Science.gov

Sample records for constructed wetland treating

  1. 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. PMID:25837565

  2. Performance of constructed wetland treating wastewater from seafood industry.

    PubMed

    Yirong, C; Puetpaiboon, U

    2004-01-01

    Wastewater from seafood industry contains high concentrations of organic matter, nitrogen compounds, and solid matter. Constructed wetland can be used as tertiary treatment and for nutrient recycling. This research studied the performance of nitrogen and suspended solids removal efficiency of a constructed wetland treating wastewater from a seafood-processing factory located at Songkhla, southern Thailand. The existing constructed wetland has dimensions of 85 m, 352 m and 1.5 m in width, length and depth respectively, with an area of about 29,920 m2. The water depth of 0.30 m is maintained in operation with plantation of cattails (Typha augustifolia). Flow rate of influent ranged between 500-4,660 m3/d. Average hydraulic retention time in the constructed wetland was about 4.8 days. Influent and effluent from the constructed wetland were collected once a week and analyzed for pH, temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD5), Suspended solid (SS), total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3-N), organic nitrogen (Org-N), nitrate (NO3-N), and nitrite (NO2-N). The average removal efficiencies of BOD5, SS, TKN, NH3-N, and Org-N were 84%, 94%, 49%, 52% and 82%, respectively. It was found that the constructed wetland acting as a tertiary treatment process provided additional removal of BOD5, SS and TKN from wastewater from the seafood industry.

  3. Particle retention in compact constructed wetlands treating highway stormwater.

    PubMed

    Chen, Yaoping; Park, Kisoo; Kim, Youngchul

    2014-01-01

    Three pilot-scale compact constructed wetland systems were constructed to treat stormwater from a highway. They each comprised a sedimentation tank, and a vertical flow (VF) wetland bed equipped with a recirculation device. The VF wetland beds were filled with woodchip, pumice and volcanic gravel, respectively. According to the analysis of the particle size distributions (0.52-500 μm), the predominant particles in stormwater ranged in size from 0.52-30 μm. In the sedimentation tank, with a 24 h settling time, the settling efficiencies of the particles increased with increasing particle size. In the VF wetland beds, further capture of the particles was achieved; however, the woodchip and volcanic gravel wetlands displayed relatively low trapping of micro-particles, due to the natural properties of the substrates. Recirculation caused a positive effect on the retention of particles in the woodchip wetland. Due to the employment of a pre-treatment tank and the high porosity of materials, the accumulated solids occupied very low proportions of the pore volume in the wetland substrates. The results also showed that the accumulation of copper, zinc and lead do not pose a problem for the disposal of the substrates when the wetlands reach the end of their operational lifetime. PMID:24718334

  4. Treating swine wastewater by integrating earthworms into constructed wetlands.

    PubMed

    Nuengjamnong, Chackrit; Chiarawatchai, Nathasith; Polprasert, Chongrak; Otterpohl, Ralf

    2011-01-01

    The aim of this study was to investigate the application of integrating earthworms (Pheretima peguana) into two-stage pilot-scale subsurface-flow constructed wetlands (SFCWs) receiving swine wastewater in terms of their treatment performance, namely organic content, total kjeldahl nitrogen (TKN), and solid reduction as well as the quantity of sludge production. There was a minor difference in terms of removal efficiency according to each parameter when comparing the unit with earthworms to the one without earthworms. Both achieved the TKN, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total volatile suspended solids (TVSS), suspended solids (SS), and total solids (TS) removal by more than 90 %. The earthworms helped in reducing the sludge production on the surface of constructed wetlands 40 % by volume, which resulted in lowering operational costs required to empty and treat the sludge. The plant biomass production was higher in the wetlands without earthworms. Further research could be undertaken in order to effectively apply earthworms inside the wetlands.

  5. 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

  6. Constructed wetlands for treating acid drainage at TVA Facilities: Progress report

    SciTech Connect

    Tomljanovich, D.A.; Brodie, G.A.; Hammer, D.A.

    1988-03-01

    A comprehensive overview is presented of TVA's use of constructed wetlands to naturally treat water quality problems associated with acid drainage at its fossil plants and the inactive Fabius Coal Mine and Preparation Plant in Jackson County, Alabama. TVA constructed its first wetland in May 1985. As of December 1987, a total of eight constructed wetlands, one enhanced natural wetland receiving acid drainage, and one former chemical treatment pond were being monitored as treatment wetlands. Some measure of success is being achieved at all the wetland systems. However, to achieve compliance quality effluent (total Fe <3.0 mg/L, total Mn <2.0 mg/L, pH 6.0--9.0 s.u., and total suspended solids <32.0 mg/L) interim chemical treatment is being used at COF to treat manganese, and at WCF to treat low pH. At KIF, water is being pumped from the final cell of the wetland to the active ashpond as an interim measure until it is shown to consistently yield compliance quality effluent. Chemical treatment is also being used to augment wetlands treatment at the Fabius Impoundment 2 and Impoundment 4 wetlands. Where chemical treatment is required, reduced chemical costs result from some level of wetlands treatment. Successful wetlands treatment has been demonstrated at three sites, where no chemical treatment is required. In the remaining two newly constructed wetlands, insufficient data exist to assess their treatment capability. Overall average construction cost based on nine wetlands was $1.13/ft/sup 2/ ($49,223/ac). Before converting one chemical treatment pond (Fabius Impoundment 3) to a wetland, TVA was annually spending $12,000 to $15,000 for chemicals and $10,000 for pond maintenance that failed to maintain complying discharges. Complying discharges and an annual wetland maintenance cost of about $1000 make the wetland an attractive and cost-beneficial treatment method. 2 refs., 15 figs., 10 tabs.

  7. Vegetation changes and partitioning of selenium in 4-year-old constructed wetlands treating agricultural drainage.

    PubMed

    Lin, Z Q; Terry, N; Gao, S; Mohamed, S; Ye, Z H

    2010-03-01

    The knowledge of selenium (Se) partitioning in treatment wetlands and wetland vegetation management are essential for long-term effective operation of constructed wetlands treating Se-laden agricultural tile-drainage in central California. In this field study, samples from different compartments of treatment wetlands were collected and the vegetation change in each wetland cell was examined four years after the wetland's inception. The results showed that saltgrass (Distichlis spicata) and rabbitfoot grass (Polypogon monspeliensis) were less competitive than cattail (Typha latifolia) and saltmarsh bulrush (Scirpus robustus). Over 90% of the wetland cell originally vegetated with saltgrass or rabbitfoot grass was occupied by invasive plants--i.e., when invasive species were not controlled in the wetlands. More Se was likely found in sediments from vegetated regions, compared to the unvegetated areas of the wetland cell. Particularly, rhizosphere sediments accumulated about 4-fold more Se than non-rhizosphere sediments. Among the total Se retained in the wetland 90% of the total Se was partitioned in the top 10-cm layer of sediment. The Se accumulation in plant materials accounted for about 2% of the total Se mass retained in each wetland cell. This field study demonstrated that wetland plants play significant roles in the treatment of Se-laden agricultural drainage.

  8. [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.

  9. Effect of polyaluminium chloride on phosphorus removal in constructed wetlands treated with swine wastewater.

    PubMed

    Reddy, G B; Forbes, Dean A; Hunt, P G; Cyrus, Johnsely S

    2011-01-01

    Total phosphorus (TP) removal in aged constructed wetlands poses a challenge, especially when treated with swine wastewater with high concentrations of phosphorus (P). Our earlier studies with anaerobic lagoon swine wastewater treatment in constructed wetlands showed a decline in P removal (45-22%) with increased years of operation. These particular wetlands have been treated with swine wastewater every year since the first application in 1997. Preliminary lab-scale studies were conducted to evaluate the efficiency of polyaluminium chloride (PAC) in the removal of phosphate-P (PO4-P) from swine wastewater. The experimental objective was to increase the phosphorus treatment efficiency in constructed wetland by adding PAC as a precipitating agent. PAC was added by continuous injection to each wetland system at a rate of 3 L day(-1) (1:5 dilution of concentrated PAC). Swine wastewater was added from an anaerobic lagoon to four constructed wetland cells (11m wide x 40m long) at TP loads of 5.4-6.1 kg ha(-1) day(-1) in two experimental periods, September to November of 2008 and 2009. Treatment efficiency of two wetland systems: marsh-pond-marsh (M-P-M) and continuous marsh (CM) was compared. The wetlands were planted with cattails (Typha latifolia L.) and bulrushes (Scirpus americanus). In 2008, PAC treatment showed an increase of 27.5 and 40.8% of TP removal over control in M-P-M and CM respectively. Similar trend was also observed in the following year. PAC as a flocculant and precipitating agent showed potential to enhance TP removal in constructed wetlands treated with swine wastewater. PMID:22049722

  10. Performance of Seasonally and Continuously Loaded Constructed Wetlands Treating Dairy Farm Wastewater.

    PubMed

    Wood, Jeffrey D; Gordon, Robert J; Madani, Ali; Stratton, Glenn W; Bromley, Heather M

    2015-11-01

    A 2-yr study compared the performance of seasonally and continuously loaded constructed wetlands treating dairy farm wastewater. One wetland was loaded during the growing season (GS) periods only, while the other was continuously loaded. Weekly samples were analyzed for 5-d biochemical oxygen demand (BOD), total suspended solids (TSS), total Kjeldahl N (TKN), total ammoniacal N (TAN), total P (TP), and . Annual average daily mass removal rates (kg ha) were similar for both wetlands in both years; however, seasonal differences were observed. With the exception of BOD in Year 2, average daily GS areal mass removal rates were higher for the seasonal wetland. However, GS mass exports from the seasonal wetland were higher by 28 to 94%, with the exception of BOD in Year 1. Annual mass reductions (MRs; %) for nutrients were higher for the continuous wetland in both years. Annual MRs were similar for in both years and for TSS in Year 2. Annual mass exports from the seasonal wetland were higher for nutrients and by 14 to 77% in both years. Pollutant MRs generally decreased during the nongrowing season (NGS) for the continuous wetland; however, in Year 2 when lower loading rates were used, the wetland still removed 84 to 99% of the pollutant masses. The continuous wetland also performed better during periods of high flow that occurred during the GS. Although there were minimal differences in annual treatment performance, continuously loaded systems require less additional infrastructure and should require less maintenance and may, therefore, be more attractive for agricultural applications. PMID:26641349

  11. Performance of Seasonally and Continuously Loaded Constructed Wetlands Treating Dairy Farm Wastewater.

    PubMed

    Wood, Jeffrey D; Gordon, Robert J; Madani, Ali; Stratton, Glenn W; Bromley, Heather M

    2015-11-01

    A 2-yr study compared the performance of seasonally and continuously loaded constructed wetlands treating dairy farm wastewater. One wetland was loaded during the growing season (GS) periods only, while the other was continuously loaded. Weekly samples were analyzed for 5-d biochemical oxygen demand (BOD), total suspended solids (TSS), total Kjeldahl N (TKN), total ammoniacal N (TAN), total P (TP), and . Annual average daily mass removal rates (kg ha) were similar for both wetlands in both years; however, seasonal differences were observed. With the exception of BOD in Year 2, average daily GS areal mass removal rates were higher for the seasonal wetland. However, GS mass exports from the seasonal wetland were higher by 28 to 94%, with the exception of BOD in Year 1. Annual mass reductions (MRs; %) for nutrients were higher for the continuous wetland in both years. Annual MRs were similar for in both years and for TSS in Year 2. Annual mass exports from the seasonal wetland were higher for nutrients and by 14 to 77% in both years. Pollutant MRs generally decreased during the nongrowing season (NGS) for the continuous wetland; however, in Year 2 when lower loading rates were used, the wetland still removed 84 to 99% of the pollutant masses. The continuous wetland also performed better during periods of high flow that occurred during the GS. Although there were minimal differences in annual treatment performance, continuously loaded systems require less additional infrastructure and should require less maintenance and may, therefore, be more attractive for agricultural applications.

  12. 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.

  13. Construction Simplicity and Cost as Selection Criteria Between Two Types of Constructed Wetlands Treating Highway Runoff

    NASA Astrophysics Data System (ADS)

    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 m2 each, while the two identical SSF covered 32 m2 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 m3/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 m3/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 (€14,676) was approximately 10% higher than that of the FWS (€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 €1799/year and €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 TAECCOD and TAECTSS values (€89.09/kg and €43.69/kg, respectively) compared to

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  15. Retention of manganese by a constructed wetland treating drainage from a coal ash disposal site

    SciTech Connect

    Kerrick, K.H.; Horner, M.

    1998-12-31

    A 3,200 m{sup 2} wetland was constructed in 1988 to treat drainage from an ash disposal site at a coal-fired electricity generating plant in western Pennsylvania. Concentrations of Fe and Mn in the drainage range from 30--80 mg/L and 10--20 mg/L, respectively. Acidity levels of 60--180 mg/L and a pH between 5--5.6 are typical. The wetland has always produced a high quality effluent with respect to Fe concentrations (usually less than 1 mg/L) and pH (about 7). Initial performance of the wetland with respect to Mn was encouraging, with reductions in Mn concentrations of over 50% being common during the first six years of operation. The system was modified in 1994 by adding limestone riprap below some dams and covering diversion dikes with limestone. These alterations were followed by a significant improvement in Mn removal by the system, with effluent concentrations seldom exceeding 1 mg/L. Seasonal observations indicate that Mn removal in the wetland slows during the winter. In laboratory studies, wetland limestone increased Mn removal rates by as much as 6--7 times. These rates exhibited a temperature optimum of 27 C. The rate at near 0 C was about one half that at 27 C and the rate fell to near zero at 43 C. This suggests that biological activity associated with the limestone is an important factor in the success of this wetland.

  16. 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. PMID:27048325

  17. 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.

  18. 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.

  19. 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. PMID:23500796

  20. 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.

  1. Recirculating vertical flow constructed wetland: green alternative to treating both human and animal sewage.

    PubMed

    García-Pérez, Alfredo; Harrison, Mark; Grant, Bill

    2009-11-01

    Subsurface constructed wetlands using a recirculating vertical flow are a viable alternative technology to pretreating conventional residential septic systems effluents before underground discharge. The authors examined performance of a recirculating vertical flow constructed wetland (RVFCW) to treat both human and domestic animal sewage from the LaGrange County (Indiana) Animal Shelter. Effluent water samples were analyzed for the five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), ammonia-nitrogen (AN), total Kjeldhal nitrogen (TKN), total nitrogen (TN), nitrate-nitrogen, total phosphorus (TP) and fecal coliform bacteria (FC). Treatment efficiencies (percentage removal) after a two-year operation were high for BOD5 (99%), TSS (98%), AN (96%), TKN (94%), TN (83%), and FC (99%). Nitrate-nitrogen final mean value was 6.8 mg/L, dissolved oxygen concentration increased from 1.8 to 4.3 mg/L, and removal efficiency for total phosphorus was low (33%). These results show that vertical flow constructed wetlands are a green alternative to remove pollutants generated for both human and domestic animals.

  2. Using constructed wetlands to treat biochemical oxygen demand and ammonia associated with a refinery effluent.

    PubMed

    Huddleston, G M; Gillespie, W B; Rodgers, J H

    2000-02-01

    This study evaluated the effectiveness of constructed wetlands for tertiary treatment of a petroleum refinery effluent. Specific performance objectives were to decrease 5-day biochemical oxygen demand (BOD(5)) and ammonia by at least 50% and to reduce toxicity associated with this effluent. Two bench-scale wetlands (replicates) were constructed in a greenhouse to provide tertiary treatment of effluent samples shipped from the refinery to the study site. Integrated wetland features included Typha latifolia Linnaeus planted in low organic (0.2%), sandy sediment, 48-h nominal hydraulic retention time, and 15-cm overlying water depth. Targeted constituents and aqueous toxicity were monitored in wetland inflows and outflows for 3 months. Following a 2 to 3-week stabilization period, effective and consistent removal of BOD(5) and ammonia (as NH(3)-N) from the effluent was observed. Average BOD(5) removal was 80%, while NH(3)-N decreased by an average of 95%. Survival of Pimephales promelas Rafinesque and Ceriodaphnia dubia Richard (7-day, static, renewal exposures) increased by more than 50% and 20%, respectively. Reproduction of C. dubia increased from zero in undiluted wetland inflow to 50% of controls in undiluted wetland outflow. This study demonstrated the potential for constructed wetlands to decrease BOD(5), ammonia, and toxicity in this refinery effluent.

  3. Effect of loading rate on performance of constructed wetlands treating an anaerobic supernatant.

    PubMed

    Chazarenc, F; Maltais-Landry, G; Troesch, S; Comeau, Y; Brisson, J

    2007-01-01

    The effect of organic loading, season and plant species on the treatment of fish farm effluent was tested using three-year old mesocosm wetland systems. During one year, nine 1 m2 mesocosms (horizontal subsurface flow), located in a controlled greenhouse environment, were fed with a reconstituted fish farm effluent containing a high fraction of soluble components (1,600 microS/cm and in mg/L: 230 +/- 80 COD, 179 +/- 60 sCOD, 100 +/- 40 TSS, 37 +/- 7 TKN, 14 +/- 2 TP). Combinations of three hydraulic loading rates (30, 60 and 90 L.m(-2) d(-1)) and two plant species (Phragmites australis, Typha angustifolia) and an unplanted control were tested for treatment performance and hydraulic behaviour. Loadings higher than 15 g COD m(-2) d(-1) resulted in a net decrease of hydraulic performances (generation of short circuiting) coupled with low TKN removal. Maximal TKN removal rates (summer: 1.2, winter: 0.6 g.m(-2) d(-1)) were reached in planted units. In all mesocosms, phosphorus was removed during summer (maximal removal rate: 0.3 g TP m(-2) d(-1)) and was released in winter (release rate = approximately half of summer removal rate). This study confirmed that constructed wetlands are susceptible to clogging when treating anaerobic storage tank supernatant rich in highly biodegradable compounds. Contributions of plants to hydraulic efficiency were mainly observed in summer, associated with high evapotranspiration rates. Both plant species gave a similar removal efficiency for all pollutants.

  4. Performance of a single stage vertical flow constructed wetland system treating raw domestic sewage in Brazil.

    PubMed

    Lana, L C O; Moraes, D C; von Sperling, M; Morato, M L N; Vasconcellos, G R; Paraense, M O; Moreira, T P A

    2013-01-01

    This study investigated the behaviour of two intermittently fed vertical flow constructed wetlands (one planted with Tifton 85 and the other unplanted) working in parallel, treating raw municipal sewage in Brazil for a population equivalent around 100 inhabitants. Based on a monitoring programme of over 2 years, the following items were evaluated: influence of batch frequency and the presence of Tifton 85 on the wetlands performance in terms of several physico-chemical and biological constituents. The unit with plants performed better than the one without, indicating a positive influence of the presence of plants. More attachment by total and volatile solids and larger amount of bacteria involved in the nitrogen cycle were observed in the planted filter medium, which can explain its higher nitrification and solids removal. The application of a smaller influent volume with a higher batch frequency improved the performance of both units. No signs of medium clogging have been observed in both units. The system simplicity and the good removal efficiency of organic matter, suspended solids, ammonia and helminth eggs indicate its high applicability in small communities in developing countries such as Brazil.

  5. Purification ability and carbon dioxide flux from surface flow constructed wetlands treating sewage treatment plant effluent.

    PubMed

    Wu, Haiming; Lin, Li; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Liu, Hai

    2016-11-01

    In this study, a two-year experiment was carried out to investigate variation of carbon dioxide (CO2) flux from free water surface constructed wetlands (FWS CW) systems treating sewage treatment plant effluent, and treatment performance was also evaluated. The better 74.6-76.6% COD, 92.7-94.4% NH4(+)-N, 60.1-84.7% TN and 49.3-70.7% TP removal efficiencies were achieved in planted CW systems compared with unplanted systems. The planted CW was a net CO2 sink, while the unplanted CW was a net CO2 source in the entire study period. An obvious annual and seasonal variability of CO2 fluxes from different wetland systems was also presented with the average CO2 flux ranging from -592.83mgm(-2)h(-1) to 553.91mgm(-2)h(-1) during 2012-2013. In addition, the net exchange of CO2 between CW systems and the atmosphere was significantly affected by air temperature, and the presence of plants also had the significant effect on total CO2 emissions.

  6. Purification ability and carbon dioxide flux from surface flow constructed wetlands treating sewage treatment plant effluent.

    PubMed

    Wu, Haiming; Lin, Li; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Liu, Hai

    2016-11-01

    In this study, a two-year experiment was carried out to investigate variation of carbon dioxide (CO2) flux from free water surface constructed wetlands (FWS CW) systems treating sewage treatment plant effluent, and treatment performance was also evaluated. The better 74.6-76.6% COD, 92.7-94.4% NH4(+)-N, 60.1-84.7% TN and 49.3-70.7% TP removal efficiencies were achieved in planted CW systems compared with unplanted systems. The planted CW was a net CO2 sink, while the unplanted CW was a net CO2 source in the entire study period. An obvious annual and seasonal variability of CO2 fluxes from different wetland systems was also presented with the average CO2 flux ranging from -592.83mgm(-2)h(-1) to 553.91mgm(-2)h(-1) during 2012-2013. In addition, the net exchange of CO2 between CW systems and the atmosphere was significantly affected by air temperature, and the presence of plants also had the significant effect on total CO2 emissions. PMID:27544264

  7. An analysis of the effectiveness of a constructed wetland treating acid mine drainage

    SciTech Connect

    Huddleston, G.M. III; Grant, A.J.; Ramey, B.A.

    1994-12-31

    Acid mine drainage (AMD) from an abandoned coal mine in southcentral Kentucky had pH levels as low as 2.3 and iron concentrations as high as 641 mg/L. In the summer of 1992, the US Soil Conservation Service constructed a wetland system to treat the AMD that incorporated both physical and biological treatments. The AMD was initially fed into three anoxic limestone beds followed by an aeration pond and four cattail cells. A polishing pond served as the final stage of treatment. Flow of AMD was initiated in the fall of 1992, and treatment effectiveness was monitored for the next year. Chemical analysis and the cladoceran (Ceriodaphnia dubia) survival and reproduction test were performed on water samples collected along the flow path. Water chemistry analysis and determination of toxic levels indicated a substantial increase in pH and removal of metals prior to entering the cattail cells. Water quality in the cattail cells and polishing pond varied throughout the seasons, but had improved substantially by the end of the one-year monitoring period. The use of the wetland system by macroinvertebrates also was evaluated. Results indicated that a limited number of species were found in the cattail cells, while larger numbers were recovered from the polishing pond.

  8. Vegetation effects on anammox spatial distribution and nitrogen removal in constructed wetlands treated with domestic sewage.

    PubMed

    Wang, Ling; Li, Tian

    2014-01-01

    In this study, two horizontal subsurface-flow constructed wetlands (CWs) (planted and unplanted) were constructed and compared to investigate the effects of vegetation on nitrogen removal and anammox (anaerobic ammonium oxidation) spatial distribution and enrichment. Calamus (Acorus calamus L.), which has a large root system, was selected as the vegetation. Removal of total nitrogen from the planted wetland was much higher than that from the unplanted one. Radial oxygen loss from calamus provided the planted wetland with better oxygen restoration ability, benefitting ammonium removal in the CW, especially when anammox was inhibited under winter temperatures. Enrichment of anammox bacteria in planted wetlands was much greater than that in unplanted ones. The greatest enrichment of anammox bacteria occurred in the middle layer, which had a better anaerobic environment and moderate root system. The reduced rate of metabolism in plants during winter led to a sharp decrease in anammox bacteria copy numbers in the planted wetland. Under cold temperature, the degree of enrichment with anammox bacteria in the planted wetland was similar to or slightly superior to that in the unplanted 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. 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. PMID:26809932

  11. Use of stable nitrogen isotope fractionation to estimate denitrification in small constructed wetlands treating agricultural runoff.

    PubMed

    Søvik, Anne Kristine; Mørkved, Pål Tore

    2008-03-15

    Constructed wetlands (CWs) in the agricultural landscape reduce non-point source pollution through removal of nutrients and particles. The objective of this study was to evaluate if measurements of natural abundance of (15)NO(3)(-) can be used to determine the fate of NO(3)(-) in different types of small CWs treating agricultural runoff. Nitrogen removal was studied in wetland trenches filled with different filter materials (T1--sand and gravel; T3--mixture of peat, shell sand and light-weight aggregates; T8--barley straw) and a trench formed as a shallow pond (T4). The removal was highest during summer and lowest during autumn and winter. Trench T8 had the highest N removal during summer. Measurements of the natural abundance of (15)N in NO(3)(-) showed that denitrification was not significant during autumn/winter, while it was present in all trenches during summer, but only important for nitrogen removal in trench T8. The (15)N enrichment factors of NO(3)(-) in this study ranged from -2.5 to -5.9 per thousand (T3 and T8, summer), thus smaller than enrichment factors found in laboratory tests of isotope discrimination in denitrification, but similar to factors found for denitrification in groundwater and a large CW. The low enrichment factors compared to laboratory studies was attributed to assimilation in plants/microbes as well as diffusion effect. Based on a modified version of the method presented by Lund et al. [Lund LJ, Horne AJ, Williams AE, Estimating denitrification in a large constructed wetland using stable nitrogen isotope ratios. Ecol Engineer 2000; 14: 67-76], denitrification and assimilation were estimated to account for 53 to 99 and 1 to 47%, respectively, of the total N removal during summer. This method is, however, based on a number of assumptions, and there is thus a need for a better knowledge of the effect of plant uptake, microbial assimilation as well as nitrification on N isotopic fractionation before this method can be used to evaluate

  12. Use of stable nitrogen isotope fractionation to estimate denitrification in small constructed wetlands treating agricultural runoff.

    PubMed

    Søvik, Anne Kristine; Mørkved, Pål Tore

    2008-03-15

    Constructed wetlands (CWs) in the agricultural landscape reduce non-point source pollution through removal of nutrients and particles. The objective of this study was to evaluate if measurements of natural abundance of (15)NO(3)(-) can be used to determine the fate of NO(3)(-) in different types of small CWs treating agricultural runoff. Nitrogen removal was studied in wetland trenches filled with different filter materials (T1--sand and gravel; T3--mixture of peat, shell sand and light-weight aggregates; T8--barley straw) and a trench formed as a shallow pond (T4). The removal was highest during summer and lowest during autumn and winter. Trench T8 had the highest N removal during summer. Measurements of the natural abundance of (15)N in NO(3)(-) showed that denitrification was not significant during autumn/winter, while it was present in all trenches during summer, but only important for nitrogen removal in trench T8. The (15)N enrichment factors of NO(3)(-) in this study ranged from -2.5 to -5.9 per thousand (T3 and T8, summer), thus smaller than enrichment factors found in laboratory tests of isotope discrimination in denitrification, but similar to factors found for denitrification in groundwater and a large CW. The low enrichment factors compared to laboratory studies was attributed to assimilation in plants/microbes as well as diffusion effect. Based on a modified version of the method presented by Lund et al. [Lund LJ, Horne AJ, Williams AE, Estimating denitrification in a large constructed wetland using stable nitrogen isotope ratios. Ecol Engineer 2000; 14: 67-76], denitrification and assimilation were estimated to account for 53 to 99 and 1 to 47%, respectively, of the total N removal during summer. This method is, however, based on a number of assumptions, and there is thus a need for a better knowledge of the effect of plant uptake, microbial assimilation as well as nitrification on N isotopic fractionation before this method can be used to evaluate

  13. Performance of a wall cascade constructed wetland treating surfactant-polluted water.

    PubMed

    Tamiazzo, Jessica; Breschigliaro, Simone; Salvato, Michela; Borin, Maurizio

    2015-09-01

    Carwashes are highly water-consuming processes that require wastewater treatment before discharge into a sewer system due to the complex composition of leachate. Anionic surfactants (AS) are the main constituents of this wastewater because of their cleaning and solubilization properties; they can be potentially dangerous for the environment if not adequately treated. Constructed wetlands (CWs) are low-cost systems increasingly used to treat different types of wastewater; however, there are few studies on their use for the treatment of carwash wastewater. In this study, an innovative constructed wetland arranged in a "cascade" to simulate a wall system (WCCW) was experimented in 2010 and 2011 to treat AS. Three plant species were tested at different AS inlet concentrations (10, 50, and 100 mg L(-1)) with two hydraulic retention times (HRTs; 3 and 6 days): ribbon grass (Typhoides arundinacea (L.) Moench (syn. Phalaris arundinacea L.) var. picta; Ta), water mint (Mentha aquatica L.; Ma), and divided sedge (Carex divisa Hudson; Cd). All plant species grew constantly over the experimental period, showing a capacity to tolerate even the highest AS concentration. Using the HRT of 6 days, raising the inlet concentration increased the AS outlet concentration, with similar values for the treatments (median values of 0.13-0.15, 0.47-0.78, and 1.19-1.46 mg L(-1) at inlet concentrations in the order 10, 50, and 100 mg L(-1)). The shorter HRT led to significant differences among treatments in the reduction of outlet concentration, the best result being given by the tanks vegetated with Ma (A = 97.7 % with outlet concentration 0.35 mg L(-1)). After treatments of the WCCW, the AS content was reduced almost completely, with removal in the ranges 0.07-10.2 g m(-2) day(-1) for tanks planted with Ta, 0.10-9.1 g m(-2) day(-1) for Ma tanks, and 0.11-9.5 g m(-2) day(-1) for Cd tanks depending on the inlet concentration. PMID:25586615

  14. Performance of a wall cascade constructed wetland treating surfactant-polluted water.

    PubMed

    Tamiazzo, Jessica; Breschigliaro, Simone; Salvato, Michela; Borin, Maurizio

    2015-09-01

    Carwashes are highly water-consuming processes that require wastewater treatment before discharge into a sewer system due to the complex composition of leachate. Anionic surfactants (AS) are the main constituents of this wastewater because of their cleaning and solubilization properties; they can be potentially dangerous for the environment if not adequately treated. Constructed wetlands (CWs) are low-cost systems increasingly used to treat different types of wastewater; however, there are few studies on their use for the treatment of carwash wastewater. In this study, an innovative constructed wetland arranged in a "cascade" to simulate a wall system (WCCW) was experimented in 2010 and 2011 to treat AS. Three plant species were tested at different AS inlet concentrations (10, 50, and 100 mg L(-1)) with two hydraulic retention times (HRTs; 3 and 6 days): ribbon grass (Typhoides arundinacea (L.) Moench (syn. Phalaris arundinacea L.) var. picta; Ta), water mint (Mentha aquatica L.; Ma), and divided sedge (Carex divisa Hudson; Cd). All plant species grew constantly over the experimental period, showing a capacity to tolerate even the highest AS concentration. Using the HRT of 6 days, raising the inlet concentration increased the AS outlet concentration, with similar values for the treatments (median values of 0.13-0.15, 0.47-0.78, and 1.19-1.46 mg L(-1) at inlet concentrations in the order 10, 50, and 100 mg L(-1)). The shorter HRT led to significant differences among treatments in the reduction of outlet concentration, the best result being given by the tanks vegetated with Ma (A = 97.7 % with outlet concentration 0.35 mg L(-1)). After treatments of the WCCW, the AS content was reduced almost completely, with removal in the ranges 0.07-10.2 g m(-2) day(-1) for tanks planted with Ta, 0.10-9.1 g m(-2) day(-1) for Ma tanks, and 0.11-9.5 g m(-2) day(-1) for Cd tanks depending on the inlet concentration.

  15. Performance of a constructed wetland for treating farm-yard dirty water.

    PubMed

    Forbes, E G A; Foy, R H; Mulholland, M V; Brettell, J L

    2011-01-01

    Constructed wetlands (CWs) have been used to treat agricultural effluents with varying success especially with respect to their operational efficiency in winter and ability to retain phosphorus. Dirty water (DW) from dairy farms is a mixture of manure contaminated runoff and milk parlour washings with a highly polluting biochemical oxygen demand (BOD) < or =3000 mg/L. The initial performance a CW of a 1.2 ha horizontal flow CW consisting of five ponds in series designed to treat DW from a dairy unit was assessed over four years. Ponds were earth-lined and shallow (0.3 m) with a water residence time of 100 days and planted with five species of emergent macrophytes. In comparison to CW inflow, annual reductions were as follows: BOD 99%, P 95% and N 92.8%. Coliforms were reduced by a 10(-5) factor to natural levels. From May to October there was little CW discharge due to evaporative losses. Final effluent quality was poorest in February but remained within a regulatory effluent standard for BOD of 40 mg/L. If the CW had only four ponds (25% less surface area) effluent would have failed the BOD standard in three years.

  16. Seasonal nutrient uptake of plant biomass in a constructed wetland treating piggery wastewater effluent.

    PubMed

    Lee, S Y; Maniquiz, M C; Choi, J Y; Jeong, S M; Kim, L H

    2013-01-01

    The surface-flow constructed wetland (CW) located in Nonsan City, South Korea, and constructed as the final stage of a piggery wastewater treatment plant that aims to treat high nutrient content effluent during dry days and stormwater runoff during wet days was monitored from October 2008 to November 2011. This research investigated the seasonal nutrient uptake of plant biomass in the CW and nutrient concentration changes in each treatment region under monsoon and temperate climate conditions. Results showed that the mean total nitrogen removal during summer (June to August) was higher by 13% than in spring (March to May), while total phosphorus removal was higher by 22% in fall (September to November) than in winter (December to February). All plants in the CW reached their maximum biomass coverage and weight in summer and minimum growth in winter. The highest N and P content in plants occurred in September with 583.2 g/m(2) and August with 62.0 g/m(2), respectively. Based on the results, it is recommended that the harvesting of plants should be conducted during the time of the peak nutrient uptake and before the plants release the nutrient content back to the CW. The dependence of nutrient removal efficiency on plants is not so significant. In order to increase the nutrient removal rate by plant uptake, it is suggested that the treatment regions in the CW be covered by plants.

  17. Vertical-flow constructed wetlands treating domestic wastewater contaminated by hydrocarbons.

    PubMed

    Al-Isawi, R H K; Sani, A; Almuktar, S A A A N; Scholz, M

    2015-01-01

    The aim was to compare the impact of different design (aggregate size) and operational (contact time, empty time and chemical oxygen demand (COD) loading) variables on the long-term and seasonal performance of vertical-flow constructed wetland filters operated in tidal flow mode before and after a one-off spill of diesel. Ten different vertical-flow wetland systems were planted with Phragmites australis (Cav.) Trin. ex Steud. (common reed). Approximately 130 g of diesel fuel was poured into four wetland filters. Before the spill, compliance with secondary wastewater treatment standards was achieved by all wetlands regarding ammonia-nitrogen (NH4-N), nitrate-nitrogen (NO₃-N) and suspended solids (SS), and non-compliance was recorded for biochemical oxygen demand and ortho-phosphate-phosphorus (PO₄-P). Higher COD inflow concentrations had a significantly positive impact on the treatment performance for COD, PO₄-P and SS. The wetland with the largest aggregate size had the lowest mean NO₃-N outflow concentration. However, the results were similar regardless of aggregate size and resting time for most variables. Clear seasonal outflow concentration trends were recorded for COD, NH4-N and NO₃-N. No filter clogging was observed. The removal efficiencies dropped for those filters impacted by the diesel spill. The wetlands system shows a good performance regarding total petroleum hydrocarbon (TPH) removal. PMID:25812105

  18. Vertical-flow constructed wetlands treating domestic wastewater contaminated by hydrocarbons.

    PubMed

    Al-Isawi, R H K; Sani, A; Almuktar, S A A A N; Scholz, M

    2015-01-01

    The aim was to compare the impact of different design (aggregate size) and operational (contact time, empty time and chemical oxygen demand (COD) loading) variables on the long-term and seasonal performance of vertical-flow constructed wetland filters operated in tidal flow mode before and after a one-off spill of diesel. Ten different vertical-flow wetland systems were planted with Phragmites australis (Cav.) Trin. ex Steud. (common reed). Approximately 130 g of diesel fuel was poured into four wetland filters. Before the spill, compliance with secondary wastewater treatment standards was achieved by all wetlands regarding ammonia-nitrogen (NH4-N), nitrate-nitrogen (NO₃-N) and suspended solids (SS), and non-compliance was recorded for biochemical oxygen demand and ortho-phosphate-phosphorus (PO₄-P). Higher COD inflow concentrations had a significantly positive impact on the treatment performance for COD, PO₄-P and SS. The wetland with the largest aggregate size had the lowest mean NO₃-N outflow concentration. However, the results were similar regardless of aggregate size and resting time for most variables. Clear seasonal outflow concentration trends were recorded for COD, NH4-N and NO₃-N. No filter clogging was observed. The removal efficiencies dropped for those filters impacted by the diesel spill. The wetlands system shows a good performance regarding total petroleum hydrocarbon (TPH) removal.

  19. 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. PMID:14510202

  20. Removal of Salmonella and indicator micro-organisms in integrated constructed wetlands treating agricultural wastewater.

    PubMed

    McCarthy, Gemma; Lawlor, Peadar G; Gutierrez, Montserrat; Gardiner, Gillian E

    2011-01-01

    The purpose of this study was to investigate the removal of pathogenic and indicator micro-organisms in integrated constructed wetland (ICW) systems treating agricultural wastewater. Nine ICW's treating piggery (3) or dairy (6) wastewaters were sampled and indicator micro-organisms were enumerated in the influent as well as the effluent from the first, mid- and final cells. The presence/absence of Salmonella was also determined and any Salmonella isolates recovered were characterized. Mean counts of coliform, E. coli and Enterococcus across all nine ICW systems were lower in the final effluent than in the effluent from cell 1 (P < 0.001). An antibiotic susceptible isolate of Salmonella Dublin, a bovine-adapted serotype, was isolated from the influent to one dairy ICW but was not detected in any of the ICW cells. An antibiotic sensitive Salmonella Dublin isolate with the same molecular fingerprint was also recovered from the cell 1 effluent of another dairy ICW but was absent from the influent and the mid-cell and final effluents. Salmonella Typhimurium DT104b was detected in the liquid fraction of anaerobically digested pig manure as well as in the effluent from the first cell and mid-cell of an ICW treating this material, but was absent in the final effluent. Molecular fingerprinting by pulsed field gel electrophoresis demonstrated that the recovered isolates were highly related. However, they had different antimicrobial resistance profiles, with some highly resistant isolates recovered. In conclusion, counts of indicator micro-organisms were reduced significantly within ICW, with E. coli and Enterococcus non-detectable in the final effluent. Moreover, Salmonella, when present in the influent, appears to have been removed.

  1. 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.

  2. A pilot study of a subsurface-flow constructed wetland treating membrane concentrate produced from reclaimed water.

    PubMed

    Chakraborti, Rajat K; Bays, James S; Ng, Thien; Balderrama, Lou; Kirsch, Terry

    2015-01-01

    A pilot study was conducted for 7 months for the City of Oxnard, California, on the use of constructed wetlands to treat concentrate produced by microfiltration and reverse osmosis (RO) of reclaimed wastewater. The treatment performance of a transportable subsurface-flow wetland was investigated by monitoring various forms of nitrogen, orthophosphate, oxygen demand, organic carbon, and selenium. Significant mass removal of constituents was measured under two hydraulic residence times (HRTs) (2.5 and 5 days). Inflow and outflow concentrations of nitrate-N and ammonia-N were significantly different for both HRTs, whereas nitrite-N and total organic carbon (TOC) were significantly different during HRT2. Mass removal by the constructed wetland averaged 61% of nitrate-N, 32% of nitrite-N, 42% of ammonia-N, 43% of biochemical oxygen demand, 19% of orthophosphate as P, 18% of TOC and 61% of selenium. Mass removal exceeded concentration reductions through water volume loss through evapotranspiration. Calibrated first-order area-based removal rates were consistent with literature ranges, and were greater during HRT1 consistent with greater mass loads, higher hydraulic loading and shorter HRTs. The rate constants may provide a basis for sizing a full-scale wetland receiving a similar quality of water. The results indicated that engineered wetlands can be useful in the management of RO membrane concentrate for reclaimed water reuse. PMID:26177409

  3. Temporal variation of nitrogen balance within constructed wetlands treating slightly polluted water using a stable nitrogen isotope experiment.

    PubMed

    Zhang, Wanguang; Lei, Qiongye; Li, Zhengkui; Han, Huayang

    2016-02-01

    Slightly polluted water has become one of the main sources of nitrogen contaminants in recent years, for which constructed wetlands (CW) is a typical and efficient treatment. However, the knowledge about contribution of individual nitrogen removal pathways and nitrogen balance in constructed wetlands is still limited. In this study, a stable-isotope-addition experiment was performed in laboratory-scale constructed wetlands treating slightly polluted water to determine quantitative contribution of different pathways and temporal variation of nitrogen balance using Na(15)NO3 as tracer. Microbial conversion and substrate retention were found to be the dominant pathways in nitrogen removal contributing 24.4-79.9 and 8.9-70.7 %, respectively, while plant contributed only 4.6-11.1 % through direct assimilation but promoted the efficiency of other pathways. In addition, microbial conversion became the major way to remove N whereas nitrogen retained in substrate at first was gradually released to be utilized by microbes and plants over time. The findings indicated that N2 emission representing microbial conversion was not only the major but also permanent nitrogen removal process, thus keeping a high efficiency of microbial conversion is important for stable and efficient nitrogen removal in constructed wetlands.

  4. Temporal variation of nitrogen balance within constructed wetlands treating slightly polluted water using a stable nitrogen isotope experiment.

    PubMed

    Zhang, Wanguang; Lei, Qiongye; Li, Zhengkui; Han, Huayang

    2016-02-01

    Slightly polluted water has become one of the main sources of nitrogen contaminants in recent years, for which constructed wetlands (CW) is a typical and efficient treatment. However, the knowledge about contribution of individual nitrogen removal pathways and nitrogen balance in constructed wetlands is still limited. In this study, a stable-isotope-addition experiment was performed in laboratory-scale constructed wetlands treating slightly polluted water to determine quantitative contribution of different pathways and temporal variation of nitrogen balance using Na(15)NO3 as tracer. Microbial conversion and substrate retention were found to be the dominant pathways in nitrogen removal contributing 24.4-79.9 and 8.9-70.7 %, respectively, while plant contributed only 4.6-11.1 % through direct assimilation but promoted the efficiency of other pathways. In addition, microbial conversion became the major way to remove N whereas nitrogen retained in substrate at first was gradually released to be utilized by microbes and plants over time. The findings indicated that N2 emission representing microbial conversion was not only the major but also permanent nitrogen removal process, thus keeping a high efficiency of microbial conversion is important for stable and efficient nitrogen removal in constructed wetlands. PMID:26438366

  5. Nitrogen removal performance in planted and unplanted horizontal subsurface flow constructed wetlands treating different influent COD/N ratios.

    PubMed

    Wang, Wei; Ding, Yi; Ullman, Jeffrey L; Ambrose, Richard F; Wang, Yuhui; Song, Xinshan; Zhao, Zhimiao

    2016-05-01

    Microcosm horizontal subsurface flow constructed wetlands (HSSFCWs) were used to examine the impacts of vegetation on nitrogen dynamics treating different influent COD/N ratios (1:1, 4:1, and 8:1). An increase in the COD/N ratio led to increased reductions in NO3 and total inorganic nitrogen (TIN) in planted and unplanted wetlands, but diminished removal of NH4. The HSSFCW planted with Canna indica L. exhibited a significant reduction in NH4 compared to the unplanted system, particularly in the active root zone where NH4 removal performance increased by up to 26 % at the COD/N ratio of 8:1. There was no significant difference in NO3 removal between the planted and unplanted wetlands. TIN removal efficiency in the planted wetland increased with COD/N ratios, which was likely influenced by plant uptake. NH4 reductions were greater in planted wetland at the 20- and 40-cm depths while NO3 reductions were uniformly greater with depth in all cases, but no statistical difference was impacted by depth on TIN removal. These findings show that planting a HSSFCW can provide some benefit in reducing nitrogen loads in effluents, but only when a sufficient carbon source is present.

  6. 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.

  7. 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. PMID:25339533

  8. 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.

  9. A mass balance study on nitrification and deammonification in vertical flow constructed wetlands treating landfill leachate.

    PubMed

    Sun, G; Austin, D

    2007-01-01

    A laboratory-scale, mass-balance study was carried out on the transformation of nitrogenous pollutants in four vertical flow wetland columns. Landfill leachate containing low organic matter, but a high concentration of ammoniacal-nitrogen, was treated under dissolved oxygen concentrations close to saturation. Influent total nitrogen (TN) comprised ammoniacal-nitrogen with less than 1% nitrate and nitrite, negligible organic nitrogen, and very low BOD. Nitrification occurred in three of the four columns. There was a substantial loss of total nitrogen (52%) in one column, whereas other columns exhibited zero to minor losses (< 12%). Nitrogen loss under study conditions was unexpected. Two hypotheses are proposed to account for it: (1) either the loss of TN is attributed to nitrogen transformation into a form (provisionally termed alpha-nitrogen) that is undetectable by the analytical methods used; or (2) the loss is caused by microbial denitrification or deammonification. By elimination and stoichiometric mass balance calculations, completely autotrophic nitrogen-removal over nitrite (CANON) deammonification is confirmed as responsible for nitrogen loss in one column. This result reveals that CANON can be native to aerobic engineered wetland systems treating high ammonia, low organic content wastewater.

  10. Seasonal variation in accurate identification of Escherichia coli within a constructed wetland receiving tertiary-treated municipal effluent.

    PubMed

    McLain, Jean E T; Williams, Clinton F

    2008-09-01

    As the reuse of municipal wastewater escalates worldwide as a means to extend increasingly limited water supplies, accurate monitoring of water quality parameters, including Escherichia coli (E. coli), increases in importance. Chromogenic media are often used for detection of E. coli in environmental samples, but the presence of unique levels of organic and inorganic compounds alters reclaimed water chemistry, potentially hindering E. coli detection using enzyme-based chromogenic technology. Over seven months, we monitored E. coli levels using m-Coli Blue 24 broth in a constructed wetland filled with tertiary-treated municipal effluent. No E. coli were isolated in the wetland source waters, but E. coli, total coliforms, and heterotrophic bacteria increased dramatically within the wetland on all sampling dates, most probably due to fecal inputs from resident wildlife populations. Confirmatory testing of isolates presumptive for E. coli revealed a 41% rate of false-positive identification using m-Coli Blue 24 broth over seven months. Seasonal differences were evident, as false-positive rates averaged 35% in summer, but rose sharply to 75% in the late fall and winter. Corrected E. coli levels were significantly correlated with electrical conductivity, indicating that water chemistry may be controlling bacterial survival within the wetland. This is the first study to report that accuracy of chromogenic media for microbial enumeration in reclaimed water may show strong seasonal differences, and highlights the importance of validation of microbiological results from chromogenic media for accurate analysis of reclaimed water quality.

  11. Nitrous oxide exchanges with the atmosphere of a constructed wetland treating wastewater. Parameters and implications for emission factors

    NASA Astrophysics Data System (ADS)

    Johansson, A. E.; Kasimir Klemedtsson, Å.; Klemedtsson, L.; Svensson, B. H.

    2003-07-01

    Static chamber measurements of N2O fluxes were taken during the 1998 and 1999 growth seasons in a Swedish constructed wetland receiving wastewater. The dominating plant species in different parts of the wetland were Lemna minor L., Typha latifolia L., Spirogyra sp. and Glyceria maxima (Hartm.) and Phalaris arundinacea (L.), respectively. There were large temporal and spatial variations in N2O fluxes, which ranged from consumption at -350 to emissions at 1791 μg N2O m-2 h-1. The largest positive flux occurred in October 1999 and the lowest in the middle of July 1999. The average N2O flux for the two years was 130 μg N2O m-2 h-1 (SD = 220). No significant differences in N2O fluxes were found between the years, even though the two growing seasons differed considerably with respect to both air temperature and precipitation. 15% of the fluxes were negative, showing a consumption of N2O. Consumption occurred on a few occasions at most measurement sites and ranged from 1-350 μg N2O m-2 h-1. 13-43% of the variation in N2O fluxes was explained by multiple linear regression analysis including principal components. Emission factors were calculated according to IPCC methods from the N2O fluxes in the constructed wetland. The calculated emission factors were always lower (0.02-0.27%) compared to the default factor provided by the IPCC (0.75%). Thus, direct application of the IPCC default factor may lead to overestimation of N2O fluxes from constructed wastewater-treating wetlands.

  12. Phosphorus retention in a constructed wetland system used to treat dairy wastewater.

    PubMed

    O'Neill, A; Foy, R H; Phillips, D H

    2011-04-01

    The aim of this study was to develop an input/output mass balance to predict phosphorus retention in a five pond constructed wetland system (CWS) at Greenmount Farm, County Antrim, Northern Ireland. The mass balance was created using 14-months of flow data collected at inflow and outflow points on a weekly basis. Balance outputs were correlated with meteorological parameters, such as daily air temperature and hydrological flow, recorded daily onsite. The mass balance showed that phosphorus retention within the system exceeded phosphorus release, illustrating the success of this CWS to remove nutrients from agricultural effluent from a dairy farm. The last pond, pond 5, showed the greatest relative retention of 86%. Comparison of retention and mean air temperature highlighted a striking difference in trends between up-gradient and down-gradient ponds, with up-gradient ponds 1 and 2 displaying a positive quadratic relationship and down-gradient ponds 3 through 5 displaying a negative quadratic relationship.

  13. [Characteristics and contribution of the strengthening units of composite constructed wetland for treating urban sewage].

    PubMed

    Ren, Feng; Lu, Yi-Xia; Liu, Qin; Tang, Yang-Yang; Wang, Shi-He; Gao, Hai-Ying; Qiao, Hong-Jie; Wang, Wei-Jin

    2013-02-01

    There are some defects in constructed wetland, including the uneven distribution of flow, easily blocked, lack of oxygen supply systems and the unsatisfactory phosphorus adsorption capacity of the substrates, etc. The research mainly studied the function and contribution of the pool of hydrolysis acidification, the natural reoxygenation/sinking device and strengthen slot for reducing nitrogen and phosphorus. The results showed the removal efficiency of COD and SS in hydrolysis-acidification pool accounted for 38.05% and 34.82% of the total removal efficiency of system. The SS removal efficiency of the natural reoxygenation/sinking device accounted for 22.01% of the total removal efficiency of system, and the concentration of DO kept above 2.5 mg.L-1. The two strengthen slots can ensure the TP, TN, COD up to the standard of the level 1 of GB 18918-2002.

  14. Assessment of long-term phosphorus retention in an integrated constructed wetland treating domestic wastewater.

    PubMed

    Dzakpasu, Mawuli; Scholz, Miklas; McCarthy, Valerie; Jordan, Siobhán N

    2015-01-01

    Due to the nature of the phosphorus (P) removal mechanisms associated with constructed wetlands, the sustainability of P treatment is usually of high interest. As a result, a 4-year dataset from a typical multi-celled integrated constructed wetland (ICW) located at Glaslough in Co. Monaghan, Ireland was evaluated to determine the effects of long-term P loadings and hydrological inputs on P treatment. The ICW was intensively monitored year-round from February 2008 through March 2012 for total P and molybdate reactive phosphate (MRP). Domestic wastewater was loaded at 16.4 ± 0.96 g m(2) year(-1) for total P and 11.2 ± 0.74 g m(2) year(-1) for MRP. Average mass reductions over the monitoring period were 91.4 and 90.1%, respectively. The area-based kinetic coefficients (K(20)) of 11.8 for total P and 15.6 m year(-1) for MRP indicated a high area-specific retention rate. The ICW appeared to have a sustained capacity for P adsorption and retention, but the treatment was influenced mainly by external hydrological inputs and fluctuations in wastewater loadings. Linear regression analyses showed a reduction in mass retention of both total P and MRP with increased effluent flow volumes. Monthly mass reductions exceeded 90% when the effluent flow volumes were less than 200 m(3) day(-1). When monthly effluent flow volumes exceeded 200 m(3) day(-1), nonetheless, mass reductions became highly variable. Designs and management of ICW systems should adopt measures to limit external hydrological loadings in order to maintain sufficient P treatment.

  15. Ten years experience of treating all flows from combined sewerage systems using package plant and constructed wetland combinations.

    PubMed

    Griffin, P

    2003-01-01

    Severn Trent Water have been using constructed wetlands since 1991 as part of a flowsheet in which 6 DWF (Dry Weather Flow) is treated by rotating biological contactors (RBCs), and constructed reed beds used to provide both tertiary treatment and stormwater treatment. The company now has over 50 such sites using this flowsheet. Dimensioning and effluent quality achievable is reported and data presented showing the performance of reed beds treating stormwater alone or in admixture with RBC effluent. After 8-10 years of operation the condition of a number of storm reed beds was assessed to determine the remaining asset life. The majority seem likely to achieve at least another five years of operation before further review is needed.

  16. 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.

  17. 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. PMID:26263887

  18. [Effects of constructed wetlands on treating with nitrogen and phosphorus in wastewater from hoggery].

    PubMed

    Liao, Xind; Luo, Shiming

    2002-06-01

    Using plant species Vetiveria zizanioides (VCWS) and Cyperus alternifolius (CCWS) respectively, two constructed wetlands (CWS) with size of 1.0 m x 0.5 m x 0.8 m were established. The purifying function and its change pattern among different seasons, influent concentration and hydraulic retention time (HRT) of CWS on nitrogen and phosphorus in wastewater from a hoggery was studied throughout four seasons in the year. The results showed that the effects of HRT and wastewater concentration on the removal rate of NH3-N and S-PO4(3-) were obvious in both VCWS and CCWS. High removal rates of NH3-N and S-PO4(3-) were obtained in CCWS and VCWS in spring. Significant removal of TN in wastewater existed in CCWS and VCWS in autumn, while significant removal of TP in wastewater existed only in VCWS. The removal of TP or S-PO4(3-) against the HRT in CWS followed exponential function. The rates of P removal in winter and summer changed with the influent concentrations. Under the same HRT, the change of S-PO4(3-) concentrations in outflow against the influent concentration followed a linear relationship.

  19. Biomass production of papyrus (Cyperus papyrus) in constructed wetland treating low-strength domestic wastewater.

    PubMed

    Perbangkhem, Thaneeya; Polprasert, Chongchin

    2010-01-01

    In this study, the pilot-scale constructed wetlands were fed with low-strength domestic wastewater to investigate the energy-capturing efficiency and plant productivity. Papyrus was a selected emergent macrophyte planted in the systems. The wastewater was intermittently fed to the systems, corresponding to the organic loading rates of 10, 16, 31, and 63 kg BOD/ha-d. With abundant sunshine in the tropical-climate area, papyrus converted solar radiation to biomass of about 2200-3100 g dry weight/m(2) from the two-month period of the experiments. Furthermore, the energy contents of papyrus are 16.2, 17.2, and 16.8 MJ/kg for culms, umbels, and total above-ground parts, respectively. From the plant productivity and the energy contents of papyrus obtained from this study, the energy capturing efficiencies can be estimated to be in the range of 4.4-6.0%, which are relatively high, compared with those of other plants. PMID:19758797

  20. Influences of plant type on bacterial and archaeal communities in constructed wetland treating polluted river water.

    PubMed

    Long, Yan; Yi, Hao; Chen, Sili; Zhang, Zhengke; Cui, Kai; Bing, Yongxin; Zhuo, Qiongfang; Li, Bingxin; Xie, Shuguang; Guo, Qingwei

    2016-10-01

    Both bacteria and archaeal communities can play important roles in biogeochemical processes in constructed wetland (CW) system. However, the influence of plant type on microbial community in surface water CW remains unclear. The present study investigated bacterial and archaeal communities in five surface water CW systems with different plant species. The abundance, richness, and diversity of both bacterial and archaeal communities considerably differed in these five CW systems. Compared with the other three CW systems, the CW systems planted with Vetiveria zizanioides or Juncus effusus L. showed much higher bacterial abundance but lower archaeal abundance. Bacteria outnumbered archaea in each CW system. Moreover, the CW systems planted with V. zizanioides or J. effusus L. had relatively lower archaeal but higher bacterial richness and diversity. In each CW system, bacterial community displayed much higher richness and diversity than archaeal community. In addition, a remarkable difference of both bacterial and archaeal community structures was observed in the five studied CW systems. Proteobacteria was the most abundant bacterial group (accounting for 33-60 %). Thaumarchaeota organisms (57 %) predominated in archaeal communities in CW systems planted with V. zizanioides or J. effusus L., while Woesearchaeota (23 or 24 %) and Euryarchaeota (23 or 15 %) were the major archaeal groups in CW systems planted with Cyperus papyrus or Canna indica L. Archaeal community in CW planted with Typha orientalis Presl was mainly composed of unclassified archaea. Therefore, plant type exerted a considerable influence on microbial community in surface water CW system. PMID:27392623

  1. Performance of two small subsurface flow constructed wetlands treating domestic wastewaters in Italy.

    PubMed

    Mietto, Anna; Borin, Maurizio

    2013-01-01

    The performance of a vertical and a horizontal subsurface flow wetland (v-SSF and h-SSF), designed for treating domestic wastewater from a single family, was investigated by monitoring total nitrogen (TN), nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total phosphorus (TP), chemical oxygen demand (COD) and the dissolved oxygen (DO) content of the influent and the effluent wastewater of each system during the first two years of operation. The growth of Phragmites australis in each system was recorded by measuring the height and observing their general conditions. The treated domestic wastewater presented similar chemical-physical characteristics in the two systems which operated in analogous environmental conditions. The median influent characteristics were: TN 81.9mg L(-1), NO3-N 0.19 mg L(-1), NH4-N 33.5 mg L(-1), TP 11.9 mg L(-1) and COD 354.5 mg L(-1). During the whole monitoring period median reductions in the v-SSF were TN 71%, NH4-N 94%, TP 27% and COD 92% whereas in the h-SSF they were TN 59%, NH4-N 21%, TP 52% and COD 70%. Internal production of NO3-N was observed, mainly in the v-SSF probably due to the difference in oxygen availability in the medium and the design of the system. DO concentration increased in the effluents in both years, with higher values measured in v-SSF than in h-SSF. The reduction performance increased in the second year, particularly in v-SSF, whereas no statistical differences were observed between spring-summer and autumn-winter periods. P. australis reached maximum development at the end of summer in both systems and maintained a stable height during autumn-winter. In h-SSF the vegetation located close to the influent showed lower growth than in the rest of the bed.

  2. Recirculation or artificial aeration in vertical flow constructed wetlands: a comparative study for treating high load wastewater.

    PubMed

    Foladori, Paola; Ruaben, Jenny; Ortigara, Angela R C

    2013-12-01

    Vertical subsurface-flow constructed wetlands at pilot-scale have been applied to treat high hydraulic and organic loads by implementing the following configurations: (1) intermittent recirculation of the treated wastewater from the bottom to the top of the bed, (2) intermittent artificial aeration supplied at the bottom of the bed and (3) the combination of both. These configurations were operated with a saturated bottom layer for a 6h-treatment phase, followed by a free drainage phase prior to a new feeding. COD removal efficiency was 85-90% in all the configurations and removed loads were 54-70 gCOD m(-2)d(-1). The aerated and recirculated wetland resulted in a higher total nitrogen removal (8.6 gN m(-2)d(-1)) due to simultaneous nitrification/denitrification, even in the presence of intermittent aeration (6.8 Nm(3)m(-2)d(-1)). The extra investment needed for implementing aeration/recirculation would be compensated for by a reduction of the surface area per population equivalent, which decreased to 1.5m(2)/PE.

  3. Nitrogen and phosphorus distribution in a constructed wetland fed with treated swine slurry from an anaerobic lagoon.

    PubMed

    Villamar, Cristina A; Rivera, Diego; Neubauer, Maria E; Vidal, Gladys

    2015-01-01

    Nitrogen and phosphorus distribution in a constructed wetland fed with treated swine slurry from an anaerobic lagoon were studied. The methodology considered a daily meteorological monitoring site. During 2011 to 2012, water, soil and plants (Schoenoplectus californicus (C.A. Méyer) Sójak, Typha angustifolia (L.)) were seasonally sampled (spring and fall) into the constructed wetland. During study period, results showed that rainfall was the main factor of maintenance hydraulic conditions, while evapotranspiration was driver of variations in water storage level. Nitrogen and phosphorus removal from the water phase were up to 54% and 37%, respectively. Onto soil were adsorbed over 70% nitrogen and 65% phosphorus. Phosphorus was less mobile than nitrogen, since it was bound to oxides Fe-Mn. Inorganic nitrogen species were affected by level water and seasonal vegetable maturation. During spring, N-NH4(+) was the predominant soil species, while in the fall, N-NO3(-) was dominant near the belowground part of Sc and NH4(+) near to the belowground zone of Ta. In addition, nutrients uptake was less than 30% with 64% aboveground-spring and 85% belowground-fall for both plants. Findings showed nitrification process evidences when water levels are below 0.1 m.

  4. Environmental impact of irrigation with greywater treated by recirculating vertical flow constructed wetlands in two climatic regions.

    PubMed

    Gross, Amit; Alfiya, Yuval; Sklarz, Menachem; Maimon, Adi; Friedler, Eran

    2014-01-01

    Reuse of greywater (GW) has raised environmental and public health concerns. Specifically, these concerns relate to onsite treatment operated by non-professionals; systems must therefore be reliable, simple to use and also economically feasible if they are to be widely used. The aims of this study were to: (a) investigate GW treatment efficiency using 20 full-scale recirculating vertical flow constructed wetlands (RVFCWs) operated in households in arid and Mediterranean regions; and (b) study the long-term effects of irrigation with treated GW on soil properties. RVFCW systems were installed and monitored routinely over 3 years. Raw, treated and disinfected treated GW samples were analyzed for various physicochemical and microbial parameters. Native soil plots and nearby freshwater (FW) and treated GW irrigated soil plots were sampled twice a year - at the end of the winter and at the end of the summer. Soil samples were analyzed for various physicochemical and microbial parameters. Overall, the RVFCW proved to be a robust and reliable GW treatment system. The treated GW quality met strict Israeli regulations for urban irrigation. Results also suggest that irrigation with sufficiently treated GW has no adverse effects on soil properties. Yet, continued monitoring to follow longer term trends is recommended.

  5. Water reduction by constructed wetlands treating waste landfill leachate in a tropical region.

    PubMed

    Ogata, Yuka; Ishigaki, Tomonori; Ebie, Yoshitaka; Sutthasil, Noppharit; Chiemchaisri, Chart; Yamada, Masato

    2015-10-01

    One of the key challenges in landfill leachate management is the prevention of environmental pollution by the overflow of untreated leachate. To evaluate the feasibility of constructed wetlands (CWs) for the treatment of waste landfill leachate in tropical regions, water reduction and pollutant removal by a CW subjected to different flow patterns (i.e., horizontal subsurface flow (HSSF) and free water surface (FWS)) were examined in both rainy and dry seasons in Thailand. A pilot-scale CW planted with cattail was installed at a landfill site in Thailand. With HSSF, the CW substantially removed pollutants from the landfill leachate without the need to harvest plants, whereas with FWS, it only slightly removed pollutants. Under both flow patterns, the CW significantly reduced the leachate volume to a greater extent than surface evaporation, which is regarded as an effect of the storage pond. Additionally, water reduction occurred regardless of season and precipitation, within the range 0-9 mm d(-1). In the case of low feeding frequency, water reduction by the CW with HSSF was lower than that with FWS. However, high feeding frequency improved water reduction by the CW with HSSF and resulted in a similar reduction to that observed with FWS, which exhibited maximum evapotranspiration. In terms of water reduction, with both HSSF in conjunction with high frequency feeding and FWS, the CW provided a high degree of evapotranspiration. However, pollutant removal efficiencies with HSSF were higher than for FWS. The present study suggested that CWs with HSSF and high frequency feeding could be useful for the prevention of uncontrollable dispersion of polluted leachate in the tropical climate zone.

  6. Water reduction by constructed wetlands treating waste landfill leachate in a tropical region.

    PubMed

    Ogata, Yuka; Ishigaki, Tomonori; Ebie, Yoshitaka; Sutthasil, Noppharit; Chiemchaisri, Chart; Yamada, Masato

    2015-10-01

    One of the key challenges in landfill leachate management is the prevention of environmental pollution by the overflow of untreated leachate. To evaluate the feasibility of constructed wetlands (CWs) for the treatment of waste landfill leachate in tropical regions, water reduction and pollutant removal by a CW subjected to different flow patterns (i.e., horizontal subsurface flow (HSSF) and free water surface (FWS)) were examined in both rainy and dry seasons in Thailand. A pilot-scale CW planted with cattail was installed at a landfill site in Thailand. With HSSF, the CW substantially removed pollutants from the landfill leachate without the need to harvest plants, whereas with FWS, it only slightly removed pollutants. Under both flow patterns, the CW significantly reduced the leachate volume to a greater extent than surface evaporation, which is regarded as an effect of the storage pond. Additionally, water reduction occurred regardless of season and precipitation, within the range 0-9 mm d(-1). In the case of low feeding frequency, water reduction by the CW with HSSF was lower than that with FWS. However, high feeding frequency improved water reduction by the CW with HSSF and resulted in a similar reduction to that observed with FWS, which exhibited maximum evapotranspiration. In terms of water reduction, with both HSSF in conjunction with high frequency feeding and FWS, the CW provided a high degree of evapotranspiration. However, pollutant removal efficiencies with HSSF were higher than for FWS. The present study suggested that CWs with HSSF and high frequency feeding could be useful for the prevention of uncontrollable dispersion of polluted leachate in the tropical climate zone. PMID:26209341

  7. 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)

  8. Stable isotope fractionation related to microbial nitrogen turnover in constructed wetlands treating contaminated groundwater

    NASA Astrophysics Data System (ADS)

    Voloshchenko, O.; Knoeller, K.

    2013-12-01

    To improve the efficiency of ground- and wastewater treatment in constructed wetlands (CWs), better understanding of the occurring processes is necessary. This research explores N-isotope fractionations associated with the removal of ammonium from contaminated groundwater in pilot-scale CWs downstream of the chemical industrial area Leuna, Germany. The groundwater at the site is contaminated mainly by organic (BTEX, MTBE) and inorganic compounds (ammonium). We assume that the anaerobic ammonium oxidation (ANAMMOX) plays an important role in nitrogen removal in these CWs. However, to date, interactions between processes of aerobic and anaerobic ammonium oxidation in CWs still have not been well explored. Especially, the importance of the ANAMMOX process for the nitrogen removal is generally accepted, but its role in CWs is quite unknown. For this aim, three CWs were chosen: planted horizontal subsurface flow (HSSF); unplanted HSSF, and floating plant root mat (FPRM). Water samples were taken at the inflow and outflow as well as from the pore space at different distances (1, 2.5 and 4 m) from the inlet and at different depths (20, 30 and 40 cm in the HSSF-CWs, 30 cm in the FPRM). Samples were collected in a time interval of 1 to 6 weeks during 1 year with the exception of the winter season. Physicochemical parameters, nitrogen isotope signatures of ammonium, as well as nitrogen and oxygen isotope signatures of nitrate were analysed. Within the CWs, spatial concentration gradients of the nitrogen species (ammonium and nitrate) are observed. N-isotope variations of ammonium and nitrate are interpreted according to the prevailing processes of the N-transformations. Based on isotope mass-balance approach microbial processes such as nitrification, denitrification, and ANAMMOX are quantified. DNA from biofilms at roots and gravel was extracted using FastDNA Spin Kit For Soil (MP Biomedicals). PCR, quantitative PCR, cloning, and sequencing were applied with the purpose of

  9. Carbon and nitrogen dynamics and greenhouse gas emissions in constructed wetlands treating wastewater: a review

    NASA Astrophysics Data System (ADS)

    Jahangir, M. M. R.; Richards, K. G.; Healy, M. G.; Gill, L.; Müller, C.; Johnston, P.; Fenton, O.

    2016-01-01

    The removal efficiency of carbon (C) and nitrogen (N) in constructed wetlands (CWs) is very inconsistent and frequently does not reveal whether the removal processes are due to physical attenuation or whether the different species have been transformed to other reactive forms. Previous research on nutrient removal in CWs did not consider the dynamics of pollution swapping (the increase of one pollutant as a result of a measure introduced to reduce a different pollutant) driven by transformational processes within and around the system. This paper aims to address this knowledge gap by reviewing the biogeochemical dynamics and fate of C and N in CWs and their potential impact on the environment, and by presenting novel ways in which these knowledge gaps may be eliminated. Nutrient removal in CWs varies with the type of CW, vegetation, climate, season, geographical region, and management practices. Horizontal flow CWs tend to have good nitrate (NO3-) removal, as they provide good conditions for denitrification, but cannot remove ammonium (NH4+) due to limited ability to nitrify NH4+. Vertical flow CWs have good NH4+ removal, but their denitrification ability is low. Surface flow CWs decrease nitrous oxide (N2O) emissions but increase methane (CH4) emissions; subsurface flow CWs increase N2O and carbon dioxide (CO2) emissions, but decrease CH4 emissions. Mixed species of vegetation perform better than monocultures in increasing C and N removal and decreasing greenhouse gas (GHG) emissions, but empirical evidence is still scarce. Lower hydraulic loadings with higher hydraulic retention times enhance nutrient removal, but more empirical evidence is required to determine an optimum design. A conceptual model highlighting the current state of knowledge is presented and experimental work that should be undertaken to address knowledge gaps across CWs, vegetation and wastewater types, hydraulic loading rates and regimes, and retention times, is suggested. We recommend that

  10. Performance of a sub-surface flow constructed wetland in polishing pre-treated wastewater-a tropical case study.

    PubMed

    Kaseva, M E

    2004-02-01

    This paper reports on the performance of three units of a sub-surface horizontal flow constructed wetland (CW) pilot plant in polishing effluent from the upflow anaerobic sludge blanket (UASB) reactor plant. Studies on the use of UASB for on-site wastewater pre-treatment were initiated in Tanzania for the first time in 1993, while initial research works on the application of CW for polishing effluent from UASB, the results of which are reported in this paper began in 1999. In this study the UASB reactor plant received and pre-treated part of the wastewater from the student's hostels at the University College of Lands and Architectural Studies in Tanzania. Out of the three units, unit B was planted with Phragmites mauritianus, unit C with Typha latifolia and A was used as a control. Both P.mauritianus and T.latifolia have been extensively researched in Europe and USA as suitable species of vegetation in CW. However, very limited studies on the suitability of these wetland plants have been reported under tropical climate. The studied parameters were chemical oxygen demand (COD), nitrate (NO(3)-N), nitrite (NO(2)-N), ammonium (NH(4)-N), faecal coliforms (FC), total coliforms (TC), pH, temperature and dissolved oxygen (DO). The study was carried out at an average hydraulic retention time of 1.93 days (1.85 in unit A, 1.96 in unit B and 1.99 in unit C) obtained as a ratio of the volume of wastewater in the wetland and the volumetric flow rate of wastewater through the wetland unit while taking into consideration the porosity of the media. Better performance for the vegetated units B and C were obtained compared to the control unit A. Nutrients were least removed in all units (NH(4)-N 11.2%, 25.2% and 23% in units A, B and C, respectively, NO(3)-N 32.2%, 40.3% and 44.3% for units A, B and C, respectively, and NO(2)-N 23.9%, 38.5% and 23.1% for units A, B and C, respectively). The COD removal rate was 33.6%, 56.3% and 60.7% for units A, B and C, respectively. The study

  11. 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. PMID:26247691

  12. 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.

  13. The Constructed Wetland Association UK database of constructed wetland systems.

    PubMed

    Cooper, P

    2007-01-01

    There are now more than 1,000 constructed wetland systems (CWs) in the UK. The first UK CW database was constructed by Water Research Centre (WRc) and Severn Trent Water Ltd to accompany a book on the design and performance of these systems. In that database, constructed by Gareth Job et al., only 154 beds were listed, most of which were tertiary sewage treatment sites in Severn Trent Water. The Constructed Wetland Association (CWA) was formed in 2000 as a UK water industry body in response to problems caused by unscrupulous constructors. A group of experienced, reputable designers and constructors formed the CWA to bring together best UK practice in order to counteract this problem. The group contains major water companies, designers, constructors, academics, plant growers and operators. They decided that one of the best ways of countering the problem was to assemble a database of design and performance from well-designed systems. After negotiation the CWA group took over responsibility for the database from WRc. The CWA has produced eight updates of the database which now contains information from more than 900 beds. It contains examples of the different variants of CWs in use in the UK. Most of these sites treat sewage/domestic wastewater but the database also includes examples of systems for the treatment of minewater, sludge, landfill leachate, industrial effluents, surface runoff and road runoff. Particular treatment applications are illustrated by case studies which are summary articles describing design, construction and performance. PMID:17802831

  14. Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California

    USGS Publications Warehouse

    Stumpner, Elizabeth B.; Kraus, Tamara E.C.; Fleck, Jacob A.; Hansen, Angela M.; Bachand, Sandra M.; Horwath, William R.; DeWild, John F.; Krabbenhoft, David P.; Bachand, Philip A.M.

    2015-09-02

    Following coagulation, but prior to passage through the wetland cells, coagulation treatments transferred dissolved mercury and carbon to the particulate fraction relative to untreated source water: at the wetland cell inlets, the coagulation treatments decreased concentrations of filtered total mercury by 59–76 percent, filtered monomethyl mercury by 40–70 percent, and dissolved organic carbon by 65–86 percent. Passage through the wetland cells decreased the particulate fraction of mercury in wetland cells that received coagulant-treated water. Changes in total mercury, monomethyl mercury, and dissolved organic carbon concentrations resulting from wetland passage varied both by treatment and season. Despite increased monomethyl mercury in the filtered fraction during wetland passage between March and August, the coagulation-wetland systems generally decreased total mercury (filtered plus particulate) and monomethyl mercury (filtered plus particulate) concentrations relative to source water. Coagulation—either alone or in association with constructed wetlands—could be an effective way to decrease concentrations of mercury and dissolved organic carbon in surface water as well as the bioavailability of mercury in the Sacramento–San Joaquin Delta.

  15. Can constructed wetlands treat wastewater for reuse in agriculture? Review of guidelines and examples in South Europe.

    PubMed

    Lavrnić, Stevo; Mancini, Maurizio L

    2016-01-01

    South Europe is one of the areas negatively affected by climate change. Issues with water shortage are already visible, and are likely to increase. Since agriculture is the biggest freshwater consumer, it is important to find new water sources that could mitigate the climate change impact. In order to overcome problems and protect the environment, a better approach towards wastewater management is needed. That includes an increase in the volume of wastewater that is treated and a paradigm shift towards a more sustainable system where wastewater is actually considered as a resource. This study evaluates the potential of constructed wetlands (CWs) to treat domestic wastewater and produce effluent that will be suitable for reuse in agriculture. In South Europe, four countries (Greece, Italy, Portugal and Spain) have national standards that regulate wastewater reuse in agriculture. Wastewater treatment plants (WWTPs) that are based on CWs in these four countries were analysed and their effluents compared with the quality needed for reuse. In general, it was found that CWs have trouble reaching the strictest standards, especially regarding microbiological parameters. However, their effluents are found to be suitable for reuse in areas that do not require water of the highest quality. PMID:27232397

  16. Can constructed wetlands treat wastewater for reuse in agriculture? Review of guidelines and examples in South Europe.

    PubMed

    Lavrnić, Stevo; Mancini, Maurizio L

    2016-01-01

    South Europe is one of the areas negatively affected by climate change. Issues with water shortage are already visible, and are likely to increase. Since agriculture is the biggest freshwater consumer, it is important to find new water sources that could mitigate the climate change impact. In order to overcome problems and protect the environment, a better approach towards wastewater management is needed. That includes an increase in the volume of wastewater that is treated and a paradigm shift towards a more sustainable system where wastewater is actually considered as a resource. This study evaluates the potential of constructed wetlands (CWs) to treat domestic wastewater and produce effluent that will be suitable for reuse in agriculture. In South Europe, four countries (Greece, Italy, Portugal and Spain) have national standards that regulate wastewater reuse in agriculture. Wastewater treatment plants (WWTPs) that are based on CWs in these four countries were analysed and their effluents compared with the quality needed for reuse. In general, it was found that CWs have trouble reaching the strictest standards, especially regarding microbiological parameters. However, their effluents are found to be suitable for reuse in areas that do not require water of the highest quality.

  17. Evaluation of a hybrid constructed wetland for treating domestic sewage from individual housing units surrounding agricultural villages in South Korea.

    PubMed

    Seo, Dong Cheol; DeLaune, Ronald D; Park, Woo Young; Lim, Jong Sir; Seo, Jeoung Yoon; Lee, Do Jin; Cho, Ju Sik; Heo, Jong Soo

    2009-01-01

    The treatment efficiency of 2- and 3-stage constructed wetlands (CWs) was evaluated for treating domestic sewage from houses surrounding agricultural villages. The optimum depth of filter media was 90 cm. The optimum volume ratio of vertical flow (VF) and horizontal flow (HF) beds was 1:2, and the optimum filter medium was broken stone in the VF-HF 2-stage hybrid CWs. Based on the above optimum conditions, removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (T-N), and total phosphorus (T-P) were 99, 98, 99, 68, and 72%, respectively. However to utilize constructed wetlands (CWs) for treating domestic sewage for an individual house, would require downsizing of the 2-stage hybrid CWs. In addition, the low removal efficiency of T-N and T-P in 2-stage hybrid CWs would require improvements necessary to meet acceptable water quality discharge standards. Thus, to reduce the CWs' area and improve the T-N and T-P removal efficiencies, VF-HF 2-stage hybrid CW was modified into VF/HF(I)-HF(II) and VF/HF(I)-HF(III) 3-stage hybrid CW. The optimum reduced size of 3-stage hybrid CW was the VF/HF(I)-HF(II) configuration which also increased T-N removal. Using this system, removal efficiency of BOD, COD, SS, T-N, and T-P were 99, 98, 99, 83, and 75%, respectively. In VF/HF(I)-HF(II) CW, the removal velocity of BOD, COD and SS was rapid on the order of VF (1st stage) > HF(II) (3rd stage) > or = HF(I) (2nd stage), VF (1st stage) > HF(II) (3rd stage) > HF(I) (2nd stage) and VF (1st stage) > HF(I) (2nd stage) > HF(II) (3rd stage), respectively. The removal velocity of T-N and T-P in VF/HF(I)-HF(II) CWs was rapid on the order of HF(I) (2nd stage) > HF(II) (3rd stage) > or = VF (1st stage) and VF (1st stage) > HF(I) (2nd stage) > HF(II) (3rd stage), respectively.

  18. Microbial populations identified by fluorescence in situ hybridization in a constructed wetland treating acid coal mine drainage

    SciTech Connect

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

    2006-07-15

    Microorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised of Fe(III) precipitates, were collected from two treatment cells of the constructed wetland system. The pH of the bulk samples ranged between pH 2.1 and 3.9. Viable counts of acidophilic Fe and S oxidizers and heterotrophs were determined with a most probable number (MPN) method. The MPN counts were only a fraction of the corresponding FISH counts. The sediment samples contained microorganisms in the Bacteria (including the subgroups of acidophilic Fe- and S-oxidizing bacteria and Acidiphilium spp.) and Eukarya domains. Archaea were present in the sediment surface samples at < 0.01% of the total microbial community. The most numerous bacterial species in this wetland system was Acidithiobacillus ferrooxidans, comprising up to 37% of the bacterial population. Acidithiobacillus thiooxidans was also abundant.

  19. Preliminary evaluation of a constructed wetland for treating extremely alkaline (pH 12) steel slag drainage.

    PubMed

    Mayes, W M; Aumônier, J; Jarvis, A P

    2009-01-01

    High pH (> 12) leachates are an environmental problem associated with drainage from lime (CaO)-rich industrial residues such as steel slags, lime spoil and coal combustion residues. Recent research has highlighted the potential for natural ('volunteer') wetlands to buffer extremely alkaline influent waters. This appears ascribable to high CO(2) partial pressures in the wetland waters from microbial respiration, which accelerates precipitation of calcium carbonate (CaCO(3)), and the high specific surface area for mineral precipitation offered by macrophytes. The research presented here builds on this and provides preliminary evaluation of a constructed wetland built in March 2008 to buffer drainage from steel slag heaps in north-east England. The drainage water from the slag mounds is characterised by a mean pH of 11.9, high concentrations of Ca (up to 700 mg/L), total alkalinity (up to 800 mg/L as CaCO(3)) and are slightly brackish (Na = 300 mg/L; Cl = 400 mg/L) reflecting native groundwaters at this coastal setting. Documented calcite precipitation rates (mean of 5 g CaCO(3)/m(2)/day) from nearby volunteer sites receiving steel slag drainage were used to scale the constructed wetland planted with Phragmites australis; a species found to spontaneously grow in the vicinity of the discharge. Improved performance of the wetland during summer months may at least in part be due to biological activity which enhances rates of calcite precipitation and thus lowering of pH. Secondary Ca-rich precipitates also serve as a sink for some trace elements present at low concentrations in the slag leachate such as Ni and V. The implications for scaling and applying constructed wetlands for highly alkaline drainage are discussed.

  20. Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water.

    PubMed

    Dong, Huiyu; Qiang, Zhimin; Li, Tinggang; Jin, Hui; Chen, Weidong

    2012-01-01

    Three lab-scale vertical-flow constructed wetlands (VFCWs), including the non-aerated (NA), intermittently aerated (IA) and continuously aerated (CA) ones, were operated at different hydraulic loading rates (HLRs) to evaluate the effect of artificial aeration on the treatment efficiency of heavily polluted river water. Results indicated that artificial aeration increased the dissolved oxygen (DO) concentrations in IA and CA, which significantly favored the removal of organic matter and NH(4+)-N. The DO grads caused by intermittent aeration formed aerobic and anoxic regions in IA and thus promoted the removal of total nitrogen (TN). Although the removal efficiencies of COD(Cr), NH(4+)-N and TN in the three VFCWs all decreased with an increase in HLR, artificial aeration enhanced the reactor resistance to the fluctuation of pollutant loadings. The maximal removal efficiencies of COD(Cr), NH(4+)-N and total phosphorus (TP) (i.e., 81%, 87% and 37%, respectively) were observed in CA at 19 cm/day HLR, while the maximal TN removal (i.e., 57%) was achieved in IA. Although the improvement of artificial aeration on TP removal was limited, this study has demonstrated the feasibility of applying artificial aeration to VFCWs treating polluted river water, particularly at a high HLR.

  1. Dynamics of sulphur compounds in horizontal sub-surface flow laboratory-scale constructed wetlands treating artificial sewage.

    PubMed

    Wiessner, A; Rahman, K Z; Kuschk, P; Kästner, M; Jechorek, M

    2010-12-01

    The knowledge regarding the dynamics of sulphur compounds inside constructed wetlands is still insufficient. Experiments in planted (Juncus effusus) and unplanted horizontal sub-surface-flow laboratory-scale constructed wetlands fed with artificial wastewater were carried out to evaluate the sulphate reduction, the composition and dynamics of generated sulphur compounds, as well as the influence of carbon load and plants on processes of sulphur transformation. In planted and unplanted wetlands, the addition of organic carbon (TOC of about 120 mg L(-1)) immediately affected the transformation of up to 90% of the incoming sulphate (150 mg L(-1)), directing it mainly towards elemental sulphur (30%) and sulphide (8%). During this experimental period, nearly 52% of the transformed sulphate-sulphur was calculated to be immobilized inside the planted wetland and 66% inside the unplanted one. In subsequent experiments, the deficiency of organic carbon inside the planted wetlands favoured the decrease of elemental sulphur in the pore water coupled to retransformation of depot-sulphur to dissolved sulphate. Nearly 90% of the deposited and reduced sulphur was found to be reoxidized. In principle, the results indicate a substantial improvement of this reoxidation of sulphur by oxygen released by the helophytes. Surplus of organic carbon promotes the ongoing sulphate reduction and the stability of deposed and dissolved reduced sulphur compounds. In contrast, inside the unplanted control wetland, a relative stability of the formed sulphur depots and the generated amount of dissolved sulphur compounds including elemental sulphur could be observed independently of the different loading conditions.

  2. Effluent quality and reuse potential of domestic wastewater treated in a pilot-scale hybrid constructed wetland system.

    PubMed

    Ayaz, Selma Ç; Aktaş, Özgür; Akça, Lütfi; Fındık, Nur

    2015-06-01

    The study investigates treatment and reuse potential of domestic wastewater of a small community of about 30 people sequentially by anaerobic pretreatment followed by horizontal (HSSF-CW) and vertical (VSSF-CW) sub-surface flow constructed wetlands operated in series. The organic and suspended solids load to the hybrid wetland system was decreased by anaerobic pretreatment. HSSF-CW mainly removed organic matter and supported denitrification whereas VSSF-CW mainly obtained nitrification and phosphorus removal. Recirculation of the effluent increased particularly total nitrogen removal in the wetland system. The study involves evaluation of the whole system in terms of effluent quality. It was achieved on average >95% organic matter and >90% nitrogen removal in the hybrid constructed wetland system with anaerobic pretreatment at a specific wetland surface area of only about 1 m(2) per person. Average mass removal rates were 21.17 gCOD/m(2)day, 5.58 gBOD5/m(2)day, 2.78 gTKN/m(2)day, 1.35 gTN/m(2)day, 0.44 gTP/m(2)day and 5.21 gTSS/m(2)day throughout the total duration of the operation. Consequently, the effluent met the regulations for discharge limits for organic matter and suspended solids. COD and TN concentrations decreased to below 20 mg/L in the effluent. It was also shown that effluent of the system could be reused for irrigation if it is disinfected properly.

  3. Effluent quality and reuse potential of domestic wastewater treated in a pilot-scale hybrid constructed wetland system.

    PubMed

    Ayaz, Selma Ç; Aktaş, Özgür; Akça, Lütfi; Fındık, Nur

    2015-06-01

    The study investigates treatment and reuse potential of domestic wastewater of a small community of about 30 people sequentially by anaerobic pretreatment followed by horizontal (HSSF-CW) and vertical (VSSF-CW) sub-surface flow constructed wetlands operated in series. The organic and suspended solids load to the hybrid wetland system was decreased by anaerobic pretreatment. HSSF-CW mainly removed organic matter and supported denitrification whereas VSSF-CW mainly obtained nitrification and phosphorus removal. Recirculation of the effluent increased particularly total nitrogen removal in the wetland system. The study involves evaluation of the whole system in terms of effluent quality. It was achieved on average >95% organic matter and >90% nitrogen removal in the hybrid constructed wetland system with anaerobic pretreatment at a specific wetland surface area of only about 1 m(2) per person. Average mass removal rates were 21.17 gCOD/m(2)day, 5.58 gBOD5/m(2)day, 2.78 gTKN/m(2)day, 1.35 gTN/m(2)day, 0.44 gTP/m(2)day and 5.21 gTSS/m(2)day throughout the total duration of the operation. Consequently, the effluent met the regulations for discharge limits for organic matter and suspended solids. COD and TN concentrations decreased to below 20 mg/L in the effluent. It was also shown that effluent of the system could be reused for irrigation if it is disinfected properly. PMID:25841192

  4. Biomonitoring study of a constructed wetland site treating acid mine drainage. Research report, July 1990-June 1992

    SciTech Connect

    Ramey, B.A.; Halverson, H.G.; Taylor, L.A.

    1992-01-01

    Acid Mine Drainage (AMD) from an underground coal mine in the Jones Branch watershed in McCreary County, KY, substantially reduced water quality in Jones Branch. Downstream from the mine seeps, the pH was routinely below 4.5 and concentrations of most heavy metals, especially iron, were elevated. A cattail wetland (1,022 m2) was constructed on Jones Branch in 1989 to obviate the effects of the AMD. Monthly chemical monitoring was performed on the water from above, from below, and from the 26 cells within the wetland. Based on chemical monitoring, the wetland initially improved water quality, increasing the pH and removing substantial amounts of heavy metals. Beginning in the spring of 1991, water quality at the wetland outfall began to decline, and has not improved to date. To augment the chemical monitoring, a biomonitoring study was initiated in the spring of 1990. Acute 48-hr. static tests were conducted with newly hatched fathead minnows (Pimephales promelas). Median lethal concentration (LC50) values determined monthly reflects the decline in water quality at the outfall over time.

  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. Evaluation of PPCPs removal in a combined anaerobic digester-constructed wetland pilot plant treating urban wastewater.

    PubMed

    Reyes-Contreras, C; Matamoros, V; Ruiz, I; Soto, M; Bayona, J M

    2011-08-01

    The removal efficiency of 16 pharmaceuticals and personal care products (PPCPs) from urban wastewater (dissolved and particulate phases) was evaluated for the first time in a hybrid pilot plant consisting of an upflow anaerobic sludge blanket reactor followed by two sequentially connected horizontal flow constructed wetlands: a surface flow wetland (SF CW) and a subsurface flow wetland (SSF CW). Whereas the PPCP removal associated with the dissolved phase exhibited a seasonal pattern, the fraction associated with the suspended solids showed less seasonality. In the dissolved phase, the overall removal efficiency in summer ranged from 70% to 85% for salicylic acid (SAL), methyl dihydrojasmonate, caffeine (CAF), ketoprofen and triclosan, whereas in winter it declined for most of the PPCPs to between 30% and 50%, except for CAF and SAL (>80%) and carbamazepine and butylated hydroxyl toluene (11-18%). In the suspended solids, the removal exceeded 80% for most of the target PPCPs. The efficiency of the different treatment steps was also compound-dependent, but the SF CW generally exhibited the highest removal efficiency for most of the contaminants analyzed. The characterization of the organic matter retained in the wetland gravel beds revealed the occurrence of hydrophobic contaminants such as phthalate esters and fragrances at moderate concentrations (i.e., up to 3.5 μg kg(-1)), which declined strongly over the course of the different treatment steps. In the SF CW, the net mass accumulation rates of tonalide and galaxolide were 4 and 23 gy(-1) respectively, whereas in the SSF CW they were 0.3 and 1.8 gy(-1) respectively.

  7. Optimization of high-rate TN removal in a novel constructed wetland integrated with microelectrolysis system treating high-strength digestate supernatant.

    PubMed

    Guo, Luchen; He, Keli; Wu, Shubiao; Sun, Hao; Wang, Yanfei; Huang, Xu; Dong, Renjie

    2016-08-01

    The potential of high-rate TN removal in three aerated horizontal subsurface-flow constructed wetlands to treat high-strength anaerobic digestate supernatant was evaluated. Different strategies of intermittent aeration and effluent recirculation were applied to compare their effect on nitrogen depuration performance. Additional glucose supply and iron-activated carbon based post-treatment systems were established and examined, respectively, to further remove nitrate that accumulated in the effluents from aerated wetlands. The results showed that intermittent aeration (1 h on:1 h off) significantly improved nitrification with ammonium removal efficiency of 90% (18.1 g/(m(2)·d)), but limited TN removal efficiency (53%). Even though effluent recirculation (a ratio of 1:1) increased TN removal from 53% to 71%, the effluent nitrate concentration was still high. Additional glucose was used as a post-treatment option and further increased the TN removal to 82%; however, this implementation caused additional organic pollution. Furthermore, the iron-activated carbon system stimulated with a microelectrolysis process achieved greater than 85% effluent nitrate removal and resulted in 86% TN removal. Considering the high TN removal rate, aerated constructed wetlands integrated with a microelectrolysis-driven system show great potential for treating high-strength digestate supernatant. PMID:27136616

  8. Evaluation of the treatment performance and microbial communities of a combined constructed wetland used to treat industrial park wastewater.

    PubMed

    Xu, Ming; Liu, Weijing; Li, Chao; Xiao, Chun; Ding, Lili; Xu, Ke; Geng, Jinju; Ren, Hongqiang

    2016-06-01

    Constructed wetlands are ecosystems that use plants and microorganisms to remediate pollution in soil and water. In this study, two parallel pilot-scale vertical flow wetland and horizontal flow wetland (VF-HF) systems were implemented to investigate the treatment performance and microorganism community structure in the secondary effluent of an industrial park wastewater treatment plant (WWTP) with a loading rate of 100 mm/day near the Yangtze River in Suzhou City, East China. Removal efficiencies of 82.3, 69.8, 77.8, and 32.3 were achieved by the VF-HF systems for ammonium nitrogen (NH4 (+)-N), total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD), respectively. The VF system specialized in COD and NH4 (+)-N removal (73.6 and 79.2 %), whereas the HF system mainly contributed to TN removal (63.5 %). The effluents in all seasons are capable of achieving the "surface water environmental quality standard" (GB3838-2002) grade IV. In the VF system, the 16S gene and nirK gene were significantly correlated with depth, with the 16S gene showing significant correlations with the dissolved oxygen (DO) level (r = 0.954, p < 0.05), which was determined by real-time PCR and high-throughput sequencing. Many types of bacteria capable of biodegradation, including nitrifiers, denitrifiers, and polyaromatic hydrocarbon (PAH) degraders (improvement of the BOD5/COD ratio), were observed, and they contributed to approximately 90 % of the nitrogen removal in the VF-HF system. PMID:26903125

  9. Response of removal rates to various organic carbon and ammonium loads in laboratory-scale constructed wetlands treating artificial wastewater.

    PubMed

    Wu, Shubiao; Kuschk, Peter; Wiessner, Arndt; Kästner, Matthias; Pang, Changle; Dong, Renjie

    2013-01-01

    High levels (92 and 91%) of organic carbon were successfully removed from artificial wastewater by a laboratory-scale constructed wetland under inflow loads of 670 mg/m2 x d (100 mg/d) and 1600 mg/m2d (240 mg/d), respectively. Acidification to pH 3.0 was observed at the low organic carbon load, which further inhibited the denitrification process. An increase in carbon load, however, was associated with a significant elevation of pH to 6.0. In general, sulfate and nitrate reduction were relatively high, with mean levels of 87 and 90%, respectively. However, inhibition of nitrification was initiated with an increase in carbon loads. This effect was probably a result of competition for oxygen by heterotrophic bacteria and an inhibitory effect of sulfide (S2) toxicity (concentration approximately 3 mg/L). In addition, numbers of healthy stalks of Juncus effusus (common rush) decreased from 14 000 to 10 000/m2 with an increase of sulfide concentration, indicating the negative effect of sulfide toxicity on the wetland plants.

  10. Potential pathogens, antimicrobial patterns and genotypic diversity of Escherichia coli isolates in constructed wetlands treating swine wastewater.

    PubMed

    Ibekwe, A M; Murinda, Shelton E; DebRoy, Chitrita; Reddy, Gudigopura B

    2016-02-01

    Escherichia coli populations originating from swine houses through constructed wetlands were analyzed for potential pathogens, antimicrobial susceptibility patterns, and genotypic diversity. Escherichia coli isolates (n = 493) were screened for the presence of the following virulence genes: stx1, stx2 and eae (Shiga toxin-producing E. coli [STEC]), heat-labile enterotoxin (LT) genes and heat stable toxin STa and STb (enterotoxigenic E. coli (ETEC), cytotoxin necrotizing factors 1 and 2 (cnf1 and cnf2 [necrotoxigenic E. coli- NTEC]), as well as O and H antigens, and the presence of the antibiotic resistance genes blaTEM, blaSHV, blaCMY-2, tet A, tet B, tet C, mph(A), aadA, StrA/B, sul1, sul2 and sul3. The commensal strains were further screened for 16 antimicrobials and characterized by BOX AIR-1 PCR for unique genotypes. The highest antibiotic resistance prevalence was for tetracycline, followed by erythromycin, ampicillin, streptomycin, sulfisoxazole and kanamycin. Our data showed that most of the isolates had high distribution of single or multidrug-resistant (MDR) genotypes. Therefore, the occurrence of MDR E. coli in the wetland is a matter of great concern due to possible transfer of resistance genes from nonpathogenic to pathogenic strains or vice versa in the environment.

  11. Potential pathogens, antimicrobial patterns and genotypic diversity of Escherichia coli isolates in constructed wetlands treating swine wastewater.

    PubMed

    Ibekwe, A M; Murinda, Shelton E; DebRoy, Chitrita; Reddy, Gudigopura B

    2016-02-01

    Escherichia coli populations originating from swine houses through constructed wetlands were analyzed for potential pathogens, antimicrobial susceptibility patterns, and genotypic diversity. Escherichia coli isolates (n = 493) were screened for the presence of the following virulence genes: stx1, stx2 and eae (Shiga toxin-producing E. coli [STEC]), heat-labile enterotoxin (LT) genes and heat stable toxin STa and STb (enterotoxigenic E. coli (ETEC), cytotoxin necrotizing factors 1 and 2 (cnf1 and cnf2 [necrotoxigenic E. coli- NTEC]), as well as O and H antigens, and the presence of the antibiotic resistance genes blaTEM, blaSHV, blaCMY-2, tet A, tet B, tet C, mph(A), aadA, StrA/B, sul1, sul2 and sul3. The commensal strains were further screened for 16 antimicrobials and characterized by BOX AIR-1 PCR for unique genotypes. The highest antibiotic resistance prevalence was for tetracycline, followed by erythromycin, ampicillin, streptomycin, sulfisoxazole and kanamycin. Our data showed that most of the isolates had high distribution of single or multidrug-resistant (MDR) genotypes. Therefore, the occurrence of MDR E. coli in the wetland is a matter of great concern due to possible transfer of resistance genes from nonpathogenic to pathogenic strains or vice versa in the environment. PMID:26839381

  12. 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).

  13. [Development characteristics of aquatic plants in a constructed wetland for treating urban drinking water source at its initial operation stage].

    PubMed

    Zheng, Jun; Ma, Xin-Tang; Zhou, Lan; Zhou, Qing-Yuan; Wang, Zhong-Qiong; Wang, Wei-Dong; Yin, Cheng-Qing

    2011-08-01

    The development characteristics and improvement measures of aquatic plants were studied in Shijiuyang Constructed Wetland (SCW) at its initial operation stage. SCW was a large-scale wetland aiming to help relieve the source water pollution in Jiaxing City. A checklist of vascular plants in SCW was built, and species composition, life forms, biomass and association distributions were examined. Our objectives were to examine the diversity and community structure of aquatic plants in SCW at its initial operation stage, and to find out the possible hydrophyte improvement measures. The survey results showed that there were 49 vascular plant species belonging to 41 genera, 25 families in SCW, which greatly exceeded the artificially transplanted 13 species. The life forms of present aquatic plants in SCW were dominated by hygrophilous plants (20 species) and emerged plants (17 species), which accounted for 75.5% of the total number of aquatic plants. The aquatic plants transplanted artificially were dominated by emerged plants (accounted for 69.2%), while those naturally developed were predominated by hygrophilous plants (accounted for 47.2%). The horizontal distribution of aquatic plant community in SCW was mixed in the form of mosaics, which made up typical association complex. Except association Aeschynomene indica L., the dominant species of other associations were all those transplanted artificially. The naturally grown species scattered throughout the SCW and only occupied a small percentage. A marked difference was detected on the species and species richness of aquatic plants in different regions of SCW. Biomass of aquatic plant associations in SCW was 167.7 t. SCW has shown a trend of succession heading for quick increase of plant diversity at the primary operation stage. This trend provides a good material base for the future stable community of aquatic plants in SCW. According to the current status of aquatic plants, some suggestions were put forward on the

  14. Operating experience with constructed wetlands for wastewater treatment

    SciTech Connect

    Knight, R. )

    1993-01-01

    Constructed wetlands are treating a variety of municipal, industrial, and runoff wastewaters. The growing interest in this technology is based on 20 years of research demonstrating the beneficial effects of wetlands on water quality, particularly their ability to assimilate carbonaceous and nitrogenous wastes. Constructed wetlands are an attractive option for applications where a land-intensive, natural' treatment technology is desired and where ancillary wildlife benefits will enhance a project's overall environmental balance sheet. This paper summarizes design and operating experience from constructed wetlands representing a variety of applications, including pilot systems in place at several US pulp mills.

  15. Role of vegetation (Typha latifolia) on nutrient removal in a horizontal subsurface-flow constructed wetland treating UASB reactor-trickling filter effluent.

    PubMed

    da Costa, Jocilene Ferreira; Martins, Weber Luiz Pinto; Seidl, Martin; von Sperling, Marcos

    2015-01-01

    The main objective of the work is to characterize the role of plants in a constructed wetland in the removal of nitrogen (N) and phosphorus (P). The experiments were carried out in a full-scale system in the city of Belo Horizonte, Brazil, with two parallel horizontal subsurface-flow constructed wetland units (one planted with Typha latifolia and one unplanted) treating the effluent from a system composed of an upflow anaerobic sludge blanket reactor and a trickling filter (TF). Each wetland unit received a mean flow of approximately 8.5 m³ d⁻¹ (population equivalent around 60 inhabitants each), with a surface hydraulic loading rate 0.12 m³m⁻²d⁻¹. The experiments were conducted from September 2011 to July 2013. Mean effluent concentrations from the wetlands were: (a) planted unit total nitrogen (TN) 22 mg L⁻¹, ammonia-N 19 mg L⁻¹, nitrite-N 0.10 mg L⁻¹, nitrate-N 0.25 mg L⁻¹, P-total 1.31 mg L⁻¹; and (b) unplanted unit TN 24 mg L⁻¹, ammonia-N 20 mg L⁻¹, nitrite-N 0.54 mg mL⁻¹, nitrate-N 0.15 mg L⁻¹, P-total 1.31 mg L⁻¹. The aerial part of the plant contained mean values of 24.1 gN (kg dry matter)⁻¹ and 4.4 gP (kg dry matter)⁻¹, and the plant root zone was composed of 16.5 gN (kg dry matter)⁻¹ and 4.1 gP (kg dry matter)⁻¹. The mean extraction of N by the plant biomass was 726 kgN ha⁻¹y⁻¹, corresponding to 17% of the N load removed. For P, the extraction by the plant biomass was 105 kgP ha⁻¹y⁻¹, corresponding to 9% of the P load removed. These results reinforce the reports that N and P removal due to plant uptake is a minor mechanism in horizontal subsurface-flow constructed wetlands operating under similar loading rates, typical for polishing of sanitary effluent. PMID:25860702

  16. The effect of aeration and recirculation on a sand-based hybrid constructed wetland treating low-strength domestic wastewater.

    PubMed

    Zapater-Pereyra, M; Kyomukama, E; Namakula, V; van Bruggen, J J A; Lens, P N L

    2016-08-01

    The Duplex-constructed wetland (CW) is a hybrid system composed of a vertical flow (VF) CW on top of a horizontal flow filter (HFF). Each compartment is designed to play a different role: aerobic treatment in the VF CW due to intermittent feeding and anoxic treatment in the HFF due to saturated conditions. Three Duplex-CWs were used in this study: Control, Aerated and Recirculating. The role of each compartment was tested for pollutant removal and micro-invertebrate abundance. In all systems, the VF CW removed mainly organic matter, solids and NH4(+)-N. Pathogens were removed in both compartments. Likewise, total nitrogen removal occurred in both compartments, only the Recirculating HFF was not able to denitrify the nitrogen due to the slightly more oxic conditions as compared to the other systems. All systems met discharge guidelines for organic matter, but only the Control and Aerated systems met those for total nitrogen. At the applied loading rates, the pollutant removal was not significantly enhanced by the use of aeration and recirculation. Therefore, operation as in the Control system, without aeration or recirculation, is recommended for the tested Duplex-CWs. If artificial aeration will be used in CWs, the support material should be carefully selected to allow a proper air distribution. PMID:26732367

  17. The effect of aeration and recirculation on a sand-based hybrid constructed wetland treating low-strength domestic wastewater.

    PubMed

    Zapater-Pereyra, M; Kyomukama, E; Namakula, V; van Bruggen, J J A; Lens, P N L

    2016-08-01

    The Duplex-constructed wetland (CW) is a hybrid system composed of a vertical flow (VF) CW on top of a horizontal flow filter (HFF). Each compartment is designed to play a different role: aerobic treatment in the VF CW due to intermittent feeding and anoxic treatment in the HFF due to saturated conditions. Three Duplex-CWs were used in this study: Control, Aerated and Recirculating. The role of each compartment was tested for pollutant removal and micro-invertebrate abundance. In all systems, the VF CW removed mainly organic matter, solids and NH4(+)-N. Pathogens were removed in both compartments. Likewise, total nitrogen removal occurred in both compartments, only the Recirculating HFF was not able to denitrify the nitrogen due to the slightly more oxic conditions as compared to the other systems. All systems met discharge guidelines for organic matter, but only the Control and Aerated systems met those for total nitrogen. At the applied loading rates, the pollutant removal was not significantly enhanced by the use of aeration and recirculation. Therefore, operation as in the Control system, without aeration or recirculation, is recommended for the tested Duplex-CWs. If artificial aeration will be used in CWs, the support material should be carefully selected to allow a proper air distribution.

  18. Effects of cattail biomass on sulfate removal and carbon sources competition in subsurface-flow constructed wetlands treating secondary effluent.

    PubMed

    Chen, Yi; Wen, Yue; Zhou, Junwei; Tang, Zhiru; Li, Ling; Zhou, Qi; Vymazal, Jan

    2014-08-01

    Sulfate is frequently found in the influent of subsurface-flow constructed wetlands (SSF CWs) used as tertiary treatments. To reveal the effects of plants and litters on sulfate removal, as well as the competition for organic carbon among microorganisms in SSF CWs, five laboratory-scale SSF CW microcosms were set up and were operated as a batch system with HRT 5 d. The results showed that the presence of Typha latifolia had little effect on sulfate removal in CWs, with or without additional carbon sources. Cattail litter addition greatly improved sulfate removal in SSF CWs. This improvement was linked to the continuous input of labile organic carbon, which lowers the redox level and supplies a habitat for sulfate reducing bacteria (SRB). The presence of SRB in cattail litter indicated the possibility of sulfate removal around the carbon supplier, but the quantity of microbes in cattail litter was much lower than that in gravel. Stoichiometry calculations showed that the contribution of SRB to COD removal (21-26%) was less than that of methane-producing bacteria (MPB) (47-61%) during the initial stage but dominated COD removal (42-65%) during the terminal stage. The contributions of aerobic bacteria (AB) and denitrification bacteria (DB) to COD removal were always lower than that of SRB. It was also observed that the variations in COD: S ratio had a great influence on the relative abundance of genes between SRB and MPB and both of them could be used as good predictors of carbon competition between SRB and MPB in CWs.

  19. [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.

  20. Validity of manganese as a surrogate of heavy metals removal in constructed wetlands treating acidic mine water

    SciTech Connect

    Royer, E.; Unz, R.F.; Hellier, W.W.

    1998-12-31

    The evaluation of manganese as a surrogate for heavy metal behavior in two wetland treatment systems receiving acidic coal mine drainage in central Pennsylvania was investigated. The use of manganese as an indicator is based on physical/chemical treatment processes quite different from wetland treatment. The treatment systems represented one anoxic, subsurface flow system and one oxic surface flow system. Water quality parameters measured included pH, alkalinity, acidity, and a suite of metals. Correlation and linear regression analysis were used to evaluate the ability of a candidate predictor variable (indicator) to predict heavy metal concentrations and removal. The use of manganese as a predictor of effluent quality proved to be poor in both wetland treatment systems, as evidenced by low linear R{sup 2} values and negative correlations. Zinc emerged as the best predictor of the detectable heavy metals at the anoxic wetland. Zinc exhibited positive strong linear correlations with copper, cobalt, and nickel (R{sup 2} values of 0.843, 0.881, and 0.970, respectively). Effluent pH was a slightly better predictor of effluent copper levels in the anoxic wetland. Iron and cobalt effluent concentrations showed the only strong relationship (R{sup 2} value = 0.778) in the oxic system. The lack of good correlations with manganese strongly challenges its appropriateness as a surrogate for heavy metals in these systems.

  1. Long-term nitrogen compound removal trends of a hybrid subsurface constructed wetland treating milking parlor wastewater throughout its 7 years of operation.

    PubMed

    Harada, J; Inoue, T; Kato, K; Izumoto, H; Zhang, X; Sakuragi, H; Wu, D; Ietsugu, H; Sugawara, Y

    2016-01-01

    This study evaluated the nitrogen compound removal efficiency of a hybrid subsurface constructed wetland, which began treating milking parlor wastewater in Hokkaido, northern Japan, in 2006. The wetland's overall removal rates of total nitrogen (TN) and ammonium (NH4(+)-N) improved after the second year of operation, and its rate of organic nitrogen (Org-N) removal was stable at 90% efficiency. Only nitrate (NO3(-)-N) levels were increased following the treatment. Despite increased NO3(-)-N (maximum of 3 mg-N/L) levels, TN removal rates were only slightly affected. Removal rates of TN and Org-N were highest in the first vertical bed. NH4(+)-N removal rates were highest in the second vertical bed, presumably due to water recirculation and pH adjustment. Concentrations of NO3(-)-N appeared when total carbon (TC) levels were low, which suggests that low TC prevented complete denitrification in the second vertical bed and the final horizontal bed. In practice, the beds removed more nitrogen than the amount theoretically removed by denitrification, as calculated by the amount of carbon removed from the system. This carbon-nitrogen imbalance may be due to other nitrogen transformation mechanisms, which require less carbon.

  2. Long-term nitrogen compound removal trends of a hybrid subsurface constructed wetland treating milking parlor wastewater throughout its 7 years of operation.

    PubMed

    Harada, J; Inoue, T; Kato, K; Izumoto, H; Zhang, X; Sakuragi, H; Wu, D; Ietsugu, H; Sugawara, Y

    2016-01-01

    This study evaluated the nitrogen compound removal efficiency of a hybrid subsurface constructed wetland, which began treating milking parlor wastewater in Hokkaido, northern Japan, in 2006. The wetland's overall removal rates of total nitrogen (TN) and ammonium (NH4(+)-N) improved after the second year of operation, and its rate of organic nitrogen (Org-N) removal was stable at 90% efficiency. Only nitrate (NO3(-)-N) levels were increased following the treatment. Despite increased NO3(-)-N (maximum of 3 mg-N/L) levels, TN removal rates were only slightly affected. Removal rates of TN and Org-N were highest in the first vertical bed. NH4(+)-N removal rates were highest in the second vertical bed, presumably due to water recirculation and pH adjustment. Concentrations of NO3(-)-N appeared when total carbon (TC) levels were low, which suggests that low TC prevented complete denitrification in the second vertical bed and the final horizontal bed. In practice, the beds removed more nitrogen than the amount theoretically removed by denitrification, as calculated by the amount of carbon removed from the system. This carbon-nitrogen imbalance may be due to other nitrogen transformation mechanisms, which require less carbon. PMID:26942522

  3. 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

  4. 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.

  5. 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

  6. Process-Based Modeling of Constructed Wetlands

    NASA Astrophysics Data System (ADS)

    Baechler, S.; Brovelli, A.; Rossi, L.; Barry, D. A.

    2007-12-01

    Constructed wetlands (CWs) are widespread facilities for wastewater treatment. In subsurface flow wetlands, contaminated wastewater flows through a porous matrix, where oxidation and detoxification phenomena occur. Despite the large number of working CWs, system design and optimization are still mainly based upon empirical equations or simplified first-order kinetics. This results from an incomplete understanding of the system functioning, and may in turn hinder the performance and effectiveness of the treatment process. As a result, CWs are often considered not suitable to meet high water quality-standards, or to treat water contaminated with recalcitrant anthropogenic contaminants. To date, only a limited number of detailed numerical models have been developed and successfully applied to simulate constructed wetland behavior. Among these, one of the most complete and powerful is CW2D, which is based on Hydrus2D. The aim of this work is to develop a comprehensive simulator tailored to model the functioning of horizontal flow constructed wetlands and in turn provide a reliable design and optimization tool. The model is based upon PHWAT, a general reactive transport code for saturated flow. PHWAT couples MODFLOW, MT3DMS and PHREEQC-2 using an operator-splitting approach. The use of PHREEQC to simulate reactions allows great flexibility in simulating biogeochemical processes. The biogeochemical reaction network is similar to that of CW2D, and is based on the Activated Sludge Model (ASM). Kinetic oxidation of carbon sources and nutrient transformations (nitrogen and phosphorous primarily) are modeled via Monod-type kinetic equations. Oxygen dissolution is accounted for via a first-order mass-transfer equation. While the ASM model only includes a limited number of kinetic equations, the new simulator permits incorporation of an unlimited number of both kinetic and equilibrium reactions. Changes in pH, redox potential and surface reactions can be easily incorporated

  7. Effect of operational and design parameters on performance of pilot-scale horizontal subsurface flow constructed wetlands treating university campus wastewater.

    PubMed

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

    2016-10-01

    Three horizontal subsurface flow (HSF) pilot-scale constructed wetland (CW) units operated for 3 years treating municipal wastewater originating from a university campus. The main objective of the study was the evaluation of the performance of these systems under several operational, design, and climatic conditions. Several parameters and factors were investigated, including the influence of temperature, vegetation, and hydraulic residence time. The results were compared to those of a previous study conducted in the same pilot-scale units and under the same operational conditions where synthetic municipal wastewater was used. Results show the satisfying overall performance of the CW units. Performance seems to be influenced by vegetation, temperature, and hydraulic residence time (HRT). The planted units produced better results than the unplanted one while, generally, all units operated better under warmer conditions. In addition, longer HRTs contributed to higher removal efficiencies. Finally, the systems showed higher removal efficiencies in the previous study (synthetic wastewater) regarding organic matter removal, while for the other pollutants, the present study (real wastewater) showed higher or comparable performance in most cases and especially in the planted units. The study also shows the overall good, continuous, and long-term operation of CW systems, since these systems operate for about 13 years. PMID:27388592

  8. Effect of operational and design parameters on performance of pilot-scale horizontal subsurface flow constructed wetlands treating university campus wastewater.

    PubMed

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

    2016-10-01

    Three horizontal subsurface flow (HSF) pilot-scale constructed wetland (CW) units operated for 3 years treating municipal wastewater originating from a university campus. The main objective of the study was the evaluation of the performance of these systems under several operational, design, and climatic conditions. Several parameters and factors were investigated, including the influence of temperature, vegetation, and hydraulic residence time. The results were compared to those of a previous study conducted in the same pilot-scale units and under the same operational conditions where synthetic municipal wastewater was used. Results show the satisfying overall performance of the CW units. Performance seems to be influenced by vegetation, temperature, and hydraulic residence time (HRT). The planted units produced better results than the unplanted one while, generally, all units operated better under warmer conditions. In addition, longer HRTs contributed to higher removal efficiencies. Finally, the systems showed higher removal efficiencies in the previous study (synthetic wastewater) regarding organic matter removal, while for the other pollutants, the present study (real wastewater) showed higher or comparable performance in most cases and especially in the planted units. The study also shows the overall good, continuous, and long-term operation of CW systems, since these systems operate for about 13 years.

  9. Design and configuration criteria for wetland systems treating greywater.

    PubMed

    Paulo, P L; Begosso, L; Pansonato, N; Shrestha, Roshan R; Boncz, M A

    2009-01-01

    Design and configuration for wetlands treating greywater are usually based on literature data obtained from domestic wastewater operating wetlands. It is very important to determine proper criteria for design and configuration to provide efficiency and minimum maintenance, avoiding bad odour and clogging amongst others, ensuring the acceptance of householders. The aim of this work was to design a wetland system treating greywater for a household and determine whether the chosen criteria were appropriate. Some of the criteria taken into consideration for design and configuration were: quantitative and qualitative characteristics, desired removal of biochemical oxygen demand (BOD) and suspended solids (TSS), substrate and ornamental aspect of the system. The system was composed of a grease trap (kitchen), sedimentation tank, a horizontal flow constructed wetland (HF-CW), intermittent feeding system, and a vertical flow constructed wetland (VF-CW). The results showed that the suggested design and configuration were in accordance with the expected efficiency. Being a compact system, it was susceptible to peak flows, temporarily deteriorating the performance of the HF-CW. The hybrid system, however, showed to cope well with influent fluctuations. The overall performance of the system shows that the removal of turbidity, TSS, COD and BOD were over 88%, reaching 95% removal for both BOD and turbidity. PMID:19844046

  10. Design and configuration criteria for wetland systems treating greywater.

    PubMed

    Paulo, P L; Begosso, L; Pansonato, N; Shrestha, Roshan R; Boncz, M A

    2009-01-01

    Design and configuration for wetlands treating greywater are usually based on literature data obtained from domestic wastewater operating wetlands. It is very important to determine proper criteria for design and configuration to provide efficiency and minimum maintenance, avoiding bad odour and clogging amongst others, ensuring the acceptance of householders. The aim of this work was to design a wetland system treating greywater for a household and determine whether the chosen criteria were appropriate. Some of the criteria taken into consideration for design and configuration were: quantitative and qualitative characteristics, desired removal of biochemical oxygen demand (BOD) and suspended solids (TSS), substrate and ornamental aspect of the system. The system was composed of a grease trap (kitchen), sedimentation tank, a horizontal flow constructed wetland (HF-CW), intermittent feeding system, and a vertical flow constructed wetland (VF-CW). The results showed that the suggested design and configuration were in accordance with the expected efficiency. Being a compact system, it was susceptible to peak flows, temporarily deteriorating the performance of the HF-CW. The hybrid system, however, showed to cope well with influent fluctuations. The overall performance of the system shows that the removal of turbidity, TSS, COD and BOD were over 88%, reaching 95% removal for both BOD and turbidity.

  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. Modeling BOD removal in constructed wetlands with mixing cell method

    SciTech Connect

    Chen, S.; Wang, G.T.; Xue, S.K.

    1999-01-01

    A new concept, transport detention time, is proposed in this paper to describe solute-transport processes. Using this concept, a new mathematical model was developed to describe biochemical oxygen demand removal in constructed wetlands. By treating a constructed wetland as a series of continuous stir tank reactors, an nth-order ordinary differential equation was derived based on the principle of mass balance and convective-dispersive equation and by introducing transfer function and Laplace transform. The number of continuous stir tank reactors of a particular wetland was determined by the parameters, such as dispersion coefficient and flow velocity, occurring in the wetland. Two examples were presented to illustrate the applications of the model. Moment method and a combination of moment and optimization methods were used to estimate the model parameters from tracer experiment data. A comparison between the model presented in this paper and the currently used plug-flow-constructed wetland model indicated that the former was more accurate. Additionally, this model can be applied to transient conditions, is theoretically sound, and represents a theoretical advance in constructed wetland research.

  13. The dynamics of low-chlorinated benzenes in a pilot-scale constructed wetland and a hydroponic plant root mat treating sulfate-rich groundwater.

    PubMed

    Chen, Zhongbing; Kuschk, Peter; Paschke, Heidrun; Kästner, Matthias; Köser, Heinz

    2015-03-01

    A rarely used hydroponic plant root mat filter (PRMF, of 6 m(2)) and a horizontal subsurface flow constructed wetland (HSSF CW, of 6 m(2)), operating in continuous flow and discontinuous outflow flushing modes, were investigated for treating sulfate-rich and organic carbon-lean groundwater contaminated with monochlorobenzene (MCB); 1,2-dichlorobenzene (1,2-DCB); 1,4-dichlorobenzene (1,4-DCB); and 2-chlorotoluene. Whereas the mean inflow loads ranged from 1 to 247 mg m(-2) days(-1), the range of mean inflow concentrations of the chlorobenzenes recorded over a period of 7 months was within 0.04 and 8 mg L(-1). A hydraulic surface loading rate of 30 L m(-2) days(-1) was obtained in both systems. The mean load removal efficiencies were found to vary between 87 and 93 % in the PRMF after a flow path of 4 m, while the removal efficiencies were found to range between 46 and 70 % and 71 to 73 % in the HSSF CW operating in a continuous flow mode and a discontinuous outflow flushing mode, respectively. Seasonal variations in the removal efficiencies were observed for all low-chlorinated hydrocarbons both in the PRMF and the HSSF CW, whereby the highest removal efficiencies were reached during the summer months. Sulfide formation occurred in the organic carbon-lean groundwater particularly in summer, which is probably due to the plant-derived organic carbon that fostered the microbial dissimilatory sulfate reduction. Higher redox potential in water was observed in the PRMF. In conclusion, the PRMF could be an option for the treatment of water contaminated with compounds which in particular need oxic conditions for their microbial degradation, such as in the case of low-chlorinated benzenes.

  14. Constructed wetland treatment systems for the remediation of metal- bearing aqueous discharges. Final report

    SciTech Connect

    Woodis, A.L.

    1995-08-01

    Electric utility activities, such as coal mining, processing, and combustion, often produce aqueous (wastewater) discharges containing metals. Chemical treatment of these discharges to achieve compliance with National Pollution Discharge Elimination System (NPDES) requirements can be costly. Constructed wetland treatment systems offer an inexpensive, natural, low-maintenance, and potentially long-term solution for the treatment of aqueous discharges without chemical additives. At the present time, several electric utilities are using constructed wetland treatment systems to achieve NPDES compliance. Constructed wetland treatment systems take advantage of natural biogeochemical processes to treat utility wastewaters, thus meeting NPDES compliance levels in an environmentally effective manner. This report provides information on the natural science, wastewater treatment, and regulatory/jurisdictional aspects of constructed wetland treatment systems used within the electric utility industry. Included is data from a number of electric utility constructed wetland treatment sites. The principal advantages of using constructed wetland systems to treat wastewater are the low overall cost compared to more conventional chemical treatment methods, the simplicity of operation, and the capacity to provide long-term resource recovery. For example, using a lined constructed wetland treatment system with high retention efficiency for heavy metals provides the option of resource recovery at some future date from a discrete volume of wetland material. Contaminants that can be removed with high efficiency in a number of constructed wetland treatment systems include heavy metals, toxic organics, suspended solids, and nutrients. This report discusses the treatability of specific contaminants as well as metal uptake and translocation processes in constructed wetlands.

  15. Evaluating the efficiency of toxicity abatement in a constructed wetland with Ceriodaphnia dubia.

    PubMed

    Belin, J I; McCaskey, T A; Black, M C

    2000-05-26

    Constructed wetlands are becoming increasingly popular as low-cost, high-efficiency means of treating agricultural and municipal wastewaters. Monitoring programs for constructed wetlands usually measure physical and chemical characteristics of wetland treatment, including hydraulic residence time and removal of nutrients (N, P), suspended solids, and biochemical oxygen demand (BOD). However, toxicity abatement is seldom measured as evidence of wetland treatment efficiency. In this study, toxicity tests combined with chemical measurements were employed to measure the efficiency of a constructed wetland in treating swine wastes during fall and winter sampling periods. Although the wetland system operated at three wastewater loading rates, only the high-loading-rate cells were tested because of their year-round flows. Wastewater samples were collected prior to, during, and following wetland treatment to track treatment progress as effluents passed through the wetland cells. Toxicity tests with Ceriodaphnia dubia showed significant toxicity abatement of wastewater as it progressed through the constructed wetland system; however, residual toxicity was still observed in the final wetland effluent. No seasonal differences were observed in toxicity abatement between fall and winter wastewater samples, although nitrate and BOD were removed more efficiently during the fall. Results suggest that, while the constructed wetland system is effective in reducing toxicity in swine wastewater, further pre- or posttreatment or additional dilution is necessary before treated effluents are discharged into surface water.

  16. 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.

  17. 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. PMID:20034652

  18. 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 ...

  19. Monitoring manganese diagenesis in a constructed wetland using continuous gradient gels

    SciTech Connect

    Edenborn, H.M.; Brickett, L.A.; Dvorak, D.H. . Pittsburgh Research Center); Edenborn, S.L. . Dept. of Biology)

    1992-01-01

    Constructed wetlands are used by coal mining companies to lower concentrations of dissolved Fe and Mn and reduce the cost of treating mine drainage chemically. Biological activity in wetlands assists in the removal of these metals by mediating their oxidation and reduction, and the intensity of these reactions is influenced strongly by seasonal fluctuations in wetlands have been developed empirically based on field observations, but few details are known about the spatial and temporal variation in Mn diagenesis within these wetlands. Biological activity within wetland sediments is known to be very heterogeneous, due in part to the complex composition of the composted organic materials used in wetland construction. This heterogeneity makes it difficult to assess the importance of specific diagenetic processes without taking large numbers of samples at great expense. In this study, continuous gradient gels (CGGs) were used to evaluate metal diagenesis spatially and seasonally within the sediments of a constructed wetland in northwestern PA receiving coal mine drainage. The CGGs were inexpensive to construct and were easy to deploy in the field. CGGs provided rapid and detailed information in the regions of stability of Mn oxides within the wetland sediment. The resulting data were mapped and used to assess the overall efficiency of constructed wetland design and the impact of Mn diagenesis in wetlands used to treat coal mine drainage.

  20. Constructed wetland design: The first generation

    SciTech Connect

    Reed, S.C.; Brown, D.S.

    1992-01-01

    A recent inventory, sponsored by the U.S. EPA Risk Reduction Engineering Laboratory in Cincinnati, OH documented the presence of over 150 constructed wetlands systems in the U.S., for the treatment of municipal and industrial wastewaters. The total flow received by these systems is about 400,000 cu m/d (100 mgd). This paper summarizes some of the results from the inventory, including: location, type, vegetation, design flow, loading rates, and costs for wetland systems where this information was available. The paper also discusses some 'lessons learned' from site visits to several of the systems.

  1. 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.

  2. 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

  3. 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. PMID:22567700

  4. 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.

  5. Performance and behaviour of planted and unplanted units of a horizontal subsurface flow constructed wetland system treating municipal effluent from a UASB reactor.

    PubMed

    da Costa, Jocilene Ferreira; de Paoli, André Cordeiro; Seidl, Martin; von Sperling, Marcos

    2013-01-01

    A system composed of two horizontal subsurface flow constructed wetlands operating in parallel was evaluated for the post-treatment of UASB (upflow anaerobic sludge blanket) reactor effluent, for a population equivalent of 50 inhabitants per unit. One unit was planted with cattail (Typha latifolia) and the other was unplanted. The study was undertaken over a period of 4 years, comprising monitoring of influent and effluent constituents together with a full characterization of the behaviour of the units (tracer studies, mathematical modelling of chemical oxygen demand (COD) decay, characterization of solids in the filter medium). The mean value of the surface hydraulic load was 0.11 m(3)m(-2)d(-1), and the theoretical hydraulic retention time was 1.1 d in each unit. Using tracer tests with (82)Br, dispersion number (d) values of 0.084 and 0.079 for the planted and unplanted units were obtained, indicating low to moderate dispersion. The final effluent had excellent quality in terms of organic matter and suspended solids, but the system showed low capacity for nitrogen removal. Four-year mean effluent concentration values from the planted and unplanted units were, respectively: biochemical oxygen demand (BOD(5)): 25 and 23 mg L(-1); COD: 50 and 55 mg L(-1); total suspended solids (TSS): 9 and 9 mg L(-1); N-ammonia: 27 and 28 mg L(-1). The COD decay coefficient K for the traditional plug-flow model was 0.81 and 0.84 d(-1) for the planted and unplanted units. Around 80% of the total solids present in the filter medium were inorganic, and most of them were present in the interstices rather than attached to the support medium. As an overall conclusion, horizontal subsurface flow wetlands can be a very suitable post-treatment method for municipal effluents from anaerobic reactors.

  6. High performance constructed wetlands for cold climates.

    PubMed

    Jenssen, Petter D; Maehlum, Trend; Krogstad, Tore; Vråle, Lasse

    2005-01-01

    In 1991, the first subsurface flow constructed wetland for treatment of domestic wastewater was built in Norway. Today, this method is rapidly becoming a popular method for wastewater treatment in rural Norway. This is due to excellent performance even during winter and low maintenance. The systems can be constructed regardless of site conditions. The Norwegian concept for small constructed wetlands is based on the use of a septic tank followed by an aerobic vertical down-flow biofilter succeeded by a subsurface horizontal-flow constructed wetland. The aerobic biofilter, prior to the subsurface flow stage, is essential to remove BOD and achieve nitrification in a climate where the plants are dormant during the cold season. When designed according to present guidelines a consistent P-removal of > 90% can be expected for 15 years using natural iron or calcium rich sand or a new manufactured lightweight aggregate with P-sorption capacities, which exceeds most natural media. When the media is saturated with P it can be used as soil conditioner and P-fertilizer. Nitrogen removal in the range of 40-60% is achieved. Removal of indicator bacteria is high and < 1000 thermotolerant coliforms/100 ml is normally achieved.

  7. 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...

  8. CONSTRUCTED WETLANDS FOR TREATMENT OF HEAVY METALS IN URBAN STORMWATER RUNOFF: CHEMICAL SPECIATION OF WETLAND SEDIMENTS

    EPA Science Inventory

    Heavy metals in urban stormwater runoff are primarily removed by sedimentation in stormwater best management practices (BMPs) such as constructed wetlands. Heavy metals accumulated in wetland sediments may be potentially toxic to benthic invertebrates and aquatic microorganisms, ...

  9. 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

  10. 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.

  11. Emergy evaluations for constructed wetland and conventional wastewater treatments

    NASA Astrophysics Data System (ADS)

    Zhou, J. B.; Jiang, M. M.; Chen, B.; Chen, G. Q.

    2009-04-01

    Based on emergy synthesis, this study presents a comparative study on constructed wetland (CW) and conventional wastewater treatments with three representative cases in Beijing. Accounting the environmental and economic inputs and treated wastewater output based on emergy, different characteristics of two kinds of wastewater treatments are revealed. The results show that CWs are environment-benign, less energy-intensive despite the relatively low ecological waste removal efficiency (EWRE), and less cost in construction, operation and maintenance compared with the conventional wastewater treatment plants. In addition, manifested by the emergy analysis, the cyclic activated sludge system (CASS) has the merit of higher ecological waste elimination efficiency.

  12. Constructed wetlands for the treatment of landfill leachate

    SciTech Connect

    Mulamoottil, G.; McBean, E.; Rovers, F.

    1998-12-31

    The book addresses leachate characteristics and the potential for treatability by constructed wetlands, the assessment of tolerance of wetland plants to the toxicity of leachates in differing climates, the role of plants in treatment of leachates, cost comparisons using wetland technology vs. traditional treatment and more.

  13. 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

  14. Hexachlorobenzene dechlorination in constructed wetland mesocosms.

    PubMed

    Zhou, Yuanqing; Tigane, Triin; Li, Xiuzhen; Truu, Marika; Truu, Jaak; Mander, Ulo

    2013-01-01

    We studied the dechlorination of hexachlorobenzene (HCB) in wetland mesocosm (MC) trials filled with sediment (well mineralized homogenized peat mixed with mud) from a wastewater treatment wetland located in a floodplain: three MCs were planted with common reed (Phragmites australis) and another three with broad-leaved cattail (Typha latifolia). According to the rootzone development we distinguished between the upper (0-10 cm from the soil surface) and lower layers (20-30 cm). Over 36 days, the initial measured concentration of HCB was reduced to 61%, 51%, 42% and 40% in the lower layer without roots of Phragmites, in the lower layer with roots of Typha, in the upper layer with roots of Typha, and in the upper layer with roots of Phragmites respectively. The 90% degradation time (DT(90)) of the initial measured HCB can be calculated as 192, 121, 110 and 92 days (d) respectively. PeCB, 1, 2, 3, 4-, 1, 2, 3, 5- and 1, 2, 4, 5-TeCB, and 1, 2, 3-, 1, 2, 4- and 1, 3, 5-TCB were the main dechlorination products detected in MC sediment samples. The dechlorination rates of HCB were higher in sediment layers with well-developed root zones. According to the DT(50) of 28-58 days and DT(90) of 92-192 days, HCB can be considered to be a less persistent organic pollutant in constructed wetlands.

  15. Exploring fecal indicator bacteria in a constructed stormwater wetland.

    PubMed

    Hathaway, J M; Hunt, W F; Graves, A K; Bass, K L; Caldwell, A

    2011-01-01

    Microbial pollution in surface waters is a concern throughout the world, with both public health and economic implications. One contributing source to such pollution is stormwater runoff, often treated using various types of stormwater control measures. However, relatively little is known regarding microbe sequestration in constructed stormwater wetlands (CSWs), one type of commonly installed stormwater control measure. In this study, indicator bacteria concentrations in both the water and sediment of a CSW were evaluated at multiple locations. Results suggested that fecal coliform concentrations in stormwater runoff decrease through the system, with relatively consistent concentrations noted throughout the second half of the wetland. This potentially indicates a baseline concentration of fecal coliform is present due to internal processes such as animal activity and microbial persistence. However, wetland sediments showed little E. coli present during most sampling events, with minimal patterns existing with respect to sediment sampling location. CSW designs should promote optimization of hydraulic retention time and minimization of stormwater velocities to promote sedimentation and degradation of microbes by way of wetland treatment functions.

  16. Kinetic and empirical design criteria for constructed wetlands

    SciTech Connect

    Nix, P.G.; Gulley, J.R.

    1995-12-31

    Design criteria were derived for estimating the size of constructed wetlands needed to treat oil sands mining wastewater using a field-scale wetland experimental facility in northeastern Alberta, Canada. The objective of this research was to demonstrate the capabilities of such wetlands as long-term, self-sustaining ``natural`` systems for the treatment of large quantities of wastewater anticipated to be released from tailings ponds after mine abandonment. Using empirical data (i.e., hydrocarbon loading rates versus effluent quality), the optimal range of hydrocarbon loading was 5 to 25 gTEH/m{sup 2}/month. Using more conservative kinetic data (i.e., microbial mineralization rates), the range of optimal treatment effectiveness was 9.6 to 13.2 gTEH/m{sup 2}/month. Since these two design criteria methodologies were calculated using two independent analytical methods, the similarity in results represents a substantial validation of their accuracy. Further research is being undertaken to confirm these findings, to improve treatment performance, and to assess the ecological characteristics of these wetlands.

  17. 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.

  18. Constructed wetlands for water pollution management of aquaculture farms conducting earthen pond culture.

    PubMed

    Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan; Chang, Yih-Feng; Sui, Hsuan-Yu

    2010-08-01

    This study established farm-scale constructed wetlands integrated to shrimp ponds, using existing earthern pond areas, with a wetland-to-pond ratio of only 0.086 for shrimp culture. The constructed wetlands were used as practice for aquaculture water and wastewater treatment, to regulate the water quality of shrimp ponds and manage pollution from pond effluents. The results of water quality monitoring for influent and effluent showed that constructed wetlands significantly reduced total suspended solids (59 to 72%), turbidity (55 to 65%), chlorophyll a (58 to 72%), 5-day biochemical oxygen demand (29 to 40%), and chemical oxygen demand (13 to 24%) from pond water. The wetland treatment sufficiently regulated water quality of the recirculating shrimp pond, which was significantly (p < 0.05) better than that in a control shrimp pond, without the connection of constructed wetlands. Furthermore, the wetland-treated effluent satisfied the national effluent standards for aquaculture farms (R.O.C. Environmental Protection Administration, 2007). Accordingly, wetland treatment applications were proposed to implement the best management practices to reduce pollution from aquaculture farms in Taiwan.

  19. 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.

  20. Possible use of constructed wetland to remove selenocyanate, arsenic, and boron from electric utility wastewater.

    PubMed

    Ye, Z H; Lin, Z-Q; Whiting, S N; de Souza, M P; Terry, N

    2003-09-01

    Wetland microcosms were used to evaluate the ability of constructed wetlands to remove extremely high concentrations of selenocyanate (SeCN-), arsenic (As), and boron (B) from wastewater generated by a coal gasification plant in Indiana. The wetland microcosms significantly reduced the concentrations of selenium (Se), As, B, and cyanide (CN) in the wastewater by 64%, 47%, 31%, and 30%, respectively. In terms of the mass of each contaminant, 79%, 67%, 57%, and 54% of the Se, As, B, and CN, respectively, loaded into the microcosms were removed from the wastewater. The primary sink for the retention of contaminants within the microcosms was the sediment, which accounted for 63%, 51%, and 36% of the Se, As, and B, respectively. Accumulation in plant tissues accounted for only 2-4%, while 3% of the Se was removed by biological volatilization to the atmosphere. Of the 14 plant species tested, cattail, Thalia, and rabbitfoot grass were highly tolerant of the contaminants and exhibited no growth retardation. Environmental toxicity testing with fathead minnow (Pimephales promelas) larvae confirmed that the water treated by the wetland microcosms was less toxic than untreated water. The data from the wetland microcosms support the view that constructed wetlands could be used to successfully reduce the toxicity of aqueous effluent contaminated with extremely high concentrations of SeCN-, As, and B, and that a pilot-scale wetland should therefore be constructed to test this in the field. Cattail, Thalia, and rabbitfoot grass would be suitable plant species to establish in such wetlands.

  1. 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.

  2. 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.

  3. Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems.

    PubMed

    Yang, L; Hu, C C

    2005-01-01

    In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.

  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. Phytoremediation of explosive contaminated groundwater in constructed wetlands: I - batch study

    SciTech Connect

    Sikora, F.J.; Berends, L.L.; Phillips, W.D.; Kelly, D.A.; Coonrod, H.S.

    1995-06-01

    The study evaluates the utility of constructed wetlands for remediating constructed wetlands using bench scale wetlands (batch type). Specifically the study examines: the degradation of TNT and RDX in contaminated waters in a variety of wetland types; the impact of wetland type on chemical oxygen demand; and tracks the level of degradation products in various wetland types. The study also provides design recommendations for the wetlands demonstration project to be located at the Milan Army Ammunition Plant (MAAP), in Tennessee.

  6. 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.

  7. In situ biodegradation of perchloroethylene in constructed wetland mesocosms

    SciTech Connect

    Hoylman, A.M.; Rosensteel, B.A.; Trettin, C.C.

    1994-12-31

    Anaerobic reductive dehalogenation initiates degradation of highly chlorinated organic compounds. Subsequent intermediate chlorinated compounds are in turn more readily degraded in aerobic environments. Thus, complete degradation of chlorinated compounds to nontoxic end products requires both anaerobic and aerobic environments. These environments are provided by constructed wetland bioremediation systems, which through the interaction of vegetation, microbial, chemical, and physical processes, result in waste water renovation. The authors integrated the ecological engineering technology of constructed wetland systems with developments in plant-rhizosphere degradation of organic contaminants to examine the effectiveness of constructed wetland systems for in situ bioremediation of waste water contaminated with a chlorinated hydrocarbon, perchloroethylene (PCE) and an aromatic hydrocarbon, toluene. A mesocosm was designed to provide sequential anaerobic and vegetated-aerobic cells with complete control of water and gas flux and to emulate wetland properties such as hydric soil composition, physicochemical parameters, and the presence of wetland vegetation (Eleocharis acicularis). Treatments included contaminated and non-contaminated wetland cells and sterile controls. The fate and transport of PCE, toluene, and metabolic by-products were determined in effluent and chamber headspace, and extracts of soil and plant tissue. These analyses provide the basis for evaluating contaminant fate in wetland systems. Manipulation of aeration and hydrologic regimes in the wetland cells will facilitate testing conditions that affect degradation processes. The experimental apparatus is a innovative design for experimentation on the degradation of volatile organic compounds in plant-soil systems.

  8. 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

  9. Constructed wetlands for wastewater treatment: Municipal, industrial and agricultural

    SciTech Connect

    Hammer, D.A.

    1989-01-01

    A conference on constructed wetlands for waste water treatment is presented. Thirty-seven of the articles presented at the conference have been abstracted and indexed for the U.S. Department of Energy's Energy Data Base.

  10. Constructed wetland technology transfer to Nepal.

    PubMed

    Shrestha, R R; Haberl, R; Laber, J

    2001-01-01

    Constructed Wetland (CW) technology is still not wide spread in developing countries despite having great potential. This paper describes an approach carried out in Nepal to transfer CW technology for wastewater treatment. Three CWs (hospital wastewater treatment--20 m3/d, greywater treatment of a single household, septage treatment--40 m3/d) were built and two have been investigated so far. All systems are subsurface flow systems with at least one vertical flow stage. Their treatment efficiency turned out to be very high. Median load elimination rates of the hospital wastewater and greywater treatment plants were for TSS: 97 to 99%; BOD5: 97 to 99%; COD: 94 to 97%; NH4-N 80 to 99%; PO4-P: 5 to 69%; Total Coliforms: 99.87 to 99.999% (3-5 log steps). Beside the treatment task the plants play an important role as demonstration sites to make common people and especially decision makers aware of the existing environmental problems and one possible solution. Several recommendations are pointed out to promote the technology in developing countries.

  11. 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.

  12. '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.

  13. Handbook for constructed wetlands receiving acid mine drainage

    SciTech Connect

    Wildeman, T.; Dietz, J.; Gusek, J.; Morea, S.

    1993-09-01

    In the summer of 1987, a pilot constructed wetland was built at the Big Five Tunnel in Idaho Springs, Colorado. The 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, which was funded by the U.S. Environmental Protection Agency under the SITE Emerging Technologies Program. The text is divided into two broad sections: Part A - Theoretical Development, and Part B - Design Consideration. In the latter sections of Part A and through all of Part B the focus is on removal of metals by precipitation of sulfides through the activity of sulfate reducing bacteria.

  14. [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. PMID:20391699

  15. [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.

  16. Ultraviolet disinfection of effluent from subsurface flow constructed wetlands.

    PubMed

    Richter, A Y; Weaver, R W

    2003-09-01

    Subsurface flow constructed wetlands are becoming increasingly common for on-site treatment of domestic wastewater. Before spray application, wetland effluent must be disinfected. Traditionally, tablet chlorination has been used, but an alternative is needed to increase dependability. Consequently, we investigated the use of ultraviolet light disinfection of effluent from constructed wetlands. Two low pressure (254 nm) and two medium pressure ultraviolet bulbs (190 to 400 nm) were used for disinfection. Upon installation, all units disinfected effluent successfully. After 2 weeks in operation, three of the four units did not reduce fecal coliform populations below 200 in 100 ml of effluent due to decreased light intensity from films that developed on the bulbs. One unit consistently disinfected water to populations lower than 200 in 100 ml for 1 year without maintenance. Ultraviolet disinfection, as utilized, was not consistently suitable for disinfection of effluent from subsurface flow constructed wetlands because of coatings that developed on the bulbs and blocked the light.

  17. Modeling the effects of constructed wetland on nonpoint source pollution control and reservoir water quality improvement.

    PubMed

    Ham, Jonghwa; Yoon, Chun G; Kim, Hyung-Joong; Kim, Hyung-Chul

    2010-01-01

    This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The experimental field-scale wetland systems (four sets, 0.88 ha each) have been in operation since 2002, where water depth was maintained at 30-50 cm and hydraulic loading rate was at 6.3-18.8 cm/day. The wetland system was found to be adequate for treating polluted stream water with stable removal efficiency even during the winter. The integrated modeling system (modified-BASINS) was applied to the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The calibrated integrated modeling system estimated that constructing wetlands on 0.5% (about 114 ha) of the watershed area at the mouth of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%-1.0% of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir at the polder area where land use planning is relatively less complicated.

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

    SciTech Connect

    Steiner, G.R.; Watson, J.T.; Choate, K.D.

    1991-03-01

    A constructed wetlands system (CW) treats wastewater through natural water quality improvement processes (physical, chemical and biological) that occur in natural wetlands. Proper design, construction and operation of a CW optimize the processes. Treatment by CW can be effective, reliable, simple and relatively inexpensive as compared to conventional systems. CW systems can be built for wide flow ranges, including sources having relatively small flows (e.g., individual homes, small businesses and schools). A CW is an alternative for a small system where conventional on-site methods are ineffective due to poor site conditions (e.g., low soil percolation, shallow soils, high groundwater table, Karst topography). 4 figs.

  19. 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.

  20. Long-term performance of vertical-flow and horizontal-flow constructed wetlands as affected by season, N load, and operating stage for treating nitrogen from domestic sewage.

    PubMed

    Kim, Seong-Heon; Cho, Ju-Sik; Park, Jong-Hwan; Heo, Jong-Soo; Ok, Yong-Sik; Delaune, Ronald D; Seo, Dong-Cheol

    2016-01-01

    To investigate the long-term nitrogen treatment efficiency in vertical-flow (VF)-horizontal-flow (HF) hybrid constructed wetlands (CWs), the nitrogen removal efficiency under different seasons, N loads, and three operating stages (representing age of the wetland) were evaluated over a 12-year period. The average total nitrogen (TN) removal efficiencies in the effluent during the operation period were in the following order: summer (75.2%) > spring (73.4%) ≒ autumn (72.6%) > winter (66.4%). The removal efficiencies of TN in summer, autumn, and spring were generally higher than those in winter. At different stages of operation (years), the average TN removal rates in the effluent were in the following order: middle stage (73.4%; years 2006-2009) > last stage (72.0%; years 2010-2013) > beginning stage (70.1%; years 2002-2005). In VF-HF CWs, the amount of average TN removal (mg N m(-2) day(-1)) over the 12-year period was in the order of summer (5.5) ≒ autumn (5.1) > spring (4.3) ≒ winter (4.2) for the VF bed and in the order of summer (3.5) ≒ spring (3.5) ≒ autumn (3.3) > winter (2.7) for the HF bed, showing that the amount of TN removal per unit area (m(2)) in summer was slightly greater than that in other seasons. The amount of TN removal in the VF bed was slightly greater than that in the HF bed. Using three-dimensional simulation graphs, the maximum TN removal rate was at inflow N loads below 2.7 g m(-2) day(-1) in the summer season, whereas the minimum TN removal rate was at inflow N loads below 1.4 g m(-2) day(-1) in the winter season. Consequently, the TN removal efficiency was very stable over the 12 years of operation in VF-HF hybrid CWs. Results demonstrate that the VF-HF hybrid CWs possess good buffer capacity for treating TN from domestic sewage for extended periods of time.

  1. Long-term performance of vertical-flow and horizontal-flow constructed wetlands as affected by season, N load, and operating stage for treating nitrogen from domestic sewage.

    PubMed

    Kim, Seong-Heon; Cho, Ju-Sik; Park, Jong-Hwan; Heo, Jong-Soo; Ok, Yong-Sik; Delaune, Ronald D; Seo, Dong-Cheol

    2016-01-01

    To investigate the long-term nitrogen treatment efficiency in vertical-flow (VF)-horizontal-flow (HF) hybrid constructed wetlands (CWs), the nitrogen removal efficiency under different seasons, N loads, and three operating stages (representing age of the wetland) were evaluated over a 12-year period. The average total nitrogen (TN) removal efficiencies in the effluent during the operation period were in the following order: summer (75.2%) > spring (73.4%) ≒ autumn (72.6%) > winter (66.4%). The removal efficiencies of TN in summer, autumn, and spring were generally higher than those in winter. At different stages of operation (years), the average TN removal rates in the effluent were in the following order: middle stage (73.4%; years 2006-2009) > last stage (72.0%; years 2010-2013) > beginning stage (70.1%; years 2002-2005). In VF-HF CWs, the amount of average TN removal (mg N m(-2) day(-1)) over the 12-year period was in the order of summer (5.5) ≒ autumn (5.1) > spring (4.3) ≒ winter (4.2) for the VF bed and in the order of summer (3.5) ≒ spring (3.5) ≒ autumn (3.3) > winter (2.7) for the HF bed, showing that the amount of TN removal per unit area (m(2)) in summer was slightly greater than that in other seasons. The amount of TN removal in the VF bed was slightly greater than that in the HF bed. Using three-dimensional simulation graphs, the maximum TN removal rate was at inflow N loads below 2.7 g m(-2) day(-1) in the summer season, whereas the minimum TN removal rate was at inflow N loads below 1.4 g m(-2) day(-1) in the winter season. Consequently, the TN removal efficiency was very stable over the 12 years of operation in VF-HF hybrid CWs. Results demonstrate that the VF-HF hybrid CWs possess good buffer capacity for treating TN from domestic sewage for extended periods of time. PMID:26298340

  2. 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.

  3. 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).

  4. The Springdale project: Applying constructed wetland treatment to coal combustion by-product leachate. Final report

    SciTech Connect

    Rightnour, T.A.; Hoover, K.L.

    1998-11-01

    The Springdale constructed wetland treatment system was completed in 1995 under an Electric Power Research Institute tailored collaboration agreement with Allegheny Power to test the operational and economic feasibility of using constructed wetland technologies to treat coal combustion by-product leachate. The system design incorporates an oxidation/precipitation basin, vegetated wetlands, manganese-oxidizing rock drains, an organic upflow cell, an algal uptake basin, and a greenhoused phytoremediation research facility. Influent and effluent chemical loadings to the individual system components have been monitored for a period of two years. Results show the system to be highly effectively in treating aqueous metals, with concentration reductions for the primary parameters being 98% for iron, 92% for manganese, and 71% for aluminum, along with significant reductions in other trace metals and concurrent improvements in pH and alkalinity. NPDES compliance has been achieved for all aqueous metals parameters except boron, which does not appear to be treatable by any means on this site. A cost comparison to four conventional chemical treatment alternatives indicates that capital investment would be comparable between constructed wetlands and chemical treatment, while significant long-term savings are predicted for the constructed wetland system due to lower operational and maintenance costs. The estimated 50 year present value savings for the constructed wetland system is approximately $1.271 million over the least expensive chemical treatment alternative, and $3.731 million over the most expensive. Operational and maintenance cost savings are primarily the result of lower on-site labor and lower waste disposal costs due to denser sludge formation in the wetland system.

  5. Flow patterns of dairy wastewater constructed wetlands in a cold climate.

    PubMed

    Muñoz, Pete; Drizo, Aleksandra; Cully Hession, W

    2006-10-01

    Conservative tracer experiments, and spatial temperature and dissolved oxygen mapping within four subsurface treatment wetlands employed in this study demonstrated the importance of supplemental aeration and vegetation in reducing preferential flows in cold climate treatment wetlands. Four constructed wetlands, employing horizontal subsurface flow were used to treat dairy wastewater in a 2 x 2 factorial design consisting of two wetland cells with vegetation and two with supplemental aeration. Four tracer studies were conducted between November 2004 and May 2005. Two key observations were made, demonstrating that vegetation and aeration can be utilized in cold regions to prevent clogging and freezing, thereby reducing preferential flow paths which can reduce treatment efficiencies: (1) vegetation contributed to thermal protection and (2) aeration increased temperature and mixing. A comparison of multiple wetland cells with varying flow rates showed that the use of pore volume in tracer response curves was a better indicator of preferential flows than other indicators including volumetric efficiency, hydraulic efficiency and number of continuosly stirred tank reactors (CSTRs). This research helps further establish how constructed wetlands are a viable tool for treating wastewater in cold climates.

  6. 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.

  7. 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...

  8. Danish guidelines for small-scale constructed wetland systems for onsite treatment of domestic sewage.

    PubMed

    Brix, H; Arias, C A

    2005-01-01

    The Danish Ministry of Environment and Energy has passed new legislation that requires the wastewater from single houses and dwellings in rural areas to be treated adequately before discharge into the aquatic environment. Therefore official guidelines for a number of onsite treatment solutions have been produced. These include guidelines for soakaways, biological sand filters, technical systems as well as different types of constructed wetland systems. This paper summarises briefly the guidelines for horizontal flow constructed wetlands, vertical flow constructed wetlands, and willow systems with no outflow and with soil infiltration. There is still a lack of a compact onsite solution that will fulfil the treatment classes demanding 90% removal of phosphorus. Therefore work is presently being carried out to identify simpler and robust P-removal solutions. PMID:16042237

  9. Economic valuation of a created wetland fed with treated wastewater located in a peri-urban park in Catalonia, Spain.

    PubMed

    Alfranca, Oscar; García, Joan; Varela, Hector

    2011-01-01

    The main objective of this study was to calculate the economic value (including externalities) of a created wetland located in a peri-urban park in Catalonia, Spain. The wetland, which covers an area of 1 ha, was constructed in 2003 and receives a secondary treated wastewater flow of between 100 and 250 m(3)/day. The externalities of the wetland were evaluated using the travel cost method. The value of the wetland is expressed in terms of the price of the water that flows through the system, which is estimated to range from 0.71 to 0.75 €/m(3). The value of positive externalities (1.25 €/m(3)) was greater than private costs (from 0.50 to 0.54 €/m(3)). These results constitute empirical evidence that created wetlands in peri-urban parks can be considered to be a source of positive externalities when used in environmental restoration projects focusing on the reuse of treated wastewater. This study also illustrates 1) the small influence of the hydraulic infrastructure depreciation costs on the private costs of constructed wetlands (less than 10%), and 2) the low investment costs of constructed wetlands in comparison with operation and maintenance costs (less than 10% of total private costs). PMID:21411938

  10. Economic valuation of a created wetland fed with treated wastewater located in a peri-urban park in Catalonia, Spain.

    PubMed

    Alfranca, Oscar; García, Joan; Varela, Hector

    2011-01-01

    The main objective of this study was to calculate the economic value (including externalities) of a created wetland located in a peri-urban park in Catalonia, Spain. The wetland, which covers an area of 1 ha, was constructed in 2003 and receives a secondary treated wastewater flow of between 100 and 250 m(3)/day. The externalities of the wetland were evaluated using the travel cost method. The value of the wetland is expressed in terms of the price of the water that flows through the system, which is estimated to range from 0.71 to 0.75 €/m(3). The value of positive externalities (1.25 €/m(3)) was greater than private costs (from 0.50 to 0.54 €/m(3)). These results constitute empirical evidence that created wetlands in peri-urban parks can be considered to be a source of positive externalities when used in environmental restoration projects focusing on the reuse of treated wastewater. This study also illustrates 1) the small influence of the hydraulic infrastructure depreciation costs on the private costs of constructed wetlands (less than 10%), and 2) the low investment costs of constructed wetlands in comparison with operation and maintenance costs (less than 10% of total private costs).

  11. 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. PMID:25026582

  12. 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

  13. 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.

  14. 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. PMID:17353090

  15. 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.

  16. 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.

  17. 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. PMID:24912241

  18. Feasibility of using constructed wetland treatment for molasses wastewater treatment.

    PubMed

    Sohsalam, Prapa; Sirianuntapiboon, Suntud

    2008-09-01

    The surface flow constructed wetland (SFCW) with Cyperus involucratus, Typha augustifolia and Thalia dealbata J. Fraser was applied to treat anaerobic treated-molasses wastewater (An-MWW) under the organic loading rates (OLRs) of 612, 696, 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1). The results showed that both removal efficiency and plant growth rate were increased with the decrease of organic loading rate (OLR). All tested-plant species could not grow under OLR of higher than 696 kg BOD(5)mg l(-1) (p>0.05). Also, the plant-biomass of the systems was reduced by 10.4%, 26.5%, and 64.7% of initial plant-biomass under the OLR of 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1), respectively. However, all tested-plant species showed the same pattern on the plant-biomass production yield and removal efficiency. The highest SS, BOD, COD, total phosphorus, NH(4)(+), NO(3)(-) and molasses pigments (MP) removal efficiencies of 90-93%, 88-89%, 67%, 70-76%, 77-82%, 94-95% and 72-77%, respectively were detected under the OLR of 612 kg BOD(5)ha(-1)day.

  19. 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. PMID:25401309

  20. Performance of an innovative FWS constructed wetland in Crete, Greece.

    PubMed

    Dialynas, G; Kefalakis, N; Dialynas, M; Angelakis, A

    2002-01-01

    Pompia is an ancient name of a small community in Messara valley, which is the main agricultural area, in central Crete. The constructed wetland in Pompia is a free water surface (FWS) system, for treating the wastewater of the local community of 1,200 p.e. That wastewater treatment plant (WWTP) is a pilot plant but it is simple, safe, innovative, and environmentally friendly. The WWTP was funded by the Region of Crete. The Eastern Crete Development Organization was responsible for the design, supervision, management, and initial operation. The project was completed in August 1999, and has been under operation since then. The effluent is considered to be equivalent to tertiary treated municipal wastewater, and it will be used to irrigate olive orchards. The general sense for a visitor is that the FWS system operates like a natural marsh and a habitat of birds and wild animals. In addition, very high removal rates for BOD5, COD, TSS, TKN, TP, TC, and FC have been obtained.

  1. 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.

  2. 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. PMID:26976008

  3. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 '...

  4. Constructed wetlands to control nonpoint-source pollution

    SciTech Connect

    Wengrzynek, R.L.

    1991-01-01

    The use of land for agriculture, urban development, and recreational purposes results in pollution that has potential to contaminate groundwater, streams, lakes and oceans. Aquatic ecosystems can be damaged by even small amounts of pollutants in runoff during storms and by cumulative impacts of chronic, low levels of pollution. Nutrients, pesticides and sediments can have long term effects on the ecosystems. The instant invention using constructed wetlands has been particularly useful for purposes of protecting ecosystems from untoward effects of nonpoint source pollution. The construct, containing in hydraulic order a sediment basin, level-lip spreader, grassy filter, wetland, and deep pond can be used to remove pollutants from nonpoint source runoff. Wetlands are planted with vegetation that encourages growth of aerobic and anaerobic bacteria, which are helpful in removing and detoxifying contaminants.

  5. Ammonia removal in constructed wetlands receiving oil sands wastewater

    SciTech Connect

    Bishay, F.S.; Bayley, S.E.; Nix, P.G.

    1995-12-31

    Constructed wetlands are a component of the mine decommissioning and reclamation plan for Suncor Inc., Oil Sands Group, a large oil sands mining and extraction operation in northeastern Alberta, A field, pilot-scale wetlands facility was built in 1991. Over a three year period (1992--1994) the feasibility of constructed wetlands as treatment systems for various oil sands wastewater streams was assessed. Ammonia and hydrocarbons are the primary contaminants. Ammonia removal rates were estimated by measuring inputs and outputs of ammonia, changes in storage, and removal processes. These removal rates were comparable to rates in other studies indicating that the presence of hydrocarbons was not limiting ammonia removal. Nitrogen in sediments and vegetation was elevated; however, removal to sediments or vegetation did not contribute significantly to overall ammonia removal. Volatilization and denitrification were measured in situ. Although neither of these measured processes accounted for all of the ammonia removal, nitrification/denitrification was thought to be the primary removal mechanism.

  6. 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%).

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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. PMID:14587952

  12. 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...

  13. 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 ...

  14. 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...

  15. 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.

  16. Hydrocarbon removal in an experimental gravel bed constructed wetland.

    PubMed

    Omari, K; Revitt, M; Shutes, B; Garelick, H

    2003-01-01

    Two outdoor subsurface flow beds (control and experimental, 10 m x 1 m) were filled with a substrate of pea gravel (3-6 mm) to a depth of 60 cm. The experimental bed or small-scale constructed wetland was originally planted with Typha seedlings at a density of 7.5 plants/m2. Both beds (experimental and control) were treated with the same aqueous concentrations of diesel oil under identical dosing conditions. The average overall hydrocarbon removal efficiencies at the three monitored depths (top, middle and bottom) in the subsurface systems were 80.1 +/- 9.8%, 78.0 +/- 9.1% and 71.6 +/- 10.0% in the experimental bed and 72.3 +/- 11.9%, 69.1 +/- 10.3% and 63.4 +/- 9.4% in the control bed. The differences in the hydrocarbon removal efficiencies between corresponding months in 1999 and 2000 were statistically analysed and are generally not significant. The individual hydrocarbon removal efficiencies exceeded 60% in the top sections of both beds except for C-11 and C-25 with C-23 and C-26 also reduced in the control bed. Overall differences in the removal efficiencies of the planted and the unplanted beds as well as at different depths in both systems, indicate that Typha related removal processes complementing adsorption onto the gravel substrate are occurring.

  17. 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.

  18. Innovative approach for restoring coastal wetlands using treated drill cuttings

    SciTech Connect

    Veil, J. A.; Hocking, E. K.

    1999-11-02

    The leading environmental problem facing coastal Louisiana regions is the loss of wetlands. Oil and gas exploration and production activities have contributed to wetland damage through erosion at numerous sites where canals have been cut through the marsh to access drilling sites. An independent oil and gas producer, working with Southeastern Louisiana University and two oil field service companies, developed a process to stabilize drill cuttings so that they could be used as a substrate to grow wetlands vegetation. The U.S. Department of Energy (DOE) funded a project under which the process would be validated through laboratory studies and field demonstrations. The laboratory studies demonstrated that treated drill cuttings support the growth of wetlands vegetation. However, neither the Army Corps of Engineers (COE) nor the U.S. Environmental Protection Agency (EPA) would grant regulatory approval for afield trial of the process. Argonne National Laboratory was asked to join the project team to try to find alternative mechanisms for gaining regulatory approval. Argonne worked with EPA's Office of Reinvention and learned that EPA's Project XL would be the only regulatory program under which the proposed field trial could be done. One of the main criteria for an acceptable Project XL proposal is to have a formal project sponsor assume the responsibility and liability for the project. Because the proposed project involved access to private land areas, the team felt that an oil and gas company with coastal Louisiana land holdings would need to serve as sponsor. Despite extensive communication with oil and gas companies and industry associations, the project team was unable to find any organization willing to serve as sponsor. In September 1999, the Project XL proposal was withdrawn and the project was canceled.

  19. Iron and manganese diagenesis in constructed wetlands receiving mine drainage

    SciTech Connect

    Tarutis, W.J. Jr.

    1993-01-01

    The chemical diagenesis of iron and manganese was studied in two constructed wetlands receiving coal mine drainage and in laboratory wetland mesocosms exposed to synthetic acidic mine waters, and the release of soluble metals from natural and synthetic metal oxides of differing crystallinity was studied in laboratory incubations in the presence and absence of bacterial sulfate reduction. Soil chemical characterization indicated that the formation of potentially reducible, oxide-bound precipitates accounted for the majority of iron and manganese removed in the two wetlands studied. Depth profiles revealed diagenetic remobilization of iron and manganese to the soil interstitial water due to the reductive dissolution of oxidized metals initially deposited on the wetland surface. Sulfate reduction and pyrite formation contributed little to metal removal due to organic carbon limitation in the subsurface soils. Iron and manganese in synthetic acidic mine water added to anoxic wetland mesocosms acted synergistically with respect to metal removal. The inclusion of sulfate in synthetic mine water caused a slightly greater, but statistically significant, iron removal in mesocosms relative to mesocosms not receiving sulfate. Sulfate addition had no effect on manganese removal. Iron was much more reactive than manganese towards sulfide in laboratory incubations in which sulfate reduction was allowed to occur. Liberation of iron and manganese in the absence of sulfate reduction decreased with increasing crystallinity of each metal oxide tested and was attributed to higher activation energies characteristic of a surface-reaction-controlled dissolution mechanisms.

  20. On-site wastewater treatment using subsurface flow constructed wetlands in Ireland.

    PubMed

    Gill, Laurence W; O'Luanaigh, Niall; Johnston, Paul M

    2011-01-01

    The results from an Irish EPA-funded project on the effectiveness of using constructed wetlands for treating wastewater from single households is presented, which has contributed to the design guidelines included in the new EPA Code of Practice. Three subsurface flow gravel-filled wetlands were constructed on separate sites--one to provide secondary treatment and the other two to provide tertiary treatment stages for the domestic effluent. A comprehensive analysis over three years was then conducted to provide a robust characterization of the internal dynamics of the systems, particularly with respect to N and P removal as well as evaluating the temporal water balance across the different seasons. The removal of Total N was only 29% and 30% in the secondary and tertiary treatment wetlands, respectively; particularly disappointing for the tertiary treatment process, which was receiving nitrified effluent. Studies on the (15)N stable isotope confirmed that 35% of the ammonium from the septic tank was passing straight through the process without taking part in any biogeochemical processes. However, influent N in the wetlands was shown to be biologically assimilated into organic nitrogen and then released again as soluble ammonium--so-called nitrogen "spiraling." Removal of Total P in the wetlands averaged from 28% to 45% with higher P removals measured during summer periods, although the effluent concentrations were still found to be high (> 5 mg/l on average). The phosphorus in the plant material was also analysed revealing that the annual above-ground stem matter only accounted for 1.3% to 8.4% of the annual total P-load in the wetlands. Finally, the water balance analyses showed that the mean flow discharging from both the secondary and tertiary treatment wetlands was slightly greater than the mean flow to the reed bed over the trial period, with rainfall acting to increase flows by 13% and 5%, respectively, on average in winter while just about balancing

  1. 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.

  2. The effect of heavy metals on nitrogen and oxygen demand removal in constructed wetlands.

    PubMed

    Lim, P E; Tay, M G; Mak, K Y; Mohamed, N

    2003-01-01

    The objective of this study is to investigate the respective effects of Zn, Pb and Cd as well as the combined effect of Zn, Pb, Cd and Cu on the removal of nitrogen and oxygen demand in constructed wetlands. Four laboratory-scale gravel-filled subsurface-flow constructed wetland units planted with cattails (Typha latifolia) were operated outdoors and fed with primary-treated domestic wastewater at a constant flow rate of 25 ml/min. After 6 months, three of the wetland units were fed with the same type of wastewater spiked with Zn(II), Pb(II) and Cd(II), respectively, at 20, 5 and 1 mg/l for a further 9 months. The remaining unit was fed with the same type of wastewater spiked with a combination of Zn(II), Pb(II), Cd(II) and Cu(II) at concentrations of 10, 2.5, 0.5 and 5 mg/l, respectively, over the same period. The chemical oxygen demand (COD) and ammoniacal nitrogen (AN) concentrations were monitored at the inlet, outlet and three additional locations along the length of the wetland units to assess the performance of the wetland units at various metal loadings. At the end of the study, all cattail plants were harvested for the determination of total Kjeldahl nitrogen and metal concentrations. The results showed that the COD removal efficiency was practically independent of increasing metal loading or a combination of metal loadings during the duration of the study. In contrast, the AN removal efficiency deteriorated progressively with increasing metal loading. The relative effect of the heavy metals was found to increase in the order: Znwetland systems treating domestic wastewater only.

  3. Changes in the planktonic microbial community during residence in a surface flow constructed wetland used for tertiary wastewater treatment.

    PubMed

    Mulling, Bram T M; Soeter, A Marieke; van der Geest, Harm G; Admiraal, Wim

    2014-01-01

    Suspended particles are a major constituent of municipal wastewater and generally contain high levels of bacteria, including human pathogens. Discharge of these particles of anthropogenic nature can have profound effects on receiving aquatic ecosystems and mitigation of these effects requires additional polishing of treated municipal wastewater. Previously it was shown that surface flow constructed wetlands are effective in improving water quality by reducing the numbers of fecal indicator organisms. However, fecal indicator organisms represent only a minor fraction of the total planktonic bacterial community and knowledge on the effects of these constructed wetlands on the composition and functioning of the entire planktonic bacterial community is limited. The aim of this descriptive study was therefore to identify changes in the planktonic bacterial community during residence of secondary treated municipal wastewater in a full-scale surface flow constructed wetland. To this purpose water samples were taken in which the bacterial community composition and functioning were analyzed using FISH, DGGE and BIOLOG. Surprisingly, the bacterial abundance at the inflow of the constructed wetland was relatively low compared with more natural surface waters. However, the inflowing bacterial community showed high metabolic activity and functional diversity. During residence in the surface flow constructed wetland the bacterial abundance doubled, but decreased in metabolic activity and functional diversity. Shifts in the community composition indicate that these changes are related to turn-over of the bacterial community. The planktonic bacterial community in the effluent of the constructed wetland closely resembled natural bacterial communities in urban and agricultural ditches. Based on these observations we conclude that constructed wetlands are capable to mitigate possible impacts of the particle load in treated wastewaters by transforming the anthropological bacterial

  4. 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.

  5. 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. PMID:24534015

  6. 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.

  7. 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.

  8. 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. PMID:26521546

  9. 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

  10. 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

  11. 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.

  12. 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. PMID:14977152

  13. [Effect of constructed wetland on the purification of industrial zone rainfall runoff contaminated with phenanthrene].

    PubMed

    Jing, Dan-Dan; Wan, Jin-Quan; Ma, Yong-Wen; Li, Dong-Ya; Wang, Yan; Huang, Ming-Zhi

    2013-08-01

    According to the water characteristics of industrial rainfall runoff in the catchment of Tongsha Reservoir, Dongguan City, a subsurface-flow constructed wetland (SSFCW) was used to treat simulated rainfall and the spatial variation of removal efficiency of contaminants in the wetland bed was analyzed. The longitudinal and vertical variation of removal efficiency of COD, NH4(+) -N, TN, TP and phenanthrene were examined. Enzyme activity of polyphenol oxidase (PPO) and nitrate reductase (NR) along the wetland bed were analyzed as well, meanwhile, four biogeochemical indexes of the wetland system, including DO, pH, ORP and water temperature, were monitored and their influences on the removal efficiency of contaminants and enzyme activity were analyzed. Results showed that DO, pH, ORP, water temperature all presented a decreasing tendency along the wetland bed, and the removal of COD, TP and phenanthrene occurred mainly in the front quarter of the wetland system; in the vertical direction, DO and ORP in the upper wetland bed were significantly higher than those in the ground floor, suggesting that the horizontal subsurface system was in an anaerobic or anoxic condition. The removal rates of COD, TP, TN, NH4(+) -N and phenanthrene were 1.17-1.36, 2.04-2.11, 1.40-1.92, 1.37-2.30, and 1.07-1.36 times higher than those at the bottom, respectively. Therefore, the vertical variation of purification efficiency was more significant than the longitudinal variation. A significant positive correlation was determined between the enzyme activity of NR and the NO3(-) -N concentration, but the longitudinal variation in the enzyme activity of NR and PPO was not obvious.

  14. Efficiency of constructed wetlands for residential wastewater treatment

    SciTech Connect

    Leonard, K.M.

    1998-07-01

    One of the major water quality concerns in many areas of the country is finding alternative methods for on-site, residential wastewater treatment systems. In response to this issue, there has recently been a rush of interest in constructed wetlands as a practical, natural alternative. This paper documents the performance of such residential systems under for a broad range of temperatures and recommends adjusted input parameters for the two most popular design models.

  15. Nitrogen Isotopes - Tracers for Nitrogen Transformations in Small Constructed Wetlands

    NASA Astrophysics Data System (ADS)

    Reinhardt, M.; Gaechter, R.; Mueller, B.; Wehrli, B.

    2005-05-01

    Small artificial wetlands are increasingly applied to reduce non-point source pollution and to contribute to the restoration of eutrophicated freshwaters and coastal marine ecosystems. In the agricultural catchment area of Lake Sempach in Central Switzerland, several wetlands were constructed at the interface between subsurface drainage system and receiving waters. In order to evaluate nitrogen retention efficiency of the systems and to identify major processes controlling their performance, nitrate, ammonium, particulate and dissolved organic nitrogen in the inflowing and outflowing water as well as δ15N of nitrate, ammonium and sediment were analyzed in a three pond system. During the studied 26 months the wetland retained 27% of the nitrogen load corresponding to a surface related retention of 51g N m-2 yr-1. Nitrate in the inlet contributed 48% to the total nitrogen load and was characterized by high δ15N-NO3(>13‰) typical for intensively manured grassland soils. Increasing δ15N-NO3 in the wetland compared to the inlet was attributed to denitrification whereas decreasing δ15N-NO3 during stagnant periods was due to anoxic mineralization of particulate organic matter and subsequent nitrification.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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).

  1. The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: a review of a recent development.

    PubMed

    Vymazal, Jan

    2013-09-15

    The hybrid systems were developed in the 1960s but their use increased only during the late 1990 s and in the 2000s mostly because of more stringent discharge limits for nitrogen and also more complex wastewaters treated in constructed wetlands (CWs). The early hybrid CWs consisted of several stages of vertical flow (VF) followed by several stages of horizontal flow (HF) beds. During the 1990 s, HF-VF and VF-HF hybrid systems were introduced. However, to achieve higher removal of total nitrogen or to treat more complex industrial and agricultural wastewaters other types of hybrid constructed wetlands including free water surface (FWS) CWs and multistage CWs have recently been used as well. The survey of 60 hybrid constructed wetlands from 24 countries reported after 2003 revealed that hybrid constructed wetlands are primarily used on Europe and in Asia while in other continents their use is limited. The most commonly used hybrid system is a VF-HF constructed wetland which has been used for treatment of both sewage and industrial wastewaters. On the other hand, the use of a HF-VF system has been reported only for treatment of municipal sewage. Out of 60 surveyed hybrid systems, 38 have been designed to treat municipal sewage while 22 hybrid systems were designed to treat various industrial and agricultural wastewaters. The more detailed analysis revealed that VF-HF hybrid constructed wetlands are slightly more efficient in ammonia removal than hybrid systems with FWS CWs, HF-VF systems or multistage VF and HF hybrid CWs. All types of hybrid CWs are comparable with single VF CWs in terms of NH4-N removal rates. On the other hand, CWs with FWS units remove substantially more total nitrogen as compared to other types of hybrid constructed wetlands. However, all types of hybrid constructed wetlands are more efficient in total nitrogen removal than single HF or VF constructed wetlands.

  2. 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.

  3. 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.

  4. 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.

  5. Pilot-scale constructed wetlands for petroleum-contaminated groundwater.

    PubMed

    Bedessem, Marjorie E; Ferro, Ari M; Hiegel, Trevor

    2007-06-01

    A pilot study was conducted to determine the feasibility of using constructed treatment wetlands to remediate recovered groundwater from the subsurface of a former refinery site. The pilot system consisted of four subsurface flow treatment cells operated in an upward vertical flow mode and equipped with subsurface aeration lines. The treatment system showed minimal capability for methyl-tert-butyl ether removal, but did effectively remove total petroleum hydrocarbons-deisel range organics and total benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes (total BTEX). Effluent benzene concentrations were less than 0.05 mg/L in 70% of the samples from a treatment cell using subsurface aeration and a wetland sod amendment. Based on 1 year of operating data, cumulative mass removal approached 80% for benzene and 88% for total BTEX.

  6. Effects of influent C/N ratios on wastewater nutrient removal and simultaneous greenhouse gas emission from the combinations of vertical subsurface flow constructed wetlands and earthworm eco-filters for treating synthetic wastewater.

    PubMed

    Zhao, Yongjun; Zhang, Yuejin; Ge, Zhigang; Hu, Changwei; Zhang, Hui

    2014-03-01

    This research focused on the nutrient removal and the simultaneous CO2, CH4, and N2O emission rates of various combinations of vertical subsurface flow constructed wetlands (VSFCWs) and earthworm eco-filters (EEs) under different influent C/N ratios in synthetic wastewater. The optimal parameters for nutrient removal were influent C/N ratios of 5 : 1 and 10 : 1 as well as the combination VSFCW-EE. Relatively low values of greenhouse gas (GHG) emission rates measured in situ were obtained at a C/N ratio of 5 : 1. The emission rates of CH4 and N2O were considerably lower than that of CO2. The VSFCW-EE and EE-VSFCW combinations showed similar GHG emission results. The C/N ratio of 5 : 1 and the VSFCW-EE combination exhibited the highest nutrient removal efficiency with the lowest GHG emission rate. Wastewater nutrient removal and GHG emission were both high during summer (June to August) and low during winter (December to February).

  7. Evaluation of Subsurface Flow and Free-water Surface Wetlands Treating NPR-3 Produced Water - Year No. 1

    SciTech Connect

    Myers, J. E.; Jackson, L. M.

    2001-10-13

    This paper is a summary of some of the activities conducted during the first year of a three-year cooperative research and development agreement (CRADA) between the Department of Energy (DOE) Rocky Mountain Oilfield Testing Center (RMOTC) and Texaco relating to the treatment of produced water by constructed wetlands. The first year of the CRADA is for design, construction and acclimation of the wetland pilot units. The second and third years of the CRADA are for tracking performance of pilot wetlands as the plant and microbial communities mature. A treatment wetland is a proven technology for the secondary and tertiary treatment of produced water, storm water and other wastewaters. Treatment wetlands are typically classified as either free-water surface (FWS) or subsurface flow (SSF). Both FWS and SSF wetlands work well when properly designed and operated. This paper presents a collection of kinetic data gathered from pilot units fed a slipstream of Wyoming (NPR-3) produced water. The pilot units are set up outdoors to test climatic influences on treatment. Monitoring parameters include evapotranspiration, plant growth, temperature, and NPDES discharge limits. The pilot wetlands (FWS and SSF) consist of a series of 100-gal plastic tubs filled with local soils, gravel, sharp sand and native wetland plants (cattail (Typha spp.), bulrush (Scirpus spp.), dwarf spikerush (Eleocharis)). Feed pumps control hydraulic retention time (HRT) and simple water control structures control the depth of water. The treated water is returned to the existing produced water treatment system. All NPDES discharge limits are met. Observations are included on training RMOTC summer students to do environmental work.

  8. Pilot treatment of olive pomace leachate by vertical-flow constructed wetland and electrochemical oxidation: an efficient hybrid process.

    PubMed

    Grafias, Petros; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios; Diamadopoulos, Evan

    2010-05-01

    A hybrid process comprising biological degradation in a vertical-flow constructed wetland (CW) and electrochemical oxidation over boron-doped diamond electrodes to decolorize, mineralize and detoxify a leachate from olive pomace processing (OPL) was investigated. Two alternative treatment schemes were compared: According to the first treatment scheme, OPL was treated by electrochemical oxidation followed by treatment in a constructed wetland pilot unit (CW-A). The second scheme comprised of treatment in a constructed wetland followed by electrochemical treatment (CW-B). The constructed wetlands units were planted with Phragmites australis (reeds) and were fed intermittently at organic loadings between 5 and 15 g COD m(-2) d(-1) and a residence time of 3 d. Electrochemical oxidation (EO) was performed for 360 min at 20 A. Treatment of OPL in the wetland at 15 g COD m(-2) d(-1) led to mean COD and color reduction of 86% and 77%, respectively; the wetland effluent with a COD of about 800 mg L(-1) was polished electrochemically for 360 min after which the overall COD and color removal of the combined process (i.e. CW-B/EO) was around 95%, while the final effluent was not toxic against the marine bacteria Vibrio fischeri. Electrochemical oxidation of the original OPL at COD values between 6250 and 14 100 mg L(-1) led to moderate COD and color reduction (i.e. less than 40%) through zero order kinetics. When this was coupled to constructed wetland post-treatment (i.e. EO/CW-A), the overall COD and color removal was 81% and 58%, respectively. The decreased efficiency may be assigned to the increased toxicity of the electrochemically treated effluent which was only partially removed in the natural treatment system. PMID:20199791

  9. 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.

  10. [Excitation-Emission Matrix Fluorescence Spectra Characteristics of DOM in a Combined Constructed Wetland].

    PubMed

    Lü, Jing-jing; Zhang, Lie-yu; Xi, Bei-dou; Hou, Li-an; Li, Ming

    2015-08-01

    Using three-dimensional fluorescence technology, we studied fluorescent characteristics of two polluted rivers by a surface flow+vertical flow combined constructed wetlands of dissolving organic matter. The results showed that (1) the main sources of water-soluble humic organic matter in constructed wetland was biological metabolic input instead of terrigenous input; (2) in the later section of the surface flow constructed wetland, part of proteinoid substance changed into fulvic acid-like substance, which showed that the composition of dissolved organic matter and material structure tended to be stable after surface flow combined constructed wetland treatment; (3) it was of great significance that surface flow constructed wetland in structure transformation of water soluble organic matter, which could significantly improve the stability of water soluble organic matter. Surface flow+vertical flow combined constructed wetland process of dissolved organic matter had a good removal effect. PMID:26672296

  11. Modeling Escherichia coli removal in constructed wetlands under pulse loading.

    PubMed

    Hamaamin, Yaseen A; Adhikari, Umesh; Nejadhashemi, A Pouyan; Harrigan, Timothy; Reinhold, Dawn M

    2014-03-01

    Manure-borne pathogens are a threat to water quality and have resulted in disease outbreaks globally. Land application of livestock manure to croplands may result in pathogen transport through surface runoff and tile drains, eventually entering water bodies such as rivers and wetlands. The goal of this study was to develop a robust model for estimating the pathogen removal in surface flow wetlands under pulse loading conditions. A new modeling approach was used to describe Escherichia coli removal in pulse-loaded constructed wetlands using adaptive neuro-fuzzy inference systems (ANFIS). Several ANFIS models were developed and validated using experimental data under pulse loading over two seasons (winter and summer). In addition to ANFIS, a mechanistic fecal coliform removal model was validated using the same sets of experimental data. The results showed that the ANFIS model significantly improved the ability to describe the dynamics of E. coli removal under pulse loading. The mechanistic model performed poorly as demonstrated by lower coefficient of determination and higher root mean squared error compared to the ANFIS models. The E. coli concentrations corresponding to the inflection points on the tracer study were keys to improving the predictability of the E. coli removal model.

  12. Modeling Escherichia coli removal in constructed wetlands under pulse loading.

    PubMed

    Hamaamin, Yaseen A; Adhikari, Umesh; Nejadhashemi, A Pouyan; Harrigan, Timothy; Reinhold, Dawn M

    2014-03-01

    Manure-borne pathogens are a threat to water quality and have resulted in disease outbreaks globally. Land application of livestock manure to croplands may result in pathogen transport through surface runoff and tile drains, eventually entering water bodies such as rivers and wetlands. The goal of this study was to develop a robust model for estimating the pathogen removal in surface flow wetlands under pulse loading conditions. A new modeling approach was used to describe Escherichia coli removal in pulse-loaded constructed wetlands using adaptive neuro-fuzzy inference systems (ANFIS). Several ANFIS models were developed and validated using experimental data under pulse loading over two seasons (winter and summer). In addition to ANFIS, a mechanistic fecal coliform removal model was validated using the same sets of experimental data. The results showed that the ANFIS model significantly improved the ability to describe the dynamics of E. coli removal under pulse loading. The mechanistic model performed poorly as demonstrated by lower coefficient of determination and higher root mean squared error compared to the ANFIS models. The E. coli concentrations corresponding to the inflection points on the tracer study were keys to improving the predictability of the E. coli removal model. PMID:24231031

  13. 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.

  14. 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.

  15. Patterns of soil moisture and vegetation in constructed wetlands

    NASA Astrophysics Data System (ADS)

    Ursino, N.

    2009-04-01

    Early results from a new simple model for the study of eco-hydrological patterns in constructed wetland are presented. The model may simulate the case that a dominant plant tends to colonize neighbouring zones to the detriment of the other species, or that synergies between different species allow their survival under water or oxygen stress. Tasks such as of zonation and controlling invasive plants spreading by regulating water table depth and inundation timing are discussed on the base of the outcome of few numerical modelling exercises.

  16. Effects of open water on the performance of a constructed wetland for nonpoint source pollution control.

    PubMed

    Kim, H C; Yoon, C G; Son, Y K; Rhee, H P; Lee, S B

    2010-01-01

    The seasonal performance of four differently configured constructed wetland systems was compared for the treatment efficiency of nonpoint source pollution. Dead plants in the constructed wetlands increased the nitrogen removal rate during winter by providing organic carbon, which is essential for the denitrification process. However, when the wetlands released phosphorus from the dead plants, the removal rate of phosphorus decreased. After seven growing seasons, plant coverage was nearly 100%, and the dissolved oxygen (DO) concentration was lowered to 1.3-5.4 mg/L. Open-water sections were then constructed inside the wetlands, which resulted in enhanced DO concentrations as well as improved treatment efficiency of nutrients and biochemical oxygen demand (BOD). Overall, performance of the constructed wetland was improved BOD, total nitrogen, and total phosphorus with the establishment of open water sections in the constructed wetland system.

  17. 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.

  18. 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

  19. Does batch operation enhance oxidation in subsurface constructed wetlands?

    PubMed

    Stein, O R; Hook, P B; Biederman, J A; Allen, W C; Borden, D J

    2003-01-01

    Two side-by-side experimental sub-surface flow systems allowed direct comparison of wetland performance under batch and continuous-flow operation. One system consisted of microcosm "columns" operated in 20-day batch mode while the second consisted of continuous-flow "cells" operated at a five-day residence time. Both systems treated identical synthetic domestic wastewater for two years and then treated identical synthetic mine-impacted water for one year. Each system had replicates planted with Typha latifolia, Scirpus acutus and unplanted controls. Temperature was cycled annually between 4 to 24 degrees C. Results indicated that plant species, season, and mode of operation interacted strongly in controlling dynamics of COD, nitrogen species, phosphate, sulfate, and redox potentials. In batch-loaded columns, between-species differences in oxidation and COD removal were large in winter, during plant dormancy, but absent in summer; COD removal, sulfate concentration, and redox potentials were closely correlated, suggesting that variation in root-zone oxygenation due to seasonal plant growth patterns and temperature-dependent plant and microbial respiration may explain observed differences. In the continuous-flow cells, species and seasonal differences were minimal or non-existent, indicating that under continuous-flow operation plants either did not influence root zone oxidation or that this influence had no effect on wetland performance for COD and nutrient removal or sulfate reduction.

  20. Performance Evaluation of Integrated Constructed Wetland for Domestic Wastewater Treatment.

    PubMed

    Sehar, Shama; Naz, Iffat; Khan, Sumera; Naeem, Sana; Perveen, Irum; Ali, Naeem; Ahmed, Safia

    2016-03-01

    Simple, budget friendly, laboratory-scale integrated constructed wetland (ICW) was designed to assess domestic wastewater treatment performance at a loading rate of 75 mm/d, planted with native plant species: Veronica-angallis aquatica and compared with non-vegetative control system at various residence times of 4, 8, 12, 16, 20, 24, and 28 days. Results revealed that the vegetated ICW demonstrated superior performance over non-vegetated control: 69.12 vs 17.12%, 67.77 vs 16.04%, 68 vs 16.48%, 71.19 vs 6.56%, 71.54 vs 14.80%, and 72.04 vs 11.41% for total dissolved solids, total suspended solids, phosphates (PO4(-)), sulfate (SO4(-)), nitrate (NO3(-)), and nitrite (NO2(-)), respectively, at 20 days residence times. Reduction in bacterial counts (2.79 × 10(4) CFU/mL) and fecal pathogens (345.5 MPN index/100 mL) was observed in V. aquatica at 20 days residence time. Therefore, the present study highlights not only the presence of vegetation but also appropriate residence time in constructed wetlands for better performances. PMID:26931539

  1. 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.

  2. [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. PMID:25518662

  3. [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.

  4. Microbial populations and decomposition activity in three subsurface flow constructed wetlands

    SciTech Connect

    Hatano, K.; Trettin, C.C.; House, C.H.; Wollum, A.G. II

    1991-12-31

    Metabolic activity of microorganisms is the primary mechanism for organic matter degradation in constructed wetlands. However, the occurrence and abundance of different types of microorganisms responsible for degradation reactions has not been widely studied. The objective of this paper is to characterize the distribution and abundance of microorganisms in three constructed wetlands and evaluate their potent decomposition activity.

  5. Microbial populations and decomposition activity in three subsurface flow constructed wetlands

    SciTech Connect

    Hatano, K.; Trettin, C.C.; House, C.H.; Wollum, A.G. II )

    1991-01-01

    Metabolic activity of microorganisms is the primary mechanism for organic matter degradation in constructed wetlands. However, the occurrence and abundance of different types of microorganisms responsible for degradation reactions has not been widely studied. The objective of this paper is to characterize the distribution and abundance of microorganisms in three constructed wetlands and evaluate their potent decomposition activity.

  6. Influence of substrate heterogeneity on the hydraulic residence time and removal efficiency of horizontal subsurface flow constructed wetlands

    NASA Astrophysics Data System (ADS)

    Carranza-Diaz, O.; Brovelli, A.; Rossi, L.; Barry, D. A.

    2009-04-01

    Horizontal, subsurface flow constructed wetlands are wastewater treatment devices. The influent polluted water flows through a porous substrate where the contaminants are removed, for example by microbial oxidation, surface adsorption and mineral precipitation. These systems are widely used with varying degrees of success to treat municipal and agricultural contaminated waters and remove the organic carbon and nutrient load. Constructed wetlands are an appealing and promising technology, because they (i) are potentially very efficient in removing the pollutants, (ii) require only a small external energy input and (iii) require low maintenance. However, practical experience has shown that the observed purification rate is highly variable and is often much smaller than expected. One of the numerous reasons proposed to explain the variable efficiency of constructed wetlands is the existence of highly conductive zones within the porous substrate, which produce a dramatic reduction of the hydraulic residence time and therefore directly decreases the overall water purification rate. This work aims to understand quantitatively the relationship between the spatial variability in the hydraulic properties of the substrate and the effective residence time in constructed wetlands. We conducted two suites of stochastic numerical simulations, modelling the transport of a conservative tracer in a three-dimensional simulated constructed wetland in one case, and the microbial oxidation of a carbon source in the other. Within each group of simulations, different hydraulic conductivity fields were tested. These were based on a log-normal, spatially correlated random field (with exponential spatial correlation). The amount of heterogeneity was varied by changing the variance correlation length in the three directions. For each set of parameters, different realizations are considered to deduce both the expected residence time for a certain amount of heterogeneity, and its range of

  7. [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.

  8. [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.

  9. 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. PMID:26527342

  10. 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.

  11. 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...

  12. 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

  13. Effects of salinity on treatment of municipal wastewater by constructed mangrove wetland microcosms.

    PubMed

    Wu, Yan; Tam, N F Y; Wong, M H

    2008-01-01

    The effects of salinity on the removal of dissolved organic carbon and nutrients from municipal wastewater by constructed mangrove microcosms planted with Aegiceras corniculatum were investigated. During the four-month wastewater treatment, the treatment efficiency was reduced by high salinity, and the removal percentages of dissolved organic carbon, ammonia-N and inorganic N dropped from 91% to 71%, from 98% to 83% and from 78% to 56%, respectively, with salinity increasing from 0 to 30 parts per thousands (ppt). In spite of such inhibition at high salinity, 100% of the effluents discharge from the constructed mangrove microcosms still complied with the discharge standards set by the Hong Kong Government for Coastal Water Control Zones. These results suggested that constructed mangrove wetland treatment systems were promising to effectively treat municipal wastewater, even those with high salinity. In addition, the denitrification potential in soil was found to be retarded by the high salinity while mangrove plants grew best at 15 ppt salinity condition.

  14. [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

    proposed to maintain the tradeoff balance between the potential release and maximization of wetland treatment efficiency and the treated water amount, such as constructing or modifying the hydraulic structures to regulate flow amount through large ditch, redistributing water flow and increasing the water head difference between the two sides of alternate small ditches.

  15. 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.

  16. 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.

  17. 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. PMID:11804141

  18. Enhancement of azo dye Acid Orange 7 removal in newly developed horizontal subsurface-flow constructed wetland.

    PubMed

    Tee, Heng-Chong; Lim, Poh-Eng; Seng, Chye-Eng; Mohd Nawi, Mohd Asri; Adnan, Rohana

    2015-01-01

    Horizontal subsurface-flow (HSF) constructed wetland incorporating baffles was developed to facilitate upflow and downflow conditions so that the treatment of pollutants could be achieved under multiple aerobic, anoxic and anaerobic conditions sequentially in the same wetland bed. The performances of the baffled and conventional HSF constructed wetlands, planted and unplanted, in the removal of azo dye Acid Orange 7 (AO7) were compared at the hydraulic retention times (HRT) of 5, 3 and 2 days when treating domestic wastewater spiked with AO7 concentration of 300 mg/L. The planted baffled unit was found to achieve 100%, 83% and 69% AO7 removal against 73%, 46% and 30% for the conventional unit at HRT of 5, 3 and 2 days, respectively. Longer flow path provided by baffled wetland units allowed more contact of the wastewater with the rhizomes, microbes and micro-aerobic zones resulting in relatively higher oxidation reduction potential (ORP) and enhanced performance as kinetic studies revealed faster AO7 biodegradation rate under aerobic condition. In addition, complete mineralization of AO7 was achieved in planted baffled wetland unit due to the availability of a combination of aerobic, anoxic and anaerobic conditions.

  19. 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.

  20. The role of plant uptake on the removal of organic matter and nutrients in subsurface flow constructed wetlands: a simulation study.

    PubMed

    Langergraber, G

    2005-01-01

    Plants in constructed wetlands have several functions related to the treatment processes. It is generally agreed that nutrient uptake is a minor factor in constructed wetlands treating wastewater compared to the loadings applied. For low loaded systems plant uptake can contribute a significant amount to nutrient removal. The contribution of plant uptake is simulated for different qualities of water to be treated using the multi-component reactive transport module CW2D. CW2D is able to describe the biochemical elimination and transformation processes for organic matter, nitrogen and phosphorus in subsurface flow constructed wetlands. The model for plant uptake implemented describes nutrient uptake coupled to water uptake. Literature values are used to calculate potential water and nutrient uptake rates. For a constructed wetland treating municipal wastewater a potential nutrient uptake of about 1.9% of the influent nitrogen and phosphorus load can be expected. For lower loaded systems the potential uptake is significantly higher, e.g. 46% of the nitrogen load for treatment of greywater. The potential uptake rates could only be simulated for high loaded systems i.e. constructed wetlands treating wastewater. For low loaded systems the nutrient concentrations in the liquid phase were too low to simulate the potential uptake rates using the implemented model for plant uptake.

  1. Phosphorus removal in laboratory-scale unvegetated vertical subsurface flow constructed wetland systems using alum sludge as main substrate.

    PubMed

    Babatunde, A O; Zhao, Y Q

    2009-01-01

    This research has two eventual goals: (1) To optimize performance of subsurface constructed wetlands for removal of phosphorus (P) (2) To demonstrate that dewatered alum sludge (a by-product), can be reused as a constructed wetland substrate. To achieve these, alum sludge from a water treatment plant was characterized and used as main substrate in four experimental vertical sub-surface flow constructed wetland systems treating dairy farm wastewater. Results show that the alum sludge has suitable hydraulic characteristics (uniformity coefficient = 3.6) for use as a substrate, and in the batch studies, up to 48.6 mg-P was removed by 1 g of the alum sludge at a P concentration of 360 mg-P/l and a dosage of 5 g/l. Results from the experimental systems highlight the significant P removal ability of the alum sludge. However, the inclusion of pea gravel at the infiltrative surface of some of the systems had a negative effect on the P removal performance. Sequential P-fractionation results show that there was no significant increase in the easily extractable P, but for total P, there was significant increase, although this was found to decrease with depth. This study shows that the novel use of dewatered alum sludge can bring about high P removal in vertical subsurface flow constructed wetland systems.

  2. Greywater treatment by constructed wetlands in combination with TiO2-based photocatalytic oxidation for suburban and rural areas without sewer system.

    PubMed

    Li, Z; Gulyas, H; Jahn, M; Gajurel, D R; Otterpohl, R

    2003-01-01

    In this study greywater treatment through constructed wetlands and subsequently through TiO2-based photocatalytic oxidation was investigated. Through constructed wetlands treatment the organic substances have been reduced greatly. For further removal of organic substances and pathogens, a TiO2-based photocatalytic oxidation process was used subsequently. The results showed that the treated greywater through constructed wetlands and subsequent through TiO2-based photocatalytic oxidation with short irradiation time (3 hours irradiation time) met the requirements of European bathing water quality easily. Therefore, the greywater treated with the processes combination can directly be reused for non-potable purposes. Moreover, since residual organic substances through TiO2-based photocatalytic oxidation with long irradiation time can be eliminated almost totally, it is also possible that treated greywater is used for groundwater recharge as a drinking water resource.

  3. 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. PMID:25909720

  4. Identification and modelling the HRT distribution in subsurface constructed wetland.

    PubMed

    Cui, Lijuan; Zhang, Yan; Zhang, Manyin; Li, Wei; Zhao, Xinsheng; Li, Shengnan; Wang, Yifei

    2012-11-01

    This study focused on the identification of the hydrodynamics of a horizontal subsurface constructed wetland (HSSF-CW) located in Beijing wildlife rescue and rehabilitation center, Beijing. The effects of plant growth of iris tectorum on the hydrodynamic behaviours were studied and the distribution of the hydraulic residence time was simulated by several mathematical models in order to understand the fluctuations and mixing processes of pollutants in the HSSF-CW. Treatment performance of the HSSF-CW was evaluated by comparing the area-based removal rates of different pollutants. According to the results, water depth has a negative effect on the plant growth and a larger hydraulic loading rate is not conducive to the growth of wetland plants. Modelling the probability density of the residence time distribution indicated that the shorter hydraulic residence time of 10.16 hours compared with a theoretical hydraulic residence time of 12.81 hours was responsible for the lower removal efficiency of pollutants (T-P: 0.17 ± 0.04 g m(-2) day(-1), T-N: 1.10 ± 0.05 g m(-2) day(-1), PO(4)-P: 0.08 ± 0.04 g m(-2) day(-1), NH(4)-N: 0.19 ± 0.02 g m(-2) day(-1), NO(3)-N: 0.52 ± 0.03 g m(-2) day(-1), Chl_a: 18.26 ± 0.09 g m(-2) day(-1)). The results of a superposition simulation of residence time distribution indicated that the asymmetric double sigmoidal (asym2sig) model is competent at providing a reasonable match between the measured and the predicted values to some extent. Based on the good fit of the experimental datasets by the asym2sig probability density function, the mathematical expectation approximated to the actual hydraulic residence time (10.16 hours) of the HSSF-CW.

  5. 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

  6. [Evolution of Dissolved Organic Matter Properties in a Constructed Wetland of Xiao River, Hebei].

    PubMed

    Ma, Li-na; Zhang, Hui; Tan, Wen-bing; Yu, Min-da; Huang, Zhi-gang; Gao, Ru-tai; Xi, Bei-dou; He, Xiao-song

    2016-01-01

    The evolution of water DOC and COD, and the source, chemical structure, humification degree and redox of dissolved organic matter (DOM) in a constructed wetland of Xiao River, Hebei, was investigated by 3D excitation--emission matrix fluorescence spectroscopy coupled with ultraviolet spectroscopy and chemical reduction, in order to explore the geochemical processes and environmental effects of DOM. Although DOC contributes at least 60% to COD, its decrease in the constructed wetland is mainly caused by the more extensive degradation of elements N, H, S, and P than C in DOM, and 65% is contributed from the former. DOM is mainly consisted of microbial products based on proxies f470/520 and BIX, indicating that DOM in water is apparently affected by microbial degradation. The result based on PARAFAC model shows that DOM in the constructed wetland contains protein-like and humus-like components, and Fulvic- and humic-like components are relatively easier to degrade than protein-like components. Fulvic- and humic-like components undergo similar decomposition in the constructed wetland. A common source of chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) exists; both CDOM and FDOM are mainly composed of a humus-like material and do not exhibit selective degradation in the constructed wetland. The proxies E2 /E3, A240-400, r(A, C) and HIX in water have no changes after flowing into the constructed wetland, implying that the humification degree of DOM in water is hardly affected by wet constructed wetland. However, the constructed wetland environment is not only beneficial in forming the reduced state of DOM, but also facilitates the reduction of ferric. It can also improve the capability of DOM to function as an electron shuttle. This result may be related to the condition that the aromatic carbon of DOM can be stabilized well in the constructed wetland.

  7. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. 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.

  10. 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...

  11. Decreases in ammonia volatilization in response to greater plant diversity in microcosms of constructed wetlands

    NASA Astrophysics Data System (ADS)

    Luo, Bin; Ge, Ying; Han, Wenjuan; Fan, Xing; Ren, Yuan; Du, Yuanyuan; Shi, Mengmeng; Chang, Jie

    2016-10-01

    Ammonia volatilization from wastewaters with a high concentration of ammonium is a serious environmental and health problem. Constructed wetlands (CWs) are widely used for treating wastewater, and plant diversity clearly improves some functions of ecosystem such as nitrogen removal. However, whether plant diversity can affect ammonia volatilization from wastewater is still unknown. In this study, we conducted a microcosm experiment with different plant diversity treatments using four plant species. Results showed that, (1) ammonia volatilization decreased with increasing plant species richness; (2) ammonia volatilization from systems containing Rumex japonicus was lower than other systems; and (3) ammonia volatilization was affected more by species composition than species richness. This paper is the first to report that ammonia volatilization is reduced by plant diversity, and that some plant species combinations are important to reduce ammonia volatilization from CWs when treating wastewater.

  12. [Feasibility of treatment of landfill leachates by external loop three phase fluidized bed-constructed wetland system].

    PubMed

    Zhang, Jin-Sheng; Yuan, Xing-Zhong; Zeng, Guang-Ming; Dong, Bei-Bei; Liang, Yun-Shan

    2009-11-01

    In this study, the system composed with the external loop fluidized bed reactor and constructed wetland was used to treat the landfill leachate. The change of water quality for the landfill leachate treated by this system was investigated. The experimental results indicated that the COD and NH4(+) -N of the influent reduced from 4000 mg x L(-1) and 300 mg x L(-1) to 1 500 mg x L(-1) and 150 mg x L(-1) after the external loop three phase fluidized bed reactor and steady at 200 mg x L(-1) and 10 mg x L(-1) behind treated by the constructed wetland. The heavy metals of Cd, Zn, Pb were also reduced for treatment by external loop three phase fluidized bed reactor. They were steady at 0.01 mg x L(-1), 0.5 mg x L(-1), 0.1 mg x L(-1) from 0.12 mg x L(-1), 3.0 mg x L(-1), 1.4 mg x L(-1) because of the constructed wetland. We also compared the different plants for the efficiency, the results showed that whatever plants, there was little effects on the efficiency of the COD and NH4(+) -N, but the effect of heavy metal was markedness.

  13. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  15. 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

  16. Treatment of industrial effluents in constructed wetlands: challenges, operational strategies and overall performance.

    PubMed

    Wu, Shubiao; Wallace, Scott; Brix, Hans; Kuschk, Peter; Kirui, Wesley Kipkemoi; Masi, Fabio; Dong, Renjie

    2015-06-01

    The application of constructed wetlands (CWs) has significantly expanded to treatment of various industrial effluents, but knowledge in this field is still insufficiently summarized. This review is accordingly necessary to better understand this state-of-the-art technology for further design development and new ideas. Full-scale cases of CWs for treating various industrial effluents are summarized, and challenges including high organic loading, salinity, extreme pH, and low biodegradability and color are evaluated. Even horizontal flow CWs are widely used because of their passive operation, tolerance to high organic loading, and decolorization capacity, free water surface flow CWs are effective for treating oil field/refinery and milking parlor/cheese making wastewater for settlement of total suspended solids, oil, and grease. Proper pretreatment, inflow dilutions through re-circulated effluent, pH adjustment, plant selection and intensifications in the wetland bed, such as aeration and bioaugmentation, are recommended according to the specific characteristics of industrial effluents.

  17. Emission of N2O and CH4 from a constructed wetland in southeastern Norway.

    PubMed

    Søvik, A K; Kløve, B

    2007-07-15

    The Skjønhaug constructed wetland (CW) is a free surface water (FSW) wetland polishing chemically treated municipal wastewater in southeastern Norway and consists of three ponds as well as trickling, unsaturated filters with light weight aggregates (LWA). Fluxes of nitrous oxide (N(2)O) and methane (CH(4)) have been measured during the autumn, winter and summer from all three ponds as well as from the unsaturated filters. Physicochemical parameters of the water have been measured at the same localities. The large temporal and spatial variation of N(2)O fluxes was found to cover a range of -0.49 to 110 mg N(2)O-N m(-2) day(-1), while the fluxes of CH(4) was found to cover a range of -1.2 to 1900 mg m(-2) day(-1). Thus, both emission and consumption occurred. Regarding fluxes of N(2)O there was a significant difference between the summer, winter and autumn, with the highest emissions occurring during the autumn. The fluxes of CH(4) were, on the other hand, not significantly different with regard to seasons. Both the emissions of N(2)O and CH(4) were positively influenced by the amount of total organic carbon (TOC). The measured fluxes of N(2)O and CH(4) are in the same range as those reported from other CWs treating wastewater. There was an approximately equal contribution to the global warming potential from N(2)O and CH(4). PMID:17204306

  18. Treatment of industrial effluents in constructed wetlands: challenges, operational strategies and overall performance.

    PubMed

    Wu, Shubiao; Wallace, Scott; Brix, Hans; Kuschk, Peter; Kirui, Wesley Kipkemoi; Masi, Fabio; Dong, Renjie

    2015-06-01

    The application of constructed wetlands (CWs) has significantly expanded to treatment of various industrial effluents, but knowledge in this field is still insufficiently summarized. This review is accordingly necessary to better understand this state-of-the-art technology for further design development and new ideas. Full-scale cases of CWs for treating various industrial effluents are summarized, and challenges including high organic loading, salinity, extreme pH, and low biodegradability and color are evaluated. Even horizontal flow CWs are widely used because of their passive operation, tolerance to high organic loading, and decolorization capacity, free water surface flow CWs are effective for treating oil field/refinery and milking parlor/cheese making wastewater for settlement of total suspended solids, oil, and grease. Proper pretreatment, inflow dilutions through re-circulated effluent, pH adjustment, plant selection and intensifications in the wetland bed, such as aeration and bioaugmentation, are recommended according to the specific characteristics of industrial effluents. PMID:25792030

  19. Nutrient removal from piggery effluent using vertical flow constructed wetlands in southern Brazil.

    PubMed

    Sezerino, P H; Reginatto, V; Santos, M A; Kayser, K; Kunst, S; Philippi, L S; Soares, H M

    2003-01-01

    Santa Catarina State, southern Brazil, has the greatest swine breeding activities of Latin America. Generally, the piggery wastewater is treated in pond systems that are able to remove organic material according to local environmental legislation. However, these systems do not remove nitrogen and phosphorus efficiently. This work deals with a post-treatment system, using vertical flow constructed wetlands. The experiment was conducted in a swine production farm which has 45,000 animals. Although the pond system was able to partially remove the content of nutrients, their concentration in the effluent was high for environmental disposal. A four-bed vertical flow constructed wetland pilot plant, using Typha spp., was built. The pilot plant operated for 280 days for beds 2-4 (sand 2). However, the experiments with beds 1-3 (sand 1) were stopped after 111 days of operation, when a reduction in the wastewater drainage was observed. The beds with sand 2 showed a 33% COD removal, and about 49% of nitrification was observed from 111 days until the end of the operation. PO(4)-P removal was 45% with a loading rate of around 1.36 g m(-2) d(-1).

  20. 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.

  1. 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.

  2. 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. PMID:22173415

  3. 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.

  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. Effects of Road De-icing Salts in Constructed Wetlands

    NASA Astrophysics Data System (ADS)

    Silver, P.

    2005-05-01

    In November 2003, a 4-lane highway and 6 mitigation wetlands were opened across the Penn State campus, Erie, Pennsylvania. Road runoff overflows into 1 wetland (T3), and another (R3) receives salt spray and plowed snow. I have logged conductivity and temperature hourly at the sediment-water interface in R3 and T3 since January 2004, and I measure conductivity, temperature, and chironomid density biweekly in all 6 wetlands. Salinity in the wetlands that receive no salt is 0 psu. Biweekly checks of conductivity grossly underestimated winter salinities in T3 and R3. Between January and March 2004, salinity was >5 psu 5 times in R3, and >10 psu 6 times and >30 psu twice in T3. Flushing rates were similar in both wetlands, but time constants were significantly greater in T3 than R3. Salinities returned to 0 psu in both wetlands in May. Chironomid density was significantly lower in T3 than in all other wetlands in summer and autumn, long after salinities at the sediment-water interface returned to 0. Thus, chironomid densities indicated persistent biological effects of de-icers even when measurable salinities were 0 psu. Winter 2005 data show decreasing chironomid density in T3, whereas densities are increasing in the other 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. 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.

  9. [Treatment characteristics of saline domestic wastewater by constructed wetland].

    PubMed

    Gao, Feng; Yang, Zhao-Hui; Li, Chen; Jin, Wei-Hong; Deng, Yi-Bing

    2012-11-01

    A series of experiments were conducted to evaluate the feasibility of using constructed wetland (CW) to remove pollutants from saline domestic sewage. The experimental results indicated that the effects of salinity on the contaminant removal were insignificant when the influent salinities of the CWs were less than or equal to 1.5%. For the influent salinity of 0%, 0.5%, 1.0% and 1.5%, the average removal rates of the CWs were found to be above 68.3% for COD and above 66.1% for NH4(+) -N. When the influent salinity was increased to 2.0%, the individual numbers of microorganisms in the CW reduced obviously. It was similar to the change of the soil enzyme activity in the CW. Then the removal efficiency of the CW also dropped significantly. The average removal rate of COD and NH4(+) -N dropped to 52.9% and 50.3%, respectively. The effects of HRT on the treatment performance of CW under the saline condition of 1.5% were also investigated in this study. And the results showed that nitrogen removal was more greatly affected by HRT than organic matter removal. The NH4(+) -N removal efficiency in CW decreased from 65.1% -78.2% to 47.1% when the HRT of the CW varied from 3-5 d to 2 d. PMID:23323411

  10. 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.

  11. 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

  12. Bacterial communities in batch and continuous-flow wetlands treating the herbicide S-metolachlor.

    PubMed

    Elsayed, O F; Maillard, E; Vuilleumier, S; Imfeld, G

    2014-11-15

    Knowledge of wetland bacterial communities in the context of pesticide contamination and hydrological regime is scarce. We investigated the bacterial composition in constructed wetlands receiving Mercantor Gold(®) contaminated water (960 g L(-1) of the herbicide S-metolachlor, >80% of the S-enantiomer) operated under continuous-flow or batch modes to evaluate the impact of the hydraulic regime. In the continuous-flow wetland, S-metolachlor mass removal was >40%, whereas in the batch wetland, almost complete removal of S-metolachlor (93-97%) was observed. Detection of ethanesulfonic and oxanilic acid degradation products further indicated S-metolachlor biodegradation in the two wetlands. The dominant bacterial populations were characterised by terminal restriction fragment length polymorphism (T-RFLP) and 454 pyrosequencing. The bacterial profiles evolved during the first 35 days of the experiment, starting from a composition similar to that of inlet water, with the use of nitrate and to a lesser extent sulphate and manganese as terminal electron acceptors for microbial metabolism. Proteobacteria were the most abundant phylum, with Beta-, Alpha- and Gammaproteobacteria representing 26%, 19% and 17% respectively of total bacterial abundance. Bacterial composition in wetland water changed gradually over time in continuous-flow wetland and more abruptly in the batch wetland. Differences in overall bacterial water structure in the two systems were modest but significant (p=0.008), and S-metolachlor, nitrate, and total inorganic carbon concentrations correlated with changes in the bacterial profiles. Together, the results highlight that bacterial composition profiles and their dynamics may be used as bioindicators of herbicide exposure and hydraulic disturbances in wetland systems.

  13. [Construction of a landscaping-type wetland system for wastewater treatment construction of a landscaping-type wetland system for wastewater treatment and analysis of plant denitrifying effect].

    PubMed

    Chen, Ming-li; Wu, Xiao-fu; Chen, Yong-hua; Jiang, Li-juan; Ji, Zhi-hui; Ma, Qun

    2010-03-01

    A pilot landscaping-type wetland system for wastewater treatment was constructed by introduction of 15 selected ornamental plant species (including 4 terrestrial plant species). The pilot system consists of 2 sequenced treatment units and 12 sub-units, i.e., a primary treatment unit with 4 parallel cells and a secondary treatment unit with 8 subsurface flow cells. Designed experiments were conducted in the established system to investigate the characteristics of nitrogen accumulation in different plants and the contribution of plant nitrogen uptake to total nitrogen removal of the constructed wetland system. The result shows that the direct contribution by plant uptake to the total nitrogen removal is low, ca. 1%-3% within the nitrogen concentration range 37.5-55.6 mg/L in the influent. Plant uptake does not fully reflect the important role of the plant species in the constructed wetland system for wastewater treatment as the function of the plant should include further its interaction with microorganisms and wetland fillers by enhancing microbial activities and filler adsorption capacities. The plant denitrifying effect, defined as the difference in nitrogen removal rates between units with and without plants, has been used to represent the contribution in nitrogen removal due to presence of plant in the system. The plant denitrifying effect thus includes both the plant nitrogen uptake and the interaction effect of plant with microorganisms and wetland fillers, the later being found to account for more than 80% of the total nitrogen removal in the established treatment system.

  14. Potential mining of lithium, beryllium and strontium from oilfield wastewater after enrichment in constructed wetlands and ponds.

    PubMed

    Schaller, Jörg; Headley, Tom; Prigent, Stephane; Breuer, Roman

    2014-09-15

    Shortages of resources (chemical elements) used by growing industrial activities require new techniques for their acquisition. A suitable technique could be the use of wetlands for the enrichment of elements from produced water of the oil industry. Oil industries produce very high amounts of water in the course of oil mining. These waters may contain high amounts of rare elements. To our best knowledge nothing is known about the economic potential regarding rare element mining from produced water. Therefore, we estimated the amount of harvestable rare elements remaining in the effluent of a constructed wetland-pond system which is being used to treat and evaporate vast quantities of produced waters. The examined wetland system is located in the desert of the south-eastern Arabian Peninsula. This system manages 95,000 m(3) per day within 350 ha of surface flow wetlands and 350 ha of evaporation ponds and is designed to be used for at least 20 years. We found a strong enrichment of some chemical elements in the water pathway of the system (e.g. lithium up to 896 μg L(-1) and beryllium up to 139 μg L(-1)). For this wetland, lithium and beryllium are the elements with the highest economic potential resulting from a high price and load. It is calculated that after 20 years retention period 131 t of lithium and 57 t of beryllium could be harvested. This technique may also be useful for acquisition of rare earth elements. Other elements (e.g. strontium) with a high calculated load of 4500 tons in 20 years are not efficiently harvestable due to a relatively low market value. In conclusion, wetland treated waters from the oil industry offer a promising new acquisition technique for elements like lithium and beryllium.

  15. A multiple-realizations chance-constrained model for optimizing nutrient removal in constructed wetlands

    NASA Astrophysics Data System (ADS)

    Ng, Tze Ling; Eheart, J. Wayland

    2008-04-01

    High nutrient loads in surface waters are a cause of hypoxia in coastal ecosystems. Constructed wetlands offer a means of nutrient removal, but their design is complicated by environmental fluctuations. In the present work, a chance-constrained model is developed on the basis of satisfying performance constraints for a subset of the period of hydrologic and meteorological record. The model incorporates a nonsteady state wetland model and is used to determine the most cost-efficient wetland design given the nutrient removal requirements. Three candidate wetlands are considered. For two of them a comparison is made between operating the wetlands individually versus operating them concurrently. Results show that the factors limiting wetland performance are low flow availability and low inflow nutrient concentrations. Further, for the case considered, a two-wetland design is found to be more cost-effective than a single-wetland design. On average, wetlands have huge potential for nutrient removal but have a higher risk of failure than conventional treatment and could, under unfavorable conditions, be more expensive.

  16. 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.

  17. 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

  18. Can Artificial Ecosystems Enhance Local Biodiversity? The Case of a Constructed Wetland in a Mediterranean Urban Context.

    PubMed

    De Martis, Gabriele; Mulas, Bonaria; Malavasi, Veronica; Marignani, Michela

    2016-05-01

    Constructed wetlands (CW) are considered a successful tool to treat wastewater in many countries: their success is mainly assessed observing the rate of pollution reduction, but CW can also contribute to the conservation of ecosystem services. Among the many ecosystem services provided, the biodiversity of CW has received less attention. The EcoSistema Filtro (ESF) of the Molentargius-Saline Regional Natural Park is a constructed wetland situated in Sardinia (Italy), built to filter treated wastewater, increase habitat diversity, and enhance local biodiversity. A floristic survey has been carried out yearly 1 year after the construction of the artificial ecosystem in 2004, observing the modification of the vascular flora composition in time. The flora of the ESF accounted for 54% of the whole Regional Park's flora; alien species amount to 12%; taxa of conservation concern are 6%. Comparing the data in the years, except for the biennium 2006/2007, we observed a continuous increase of species richness, together with an increase of endemics, species of conservation concern, and alien species too. Once the endemics appeared, they remained part of the flora, showing a good persistence in the artificial wetland. Included in a natural park, but trapped in a sprawling and fast growing urban context, this artificial ecosystem provides multiple uses, by preserving and enhancing biodiversity. This is particularly relevant considering that biodiversity can act as a driver of sustainable development in urban areas where most of the world's population lives and comes into direct contact with nature.

  19. Can Artificial Ecosystems Enhance Local Biodiversity? The Case of a Constructed Wetland in a Mediterranean Urban Context

    NASA Astrophysics Data System (ADS)

    De Martis, Gabriele; Mulas, Bonaria; Malavasi, Veronica; Marignani, Michela

    2016-05-01

    Constructed wetlands (CW) are considered a successful tool to treat wastewater in many countries: their success is mainly assessed observing the rate of pollution reduction, but CW can also contribute to the conservation of ecosystem services. Among the many ecosystem services provided, the biodiversity of CW has received less attention. The EcoSistema Filtro (ESF) of the Molentargius-Saline Regional Natural Park is a constructed wetland situated in Sardinia (Italy), built to filter treated wastewater, increase habitat diversity, and enhance local biodiversity. A floristic survey has been carried out yearly 1 year after the construction of the artificial ecosystem in 2004, observing the modification of the vascular flora composition in time. The flora of the ESF accounted for 54 % of the whole Regional Park's flora; alien species amount to 12 %; taxa of conservation concern are 6 %. Comparing the data in the years, except for the biennium 2006/2007, we observed a continuous increase of species richness, together with an increase of endemics, species of conservation concern, and alien species too. Once the endemics appeared, they remained part of the flora, showing a good persistence in the artificial wetland. Included in a natural park, but trapped in a sprawling and fast growing urban context, this artificial ecosystem provides multiple uses, by preserving and enhancing biodiversity. This is particularly relevant considering that biodiversity can act as a driver of sustainable development in urban areas where most of the world's population lives and comes into direct contact with nature.

  20. Temperature effects on wastewater nitrate removal in laboratory-scale constructed wetlands

    SciTech Connect

    Wood, S.L.; Wheeler, E.F.; Berghage, R.D.; Graves, R.E.

    1999-02-01

    Constructed wetlands may be used for removal of high nutrient loads in greenhouse wastewater prior to discharge into the environment. Temperature affects both the physical and biological activities in wetland systems. Since nitrification and denitrification are temperature-dependent processes, effluent nitrate concentrations will fluctuate due to changes in air and wetland temperature. In a cold climate, constructed wetlands can function in a temperature-controlled, greenhouse environment year-round. This work evaluates four temperature treatments on nitrate removal rates in five planted and five unplanted laboratory-scale wetlands. Wetlands were supplied with a nutrient solution similar to the fertigation runoff solution (100 PPM nitrate-N) used in greenhouse crop production. A first-order kinetic model was used to describe experimental nitrate depletion data and to predict nitrate removal rate constants (k) in the wetlands planted with Iris pseudocoras. The negligible removal in unplanted wetlands was thought to be due to lack of carbon source in the fertigation solution. Between 19 and 23 C is planted systems, k increased from 0.062 to 0.077 h{sup {minus}1}, appeared to peak around 30 C (k = 0.184 h{sup {minus}1}), but decreased at 38 C (k = 0.099h{sup {minus}1}). Based on the Arrhenius equation, k was a first-order exponential function of temperature between 18 and 30 C in planted systems. Quantification of temperature effects on planted and unplanted laboratory-scale constructed wetlands can be sued to enhance the design and management of wastewater treatment wetlands.

  1. Performance of Free Water Surface Constructed Wetland Using Typhalatifolia and Canna Lilies for the Treatment of Domestic Wastewater.

    PubMed

    Shrikhande, Avinash N; Nema, P; Mhaisalkar, Vasant A

    2014-01-01

    Discharge of untreated wastewater or partially treated wastewater into surface water bodies or on to land is a major cause of surface and ground water pollution thereby posing health hazards. Conventional wastewater treatment is generally not preferred for small communities due to higher capital and maintenance costs and lack of skilled supervision required for operation and maintenance. A constructed wetland treatment appears to be an appropriate alternative that can be employed both in developed and developing countries. A constructed wetland system is simple to construct and operate with low cost, and hence worth considering for the treatment of municipal wastewaters, especially from small communities. In this context, the site for carrying out the studies related to wastewater treatment was chosen at Kavikulguru Institute of Technology and Science (KITS), Ramtek, Dist. Nagpur. A Free Water Surface Constructed Wetland (FWSCW) of size 22.00m x 6.50 m x 0.60m was constructed at KITS, Ramtek. The performance of FWS CW system was studied for domestic wastewater treatment with theoretical hydraulic retention times of 10 days, 7 days and 5 days. Important parameters, such as BOD5, COD, TSS, NH4-N, PO4-P, DO, pH and faecal coliforms in both raw and treated wastewaters were monitored during a macrophytes life cycle. Based on the studies, it is concluded that minimum 5 days HRT is necessary for the treatment of wastewater in FWSCW using Typhalatifolia or Canna Lilies. Typhalatifolia is better in removal of pollutants from the wastewater in comparison to Canna Lilies and hence, is recommended for use in constructed wetland. The nutrient uptake capacity of Typhalatifolia is also quite encouraging and hence has great potential for application in treating wastewater from fertilizer industry. During the application of kinetic model, the observed and predicted values in respect of BOD, TSS and NH4-N in case of Typhalatifolia and BOD, COD and TSS in case of Canna Lilies were

  2. Biogeochemical Processes Related to Metal Removal and Toxicity Reduction in the H-02 Constructed Wetland, Savannah River Site

    NASA Astrophysics Data System (ADS)

    Burgess, E. A.; Mills, G. L.; Harmon, M.; Samarkin, V.

    2011-12-01

    The H-02 wetland system was designed to treat building process water and storm water runoff from multiple sources associated with the Tritium Facility at the DOE-Savannah River Site, Aiken, SC. The wetland construction included the addition of gypsum (calcium sulfate) to foster a sulfate-reducing bacterial population. Conceptually, the wetland functions as follows: ? Cu and Zn initially bind to both dissolved and particulate organic detritus within the wetland. ? A portion of this organic matter is subsequently deposited into the surface sediments within the wetland. ? The fraction of Cu and Zn that is discharged in the wetland effluent is organically complexed, less bioavailable, and consequently, less toxic. ? The Cu and Zn deposited in the surface sediments are eventually sequestered into insoluble sulfide minerals in the wetland. Development of the H-02 system has been closely monitored; sampling began in August 2007, shortly after its construction. This monitoring has included the measurement of water quality parameters, Cu and Zn concentrations in surface water and sediments, as well as, characterization of the prokaryotic (e.g., bacterial) component of wetland biogeochemical processes. Since the beginning of the study, the mean influent Cu concentration was 31.5±12.1 ppb and the mean effluent concentration was 11.9±7.3 ppb, corresponding to an average Cu removal of 64%. Zn concentrations were more variable, averaging 39.2±13.8 ppb in the influent and 25.7±21.3 ppb in the effluent. Average Zn removal was 52%. The wetland also ameliorated high pH values associated with influent water to values similar to those measured at reference sites. Seasonal variations in DOC concentration corresponded to seasonal variations in Cu and Zn removal efficiency. The concentration of Cu and Zn in the surface layer of the sediments has increased over the lifetime of the wetland and, like removal efficiency, demonstrated seasonal variation. Within its first year, the H-02

  3. Operational, design and microbial aspects related to power production with microbial fuel cells implemented in constructed wetlands.

    PubMed

    Corbella, Clara; Guivernau, Miriam; Viñas, Marc; Puigagut, Jaume

    2015-11-01

    This work aimed at determining the amount of energy that can be harvested by implementing microbial fuel cells (MFC) in horizontal subsurface constructed wetlands (HSSF CWs) during the treatment of real domestic wastewater. To this aim, MFC were implemented in a pilot plant based on two HSSF CW, one fed with primary settled wastewater (Settler line) and the other fed with the effluent of a hydrolytic up-flow sludge blanket reactor (HUSB line). The eubacterial and archaeal community was profiled on wetland gravel, MFC electrodes and primary treated wastewater by means of 16S rRNA gene-based 454-pyrosequencing and qPCR of 16S rRNA and mcrA genes. Maximum current (219 mA/m(2)) and power (36 mW/m(2)) densities were obtained for the HUSB line. Power production pattern correlated well with water level fluctuations within the wetlands, whereas the type of primary treatment implemented had a significant impact on the diversity and relative abundance of eubacteria communities colonizing MFC. It is worth noticing the high predominance (13-16% of relative abundance) of one OTU belonging to Geobacter on active MFC of the HUSB line that was absent for the settler line MFC. Hence, MFC show promise for power production in constructed wetlands receiving the effluent of a HUSB reactor.

  4. Evaluation of clogging in planted and unplanted horizontal subsurface flow constructed wetlands: solids accumulation and hydraulic conductivity reduction.

    PubMed

    De Paoli, André Cordeiro; von Sperling, Marcos

    2013-01-01

    This study aimed to evaluate the behaviour of two horizontal subsurface flow constructed wetland units regarding solids build up and clogging of the filter medium. In order to analyse the causes of this process, which is considered the major operational problem of constructed wetlands, studies were carried out to characterize accumulated solids and hydraulic conductivity at specific points of the beds of two wetlands (planted with Typha latifolia and unplanted units) receiving effluent from an upflow anaerobic sludge blanket reactor treating sanitary sewage (population equivalent of 50 inhabitants each unit). The experiments were performed after the units were operating for 2 years and 4 months. This study presents comparative results related to the quantification and characterization of accumulated solids and hydraulic conductivity along the length and width of the filter beds. Approximately 80% of the solids found were inorganic (fixed). Near the inlet end, the rate interstitial solids/attached solids was 5.0, while in the outlet end it was reduced to 1.5. Hydraulic conductivity was lower near the inlet of the units (as expected) and, by comparing the planted wetland with the unplanted, the hydraulic conductivity was lower in the former, resulting in larger undesired surface flow.

  5. Operational, design and microbial aspects related to power production with microbial fuel cells implemented in constructed wetlands.

    PubMed

    Corbella, Clara; Guivernau, Miriam; Viñas, Marc; Puigagut, Jaume

    2015-11-01

    This work aimed at determining the amount of energy that can be harvested by implementing microbial fuel cells (MFC) in horizontal subsurface constructed wetlands (HSSF CWs) during the treatment of real domestic wastewater. To this aim, MFC were implemented in a pilot plant based on two HSSF CW, one fed with primary settled wastewater (Settler line) and the other fed with the effluent of a hydrolytic up-flow sludge blanket reactor (HUSB line). The eubacterial and archaeal community was profiled on wetland gravel, MFC electrodes and primary treated wastewater by means of 16S rRNA gene-based 454-pyrosequencing and qPCR of 16S rRNA and mcrA genes. Maximum current (219 mA/m(2)) and power (36 mW/m(2)) densities were obtained for the HUSB line. Power production pattern correlated well with water level fluctuations within the wetlands, whereas the type of primary treatment implemented had a significant impact on the diversity and relative abundance of eubacteria communities colonizing MFC. It is worth noticing the high predominance (13-16% of relative abundance) of one OTU belonging to Geobacter on active MFC of the HUSB line that was absent for the settler line MFC. Hence, MFC show promise for power production in constructed wetlands receiving the effluent of a HUSB reactor. PMID:26253894

  6. Application of vertical flow constructed wetland in treatment of heavy metals from pulp and paper industry wastewater.

    PubMed

    Arivoli, A; Mohanraj, R; Seenivasan, R

    2015-09-01

    The paper production is material intensive and generates enormous quantity of wastewater containing organic pollutants and heavy metals. Present study demonstrates the feasibility of constructed wetlands (CWs) to treat the heavy metals from pulp and paper industry effluent by using vertical flow constructed wetlands planted with commonly available macrophytes such as Typha angustifolia, Erianthus arundinaceus, and Phragmites australis. Results indicate that the removal efficiencies of the planted CWs for iron, copper, manganese, zinc, nickel, and cadmium were 74, 80, 60, 70, 71, and 70 %, respectively. On the other hand, the removal efficiency of the unplanted system was significantly lower ranging between 31 and 55 %. Among the macrophytes, T. angustifolia and E. arundinaceus exhibited comparatively higher bioconcentration factor (10(2) to 10(3)) than P. australis.

  7. 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.

  8. 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.

  9. 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. PMID:23064246

  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. A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation.

    PubMed

    Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Hu, Zhen; Liang, Shuang; Fan, Jinlin; Liu, Hai

    2015-01-01

    Constructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades. CWs offer a land-intensive, low-energy, and less-operational-requirements alternative to conventional treatment systems, especially for small communities and remote locations. However, the sustainable operation and successful application of these systems remains a challenge. Hence, this paper aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development on their sustainable design and operation for wastewater treatment. Firstly, a brief summary on the definition, classification and application of current CWs was presented. The design parameters and operational conditions of CWs including plant species, substrate types, water depth, hydraulic load, hydraulic retention time and feeding mode related to the sustainable operation for wastewater treatments were then discussed. Lastly, future research on improving the stability and sustainability of CWs were highlighted.

  12. A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation.

    PubMed

    Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Hu, Zhen; Liang, Shuang; Fan, Jinlin; Liu, Hai

    2015-01-01

    Constructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades. CWs offer a land-intensive, low-energy, and less-operational-requirements alternative to conventional treatment systems, especially for small communities and remote locations. However, the sustainable operation and successful application of these systems remains a challenge. Hence, this paper aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development on their sustainable design and operation for wastewater treatment. Firstly, a brief summary on the definition, classification and application of current CWs was presented. The design parameters and operational conditions of CWs including plant species, substrate types, water depth, hydraulic load, hydraulic retention time and feeding mode related to the sustainable operation for wastewater treatments were then discussed. Lastly, future research on improving the stability and sustainability of CWs were highlighted. PMID:25453440

  13. Constructed wetland as an ecotechnological tool for pollution treatment for conservation of Ganga river.

    PubMed

    Rai, U N; Tripathi, R D; Singh, N K; Upadhyay, A K; Dwivedi, S; Shukla, M K; Mallick, S; Singh, S N; Nautiyal, C S

    2013-11-01

    With aim to develop an efficient and ecofriendly approach for on-site treatment of sewage, a sub-surface flow constructed wetland (CW) has been developed by raising potential aquatic macrophytes; Typha latifolia, Phragmites australis, Colocasia esculenta, Polygonum hydropiper, Alternanthera sessilis and Pistia stratoites in gravel as medium. Sewage treatment potential of CW was evaluated by varying retention time at three different stages of plant growth and stabilization. After 6 months, monitoring of fully established CW indicated reduction of 90%, 65%, 78%, 84%, 76% and 86% of BOD, TSS, TDS, NO3-N, PO4-P and NH4-N, respectively in comparison to inlet after 36 h of retention time. Sewage treatment through CW also resulted in reduction of heavy metal contents. Thus, CW proved an effective method for treatment of wastewater and may be developed along river Ganga stretch as an alternative technology. Treated water may be drained into river to check further deterioration of Ganga water quality. PMID:24080292

  14. Constructed wetland as an ecotechnological tool for pollution treatment for conservation of Ganga river.

    PubMed

    Rai, U N; Tripathi, R D; Singh, N K; Upadhyay, A K; Dwivedi, S; Shukla, M K; Mallick, S; Singh, S N; Nautiyal, C S

    2013-11-01

    With aim to develop an efficient and ecofriendly approach for on-site treatment of sewage, a sub-surface flow constructed wetland (CW) has been developed by raising potential aquatic macrophytes; Typha latifolia, Phragmites australis, Colocasia esculenta, Polygonum hydropiper, Alternanthera sessilis and Pistia stratoites in gravel as medium. Sewage treatment potential of CW was evaluated by varying retention time at three different stages of plant growth and stabilization. After 6 months, monitoring of fully established CW indicated reduction of 90%, 65%, 78%, 84%, 76% and 86% of BOD, TSS, TDS, NO3-N, PO4-P and NH4-N, respectively in comparison to inlet after 36 h of retention time. Sewage treatment through CW also resulted in reduction of heavy metal contents. Thus, CW proved an effective method for treatment of wastewater and may be developed along river Ganga stretch as an alternative technology. Treated water may be drained into river to check further deterioration of Ganga water quality.

  15. 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.

  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. Slag columns for upgrading phosphorus removal from constructed wetland effluents.

    PubMed

    Chazarenc, F; Brisson, J; Comeau, Y

    2007-01-01

    The current best option to upgrade constructed wetlands (CWs) for phosphorus (P) retention, in terms of efficiency, cost and simplicity, consists in using media having a strong P affinity. The media can be used either in the planted beds or in a filtration system downstream of the beds. The use of slag filters was shown to be efficient for removing P from wastewater as it represented a slow release source of calcium and hydroxide, favouring the formation of hydroxyapatite. Our study aimed at maximising the P retention capacity of slag filters located at the outlet of CWs since electric arc furnace slag has been shown to inhibit the growth of macrophytes when used in the filtration matrix. Bench-scale columns (Vtot = 6.2 L) filled with various combinations of filter media (slag, granite, limestone) of different sizes (2-5, 5-10, 10-20 mm) were fed on-site during four months with a CW effluent (in mg/L: 30 COD, 30 TSS, 10 Pt). Results showed that the best media combination enabling the maximum o-PO4 retention (more than 80% removal without clogging) consisted in a series of a ternary mix column (slag 5-10 mm, granite 2-5 mm, limestone 5-10 mm) followed by a slag column (slag 5-10 mm). Pilot scale columns (Vtot = 300 L), filled with the best media combination, were installed at the outlet of a 28 m2 CW. These columns showed more than 75% removal efficiency during one year and were designed to be easily replaced each year.

  18. Performance of a vertical subsurface flow (VSF) wetland treatment system using woodchips to treat livestock stormwater.

    PubMed

    Niu, Siping; Guerra, Heidi B; Chen, Yaoping; Park, Kisoo; Kim, Youngchul

    2013-08-01

    This study was conducted to develop a vertical subsurface flow (VSF) wetland remediation system packed with woodchips to control stormwater pollution arising from livestock agriculture. Three lab-scale VSF wetlands were operated with recirculation during the interval (Δ) between storms as 2, 4 and 8 days, respectively. The fed water was 100% recirculated one time per 24 h; the recirculation frequency was 1, 3 and 7 times at Δ of 2, 4 and 8 days, respectively. The constructed wetland systems proved to be effective in reducing total suspended solid (TSS), but also had potential for increasing TSS in the effluent due to the properties of the woodchips. The release of organic matter, especially in the dissolved form, occurred during the initial 60 days. The removal efficiencies of total nitrogen (TN) were 26.2%, 34.1% and 50.0% at Δ of 2, 4 and 8 days, respectively. Nitrification was promoted by the abundant oxygen supplied when the water in wetland was recirculated and fed into the wetland. Denitrification was stable and effective due to the availability of carbon sources. The influent total phosphorus (TP) was reduced from an average of 2.05 mg L(-1) to 1.79 mg L(-1), 1.36 mg L(-1) and 0.86 mg L(-1) at Δ as 2, 4 and 8 days, respectively. The result shows that woodchips can be used as substrate material for VSF wetland treatment systems to control nutrient influx from livestock stormwater.

  19. Constructed wetlands for sewage effluent treatment and mosquito larvae at two sites in subtropical Australia.

    PubMed

    Dale, Pat E R; Greenway, Margaret; Chapman, Heather; Breitfuss, Mark J

    2007-06-01

    This study of 2 wetlands in subtropical Australia, constructed to treat sewage effluent, examined the relationships between dips positive for mosquito larvae and water quality, operational status of the system, vegetation, and nontarget macroinvertebrates. One site is inland and the other is close to the coast. Larvae of disease vector mosquitoes were present at various times in the wetlands, especially in summer and autumn. The proportion of early instars (1st and 2nd) was greater than that of later ones (3rd and 4th). Dissolved oxygen was negatively, and temperature was positively, associated with the proportion of dips containing larvae. For the coastal site we noted that larvae were more common during draw-down of water for maintenance and also as the system started to come online. Vegetation associated with larvae included dense Typha orientalis and algae. Where there were several types of plants, such as at the coastal site, plant density and water depth were not significantly related to larval presence. Where there were several types of macroinvertebrates there were fewer dips positive for larvae. To provide water treatment capacity and minimal mosquito production we concluded that design should include a variety of plant types, discouraging low dissolved oxygen (for example, by aeration) and ongoing maintenance should be carried out in winter or spring, when mosquitoes are fewer than in summer.

  20. Adaptive neuro-fuzzy inference system for real-time monitoring of integrated-constructed wetlands.

    PubMed

    Dzakpasu, Mawuli; Scholz, Miklas; McCarthy, Valerie; Jordan, Siobhán; Sani, Abdulkadir

    2015-01-01

    Monitoring large-scale treatment wetlands is costly and time-consuming, but required by regulators. Some analytical results are available only after 5 days or even longer. Thus, adaptive neuro-fuzzy inference system (ANFIS) models were developed to predict the effluent concentrations of 5-day biochemical oxygen demand (BOD5) and NH4-N from a full-scale integrated constructed wetland (ICW) treating domestic wastewater. The ANFIS models were developed and validated with a 4-year data set from the ICW system. Cost-effective, quicker and easier to measure variables were selected as the possible predictors based on their goodness of correlation with the outputs. A self-organizing neural network was applied to extract the most relevant input variables from all the possible input variables. Fuzzy subtractive clustering was used to identify the architecture of the ANFIS models and to optimize fuzzy rules, overall, improving the network performance. According to the findings, ANFIS could predict the effluent quality variation quite strongly. Effluent BOD5 and NH4-N concentrations were predicted relatively accurately by other effluent water quality parameters, which can be measured within a few hours. The simulated effluent BOD5 and NH4-N concentrations well fitted the measured concentrations, which was also supported by relatively low mean squared error. Thus, ANFIS can be useful for real-time monitoring and control of ICW systems. PMID:25607665

  1. Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands.

    PubMed

    Seeger, Eva M; Kuschk, Peter; Fazekas, Helga; Grathwohl, Peter; Kaestner, Matthias

    2011-12-01

    In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m(2)/d, 97/112 mg/m(2)/d, and 1167/1342 mg/m(2)/d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique.

  2. 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. PMID:14621175

  3. 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

  4. 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. PMID:24027589

  5. 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.

  6. 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. PMID:20656329

  7. 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.

  8. Design of pilot-scale constructed wetlands for tertiary treatment of refinery effluent

    SciTech Connect

    Dorn, P.B.; Vergel, N.R.; Hawkins, W.B.; Dunn, A.; Rodgers, J.H. Jr.

    1994-12-31

    Two pilot-scale constructed wetlands (4:1 length:width aspect) were designed for tertiary treatment of refinery effluent. As requirements for removal of contaminants from NPDES effluents become more stringent, cost-effective technological approaches are needed to achieve the necessary treatment levels and be efficient, effective and low maintenance. The fundamental design of these constructed wetlands was based on biogeochemical principles that regulate the fate and persistence of the targeted elements (Cu, Zn, Pb). In order to maximize opportunities to learn more about the internal function of the wetlands, they were built to operate in series or in parallel permitting hydraulic retention times of 24 to 48 hours. The wetlands were lined with {approximately}76 cm of compacted clay as well as a 30 mil polyethylene liner. The hydrosoil selected for use in the constructed wetlands is 74.1% sand, 25.6% silt, 0.3% clay. Based on laboratory studies, this hydrosoil achieves a redox of 250 to {approximately}300 mv and a pH of 7.5 in the presence of Scirpus californicus. These conditions should enhance the ability of the constructed wetlands to retain and sequester the target elements and control chronic toxicity from the effluent.

  9. 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.

  10. Treatment and utilization of septic tank effluent using vertical-flow constructed wetlands and vegetable hydroponics.

    PubMed

    Cui, Li-Hua; Luo, Shi-Ming; Zhu, Xi-Zhen; Liu, Ying-Hu

    2003-01-01

    Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD5, SS, TN and TP were 71.4%, 97.5%, 96.9%, 86.3%, and 87.4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%-90% and 85%-96%, respectively.

  11. 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.

  12. Pilot-scale constructed wetlands for tertiary treatment of refinery effluent

    SciTech Connect

    Hawkins, W.B.; Dunn, A.W.; Rodgers, J.H. Jr.; Dorn, P.B.

    1995-12-31

    Two pilot-scale wetlands were designed and constructed for tertiary treatment of refinery effluent with the goal of removing Cu, Pb, and Zn. The wetlands were built to operate in series or in parallel, with hydraulic retention times of 24 and 48 hours, respectively. The wetlands were lined with a 76 cm layer of compacted clay which is covered with a non-porous 60-mil polyethylene liner. The hydrosoil selected for use in the constructed wetlands was an alluvial sediment consisting of 74.1% sand, 25.6% silt, and 0.3% clay. Scirpus californicus (Giant Bulrush) was planted in both wetlands with an average initial plant density of 9 plants per m{sup 2} and average initial heights of 0.3 m. After six months of wetland operation, the desired design characteristics have been achieved and have aided in metal removals. The hydrosoil developed an average redox potential of {minus}170 mV and a ph of 7.0. S. californicus increased to an average density of 42 plants per m{sup 2} and grew to an average height of 2.7 m. These wetland characteristics have resulted in removals of approximately 67% of the Cu, 89% of the Pb, and 98% of the Zn from the refinery effluent in preliminary monitoring. Additional studies to evaluate operating efficiencies under different conditions are in progress.

  13. 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.

  14. 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.

  15. 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.

  16. Suspended particle and pathogen peak discharge buffering by a surface-flow constructed wetland.

    PubMed

    Mulling, Bram T M; van den Boomen, Rob M; van der Geest, Harm G; Kappelhof, Joost W N M; Admiraal, Wim

    2013-03-01

    Constructed wetlands (CWs) have been shown to improve the water quality of treated wastewater. The capacity of CWs to reduce nutrients, pathogens and organic matter and restore oxygen regime under normal operating conditions cannot be extrapolated to periods of incidental peak discharges. The buffering capacity of CWs during peak discharges is potentially a key factor for water quality in the receiving waters. Therefore, the aim of the present study was to investigate the behaviour of peak discharges of suspended particles, (associated) physiochemical parameters and pathogenic organisms from a wastewater treatment plant (WWTP) in a full scale constructed wetland (CW). By mixing clarified water and sludge rich water from the settlement tank of the WWTP, the suspended particle concentration was increased for 8 h from ± 3.5 to ± 230 mg L(-1), and discharged into a full scale horizontal surface flow constructed wetland. An increase of suspended particle concentration following the peak discharge concurred with increases in turbidity and oxygen demand, total nutrient load (nitrogen, phosphorus and carbon) and pathogens (Escherichia coli and Enterococci). Temperature, pH, conductivity and dissolved nutrient concentrations (nitrogen, phosphorus and carbon) were however unaffected by the initial peak discharge. After retention in the unvegetated ponds (the first CW compartment) the applied suspended particle peak with a total load of 86.2 kg was reduced by >99%. Similar peak buffering was observed for the turbidity, oxygen demand and settable volume. Simultaneously dissolved nutrient concentrations increased, indicating partial mineralization of the suspended particles during retention in the unvegetated ponds. The peak buffering of pathogens was lower (40-84%), indicating differences in removal processes between other suspended particles and pathogens. The results indicated that the suspended particles were probably mostly removed by sedimentation and mineralization

  17. Fecal coliform removal in a lightly loaded surface-flow constructed treatment wetland polishing agricultural runoff.

    PubMed

    Beutel, Marc W; Whritenour, Victoria; Brouillard, Elaine

    2013-01-01

    Constructed treatment wetlands can be an effective and sustainable method to remove pathogens that pose health risks from agricultural runoff. This study evaluated the removal of fecal coliform (FC) from agricultural runoff in a lightly loaded surface-flow treatment wetland prior to discharge to the Yakima River, Washington State, USA. The 1.6 ha system consisted of a sedimentation basin (1.4 d hydraulic retention time) followed by two wetlands (5-6 d hydraulic retention time). FC in inflow ranged from 100 to 1,000 cfu/100 mL. Mean annual FC log-removal in the sedimentation basin was 0.66 ± 0.17 (mean plus/minus standard deviation; n = 7). However, there was a comparable production of FC within the two wetlands where annual log-removal averaged -0.71 ± 0.39 in the north wetland and -0.57 ± 0.17 in the south wetland. FC removal in the sedimentation basin weakly correlated with turbidity removal (R(2) = 0.13, p < 0.01, n = 61), suggesting that settling was an important FC loss mechanism. FC removal in the wetlands negatively correlated with temperature (R(2) = 0.27-0.33, p < 0.01, n = 26) indicating that survival and/or reproduction was an important FC production mechanism. Muskrat colonization in the wetlands in 2007 and 2008 corresponded with a marked increase in FC in wetland outflow. Results suggest that, regardless of the presence of muskrats, sedimentation basins alone are more effective than a combined sedimentation basin-wetland system in removing FC from dilute agricultural runoff.

  18. Large-scale constructed wetlands for nutrient removal from stormwater runoff: An everglades restoration project

    NASA Astrophysics Data System (ADS)

    Guardo, Mariano; Fink, Larry; Fontaine, Thomas D.; Newman, Susan; Chimney, Michael; Bearzotti, Ronald; Goforth, Gary

    1995-11-01

    The South Florida Water Management District (SFWMD) constructed a wetland south of Lake Okeechobee to begin the process of removing nutrients (especially phosphorus) from agricultural stormwater runoff entering the Everglades. The project, called the Everglades Nutrient Removal (ENR) project, is a prototype for larger, similarly constructed wetlands that the SFWMD will build as part of the Everglades restoration program. This innovative project is believed to be one of the largest agricultural stormwater cleanup projects in the United States, if not in the world. This publication describes the ENR project's design, construction, and proposed operation, as well as the proposed research program to be implemented over the next few years.

  19. 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)

  20. Higher diversity of ammonia/ammonium-oxidizing prokaryotes in constructed freshwater wetland than natural coastal marine wetland.

    PubMed

    Wang, Yong-Feng; Gu, Ji-Dong

    2013-08-01

    Anaerobic ammonium-oxidizing (anammox) bacteria, aerobic ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) are three groups of ammonium/ammonia-oxidizing prokaryotes (AOPs) that are involved in the nitrogen cycle. This research compared the AOP communities in a constructed freshwater wetland with a natural coastal marine wetland in the subtropical Hong Kong. Both vegetated/rhizosphere and nonvegetated sediments were investigated to identify the effects of different macrophytes on the AOP communities. The polymerase chain reaction (PCR)-amplified gene fragments of 16S rRNA and archaeal and bacterial amoA (encoding the ammonia monooxygenase alpha subunit) were applied as molecular biomarkers to analyze the AOPs' phylogeny and diversity. Quantitative PCR was used to determine the abundances of AOPs in the sediments. The results showed that the relatively more heterogeneous freshwater wetland contained a broader range of phylotypes, higher diversity, more complex community structures, and more unevenly distributed abundances of AOPs than the coastal wetland. The effects of vegetation on the community structures of AOPs were plant-specific. The exotic Typha angustifolia affected the community structures of all AOPs and enhanced their abundances in the rhizosphere region. Both Phragmites australis and Cyperus malaccensis showed some effects on the community structures of AOB, but minimal effects on those of anammox bacteria or AOA. Kandelia obovata had almost no detectable effect on all AOPs due to their smaller size. This study suggested that the freshwater and coastal marine wetlands may have different contributions to the inorganic N removal due to the variations in AOP communities and plant types. PMID:23053083

  1. [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.

  2. Characteristics and stabilities of residues from the Wheal Jane constructed wetlands.

    PubMed

    Swash, P M; Monhemius, A J

    2005-02-01

    The characteristics and solubilities of residues formed during effluent treatment at the Wheal Jane constructed wetland facility in Cornwall, UK are described. The constructed wetland treats an acidic (pH 3 to 4) mine discharge enriched in iron (<100 mg/l), zinc (<80 mg/l), manganese (<20 mg/l) and arsenic (<2 mg/l). The processing strategy adopted at the site is to remove elements selectively from the mine water in distinct unit process operations and concentrate the iron and base metals into residues within the circuits. Solubility tests conducted on the materials from the aerobic and anaerobic cells attempt to simulate future possible leaching processes within landfill sites used for ultimate disposal. The tests used in the evaluation included TCLP, MARG, washing and column leaching. The aerobic solids overall have very low solubilities which are well below the TCLP thresholds for As, Cd and Pb. The TCLP results for these toxic elements are supported by the washing and column test work. The anaerobic substrates are carbonaceous in nature, composed of straw, wood pulp and manure. They contain minimal amounts of toxic compounds and are considered to be less of a disposal problem. Ochre precipitated at a pH of 3-4 in the aerobic cells contains significant concentrations of arsenic (>0.1%). This element is carcinogenic, and such residues are classified as hazardous waste under current UK landfill regulations. This classification does not take into consideration the solubility of the material but is based solely on the bulk chemical composition. PMID:15680630

  3. BPA and NP removal from municipal wastewater by tropical horizontal subsurface constructed wetlands.

    PubMed

    Toro-Vélez, A F; Madera-Parra, C A; Peña-Varón, M R; Lee, W Y; Bezares-Cruz, J C; Walker, W S; Cárdenas-Henao, H; Quesada-Calderón, S; García-Hernández, H; Lens, P N L

    2016-01-15

    It has been recognized that numerous synthetic compounds like Bisphenol A (BPA) and nonylphenols (NP) are present in effluents from wastewater treatment plants (WWTP) at levels of parts per billion (μg L(-1)) or even parts per trillion (ng L(-1)) with a high potential to cause endocrine disruption in the aquatic environment. Constructed wetlands (CW) are a cost-effective wastewater treatment alternative with promising performance to treat these afore mentioned compounds. This research was aimed to evaluate the efficacy of CW treatment of WWTP effluent for mitigating the effects endocrine disrupting compounds (EDCs). This research goal was accomplished by (1) quantifying the removal of BPA and NP in CWs; (2) isolating CW fungal strains and testing for laccase production; and (3) performing endocrine disruption (reproduction) bioassays using the fruit fly Drosophila melanogaster. Three pilot scale horizontal subsurface flow constructed wetlands (HSSF-CW) were operated for eight weeks: one planted with Phragmites australis; one planted with Heliconia psitacorum; and one unplanted. The Heliconia CW showed a removal efficiency of 73.3(± 19%) and 62.8(± 20.1%) for BPA and NP, respectively; while the Phragmites CW demonstrated a similar removal for BPA (70.2 ± 27%) and lower removal efficiency for NP 52.1(± 37.1%).The unplanted CW achieved 62.2 (± 33%) removal for BPA and 25.3(± 37%) removal for NP. Four of the eleven fungal strains isolated from the Heliconia-CW showed the capacity to produce laccase. Even though complete removal of EDCs was not achieved by the CWs, the bioassay confirmed a significant improvement (p < 0.05) in fly viability for all CWs, with Heliconia sp. being the most effective at mitigating adverse effects on first and second generational reproduction. This study showed that a CW planted with a native Heliconia sp. CW demonstrated a higher removal of endocrine disrupting compounds and better mitigation of reproductive disruption in the

  4. 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.

  5. Combined industrial wastewater treatment in anaerobic bioreactor posttreated in constructed wetland.

    PubMed

    Zeb, Bibi Saima; Mahmood, Qaisar; Jadoon, Saima; Pervez, Arshid; Irshad, Muhammad; Bilal, Muhammad; Bhatti, Zulfiqar Ahmad

    2013-01-01

    Constructed wetland (CW) with monoculture of Arundo donax L. was investigated for the posttreatment of anaerobic bioreactor (ABR) treating combined industrial wastewater. Different dilutions of combined industrial wastewater (20, 40, 60, and 80) and original wastewater were fed into the ABR and then posttreated by the laboratory scale CW. The respective removal efficiencies of COD, BOD, TSS, nitrates, and ammonia were 80%, 78-82%, 91.7%, 88-92%, and 100% for original industrial wastewater treated in ABR. ABR was efficient in the removal of Ni, Pb, and Cd with removal efficiencies in the order of Cd (2.7%) > Ni (79%) > Pb (85%). Posttreatment of the ABR treated effluent was carried out in lab scale CW containing A. donax L. CW was effective in the removal of COD and various heavy metals present in ABR effluents. The posttreatment in CW resulted in reducing the metal concentrations to 1.95 mg/L, 0 mg/L, and 0.004 mg/L for Ni, Pb, and Cd which were within the permissible water quality standards for industrial effluents. The treatment strategy was effective and sustainable for the treatment of combined industrial wastewater.

  6. Polishing domestic wastewater on a subsurface flow constructed wetland: organic matter removal and microbial monitoring.

    PubMed

    Aguiar-Pinto Mina, I; Costa, M; Matos, A; Sousa Coutinho Calheiros, C; Castro, P M L

    2011-01-01

    Microbial monitoring of constructed wetlands (CWs) treating domestic wastewater is generally scarce, despite the need of more knowledge about its biocenosis. The sanitation quality of a wastewater treated in a CW is a crucial aspect, mainly when the receiving water body is used as a swimming and/or recreation area. The present study was carried out in a horizontal subsurface flow CWplanted with Phragmites australis receiving pre-treated domestic wastewater (mean flow 50 m3 day(-1)), from a population of about 300 inhabitants. The monitoring programme undertaken during the first year operation, revealed removal efficiencies of 61% BOD5, 44% COD, and 65% TSS for inlet water with ca. 90 mg L(-1) BOD5, 157 mg L(-1) COD, and 17 mg L(-1) TSS. Total Coliform (TC) and Faecal Coliform (FC) bacteria were removed from wastewater (mean inlet values of 5 x 10(6) CFU 100 mL(-1) TC and of 9 x 10(5) CFU 100 mL(-1) FC), with efficiencies of 92 and 97%, respectively. The dynamics of microbial communities established in the system assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), had revealed a high bacterial diversity within the system, with no relevant differences in composition at the CW inlet and outlet but exhibiting temporal differences in bacterial communities. PMID:21972563

  7. Combined Industrial Wastewater Treatment in Anaerobic Bioreactor Posttreated in Constructed Wetland

    PubMed Central

    Zeb, Bibi Saima; Mahmood, Qaisar; Jadoon, Saima; Pervez, Arshid; Irshad, Muhammad; Bilal, Muhammad; Bhatti, Zulfiqar Ahmad

    2013-01-01

    Constructed wetland (CW) with monoculture of Arundo donax L. was investigated for the posttreatment of anaerobic bioreactor (ABR) treating combined industrial wastewater. Different dilutions of combined industrial wastewater (20, 40, 60, and 80) and original wastewater were fed into the ABR and then posttreated by the laboratory scale CW. The respective removal efficiencies of COD, BOD, TSS, nitrates, and ammonia were 80%, 78–82%, 91.7%, 88–92%, and 100% for original industrial wastewater treated in ABR. ABR was efficient in the removal of Ni, Pb, and Cd with removal efficiencies in the order of Cd (2.7%) > Ni (79%) > Pb (85%). Posttreatment of the ABR treated effluent was carried out in lab scale CW containing A. donax L. CW was effective in the removal of COD and various heavy metals present in ABR effluents. The posttreatment in CW resulted in reducing the metal concentrations to 1.95 mg/L, 0 mg/L, and 0.004 mg/L for Ni, Pb, and Cd which were within the permissible water quality standards for industrial effluents. The treatment strategy was effective and sustainable for the treatment of combined industrial wastewater. PMID:24396832

  8. The effect of the scale of horizontal subsurface flow constructed wetlands on flow and transport parameters.

    PubMed

    Suliman, F; French, H; Haugen, L E; Kløve, B; Jenssen, P

    2005-01-01

    Horizontal subsurface flow constructed wetlands have proven their efficiency in treating wastewater and removing the pollutants of concern. Treatment efficiency depends on the wastewater residence time, which is a function of the hydraulic loading and the physical conditions of the constructed filter system, which can be described with effective parameters such as: hydraulic conductivity, porosity, dispersivity etc. Because spatial variability is often scale dependent, these effective parameters may be affected by the scale of the system being studied. In this paper the results of tracer experiments in constructed filters using saturated horizontal flow at three scales (small and medium lab scales and full-scale system) using the same filter media is reported. Light-weight aggregate (filter media termed Filtralite-P) was used at all scales. Increasing the scale was associated with increasing dispersivity, meanwhile hydraulic conductivity experienced dramatic reduction and variation by increasing the examined scale. Observed changes in the hydraulic parameters indicate that heterogeneity at different scales should be taken into account when the performance of LWA filters are evaluated from small-scale experiments. PMID:16042266

  9. Plant and Invertebrate Community Changes Caused by Flood-Pulsing in a Constructed Riparian Wetland

    NASA Astrophysics Data System (ADS)

    Caiazza, M. K.; Nieset, J. E.; Romito, A.; de Szalay, F. A.

    2005-05-01

    In 2002, Kent State University constructed a research facility that includes ten independently flooded wetland basins (10 m X 20 m) along a second order creek. We tested the effects of flood-pulsing on the wetland biota by allowing 5 basins (flood-pulse wetlands) to fluctuate with creek water levels to simulate floodplain marshes, and maintaining 5 basins (static wetlands) at constant water levels. We sampled emergent plants and aquatic invertebrates in 2003 and 2004. Abiotic conditions were different between treatments. We collected 83 plant species, and flood pulsing had strong effects on plant communities. Mean species richness and plant cover were higher in static wetlands, and Sorensen's similarity indices between habitat types decreased over time. Plant biomass increased in all wetlands from 2003 to 2004, but mean biomass was not different between treatments. Many dominant plant species were affected by the flood pulsing treatment. Wetland invertebrate communities were diverse (47 taxa), but we detected few responses. Total abundance, species richness, and numbers of most dominant species were not different between treatments. These results indicate that flood-pulsing acted as a stressor on emergent plant communities, but did not strongly impact aquatic macroinvertebrates.

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:27173842

  14. Effectiveness of Rice Agricultural Waste, Microbes and Wetland Plants in the Removal of Reactive Black-5 Azo Dye in Microcosm Constructed Wetlands.

    PubMed

    Saba, Beenish; Jabeen, Madeeha; Khalid, Azeem; Aziz, Irfan; Christy, Ann D

    2015-01-01

    Azo dyes are commonly generated as effluent pollutants by dye using industries, causing contamination of surface and ground water. Various strategies are employed to treat such wastewater; however, a multi-faceted treatment strategy could be more effective for complete removal of azo dyes from industrial effluent than any single treatment. In the present study, rice husk material was used as a substratum in two constructed wetlands (CWs) and augmented with microorganisms in the presence of wetland plants to effectively treat dye-polluted water. To evaluate the efficiency of each process the study was divided into three levels, i.e., adsorption of dye onto the substratum, phytoremediation within the CW and then bioremediation along with the previous two processes in the augmented CW. The adsorption process was helpful in removing 50% dye in presence of rice husk while 80% in presence of rice husk biocahr. Augmentation of microorganisms in CW systems has improved dye removal efficiency to 90%. Similarly presence of microorganisms enhanced removal of total nitrogen (68% 0 and Total phosphorus (75%). A significant improvement in plant growth was also observed by measuring plant height, number of leaves and leave area. These findings suggest the use of agricultural waste as part of a CW substratum can provide enhanced removal of textile dyes.

  15. Long-term efficiency and stability of wetlands for treating wastewater of a lead/zinc mine and the concurrent ecosystem development.

    PubMed

    Yang, B; Lan, C Y; Yang, C S; Liao, W B; Chang, H; Shu, W S

    2006-10-01

    A constructed wetland system in Guangdong Province, South of China has been used for treating Pb/Zn mine discharge since 1985. The performance in the purification of the mine discharge and the concurrent ecosystem development within the system during the period of 1985-2000 has been studied. The untreated wastewater contained rather high concentrations of cadmium (Cd) (0.05 mg L(-1)), lead (Pb) (11.5 mg L(-1)), and zinc (Zn) (14.5 mg L(-1)), which greatly exceed the upper limits for industrial wastewater discharge in China. The constructed wetland system effectively removed Cd by 94.00%, Pb by 99.04%, Zn by 97.30%, and total suspended solids (TSS) by 98.95% from the mine discharge over a long period (over 16 years) leading to significant improvement in water quality; it was also found that there were no significantly annual or monthly variations in pH values, As, Cd, Hg, Pb, and Zn concentrations in water collected from the outlet of the wetland. Moreover, diversity and abundance of living organisms, including protozoan, higher plants, terrestrial animals, and birds, increased gradually. The 16-year monitoring results showed a reciprocal relationship, at a certain extent, between restoration of the wetland ecosystem, in other words, the maturity of the wetland, and the long-term efficiency and stability on purifying heavy metal-contaminated wastewater. PMID:16469422

  16. Long-term efficiency and stability of wetlands for treating wastewater of a lead/zinc mine and the concurrent ecosystem development.

    PubMed

    Yang, B; Lan, C Y; Yang, C S; Liao, W B; Chang, H; Shu, W S

    2006-10-01

    A constructed wetland system in Guangdong Province, South of China has been used for treating Pb/Zn mine discharge since 1985. The performance in the purification of the mine discharge and the concurrent ecosystem development within the system during the period of 1985-2000 has been studied. The untreated wastewater contained rather high concentrations of cadmium (Cd) (0.05 mg L(-1)), lead (Pb) (11.5 mg L(-1)), and zinc (Zn) (14.5 mg L(-1)), which greatly exceed the upper limits for industrial wastewater discharge in China. The constructed wetland system effectively removed Cd by 94.00%, Pb by 99.04%, Zn by 97.30%, and total suspended solids (TSS) by 98.95% from the mine discharge over a long period (over 16 years) leading to significant improvement in water quality; it was also found that there were no significantly annual or monthly variations in pH values, As, Cd, Hg, Pb, and Zn concentrations in water collected from the outlet of the wetland. Moreover, diversity and abundance of living organisms, including protozoan, higher plants, terrestrial animals, and birds, increased gradually. The 16-year monitoring results showed a reciprocal relationship, at a certain extent, between restoration of the wetland ecosystem, in other words, the maturity of the wetland, and the long-term efficiency and stability on purifying heavy metal-contaminated wastewater.

  17. Bacteria distribution and dynamics in constructed wetlands based on modelling results.

    PubMed

    Samsó, Roger; García, Joan

    2013-09-01

    Bacteria communities growing in constructed wetlands play a major role on the removal of pollutants from wastewater and the presence of a stable community is a critical factor affecting their performance. With this work we aimed at finding how long it takes for bacterial communities to stabilise in constructed wetlands and at answering specific questions regarding their abundance, spatial distribution and their relative importance on the treatment processes. To this end the numerical model BIO_PORE was used to simulate the dynamics of 6 functional bacteria groups (heterotrophic, autotrophic nitrifying, fermenting, acetotrophic methanogenic, acetotrophic sulphate reducing and sulphide oxidising bacteria) within a wetland for a period of 3 years. Three indicators of bacterial stabilisation were used: 1) total biomass; b) effluent pollutant concentrations and c) Shannon's diversity index. Results indicate that aerobic bacteria dominated the wetland until the 80th day of operation. Anaerobic bacteria dominated the wetland from that moment and until the end of the studied period. Bacteria stability was reached between 400 and 700 days after starting operation. Once the wetland reached stability, sulphate reducing bacteria accounted for the highest biomass of all bacterial groups (46%). The distribution of bacterial communities obtained after bacterial stability is consistent with available experimental results, and was clearly controlled by dissolved oxygen (SO) concentrations and H2S toxicity. After stability, the progressive accumulation of inert solids pushed the location of the active bacteria zone towards the outlet section.

  18. 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. PMID:23291006

  19. 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

  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. Feasibility of constructed wetland planted with Leersia hexandra Swartz for removing Cr, Cu and Ni from electroplating wastewater.

    PubMed

    You, Shao-Hong; Zhang, Xue-Hong; Liu, Jie; Zhu, Yi-Nian; Gu, Chen

    2014-01-01

    As a low-cost treatment technology for effluent, the constructed wetlands can be applied to remove the heavy metals from wastewater. Leersia hexandra Swartz is a metal-accumulating hygrophyte with great potential to remove heavy metal from water. In this study, two pilot-scale constructed wetlands planted with L. hexandra (CWL) were set up in greenhouse to treat electroplating wastewater containing Cr, Cu and Ni. The treatment performance of CWL under different hydraulic loading rates (HLR) and initial metal concentrations were also evaluated. The results showed that CWL significantly reduced the concentrations of Cr, Cu and Ni in wastewater by 84.4%, 97.1% and 94.3%, respectively. High HLR decreased the removal efficiencies of Cr, Cu and Ni; however, the heavy metal concentrations in effluent met Emission Standard of Pollutants for Electroplating in China (ESPE) at HLR less than 0.3 m3/m2 d. For the influent of 5 mg/L Cr, 10 mg/L Cu and 8 mg/L Ni, effluent concentrations were below maximum allowable concentrations in ESPE, indicating that the removal of Cr, Cu and Ni by CWL was feasible at considerably high influent metal concentrations. Mass balance showed that the primary sink for the retention of contaminants within the constructed wetland system was the sediment, which accounted for 59.5%, 83.5%, and 73.9% of the Cr, Cu and Ni, respectively. The data from the pilot wetlands support the view that CWL could be used to successfully remove Cr, Cu and Ni from electroplating wastewater.

  2. Nitrogen detection in the vegetation of prototype constructed wetlands using chlorophyll fluorescence

    NASA Astrophysics Data System (ADS)

    Rosero, Edison; Plazas, Lucero; Solarte, Efraín; Fernández, Adrián; Peña, Enrique; Peña, Miguel

    2009-08-01

    Constructed wetlands are a very efficient, clean and economical way to remove organic contaminants from waste water. In the whole water cleaning process, some other complex processes, such as physical sedimentation, filtration, chemical precipitation, and material absorption by vegetation, are involved. The Nitrogen absorption efficiency by heliconnia psitacorumm, was studied at laboratory scale in a small reactor simulating a subsurface flow constructed wetland. Chlorophyll increasing was measured by fluorescence, using blue LED, 460 [nm] as excitation light source. Besides, spectral differences were observed in the spectral signal and in its derivative, indicating changes in the plant physiological response.

  3. 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.

  4. Enhancing phosphorus removal in constructed wetlands with ochre from mine drainage treatment.

    PubMed

    Heal, K V; Dobbie, K E; Bozika, E; McHaffie, H; Simpson, A E; Smith, K A

    2005-01-01

    No single end-use has yet been identified that is capable of consuming the projected production of ochre (mainly iron (III) oxides) from mine drainage treatment. However, the high sorption capacity of ochre for phosphorus (up to 26 mg kg(-1)) means that it could be used in constructed wetlands to enhance phosphorus removal. Laboratory batch experiments showed that coarse-grained ochre removes 90% of all phosphorus forms from sewage effluent after 15 minutes of shaking. From a larger-scale experiment, it is estimated that constructed wetlands with an ochre substrate should remove phosphorus from sewage effluent for up to 200-300 years. The suitability of ochre for phosphorus removal is being investigated at the field scale in a wastewater constructed wetland (175 m2 area) in Berwickshire, UK. The hydraulic and treatment performance of the wetland were monitored for 15 months prior to installation at the inlet in November 2003 of a tank containing approximately 1200 kg ochre. Results so far show that improved hydraulic design is required for ochre to increase the mean phosphorus removal efficiency of the system (27 +/- 28%), but potentially toxic metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, Zn) have not been released from the ochre into the wetland outflow.

  5. Enhanced long-term nitrogen removal and its quantitative molecular mechanism in tidal flow constructed wetlands.

    PubMed

    Zhi, Wei; Yuan, Li; Ji, Guodong; He, Chunguang

    2015-04-01

    Tidal flow constructed wetlands (TF CWs) have recently been studied as a sustainable technology to achieve enhanced nitrogen removal; however, the underlying mechanisms responsible for removing ammonium (NH4(+)) and nitrate (NO3(-)) have not been compared and quantified at the molecular level (genes) in controlled TF CWs. In this study, two TF CWs T1 (treating NH4(+) wastewater) and T2 (treating NO3(-) wastewater) achieved high removal efficiencies for chemical oxygen demand (COD, 92 ± 2.7% and 95 ± 2.4%, respectively), NH4(+)/NO3(-) (76 ± 3.9% and 97 ± 2.2%, respectively), and total nitrogen (TN, 81 ± 3.5% and 93 ± 2.3%, respectively). Combined analyses revealed that the presence of simultaneous nitrification, anammox, and denitrification processes and the coupling of dissimilatory nitrate reduction to ammonium, ammonia oxidation, and anammox were the primary reason accounted for the robust treatment performance in T1 and T2, respectively. Results from stepwise regression analysis suggested that the NH4(+) removal rate in T1 was collectively controlled by amoA, nxrA, and anammox, while the NO3(-) removal rate in T2 was governed by nxrA and narG gene. PMID:25781063

  6. Enhanced long-term nitrogen removal and its quantitative molecular mechanism in tidal flow constructed wetlands.

    PubMed

    Zhi, Wei; Yuan, Li; Ji, Guodong; He, Chunguang

    2015-04-01

    Tidal flow constructed wetlands (TF CWs) have recently been studied as a sustainable technology to achieve enhanced nitrogen removal; however, the underlying mechanisms responsible for removing ammonium (NH4(+)) and nitrate (NO3(-)) have not been compared and quantified at the molecular level (genes) in controlled TF CWs. In this study, two TF CWs T1 (treating NH4(+) wastewater) and T2 (treating NO3(-) wastewater) achieved high removal efficiencies for chemical oxygen demand (COD, 92 ± 2.7% and 95 ± 2.4%, respectively), NH4(+)/NO3(-) (76 ± 3.9% and 97 ± 2.2%, respectively), and total nitrogen (TN, 81 ± 3.5% and 93 ± 2.3%, respectively). Combined analyses revealed that the presence of simultaneous nitrification, anammox, and denitrification processes and the coupling of dissimilatory nitrate reduction to ammonium, ammonia oxidation, and anammox were the primary reason accounted for the robust treatment performance in T1 and T2, respectively. Results from stepwise regression analysis suggested that the NH4(+) removal rate in T1 was collectively controlled by amoA, nxrA, and anammox, while the NO3(-) removal rate in T2 was governed by nxrA and narG gene.

  7. Reduction of Contaminants (Physical, Chemical, and Microbial) in Domestic Wastewater through Hybrid Constructed Wetland.

    PubMed

    Sehar, Shama; Aamir, Rabia; Naz, Iffat; Ali, Naeem; Ahmed, Safia

    2013-01-01

    The current research was focused mainly on the designing and construction of efficient laboratory scale hybrid constructed wetland (HCW) for the treatment of domestic wastewater. Parameters like COD, BOD5, PO4, SO4, NO3, NO2, and pathogenic indicator microbes were monitored after hydraulic retention time (HRT) of 4, 8, 12, 16, and 20 days. Treatment efficiency of HCW kept on increasing with the increase in hydraulic retention time. Maximum efficiency of HCW was observed with a 20-day HRT, that is, 97.55, 97.5, 89.35, 80.75, 96.04, 91.52, and 98.6% reduction from the zero time value for COD, BOD5, PO4, SO4, NO3, NO2, and fecal coliforms, respectively. After 20 days' time, the treated water was free of almost all nutrients and microbial pollutants. Hence, increasing hydraulic retention time was found to ameliorate the operational competence of HCW. Thus HCW can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries.

  8. Reduction of Contaminants (Physical, Chemical, and Microbial) in Domestic Wastewater through Hybrid Constructed Wetland

    PubMed Central

    Sehar, Shama; Aamir, Rabia; Naz, Iffat; Ali, Naeem; Ahmed, Safia

    2013-01-01

    The current research was focused mainly on the designing and construction of efficient laboratory scale hybrid constructed wetland (HCW) for the treatment of domestic wastewater. Parameters like COD, BOD5, PO4, SO4, NO3, NO2, and pathogenic indicator microbes were monitored after hydraulic retention time (HRT) of 4, 8, 12, 16, and 20 days. Treatment efficiency of HCW kept on increasing with the increase in hydraulic retention time. Maximum efficiency of HCW was observed with a 20-day HRT, that is, 97.55, 97.5, 89.35, 80.75, 96.04, 91.52, and 98.6% reduction from the zero time value for COD, BOD5, PO4, SO4, NO3, NO2, and fecal coliforms, respectively. After 20 days' time, the treated water was free of almost all nutrients and microbial pollutants. Hence, increasing hydraulic retention time was found to ameliorate the operational competence of HCW. Thus HCW can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries. PMID:23724336

  9. 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.

  10. 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.

  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. PMID:26371988

  12. 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. PMID:26296205

  13. 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

  14. Constructed wetlands dye study to determine flow patterns and residence time

    SciTech Connect

    Cano, M.L.; Dorn, P.B.; Vipond, T.E.; Dunn, A.N.; Hawkins, B.F.

    1995-12-31

    Two pilot-scale wetlands (30 m x 6 m) were constructed for tertiary treatment for refinery effluent to remove divalent cationic metals and chronic toxicity. The wetlands have free water surface flow ({approximately}30 cm depth) and are populated with bulrush. To understand the removal of specific pollutants by the biological system and design full scale systems, it is necessary to determine the flow pattern and residence time for each of the wetland cells. A tracer study using a slug injection technique was conducted with rhodamine WT dye. An engineering approach was used to determine retention times by measuring the dye effluent concentration as a function of time and analyzing this profile. Dispersion indexes for the wetlands were also calculated. In addition, flow patterns were determined by periodically sampling a grid within each of the wetland cells. The dye study results indicated: (1) the actual retention time was less than the theoretical retention time (based on volume and flow rate) and (2) partial plug flow regime with a dispersion index of 3.74 was present. These data will be useful for future modeling of pollutant removal by the wetland cells and for the design of full scale systems.

  15. Impact of riverine wetlands construction and operation on stream channel stability: Conceptual framework for geomorphic assessment

    NASA Astrophysics Data System (ADS)

    Rhoads, Bruce L.; Miller, Michael V.

    1990-11-01

    Wetland conservation is a critical environmental management issue. An emerging approach to this issue involves the construction of wetland environments. Because our understanding of wetlands function is incomplete and such projects must be monitored closely because they may have unanticipated impacts on ecological, hydrological, and geomorphological systems. Assessment of project-related impacts on stream channel stability is an important component of riverine wetlands construction and operation because enhanced erosion or deposition associated with unstable rivers can lead to loss of property, reductions in channel capacity, and degradation of water quality, aquatic habitat, and riparian aesthetics. The water/sediment budget concept provides a scientific framework for evaluating the impact of riverine wetlands construction and operation on stream channel stability. This concept is based on the principle of conservation of mass, i.e., the total amount of water and sediment moving through a specific reach of river must be conserved. Long-term measurements of channel sediment storage and other water/sediment budget components provide the basis for distinguishing between project-related impacts and those resulting from other causes. Changes in channel sediment storage that occur as a result of changes in internal inputs of water or sediment signal a project-related impact, whereas those associated with changes in upstream or tributary inputs denote a change in environmental conditions elsewhere in the watershed. A geomorphic assessment program based on the water/sediment budget concept has been implemented at the site of the Des Plaines River Wetlands Demonstration Projection near Chicago, Illinois, USA. Channel sediment storage changed little during the initial construction phase, suggesting that thus far the project has not affected stream channel stability.

  16. Comparative evaluation of three attached growth systems and a constructed wetland for in situ treatment of raw municipal wastewater.

    PubMed

    Loupasaki, E; Diamadopoulos, E

    2013-01-01

    The necessity to treat municipal wastewaters in situ, with a low cost, yet effective system, led to the research of alternative methods for wastewater treatment. Attached growth systems can be an alternative option. Three attached growth systems with different media substrate, a rockwool cubes unit, a Kaldnes rings unit and a plastic bottle caps unit were studied in comparison with a constructed wetland in order to evaluate their ability to treat raw municipal wastewater. The selection of the three different media was based on their high porosity and surface area, as well as their availability and price. Three different operating periods were carried out with variations in the organic loading rate and the feeding frequency. The units were fed intermittently with short resting periods, less than 32 h, and relative high mean organic loading rates of 70, 50 and 30 g chemical oxygen demand (COD)/(m2d), respectively for each operating period. The constructed wetland and the rockwool cubes unit were the most effective, with mean COD reduction as mass rate (mg/d) 88% and 88%, biological oxygen demand 78% and 76%, dissolved organic carbon 73% and 67%, and total suspended solids 91% and 92%, respectively. Total nitrogen reduction was significantly higher at the constructed wetland with mean reduction as mass rate 51%, 60% and 83% for each period, compared to 41%, 43% and 60%, respectively, of the rockwool cubes unit. This study showed that it is possible to design, build and operate in situ small and decentralized treatment systems by using readily available packing materials and with minimum wastewater pretreatment.

  17. Using sorbent waste materials to enhance treatment of micro-point source effluents by constructed wetlands

    NASA Astrophysics Data System (ADS)

    Green, Verity; Surridge, Ben; Quinton, John; Matthews, Mike

    2014-05-01

    Sorbent materials are widely used in environmental settings as a means of enhancing pollution remediation. A key area of environmental concern is that of water pollution, including the need to treat micro-point sources of wastewater pollution, such as from caravan sites or visitor centres. Constructed wetlands (CWs) represent one means for effective treatment of wastewater from small wastewater producers, in part because they are believed to be economically viable and environmentally sustainable. Constructed wetlands have the potential to remove a range of pollutants found in wastewater, including nitrogen (N), phosphorus (P), biochemical oxygen demand (BOD) and carbon (C), whilst also reducing the total suspended solids (TSS) concentration in effluents. However, there remain particular challenges for P and N removal from wastewater in CWs, as well as the sometimes limited BOD removal within these treatment systems, particularly for micro-point sources of wastewater. It has been hypothesised that the amendment of CWs with sorbent materials can enhance their potential to treat wastewater, particularly through enhancing the removal of N and P. This paper focuses on data from batch and mesocosm studies that were conducted to identify and assess sorbent materials suitable for use within CWs. The aim in using sorbent material was to enhance the combined removal of phosphate (PO4-P) and ammonium (NH4-N). The key selection criteria for the sorbent materials were that they possess effective PO4-P, NH4-N or combined pollutant removal, come from low cost and sustainable sources, have potential for reuse, for example as a fertiliser or soil conditioner, and show limited potential for re-release of adsorbed nutrients. The sorbent materials selected for testing were alum sludge from water treatment works, ochre derived from minewater treatment, biochar derived from various feedstocks, plasterboard and zeolite. The performance of the individual sorbents was assessed through

  18. Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland.

    PubMed

    Nivala, J; Hoos, M B; Cross, C; Wallace, S; Parkin, G

    2007-07-15

    A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.

  19. The effect of low temperatures on ammonia removal in a laboratory-scale constructed wetland

    SciTech Connect

    Lee, M.A.; Stansbury, J.S.; Zhang, T.C.

    1999-05-01

    The effect of low temperatures on ammonia removal in constructed wetlands was studied by running a synthetic wastewater through a model, laboratory-scale gravel-filled constructed wetland (in which no plants were grown). The wetland was operated at temperatures of 5, 11.5, 15, and 23 C in an environmentally controlled chamber. An influent ammonia concentration of 45 mg/L as nitrogen was used to simulate typical domestic wastewater. For temperatures of 5, 11.5, 15, and 23 C, the wetland model achieved ammonia removal and nitrification of 45, 44, 56, and 65%, respectively. Thus, over the 18 C temperature range ammonia-nitrogen removal and nitrification rates varied only 20%. There was a net decrease in nitrogen as water passed through the wetland; this could be the result of cell growth or denitrification. Measurements were taken at the inlet, outlet, and four additional locations along the length of the reactor. Measurements were also taken at three different depths. Along the length of the reactor, nearly all nitrification was achieved in the first half of the reactor, then stopped because of low dissolved oxygen concentrations. Nitrification occurred slightly faster at the top of the reactor than at the bottom.

  20. 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.

  1. 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. PMID:26657250

  2. [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. PMID:20391700

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  4. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. 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)...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  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. Behaviour of pharmaceuticals and personal care products in constructed wetland compartments: Influent, effluent, pore water, substrate and plant roots.

    PubMed

    Hijosa-Valsero, María; Reyes-Contreras, Carolina; Domínguez, Carmen; Bécares, Eloy; Bayona, Josep M

    2016-02-01

    Seven mesocosm-scale constructed wetlands (CWs) with different design configurations, dealing with primary-treated urban wastewater, were assessed for the concentration, distribution and fate of ten pharmaceutical and personal care products (PPCPs) [ibuprofen, ketoprofen, naproxen, diclofenac, salicylic acid, caffeine, carbamazepine, methyl dihydrojasmonate, galaxolide and tonalide] and eight of their transformation products (TPs). Apart from influent and effluent, various CW compartments were analysed, namely, substrate, plant roots and pore water. PPCP content in pore water depended on the specific CW configuration. Macrophytes can take up PPCPs through their roots. Ibuprofen, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide were present on the root surface with a predominance of galaxolide and caffeine in all the planted systems. Naproxen, ibuprofen, salicylic acid, methyl dihydrojasmonate, galaxolide and tonalide were uptaken by the roots. In order to better understand the removal processes, biomass measurement and biodegradability studies through the characterization of internal-external isomeric linear alkylbenzenes present on the gravel bed were performed. Three TPs namely, ibuprofen-amide, 3-ethylbenzophenone and 4-hydroxy-diclofenac were identified for the first time in wetland pore water and effluent water, which suggests de novo formation (they were not present in the influent). Conversely, O-desmethyl-naproxen was degraded through the wetland passage since it was detected in the influent but not in the subsequent treatment stages. Biodegradation pathways are therefore suggested for most of the studied PPCPs in the assessed CWs.

  10. Long-term survival of Escherichia coli in lightweight aggregate filter media of constructed wastewater treatment wetlands.

    PubMed

    Paruch, A M

    2011-01-01

    A laboratory scale experiment on the survival of Escherichia coli in samples of filter media from a horizontal subsurface flow constructed wetland treating domestic wastewater was performed. A concentration of E. coli was examined in samples collected from a wetland filter filled with lightweight aggregates (LWA). All samples testing positive for E. coli contamination were used to examine the effect of storage time on the survival of E. coli at three temperature regimes: cold (4°C), mild (10°C) and warm (22°C). It was found that the mild storage condition favoured the growth and survival of E. coli in the tested LWA media. The growth in samples of the uppermost layer of the media lasted for 5.5 months, during which E. coli reached a maximum concentration of 6.4×10(3) MPN/100 g dry matter in the media. It was also observed that E. coli had a greater capacity to survive for extended periods of time in samples collected from the upper layer of the LWA filter compared to samples taken from the deeper layers. The survival of E. coli in the shallowest samples of the wetland filter was remarkably long and unexpected, lasting for a period of over 14 months. PMID:21278480

  11. Behaviour of pharmaceuticals and personal care products in constructed wetland compartments: Influent, effluent, pore water, substrate and plant roots.

    PubMed

    Hijosa-Valsero, María; Reyes-Contreras, Carolina; Domínguez, Carmen; Bécares, Eloy; Bayona, Josep M

    2016-02-01

    Seven mesocosm-scale constructed wetlands (CWs) with different design configurations, dealing with primary-treated urban wastewater, were assessed for the concentration, distribution and fate of ten pharmaceutical and personal care products (PPCPs) [ibuprofen, ketoprofen, naproxen, diclofenac, salicylic acid, caffeine, carbamazepine, methyl dihydrojasmonate, galaxolide and tonalide] and eight of their transformation products (TPs). Apart from influent and effluent, various CW compartments were analysed, namely, substrate, plant roots and pore water. PPCP content in pore water depended on the specific CW configuration. Macrophytes can take up PPCPs through their roots. Ibuprofen, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide were present on the root surface with a predominance of galaxolide and caffeine in all the planted systems. Naproxen, ibuprofen, salicylic acid, methyl dihydrojasmonate, galaxolide and tonalide were uptaken by the roots. In order to better understand the removal processes, biomass measurement and biodegradability studies through the characterization of internal-external isomeric linear alkylbenzenes present on the gravel bed were performed. Three TPs namely, ibuprofen-amide, 3-ethylbenzophenone and 4-hydroxy-diclofenac were identified for the first time in wetland pore water and effluent water, which suggests de novo formation (they were not present in the influent). Conversely, O-desmethyl-naproxen was degraded through the wetland passage since it was detected in the influent but not in the subsequent treatment stages. Biodegradation pathways are therefore suggested for most of the studied PPCPs in the assessed CWs. PMID:26702554

  12. Removal efficiency of a constructed wetland combined with ultrasound and UV devices for wastewater reuse in agriculture.

    PubMed

    Toscano, Attilio; Hellio, Claire; Marzo, Alessia; Milani, Mirco; Lebret, Karen; Cirelli, Giuseppe L; Langergraber, Günter

    2013-01-01

    This study evaluates the treatment efficiency of a chemical-free water treatment for treating the secondary effluent of a municipal wastewater treatment plant with the aim of reusing the water for agriculture. Urban wastewater was treated by three units run in series: a full-scale horizontal sub-surface flow constructed wetland, a small pond with an ultrasound (US) system and a UV device. The treatment efficiency was evaluated in terms of the Italian wastewater limits for irrigation reuse, water quality improvement (removal percentage) and algae bloom control. The tolerable infection risk, associated with the use of wastewaters for irrigating crops, was also assessed by applying the microbial risk analyses proposed in the WHO guidelines for wastewater reuse. The constructed wetland was efficient in reducing physical-chemical and microbiological concentrations, and its efficiency was very steady over the investigation period. The UV system significantly improved water quality (p<0.05) in terms of pathogen concentration with a further average decrease from 0.35 to 1.23 log units, depending on the microbiological parameter. The US device was able to prevent algae bloom on a free water surface and maintain Chlorophyll-a concentration stable and low 2 months after activation.

  13. Recycled vertical flow constructed wetland (RVFCW)--a novel method of recycling greywater for irrigation in small communities and households.

    PubMed

    Gross, A; Shmueli, O; Ronen, Z; Raveh, E

    2007-01-01

    The use of greywater for irrigation is becoming increasingly common. However, raw greywater is often contaminated and can cause environmental harm and pose health risks. Nevertheless, it is often used without any significant pretreatment, a practice mistakenly considered safe. The aim of this study was to develop an economically sound, low-tech and easily maintainable treatment system that would allow safe and sustainable use of greywater for landscape irrigation in small communities and households. The system is based on a combination of vertical flow constructed wetland with water recycling and trickling filter, and is termed recycled vertical flow constructed wetland (RVFCW). The RVFCW's properties, removal efficiency, hydraulic parameters and feasibility were studied, as well as the environmental effects of the treated greywater, as reflected by soil and plant parameters over time. The RVFCW was efficient at removing virtually all of the suspended solids and biological oxygen demand, and about 80% of the chemical oxygen demand after 8h. Fecal coliforms dropped by three to four orders of magnitude from their initial concentration after 8h, but this was not always enough to meet current regulations for unlimited irrigation. The treated greywater had no significant negative impact on plants or soil during the study period. The feasibility analysis indicated a return over investment after approximately three years. We concluded that the RVFCW is a sustainable and promising treatment system for greywater use that can be run and maintained by unskilled operators.

  14. 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.

  15. 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

  16. 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. PMID:26468606

  17. 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.

  18. Upgrading constructed wetlands phosphorus reduction from a dairy effluent using electric arc furnace steel slag filters.

    PubMed

    Weber, D; Drizo, A; Twohig, E; Bird, S; Ross, D

    2007-01-01

    In 2003, a subsurface flow constructed wetlands (SSF-CW) system was built at the University of Vermont (UVM) Paul Miller Dairy Farm as an alternative nutrient management approach for treating barnyard runoff and milk parlour waste. Given the increasing problem of phosphorus (P) pollution in the Lake Champlain region, a slag based P-removal filter technology (PFT) was established (2004) at the CW with two objectives: (i) to test the filters' efficiency as an upgrade unit for improving P removal performance via SSF-CW (ii) to investigate the capacity of filters technology to remove P as a "stand alone" unit. Six individual filters (F1-F6) were filled with electric arc furnace (EAF) steel slag, each containing 112.5 kg of material with a pore volume of 21 L. F1-F4, fed with CW treated water, received approximately 2.17 g DRP kg(-1) EAF steel slag (0.25 kg DRP total) during the 259 day feeding period. F1-F4 retained 1.7 g DRP kg(-1) EAF steel slag, resulting in an average P removal efficiency of 75%. The addition of filters improved CW DRP removal efficiency by 74%. F5 and F6, fed non-treated water, received 1.9 g DRP kg(-1) EAF steel slag (0.22 kg DRP in total) and retained 1.5 g DRP kg(-1) resulting in a P removal efficiency of 72%. The establishment of the EAF slag based PFT is the first in-field evaluation of this technology to reduce P from dairy farm effluent in Vermont.

  19. Temperature, plants, and oxygen: how does season affect constructed wetland performance?

    PubMed

    Stein, Otto R; Hook, Paul B

    2005-01-01

    The influence of temperature and plant-mediated oxygen transfer continues to draw attention from researchers, practitioners and regulators interested in the use of constructed wetlands for wastewater treatment. Because the vast majority of research on constructed wetland performance has been conducted during periods of active plant growth, the true influence of temperature, season, and plant species selection on constructed wetlands performance has not yet been evaluated adequately. In this article, we briefly summarize changes in the understanding of these influences on wetland performance, and suggest that effects of temperature and oxygen transfer are not readily separable because both factors respond to seasonal cycles and because effects of one can offset the other. We further speculate that the net effect of seasonal variation in these factors is such that plant-mediated oxygen transfer affects water treatment most in winter. Results of controlled-environment experiments conducted at Montana State University support these perspectives. Different plant species' capacities to oxidize the root zone responded differently to seasonal cycles of growth and dormancy, and species' effects on wastewater treatment were most pronounced in winter.

  20. 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.

  1. Effect of feeding strategies on pharmaceutical removal by subsurface flow constructed wetlands.

    PubMed

    Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Nguyen, Anh Tuan; Law, Wing-Keung; Ng, Wun Jern; Tan, Soon Keat

    2012-01-01

    This study presents findings on an assessment of the effect of continuous and batch feeding strategies on the removal of selected pharmaceuticals from synthetic wastewater. Six mesocosm-scale constructed wetlands, including three horizontal subsurface flow constructed wetlands and three sand filters, were set up at the campus of Nanyang Technological University, Singapore. The findings showed that ibuprofen and diclofenac removal in the wetlands was significantly ( < 0.05) enhanced in the batch versus continuous mode. In contrast, naproxen and carbamazepine showed no significant differences ( > 0.05) in elimination under either feeding strategy. Our results also clearly showed that the presence of plants exerts a stimulatory effect on pharmaceutical removal for ibuprofen, diclofenac, and naproxen in batch and continuous mode. Estimation of the quantitative role of this stimulatory effect on pharmaceutical elimination of batch operation as compared with the effect of the presence of the higher plant alone showed that batch operation may account for 40 to 87% of the contribution conferred by the aquatic plant. The findings of this study imply that where maximal removal of pharmaceutical compounds is desired, periodic draining and filling might be the preferred operational strategy for full-scale, subsurface flow constructed wetlands.

  2. Temperature, plants, and oxygen: how does season affect constructed wetland performance?

    PubMed

    Stein, Otto R; Hook, Paul B

    2005-01-01

    The influence of temperature and plant-mediated oxygen transfer continues to draw attention from researchers, practitioners and regulators interested in the use of constructed wetlands for wastewater treatment. Because the vast majority of research on constructed wetland performance has been conducted during periods of active plant growth, the true influence of temperature, season, and plant species selection on constructed wetlands performance has not yet been evaluated adequately. In this article, we briefly summarize changes in the understanding of these influences on wetland performance, and suggest that effects of temperature and oxygen transfer are not readily separable because both factors respond to seasonal cycles and because effects of one can offset the other. We further speculate that the net effect of seasonal variation in these factors is such that plant-mediated oxygen transfer affects water treatment most in winter. Results of controlled-environment experiments conducted at Montana State University support these perspectives. Different plant species' capacities to oxidize the root zone responded differently to seasonal cycles of growth and dormancy, and species' effects on wastewater treatment were most pronounced in winter. PMID:15921285

  3. 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. PMID:25461411

  4. 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.

  5. Key design factors affecting microbial community composition and pathogenic organism removal in horizontal subsurface flow constructed wetlands.

    PubMed

    Morató, Jordi; Codony, Francesc; Sánchez, Olga; Pérez, Leonardo Martín; García, Joan; Mas, Jordi

    2014-05-15

    Constructed wetlands constitute an interesting option for wastewater reuse since high concentrations of contaminants and pathogenic microorganisms can be removed with these natural treatment systems. In this work, the role of key design factors which could affect microbial removal and wetland performance, such as granular media, water depth and season effect was evaluated in a pilot system consisting of eight parallel horizontal subsurface flow (HSSF) constructed wetlands treating urban wastewater from Les Franqueses del Vallès (Barcelona, Spain). Gravel biofilm as well as influent and effluent water samples of these systems were taken in order to detect the presence of bacterial indicators such as total coliforms (TC), Escherichia coli, fecal enterococci (FE), Clostridium perfringens, and other microbial groups such as Pseudomonas and Aeromonas. The overall microbial inactivation ratio ranged between 1.4 and 2.9 log-units for heterotrophic plate counts (HPC), from 1.2 to 2.2 log units for total coliforms (TC) and from 1.4 to 2.3 log units for E. coli. The presence of fine granulometry strongly influenced the removal of all the bacterial groups analyzed. This effect was significant for TC (p=0.009), E. coli (p=0.004), and FE (p=0.012). Shallow HSSF constructed wetlands were more effective for removing Clostridium spores (p=0.039), and were also more efficient for removing TC (p=0.011) and E. coli (p=0.013) when fine granulometry was used. On the other hand, changes in the total bacterial community from gravel biofilm were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of polymerase chain reaction (PCR)-amplified fragments of the 16S rRNA gene recovered from DGGE bands. Cluster analysis of the DGGE banding pattern from the different wetlands showed that microbial assemblages separated according to water depth, and sequences of different phylogenetic groups, such as Alpha, Beta and Delta-Proteobacteria, Nitrospirae, Bacteroidetes

  6. Comparative study of microbial community structure in integrated vertical-flow constructed wetlands for treatment of domestic and nitrified wastewaters.

    PubMed

    Chang, Jun-Jun; Wu, Su-Qing; Liang, Kang; Wu, Zhenbin; Liang, Wei

    2015-03-01

    Microbial processes play a vital important role in the removal of contaminants in constructed wetland (CW). However, the microbial physiology and community structure can be influenced by environmental conditions. In this study, four pilot-scale integrated vertical-flow constructed wetlands (IVCWs) were employed to treat domestic and nitrified wastewaters. The microbial properties, along with their response to wastewater quality characteristics and seasonal variation, were determined. The results showed higher Shannon-Weiner diversity (H) and evenness (E) index of fatty acids (FAs), and relative abundances of signature FAs in down-flow cells and in the systems fed with domestic wastewater (DW). The relative abundances of fungi and gram-negative and aerobic bacteria were greater in up-flow cells. The dominant anaerobic bacteria found in most cells might be accounted for the prevailing anaerobic environment within the wetland beds, which could mean that the system fed with nitrified wastewater (NW) should perform better in nitrogen removal. The redundancy analysis (RDA) showed that pollutant concentrations, especially organic matter, influence the FA compositions greatly, and the most significant difference of microbial community structures was detected in down-flow cells fed with DW and up-flow ones with NW. The branched FAs, which could be used to represent anaerobic bacteria, were observed in down-flow cells treating DW and had a significant positive correlation with chemical oxygen demand (COD) concentration, probably suggesting the important role of anaerobic bacteria in organic matter degradation in the IVCWs. Seasonal variation, however, did not greatly influence the microbial community structure in the IVCWs.

  7. Dynamics of nitrobenzene degradation and interactions with nitrogen transformations in laboratory-scale constructed wetlands.

    PubMed

    Lv, Tao; Wu, Shubiao; Hong, Hao; Chen, Li; Dong, Renjie

    2013-04-01

    Three laboratory-scale CWs (i.e., tidal flow CW as well as planted and unplanted horizontal subsurface flow CWs) were set up to treat artificial nitrobenzene (NB) industry effluents in this study. An inflow NB load equal to or less than 70 mg/L achieved approximately 95% NB removal regardless of wetland type. When NB influent load increased to 160 mg/L, NB removal efficiency decreased to 57%, 46%, and 33% in planted and unplanted horizontal CWs as well as tidal flow CWs, respectively. Higher NB degradation efficiency in planted horizontal CW highlighted the positive effect of wetland plants. Moreover, strong inhibition of nitrogen removal was initiated in CWs with an increase of NB loads to 160 mg/L, which was probably caused by NB toxicity. The investigation indicated not only the potential application of treatment wetlands as a secondary ecological treatment system for NB-containing wastewater, but also the interactions with nitrogen transformations in CWs.

  8. Leachate treatment system using constructed wetlands, Town of Fenton sanitary landfill, Broome County, New York. Final report

    SciTech Connect

    Not Available

    1993-11-01

    Municipal sanitary landfills generate leachate that New York State regulations require to be collected and treated to avoid contaminating surface water and groundwater. One option for treating leachate is to haul it to municipal wastewater treatment facility. This option may be expensive, may require excessive energy for transportation, and may require pretreatment to protect the receiving facility`s processes. An alternative is on-site treatment and discharge. Personnel from the Town of Fenton, New York; Hawk Engineering, P.C.; Cornell University; and Ithaca College designed, built, and operated a pilot constructed wetland for treating leachate at the Town of Fenton`s municipal landfill. The system, consisting of two overland flow beds and two subsurface flow beds has been effective for 18 months in reducing levels of ammonia (averaging 85% removal by volatilization and denitrification) and total iron (averaging 95% removal by precipitation and sedimentation), two key constituents of the Fenton landfill`s leachate. The system effects these reductions with zero chemical and energy inputs and minimal maintenance. A third key constituent of the leachate, manganese, apparently passes through the beds with minimal removal. Details and wetland considerations are described.

  9. EPS solubilization treatment by applying the biosurfactant rhamnolipid to reduce clogging in constructed wetlands.

    PubMed

    Du, Mingpu; Xu, Dong; Trinh, Xuantung; Liu, Shuangyuan; Wang, Mei; Zhang, Yi; Wu, Junmei; Zhou, Qiaohong; Wu, Zhenbin

    2016-10-01

    Application of extracellular polymeric substances (EPS) solubilization treatment with biosurfactant rhamnolipid (RL) to reduce clogging in constructed wetlands was first conducted in this study. The results showed significant improvement in the solubilization and dispersion of clogging matter following the treatment. And RL dosage of 0.09-0.15g/L altered microbial group make-up and had an overall positive effect on the growth of microorganisms. Moreover, RL was found to enhance EPS dissolution and dispersion, which was beneficial for the release of enzymes embedded in the EPS, and resulted in enhanced pollutant removal. The treatment had no apparent detrimental effect on wetland plants. Our results indicate that the optimum dosage of RL is 0.12g/L, and that the approach provides a promising and moderate option to reverse wetland clogging through RL-mediated solubilization treatment. PMID:27428300

  10. EPS solubilization treatment by applying the biosurfactant rhamnolipid to reduce clogging in constructed wetlands.

    PubMed

    Du, Mingpu; Xu, Dong; Trinh, Xuantung; Liu, Shuangyuan; Wang, Mei; Zhang, Yi; Wu, Junmei; Zhou, Qiaohong; Wu, Zhenbin

    2016-10-01

    Application of extracellular polymeric substances (EPS) solubilization treatment with biosurfactant rhamnolipid (RL) to reduce clogging in constructed wetlands was first conducted in this study. The results showed significant improvement in the solubilization and dispersion of clogging matter following the treatment. And RL dosage of 0.09-0.15g/L altered microbial group make-up and had an overall positive effect on the growth of microorganisms. Moreover, RL was found to enhance EPS dissolution and dispersion, which was beneficial for the release of enzymes embedded in the EPS, and resulted in enhanced pollutant removal. The treatment had no apparent detrimental effect on wetland plants. Our results indicate that the optimum dosage of RL is 0.12g/L, and that the approach provides a promising and moderate option to reverse wetland clogging through RL-mediated solubilization treatment.

  11. Treatment of gully pot liquor containing heavy metals with constructed wetlands in Scotland.

    PubMed

    Scholz, M; Anderson, P; Forman, B I

    2005-01-01

    The aim of this investigation was to assess the treatment efficiencies for gully pot liquor of 12 experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) and filter media of different adsorption capacities in a cold climate. Seven of the twelve filters received inflow water spiked with heavy metals. For one year, hydrated copper nitrate and hydrated nickel nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm water runoff. The inflow concentrations for dissolved copper, nickel and nitrate-nitrogen were approximately 1.0, 1.0 and 1.45 mg/l, respectively, which represent mean loading rates of 0.063 g/m2/d for Filters 2 and 7 to 11, and 0.115 g/m2/d for Filter 12. For these filters receiving metals, an obvious breakthrough of dissolved nickel was recorded after road gritting and salting during winter. Sodium chloride was responsible for nickel leaching. Reductions of copper, nickel, biochemical oxygen demand and suspended solids were frequently insufficient compared to international secondary wastewater treatment standards. Moreover, the overall filtration performance for all filters was similar.

  12. French vertical-flow constructed wetlands in mountain areas: how do cold temperatures impact performances?

    PubMed

    Prost-Boucle, S; Garcia, O; Molle, P

    2015-01-01

    The French version of vertical-flow constructed wetlands (VFCWs) is characterized by treating directly raw wastewater on a first-stage filter. VFCW is a well developed technology with more than 3,500 plants in operation in France. However, VFCW performance may be affected under the low temperatures reached in mountain areas during winter. The effect of cold conditions over 12 plants, ranging from 75 to 1,900 person equivalent and from 680 to 1,500 m above sea level, was studied over 2 years. The plant hydraulic loads, and air and filter temperatures were continuously measured. In addition, 24-h flow proportional sampling, at each stage of treatment, was conducted in summer (as a reference) and winter. Online measurements of ammonium and nitrates were also analyzed to describe the nitrogen removal dynamics. Since no impact on chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids removal was observed, the effect of cold temperatures on nitrification was further analyzed. Nitrogen removal was relatively unaffected during winter season. Significant effects were confirmed only for the second stage for loads above 10 gTKN/m²/d (TKN: total Kjeldahl nitrogen). Temperature profiles allowed analysis of the filter buffer capacity in terms of freezing. Under minimal air temperature of -19 °C, no critical operation was observed, although design and operation recommendations can be provided to ensure suitable plant performances.

  13. Nitrogen and COD removal from domestic and synthetic wastewater in subsurface-flow constructed wetlands.

    PubMed

    Collison, R S; Grismer, M E

    2013-09-01

    Comparisons of the performance of constructed-wetland systems (CWs) for treating domestic wastewater in the laboratory and field may use pathogen-free synthetic wastewater to avoid regulatory health concerns. However, little to no data are available describing the relative treatment efficiencies of CWs to both actual and synthetic domestic wastewaters so as to enable such comparison. To fill this gap, treatment performances with respect to organics (chemical organic demand; COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) and a similar-strength synthetic wastewater under planted and non-planted subsurface-flow CWs are determined. One pair of CWs was planted with cattails in May 2008, whereas the adjacent system was non-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each CWs, and effluent samples were collected and tested for COD and nitrogen species regularly during four different periods over six months. Overall, statistically significant greater removal of COD (-12%) and nitrogen (-5%) occurred from the synthetic as compared with the domestic wastewater from the planted and non-planted CWs. Effluent BOD5/COD ratios from the synthetic wastewater CWs averaged nearly twice that from the domestic wastewater CWs (0.17 vs 0.10), reflecting greater concentrations of readily degraded compounds. That removal fractions were consistent across the mid-range loading rates to the CWs suggests that the synthetic wastewater can be used in testing laboratory CWs with reasonable success in application of their results to the field.

  14. Influence of surface layer on hydrology and biology of gravel bed vertical flow constructed wetlands.

    PubMed

    Chazarenc, F; Merlin, G

    2005-01-01

    In France, gravel vertical flow constructed wetlands (gVFCWs) were adapted to treat raw wastewater, which led to important accumulations of matter in filters (organic and mineral). To prevent clogging, large gravel sizes were employed (O 2-6 mm). The aim of this paper was to present the influences of matter accumulation on the hydraulic and biological behaviour of the system. A one-year survey of accumulated matter content and potential respiration activities was completed in three gVFCWs (operating for 3, 4 and 8 years). Cores were sampled into filters. Results showed a vertical stratification of accumulated matter and respiration rates. Dry accumulated matter quantities ranged from 20 kg m(-2) (3 and 4 years operating) to 80 kg m(-2) in the oldest plant (8 years). Potential respiration was larger in the oldest plant (75g O2m(-2)h(-1)) than in the most recent one (15g O2m(-2)h(-1)). Accumulated matter seemed to play a role both on the water retention (enhancing initial percolation time by 5 times) and biological profile (enhancing microfauna's diversity). Contrary to what is generally proposed in the literature, accumulated matter in French gVFCWs seemed to provide better treatment efficiency without leading to surface clogging compared to systems using sand.

  15. Nitrogen isotope fractionation as a tool for determining denitrification in constructed wetlands.

    PubMed

    Søvik, A K; Mørkved, P T

    2007-01-01

    Constructed wetlands (CWs) treat municipal wastewater through the retention of nutrients and particles. The retention of nitrogen (N) was studied in the laboratory using columns and meso-scale trenches filled with shellsand and light-weight aggregates (LWA). The objective was to examine whether measuring the natural abundance of delta15N in NO3(-) could be used to estimate the relative contribution of denitrification to the total NO3(-) removal in these treatment systems. In both the columns and the trenches it was seen that denitrification was more efficient in shellsand and LWA collected from on-site treatment systems compared to new LWA. This was due to the high pH value (about 10) of new LWA. The enrichment factors (epsilon) from the column study were in general lower than values found in laboratory tests of isotope discrimination in denitrification, but similar to epsilon values found for denitrification in groundwater systems. No enrichment factors could be found for the trench study due to simultaneous denitrification and nitrification and inhomogeneous N transformation patterns. When NH4+ was partially nitrified in the upper parts of the trench, this diluted the 15N enrichment of NO3(-) due to denitrification. Thus, in systems with high NH4+ concentrations and partial aerobic conditions, the method of natural abundance is not suitable for estimating the relative contribution of denitrification to the total NO3(-) removal. PMID:17802852

  16. Intermittent aeration to improve wastewater treatment efficiency in pilot-scale constructed wetland.

    PubMed

    Uggetti, Enrica; Hughes-Riley, Theodore; Morris, Robert H; Newton, Michael I; Trabi, Christophe L; Hawes, Patrick; Puigagut, Jaume; García, Joan

    2016-07-15

    Forced aeration of horizontal subsurface flow constructed wetlands (HSSF CWs) is nowadays a recognized method to improve treatment efficiency, mainly in terms of ammonium removal. While numerous investigations have been reported testing constant aeration, scarce information can be found about the efficiency of intermittent aeration. This study aims at comparing continuous and intermittent aeration, establishing if there is an optimal regime that will increase treatment efficiency of HSSF CWs whilst minimizing the energy requirement. Full and intermittent aeration were tested in a pilot plant of three HSSF CWs (2.64m(2) each) fed with primary treated wastewater. One unit was fully aerated; one intermittently aerated (i.e. by setting a limit of 0.5mg/L dissolved oxygen within the bed) with the remaining unit not aerated as a control. Results indicated that intermittent aeration was the most successful operating method. Indeed, the coexistence of aerobic and anoxic conditions promoted by the intermittent aeration resulted in the highest COD (66%), ammonium (99%) and total nitrogen (79%) removals. On the other hand, continuous aeration promotes ammonium removal (99%), but resulted in nitrate concentrations in the effluent of up to 27mg/L. This study demonstrates the high potential of the intermittent aeration to increase wastewater treatment efficiency of CWs providing an extreme benefit in terms of the energy consumption.

  17. [Effect of Intermittent Aeration on Nitrogen Removal Efficiency in Vertical Subsurface Flow Constructed Wetland].

    PubMed

    Wang, Jian; Li, Huai-zheng; Zhen, Bao-chong; Liu, Zhen-dong

    2016-03-15

    One-stage vertical subsurface flow constructed wetlands (CWs) were used to treat effluent from grit chamber in municipal wastewater treatment plant. The CW was divided into aerobic zone and anoxic zone by means of raising the effluent level and installing a perforated pipe. Two parameters (the ratio of aeration time and nonaeration time, aeration cycle) were optimized in the experiment to enhance nitrogen removal efficiency. The results suggested that the removal rates of COD and NH₄⁺-N increased while TN showed a trend of first increasing and then decreasing with the increasing ratio. When the ratio was 3:1, the C/N value in the anoxic zone was 4. 8. And the TN effluent concentration was 15.8 mg · L⁻¹ with the highest removal rate (62.1%), which was increased by 12.7% compared with continuous aeration. As the extension of the aeration cycle, the DO effluent concentration as well as the removal rates of COD and NH: -N declined gradually. The TN removal rate reached the maximum (65.5%) when the aeration cycle was 6h. However, the TN removal rate dropped rapidly when the cycle exceeded the hydraulic retention time in the anoxic zone.

  18. Effect of influent aeration on removal of organic matter from coffee processing wastewater in constructed wetlands.

    PubMed

    Rossmann, Maike; Matos, Antonio Teixeira; Abreu, Edgar Carneiro; Silva, Fabyano Fonseca; Borges, Alisson Carraro

    2013-10-15

    The aim of the present study was to evaluate the influence of aeration and vegetation on the removal of organic matter in coffee processing wastewater (CPW) treated in 4 constructed wetlands (CWs), characterized as follows: (i) ryegrass (Lolium multiflorum) cultivated system operating with an aerated influent; (ii) non-cultivated system operating with an aerated influent, (iii) ryegrass cultivated system operating with a non-aerated influent; and (iv) non-cultivated system operating with a non-aerated influent. The lowest average chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of 87, 84 and 73%, respectively, were obtained in the ryegrass cultivated system operating with a non-aerated influent. However, ryegrass cultivation did not influence the removal efficiency of organic matter. Artificial aeration of the CPW, prior to its injection in the CW, did not improve the removal efficiencies of organic matter. On other hand it did contribute to increase the instantaneous rate at which the maximum COD removal efficiency was reached. Although aeration did not result in greater organic matter removal efficiencies, it is important to consider the benefits of aeration on the removal of the other compounds.

  19. French vertical-flow constructed wetlands in mountain areas: how do cold temperatures impact performances?

    PubMed

    Prost-Boucle, S; Garcia, O; Molle, P

    2015-01-01

    The French version of vertical-flow constructed wetlands (VFCWs) is characterized by treating directly raw wastewater on a first-stage filter. VFCW is a well developed technology with more than 3,500 plants in operation in France. However, VFCW performance may be affected under the low temperatures reached in mountain areas during winter. The effect of cold conditions over 12 plants, ranging from 75 to 1,900 person equivalent and from 680 to 1,500 m above sea level, was studied over 2 years. The plant hydraulic loads, and air and filter temperatures were continuously measured. In addition, 24-h flow proportional sampling, at each stage of treatment, was conducted in summer (as a reference) and winter. Online measurements of ammonium and nitrates were also analyzed to describe the nitrogen removal dynamics. Since no impact on chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids removal was observed, the effect of cold temperatures on nitrification was further analyzed. Nitrogen removal was relatively unaffected during winter season. Significant effects were confirmed only for the second stage for loads above 10 gTKN/m²/d (TKN: total Kjeldahl nitrogen). Temperature profiles allowed analysis of the filter buffer capacity in terms of freezing. Under minimal air temperature of -19 °C, no critical operation was observed, although design and operation recommendations can be provided to ensure suitable plant performances. PMID:25909733

  20. Phytoremediation of Landfill Leachate with Colocasia esculenta, Gynerum sagittatum and Heliconia psittacorum in Constructed Wetlands.

    PubMed

    Madera-Parra, C A; Peña-Salamanca, E J; Peña, M R; Rousseau, D P L; Lens, P N L

    2015-01-01

    This study assessed the accumulation of Cd (II), Hg (II), Cr (VI) and Pb (II) in Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) planted in constructed wetlands treating synthetic landfill leachate. Sixteen bioreactors were operated in two experimental blocks. Metal concentrations in the influent and effluent; root, stem, branch and leaves of plants were analysed, as well as COD, N-NH4+, TKN, T, pH, ORP, DO, and EC. Average removal efficiencies of COD, TKN and NH4+-N were 66, 67 and 72%, respectively and heavy metal removal ranged from 92 to 98% in all units. Cr (VI) was not detected in any effluent sample. The bioconcentration factors (BCF) were 10(0) -10(2). The BCF of Cr (VI) was the lowest: 0.59 and 2.5 (L kg(-1)) for Gs and He respectively; whilst Cd (II) had the highest (130-135 L kg(-1)) for Gs. Roots showed a higher metal content than shoots. Translocation factors (TF) were lower, He was the plant exhibiting TFs>1 for Pb (II), Cr (T) and Hg (II) and 0.4-0.9 for Cd (II) and Cr (VI). The evaluated plants demonstrate their suitability for phytoremediation of landfill leachate and all of them can be categorized as metals accumulators.

  1. Small scale recirculating vertical flow constructed wetland (RVFCW) for the treatment and reuse of wastewater.

    PubMed

    Gross, A; Sklarz, M Y; Yakirevich, A; Soares, M I M

    2008-01-01

    The quantity of freshwater available worldwide is declining, revealing a pressing need for its more efficient use. Moreover, in many developing countries and lightly populated areas, raw wastewater is discarded into the environment posing serious ecological and health problems. Unfortunately, this situation will persist unless low-cost, effective and simple technologies are brought in. The aim of this study is to present such a treatment method, a novel setup which is termed recirculating vertical flow constructed wetland (RVFCW). The RVFCW is composed of two components: (i) a three-layer bed consisting of planted organic soil over an upper layer of filtering media (i.e. tuff or beads) and a lower layer of limestone pebbles, and (ii) a reservoir located beneath the bed. Wastewater flows directly into the plant root zone and trickles down through the three-layer bed into the reservoir, allowing passive aeration. From the reservoir the water is recirculated back to the bed, several times, until the desired purification is achieved. The results obtained show that the RVFCW is an effective and convenient strategy to treat (domestic, grey and agro) wastewater for re-use in irrigation. The system performance is expected to be further improved once current optimization experiments and mathematical modeling studies are concluded.

  2. Nitrogen and COD removal from domestic and synthetic wastewater in subsurface-flow constructed wetlands.

    PubMed

    Collison, R S; Grismer, M E

    2013-09-01

    Comparisons of the performance of constructed-wetland systems (CWs) for treating domestic wastewater in the laboratory and field may use pathogen-free synthetic wastewater to avoid regulatory health concerns. However, little to no data are available describing the relative treatment efficiencies of CWs to both actual and synthetic domestic wastewaters so as to enable such comparison. To fill this gap, treatment performances with respect to organics (chemical organic demand; COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) and a similar-strength synthetic wastewater under planted and non-planted subsurface-flow CWs are determined. One pair of CWs was planted with cattails in May 2008, whereas the adjacent system was non-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each CWs, and effluent samples were collected and tested for COD and nitrogen species regularly during four different periods over six months. Overall, statistically significant greater removal of COD (-12%) and nitrogen (-5%) occurred from the synthetic as compared with the domestic wastewater from the planted and non-planted CWs. Effluent BOD5/COD ratios from the synthetic wastewater CWs averaged nearly twice that from the domestic wastewater CWs (0.17 vs 0.10), reflecting greater concentrations of readily degraded compounds. That removal fractions were consistent across the mid-range loading rates to the CWs suggests that the synthetic wastewater can be used in testing laboratory CWs with reasonable success in application of their results to the field. PMID:24175415

  3. Treatment of municipal wastewater using horizontal flow constructed wetlands in Egypt.

    PubMed

    Abou-Elela, Sohair I; Golinelli, G; Saad El-Tabl, Abdou; Hellal, Mohammed S

    2014-01-01

    The aim of this study was to evaluate the performance of two pilot horizontal flow constructed wetlands (HFCWs) with and without vegetation. Three types of plants namely Canna, Phragmites australis and Cyprus papyrus were used. The surface area of each plant was 654 m(2). The flow rate was 20 m(3) d(-1) and the organic loading rate range was 1.7-3.4 kg BOD d(-1) with a detention time of 11 days. The results obtained showed that planted HFCW produced high quality effluent in terms of reduction of chemical oxygen demand (COD; 88%), biochemical oxygen demand (BOD; 91%) and total suspended solids (TSS; 92%) as well as nutrient removal. In addition, 4 logs of total coliform were removed from the planted unit compared with only 3 logs in the unplanted one. The phosphate uptake by the plants reached 29, 30.91 and 38.9 g P m(-2) for Canna, Phragmites and Cyprus, respectively, with 60% removal rate in the treated effluent. The nitrogen uptake by the same plants reached 63.1, 49.46 and 82.33 g N m(-2). Although, the unplanted unit proved to be efficient in the removal of COD, BOD and TSS, it lacks efficiency in pathogen and nutrient removal. The reclaimed wastewater, after disinfection, could be reused for non-restricted irrigation purposes. PMID:24434966

  4. Fate of mixed pesticides in an integrated recirculating constructed wetland (IRCW).

    PubMed

    Tang, Xiaoyan; Yang, Yang; Tao, Ran; Chen, Peijun; Dai, Yunv; Jin, Congcong; Feng, Xu

    2016-11-15

    In this study, three model integrated recirculating constructed wetlands (IRCWs) planted with and without Cyperus alternifolius were used to investigate their ability to remove four pesticides (chlorpyrifos, endosulfan, fenvalerate, diuron). Iron (Fe)-impregnated biochar produced by Cyperus alternifolius was added as a primary substrate. Results showed that all four pesticides were efficiently removed in the three IRCWs. The highest pesticide removals were achieved when Fe-impregnated biochar was added to the IRCW (99%), followed by the planted (64-99%) and plant-free IRCW (45-99%). The removal of pesticides in IRCWs followed first-order kinetics, with half-lives of 1.5-11.6h. A mass balance study revealed that sorption (32.2-98.6%) and microbial degradation (1.3-52.8%) were the main removal processes in all IRCWs. This study suggests that the IRCW is a promising system to treat pesticide-contaminated water, and plant and Fe-impregnated biochar can enhance pesticide removal. PMID:27496077

  5. Sulfate removal and sulfur transformation in constructed wetlands: The roles of filling material and plant biomass.

    PubMed

    Chen, Yi; Wen, Yue; Zhou, Qi; Huang, Jingang; Vymazal, Jan; Kuschk, Peter

    2016-10-01

    Sulfate in effluent is a challenging issue for wastewater reuse around the world. In this study, sulfur (S) removal and transformation in five batch constructed wetlands (CWs) treating secondary effluent were investigated. The results showed that the presence of the plant cattail (Typha latifolia) had little effect on sulfate removal, while the carbon-rich litter it generated greatly improved sulfate removal, but with limited sulfide accumulation in the pore-water. After sulfate removal, most of the S was deposited with the valence states S (-II) and S (0) on the iron-rich gravel surface, and acid volatile sulfide was the main S sink in the litter-added CWs. High-throughput pyrosequencing revealed that sulfate-reducing bacteria (i.e. Desulfobacter) and sulfide-oxidizing bacteria (i.e. Thiobacillus) were dominant in the litter-added CWs, which led to a sustainable S cycle between sulfate and sulfide. Overall, this study suggests that recycling plant litter and iron-rich filling material in CWs gives an opportunity to utilize the S in the wastewater as both an electron acceptor for sulfate reduction and as an electron donor for nitrate reduction coupled with sulfide oxidation. This leads to the simultaneous removal of sulfate, nitrate, and organics without discharging toxic sulfide into the receiving water body. PMID:27423407

  6. Management of arsenic-accumulated waste from constructed wetland treatment of mountain tap-water.

    PubMed

    Nakwanit, Sannop; Visoottiviseth, Pornsawan; Khokiattiwong, Somkiat; Sangchoom, Wantana

    2011-01-30

    Arsenic-contaminated mountain tap water supply in Ron Phibun District, Nakorn Si Thammarat Province, Thailand poses a health hazard. Arsenic was removed using a constructed wetland (CW) system, in which the treated contaminated tap water was sedimented in 3 consecutive ponds before entering into the CW ponds, containing either Cyperus spp. or Colocasia esculenta. Following 1 year of operation both plants had similar ability to remove arsenic from mountain tap water. Arsenic was mostly concentrated at the roots of both plants. Arsenic in C. esculenta leaves was allowed to leach out in freshwater for 149 days, but the level (0.05 mg L(-1)) was much lower than standard guidelines for industrial discharge. For Cyperus spp., young shoots were utilized as ornamental plants. As the sediments contained high arsenic levels, they were converted by a solidification/stabilization (S/S) system into cement-containing blocks, which after curing for 21 days produced arsenic leaching at levels that did not require a secure landfill for storage. The success of this study demonstrated that CW combined with appropriate S/S system is a suitable approach for Thailand in removing arsenic from contaminated water. PMID:21036470

  7. Phytoremediation of Landfill Leachate with Colocasia esculenta, Gynerum sagittatum and Heliconia psittacorum in Constructed Wetlands.

    PubMed

    Madera-Parra, C A; Peña-Salamanca, E J; Peña, M R; Rousseau, D P L; Lens, P N L

    2015-01-01

    This study assessed the accumulation of Cd (II), Hg (II), Cr (VI) and Pb (II) in Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) planted in constructed wetlands treating synthetic landfill leachate. Sixteen bioreactors were operated in two experimental blocks. Metal concentrations in the influent and effluent; root, stem, branch and leaves of plants were analysed, as well as COD, N-NH4+, TKN, T, pH, ORP, DO, and EC. Average removal efficiencies of COD, TKN and NH4+-N were 66, 67 and 72%, respectively and heavy metal removal ranged from 92 to 98% in all units. Cr (VI) was not detected in any effluent sample. The bioconcentration factors (BCF) were 10(0) -10(2). The BCF of Cr (VI) was the lowest: 0.59 and 2.5 (L kg(-1)) for Gs and He respectively; whilst Cd (II) had the highest (130-135 L kg(-1)) for Gs. Roots showed a higher metal content than shoots. Translocation factors (TF) were lower, He was the plant exhibiting TFs>1 for Pb (II), Cr (T) and Hg (II) and 0.4-0.9 for Cd (II) and Cr (VI). The evaluated plants demonstrate their suitability for phytoremediation of landfill leachate and all of them can be categorized as metals accumulators. PMID:25174421

  8. Small scale recirculating vertical flow constructed wetland (RVFCW) for the treatment and reuse of wastewater.

    PubMed

    Gross, A; Sklarz, M Y; Yakirevich, A; Soares, M I M

    2008-01-01

    The quantity of freshwater available worldwide is declining, revealing a pressing need for its more efficient use. Moreover, in many developing countries and lightly populated areas, raw wastewater is discarded into the environment posing serious ecological and health problems. Unfortunately, this situation will persist unless low-cost, effective and simple technologies are brought in. The aim of this study is to present such a treatment method, a novel setup which is termed recirculating vertical flow constructed wetland (RVFCW). The RVFCW is composed of two components: (i) a three-layer bed consisting of planted organic soil over an upper layer of filtering media (i.e. tuff or beads) and a lower layer of limestone pebbles, and (ii) a reservoir located beneath the bed. Wastewater flows directly into the plant root zone and trickles down through the three-layer bed into the reservoir, allowing passive aeration. From the reservoir the water is recirculated back to the bed, several times, until the desired purification is achieved. The results obtained show that the RVFCW is an effective and convenient strategy to treat (domestic, grey and agro) wastewater for re-use in irrigation. The system performance is expected to be further improved once current optimization experiments and mathematical modeling studies are concluded. PMID:18701805

  9. Sulfate removal and sulfur transformation in constructed wetlands: The roles of filling material and plant biomass.

    PubMed

    Chen, Yi; Wen, Yue; Zhou, Qi; Huang, Jingang; Vymazal, Jan; Kuschk, Peter

    2016-10-01

    Sulfate in effluent is a challenging issue for wastewater reuse around the world. In this study, sulfur (S) removal and transformation in five batch constructed wetlands (CWs) treating secondary effluent were investigated. The results showed that the presence of the plant cattail (Typha latifolia) had little effect on sulfate removal, while the carbon-rich litter it generated greatly improved sulfate removal, but with limited sulfide accumulation in the pore-water. After sulfate removal, most of the S was deposited with the valence states S (-II) and S (0) on the iron-rich gravel surface, and acid volatile sulfide was the main S sink in the litter-added CWs. High-throughput pyrosequencing revealed that sulfate-reducing bacteria (i.e. Desulfobacter) and sulfide-oxidizing bacteria (i.e. Thiobacillus) were dominant in the litter-added CWs, which led to a sustainable S cycle between sulfate and sulfide. Overall, this study suggests that recycling plant litter and iron-rich filling material in CWs gives an opportunity to utilize the S in the wastewater as both an electron acceptor for sulfate reduction and as an electron donor for nitrate reduction coupled with sulfide oxidation. This leads to the simultaneous removal of sulfate, nitrate, and organics without discharging toxic sulfide into the receiving water body.

  10. Phytoremediation of domestic wastewaters in free water surface constructed wetlands using Azolla pinnata.

    PubMed

    Akinbile, Christopher O; Ogunrinde, Temitope A; Che Bt Man, Hasfalina; Aziz, Hamidi Abdul

    2016-01-01

    Two constructed wetlands, one with Azolla pinnata plant (CW1) and the other without (CW2) for treating domestic wastewaters were developed. Fifteen water parameters which include: Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Total Phosphorus (TP), Total Nitrogen (TN), Ammoniacal Nitrogen (NH3N), Turbidity, pH, Electrical Conductivity (EC), Iron (Fe), Magnesium (Mg), Manganese (Mn), and heavy metals such as Lead (Pb) and Zinc (Zn) were analyzed using standard laboratory procedures. The experiments were conducted in two (dry and wet) seasons simultaneously. Results showed considerable reductions in all parameters and metals including Zn in CW1 compared with CW2 in the two seasons considered while Pb and Mn were not detected throughout the study. Zn concentration levels reduced significantly in both seasons just as removal efficiencies of 70.03% and 64.51% were recorded for CW1 while 35.17% and 33.45% were recorded for CW2 in both seasons. There were no significant differences in the removal efficiencies of Fe in both seasons as 99.55%, 59.09%, 88.89%, and 53.56% were recorded in CW1 and CW2 respectively. Azolla pinnata has proved effective in domestic wastewater phytoremediation studies.

  11. [Effect of Intermittent Aeration on Nitrogen Removal Efficiency in Vertical Subsurface Flow Constructed Wetland].

    PubMed

    Wang, Jian; Li, Huai-zheng; Zhen, Bao-chong; Liu, Zhen-dong

    2016-03-15

    One-stage vertical subsurface flow constructed wetlands (CWs) were used to treat effluent from grit chamber in municipal wastewater treatment plant. The CW was divided into aerobic zone and anoxic zone by means of raising the effluent level and installing a perforated pipe. Two parameters (the ratio of aeration time and nonaeration time, aeration cycle) were optimized in the experiment to enhance nitrogen removal efficiency. The results suggested that the removal rates of COD and NH₄⁺-N increased while TN showed a trend of first increasing and then decreasing with the increasing ratio. When the ratio was 3:1, the C/N value in the anoxic zone was 4. 8. And the TN effluent concentration was 15.8 mg · L⁻¹ with the highest removal rate (62.1%), which was increased by 12.7% compared with continuous aeration. As the extension of the aeration cycle, the DO effluent concentration as well as the removal rates of COD and NH: -N declined gradually. The TN removal rate reached the maximum (65.5%) when the aeration cycle was 6h. However, the TN removal rate dropped rapidly when the cycle exceeded the hydraulic retention time in the anoxic zone. PMID:27337890

  12. Sediment and nutrient trapping efficiency of a constructed wetland near Delavan Lake, Wisconsin, 1993-1995

    USGS Publications Warehouse

    Elder, John F.; Goddard, Gerald L.

    1996-01-01

    Jackson Creek Wetland a 95-acre shallow prairie marsh containing three sediment retention ponds was constructed in 1992 to reduce sediment and nutrient in- flow to eutrophic Delavan Lake. The function of the wetland as a retention system for suspended sediments and nutrients (total and dissolved phosphorus, total ammonia plus organic nitrogen, dissolved ammonia, and nitrite plus nitrate nitrogen) was studied from February 1993 through September 1995. Input and output load computations were based on water flow (discharge) measurements and periodic sampling of suspended sediments and nutrients at the three inflowing streams and at the wetland outflow. Results of the study indicated consistent sediment retention throughout the year; at times, as much as 80 percent of the inflow load was retained in the wetland. Nutrient retention was generally of lesser magnitude and much more variable. Although the annual budgets confirm net retention for all nutrient forms except ammonia, data analysis over shorter time scales show that outflow loads actually can exceed inflow loads during the late spring and summer months the period of greatest likelihood of algal blooms in the lake. This result demonstrates that the nutrient-trapping function of the wetland is variable because of the complexity of the system. Awareness of such variability can help to maintain realistic expectations and effective management practices.

  13. 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.

  14. Modelling wet weather sediment removal by stormwater constructed wetlands: Insights from a laboratory study

    NASA Astrophysics Data System (ADS)

    Li, Y.; Deletic, A.; Fletcher, T. D.

    2007-05-01

    SummaryConstructed wetlands are now commonly used to control polluted urban stormwater discharges. A laboratory study was conducted to investigate the treatment of solids in these systems. Three mesocosm stormwater wetlands (vegetated with a well-established canopy of different densities) and one mesocosm non-vegetated pond were used, all sized to achieve particle fall number ( Nf, a ratio between the times of the particle travel in horizontal and vertical directions) and Particle Shear Velocity Reynolds Number, Re∗, which are reflective of full-scale systems. The mesocosm vegetated systems had also similar turbulent Reynolds Numbers ( ReT) to those funds in full-scale systems. Ten groups of steady-state experiments were carried out, all with different hydraulic loadings and sediment inflow concentrations (also maintained within the ranges found in real systems during wet weather). Samples were taken along the mesocosms and analysed for Total Suspended Solids concentrations (TSS) and Particle Size Distribution (PSD). It was found that both Re∗ and ReT do not significantly influence the trapping of sediments, and therefore the particle re-suspension induced by water flow is not important for sedimentation in constructed stormwater wetlands. Vegetation density was found not to be an important factor, while particle diameter, and flow characteristics (e.g., flow rate and velocity) do influence trapping efficiency of particles. It was concluded that sediment trapping correlates strongly with particle fall number, Nf, and therefore can be explained by this single non-dimensional number. A simple non-linear two-parameter regression model is proposed for prediction of particle trapping efficiency in constructed stormwater wetlands. However, further work is needed before the method can be used in practice. The aim of the ongoing work is to test whether the proposed model could be used across a number of real stormwater constructed wetlands without any further

  15. BPA and NP removal from municipal wastewater by tropical horizontal subsurface constructed wetlands.

    PubMed

    Toro-Vélez, A F; Madera-Parra, C A; Peña-Varón, M R; Lee, W Y; Bezares-Cruz, J C; Walker, W S; Cárdenas-Henao, H; Quesada-Calderón, S; García-Hernández, H; Lens, P N L

    2016-01-15

    It has been recognized that numerous synthetic compounds like Bisphenol A (BPA) and nonylphenols (NP) are present in effluents from wastewater treatment plants (WWTP) at levels of parts per billion (μg L(-1)) or even parts per trillion (ng L(-1)) with a high potential to cause endocrine disruption in the aquatic environment. Constructed wetlands (CW) are a cost-effective wastewater treatment alternative with promising performance to treat these afore mentioned compounds. This research was aimed to evaluate the efficacy of CW treatment of WWTP effluent for mitigating the effects endocrine disrupting compounds (EDCs). This research goal was accomplished by (1) quantifying the removal of BPA and NP in CWs; (2) isolating CW fungal strains and testing for laccase production; and (3) performing endocrine disruption (reproduction) bioassays using the fruit fly Drosophila melanogaster. Three pilot scale horizontal subsurface flow constructed wetlands (HSSF-CW) were operated for eight weeks: one planted with Phragmites australis; one planted with Heliconia psitacorum; and one unplanted. The Heliconia CW showed a removal efficiency of 73.3(± 19%) and 62.8(± 20.1%) for BPA and NP, respectively; while the Phragmites CW demonstrated a similar removal for BPA (70.2 ± 27%) and lower removal efficiency for NP 52.1(± 37.1%).The unplanted CW achieved 62.2 (± 33%) removal for BPA and 25.3(± 37%) removal for NP. Four of the eleven fungal strains isolated from the Heliconia-CW showed the capacity to produce laccase. Even though complete removal of EDCs was not achieved by the CWs, the bioassay confirmed a significant improvement (p < 0.05) in fly viability for all CWs, with Heliconia sp. being the most effective at mitigating adverse effects on first and second generational reproduction. This study showed that a CW planted with a native Heliconia sp. CW demonstrated a higher removal of endocrine disrupting compounds and better mitigation of reproductive disruption in the

  16. Distribution and Turnover of DOC in Natural and Constructed Wetlands in the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Stern, J. C.; Wang, Y.; Gu, B.

    2004-12-01

    Stable and radiocarbon isotopic contents of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and particulate organic carbon (POC) were used to examine the source and turnover rate of carbon in natural and constructed wetlands in the Florida Everglades. DOC concentrations decreased with decreasing phosphorus (P) concentrations along a water quality gradient from the agriculturally impacted areas in the northern Everglades to the more pristine Everglades National Park. δ 13C values of DOC in the area reflect contributions of both wetland vegetation and sugarcane from agriculture. Radiocarbon ages of DOC, POC and DIC in the Everglades ranged from 2010 years BP to ">modern". The old 14C ages of DOC and POC were found in impacted areas near the Everglade Agricultural Area (EAA) in the northern Everglades. In contrast, DOC and POC in pristine marsh areas had near modern or ">modern" 14C ages. These data indicate that a major source of POC and DOC in impacted areas is the degradation of historic peat deposits in the EAA. In the pristine areas of the marsh, DOC represents a mix of modern and historic carbon sources, whereas POC comes from modern primary production as indicated by positive Δ 14C values. High Δ 14C values of DIC indicate that dissolution of limestone is not a significant source of DIC in the Everglades wetlands. A 68.5% turnover of DOC from the northern to the southern Everglades was estimated using radiocarbon data. Our study suggests that Δ 14C measurements can be a useful indicator of the progress of ecosystem restoration in the Everglades. As a restored wetland moves towards its "original" or "natural" state, the 14C signatures of DOC should approach that of modern atmosphere. In addition, measurements of concentration and carbon isotopic composition of DOC in two small constructed wetland test cells indicate that these freshwater wetland systems contain a labile DOC pool with rapid turnover times and that the test cells are overall

  17. Modeling organic matter and nitrogen removal from domestic wastewater in a pilot-scale vertical subsurface flow constructed wetland.

    PubMed

    Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar; Castro-Faccetti, Claudia Fernanda

    2016-01-01

    Constructed wetlands have become an attractive alternative for wastewater treatment. However, there is not a globally accepted mathematical model to predict their performance. In this study, the VS2DTI software was used to predict the effluent biochemical oxygen demand (BOD) and total nitrogen (TN) in a pilot-scale vertical flow constructed wetland (VFCW) treating domestic wastewater. After a 5-week adaptation period, the pilot system was monitored for another 6 weeks. Experiments were conducted at hydraulic retention times (HRTs) in the range of 2-4 days with Typha latifolia as the vegetation. The raw wastewater concentrations ranged between 144-430 and 122-283 mg L(-1) for BOD5 and TN, respectively. A first-order kinetic model coupled with the advection/dispersion and Richards' equations was proposed to predict the removal rates of BOD5 and TN from domestic wastewater. Two main physical processes were modeled in this study, porous material water flow and solute transport through the different layers of the VFCW to simulate the constructed wetland (CW) conditions. The model was calibrated based on the BOD5 and TN degradation constants. The model indicated that most of BOD and TN (88 and 92%, respectively) were removed through biological activity followed by adsorption. It was also observed that the evapotranspiration was seen to have a smaller impact. An additional data series of effluent BOD and TN was used for model validation. The residual analysis of the calibrated model showed a relatively random pattern, indicating a decent fit. Thus, the VS2DTI was found to be a useful tool for CW simulation.

  18. 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.

  19. ASSESSING THE EFFECT OF ANTIBIOTICS ON THE RESISTANCE OF RESIDENT MICROBES IN WETLANDS CONSTRUCTED FOR WASTEWATER TREATMENT

    EPA Science Inventory

    The use of constructed wetlands as a cost effective and environmentally friendly option for wastewater treatment is becoming more prevalent. These systems are championed as combining many of the benefits of tertiary treatment while also providing high quality wetland habitat as...

  20. Comparative research on phosphorus removal by pilot-scale vertical flow constructed wetlands using steel slag and modified steel slag as substrates.

    PubMed

    Yun, Yupan; Zhou, Xiaoqin; Li, Zifu; Uddin, Sayed Mohammad Nazim; Bai, Xiaofeng

    2015-01-01

    This research mainly focused on the phosphorus removal performance of pilot-scale vertical flow constructed wetlands with steel slag (SS) and modified steel slag (MSS). First, bench-scale experiments were conducted to evaluate the phosphorus adsorption capacity. Results showed that the Langmuir model could better describe the adsorption characteristics of the two materials; the maximum adsorption of MSS reached 12.7 mg/g, increasing by 34% compared to SS (9.5 mg/g). Moreover, pilot-scale constructed wetlands with SS and MSS were set up outdoors. Then, the influence of hydraulic retention time (HRT) and phosphorus concentration in phosphorus removal for two wetlands were investigated. Results revealed that better performance of the two systems could be achieved with an HRT of 2 d and phosphorus concentration in the range of 3-4.5 mg/L; the system with MSS had a better removal efficiency than the one with SS in the same control operation. Finally, the study implied that MSS could be used as a promising substrate for wetlands to treat wastewater with a high phosphorus concentration. However, considering energy consumption, SS could be regarded as a better alternative for substrate when treating sewage with a low phosphorus concentration.

  1. 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

  2. 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.

  3. Do constructed wetlands in grass strips reduce water contamination from drained fields?

    PubMed

    Vallée, Romain; Dousset, Sylvie; Schott, François-Xavier; Pallez, Christelle; Ortar, Agnès; Cherrier, Richard; Munoz, Jean-François; Benoît, Marc

    2015-12-01

    This study evaluates the efficiency of two small constructed wetlands installed in the regulatory grass strips between a drained plot and a river. The observed nitrate removal efficiencies were independent of the season or type of constructed wetland and ranged from 5.4 to 10.9% of the inlet amounts. The pesticide mass budgets ranged from -618.5 to 100%, depending on the molecule. The negative efficiencies were attributed to runoff and remobilization. In contrast, the highest efficiencies were associated with pesticides with high Koc and low DT50 (half-life) values, suggesting sorption and degradation. However, the effectiveness of these wetlands is limited for pesticides with low Koc or high DT50 values; thus, the use of these molecules must be reduced. Increasing the number of these small, inexpensive and low-maintenance wetlands in the agricultural landscape would reduce the level of water pollution whilst preserving the extent of cultivated land, but their long-term effectiveness should be evaluated. PMID:26452003

  4. Do constructed wetlands in grass strips reduce water contamination from drained fields?

    PubMed

    Vallée, Romain; Dousset, Sylvie; Schott, François-Xavier; Pallez, Christelle; Ortar, Agnès; Cherrier, Richard; Munoz, Jean-François; Benoît, Marc

    2015-12-01

    This study evaluates the efficiency of two small constructed wetlands installed in the regulatory grass strips between a drained plot and a river. The observed nitrate removal efficiencies were independent of the season or type of constructed wetland and ranged from 5.4 to 10.9% of the inlet amounts. The pesticide mass budgets ranged from -618.5 to 100%, depending on the molecule. The negative efficiencies were attributed to runoff and remobilization. In contrast, the highest efficiencies were associated with pesticides with high Koc and low DT50 (half-life) values, suggesting sorption and degradation. However, the effectiveness of these wetlands is limited for pesticides with low Koc or high DT50 values; thus, the use of these molecules must be reduced. Increasing the number of these small, inexpensive and low-maintenance wetlands in the agricultural landscape would reduce the level of water pollution whilst preserving the extent of cultivated land, but their long-term effectiveness should be evaluated.

  5. [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.

  6. Methane and carbon dioxide emissions from constructed wetlands receiving anaerobically pretreated sewage.

    PubMed

    de la Varga, D; Ruiz, I; Álvarez, J A; Soto, M

    2015-12-15

    The aim of this research was to determine methane and carbon dioxide emissions from a hybrid constructed wetland (CW) treating anaerobically pre-treated sewage. The CW was constituted of two horizontal flow (free water surface followed by a subsurface) units. A long-term study was carried out as both CW units were monitored for three campaigns in Period 1 (0.9-1.5years after start-up), and four campaigns in Period 2 (4.5-5.8years after start-up). The closed chamber method with collecting surfaces of 1810cm(2) was used. For this system, variability due to position in the transverse section of CW, plant presence or absence and recommended sampling period was determined. Overall methane emissions ranged from 96 to 966mgCH4m(-2) d(-1), depending on several factors as the operation time, the season of the year and the position in the system. Methane emissions increased from 267±188mgCH4m(-2)d(-1) during the second year of operation to 543±161mgCH4m(-2)d(-1) in the sixth year of operation. Methane emissions were related to the age of the CW and the season of the year, being high in spring and becoming lower from spring to winter. Total CO2 emissions ranged mostly from 3500 to 5800mgCO2m(-2)d(-1) during the sixth year of operation, while nitrous oxide emissions were below the detection limit of the method.

  7. 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.

  8. Iron oxides stimulate microbial monochlorobenzene in situ transformation in constructed wetlands and laboratory systems.

    PubMed

    Schmidt, Marie; Wolfram, Diana; Birkigt, Jan; Ahlheim, Jörg; Paschke, Heidrun; Richnow, Hans-Hermann; Nijenhuis, Ivonne

    2014-02-15

    Natural wetlands are transition zones between anoxic ground and oxic surface water which may enhance the (bio)transformation potential for recalcitrant chloro-organic contaminants due to the unique geochemical conditions and gradients. Monochlorobenzene (MCB) is a frequently detected groundwater contaminant which is toxic and was thought to be persistent under anoxic conditions. Furthermore, to date, no degradation pathways for anoxic MCB removal have been proven in the field. Hence, it is important to investigate MCB biodegradation in the environment, as groundwater is an important drinking water source in many European countries. Therefore, two pilot-scale horizontal subsurface-flow constructed wetlands, planted and unplanted, were used to investigate the processes in situ contributing to the biotransformation of MCB in these gradient systems. The wetlands were fed with anoxic MCB-contaminated groundwater from a nearby aquifer in Bitterfeld, Germany. An overall MCB removal was observed in both wetlands, whereas just 10% of the original MCB inflow concentration was detected in the ponds. In particular in the gravel bed of the planted wetland, MCB removal was highest in summer season with 73 ± 9% compared to the unplanted one with 40 ± 5%. Whereas the MCB concentrations rapidly decreased in the transition zone of unplanted gravel to the pond, a significant MCB removal was already determined in the anoxic gravel bed of the planted system. The investigation of hydro-geochemical parameters revealed that iron and sulphate reduction were relevant redox processes in both wetlands. In parallel, the addition of ferric iron or nitrate stimulated the mineralisation of MCB in laboratory microcosms with anoxic groundwater from the same source, indicating that the potential for anaerobic microbial degradation of MCB is present at the field site.

  9. 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).

  10. 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.

  11. Rural Sewage Treatment by using Combined Process of Multi-layer Bio-filter and Constructed Wetland

    NASA Astrophysics Data System (ADS)

    Li, Xudong; Paul, Etienne; Qiu, Jiangping; Roustan, Michel; Wisniewski, Christelle; Mauviot, Patrice

    2010-11-01

    A combined process of multi-layer bio-filter and constructed wetland has been used to treat the rural sewage in eastern China. The capacity of the system was 60 m3/d, the hydraulic loading rate (HLR) of the bio-filter and the constructed wetland was 4.0 m3/(m3ṡd) and 0.50 m3/(m3ṡd), respectively. The system has been operated automatically for 2 years. The results showed that the average concentrations of COD, NH4+-N, TN and TP in the effluent were 58.2, 8.1, 12.1 and 0.9 mg/L with the removal efficiency of 79.2%, 62.8%, 55.1% and 77.1% respectively, which could meet the first grade of Chinese national pollutants discharge standard for municipal wastewater treatment plant (GB 18918-2002). The track studies showed that the organic pollutants were mainly removed in the first 4 layers and the ammonia was mainly removed in the 4th˜6th layers of the filter. It was observed that the COD removal efficiency in the whole system decreased from 84.6% to 73.3% following the sequences of summer, autumn, spring and winter. Comparing with traditional techniques, the combined process could provide a higher nitrogen and phosphorus removal capacity.

  12. Distribution of ammonium-N in the water-soil interface of a surface-flow constructed wetland for swine wastewater treatment.

    PubMed

    Szögi, A A; Hunt, P G

    2001-01-01

    Most livestock wastewaters treated in constructed wetlands are typically rich in ammonium N. The objective of this study was to evaluate the soil-water ammonium distribution and the diffusive flux through the soil-water interface. Wetland system 1 (WS1) was planted to rush and bulrushes, and wetland system 2 (WS2) was planted to bur-reed and cattails. Nitrogen was applied at a rate of 2.5 g m(-2) d(-1). Interstitial soil water was sampled at 9, 24, 50, and 70 m from the inlet. In both wetlands, we found that NH4+ diffusion gradient and N losses were highest in the wetland system with lowest water depth. From other studies, we knew that shallower depths may have promoted a more effective interfacing of nitrifying and denitrifying environments. In turn, this N reduction in the water column may be the reason for steady NH4+-N upward diffusion fluxes. The assumed mechanism for N removal has been nitrification and denitrification but ammonia volatilization could also have occurred. Although diffusion may explain a significant portion of the material transport between the soil-water interface, the large differences in concentrations between outlet and inlet need further explanation.

  13. The Spatial Distribution of Nitrogen Removal Functional Genes in Multimedia Constructed Wetlands for Wastewater Treatment.

    PubMed

    Ji, Guodong; He, Chunguang; Tan, Yufei; Yang, Zhonghua

    2015-11-01

    The real-time polymerase chain reaction was used to quantitatively evaluate distribution patterns and nitrogen removal pathways of the amoA, nxrA, narG, napA, nirK, qnorB, nosZ, nas, and nifH genes and 16S rRNA in anaerobic ammonia oxidation bacteria in four multimedia constructed wetlands for rural wastewater treatment. The results indicated that the abundance of functional genes for nitrogen removal in the rhizosphere layer (0 to 30 cm), water distribution layer (30 to 50 cm), multime filler layer (50 to 130 cm), and catchment layer (130 to 170 cm) of the constructed wetlands were closely related. The rhizosphere layer was conducive to the absolute enrichment of dominant genes. The other three layers were favorable to the relative enrichment of rare genes. PMID:26564582

  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. PMID:20933388

  15. 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.

  16. The Spatial Distribution of Nitrogen Removal Functional Genes in Multimedia Constructed Wetlands for Wastewater Treatment.

    PubMed

    Ji, Guodong; He, Chunguang; Tan, Yufei; Yang, Zhonghua

    2015-11-01

    The real-time polymerase chain reaction was used to quantitatively evaluate distribution patterns and nitrogen removal pathways of the amoA, nxrA, narG, napA, nirK, qnorB, nosZ, nas, and nifH genes and 16S rRNA in anaerobic ammonia oxidation bacteria in four multimedia constructed wetlands for rural wastewater treatment. The results indicated that the abundance of functional genes for nitrogen removal in the rhizosphere layer (0 to 30 cm), water distribution layer (30 to 50 cm), multime filler layer (50 to 130 cm), and catchment layer (130 to 170 cm) of the constructed wetlands were closely related. The rhizosphere layer was conducive to the absolute enrichment of dominant genes. The other three layers were favorable to the relative enrichment of rare genes.

  17. 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.

  18. 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.

  19. 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. PMID:25813638

  20. Effect of recirculation on organic matter removal in a hybrid constructed wetland system.

    PubMed

    Ayaz, S C; Findik, N; Akça, L; Erdoğan, N; Kinaci, C

    2011-01-01

    This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 +/- 4% for COD, 83 +/- 10% for BOD and 96 +/- 3% for suspended solids with average effluent concentrations of 9 +/- 5 mg/L COD, 6 +/- 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities. PMID:21977661

  1. Phytoremediation of explosives contaminated ground waters by plant enzyme systems in constructed wetlands

    SciTech Connect

    Jackson, R.P. Jr.

    1995-12-31

    A plant enzyme system has successfully degraded the explosives TNT, RDX, and HMX to environmentally acceptable products during laboratory studies. The process has been further studied in the field in batch systems. The field results have been consistent with the laboratory findings. An artificial wetlands will be constructed to remediate explosives contaminated ground water at an Army ammunition plant. An overview of the phytoremediation program will be presented.

  2. 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.

  3. The Bark Camp Run demonstration constructed wetlands: Findings and recommendations for future design criteria

    SciTech Connect

    Hellier, W.W.

    1996-12-31

    The performance of six wetlands built to ameliorate acid mine drainage has been analyzed over 806 days. The wetlands are each 52 m x 8 m at the water surface, with a 5 cm surface water column and 60 cm depth of substrate consisting of horse manure mixed with an equal volume of SiO{sub 2} stone. Each wetland has a 1 mm polyethylene liner and wooden deflectors ever 2 m to promote uniform flow. The dominant macrophyte is Typha latifolia. Flows are {approximately}10 m{sup 3}/d. Tracer studies showed that the mine drainage flows through both the surface water column and the substrate, and a one-dimensional flow model appears satisfactorily to explain the performance of the wetlands. Wetlands should be designed to achieve uniform flow and to maintain flow through the substrate A polishing area of a few m{sup 2} with a substrate consisting only of limestone chips appears to be helpful in maintaining effluent alkalinity. Simple mathematical models were developed to assess the performance of the constructed wetlands. Removal of Fe{sup +3} is by hydrolysis, followed by reduction to Fe{sup 2+} and incorporation into the substrate. Removal of Al{sup +3} is by hydrolysis. The observed removal rates of 1g d{sup -1} m{sup -2} for Fe{sup +3} and 0.5g d{sup -1} m{sup -2} for Al{sup +3}, combine with concurrent neutralization of the resulting H{sup +}, to give an acidity removal rate of 5.5g d{sup -1} m{sup -2}. A zero-order rate law can be used to describe the observed rate of Fe{sup +3} removal First-order rate laws also produce good representations for the rates of Fe{sup +3} and Al{sup +3} removal. Effluent Mn concentration > influent [Mn], and declines in accordance with a first-order rate law, indicative of desorption of Mn{sup 2+} initially present in the substrate. This may explain past difficulties in assessing Mn removal in anaerobic constructed wetlands.

  4. Application of Pseudomonas flava WD-3 for sewage treatment in constructed wetland in winter.

    PubMed

    Tang, Meizhen; Zhang, Fengfeng; Yao, Shumin; Liu, Yuling; Chen, Junfeng

    2015-01-01

    Recently, constructed wetland was applied for sewage treatment globally due to its high efficiency and relatively low investment. However, operation of many constructed wetlands in cold winter is quite difficult due to the inhibition effect of low temperature. The objective of this experiment is to study the sewage treatment efficiency of Pseudomonas flava WD-3 in the integrated vertical-flow constructed wetland (IVCW) during winter with different dosages (bacterial suspension concentration: 4.575×10(8 )mL(-1)). Two treatments were designed, inoculation of P. flava WD-3 with different dosages and the control without bacterium incubation. A simplified Monod model was applied to simulate and evaluate the pollutant removal efficiency of this bacterial strain with respect to its dosages. Results indicated that P. flava WD-3 could degrade organic pollutants, nitrogen, and phosphorus nutrients from wastewater effectively. The optimal dosage of this strain was 6.0%, and the removal rates of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), and total phosphorous (TP) were 85.82-87.00%, 73.91-84.18%, and 82.04-87.00%, respectively. Furthermore, the average removal efficiencies of COD, NH4+-N, and TP were 1.46, 1.49, and 1.76 times, respectively, than the control. The simplified Monod model accurately predicted the pollutant removal efficiency of P. flava WD-3 in the IVCW system in winter.

  5. Twenty years experience with constructed wetland systems in Denmark--what did we learn?

    PubMed

    Brix, H; Schierup, H H; Arias, C A

    2007-01-01

    Full scale constructed wetland systems for wastewater treatment have been in operation in Denmark since 1983, mainly for the treatment of domestic sewage from small villages. The systems are constructed as soil-based horizontal subsurface flow systems but, because of low soil hydraulic conductivity, surface runoff is evident in most of the systems. Two decad