions, fluometuron metabolized to desmethylfluometuron (DMF) with a half-life equal 25-27 days. However, under flooded conditions, the half-life of fluometuron was more than 175 days. Atrazine dissipated rapidly in saturated and flooded soil with a half-life of approximately 23 days, but only 10% of atrazine was mineralized to CO(2). The overall atrazine and fluometuron dissipation rates were similar between the two cells, but each area had a different pattern of metabolite accumulation. The major route of atrazine dissipation was incorporation of atrazine residues into methanol-nonextractable (soil-bound) components, with minimal extractable metabolite accumulation. A mixed-mode extractant (potassium phosphate:acetonitrile) recovered greater amounts of (14)C-residues from atrazine-treated soils, suggesting that hydrolysis of atrazine to hydroxylated metabolites was a major component of the bound residues. These studies indicate the potential for herbicide dissipation in wetland soils and a differential effect of

  7. Effects of plant root on hydraulic performance of clogging process in subsurface flow constructed wetland

    NASA Astrophysics Data System (ADS)

    Hua, Guofen; Zhao, Zhongwei; Zeng, Yitao

    2013-04-01

    Subsurface flow constructed wetlands (SFCWs) have proven to be an efficient ecological technology for the treatment of various kinds of wastewaters. The clogging issue is the main operational problem, which limits its wide application. Clogging is a complicated process with physical (such as physical filtration), biogeochemical and plant-related processes. It was generally stated that suspended solids accumulation and biofilm play dominant roles response for clogging. However, the role of plants in SFCWs clogging remains unclear and debatable. In this paper, the performance of plants in the whole clogging process was addressed based on the lab-experiments between planted and unplanted system by measuring effective porosity, coefficient of permeability of the substrate within different operation periods. Furthermore, flow pattern and transport properties of the clogging process in the planted and unplanted wetland systems were evaluated by hydraulic performance (e.g. mean residence time, short-circuiting, volumetric efficiency, number of continuously stirred tank reactors, hydraulic efficiency factor, etc.) with salt tracer experiments. Plants played different roles in different clogging stage. In the earlier clogging stage, there were no obvious different effects on clogging process between planted and unplanted system. The effective porosity and coefficient of permeability slightly decreased within the planted system, which indicated that plant root restricted the flow of water when the pore spaces were lager. In the middle and later clogging stage, especially, in the later stage, the effective porosity and the coefficient of permeability increased considerably in the plant root zone. Furthermore, the longer retention times and higher hydraulic efficiency factors were gained in the planted system compared to that of unplanted, which implied that growing roots might open the new pore spaces in the substrate. The results are expected to be useful in the design of

  8. Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000-2013).

    PubMed

    Zhang, Dong-Qing; Jinadasa, K B S N; Gersberg, Richard M; Liu, Yu; Tan, Soon Keat; Ng, Wun Jern

    2015-04-01

    Constructed wetlands (CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural (environmental) systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice, applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand (BOD) and total suspended solid (TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid (TSS) (91.3%), chemical oxygen demand (COD) (84.3%), and nitrogen (i.e., 80.7% for ammonium (NH)4-N, 80.8% for nitrate (NO)3-N, and 75.4% for total nitrogen (TN)) as compared to other wetland systems. Vertical subsurface flow (VSSF) CWs removed TSS (84.9%), BOD (87.6%), and nitrogen (i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN) more efficiently than horizontal subsurface flow (HSSF) CWs, while HSSF CWs (69.8%) showed better total phosphorus (TP) removal compared to VSSF CWs (60.1%). Floating treatment wetlands (FTWs) showed comparable removal efficiencies for BOD (70.7%), NH4-N (63.6%), and TP (44.8%) to free water surface (FWS) CW systems.

  9. Life cycle assessment of vertical and horizontal flow constructed wetlands for wastewater treatment considering nitrogen and carbon greenhouse gas emissions.

    PubMed

    Fuchs, Valerie J; Mihelcic, James R; Gierke, John S

    2011-02-01

    Life cycle assessment (LCA) is used to compare the environmental impacts of vertical flow constructed wetlands (VFCW) and horizontal flow constructed wetlands (HFCW). The LCAs include greenhouse gas (N(2)O, CO(2) and CH(4)) emissions. Baseline constructed wetland designs are compared to different treatment performance scenarios and to conventional wastewater treatment at the materials acquisition, assembly and operation life stages. The LCAs suggest that constructed wetlands have less environmental impact, in terms of resource consumption and greenhouse gas emissions. The VFCW is a less impactful configuration for removing total nitrogen from domestic wastewater. Both wetland designs have negligible impacts on respiratory organics, radiation and ozone. Gaseous emissions, often not included in wastewater LCAs because of lack of data or lack of agreement on impacts, have the largest impact on climate change. Nitrous oxide accounts for the increase in impact on respiratory inorganic, and the combined acidification/eutrophication category. The LCAs were used to assess the importance of nitrogen removal and recycling, and the potential for optimizing nitrogen removal in constructed wetlands.

  10. Robust biological nitrogen removal by creating multiple tides in a single bed tidal flow constructed wetland.

    PubMed

    Hu, Yuansheng; Zhao, Yaqian; Rymszewicz, Anna

    2014-02-01

    Achieving effective total nitrogen (TN) removal is one of the major challenges faced by constructed wetlands (CWs). To address this issue, multiple "tides" were proposed in a single stage tidal flow constructed wetland (TFCW). With this adoption, exceptional TN removal (85% on average) was achieved under a high nitrogen loading rate (NLR) of around 28 g Nm(-2)day(-1), which makes the proposed system an adequate option to provide advanced wastewater treatment for peri-urban communities and rural area. It was revealed that the multiple "tides" not only promoted TN removal performance, but also brought more flexibility to TFCWs. Adsorption of NH4(+)-N onto the wetland medium (during contact period) and regeneration of the adsorption capacity via nitrification (during bed resting) were validated as the key processes for NH4(+)-N conversion in TFCWs. Moreover, simultaneous nitrification denitrification (SND) was found to be significant during the bed resting period. These findings will provide a new foundation for the design and modeling of nitrogen conversion and oxygen transfer in TFCWs. © 2013.

  11. Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands.

    PubMed

    Mackintosh, Teresa J; Davis, Jenny A; Thompson, Ross M

    2016-01-01

    The impact of stormwater on stream biota is well documented, but less is known about the impacts on ecosystem processes, such as the breakdown of organic matter. This study sought to establish whether the degree of urbanisation affected rates of leaf-litter breakdown within constructed wetlands. A litter bag method was used to ascertain rate of decomposition along a gradient of urbanisation (total imperviousness, TI), in constructed wetlands in western and south-eastern Melbourne. A significant positive relationship between TI and breakdown rate was found in the south-eastern wetlands. The significant reduction in rate of invertebrate-mediated breakdown with increasing concentration of certain metals was consistent with other studies. However, overall there was an increase in rate of breakdown. Studies have shown that the effects of heavy metals can be negated if nutrient levels are high. Our results suggest that other parameters besides exposure to contaminants are likely to affect leaf litter breakdown. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Prediction of water quality index in constructed wetlands using support vector machine.

    PubMed

    Mohammadpour, Reza; Shaharuddin, Syafiq; Chang, Chun Kiat; Zakaria, Nor Azazi; Ab Ghani, Aminuddin; Chan, Ngai Weng

    2015-04-01

    Poor water quality is a serious problem in the world which threatens human health, ecosystems, and plant/animal life. Prediction of surface water quality is a main concern in water resource and environmental systems. In this research, the support vector machine and two methods of artificial neural networks (ANNs), namely feed forward back propagation (FFBP) and radial basis function (RBF), were used to predict the water quality index (WQI) in a free constructed wetland. Seventeen points of the wetland were monitored twice a month over a period of 14 months, and an extensive dataset was collected for 11 water quality variables. A detailed comparison of the overall performance showed that prediction of the support vector machine (SVM) model with coefficient of correlation (R(2)) = 0.9984 and mean absolute error (MAE) = 0.0052 was either better or comparable with neural networks. This research highlights that the SVM and FFBP can be successfully employed for the prediction of water quality in a free surface constructed wetland environment. These methods simplify the calculation of the WQI and reduce substantial efforts and time by optimizing the computations.

  13. Phytoremediation of water contaminated with mercury using Typha domingensis in constructed wetland.

    PubMed

    Gomes, Marcos Vinícius Teles; de Souza, Roberto Rodrigues; Teles, Vinícius Silva; Araújo Mendes, Érica

    2014-05-01

    The presence of mercury in aquatic environments is a matter of concern by part of the scientific community and public health organizations worldwide due to its persistence and toxicity. The phytoremediation consists in a group of technologies based on the use of natural occurrence or genetically modified plants, in order to reduce, remove, break or immobilize pollutants and working as an alternative to replace conventional effluent treatment methods due to its sustainability - low cost of maintenance and energy. The current study provides information about a pilot scale experiment designed to evaluate the potential of the aquatic macrophyte Typha domingensis in a constructed wetland with subsurface flow for phytoremediation of water contaminated with mercury. The efficiency in the reduction of the heavy metal concentration in wetlands, and the relative metal sorption by the T. domingensis, varied according to the exposure time. The continued rate of the system was 7 times higher than the control line, demonstrating a better performance and reducing 99.6±0.4% of the mercury presents in the water contaminated. When compared to other species, the results showed that the T. domingensis demonstrated a higher mercury accumulation (273.3515±0.7234 mg kg(-1)) when the transfer coefficient was 7750.9864±569.5468 L kg(-1). The results in this present study shows the great potential of the aquatic macrophyte T. domingensis in constructed wetlands for phytoremediation of water contaminated with mercury. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Integrated constructed wetlands: water management as a land-use issue, implementing the 'Ecosystem Approach'.

    PubMed

    Harrington, R; Carroll, P; Cook, S; Harrington, C; Scholz, M; McInnes, R J

    2011-01-01

    Awareness of the need for social, economic and environmental coherence in the management of water is becoming evermore apparent. Water supply as well as treatment is becoming more costly; a challenge that is not only limited to developing countries. The use of wetlands, natural and constructed, is now more widely accepted as a means of tackling a range of problems in water management to deliver this coherence. The use of 16 Integrated Constructed Wetlands that mimic shallow, emergent-vegetated, palustrine wetlands in a 2,500 ha catchment in County Waterford, Southeast Ireland, has shown a number of distinct advantages in implementing the all encompassing 'Ecosystem Approach', addressing the key elements for sustainable water management in an intensively used agricultural area. The significant increase in water quality, biodiversity, social amenities and acceptance by the local rural community provided by this 'real' field-scale demonstration show the benefits that such a joined-up approach can have on catchment management in the widest sense.

  15. Spatial distribution of N-cycling microbial communities showed complex patterns in constructed wetland sediments.

    PubMed

    Correa-Galeote, David; Marco, Diana E; Tortosa, Germán; Bru, David; Philippot, Laurent; Bedmar, Eulogio J

    2013-02-01

    Constructed wetlands are used for biological treatment of wastewater from agricultural lands carrying pollutants such as nitrates. Nitrogen removal in wetlands occurs from direct assimilation by plants and through microbial nitrification and denitrification. We investigated the spatial distribution of N-cycling microbial communities and genes involved in nitrification and denitrification in constructed wetland sediments receiving irrigation water. We used quantitative real-time PCR (qPCR) to characterize microbial communities. Geostatistical variance analysis was used to relate them with vegetation cover and biogeochemical sediment properties. The spatial distribution of the N-cycling microbial communities of sediments was heterogeneous and complex. Total communities of bacteria and crenarchaea showed different spatial distributions. Analysis of autocorrelation patterns through semivariance indicated a tendency towards a patchy distribution over scales around 10 m for genes involved in the nitrification and denitrification processes. In contrast, biogeochemical sediment properties showed diverse spatial distributions. While almost no patchiness was found for pH and moisture, patchiness at scales between 8 and 10 m was detected for carbon, nitrate and ammonia. Denitrification variables showed spatial autocorrelation at scales comparable to genes. However, denitrifying enzyme activity and potential N(2)O production showed a common spatial pattern, different from that of the N(2)O/(N(2)O + N(2)).

  16. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity to Hyalella azteca.

    PubMed

    Lizotte, Richard E; Moore, Matthew T; Locke, Martin A; Kröger, Robert

    2011-02-01

    The toxicity of a nutrient-pesticide mixture in nonvegetated and vegetated sections of a constructed wetland (882 m² each) was assessed using Hyalella azteca 48-h aqueous whole-effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple superphosphate, diazinon, and permethrin simulating storm-event agricultural runoff. Aqueous samples were collected at inflow, middle, and outflow points within each section 5 h, 24 h, 72 h, 7 days, 14 days, and 21 days postamendment. Nutrients and pesticides were detected throughout both wetland sections with concentrations longitudinally decreasing more in vegetated than nonvegetated section within 24 h. Survival effluent dilution point estimates-NOECs, LOECs, and LC₅₀s-indicated greatest differences in toxicity between nonvegetated and vegetated sections at 5 h. Associations of nutrient and pesticide concentrations with NOECs indicated that earlier toxicity (5-72 h) was from permethrin and diazinon, whereas later toxicity (7-21 days) was primarily from diazinon. Nutrient-pesticide mixture concentration-response assessment using toxic unit models indicated that H. azteca toxicity was due primarily to the pesticides diazinon and permethrin. Results show that the effects of vegetation versus no vegetation on nutrient-pesticide mixture toxicity are not evident after 5 h and a 21-day retention time is necessary to improve H. azteca survival to ≥90% in constructed wetlands of this size.

  17. Diversity of ammonia oxidising bacteria in a vertical flow constructed wetland.

    PubMed

    Tietz, A; Hornek, R; Langergraber, G; Kreuzinger, N; Haberl, R

    2007-01-01

    Vertical flow constructed wetlands (VFCWs) with intermittent loading are very suitable for nitrification. Ammonia oxidising bacteria (AOB) are the limiting step of nitration. Therefore the AOB community of a full-scale VFCW, receiving municipal wastewater, was investigated within this study. The diversity of the functional gene encoding the alpha-subunit of the ammonia monooxygenase (amoA), present only in AOB, was assessed by denaturing gradient gel electrophoresis (DGGE). Only very few amoA sequence types dominated the wetland filter substrate; nevertheless a stable nitrification performance could be observed. During the cold season the nitrification was slightly reduced, but it has been shown that the same AOB could be identified. No spatial AOB pattern could be observed within the filter body of the VFCW. The most prominent bands were excised from DGGE gels and sequenced. Sequence analyses revealed two dominant AOB lineages: Nitrosomonas europaea/"Nitrosococcus mobilis" and Nitrosospira. Species of the Nitrosomonas lineage are commonly found in conventional wastewater treatment plants (WWTPs). In contrast, members of the Nitrosospira lineage are rarely present in WWTPs. Our observations indicate that the AOB community in this VFCW is similar to that found in horizontal flow constructed wetlands, but differs from common WWTPs regarding the presence of Nitrosospira.

  18. [Treatment of 1, 2-dichlorobenzene in wastewater by using horizontal subsurface flow constructed wetlands].

    PubMed

    Ding, Cheng; Yang, Tang-Yi; Yu, Qian; Li, Zhao-Xia; Yang, Chun-Sheng

    2011-09-01

    Pilot-scale horizontal subsurface flow constructed wetlands (SFCW) planted with Phragmites australis were constructed to treat in 1,2-dichlorobenzene (o-DCB) wastewater. Different soil substrates of loam (W-L), fine sand (W-F) and coarse sand (W-C) were used in the three SFCW and a loam wetland with no reeds W-Z was taken as control. Results showed that the optimal hydraulic retention time (HRT) and pollutants surface loading rate(ALR)were 5 d and 150 mg x (m2 x d)(-1). Removal efficiencies for o-DCB of W-L, W-F, W-C and W-Z were 81.2%, 71.1%, 72.4% and 65.2%, respectively. The performance of systems achieved in mid-August and declined from October, with order of W-L > W-C > W-Z > W-F. Spatial concentration dynamics of o-DCB and dissolved oxygen (DO) were also investigated in W-L and W-Z, which indicated that DO was an important role to removal of o-DCB. The residual quantity of o-DCB in wetland substrate decreased along the flow direction and increased with the depth of substrate layers, the mean residual in the root, stem and leaf of reeds were 30.28, 14.85 and 6.18 microg x g(-1).

  19. Impact of hydraulic and carbon loading rates of constructed wetlands on contaminants of emerging concern (CECs) removal.

    PubMed

    Sharif, Fariya; Westerhoff, Paul; Herckes, Pierre

    2014-02-01

    Constructed wetlands remove trace organic contaminants via synergistic processes involving plant biomass that include hydrolysis, volatilization, sorption, biodegradation, and photolysis. Wetland design conditions, such as hydraulic loading rates (HLRs) and carbon loading rates (CLRs), influence these processes. Contaminant of emerging concern (CEC) removal by wetland plants was investigated at varying HLRs and CLRs. Rate constants and parameters obtained from batch-scale studies were used in a mechanistic model to evaluate the effect of these two loading rates on CEC removal. CLR significantly influenced CEC removal when wetlands were operated at HLR >5 cm/d. High values of CLR increased removal of estradiol and carbamazepine but lowered that of testosterone and atrazine. Without increasing the cumulative HLR, operating two wetlands in series with varying CLRs could be a way to improve CEC removal.

  20. [Water treatment efficiency of constructed wetland plant-bed/ditch systems].

    PubMed

    Wang, Zhong-Qiong; Zhang, Rong-Bin; Chen, Qing-Hua; Wei, Hong-Bin; Wang, Wei-Dong

    2012-11-01

    Shijiuyang constructed wetland (SJY-CW) in Jiaxing City adopted plant-bed/ditch systems originated from the natural landscape as its major functioning unit. The constructed root channel technology (CRCT) is the core technique applied within the plant-bed/ditch systems. Monitoring results demonstrated that the wetland had the capability of improving water quality indexes by one rank grade according to the national environmental quality standards for surface water (GB 3838-2002). In order to optimize the water quality improvement function of plant-bed/ditch systems and CRCT, a pilot project in SJY-CW was constructed from May to October, 2010. The project contained 16 independent experimental cells. Orthogonal test design was applied to probe into the effects of constructed root channel layers, plant species combination, and reinforced physical substrates on promoting the water quality amelioration efficiency of the plant-bed/ditch systems. Comprehensively considering water treatment effects, construction difficulty, and construction and maintenance cost, the recommended optimal ways are as follows. Plant straws were preferably paved under subsurface zones by two layers with a gap of 20-30 cm. The preferable plant combination was reed (Phragmites australis) plus wild rice (Zizania caduciflora). Calcite might be applied as alternative reinforced media in some suitable sites of plant-bed/ditch systems. Water treatment effects were compared between pilot project and the whole wetland area of SJY-CW. The results showed that the reinforced pilot project exhibited higher treatment efficiency for nutrients than SJY-CW itself. The removal rates of total nitrogen, total phosphorus, and ammonia nitrogen were increased by about 20% - 40% in the pilot project. This suggested that SJY-CW could release its vast water treatment potential by means of increasing water flux through the subsurface root channel zones of plant beds. Therefore, some adjustment and control measures could be

  1. Bacterial transformation and biodegradation processes simulation in horizontal subsurface flow constructed wetlands using CWM1-RETRASO.

    PubMed

    Llorens, Esther; Saaltink, Maarten W; Poch, Manel; García, Joan

    2011-01-01

    The performance and reliability of the CWM1-RETRASO model for simulating processes in horizontal subsurface flow constructed wetlands (HSSF CWs) and the relative contribution of different microbial reactions to organic matter (COD) removal in a HSSF CW treating urban wastewater were evaluated. Various different approaches with diverse influent configurations were simulated. According to the simulations, anaerobic processes were more widespread in the simulated wetland and contributed to a higher COD removal rate [72-79%] than anoxic [0-1%] and aerobic reactions [20-27%] did. In all the cases tested, the reaction that most contributed to COD removal was methanogenesis [58-73%]. All results provided by the model were in consonance with literature and experimental field observations, suggesting a good performance and reliability of CWM1-RETRASO. According to the good simulation predictions, CWM1-RETRASO is the first mechanistic model able to successfully simulate the processes described by the CWM1 model in HSSF CWs.

  2. Greenhouse gas production and efficiency of planted and artificially aerated constructed wetlands.

    PubMed

    Maltais-Landry, Gabriel; Maranger, Roxane; Brisson, Jacques; Chazarenc, Florent

    2009-03-01

    Greenhouse gas (GHG) emissions by constructed wetlands (CWs) could mitigate the environmental benefits of nutrient removal in these man-made ecosystems. We studied the effect of 3 different macrophyte species and artificial aeration on the rates of nitrous oxide (N(2)O), carbon dioxide (CO(2)) and methane (CH(4)) production in CW mesocosms over three seasons. CW emitted 2-10 times more GHG than natural wetlands. Overall, CH(4) was the most important GHG emitted in unplanted treatments. Oxygen availability through artificial aeration reduced CH(4) fluxes. Plant presence also decreased CH(4) fluxes but favoured CO(2) production. Nitrous oxide had a minor contribution to global warming potential (GWP<15%). The introduction of oxygen through artificial aeration combined with plant presence, particularly Typha angustifolia, had the overall best performance among the treatments tested in this study, including lowest GWP, greatest nutrient removal, and best hydraulic properties.

  3. Influence of vegetation on the removal of heavy metals and nutrients in a constructed wetland.

    PubMed

    Maine, M A; Suñe, N; Hadad, H; Sánchez, G; Bonetto, C

    2009-01-01

    A free water surface wetland was built to treat wastewater containing metals (Cr, Ni, Zn) and nutrients from a tool factory in Argentina. Water, sediment and macrophytes were sampled in the inlet and outlet area of the constructed wetland during three years. Three successive phases of vegetation dominance were developed and three different patterns of contaminant retention were observed. During the Eichhornia crassipes dominance, contaminants were retained in the macrophyte biomass; during the E. crassipes+Typha domingensis stage, contaminants were retained in the sediment and in the T. domingensis dominance stage, contaminants were retained in sediment and in the macrophyte biomass. Removal efficiency was not significantly different among the three vegetation stages, except for NH(4)(+) and i-P(diss). Because of its highest tolerance, T. domingensis is the best choice to treat wastewater of high pH and conductivity with heavy metals, a common result from many industrial processes.

  4. A review of a recently emerged technology: Constructed wetland--Microbial fuel cells.

    PubMed

    Doherty, Liam; Zhao, Yaqian; Zhao, Xiaohong; Hu, Yuansheng; Hao, Xiaodi; Xu, Lei; Liu, Ranbin

    2015-11-15

    Constructed wetlands (CWs) and microbial fuel cells (MFCs) are compatible technologies since both are reliant on the actions of bacteria to remove contaminants from wastewater. MFCs require the anode to remain anaerobic with the cathode exposed to oxygen while these redox conditions can develop naturally in CWs. For this reason, research into combining the two technologies (termed as CW-MFC) has emerged in recent years with the aim of improving the wastewater treatment capacity of wetlands while simultaneously producing electrical power. Based on the published work (although limited), this review aims to provide a timely, current state-of-the-art in CW-MFC while exploring future challenges and research directions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Physiological parameters of plants as indicators of water quality in a constructed wetland.

    PubMed

    Shelef, Oren; Golan-Goldhirsh, Avi; Gendler, Tanya; Rachmilevitch, Shimon

    2011-08-01

    Increasing demand for water has stimulated efforts to treat wastewater for reuse in agriculture. Decentralized facilities for wastewater treatment became popular as a solution to remote and small communities. These systems mimic natural wetlands, cleaning wastewater as they flow through a complex of filter media, microbial fauna, and vegetation. The function of plants in constructed wetlands (CWs) has not been fully elucidated yet. In the research reported here, we provide evidence for a new use of plant physiological parameters in CWs as bioindicators of water quality along the system. We measured improved plant performance downstream of the CW by means of photochemical efficiency, CO(2) assimilation rate, and cell membrane stability. In addition, we found evidence for temporal improvement of plant performance, which was correlated to the establishment phase of plants in a newly operating CW. It is suggested that improved monitoring and management of CWs should take into planning consideration the promising potential of phyto-indicators.

  6. Evaluation of an integrated constructed wetland to manage pig manure under Mediterranean climate.

    PubMed

    Nehmtow, Julie; Rabier, Jacques; Giguel, Raphaël; Coulomb, Bruno; Farnet, Anne Marie; Perissol, Claude; Alary, Arnaud; Laffont-Schwob, Isabelle

    2016-08-01

    Pig manure is a complex mixture with excessive nutrients such as ammonium, microbial pathogens and may contain contaminants such as antibiotics. Conventional pig manure management practices caused water contamination. Sludge treatment wetland has been evaluated to determine its potential use under Mediterranean climate aiming at a parsimonious use of water and preventing water contamination, two major steps to preserve water resources in the Mediterranean Basin. Preliminary NH4-N degradation was tested using aeration process and/or addition of commercial bacterial products. Aeration alone appeared to be sufficient to ensure nitrogen transformation of the pig manure at lab small-scale (10 L) and medium-scale (300 L). Selected plant species e.g., Carex hispida for use in the integrated constructed wetland tolerated the nitrogen content after aeration enabling their use in a treatment vertical bed.

  7. Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading.

    PubMed

    Yu, Guangwei; Tan, Meijuan; Chong, Yunxiao; Long, Xinxian

    2015-01-01

    For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs), two horizontal subsurface flow(HSSF) CWs and two vertical subsurface flow(VSSF) CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P) were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.

  8. Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading

    PubMed Central

    Yu, Guangwei; Tan, Meijuan; Chong, Yunxiao; Long, Xinxian

    2015-01-01

    For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs), two horizontal subsurface flow(HSSF) CWs and two vertical subsurface flow(VSSF) CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P) were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation. PMID:26218872

  9. Application of a constructed wetland for industrial wastewater treatment: a pilot-scale study.

    PubMed

    Chen, T Y; Kao, C M; Yeh, T Y; Chien, H Y; Chao, A C

    2006-06-01

    The main objective of this study was to examine the efficacy and capacity of using constructed wetlands on industrial pollutant removal. Four parallel pilot-scale modified free water surface (FWS) constructed wetland systems [dimension for each system: 4-m (L)x1-m (W)x1-m (D)] were installed inside an industrial park for conducting the proposed treatability study. The averaged influent contains approximately 170 mg l(-1) chemical oxygen demand (COD), 80 mg l(-1) biochemical oxygen demand (BOD), 90 mg l(-1) suspend solid (SS), and 32 mg l(-1) NH(3)-N. In the plant-selection study, four different wetland plant species including floating plants [Pistia stratiotes L. (P. stratiotes) and Ipomoea aquatica (I. aquatica)] and emergent plants [Phragmites communis L. (P. communis) and Typha orientalis Presl. (T. orientalis)] were evaluated. Results show that only the emergent plant (P. communis) could survive and reproduce with a continuous feed of 0.4m(3)d(-1) of the raw wastewater. Thus, P. communis was used in the subsequent treatment study. Two different control parameters including hydraulic retention time (HRT) (3, 5, and 7d) and media [vesicles ceramic bioballs and small gravels, 1cm in diameter] were examined in the treatment study. Results indicate that the system with a 5-d HRT (feed rate of 0.4m(3)d(-1)) and vesicles ceramic bioballs as the media had the acceptable and optimal pollutant removal efficiency. If operated under conditions of the above parameters, the pilot-plant wetland system can achieve removal of 61% COD, 89% BOD, 81% SS, 35% TP, and 56% NH(3)-N. The treated wastewater meets the current industrial wastewater discharge standards in Taiwan.

  10. Microbiology of a wetland ecosystem constructed to remediate mine drainage from a heavy metal mine.

    PubMed

    Hallberg, Kevin B; Johnson, D Barrie

    2005-02-01

    A pilot passive treatment plant (PPTP) was constructed to evaluate the potential of a composite wetland system to remediate acidic, metal-rich water draining the former Wheal Jane tin, in Cornwall, England. The treatment plant consists of three separate and controllable composite systems, each of which comprises a series of aerobic wetlands for iron oxidation and precipitation, a compost bioreactor for removing chalcophilic metals and to generate alkalinity, and rock filter ponds for removing soluble manganese and organic carbon. To understand the roles of microorganisms in remediating acid mine drainage (AMD) in constructed wetland ecosystems, populations of different groups of cultivatable acidophilic microbes in the various components of the Wheal Jane PPTP were enumerated over a 30-month period. Initially, moderately acidophilic iron-oxidising bacteria (related to Halothiobacillus neapolitanus) were found to be the major cultivatable microorganisms present in the untreated AMD, though later heterotrophic acidophiles emerged as the dominant group, on a numerical basis. Culturable microbes in the surface waters and sediments of the aerobic wetlands were similarly dominated by heterotrophic acidophiles, though both moderately and extremely acidophilic iron-oxidising bacteria were also present in significant numbers. The dominant microbial isolate in waters draining the anaerobic compost bioreactors was an iron- and sulfur-oxidising moderate acidophile that was closely related to Thiomonas intermedia. The acidophiles enumerated at the Wheal Jane PPTP accounted for 1% to 25% of the total microbial population. Phylogenetic analysis of 14 isolates from various components of the Wheal Jane PPTP showed that, whilst many of these bacteria were commonly encountered acidophiles, some of these had not been previously encountered in AMD and AMD-impacted environments.

  11. Effect of phosphate, iron and sulfate reduction on arsenic dynamics and bioaccumulation in constructed wetlands

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Moon, H. S.; Myneni, S.; Jaffe, P. R.

    2016-12-01

    Constructed wetlands are economically viable and highly efficient in the treatment of high As waters discharged from smelting process in the mining industry. However, arsenic (As) dynamics and bioaccumulation in constructed wetlands coupled to nutrients loading and associated biogeochemical changes are confounding and not well understood. In this study, we investigated the effect of phosphate, iron and sulfate reduction on As dynamics in the wetland rhizosphere and its bioaccumulation in plants using greenhouse mesocosms. Results show that high Fe (50µM ferrihydrite/g soil) and SO42- (5mM) treatments are most favorable for As sequestration in soils in the presence of wetland plants (Scirpus actus), probably because the biodegradable plant exudates released into the rhizosphere facilitates the microbial reduction of Fe(III), SO42- and As(V) to sequester As by precipitation/coprecipitation. Whereas, from the transition of oxidizing to reducing conditions, the loading of high phosphate (100µM) enhances the As release into groundwater and its accumulation in the plants, due to the competitive sorption between phosphate and arsenate as well as the reductive dissolution of Fe and As. As retention in soils and accumulation in plants were mainly controlled by SO42- rather than Fe levels. Compared with low SO42- (0.1mM) treatment, high SO42- resulted in 2 times more As in soils, 30 times more As in roots, and 49% less As in leaves. The As levels in soils are negatively correlated with the As levels in plant roots. An As speciation analysis in pore water indicated that 19% more dissolved As was reduced under high SO42- than low SO42- levels, and 30% more As(III) was detected under high PO43- than low PO43- levels, which is consistent with the fact that more dissimilatory arsenate-respiring bacteria were found under high SO42- and high PO43- levels.

  12. Effects of inorganic nitrogen enrichment on mosquitoes (Diptera: Culicidae) and the associated aquatic community in constructed treatment wetlands.

    PubMed

    Sanford, Michelle R; Chan, Karrie; Walton, William E

    2005-09-01

    Ammonium nitrogen (NH4-N) is a significant component of municipal and agricultural wastewaters, and nitrogen reduction is an important use of constructed treatment wetlands. The effects of ammonium nitrogen enrichment on resources of larval mosquitoes, larval mosquito abundance, adult mosquito production, and the abundance of related wetland organisms were examined in 0.1-ha replicate treatment wetlands. The hypothesis of a bottom-up effect induced by ammonium addition was not supported by bacterial abundance, mean bacterial cell size, or algal biomass in the water column. There was, however, a significant negative correlation between bacterial cell length and Culex tarsalis Coquillett (Diptera: Culicidae) larval abundance 1 wk later in wetlands enriched with ammonium nitrogen. Larval mosquito (Culex spp.) abundance in southern California wetlands enriched with NH4-N (mean approximately equal to 3 mg/liter) was significantly greater than in control wetlands at ambient nitrogen levels (8.3 mg NO3-N/liter, 0.1 mg NH4-N/liter). Adult mosquito production was nine-fold greater and chironomid larvae were significantly more abundant in wetlands enriched with NH4-N than in controls but other censused taxa exhibited no significant trends. Mosquitofish, Gambusia affinis (Baird & Girard), abundance was significantly reduced in enriched wetlands, but other potential mosquito predators were not significantly affected by ammonium enrichment.

  13. Loss of plant biodiversity over a seven-year period in two constructed wetlands in Central New York.

    PubMed

    Kearney, Miranda A; Fickbohm, Scott; Zhu, Weixing

    2013-05-01

    Since wetland construction projects are becoming more commonplace, meaningful follow-up studies are needed to evaluate how these systems change over time. To that end, the objective of our study was to examine the temporal changes in plant community composition and water chemistry in two constructed wetlands. We investigated two wetland sites that were constructed in 2003 in northern Otsego County, NY, a county that is largely dominated by agriculture. Site 1 was previously an active cow pasture and site 2 was previously a wet meadow surrounded by agricultural fields. No active plant introduction was made during the construction; however, both sites were located in areas with many remnant wetlands and were connected to through-flowing streams. In 2004 (Year 1) and 2010 (Year 7), the plant community composition and nitrogen retention were assessed. We found that both sites experienced site-wide declines in plant species richness, including the loss of upland and facultative upland species and the unanticipated loss of facultative wetland and some obligate species. We propose that high water levels, which, at their maximum depth were >1.5 m deeper than in Year 1, maintained by landowners in the years after the initial survey, may have been responsible for the unexpected loss of wetland species. We also found that site 1 exhibited considerable nitrogen retention in both Year 1 and Year 7; however, N concentrations were low at site 2 in both years.

  14. Colonization of a newly constructed urban wetland by mosquitoes in England: implications for nuisance and vector species.

    PubMed

    Medlock, Jolyon M; Vaux, Alexander G C

    2014-12-01

    Urban wetlands are being created in the UK as part of sustainable urban drainage strategies, to create wetland habitats lost during development, to provide a habitat for protected species, and to increase the public's access to 'blue-space' for the improvement of health and well-being. Sewage treatment reedbeds are also being incorporated into newly constructed wetlands to offer an alternative approach to dealing with sewage. This field study aims to provide the first UK evidence of how such newly constructed aquatic habitats are colonized by mosquitoes. A number of new aquatic habitats were surveyed for immature mosquitoes every fortnight over the first two years following wetland construction. The majority of mosquitoes collected were Culex sp. and were significantly associated with the sewage treatment reedbed system, particularly following storm events and sewage inflow. Other more natural aquatic habitats that were subject to cycles of drying and re-wetting contributed the majority of the remaining mosquitoes colonizing. Colonization of permanent habitats was slow, particularly where fluctuations in water levels inhibited emergent vegetation growth. It is recommended that during the planning process for newly constructed wetlands consideration is given on a case-by-case basis to the impact of mosquitoes, either as a cause of nuisance or as potential vectors. Although ornithophagic Culex dominated in this wetland, their potential role as enzootic West Nile virus vectors should not be overlooked.

  15. Loss of Plant Biodiversity Over a Seven-Year Period in Two Constructed Wetlands in Central New York

    NASA Astrophysics Data System (ADS)

    Kearney, Miranda A.; Fickbohm, Scott; Zhu, Weixing

    2013-05-01

    Since wetland construction projects are becoming more commonplace, meaningful follow-up studies are needed to evaluate how these systems change over time. To that end, the objective of our study was to examine the temporal changes in plant community composition and water chemistry in two constructed wetlands. We investigated two wetland sites that were constructed in 2003 in northern Otsego County, NY, a county that is largely dominated by agriculture. Site 1 was previously an active cow pasture and site 2 was previously a wet meadow surrounded by agricultural fields. No active plant introduction was made during the construction; however, both sites were located in areas with many remnant wetlands and were connected to through-flowing streams. In 2004 (Year 1) and 2010 (Year 7), the plant community composition and nitrogen retention were assessed. We found that both sites experienced site-wide declines in plant species richness, including the loss of upland and facultative upland species and the unanticipated loss of facultative wetland and some obligate species. We propose that high water levels, which, at their maximum depth were >1.5 m deeper than in Year 1, maintained by landowners in the years after the initial survey, may have been responsible for the unexpected loss of wetland species. We also found that site 1 exhibited considerable nitrogen retention in both Year 1 and Year 7; however, N concentrations were low at site 2 in both years.

  16. Influence of earthworm Eisenia fetida on Iris pseudacorus's photosynthetic characteristics, evapotranspiration losses and purifying capacity in constructed wetland systems.

    PubMed

    Xu, Defu; Li, Yingxue; Fan, Xiaolong; Guan, Yidong; Fang, Hua; Zhao, Xiaoli

    2013-01-01

    Four constructed wetland systems were studied to investigate the effects of adding Eisenia fetida on the purifying capacity of constructed wetlands. Addition of E. fetida increased the photosynthetic rate (Pn), transpiration rate (Tr) and chlorophyll meter value of leaves of Iris pseudacorus L. in the constructed wetlands by 16, 35 and 7%, respectively. Compared with the substrate only system, evapotranspiration losses were increased by 8, 48 and 56% for the wetland systems with substrate and E. fetida, with substrate and I. pseudacorus, and with substrate, I. pseudacorus and E. fetida, respectively. Addition of E. fetida to the substrate only and substrate and plant wetland systems decreased the substrate bulk density by 3 and 6%, respectively. The addition of E. fetida to the system with substrate and plants increased the removal efficiency of chemical oxygen demand (CODMn), total nitrogen (TN) and total phosphorus by 5, 7 and 22%, respectively. Evapotranspiration losses were significantly positively correlated with the removal efficiency of CODMn (P < 0.01). The significantly negative correlation between the removal efficiency TN and bulk density was found (P < 0.05). Therefore, E. fetida could stimulate I. pseudacorus growth and improve the substrate bulk density in the constructed wetland, resulting in enhanced purifying capacity.

  17. Correlation Among Soil Enzyme Activities, Root Enzyme Activities, and Contaminant Removal in Two-Stage In Situ Constructed Wetlands Purifying Domestic Wastewater.

    PubMed

    Ni, Lixiao; Xu, Jiajun; Chu, Xianglin; Li, Shiyin; Wang, Peifang; Li, Yiping; Li, Yong; Zhu, Liang; Wang, Chao

    2016-07-01

    Two-stage in situ wetlands (two vertical flow constructed wetlands in parallel and a horizontal flow constructed wetland) were constructed for studying domestic wastewater purification and the correlations between contaminant removal and plant and soil enzyme activities. Results indicated the removal efficiency of NH4 (+) and NO3 (-) were significantly correlated with both urease and protease activity, and the removal of total phosphorus was significantly correlated with phosphatase activity. Chemical oxygen demand removal was not correlated with enzyme activity in constructed wetlands. Plant root enzyme (urease, phosphatase, protease and cellulose) activity correlation was apparent with all contaminant removal in the two vertical flow constructed wetlands. However, the correlation between the plant root enzyme activity and contaminant removal was poor in horizontal flow constructed wetlands. Results indicated that plant roots clearly played a role in the removal of contaminants.

  18. Constructing wetlands: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NASA Astrophysics Data System (ADS)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-04-01

    Interest is growing in using soft sediment as a building material in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here the option of dredging some of the clay-rich lake-bed sediment and using it to construct 10.000 ha of wetland will soon go under construction. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a six-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling as well as yellowing of foliage. The N:P ratios of plant tissue were low and were affected not by hampered uptake of N but by enhanced uptake of P. Plant analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose that when building wetlands from these mud deposits Fe-tolerant species are used rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the building material and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  19. A Constructed Freshwater Wetland Shows Signs of Declining Net Ecosystem Exchange

    NASA Astrophysics Data System (ADS)

    Anderson, F. E.; Bergamaschi, B. A.; Windham-Myers, L.; Byrd, K. B.; Drexler, J. Z.; Fujii, R.

    2014-12-01

    The USGS constructed a freshwater-wetland complex on Twitchell Island in the Sacramento-San Joaquin Delta (Delta), California, USA, in 1997 and maintained it until 2012 to investigate strategies for biomass accretion and reduction of oxidative soil loss. We studied an area of the wetland complex covered mainly by dense patches of hardstem bulrush (Schoenoplectus acutus) and cattails (Typha spp.), with smaller areas of floating and submerged vegetation, that was maintained at an average depth of 55 cm. Using eddy covariance measurements of carbon and energy fluxes, we found that the combination of water management and the region's Mediterranean climate created conditions where peak growing season daily means of net ecosystem exchange (NEE) reached -45 gCO2 m-2 d-1 and averaged around -30 gCO2 m-2 d-1 between 2002 through 2004. However, when measurements resumed in 2010, NEE rates were a fraction of the rates previously measured, approximately -6 gCO2 m-2 d-1. Interestingly, NEE rates in 2011 doubled compared to 2010 (-13 gCO2 m-2 d-1). Methane fluxes, collected in 2010 to assess a complete atmospheric carbon budget, were positive throughout the year, with daily mean flux values ranging from 50 to 300 mg CH4 m-2 d-1. As a result, methane flux reduced NEE values by approximately one-third, and when the global warming potential was considered, the wetland became a net global warming potential source. We found that carbon cycling in a constructed wetland is complex and can change over annual and decadal timescales. We investigated possible reasons for differences between flux measurements from 2002 to 2004 and those from 2010 and 2011: (1) changes in methodology, (2) differences in weather conditions, (3) differences in gross primary productivity relative to respiration rates, and (4) the amount of living plant tissue relative to brown accumulations of senesced plant litter. We hypothesize that large mats of senesced material within the flux footprint could have

  20. Phytoremediation of Water Using Phragmites karka and Veteveria nigritana in Constructed Wetland.

    PubMed

    Badejo, Adedayo A; Sridhar, Mynepalli K C; Coker, Adewale O; Ndambuki, Julius M; Kupolati, Williams K

    2015-01-01

    Constructed wetland is an innovative and emerging ecological technology for wastewater treatment. This study was conducted to investigate the effectiveness of a Vegetated Submerged Bed Constructed Wetland (VSBCW) for removal of heavy metals from industrial wastewater in a steel manufacturing company. A pilot Effluent Treatment Plant (ETP) consisting of equalization basin, two VSBCW basins and a storage tank was constructed. The VSBCW was constructed using 10-30 mm round granite for the different zones. This was overlaid by 200 mm deep granite and 150 mm washed sand with Phragmites karka, Vetiveria nigritana and Cana lilies as macrophytes. Irrigation of macrophytes using effluent from the industry was done after 3 months of planting and ETP monitored. Industrial wastewater samples were collected and analyzed for heavy metals such as zinc (Zn), lead (Pb), iron (Fe), manganese (Mn), magnesium (Mg) and chromium (Cr) to know the treatment efficiency of the ETP. Results indicated that the removal efficiencies of the VSBCW for Pb, Mg and Cr were 15.4%, 79.7% and 97.9% respectively. Fe and Mn were seen to increase by 1.8% and 33% respectively. The ETP using locally available macrophytes is effective in the phytoremediation of heavy metals, particularly Cr from the wastewater.

  1. Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures.

    PubMed

    Tanner, C C; Nguyen, M L; Sukias, J P S

    2005-01-01

    Nitrogen removal performance is reported for constructed wetlands treating subsurface drainage from irrigated and rain-fed dairy pastures in North Island, New Zealand. Flow-proportional sampling of inflow and outflow concentrations were combined with continuous flow records to calculate mass balances for the wetlands. Drainage flows from the irrigated catchment were 2.5-4 fold higher and N exports up to 5 fold higher per unit area than for the rain-fed catchment. Hydraulic and associated N loadings to the wetlands were highly pulsed, associated with rainfall, soil water status, and irrigation events. Transient pulses of organic nitrogen were an important form of N loss from the rain-fed landscape in the first year, and were very effectively removed in the wetland (> 90%). Median nitrate concentrations of approximately 10 g m(-3) in the drainage inflows were reduced by 15-67% during passage through the wetlands and annual nitrate-N loads by 16-61% (38-31 7 g N m(-2)y(-1)). Generation in the wetlands of net ammoniacal-N and organic-N (irrigated site) partially negated reduction in nitrate-N loads. The results show that constructed wetlands comprising 1-2% of catchment area can provide moderate reductions in TN export via pastoral drainage, but performance is markedly influenced by variations in seasonal loading and establishment/maturation factors.

  2. Comparison of microfauna communities in full scale subsurface flow constructed wetlands used as secondary and tertiary treatment.

    PubMed

    Puigagut, Jaume; Salvadó, Humbert; García, David; Granes, Francesc; García, Joan

    2007-04-01

    In order to evaluate the microfauna composition and distribution in two horizontal subsurface flow constructed wetlands used as secondary and tertiary treatment a full-scale wastewater treatment plant was monitored during five months. Results indicate that total microfauna abundance in the wetland treating primary influents is around five times higher than that found in the wetland treating secondary influents. Ciliated protozoa and microflagellates are the most important microfauna groups in both wetlands; microflagellates in terms of abundance and ciliates in terms of biomass. The most abundant ciliate species in the wetland treating primary influents are polysaprobic organisms as Dexiostoma campylum, Trimyema compressum, and to a lesser extend Metopus spp. On the other hand, the most important ciliate species found in the wetland treating secondary influents are mainly aerobic ciliates as Vorticella comvallaria-complex, Aspidisca cicada, Litonotus lamella and some ciliates belonging to the group of the scuticociliates and Hypotrichidae. The sort of the organic matter treated (particulated or dissolved) is at least as important as the amount of it in order to explain microfauna dynamics in constructed wetlands.

  3. Performance comparison of constructed wetlands with gravel- and rice husk-based media for phenol and nitrogen removal.

    PubMed

    Tee, H C; Seng, C E; Noor, A Md; Lim, P E

    2009-05-15

    This study aims to compare the performance of planted and unplanted constructed wetlands with gravel- and raw rice husk-based media for phenol and nitrogen removal. Four laboratory-scale horizontal subsurface-flow constructed wetland units, two of which planted with cattail (Typha latifolia) were operated outdoors. The units were operated at a nominal hydraulic retention time of 7 days and fed with domestic wastewater spiked with phenol concentration at 300 mg/L for 74 days and then at 500 mg/L for 198 days. The results show that planted wetland units performed better than the unplanted ones in the removal and mineralization of phenol. This was explained by the creation of more micro-aerobic zones in the root zone of the wetland plants which allow a faster rate of phenol biodegradation, and the phenol uptake by plants. The better performance of the rice husk-based planted wetland compared to that of the gravel-based planted wetland in phenol removal could be explained by the observation that more rhizomes were established in the rice husk-based wetland unit thus creating more micro-aerobic zones for phenol degradation. The role of rice husk as an adsorbent in phenol removal was considered not of importance.

  4. Evaluation of the biotic potential of microorganisms and higher plants to enhance the quality of constructed wetlands. Final report

    SciTech Connect

    Mays, D.A.; Floyd, M.; Taylor, R.W.; Sistani, K.

    1998-09-30

    A project was carried out from October 1, 1991 through September 30, 1998 to evaluate the growth of several species of wetland plants in constructed cells using mine spoil as a growth medium, to evaluate microbial diversity and finally, to demonstrate the concept on an actual strip-mined site. In order to gain background information for evaluation of constructed wetlands, several wetlands on both undisturbed and strip-mined areas were evaluated to determine the physical and chemical characteristics of the substrates as well as the vegetation characteristics. The research phase of this projects consisted of 10 wetland cells each 7x16 m in size with the water depth varying from 0 to 40 cm. The substrates were allowed to stabilize over winter and each cell was planted in the spring of 1993 with 18 plants each of cattail, maidencance, soft stem bulrush and pickerel weed. All cells were thickly vegetated by the end of the first growing season.

  5. Design and performance of a pilot-scale constructed wetland treatment system for natural gas storage produced water.

    PubMed

    Kanagy, Laura E; Johnson, Brenda M; Castle, James W; Rodgers, John H

    2008-04-01

    To test the hypothesis that water produced from natural gas storage wells could be treated effectively by constructed wetland treatment systems, a modular pilot-scale system was designed, built, and used for treating gas storage produced waters. Four simulated waters representing the range of contaminant concentrations typical of actual produced waters were treated, and the system's performance was monitored. Freshwater wetland cells planted with Schoenoplectus californicus and Typha latifolia were used to treat fresh and brackish waters. Saline and hypersaline waters were treated by saltwater wetland cells planted with Spartina alterniflora and by reverse osmosis. Effective removal of cadmium, copper, lead, and zinc was achieved by the pilot-scale system. Results suggest that use of specifically designed constructed wetland treatment systems provides a flexible and effective approach for treating gas storage produced waters over a wide range of compositions.

  6. Performance of a constructed wetland in treating brackish wastewater from commercial recirculating and super-intensive shrimp growout systems.

    PubMed

    Shi, Yonghai; Zhang, Genyu; Liu, Jianzhong; Zhu, Yazhu; Xu, Jiabo

    2011-10-01

    A recirculating aquaculture system was developed for treating Pacific white shrimp (Litopenaeus vannamei) production wastewater using an integrated vertical-flow (IVF) and five connected integrated horizontal flow (IHF) constructed wetlands as water treatment filters for mesohaline conditions (8.25‰-8.26‰ salinity). The constructed wetlands demonstrated the ability to reduce total nitrogen, total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphorous, chemical oxygen demand, and total suspended solids to levels significantly lower than those in effluents from culture tanks. Various water quality parameters in the culture tanks were deemed suitable for shrimp culture. The actual ratio of wetland area (A(w)) to culture tank area (A(t)) was 1.1439, and the estimated optimal ratio A(w)/A(t) was approximately 1. The IVF-IHF wetlands showed flexibility and reliability in consistently removing the main pollutants from commercial recirculating and super-intensive shrimp growout systems throughout the culture period.

  7. [Effects of enhanced dephosphorization in the constructed wetland using water-granulated slag as matrix].

    PubMed

    Li, Hai-bo; Yang, Rui-song; Li, Xiao-dong; Sun, Tie-heng

    2009-08-15

    The phosphorus adsorption and desorption effects of water-granulated slag (WGS) were studied. A simulated vertical flow constructed wetland system was constituted using WGS as the main matrix. The influences of hydraulic residence time (HRT) and pollution load on phosphorus removal were investigated. The contributions of phosphorus removal of different horizon layers in up-flow and down-flow matrixes were studied. The results showed that WGS was a kind of adaptive desorption material for wetland due to its high saturated phosphorus adsorptive capacity (3333 mg x kg(-1)). The content of soluble calcium of WGS is 0.084%, which provides a suitable pH (7.54) for microbes and plants growth in wetland. The HRT is in positive correlation with phosphorus removal rate. The phosphorus removal rates decrease 5.9%-4.7% and 2.4%-4.7% when HRT decreases from 1 d to 0.5 d and form 2 d to 1 d, respectively. The phosphorus removal rates exceed 85% at 1 d HRT in WGS wetland. That means the optimized HRT is 1 d, and extending HRT infinitely is not helpful to phosphorus removal. The pollution load is in negative correlation with phosphorus removal rate under the conditions of steady influx concentration. The phosphorus removal rates maintain 85% when the pollution load is from 12.2 g x (m2 x d)(-1) to 36.8 g x (m2 x d)(-1). When the pollution load increases to 48.9 g x (m2 x d)(-1), the phosphorus removal rate decreases to 65% . The phosphorus removal rate exceeds 82% when the pollution load is less than 36.8 g x (m2 x d)(-1). That means higher pollution load will cause the calcium and aluminum active points of phosphorus adsorption shielded, which exist both on matrix surface and in inner pores. The range of optimized pollution load is from 24.5 g x (m2 x d)(-1) to 36.8 g x (m2 x d)(-1). The graduation mode of WGS in top layer and conventional materials in lower layer is helpful to phosphorus removal in vertical flow wetland. The phosphorus adsorptive capacities in up-flow and down

  8. Limestone and Zeolite as Alternative Media in Horizontal Subsurface Flow Constructed Wetlands: Laboratory-Scale Studies

    NASA Astrophysics Data System (ADS)

    Lizama, K.; Jaque, I.; Ayala, J.

    2016-12-01

    Arsenic is well known for its chronic toxicity. Millions of people around the world are currently at risk, drinking water with As concentrations above 10 ppb, the WHO drinking water guideline. Although different treatment options exist, they are often limited by elevated costs and maintenance requirements. Constructed wetlands are a natural water treatment system, capable to remove metals and metalloids -including As- via different physical, chemical and biological processes. The use of alternative supporting media to enhance As removal in subsurface flow wetlands has been recommended, but not sufficiently studied. Limestone and zeolite have been identified as effective supporting media in subsurface flow wetlands aiming As removal. However, there are still key aspects to be addressed, such as the implications of using these media, the speciation in the solid phase, the role of vegetation, etc. This study investigated the performance of limestone and zeolite in three types of experiments: batch, column and as main supporting media in a bench scale horizontal subsurface flow wetland system. Synthetic water resembling a contaminated river in Chile (As concentration=3 mg/L, Fe concentration= 100 mg/L, pH=2) was used in all experiments. In the batch experiments, the As concentration, the mass of media and the contact time were varied. The column system consisted of three limestone columns and three zeolite columns, operated under a hydraulic loading of 20 mm/d. The wetland system consisted of twelve PVC cells: six filled with zeolite and six with limestone. Phragmites australis were planted in three cells of each media type, as control cells. From the batch experiments, maximum As sorption capacities as indicated by Langmuir model were 1.3 mg/g for limestone and 0.17 mg/g for zeolite, at 18 h contact time and 6.3 g/L medium concentration. EDS and XPS analyses revealed that As and Fe were retained in zeolite at the end of the batch experiments. Zeolite and limestone

  9. Mechanical resistance properties of gravel used in subsurface flow constructed wetlands: implications for clogging.

    PubMed

    Pedescoll, Anna; Passos, Fabiana; Alba, Elisenda; García, Joan; Puigagut, Jaume

    2011-01-01

    Gravel constitutes the filter medium in subsurface flow constructed wetlands (SSF CWs) and its porosity and hydraulic conductivity decrease over time (clogging), limiting the lifespan of the systems. Using gravel of poor quality accelerates clogging in wetlands. In this study, gravel samples from six different wetland systems were compared with regards to their mineral composition and mechanical resistance properties. Results showed that both mineralogy and texture are related to mechanical resistance. Accordingly, gravel with high content of quartz (> 80%) showed a lower percentage of broken particles (0.18-1.03%) than those with lower content of quartz (2.42-4.56% media broken). Although granite is formed by high durability minerals, its non-uniform texture results in a lower resistance to abrasion (ca. 10% less resistance than calcareous gravel). Therefore, it is recommended to use gravels composed mainly of quartz or, when it is not available, limestone gravels (rounded and uniform) are recommended instead. The resistance to abrasion (LAA test) seems to be a good indicator to determine the mechanical properties of gravels used in CWs. It is recommended to use gravels with LAA below 30% in order to avoid a rapid clogging due to gravel crumbling and subsequent mineral solids accumulation.

  10. Winery wastewater treatment by constructed wetlands and the use of treated wastewater for cash crop production.

    PubMed

    Mulidzi, A R

    2007-01-01

    A 45 m long, 4 m wide and 1 m deep wetland was constructed at Goudini in 2002 to treat distillery and winery effluent. After the plants were fully established, the wastewater with an average chemical oxygen demand (COD) of 14,000 mg/l was introduced to the wetland system at a rate of 4,050 litres per day. After treatment, wastewater at the outlet had an average COD of 500 mg/l, indicating more than 90% COD removal. After treatment, the wastewater was used to irrigate cash crops as part of poverty alleviation for farm workers. The experiment consisted of four treatment: clean irrigation water with fertilizer applied (B1); clean irrigation water without fertilizer applied (B2); wastewater irrigation with fertilizer applied (B3); and wastewater irrigation without fertilizer applied (B4). These were replicated seven times. Cabbage was cultivated as a cash crop. The results indicated that cabbage could be irrigated with winery wastewater treated by wetlands. The study found that there was significant difference between treatments that were fertilized compared with those that were not fertilized. The results indicated that wastewater irrigation improved the nutritional status of the soil.

  11. Performance of pilot-scale constructed wetlands for secondary treatment of chromium-bearing tannery wastewaters.

    PubMed

    Dotro, Gabriela; Castro, Silvana; Tujchneider, Ofelia; Piovano, Nancy; Paris, Marta; Faggi, Ana; Palazolo, Paul; Larsen, Daniel; Fitch, Mark

    2012-11-15

    Tannery operations consist of converting raw animal skins into leather through a series of complex water- and chemically-intensive batch processes. Even when conventional primary treatment is supplemented with chemicals, the wastewater requires some form of biological treatment to enable the safe disposal to the natural environment. Thus, there is a need for the adoption of low cost, reliable, and easy-to-operate alternative secondary treatment processes. This paper reports the findings of two pilot-scale wetlands for the secondary treatment of primary effluents from a full tannery operation in terms of resilience (i.e., ability to produce consistent effluent quality in spite of variable influent loads) and reliability (i.e., ability to cope with sporadic shock loads) when treating this hazardous effluent. Areal mass removal rates of 77.1 g COD/m2/d, 11 g TSS/m2/d, and 53 mg Cr/m2/d were achieved with a simple gravity-flow horizontal subsurface flow unit operating at hydraulic loading rates of as much as 10 cm/d. Based on the findings, a full-scale wetland was sized to treat all the effluent from the tannery requiring 68% more land than would have been assumed based on literature values. Constructed wetlands can offer treatment plant resilience for minimum operational input and reliable effluent quality when biologically treating primary effluents from tannery operations.

  12. Removal of total suspended solids from wastewater in constructed horizontal flow subsurface wetlands.

    PubMed

    Manios, T; Stentiford, E I; Millner, P

    2003-06-01

    Subsurface horizontal flow experimental wetlands (reed beds), were designed and built based on a combination of two design methodologies, that of the WRc and Severn Trent Water plc (1996) and that of the USA, EPA (1988). Four different growing media were used with a combination of top soil, gravel, river sand, and mature sewage sludge compost, to determine the best substrate for total suspended solids (TSS) removal. Eight units were constructed, two for each growing media. One bed for each pair was planted with Typha latifolia plants commonly known as cattails. Primary treated domestic wastewater, was continuously fed to the beds for more than six months. All eight beds performed very well. The best performance was achieved by the gravel reed beds with an almost constant removal rate above 95% and an average effluent concentration of less than 10 mg/L. Soil based beds containing top soil and sand, managed to reach values of removal around 90%. The wetlands containing compost in their substrate, produced an effluent with average concentration of less than 30 mg/L and a percentage removal between 80% and 90%. As expected, there was no significant difference in the performance of planted and unplanted wetlands.

  13. Clogging of vertical-flow constructed wetlands treating urban wastewater contaminated with a diesel spill.

    PubMed

    Al-Isawi, Rawaa; Scholz, Miklas; Wang, Yu; Sani, Abdulkadir

    2015-09-01

    Clogging often leads to a decrease of the treatment performance of wetlands. The aims of this study were to compare the impact of different design and operational variables on the treatment efficiency and clogging processes and to model suspended solid (SS) accumulation within the saturated wetland zone using the Wang-Scholz model. Different vertical-flow constructed wetlands were operated from June 2011 until April 2014. Four treatment periods were assessed: set-up, first year after set-up period, second year after set-up period and diesel spill (for selected filters only). The filter with the highest chemical oxygen demand (COD) loading but no diesel contamination performed the best in terms of COD and biochemical oxygen demand (BOD) removal for the fourth and final treatment period. Filters contaminated by diesel performed worse in terms of COD and BOD but considerably better regarding nitrate-nitrogen removal. Serious clogging phenomena impacting negatively on the treatment performance and the hydraulic conductivity were not observed. Modelling results were generally poor for the set-up period, adequate for the first 2 years after the set-up period and variable after the diesel spill. The Wang-Scholz model performed well for less complex operations.

  14. Plankton composition, distribution and significance in a tropical integrated pilot constructed treatment wetland in Uganda.

    PubMed

    Luyiga, S; Kiwanuka, S

    2003-01-01

    The importance of the plankton community in wastewater treatment has been under-estimated for a long time, simply because of its biomass accumulation resulting in final release of organic matter back into the system after decomposition. In a two-year 3-month periodical study on a tropical integrated wastewater treatment constructed wetland, the phytoplankton role was tested and it has been shown that, through harvesting, the phytoplankton community plays a significant role in municipal wastewater treatment. The high phytobiomass, which was dominated by green algae (Chlorophyta), enhanced high levels of dissolved oxygen and high pH within the open ponds, and because of this, the system was found to be highly efficient in BOD5 (81%) and NH4+-N (93%) removal. The high pH enhanced ammonia volatilization within the open ponds. Regression statistics between the plankton community composition and some of the physicochemical parameters (BOD, NH4+-N, DO, pH) within the wetland system show a significant relationship. In conclusion, open treatment wetlands provide a wide variety of planktonic organisms as water quality improvement systems through the provision of oxygen and alteration of the pH for BOD5 and ammonium reduction respectively.

  15. Soil bacterial communities in constructed wetlands treated with swine wastewater using PCR-DGGE technique.

    PubMed

    Dong, Xiuli; Reddy, Gudigopuram B

    2010-02-01

    Marsh-pond-marsh (MPM) constructed wetlands were designed for the treatment of swine wastewater. The goal of this study was to characterize bacterial communities in these wetlands and determine the nutrient removal from influent to effluent. Surface soil samples were collected and analyzed by culture-dependent and culture-independent techniques. The results showed that the bacterial colony forming units (CFU) and the average concentrations of total nitrogen, NH(4)(+), total phosphorous (TP) and PO(4)(3-) from the influent to the effluent decreased. The NH(4)(+) and the PO(4)(3-) concentrations showed the most dramatic changes, with decreases of 39.97% and 16.92%, respectively. Data of culture-independent samples produced by using PCR-denaturing gradient gel electrophoresis (DGGE) technique showed that the Shannon diversity index and richness decreased significantly (P<0.05) from influent to effluent. Bacterium species distributions strongly correlated with the concentrations of TP, NH(4)(+) and the PO(4)(3-). Sequencing of partial 16S rRNA genes fragments revealed that the total bacterial community composition was dominated by Pseudomonas sp., Arthrobacter sp., Bacillus sp. and other soil bacteria. Anammox (anaerobic ammonium oxidation) stains were detected. Phylogenetic analysis demonstrated that some of the partial 16S rRNA gene sequences had close relationships with unculturable denitrification bacteria. The activities of these bacteria might contribute to the nutrient removal in the wetlands.

  16. Integrated constructed wetland systems: design, operation, and performance of low-cost decentralized wastewater treatment systems.

    PubMed

    Behrends, L L; Bailey, E; Jansen, P; Houke, L; Smith, S

    2007-01-01

    Several different types of constructed wetland systems are being used as decentralized treatment systems including surface-flow, subsurface-flow, vertical-flow, and hybrid systems. Archetypical wetland systems have design strengths and weaknesses, and therefore it should be possible to design combined (integrated) systems to optimize a number of important treatment processes. This study provides comparative efficacy data for two integrated wetland treatment systems (IWTS) designed to enhance treatment of medium strength wastewater generated from a pilot-scale intensive fish farm. Results from the twenty eight months study included consistently high removal of COD (84% +) and ammonia nitrogen (93%) in both systems. Initially, phosphorus removal was also high (>90%) in both systems, but removal efficacy declined significantly over time. Nitrate removal was significantly better in the system that provided sequential aerobic and anoxic environments. Short hydraulic retention times coupled with sustained removal of COD and ammonia indicate that the ReCip components could be a least-cost wastewater treatment technology in the decentralized market sector.

  17. Carbon sequestration in a surface flow constructed wetland after 12 years of swine wastewater treatment.

    PubMed

    Reddy, Gudigopuram B; Raczkowski, Charles W; Cyrus, Johnsely S; Szogi, Ariel

    2016-01-01

    Constructed wetlands used for the treatment of swine wastewater may potentially sequester significant amounts of carbon. In past studies, we evaluated the treatment efficiency of wastewater in a marsh-pond-marsh design wetland system. The functionality of this system was highly dependent on soil carbon content and organic matter turnover rate. To better understand system performance and carbon dynamics, we measured plant dry matter, decomposition rates and soil carbon fractions. Plant litter decomposition rate was 0.0052 g day(-1) (±0.00119 g day(-1)) with an estimated half-life of 133 days. The detritus layer accumulated over the soil surface had much more humin than other C fractions. In marsh areas, soil C extracted with NaOH had four to six times higher amounts of humic acid, fulvic acid and humin than soil C extracted by cold and hot water, HCl/HF, and Na pyruvate. In the pond area, humic acid, fulvic acid and humin content were two to four times lower than in the marsh area. More soil C and N was found in the marsh area than in the pond area. These wetlands proved to be large sinks for stable C forms.

  18. Microbial density and diversity in constructed wetland systems and the relation to pollutant removal efficiency.

    PubMed

    Zhang, Yang; Carvalho, Pedro N; Lv, Tao; Arias, Carlos; Brix, Hans; Chen, Zhanghe

    2016-01-01

    Microbes are believed to be at the core of the wastewater treatment processes in constructed wetlands (CWs). The aim of this study was to assess the microbial biomass carbon (MBC) and Shannon's diversity index (SDI) in the substrate of CWs planted with Phragmites australis, Hymenocallis littoralis, Canna indica and Cyperus flabelliformis, and to relate MBC and SDI to the pollutant removal in the systems. Significant higher MBC was observed in CWs with H. littoralis and C. indica than in CWs with P. australis, and the MBC differed with season and substrate depth. The microbial community in the wetlands included four phyla: Cyanobacteria, Proteobacteria, Chloroflexi, and Acidobacteria, with a more diverse community structure in wetlands with C. flabelliformis. The MBC in the substrate and the SDI of the 15-20 cm depth correlated with the removal of biochemical oxygen demand, NH4-N and NO3-N. Our results indicate that substrate SDI and MBC can both be regarded as bioindicators of the pollutant removal ability in CWs.

  19. Applying solubilization treatment to reverse clogging in laboratory-scale vertical flow constructed wetlands.

    PubMed

    Guofen, Hua; Wei, Zhu; Lianfang, Zhao; Yunhui, Zhang

    2010-01-01

    Substrate clogging is characterized as a frequently occurring operational problem for subsurface-flow constructed wetlands. The application of solubilization treatment to reduce clogging was tested in lab-scaled setups to provide a promising solution. The performance of solubilization treatment on reducing clogging and the related effects on plants and biofilms in the wetland system were investigated in this paper. The results showed that the infiltration rate and available porosity of wetland substrate increased as a function of increased dosage of NaOH, HCl, NaClO, and detergent, respectively. Among the four solvents, it appeared that NaClO had the most obvious effects on reducing clogging and the infiltration rate and effective porosity recovered to 69% of the original condition. The two possible reasons for solubilization were the flocculents' structure of the clogs was broken up or parts of the organic clogs were dissolved. The function of adding NaOH and NaClO was to dissolve the protein and polysaccharides of the organic clogs; the function of adding HCl was to release the anaerobic gas wrapped in the organic clogs. Furthermore, experiments results also showed that the solubilized solvents did not demonstrate a long-term negative effect on plants and biofilms.

  20. Subsurface-flow constructed wetlands treatment in the plains: five years of experience.

    PubMed

    Dahab, M F; Surampalli, R Y

    2001-01-01

    This paper documents the performance of a subsurface-flow constructed wetlands system during its initial five years of operation under variable loading and operating conditions associated with a northern midwestern US climate. The results indicate that effective and sufficient CW seasonal removals of TSS, VSS, CBOD5, COD, and fecal coliform were achieved. Wastewater temperatures seemed to affect CBOD5 and COD removal rates. Nitrogen and phosphorus reductions were not as effective and varied seasonally, as well as with wastewater temperature. The addition of a sand filter, to aid in further nitrification and disinfection following CW treatment, markedly improved the performance of the wetlands system. After a few years of operation, the remarkable performance of the CW system was dampened by apparent clogging and subsequent eruption of wastewater at the head-end of the treatment cells. While clogging was partially caused by biomass build-up in the wetlands substrate, visual observations suggest that excessive vegetation coupled with relaxed maintenance may also be responsible for clogging.

  1. Wetland assessment of the effects of construction and operation of a depleteduranium hexafluoride conversion facility at the Portsmouth, Ohio, site.

    SciTech Connect

    Van Lonkhuyzen, R.

    2005-09-09

    The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF{sub 6}) Management Program evaluated alternatives for managing its inventory of DUF{sub 6} and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF{sub 6} PEIS) in April 1999 (DOE 1999). The DUF{sub 6} inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF{sub 6} PEIS, DOE stated its decision to promptly convert the DUF{sub 6} inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF{sub 6} conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF{sub 6} cylinders stored at ETTP to the Portsmouth site for conversion. This wetland assessment has been prepared by DOE, pursuant to Executive Order 11990 (''Protection of Wetlands'') and DOE regulations for implementing this Executive Order as set forth in Title 10, Part 1022, of the ''Code of Federal Regulations'' (10 CFR Part 1022 [Compliance with Floodplain and Wetland Environmental Review Requirements]), to evaluate potential impacts to wetlands from the construction and operation of a conversion facility at the DOE Portsmouth site. Approximately 0.02 acre (0.009 ha) of a 0.08-acre (0.03-ha) palustrine emergent wetland would likely be eliminated by direct placement of fill material during facility construction at Location A. Portions of this wetland that are not filled may be indirectly affected by an altered

  2. The performance of constructed wetlands treating primary, secondary and dairy soiled water in Ireland (a review).

    PubMed

    Healy, M G; O' Flynn, C J

    2011-10-01

    In Ireland, no database detailing the design, influent loading rates or performance of constructed wetlands (CWs) exists. On account of this, they are designed without any protocol based on empirical data. The aim of this paper was to provide the first published data on the performance of free-water surface flow (FWSF) CWs treating primary and secondary-treated municipal wastewater, and agricultural dairy soiled water (DSW) in Ireland. In total, the performance of thirty-four FWSF CWs, comprising fourteen CWs treating primary-treated municipal wastewater, thirteen CWs treating secondary-treated municipal wastewater, and seven CWs treating DSW, were examined. In most CWs, good organic, suspended solids (SS) and nutrient removal was measured. At an average organic loading rate (OLR) of 10 and 9 g biochemical oxygen demand (BOD) m(-2) d(-1), CWs treating primary and secondary wastewater removed 95 and 84% of influent BOD. Constructed wetlands treating DSW had an average BOD removal of 98%. At average SS loading rates of 6 and 14 g m(-2) d(-1), CWs treating primary and secondary wastewater had a 96 and an 82% reduction, and produced a final effluent with a concentration of 14 and 13 mg L(-1). Constructed wetlands treating DSW produced a final effluent of 34 mg L(-1) (94% reduction). Similar to other studies, all CWs examined had variable performance in ammonium-N (NH(4)(+)-N) removal, with average removals varying between 37% (for CWs treating secondary wastewater) and 88% (for CWs treating DSW). Variable ortho-phosphorus (PO(4)(3-)-P) removal was attributable to different durations of operation, media types and loading rates.

  3. Macrophyte growth in a pilot-scale constructed wetland for industrial wastewater treatment.

    PubMed

    Hadad, H R; Maine, M A; Bonetto, C A

    2006-06-01

    A pilot-scale wetland was constructed to assess the feasibility of treating the wastewater from a tool industry in Santo Tomé, Santa Fe, Argentina. The wastewater had high conductivity and pH, and contained Cr, Ni and Zn. This paper describes the growth of vegetation in the experimental wetland and the nutrient and metal removal. The wetland was 6 x 3 x 0.4 m. Water discharge was 1000 l d(-1) and residence time was 7d. After the wetland was rendered impermeable, macrophytes from Middle Paraná River floodplain were transplanted. Influent and effluent quality was analyzed every 15 d. TP, Cr, Ni and Zn concentrations in leaves, roots and sediment (inlet and outlet) were measured monthly. Cover and biomass of predominant species were estimated. Also, greenhouse experiments were carried out to measure the effects of conductivity and pH on floating species. The variables measured in the influent were significantly higher than those in the effluent, except for HCO(3)(-) and NH(4)(+). TP and metal concentrations in sediment at the inlet were significantly higher than those at the outlet. Conductivity and pH of the incoming wastewater were toxic for the floating species. Typha domingensis displaced the other species and reached positive relative cover rate and biomass greater than those at the undisturbed natural environment. T. domingensis proved to be highly efficient for the treatment of wastewater. For that reason, it is the advisable species for the treatment of wastewater of high conductivity and pH enriched with metals, characteristic of many industrial processes.

  4. Quantification of oxygen release by bulrush (Scirpus validus) roots in a constructed treatment wetland.

    PubMed

    Bezbaruah, Achintya N; Zhang, Tian C

    2005-02-05

    Amount of oxygen released by bulrush (Scirpus validus) roots has been quantified based on the radial oxygen loss (ROL) exhibited by the roots, the number and the length of active lateral roots, and the field plant density. It was found that wetland bulrush contains two types of active lateral roots (showing ROL), viz., laterals of brown and white main roots. The two laterals have distinct oxygen release characteristics. Based on the dissolved oxygen (DO) microprofiles of brown and white laterals, the ROLs were found to be approximately 61 ng O2 cm(-2) root surface min(-1) and approximately 68 ng O2 cm(-2) root surface min(-1), respectively, at bulk 5-day biochemical oxygen demand (BOD5) of 76 mg L(-1). The respective average active root lengths of the brown and the white laterals were approximately 40 and approximately 1676 microm. Based on field and laboratory measurements, the average amount of oxygen released by bulrush was found to be 2.30 mg O2 m(-2) wetland surface d(-1); of this approximately 71% is from the white roots. The results of this study indicate that plants do not release enough oxygen to meet the total oxygen demand of bulk wastewater, and therefore, constructed wetlands should be designed as an anaerobic or an aerobic-anaerobic hybrid system rather than as an aerobic system. However, the results of this study should be viewed in the background of possible errors (including a reactor design flaw), which might have made the measured oxygen release significantly lower than what plant roots actually release. Further studies are needed to quantify wetland plant oxygen release based on micro-scale measurements. 2004 Wiley Periodicals, Inc.

  5. Efficiency in removing pollutants by constructed wetland purification systems in Poland.

    PubMed

    Samecka-Cymerman, A; Stepien, D; Kempers, A J

    2004-02-27

    The aim of this study was to compare the efficiency between Phragmites communis, Salix viminalis, and Populus canadensis in removing the heavy metals Al, Ba, Mn, Ni, Sr, V, Zn, Cd, Cu, and Pb and the eutrophying macroelements phosphate, nitrate, nitrite, ammonia, chloride, sulfate, Ca, Mg, K, and Fe from sewage in subsurface flow constructed wetlands in Poland. The effectiveness of the sewage treatment system was higher in summer compared to winter for the removal of (1) all heavy metals, phosphate (P) and mineral nitrogen (N) for all of species, (2) sulfates (S) for Phragmites and Salix, (3) iron (Fe) for Salix, and (4) chloride (Cl) for Salix and Populus. Analysis of variance indicated that there was no significant difference between the purifications systems in phytoremediation of Mn; so all species were equally effective (99%, prob. level 0.001). The Salix wetland system was most effective in purification of water and removal of macroelements (24-82% in summer, 10-80% in winter with Fe 97%), Cd (58-71%), V (100%), and Zn (84-92%). The Phragmites system was most effective in purification and removal of Al (81-97%), Ba (70-95%), Pb (64-81%), and Sr (24-51%), while in the case of Cu (49-60%) and Ni (55-67%) the Populus wetland system proved most effective. The outflowing water of the wetlands contained elements in amounts exceeding the admissible levels as established for unpolluted water both in winter and summer. Therefore the effectiveness of the observed phytoremediation systems in this study was not sufficient alone to remove these elements and can be considered as a supplemental tool in purification of sewage.

  6. Treatment of landfill leachate-impacted groundwater using cascade aeration and constructed wetlands

    SciTech Connect

    Loer, J.; O`Flanagan, B.; Fellows, W.

    1995-12-31

    At an unlined municipal solid waste landfill, heavy metal and toxic organic compounds present in leachate have impacted groundwater, necessitating extraction and treatment of the contaminated groundwater. A remedial design relying on a natural systems engineering approach will take advantage of existing contours (gravity flow) and surroundings (wetlands), and will limit energy inputs and eliminate chemical inputs. Impacted groundwater will be extracted, and aerated via a cascade constructed of polypropylene sheets fabricated into {open_quotes}step{close_quotes} sections and set into a side slope of the landfill. Volatilization of organics and oxidation of iron and heavy metals to insoluble compounds will occur during cascading and will continue within a sedimentation basin where settling of iron precipitates will induce co-settling of heavy metal precipitates. Following the sedimentation basin, a constructed wetland containing both aerobic zones and anaerobic zones will provide additional treatment of remaining solids and heavy metals, before surface discharge. Use of a natural systems approach significantly reduces operating costs compared to a mechanical-aeration, chemical-precipitation system, and is more aesthetically pleasing and suited to the remote locale. The system is under construction and seasonal operation will begin in spring 1996.

  7. Study of praziquantel phytoremediation and transformation and its removal in constructed wetland.

    PubMed

    Marsik, P; Podlipna, R; Vanek, T

    2017-02-05

    Accumulation and/or degradation of Praziquantel (PZQ) in plants were determined using Phragmites australis, both suspension cultures and in vitro cultivated plants. In case of initial PZQ concentration 20mgL(-1), 90% was removed from liquid media within 21days. The accumulated PZQ was partly metabolized, twenty one compounds being identified, products of both Phase I and II of detoxification metabolism. Laboratory results were confirmed in real scale using the constructed wetland (CW), where PZQ (500mg in total) was completely removed until the first purification pond. This result offers a promising possibility to use CW for PZQ removal from agricultural as well as domestic waste-waters.

  8. Treatment of laboratory wastewater in a tropical constructed wetland comparing surface and subsurface flow.

    PubMed

    Meutia, A A

    2001-01-01

    Wastewater treatment by constructed wetland is an appropriate technology for tropical developing countries like Indonesia because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The aim of the research is to examine the capability of constructed wetlands for treating laboratory wastewater at our Center, to investigate the suitable flow for treatment, namely vertical subsurface or horizontal surface flow, and to study the effect of the seasons. The constructed wetland is composed of three chambered unplanted sedimentation tanks followed by the first and second beds, containing gravel and sand, planted with Typha sp.; the third bed planted with floating plant Lemna sp.; and a clarifier with two chambers. The results showed that the subsurface flow in the dry season removed 95% organic carbon (COD) and total phosphorus (T-P) respectively, and 82% total nitrogen (T-N). In the transition period from the dry season to the rainy season, COD removal efficiency decreased to 73%, T-N increased to 89%, and T-P was almost the same as that in the dry season. In the rainy season COD and T-N removal efficiencies increased again to 95% respectively, while T-P remained unchanged. In the dry season, COD and T-P concentrations in the surface flow showed that the removal efficiencies were a bit lower than those in the subsurface flow. Moreover, T-N removal efficiency was only half as much as that in the subsurface flow. However, in the transition period, COD removal efficiency decreased to 29%, while T-N increased to 74% and T-P was still constant, around 93%. In the rainy season, COD and T-N removal efficiencies increased again to almost 95%. On the other hand, T-P decreased to 76%. The results show that the constructed wetland is capable of treating the laboratory wastewater. The subsurface flow is more suitable for treatment than the surface flow, and the seasonal changes have effects on the removal efficiency.

  9. Area Estimation and Distribution Analysis of Subsurface Flow Constructed Wetlands at Regional Scale--Take Guangzhou City for Example

    NASA Astrophysics Data System (ADS)

    Yuan, S. X.; Tang, G. L.; Xiong, H. X.; Chen, J.; Yin, X. L.; Huang, G. Q.

    2017-01-01

    In this paper, Area of Constructed Wetlands (CWs) required for treatment of domestic sewage generated by 13 million people was calculated in accordance with the distribution of existing population in Guangzhou City and mathematical model of CWs. By comparing this with land use data, the distribution of constructed wetlands at construction regional scale was simulated with GIS. The results show that, Guangzhou generate about 3.88 million m3 domestic sewage per day, which shall be treated with 59.37 km2 CWs. Assuming that a single wetland bed is 300 m2, total 197,905 wetland beds shall be required in the city. Based on the analysis and statistics on data of second national land survey of Guangzhou City with GIS, there are enough ponds, bare lands, other grasslands and other garden plots in Guangzhou that can be used for construction of regional scale CWs, but the distribution of available lands in different regions is uneven. Constructed wetlands at regional scale are mainly distributed around Baini Channel, Tianma River, Xinjie River, Liuxi River Valley, Zengjiang River Valley and on both sides of the Pearl River through Panyu and Nansha.

  10. Wetland Water Cooling Partnership: The Use of Constructed Wetlands to Enhance Thermoelectric Power Plant Cooling and Mitigate the Demand of Surface Water Use

    SciTech Connect

    Apfelbaum, Steven; Duvall, Kenneth; Nelson, Theresa; Mensing, Douglas; Bengtson, Harlan; Eppich, John; Penhallegon, Clayton; Thompson, Ry

    2013-09-30

    Through the Phase I study segment of contract #DE-NT0006644 with the U.S. Department of Energy’s National Energy Technology Laboratory, Applied Ecological Services, Inc. and Sterling Energy Services, LLC (the AES/SES Team) explored the use of constructed wetlands to help address stresses on surface water and groundwater resources from thermoelectric power plant cooling and makeup water requirements. The project objectives were crafted to explore and develop implementable water conservation and cooling strategies using constructed wetlands (not existing, naturally occurring wetlands), with the goal of determining if this strategy has the potential to reduce surface water and groundwater withdrawals of thermoelectric power plants throughout the country. Our team’s exploratory work has documented what appears to be a significant and practical potential for augmenting power plant cooling water resources for makeup supply at many, but not all, thermoelectric power plant sites. The intent is to help alleviate stress on existing surface water and groundwater resources through harvesting, storing, polishing and beneficially re-using critical water resources. Through literature review, development of conceptual created wetland plans, and STELLA-based modeling, the AES/SES team has developed heat and water balances for conventional thermoelectric power plants to evaluate wetland size requirements, water use, and comparative cooling technology costs. The ecological literature on organism tolerances to heated waters was used to understand the range of ecological outcomes achievable in created wetlands. This study suggests that wetlands and water harvesting can provide a practical and cost-effective strategy to augment cooling waters for thermoelectric power plants in many geographic settings of the United States, particularly east of the 100th meridian, and in coastal and riverine locations. The study concluded that constructed wetlands can have significant positive

  11. IDENTIFICATION EFFICIENCY IN GROUNDWATER ADJACENT TO DITCHES WITHIN CONSTRUCTED RIPARIAN WETLANDS: KANKAKEE WATERSHED, ILLINOIS-INDIANA, U.S.A.

    EPA Science Inventory

    Dual isotope evaluations of NO3 in groundwater adjacent to ditches within constructed riparian wetlands across the Kankakee water-shed may assist the determination of denitrification efficiency. Groundwater sampling indicates the NO3 -N exceeded 10 mg 1-1 in constructed riparian ...

  12. IDENTIFICATION EFFICIENCY IN GROUNDWATER ADJACENT TO DITCHES WITHIN CONSTRUCTED RIPARIAN WETLANDS: KANKAKEE WATERSHED, ILLINOIS-INDIANA, U.S.A.

    EPA Science Inventory

    Dual isotope evaluations of NO3 in groundwater adjacent to ditches within constructed riparian wetlands across the Kankakee water-shed may assist the determination of denitrification efficiency. Groundwater sampling indicates the NO3 -N exceeded 10 mg 1-1 in constructed riparian ...

  13. Pre-Construction Biogeochemical Analysis of Mercury in Wetlands Bordering the Hamilton Army Airfield (HAAF) Wetlands Restoration Site. Part 2

    DTIC Science & Technology

    2007-09-01

    recovery of PCB-contaminated surface sediments at the Sangamo-Weston Twelvemile Creek/ Lake Hartwell Superfund Site. Environ. Sci. Technol. 15:2328-2337...subsidence such that current soil elevations are often meters below the mean tide level. Simply breaching the dikes would result in lakes , not wetlands...certain natural wetlands have been identified as contributors of MeHg to down- stream lakes and streams (St. Louis et al. 1994; St. Louis et al. 1996

  14. Evapotranspiration from pilot-scale constructed wetlands planted with Phragmites australis in a Mediterranean environment.

    PubMed

    Milani, Mirco; Toscano, Attilio

    2013-01-01

    This article reports the results of evapotranspiration (ET) experiments carried out in Southern Italy (Sicily) in a pilot-scale constructed wetland (CW) made of a combination of vegetated (Phragmites australis) and unvegetated sub-surface flow beds. Domestic wastewater from a conventional wastewater treatment plant was used to fill the beds. Microclimate data was gathered from an automatic weather station close to the experimental plant. From June to November 2009 and from April to November 2010, ET values were measured as the amount of water needed to restore the initial volume in the beds after a certain period. Cumulative reference evapotranspiration (ET(0)) was similar to the cumulative ET measured in the beds without vegetation (ET(con)), while the Phragmites ET (ET (phr) ) was significantly higher underlining the effect of the vegetation. The plant coefficient of P. australis (K(p)) was very high (up to 8.5 in August 2009) compared to the typical K(c) for agricultural crops suggesting that the wetland environment was subjected to strong "clothesline" and "oasis" effects. According to the FAO 56 approach, K(p) shows different patterns and values in relation to growth stages correlating significantly to stem density, plant height and total leaves. The mean Water Use Efficiency (WUE) value of P. australis was quite low, about 2.27 g L(-1), probably due to the unlimited water availability and the lack of the plant's physiological adaptations to water conservation. The results provide useful and valid information for estimating ET rates in small-scale constructed wetlands since ET is a relevant issue in arid and semiarid regions. In these areas CW feasibility for wastewater treatment and reuse should also be carefully evaluated for macrophytes in relation to their WUE values.

  15. Optimal conditions for chlorothalonil and dissolved organic carbon in horizontal subsurface flow constructed wetlands.

    PubMed

    Rìos-Montes, Karina A; Casas-Zapata, Juan C; Briones-Gallardo, Roberto; Peñuela, Gustavo

    2017-01-13

    The most efficient system of horizontal subsurface flow constructed wetlands (HSSFCW) for removing dissolved organic carbon (DOC) in the presence of chlorothalonil pesticide (CLT) present in synthetic domestic wastewater was determined using the macrophyte Phragmites australis. Two concentrations of CLT (85 and 385 μg L(-1)) and one concentration of glucose (20 mg L(-1)) were evaluated in four pilot scale horizontal surface flow constructed wetlands coupled with two sizes of silica gravel, igneous gravel, fine chalky gravel (3.18-6.35 mm), coarse gravel (12.70-25.40 mm) and two water surface heights (20 and 40 cm). For a month, wetlands were acclimated with domestic wastewater. Some groups of bacteria were also identified in the biofilm attached to the gravel. In each treatment periodic samplings were conducted in the influent and effluent. Chlorothalonil was quantified by gas chromatography (GC-ECD m), DOC by an organic carbon analyzer and bacterial groups using conventional microbiology in accordance with Standard Methods. The largest removals of DOC (85.82%-85.31%) were found when using fine gravel (3.18-6.35 mm) and the lower layer of water (20 cm). The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, Pseudomonas and total coliforms. The results of this study indicate that fine grain gravel (3.18-6.35 mm) and both water levels (20 to 40 cm) can be used in the removal of organic matter and for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT in HSSFCW.

  16. Structure and function of the bacterial communities during rhizoremediation of hexachlorobenzene in constructed wetlands.

    PubMed

    Zhang, Cuiping; Wang, Bei; Dai, Xiaoyan; Li, Shuying; Lu, Guangqiu; Zhou, Yuanqing

    2017-04-01

    Vertical flow constructed wetlands (VF CWs) are considered to be effective for treating organic pollutants. The rhizosphere of macrophytes such as Phragmites sp., Typha sp. serves as an active and dynamic zone for the microbial degradation of organic pollutants. However, it is still not clear how soil bacterial communities respond to macrophytes and pollutants during the process. For this purpose, the seedlings of Phragmites australis and Typha angustifolia were planted respectively in the VF CWs added with HCB at a dose of 2 mg/kg. During 96 days of cultivation, we monitored hexachlorobenzene (HCB) removal efficiency by GC/MS and the structure of the rhizosphere bacterial communities in the different VF CWs by denaturing gradient gel electrophoresis (DGGE), and constructed bacterial clone library based on PCR-amplified 16S rRNA gene. As expected, the rhizosphere bacterial communities also remained insensitive to HCB exposure in the wetland soil. The diversity of these microbes presented two stages, from the varied up and down to equilibrium in the entire experimental period. Molecular analysis revealed that the phylum Firmicutes dominated over the bacterial communities. The genera that increased under HCB stress included the well-known HCB-degrading bacteria (Pseudomonas sp. and Alcaligenes sp.) and other common bacteria found in contaminated soil but with lesser known practical functions (Burkholderia sp., Lysinibacillus fusiformis, and Bacillus cereus). Furthermore, there was a certain variance in the relative abundances of the bacterial phyla and HCB removal efficiency among different VF CW treatments. The degradation of HCB in T. angustifolia microcosms was faster than that in P. australis and unvegetated wetlands, and the highest bacterial diversity and richness was found in the VF CWs comprising T. angustifolia.

  17. Elimination of pharmaceuticals and personal care products in subsurface flow constructed wetlands.

    PubMed

    Matamoros, Victor; Bayona, Josep M

    2006-09-15

    Removal efficiency and elimination rates of 11 pharmaceuticals and personal care products (PPCPs)were measured in two subsurface horizontal flow constructed wetlands (SSFs) characterized by different water depths (i.e. 0.3 and 0.5 m) in a 2-year study. Dissolved and particulate phases of wastewater and gravel samples were collected and analyzed. The PPCP influent concentration ranged from 1 to 25 microg L(-1). The best removal efficiency was found in the shallower bed SSF due to its less negative redox potential. PPCPs were classified in four groups according to their removal behavior: (i) the efficiently removed (>80%) namely caffeine, salicylic acid, methyl dihydrojasmonate, and carboxy-ibuprofen, (ii) the moderately removed (50-80%) namely ibuprofren, hydroxy-ibuprofen, and naproxen, (iii) the recalcitrant to the elimination namely ketoprofen and diclofenac, and,finally, (iv) compounds that were eliminated by hydrophobic interactions namely polycyclic musks (i.e. galaxolide and tonalide). These compounds were removed more than 80% from the effluent but occurred at high concentrations (up to 824 microg kg(-1)) in the gravel bed. Accordingly, their elimination by sorption onto the organic matter retained is the predominant removal mechanism. Furthermore, the constructed wetland clogging appears to induce a negative effect in the PPCP degradation in the SSF evaluated. The PPCP elimination classified as efficiently and moderately removed through the shallow bed fitted to either zero- or a first-order areal kinetics. Finally, the apparent distribution coefficients between suspended solids (Kd'ss) or gravel bed (Kd'gb) and water were determined in the different sampling points of the wetland obtaining values comparable to the described previously for sewage sludge.

  18. Effects of the substrate depth on purification performance of a hybrid constructed wetland treating domestic sewage.

    PubMed

    Ren, Yong-Xiang; Zhang, Hai; Wang, Chao; Yang, Yong-Zhe; Qin, Zhen; Ma, Yun

    2011-01-01

    The depth of substrate in constructed wetlands (CWs) has a significant effect on the construction investment and the purification performance of CWs. In this study, a pilot scale CW system was operated in a domestic sewage treatment plant in Xi'an, China. The experimental systems included three-series CWs systems with substrate depths of 0.1m, 0.3 m and 0.6 m, respectively. Each series was composed of a hydroponic ditch, a horizontal subsurface flow CW and a vertical flow CW. The effluent from the primary clarifier in the sewage treatment plant was intermittently conducted to the wetlands at a flow rate of 0.3 m(3)/d. The hydraulic loading rate of each CWs system was regulated at 0.1 m(3)/m(2).d and the hydraulic retention time was 3 days. Canna indica L. was planted both in the hydroponic ditches and the CWs systems. Results showed that the highest removal efficiency of NH(+)(4)-N and TP was obtained in the hybrid CW with 0.1 m substrate depth. The average removal efficiency for NH(+)(4)-N and TP were 90.6 % and 80.0 %, respectively. The highest average removal efficiency of COD was obtained in hybrid CWs system with 0.6 m substrate depth. Therefore, a simultaneous removal of COD and nutrients can be achieved through the combination of different wetlands using different substrate depths. In addition, the substrate depth presents significant effects on the concentration of DO and root growth characteristics of canna in the system. As a result, the highest concentration of DO (>2 mg/L) and the highest amount of roots production were achieved in the 0.1 m substrate depth horizontal and vertical flow CWs.

  19. Comparing the efficiency of Cyperus alternifolius and Phragmites australis in municipal wastewater treatment by subsurface constructed wetland.

    PubMed

    Shahi, Davod Hossein; Eslami, Hadi; Ehrampoosh, Mohamad Hasan; Ebrahimi, Asghar; Ghaneian, Mohamad Taghy; Ayatollah, Shirin; Mozayan, Mohamad Reza

    2013-04-15

    Nowadays, application of natural wastewater treatment systems such as wetland not only reduces economic costs and energy consumption, but also decreases environmental pollution. This study aimed to compare efficiency of Cyperus alternifolius and Phragmites australis in Municipal wastewater treatment by Subsurface Constructed Wetland Method. This is an applied-interventionnal study in which three reactors (control pilot, Cyperus alternifolius (umbrella palm) plant pilot and Phragmites australis (reed) plant pilot were designed by subsurface constructed wetland method. Then 90 samples were taken from input and output of reactors with four-day retention time. These samples were tested and finally the data were analyzed by Paired Sample Test statistical analysis. The results showed that removal efficiency of the parameters such as COD, BOD5, TSS, NO3-N, NH3-N, PO4-P, total coliform and fecal coliform was 74, 73, 84, 40, 36, 70, 33 and 38% in Cyperus alternifolius plant wetland, 44, 34, 77, 15, 0.3, 1, 17 and 26% in control wetland and 59, 54, 73, 6, 3, 10, 93 and 50 in Phragmites australis plant wetland, respectively. This reduction rate in all parameters- except fecal coliform- was statistically significant (p = 0.05). The results of this study showed that Cyperus alternifolius plant had higher efficiency in the removal of chemical parameters, whereas Phragmites australis plant had appropriate efficiency in the removal of microbiological parameters. Therefore, it can be concluded that application of these two plants can be effective in wastewater treatment.

  20. Norflurazon and simazine removal from surface water using a constructed wetland.

    PubMed

    Wilson, P Chris; Lu, Hai; Lin, Youjian

    2011-10-01

    Norflurazon and simazine are pre-emergent herbicides detected frequently in surface water associated with South Florida agricultural canals and drainage water. This study investigated the potential use of a 1.34 ha constructed wetland for removing these herbicides from surface water. The total length of the wetland was 400 m and width was 35 m. A surface water flow rate of 740 L/min was maintained in the system using a pump. The plant community within the system consisted primarily of Panicum repens, Alternanthera philoxeroides, and Bacopa caroliniana. Norflurazon and simazine, derived from commercial formulations, were injected (51.1 g active ingredient each) directly into the water pumped into the wetland over a 2 h period. Water samples were collected from the wetland upstream of the dosing system at 3 h intervals from the beginning through 360 h and at the exit point at 1, 2, and 3 h intervals for the periods of 0-24, 25-48 and 49-360 h after dosing, respectively. The herbicides were extracted using C-18 cartridges and were analyzed by GC-TSD. The total mass of each herbicide discharged from the system was estimated by multiplying the concentration by the total volume discharged during the sampled period. Neither herbicide was detected in the inflow water during the entire study. Norflurazon was first detected at the exit 19 h after dosing and simazine after 23 h. Discharge patterns of the two herbicides differed dramatically. Norflurazon tended to bleed off from the wetland with no distinct peak concentration. However, the mobile fraction of simazine was discharged over a 58 h period. Mean/maximum/median detectable concentrations of the herbicides were 3.9 ± 1.7/8.1/3.4 μg L(-1) for norflurazon, and 11.9 ± 6.8/23.6/12.0 μg L(-1) for simazine, respectively. The total masses of norflurazon and simazine discharged from the exit during the 15 day study were 51.7 and 26.9 g, indicating 0% and 47.4% removal from the surface water by the system. © Springer

  1. The role of free water surface constructed wetlands as polishing step in municipal wastewater reclamation and reuse.

    PubMed

    Ghermandi, A; Bixio, D; Thoeye, C

    2007-07-15

    In Europe, the last two decades witnessed growing water stress, both in terms of water scarcity and quality deterioration, which prompted many municipalities for a more efficient use of the water resources, including a more widespread acceptance of water reuse practices. Treatment technology encompasses a vast variety of options. Constructed wetlands are regarded as key elements in polishing conventionally treated wastewater for recreational and environmental applications. A survey was conducted to assess the performance of tertiary free water surface constructed wetlands in treating both key and emerging contaminant categories in the perspective of water reuse. A database was created with information concerning systems with emerging and free-floating macrophytes. The database includes results from both full- and pilot-scale systems, and considers a broad variety of operating conditions. This paper provides an overview of the treatment performances of the constructed wetlands in the database and discusses their significance in the optic of water reclamation and reuse practices.

  2. Intensified nitrogen removal in immobilized nitrifier enhanced constructed wetlands with external carbon addition.

    PubMed

    Wang, Wei; Ding, Yi; Wang, Yuhui; Song, Xinshan; Ambrose, Richard F; Ullman, Jeffrey L

    2016-10-01

    Nitrogen removal performance response of twelve constructed wetlands (CWs) to immobilized nitrifier pellets and different influent COD/N ratios (chemical oxygen demand: total nitrogen in influent) were investigated via 7-month experiments. Nitrifier was immobilized on a carrier pellet containing 10% polyvinyl alcohol (PVA), 2.0% sodium alginate (SA) and 2.0% calcium chloride (CaCl2). A batch experiment demonstrated that 73% COD and 85% ammonia nitrogen (NH4-N) were degraded using the pellets with immobilized nitrifier cells. In addition, different carbon source supplement strategies were applied to remove the nitrate (NO3-N) transformed from NH4-N. An increase in COD/N ratio led to increasing reduction in NO3-N. Efficient nitrification and denitrification promoted total nitrogen (TN) removal in immobilized nitrifier biofortified constructed wetlands (INB-CWs). The results suggested that immobilized nitrifier pellets combined with high influent COD/N ratios could effectively improve the nitrogen removal performance in CWs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Intensified nitrate and phosphorus removal in an electrolysis -integrated horizontal subsurface-flow constructed wetland.

    PubMed

    Gao, Y; Xie, Y W; Zhang, Q; Wang, A L; Yu, Y X; Yang, L Y

    2017-01-01

    A novel electrolysis-integrated horizontal subsurface-flow constructed wetland system (E-HFCWs) was developed for intensified removal of nitrogen and phosphorus contaminated water. The dynamics of nitrogen and phosphorus removal and that of main water qualities of inflow and outflow were also evaluated. The hydraulic retention time (HRT) greatly enhanced nitrate removal when the electrolysis current intensity was stabilized at 0.07 mA/cm(2). When the HRT ranged from 2 h to 12 h, the removal rate of nitrate increased from 20% to 84%. Phosphorus (P) removal was also greatly enhanced-exceeding 90% when the HRT was longer than 4 h in the electrolysis-integrated HFCWs. This improved P removal is due to the in-situ formation of ferric ions by anodizing of sacrificial iron anodes, causing chemical precipitation, physical adsorption and flocculation of phosphorus. Thus, electrolysis plays an important role in nitrate and phosphorus removal. The diversity and communities of bacteria in the biofilm of substrate was established by the analysis of 16S rDNA gene sequences, and the biofilm was abundant with Comamonadaceae and Xanthomonadaceae bacteria in E-HFCWs. Test results illustrated that the electrolysis integrated with horizontal subsurface-flow constructed wetland is a feasible and effective technology for intensified nitrogen and phosphorus removal. Copyright © 2016. Published by Elsevier Ltd.

  4. Treatment performance of a constructed wetland during storm and non-storm events in Korea.

    PubMed

    Maniquiz, M C; Lee, S Y; Choi, J Y; Jeong, S M; Kim, L H

    2012-01-01

    The efficiency of a free water surface flow constructed wetland (CW) in treating agricultural discharges from stream was investigated during storm and non-storm events between April and December, 2009. Physico-chemical and water quality constituents were monitored at five sampling locations along the flow path of the CW. The greatest reduction in pollutant concentration was observed after passing the sedimentation zone at approximately 4% fractional distance from the inflow. The inflow hydraulic loading, flow rates and pollutant concentrations were significantly higher and variable during storm events than non-storm (baseflow) condition (p <0.001) that resulted to an increase in the average pollutant removal efficiencies by 10 to 35%. The highest removal percentages were attained for phosphate (51 ± 22%), ammonium (44 ± 21%) and phosphorus (38 ± 19%) while nitrate was least effectively retained by the system with only 25 ± 17% removal during non-storm events. The efficiency of the system was most favorable when the temperature was above 15 °C (i.e., almost year-round except the winter months) and during storm events. Overall, the outflow water quality was better than the inflow water quality signifying the potential of the constructed wetland as a treatment system and capability of improving the stream water quality.

  5. Treatment of domestic wastewater by vertical flow constructed wetland planted with umbrella sedge and Vetiver grass.

    PubMed

    Kantawanichkul, Suwasa; Sattayapanich, Somsiri; van Dien, Frank

    2013-01-01

    The aim of this study was to investigate the efficiency of wastewater treatment by vertical flow constructed wetland systems under different hydraulic loading rates (HLR). The comparison of two types of plants, Cyperus alternifolius (Umbrella sedge) and Vetiveria zizanioides (Vetiver grass), was also conducted. In this study, six circular concrete tanks (diameter 0.8 m) were filled with fine sand and gravel to the depth of 1.23 m. Three tanks were planted with Umbrella sedge and the other three tanks were planted with Vetiver grass. Settled domestic wastewater from Chiang Mai University (chemical oxygen demand (COD), NH4(+)-N and suspended solids (SS) of 127.1, 27.4 and 29.5 mg/L on average, respectively) was intermittently applied for 45 min and rested for 3 h 15 min. The HLR of each tank was controlled at 20, 29 and 40 cm/d. It was found that the removal efficiency of the Umbrella sedge systems was higher than the Vetiver grass systems for every parameter, and the lowest HLR provided the maximum treatment efficiency. The removal efficiency of COD and nitrogen in terms of total Kjeldahl nitrogen (TKN) was 76 and 65% at 20 cm/d HLR for Umbrella sedge compared to only 67 and 56% for Vetiver grass. Nitrogen accumulation in plant biomass was also higher in Umbrella sedge than in Vetiver grass in every HLR. Umbrella sedge was thus proved to be a suitable constructed wetland plant in tropical climates.

  6. Treatment of Oil Wastewater and Electricity Generation by Integrating Constructed Wetland with Microbial Fuel Cell.

    PubMed

    Yang, Qiao; Wu, Zhenxing; Liu, Lifen; Zhang, Fengxiang; Liang, Shengna

    2016-11-01

    Conventional oil sewage treatment methods can achieve satisfactory removal efficiency, but energy consumption problems during the process of oil sewage treatment are worth attention. The integration of a constructed wetland reactor and a microbial fuel cell reactor (CW-MFC) to treat oil-contaminated wastewater, compared with a microbial fuel cell reactor (MFC) alone and a constructed wetland reactor (CW) alone, was explored in this research. Performances of the three reactors including chemical oxygen demand (COD), oil removal, and output voltage generation were continuously monitored. The COD removals of three reactors were between 73% and 75%, and oil removals were over 95.7%. Compared with MFC, the CW-MFC with a MnO₂ modified cathode produced higher power density and output voltage. Maximum power densities of CW-MFC and MFC were 3868 mW/m³ (102 mW/m²) and 3044 mW/m³ (80 mW/m²), respectively. The plants in CW-MFC play a positive role for reactor cathode potential. Both plants and cathode modification can improve reactor performance of electricity generation.

  7. Treatment performances of French constructed wetlands: results from a database collected over the last 30 years.

    PubMed

    Morvannou, A; Forquet, N; Michel, S; Troesch, S; Molle, P

    2015-01-01

    Approximately 3,500 constructed wetlands (CWs) provide raw wastewater treatment in France for small communities (<5,000 people equivalent). Built during the past 30 years, most consist of two vertical flow constructed wetlands (VFCWs) in series (stages). Many configurations exist, with systems associated with horizontal flow filters or waste stabilization ponds, vertical flow with recirculation, partially saturated systems, etc. A database analyzed 10 years earlier on the classical French system summarized the global performances data. This paper provides a similar analysis of performance data from 415 full-scale two-stage VFCWs from an improved database expanded by monitoring data available from Irstea and the French technical department. Trends presented in the first study are confirmed, exhibiting high chemical oxygen demand (COD), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) removal rates (87%, 93% and 84%, respectively). Typical concentrations at the second-stage outlet are 74 mgCOD L(-1), 17 mgTSS L(-1) and 11 mgTKN L(-1). Pollutant removal performances are summarized in relation to the loads applied at the first treatment stage. While COD and TSS removal rates remain stable over the range of applied loads, the spreading of TKN removal rates increases as applied loads increase.

  8. Hydrodynamic modelling of free water-surface constructed storm water wetlands using a finite volume technique.

    PubMed

    Zounemat-Kermani, Mohammad; Scholz, Miklas; Tondar, Mohammad-Mahdi

    2015-01-01

    One of the key factors in designing free water-surface constructed wetlands (FWS CW) is the hydraulic efficiency (λ), which depends primarily on the retention time of the polluted storm water. Increasing the hydraulic retention time (HRT) at various flow levels will increase λ of the overall constructed wetland (CW). The effects of characteristic geometric features that increase HRT were explored through the use of a two-dimensional depth-average hydrodynamic model. This numerical model was developed to solve the equations of continuity and motions on an unstructured triangular mesh using the Galerkin finite volume formulation and equations of the k-ε turbulence model. Eighty-nine diverse forms of artificial FWS CW with 11 different aspect ratios were numerically simulated and subsequently analysed for four scenarios: rectangular CW, modified rectangular CW with rounded edges, different inlet/outlet configurations of CW, and surface and submerged obstructions in front of the inlet part of the CW. Results from the simulations showed that increasing the aspect ratio has a direct influence on the enhancement of λ in all cases. However, the aspect ratio should be at least 9 in order to achieve an appropriate rate for λ in rectangular CW. Modified rounded rectangular CW improved λ by up to 23%, which allowed for the selection of a reduced aspect ratio. Simulation results showed that CW with low aspect ratios benefited from obstructions and optimized inlet/outlet configurations in terms of improved HRT.

  9. Alternative organic substrates in constructed wetlands: Preliminary results of batch examination

    SciTech Connect

    Mercer, M.N.; Nairn, R.W.

    1999-07-01

    Bacterial sulfate reduction (BSR) can be a major contributor to the generation of alkalinity in some acid mine drainage (AMD) passive treatment systems. BSR requires anaerobic conditions, adequate sulfate concentrations, pH >4, and sufficient labile organic carbon. Hundreds of compost wetlands containing organic substrates have been constructed to treat AMD over the past two decades. Spent mushroom substrate (SMS) has been the most common substrate utilized, in part because of its ready availability in the Northern Appalachian coalfields. In areas where SMS is not readily accessible, such as the southeastern Oklahoma coal mining regions, alternative organic substrates are needed for the construction of effective passive treatment systems. This study examines the possibility of using several alternative organic substrates in AMD treatment wetlands for the generation of alkalinity. Alternative substrates were chosen due to their local availability and abundance. Water quality changes were monitored in microcosms containing six organic substrates (SMS, 100% horse manure, 100% cow manure, a horse manure/sawdust/straw mixture, an 80% cow manure/20% sawdust mixture by mass, and broiler house chicken litter) in bench-scale, batch experiments over a period of two months.

  10. Studies on the phosphorus sorption capacity of substrates used in constructed wetland systems.

    PubMed

    Xu, Defu; Xu, Jianming; Wu, Jianjun; Muhammad, Akmal

    2006-04-01

    Langmuir sorption isotherm was used to screen various substrates for use in removing phosphorus (P) in constructed wetlands (CW). The nine tested substrates included four sands, two soils, bentonite, and two industrial by-products of furnace slag and fly ash. Results showed that the furnace slag had the highest P sorption capacity (8.89 g Pk g(-1)), followed was the fly ash (8.81 g P kg(-1)), and that of sand II was the lowest. Different kinds of sands also showed varying P sorption capacity (0.13-0.29 g P kg(-1)). P sorption capacity was influenced by both the physico-chemical characteristics of the substrates and the amount of organic matter (OM) added. Lifetime of sand II for P sorption estimated by Langmuir P sorption maximum was up to only 9 months in full-scale systems, while that of furnace slag could be used for up to 22 yr. Furnace slag has great potential as a CW substrate, due to its high P sorption capacity. The expected lifetime of constructed wetlands for P removal is strongly influenced by the choice of adsorbing substrate.

  11. Halophytes as vertical-flow constructed wetland vegetation for domestic wastewater treatment.

    PubMed

    Fountoulakis, M S; Sabathianakis, G; Kritsotakis, I; Kabourakis, E M; Manios, T

    2017-04-01

    Recent findings show that halophytes have the ability to accumulate salts in their tissues, making them a very interesting group of plants for domestic wastewater treatment in constructed wetlands (CWs). In that case, it might be possible to reduce the salinity of the final effluent, which is a crucial parameter for wastewater reuse in agriculture. During this study three halophytes, Atriplex halimus, Juncus acutus and Sarcocornia perennis, were tested for phyto-desalination of domestic wastewater in a vertical flow constructed wetland (VFCW) and compared with common reeds (Phragmites australis). In addition, the effect of this alternative vegetation on the overall performance of the system regarding organic matter, nutrients, boron and pathogen removal was monitored. The organic loading rate (OLR) was about 21gCOD/m(2)/d and the hydraulic loading rate (HLR) was 95mm/d in both cases. Promising results were obtained for A. halimus, which shows high biomass productivity and significant capability to accumulate salts, mainly Na, in its tissues. A positive effect on pathogen removal efficiency was also recorded. However, nitrogen concentration in the effluent of the VFCW planted with halophytes was found to be higher than in the effluent of the VFCW planted with reeds. Finally, no significant effect on organic matter and phosphorus removal efficiency was observed from the use of halophytes in place of reeds.

  12. Comparison of grey water treatment performance by a cascading sand filter and a constructed wetland.

    PubMed

    Kadewa, W W; Le Corre, K; Pidou, M; Jeffrey, P J; Jefferson, B

    2010-01-01

    A novel unplanted vertical flow subsurface constructed wetland technology comprising three shallow beds (0.6 m length, 0.45 m width and 0.2 m depth) arranged in a cascading series and a standard single-pass Vertical Flow Planted Constructed Wetland (VFPCW, 6 m² and 0.7 m depth) were tested for grey water treatment. Particular focus was on meeting consent for published wastewater reuse parameters and removal of anionic surfactants. Treatment performance at two hydraulic loading rates (HLR) of 0.08, and 0.17 m³ m⁻² d⁻¹ were compared. Both technologies effectively removed more than 90% turbidity and more than 96% for organics with the prototype meeting the most stringent reuse standard of < 2 NTU and <10 mg/L. However, surfactant removal in the VFPCW was higher (76-85%) than in the prototype which only achieved more than 50% removal at higher loading rate. Generally, the prototype performed consistently better than the VFPCW except for surfactant removal. However, at higher loading rates, both systems did not meet the reuse standard of <1 mg L⁻¹ for anionic surfactants. This observation confirms that shallow beds provide a more oxidised environment leading to higher BOD₅ and COD removals. Presence of plants in the VFPCW led to higher anionic surfactant removal, through increased microbial and sorption processes.

  13. Comparison of horizontal and vertical constructed wetland systems for landfill leachate treatment.

    PubMed

    Yalcuk, Arda; Ugurlu, Aysenur

    2009-05-01

    The main purpose of this study was to treat organic pollution, ammonia and heavy metals present in landfill leachate by the use of constructed wetland systems and to quantify the effect of feeding mode. The effect of different bedding material (gravel and zeolite surface) was also investigated. A pilot-scale study was conducted on subsurface flow constructed wetland systems operated in vertical and horizontal mode. Two vertical systems differed from each other with their bedding material. The systems were planted with cattail (Typha latifolia) and operated identically at a flow rate of 10 l/day and hydraulic retention times of 11.8 and 12.5 day in vertical 1, vertical 2 and horizontal systems, respectively. Concentration based average removal efficiencies for VF1, VF2 and HF were NH(4)-N, 62.3%, 48.9% and 38.3%; COD, 27.3%, 30.6% and 35.7%; PO(4)-P, 52.6%, 51.9% and 46.7%; Fe(III), 21%, 40% and 17%, respectively. Better NH(4)-N removal performance was observed in the vertical system with zeolite layer than that of the vertical 2 and horizontal system. In contrast, horizontal system was more effective in COD removal.

  14. Experimental study of bentonite-soil mixtures as anti-seepage materials of constructed wetlands.

    PubMed

    Chen, Jing; Li, Zifu; Zhao, Xin; Li, Haihan

    2011-01-01

    In this study, mixtures of different kinds of bentonite and soil were used and tested in order to find a cheap alternative to current anti-seepage materials for constructed wetlands. The anti-seepage layer of constructed wetlands was simulated in the experimental study and the permeability coefficient of the mixed materials was determined in order to evaluate the anti-seepage effect of mixtures. The main results are as follows: (i) The minimum mass ratio of bentonite to soil is 10%; (ii) Within a certain range, the more compact and higher the wet density is, then the better anti-seepage effect is (under the condition of certain moisture content). The permeability coefficient of the mixed materials exponentially increased with the increase of wet density; (iii) At the wet density of 1.83 g/cm(3), corresponding with the optimum compactness, the mixture of natural sodium bentonite produced in Wyoming, USA and soil from Cangzhou, Hebei province showed the best anti-seepage performance; (iv) The impermeability of the mixture with smaller particle sizes of bentonite was far better than that with the bigger particle sizes; (v) The hydration effect of bentonite changed the structure of the mixture materials into a special structure that is similar to that of pure bentonite. The particles of the mixture became expanded under SEM investigation and the mixture became more compact, which could have the same or similar effect as pure bentonite for anti-seepage.

  15. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosm.

    PubMed

    Lizotte, Richard E; Testa, Sam; Locke, Martin A; Steinriede, R Wade

    2013-10-01

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures, such as nutrients only (NO) (nitrogen [N], phosphorus [P]), pesticides only (PO) (atrazine, S-metolachlor, permethrin), and nutrients + pesticides on phytoplankton chlorophyll-a, on 48-h aqueous Hyalella azteca survival and 10-day sediment H. azteca survival and growth. Water and sediment were collected at 10-, 20-, and 40-m distances from inflow and analyzed for nutrients, pesticides, chlorophyll-a, and H. azteca laboratory bioassays. Phytoplankton chlorophyll-a increased 4- to 10 -fold at 7 days after NO treatment. However, responses of chlorophyll-a to PO and nutrients + pesticides were more complex with associated decreases at only 20 m for pesticides only and 10 and 40 m for nutrients + pesticides treatments. H. azteca aqueous survival decreased within the first 48 h of dosing at 10- and 20-m distances during PO and nutrients + pesticides treatments in association with permethrin concentrations. H. azteca sediment survival was unaffected, whereas 10-day growth decreased within 1 day of dosing at all sites during nutrients + pesticides treatment. Constructed wetlands were shown to be an effective agricultural best-management tool for trapping pollutants and mitigating ecological impacts of run-off in agricultural watersheds.

  16. Biological Cr(VI) removal using bio-filters and constructed wetlands.

    PubMed

    Michailides, Michail K; Sultana, Mar-Yam; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Vayenas, Dimitrios V

    2013-01-01

    The bioreduction of hexavalent chromium from aqueous solution was carried out using suspended growth and packed-bed reactors under a draw-fill operating mode, and horizontal subsurface constructed wetlands. Reactors were inoculated with industrial sludge from the Hellenic Aerospace Industry using sugar as substrate. In the suspended growth reactors, the maximum Cr(VI) reduction rate (about 2 mg/L h) was achieved for an initial concentration of 12.85 mg/L, while in the attached growth reactors, a similar reduction rate was achieved even with high initial concentrations (109 mg/L), thus confirming the advantage of these systems. Two horizontal subsurface constructed wetlands (CWs) pilot-scale units were also built and operated. The units contained fine gravel. One unit was planted with common reeds and one was kept unplanted. The mean influent concentrations of Cr(VI) were 5.61 and 5.47 mg/L for the planted and unplanted units, respectively. The performance of the planted CW units was very effective as mean Cr(VI) removal efficiency was 85% and efficiency maximum reached 100%. On the contrary, the unplanted CW achieved very low Cr(VI) removal with a mean value of 26%. Both attached growth reactors and CWs proved efficient and viable means for Cr(VI) reduction.

  17. Potential use of mangroves as constructed wetland for municipal sewage treatment in Futian, Shenzhen, China.

    PubMed

    Yang, Q; Tam, N F Y; Wong, Y S; Luan, T G; Su, W S; Lan, C Y; Shin, P K S; Cheung, S G

    2008-01-01

    A pilot-scale mangrove wetland was constructed in Futian, Shenzhen for municipal sewage treatment. Three identical belts (length: 33m, width: 3m, depth: 0.5m) were filled with stone (bottom), gravel and mangrove sand (surface). Seedlings of two native mangrove species (Kandelia candel, Aegiceras corniculatum) and one exotic species (Sonneratia caseolaris) were transplanted to the belts with one species for each belt. The hydraulic loading was 5m(3)d(-1) and hydraulic retention time 3d. High levels of removal of COD, BOD(5), TN, TP and NH(3)-N were obtained. The treatment efficiency of S. caseolaris and A. corniculatum was higher than that of K. candel. Faster plant growth was obtained for S. caseolaris. The substrate in the S. caseolaris belt also showed higher enzyme activities including dehydrogenase, cellulase, phosphatase, urease and beta-glucosidase. The removal rates of organic matter and nutrients were positively correlated with plant growth. The results indicated that mangroves could be used in a constructed wetland for municipal sewage treatment, providing post-treatment to remove coliforms was also included.

  18. Treating surface water with low nutrients concentration by mixed substrates constructed wetlands.

    PubMed

    Li, Chun J; Wan, Ming H; Dong, Yang; Men, Zhen Y; Lin, Yan; Wu, De Y; Kong, Hai N

    2011-01-01

    Constructed wetland (CW) has been widely applied in nutrients reduction for eutrophication control, especially in the advanced treatment of effluent of municipal sewage plants or the in-lake river treatment with high hydraulic loads and low nutrient concentrations. But in real application, it shows lower nutrient removal efficiency. The main reason is that traditional substrates, such as soil and gravel have low capacity for nitrogen and phosphorus removal. This study aims to enhance nutrients removal in constructed wetland systems by using series of substrates including calcium silicate hydrate (CSH), vermiculite and ceramsite which are all investigated individually in static experiment or mixed in batch and continuous flow experiments. The result showed that the efficiency of phosphorus removal by CSH could reach 97%, much higher than the other substrates. However, when it was applied in CW, the removal efficiency decreased. Although vermiculite showed the highest ammonia nitrogen removal efficiency of 65.91%, the ammonia nitrogen removal efficiency may have depended on the action of microorganism. High total nitrogen removal efficiency was obtained in continuous-flow mixed substrate CW. Under a hydraulic retention time (HRT) of 18h and hydraulic loading rate (HLR) of 0.496 m(3)/m(3).d, average total nitrogen removal efficiency of above 91% was achieved, but the average phosphorus removal efficiency was around 65% and this needs to be improved further.

  19. Electrochemical characterization of Geobacter lovleyi identifies limitations of microbial fuel cell performance in constructed wetlands.

    PubMed

    Corbella, Clara; Steidl, Rebecca P; Puigagut, Jaume; Reguera, Gemma

    2017-06-01

    Power generation in microbial fuel cells implemented in constructed wetlands (CW-MFCs) is low despite the enrichment of anode electricigens most closely related to Geobacter lovleyi. Using the model representative G. lovleyi strain SZ, we show that acetate, but not formate or lactate, can be oxidized efficiently but growth is limited by the high sensitivity of the bacterium to oxygen. Acetate and highly reducing conditions also supported the growth of anode biofilms but only at optimal anode potentials (450 mV vs. standard hydrogen electrode). Still, electrode coverage was poor and current densities, low, consistent with the lack of key c-type cytochromes. The results suggest that the low oxygen tolerance of G. lovleyi and inability to efficiently colonize and form electroactive biofilms on the electrodes while oxidizing the range of electron donors available in constructed wetlands limits MFC performance. The implications of these findings for the optimization of CW-MFCs are discussed. [Int Microbiol 20(2):55-64 (2017)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  20. Maximizing pollutant removal in constructed wetlands: should we pay more attention to macrophyte species selection?

    PubMed

    Brisson, J; Chazarenc, F

    2009-06-15

    While the positive role of macrophytes on removal efficiency in constructed wetlands has been well established, possible differences in performance between plants species of comparable life forms and sizes are much harder to demonstrate. We reviewed 35 experimental studies published in peer-reviewed journals and proceedings on the effect of macrophyte species selection on pollutant removal in SSFCW. The studies cover a wide range of macrophyte species, experimental approaches (from well-replicated microcosm experiments to comparison between full full-size constructed wetlands), climatic conditions (from tropical to cold-temperate) and types of effluent (domestic, industrial, etc.). Frequent methodological limitations in these studies compel caution in the interpretation of their results. Yet, the fact that the majority found some (occasionally large) differences in efficiency between plant species for one or more type of pollutant suggests that macrophyte species selection does matter. However, there is little generalization to be made that could help guide species selection for SSFCW, except for the exact conditions in which the experiments were done. For example, the same pair of species that was tested in different studies occasionally gave opposite results in terms of which one performs best. Also, most studies provided few insights on the mechanisms or plant properties that could explain the observed differences in plant species efficiency. Finally, we discuss other relevant research questions and approaches that could help better guide macrophyte species selection for CW.

  1. Occurrence and removal of estrogens, progesterone and testosterone in three constructed wetlands treating municipal sewage in the Czech Republic.

    PubMed

    Vymazal, Jan; Březinová, Tereza; Koželuh, Milan

    2015-12-01

    Estrogenic hormones, progesterone and testosterone are endocrine-disrupting chemicals and their presence in aquatic environments represents a potentially adverse environmental and public health impact. There is a considerable amount of information about removal of estrogens, progesterone and testosterone in conventional wastewater treatment plants, namely activated sludge systems. However, the information about removal of these compounds in constructed wetlands is very limited. Three constructed wetlands with horizontal subsurface flow in the Czech Republic have been selected to evaluate removal of estrogens (estrone, estriol, 17β-estradiol, 17α-ethinylestradiol), testosterone and progesterone. Monitored constructed wetlands for 100, 150 and 200 PE have been in operation for more than 10 years and all systems exhibit very high treatment efficiency for organics and suspended solids. The results indicate that removal of all estrogens, progesterone and testosterone was high and only estrone was found in the outflow from one constructed wetland in concentrations above the limit of quantification 1 ng l(-1). The limits of quantification for other estrogens, i.e., 10 ng l(-1) for estriol, 1 ng l(-1) for 17β-estradiol and 2 ng l(-1) for 17α-ethinylestradiol were not exceeded in the outflow of all monitored constructed wetlands. Also, for progesterone and testosterone, all outflow concentrations were below the LOQ of 0.5 ng l(-1). The results indicated that constructed wetlands with horizontal subsurface flow are a promising technology for elimination of estrogens, progesterone and testosterone from municipal sewage but more information is needed to confirm this finding. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Constructed wetlands for wastewater and activated sludge treatment in north Greece: a review.

    PubMed

    Tsihrintzis, V A; Gikas, G D

    2010-01-01

    Constructed wetlands used for the treatment of urban, industrial and agricultural wastewater have become very popular treatment systems all over the world. In Greece, these systems are not very common, although the climate is favourable for their use. During recent years, there have been several attempts for the implementation of these systems in Greece, which include, among others, pilot-scale systems used for research, and full-scale systems designed and/or constructed to serve settlements or families. The purpose of this paper is the presentation of systems operating in Northern Greece, which have been studied by the Laboratory of Ecological Engineering and Technology of Democritus University of Thrace and others. A comparison is made of different system types, and the effect of various design and operational parameters is presented. Current research shows the good and continuous performance of these systems.

  3. Emergent macrophytes select for nitrifying and denitrifying microorganisms in constructed wetlands

    NASA Astrophysics Data System (ADS)

    Trias, Rosalia; Ramió Pujol, Sara; Bañeras, Lluis

    2014-05-01

    The use of constructed wetlands for wastewater treatment is a reliable low-cost alternative that has been widely developed during the last years. Several processes involving plants, sediments, and microbial communities contribute to nitrogen removal in wetlands. Vegetation plays an important role in this process, not only by nutrient assimilation but also by the stimulation of the plant associated microbiota. Plants supply oxygen at the close proximity of the root surface that may favour ammonia oxidizers. At the same time, exudation of organic compounds potentially speeds-up denitrification in the anoxic environment. The aim of this work was to understand the plant-microbe interactions at the root level in the Empuriabrava free water surface constructed wetland (Spain). The roots of the macrophytes Typha latifolia, Typha angustifolia, Phragmites australis and Bolboschoenus maritimus were sampled at four dates from January to September 2012, covering all the stages of plant growth. Additionally, sediment surrounding vegetation and non-vegetated sediments were sampled. Microbial community structure was analysed by pyrosequencing of bacterial and archaeal 16S rDNA and functional genes (nirK, nirS, nosZ and amoA). Bacterial communities were significantly different in sediments of the vegetated areas compared to the root surface. Plant roots exhibited a higher proportion of proteobacteria whereas Actinobacteria were dominant in sediments. The nitrifiers Nitrosomonas sp. and Nitrosococcus sp. accounted for less than 1% of all sequences. Archaeal communities were dominated by the Miscellaneous Crenarchaeotic Groups C2 and C3 and Methanomicrobia. Higher relative abundances of MCG were found in roots of P. australis, B. maritimus and T. angustifolia. Ammonia oxidizing archaea accounted for less than 0.1% of all sequences but were consistently more abundant in sediment samples compared to roots. NirK and NirS-type bacterial communities showed clearly distinct distribution

  4. Using a constructed wetland for non-point source pollution control and river water quality purification: a case study in Taiwan.

    PubMed

    Wu, C Y; Kao, C M; Lin, C E; Chen, C W; Lai, Y C

    2010-01-01

    The Kaoping River Rail Bridge Constructed Wetland, which was commissioned in 2004, is one of the largest constructed wetlands in Taiwan. This multi-function wetland has been designed for the purposes of non-point source (NPS) pollutant removal, wastewater treatment, wildlife habitat, recreation, and education. The major influents of this wetland came from the local drainage trench containing domestic, agricultural, and industrial wastewaters, and effluents from the wastewater treatment plant of a paper mill. Based on the quarterly investigation results from 2007 to 2009, more than 96% of total coliforms (TC), 48% of biochemical oxygen demand (BOD), and 40% of nutrients (e.g. total nitrogen, total phosphorus) were removed via the constructed wetland system. Thus, the wetland system has a significant effect on water quality improvement and is capable of removing most of the pollutants from the local drainage system before they are discharged into the downgradient water body. Other accomplishments of this constructed wetland system include the following: providing more green areas along the riversides, offering more water assessable eco-ponds and eco-gardens for the public, and rehabilitating the natural ecosystem. The Kaoping River Rail Bridge Constructed Wetland has become one of the most successful multi-function constructed wetlands in Taiwan. The experience obtained from this study will be helpful in designing similar natural treatment systems for river water quality improvement and wastewater treatment.

  5. Evaluation of an alternative method for wastewater treatment containing pesticides using solar photocatalytic oxidation and constructed wetlands.

    PubMed

    Berberidou, Chrysanthi; Kitsiou, Vasiliki; Lambropoulou, Dimitra A; Antoniadis, Αpostolos; Ntonou, Eleftheria; Zalidis, George C; Poulios, Ioannis

    2017-06-15

    The present study proposes an integrated system based on the synergetic action of solar photocatalytic oxidation with surface flow constructed wetlands for the purification of wastewater contaminated with pesticides. Experiments were conducted at pilot scale using simulated wastewater containing the herbicide clopyralid. Three photocatalytic methods under solar light were investigated: the photo-Fenton and the ferrioxalate reagent as well as the combination of photo-Fenton with TiO2 P25, which all led to similar mineralization rates. The subsequent treatment in constructed wetlands resulted in further decrease of DOC and inorganic ions concentrations, especially of NO3(-). Clopyralid was absent in the outlet of the wetlands, while the concentration of the detected intermediates was remarkably low. These findings are in good agreement with the results of phytotoxicity of the wastewater, after treatment with the ferrioxalate/wetlands process, which was significantly reduced. Thus, this integrated system based on solar photocatalysis and constructed wetlands has the potential to effectively detoxify wastewater containing pesticides, producing a purified effluent which could be exploited for reuse applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Suitability of macrophytes for nutrient removal from surface flow constructed wetlands receiving secondary treated sewage effluent in Queensland, Australia.

    PubMed

    Greenway, M

    2003-01-01

    From a botanical perspective the major difference between waste stabilisation ponds and wetlands is the dominance of algae or floating plants in the former and emergent plants in the latter. Algae, floating and submerged plants remove nutrients directly from the water column whereas emergent species remove nutrients from the sediment. Water depth is a crucial factor in determining which plant types will become established. Surface flow constructed wetlands offer the greatest potential to grow a wide variety of different types of macrophytes. In assessing the suitability of plant species for nutrient removal, consideration must be given not only to nutrient uptake for growth but also storage of nutrients as plant biomass. A survey of macrophytes in 15 surface flow constructed wetlands treating secondary effluent was conducted in Queensland; 63 native species and 14 introduced species were found. Emergent species have been able to tolerate deeper water than in their natural environment and permanent waterlogging. All species grew well in the higher nutrient enriched wastewater. Submerged, floating leaved-attached and free floating species had the highest tissue nutrient content, followed by aquatic creepers. All these species remove nutrients from the water column. Emergent species had lower nutrient content but a greater biomass and were therefore able to store more nutrients per unit area of wetland. In order to maximise the efficiency of constructed wetlands for nutrient removal, a range of species should be used. Native species should be selected in preference to introduced/exotic species.

  7. Metal and metalloid removal in constructed wetlands, with emphasis on the importance of plants and standardized measurements: A review.

    PubMed

    Marchand, L; Mench, M; Jacob, D L; Otte, M L

    2010-12-01

    This review integrates knowledge on the removal of metals and metalloids from contaminated waters in constructed wetlands and offers insight into future R&D priorities. Metal removal processes in wetlands are described. Based on 21 papers, the roles and impacts on efficiency of plants in constructed wetlands are discussed. The effects of plant ecotypes and class (monocots, dicots) and of system size on metal removal are addressed. Metal removal rates in wetlands depend on the type of element (Hg > Mn > Fe = Cd > Pb = Cr > Zn = Cu > Al > Ni > As), their ionic forms, substrate conditions, season, and plant species. Standardized procedures and data are lacking for efficiently comparing properties of plants and substrates. We propose a new index, the relative treatment efficiency index (RTEI), to quantify treatment impacts on metal removal in constructed wetlands. Further research is needed on key components, such as effects of differences in plant ecotypes and microbial communities, in order to enhance metal removal efficiency. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. The role of constructed wetlands in sequestering eroded carbon in an agricultural landscape.

    NASA Astrophysics Data System (ADS)

    Maynard, J. J.; O'Geen, A. T.; Dahlgren, R. A.

    2008-12-01

    The fate of carbon lost by erosion is not well understood in agricultural settings. Recent models suggest that wetlands and other small water bodies may serve as important long-term sinks of eroded carbon. An estimated 2.6 million small (less than 104 m2), artificial water bodies (e.g. water catchment reservoirs, farm ponds, and wetlands) are scattered across the United States. These areas are estimated to receive one third of all eroded materials. Consequently, carbon accumulation in small subaqueous environments may have a significant effect on carbon storage. The conversion of marginal farmland to constructed and restored wetlands is a growing land use in California's Central Valley. Many of these systems receive agricultural runoff as their main water supply, which is rich in suspended sediment and nutrients. This study examined the potential for carbon sequestration in an eight-year-old seasonally saturated constructed wetland that receives tailwater from over 4,000 acres of farmland. The temporal and spatial dynamics of carbon and sediment accumulation were evaluated by employing a spatially explicit sampling design to measure net sedimentation and net above-ground biomass in 2004 and 2005. Additionally, in 2006, sediment cores were collected to the antecedent (time zero) soil layer, which ranged between 2 and 50 cm below the surface. The spatial variability of carbon and sediment accumulation was modeled with geostatistics. Average sediment accumulation rate, nearly doubled from 2004 to 2005, with rates of 5.8 kg m-2 y-1 (range: 0-80 kg m-2 y-1) in 2004 and 11.9 kg m-2 y-1 (range: 0-93 kg m2 y-1) in 2005. Average carbon accumulation rate did not change between years, with rates of 0.290 kg m-2 y-1 in 2004 and 0.294 kg m-2 y-1 in 2005, indicating a change in carbon source between years. Average total carbon content of soils in the contributing watershed is 8 g kg-1, whereas average carbon content of inflowing sediment was 14 g kg-1, resulting in an enrichment

  9. Effect of N:P ratio of influent on biomass, nutrient allocation, and recovery of Typha latifolia and Canna 'Bengal Tiger' in a laboratory-scale constructed wetland

    USDA-ARS?s Scientific Manuscript database

    Constructed wetlands (CWs) are an effective low-technology approach for treating agricultural, industrial, and municipal wastewater. Recovery of phosphorous by constructed wetland plants may be affected by wastewater nitrogen to phosphorous (N:P) ratios. Varying N:P ratios were supplied to Canna '...

  10. Comparisons of mosquito populations before and after construction of a wetland for water quality improvement in Pitt County, North Carolina, and data-reliant vectorborne disease management.

    PubMed

    Anderson, Alice L; O'Brien, Kevin; Hartwell, Megan

    2007-04-01

    Wetlands serve an important purpose in flood control and water quality, but constructed-wetland sites also provide habitats for mosquito breeding. Communities near constructed-wetland sites often raise a "mosquito" objection when constructed wetlands are proposed. Wildlife and wetland advocates can confuse the public by making unsubstantiated claims about natural predators eliminating or controlling mosquito problems in a constructed wetland. Management of constructed-wetland mosquito habitat, with adequate mosquito surveillance and data analysis, can help lead to a successful project and satisfied citizens. The cooperative project described in this paper, was conducted in the town of Simpson, North Carolina, and was designed to determine the mosquito population impact of wetland construction at Mill Branch Stream, a small tributary of the Tar River in Eastern North Carolina. In the authors' analysis of three years of mosquito surveillance data, month (time of year standing in for temperature and day length) was a significant factor in regression analysis for mosquito numbers, but rainfall was not. Numbers of mosquitoes were not found to be significantly higher after construction than before construction.

  11. Efficacy of constructed wetlands in pesticide removal from tailwaters in the Central Valley, California.

    PubMed

    Budd, Robert; O'Geen, Anthony; Goh, Kean S; Bondarenko, Svetlana; Gan, Jay

    2009-04-15

    Pollutants in agricultural irrigation return flow (tailwater) constitute a significant nonpoint source of pollution in intensive agricultural regions such as the Central Valley of California. Constructed wetlands (CWs) represent a feasible mitigation option to remove pollutants including pesticides in the tailwater. In this study, we evaluated two CWs in the Central Valley for their performance in removing pyrethroid and organophosphate insecticides under field-scale production conditions. Both CWs were found to be highly effective in reducing pyrethroid concentrations in the tailwater, with season-average concentration reductions ranging from 52 to 94%. The wetlands also reduced the flow volume by 68-87%, through percolation and evapotranspiration. When both concentration and volume reductions were considered, the season-average removal of pyrethroids ranged from 95 to 100%. The primary mechanism for pyrethroid removal was through sedimentation of pesticide-laden particles, which was influenced by hydraulic residence time and vegetation density. Temporal analysis indicates a potential efficiency threshold during high flow periods. The season-average removal of chlorpyrifos ranged 52-61%. The wetlands, however, were less effective at removing diazinon, likely due to its limited sorption to sediment particles. Analysis of pesticide partitioning showed that pyrethroids were enriched on suspended particles in the tailwater. Monitoring of pesticide association with suspended solids and bed sediments suggested an increased affinity of pyrethroids for lighter particles with the potential to move further downstream before subject to sedimentation. Results from this study show that flow-through CWs, when properly designed, are an effective practice for mitigating hydrophobic pesticides in the irrigation tailwater.

  12. [Comparison of nutrient removal ability between Cyperus alternifolius and Vetiveria zizanioides in constructed wetlands].

    PubMed

    Liao, Xindi; Luo, Shiming; Wu, Yinbao; Wang, Zhisan

    2005-01-01

    In order to compare the nutrient removal ability of Cyperus alternifolius and Vetiveria zizanioides, a 17.0 m2 subsurface flow wetland covered with Cyperus alternifolius and another 13.3 m2 one covered with Vetiveria zizanioides were constructed for piggery wastewater treatment, and the biomass as well as the N, P, Cu and Zn contents in the root and shoot of the plants was measured by the end of each season. The results showed that the below-ground biomass of V. zizanioides was greater than that of C. alternifolius. By the contrary, the above-ground biomass of C. alternifolius was greater than that of V. zizanioides. The annual biomass yield of C. alternifolius was 2.3 times higher than that of V. zizanioides,which was 3406.47 g x m(-2) and 1483.88 g x m(-2), respectively. The N concentration in C. alternifolius tissue was higher than that in V. zizanioides tissue, being 22.69 mg x g(-1) and 15.44 mg x g(-1) respectively, and similarly, the P concentration in C. alternifolius tissue was higher than that in V. zizanioides tissue, being 6.09 mg x g(-1) and 5.47 mg x g(-1) respectively. The Cu and Zn concentrations in C. alternifolius tissue were a little higher than those in V. zizanioides. 68.72 g N x m(-2) and 18.49 g P x m(-2) were removed by harvesting C. alternifolius vegetation, while 8.93 g N x m(-2) and 3.69 g x P m(-2) were removed by harvesting V. zizanioides vegetation. It was concluded that the removals of N, P, Cu and Zn by harvesting vegetation were 4-7 times higher in C. alternifolius wetland than in V. zizanioides wetland.

  13. Use of submitochondrial particle (SMP) assays for assessing wetlands constructed for sequestering acid mine runoff

    SciTech Connect

    Bettermann, A.D.; Haahr, J.E.; Lazorchak, J.M.

    1995-12-31

    Use of constructed wetlands to sequester metals from acid mine drainage is part of a USEPA SITE demonstration at Burleigh Tunnel near Silverplume, Colorado. Samples are collected on a seasonal basis for toxicity evaluation of two different pilot treatment systems. Water samples were obtained from the outflow of two experimental wetland cells utilizing either upflow and downflow treatment, as well as upstream and downstream of the discharge of Burleigh Tunnel to Clear Creek. Submitochondrial Particle (SMP), Ceriodaphnia dubia and Pimephales promelas acute bioassays were used to evaluate the water quality. The SMP bioassay is based on the electron transfer complex derived from mitochondria. Toxic responses result from subcellular perturbations of various subsets of enzyme systems contained in the complex. In prior work, a 0.79 r{sup 2} was reported between the SMP bioassay and P. promelas for 11 inorganics on the EPA Priority Pollutant list. The SMP bioassay provided data consistent with the whole organism results. The two most toxic samples: the Burleigh outflow, and the Clear Creek Upstream sample, gave C. dubia LC50s of 1.01% and 8.41%, respectively. The Burleigh outflow P. promelas LC50 was 1.55%. SMP EC50s for the Burleigh outflow and the Clear Creek Upstream sample were 0.63% and 1.63%, respectively. As the SMP bioassay requires 1 hour to run and costs approximately 1/10th of whole organism assays, it was feasible to determine EC50 values for 7 samples vs. the two sample LC50s determined using whole organism assays. The SMP bioassays can provide sufficient sampling density, at low cost, allowing effective delineation of wetland performance over time.

  14. Studies on sustainability of simulated constructed wetland system for treatment of urban waste: Design and operation.

    PubMed

    Upadhyay, A K; Bankoti, N S; Rai, U N

    2016-03-15

    New system configurations and wide range of treatability make constructed wetland (CW) as an eco-sustainable on-site approach of waste management. Keeping this view into consideration, a novel configured three-stage simulated CW was designed to study its performance efficiency and relative importance of plants and substrate in purification processes. Two species of submerged plant i.e., Potamogeton crispus and Hydrilla verticillata were selected for this study. After 6 months of establishment, operation and maintenance of simulated wetland, enhanced reduction in physicochemical parameters was observed, which was maximum in the planted CW. The percentage removal (%) of the pollutants in three-stage mesocosms was; conductivity (60.42%), TDS (67.27%), TSS (86.10%), BOD (87.81%), NO3-N (81.28%) and PO4-P (83.54%) at 72 h of retention time. Submerged macrophyte used in simulated wetlands showed a significant time dependent accumulation of toxic metals (p ≤ 0.05). P. crispus accumulated the highest Mn (86.36 μg g(-1) dw) in its tissue followed by Cr (54.16 μg g(-1) dw), Pb (31.56 μg g(-1) dw), Zn (28.06 μg g(-1) dw) and Cu (25.76 μg g(-1) dw), respectively. In the case of H. verticillata, it was Zn (45.29), Mn (42.64), Pb (22.62), Cu (18.09) and Cr (16.31 μg g(-1) dw). Thus, results suggest that the application of simulated CW tackles the water pollution problem more efficiently and could be exploited in small community level as alternative and cost effective tools of phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Effects of effluent recirculation in vertical-flow constructed wetland on treatment efficiency of livestock wastewater.

    PubMed

    Lian-sheng, He; Hong-liang, Liu; Bei-dou, Xi; Ying-bo, Zhu

    2006-01-01

    Enhancing the treatment efficiency of livestock wastewater by effluent recirculation is investigated in a pilot-scale vertical-flow constructed wetland. The wetland system is composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and common reed Phragmites typhia are planted, respectively; each stage has a dimension of 4 m(2) (2 m x 2 m). Wastewater from the facultative pond is fed into the system intermittently at a flow rate of 0.4 m(3)/d. Recirculation rates of 0, 25%, 50%0, 100% and 150% are adopted to evaluate the effect of the recirculation rate on pollutants removal. This shows that with effluent recirculation the average removal efficiencies of NH4-N, BOD5 and SS obviously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%o, 50.2%, and 49.3% without effluent recirculation. But the improvement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N, DO and oxidation-reduction potential (ORP) of inflow and outflow reveal that the adoption of effluent recirculation is beneficial to the formation of oxide environment in wetland. The exponential relationships with excellent correlation coefficients (R(2) > 0.93) are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of the outflow decreases as the alkalinity is consumed by the gradually enhanced nitrification process. When recirculation rate is kept constant at 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.

  16. Sulphur transformation and deposition in the rhizosphere of Juncus effusus in a laboratory-scale constructed wetland.

    PubMed

    Wiessner, A; Kuschk, P; Jechorek, M; Seidel, H; Kästner, M

    2008-09-01

    Sulphur cycling and its correlation to removal processes under dynamic redox conditions in the rhizosphere of helophytes in treatment wetlands are poorly understood. Therefore, long-term experiments were performed in laboratory-scale constructed wetlands treating artificial domestic wastewater in order to investigate the dynamics of sulphur compounds, the responses of plants and nitrifying microorganisms under carbon surplus conditions, and the generation of methane. For carbon surplus conditions (carbon:sulphate of 2.8:1) sulphate reduction happened but was repressed, in contrast to unplanted filters mentioned in literature. Doubling the carbon load caused stable and efficient sulphate reduction, rising of pH, increasing enrichment of S(2-) and S(0) in pore water, and finally plant death and inhibition of nitrification by sulphide toxicity. The data show a clear correlation of the occurrence of reduced S-species with decreasing C and N removal performance and plant viability in the experimental constructed wetlands.

  17. [Treatment of marine-aquaculture effluent by the multi-soil-layer (MSL) system and subsurface flow constructed wetland].

    PubMed

    Song, Ying; Huang, Yu-ting; Ge, Chuan; Zhang, Hao; Chen, Xin; Zhang, Zhi-jianz; Luo, An-cheng

    2014-09-01

    To evaluate the feasibility of using multi-soil-layer (MSL) system and subsurface flow constructed wetland to treat the wastewater of marine cultured Penaeus vannamei and to determine the suitable process for the local aquaculture wastewater pollution characteristics. In this study, MSL system and four constructed wetland systems with Spartina anglica, Phragmites australis, Typha latifolia and unplanted system were evaluated for their potentials of pollutants removal capacity. The results showed the average removal rates of chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH(4)+ -N) and nitrate (NO-(3) -N) by MSL system were 80. 38% ± 2. 14% , 68. 14% ± 3.51% , 40.79% ± 3. 10% , 42. 68% ± 2.90% and 54. 19% ± 5. 15% , respectively. Additionally, the ability of pollutants removal of other four wetland systems decreased in the order: Spartina anglica, Phragmites australis, Typha latifolia and unplanted system.

  18. A practical method for the restoration of clogged rural vertical subsurface flow constructed wetlands for domestic wastewater treatment using earthworm.

    PubMed

    Li, Huaizheng Z; Wang, Sheng; Ye, Jianfeng F; Xu, Zuxin X; Jin, Wei

    2011-01-01

    This paper presents a simple method for the restoration of clogged vertical subsurface flow constructed wetland by earthworm. Since clogging always takes place at the top layer, epigeic earthworm is suitable for restoration of the clogged wetland. Earthworm can not only loosen the substrate, but also transform 80∼90% of undissolved organic particles into dissolved matters. Accordingly, the accumulated solids in substrate with earthworm are 50% less than the one without earthworm. The wetland with earthworm removed 2∼5 percentage points more nitrogen and 12 percentage points more phosphorous for its better ventilation conditions, while 2 percentage points less COD because the generation of dissolved organic matter from undissolved organic particles by earthworm. In general, the influence of earthworm on the effluent quality of the wetland could be ignored. Hydrology of six full-scale clogged wetlands was restored by Eisenia foetida. The optimal strength of earthworm addition is 0.5 kg/m2, which spend RMB six yuan/m2, less than € 0.75/m2. No specific training is required for the staffs on this method; it takes 10 days to restore the clogged wetland.

  19. Removal of fluoride and arsenic by pilot vertical-flow constructed wetlands using soil and coal cinder as substrate.

    PubMed

    Li, Juan; Liu, Xinchun; Yu, Zhisheng; Yi, Xin; Ju, Yiwen; Huang, Jing; Liu, Ruyin

    2014-01-01

    This study evaluated the performance of soil and coal cinder used as substrate in vertical-flow constructed wetlands for removal of fluoride and arsenic. Two duplicate pilot-scale artificial wetlands were set up, planted respectively with cannas, calamus and no plant as blank, fed with a synthetic sewage solution. Laboratory (batch) incubation experiments were also carried out separately to ascertain the fluoride and arsenic adsorption capacity of the two materials (i.e. soil and coal cinder). The results showed that both soil and coal cinder had quite high fluoride and arsenic adsorption capacity. The wetlands were operated for two months. The concentrations of fluoride and arsenic in the effluent of the blank wetlands were obviously higher than in the other wetlands planted with cannas and calamus. Fluoride and arsenic accumulation in the wetlands body at the end of the operation period was in range of 14.07-37.24% and 32.43-90.04%, respectively, as compared with the unused media.

  20. Effects of a constructed wetland and pond system upon shallow groundwater quality.

    PubMed

    Ouyang, Ying

    2013-05-01

    Constructed wetland (CW) and constructed pond (CP) are commonly utilized for removal of excess nutrients and certain pollutants from stormwater. This study characterized shallow groundwater quality for pre- and post-CW and CP system conditions using data from monitoring wells. Results showed that the average concentrations of groundwater phosphorus (P) decreased from pre-CW to post-CW but increased from pre-CP to post-CP. The average concentrations of groundwater total Kjeldahl nitrogen and ammonium (NH(4)(+)) increased from pre-CW (or CP) to post-CW (or CP), whereas the average concentrations of groundwater arsenic (As), chromium, nickel, and zinc (Zn) decreased from pre-CW to post-CW regardless of the well locations. Variations of groundwater cadmium, copper, and Zn concentrations were larger in pre-CP than in post-CP and had a tendency to decrease from pre-CP to post-CP. In general, the average concentrations of groundwater aluminum and manganese decreased and of groundwater calcium, iron, magnesium, and sodium increased from pre-CP to post-CP. The average values of water levels (depth from the ground surface), redox potential, and conductance decreased and of chloride and sulfate (SO(4)(-2)) increased after the wetland and pond were constructed regardless of the well locations. Results further revealed that there were significant differences (α = 0.05) between the pre- and post-CW (or CP) for redox potential, water level, and As. This study suggests that the CW-CP system had discernible effects on some of the shallow groundwater quality constituents. This information is very useful for fully estimating overall performance of stormwater treatment with the CW-CP system.