Reducing phosphorus flux from organic soils in surface flow treatment wetlands

The larger aquatic plants growing in wetlands are usually called macrophytes. These include aquatic vascular plants, aquatic mosses and some larger algae. The presence or absence of aquatic macrophytes is one of the characteristics used to define wetlands, and as such macrophytes are an indispensable component of these ecosystems. As the most important removal processes in constructed treatment wetlands are based on physical and microbial processes, the role of the macrophytes in these has been questioned. This paper summarizes how macrophytes influence the treatment processes in wetlands. The most important functions of the macrophytes in relation to the treatment of wastewater are the physical effects the presence of the plants gives rise to. The macrophytes stabilise the surface of the beds, provide good conditions for physical filtration, prevent vertical flow systems from clogging, insulate the surface against frost during winter, and provide a huge surface area for attached microbial growth. Contrary to earlier belief, the growth of macrophytes does not increase the hydraulic conductivity of the substrate in soil-based subsurface flow constructed wetlands. The metabolism of the macrophytes affects the treatment processes to different extents depending on the type of the constructed wetland. Plant uptake of nutrients is only of quantitative importance in low-loaded systems (surface flow systems). Macrophyte mediated transfer of oxygen to the rhizosphere by leakage from roots increases aerobic degradation of organic matter and nitrification. The macrophytes have additional site-specific values by providing habitat for wildlife and making wastewater treatment systems aesthetically pleasing.

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Contaminant removal efficiency depending on primary treatment and operational strategy in horizontal subsurface flow treatment wetlands

Ecological Engineering ◽

10.1016/j.ecoleng.2010.12.011 ◽

2011 ◽

Vol 37 (2) ◽

pp. 372-380 ◽

Cited By ~ 39

Author(s):

Anna Pedescoll ◽

Angélica Corzo ◽

Eduardo Álvarez ◽

Jaume Puigagut ◽

Joan García

Keyword(s):

Removal Efficiency ◽

Subsurface Flow ◽

Primary Treatment ◽

Treatment Wetlands ◽

Contaminant Removal ◽

Operational Strategy ◽

Horizontal Subsurface Flow ◽

Flow Treatment

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Resilience and reliability of compact vertical-flow treatment wetlands designed for tropical climates

The Science of The Total Environment ◽

10.1016/j.scitotenv.2018.06.036 ◽

2018 ◽

Vol 642 ◽

pp. 208-215 ◽

Cited By ~ 8

Author(s):

R. Lombard-Latune ◽

L. Pelus ◽

N. Fina ◽

F. L'Etang ◽

B. Le Guennec ◽

...

Keyword(s):

Treatment Wetlands ◽

Vertical Flow ◽

Tropical Climates ◽

Flow Treatment

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Assessment of spatial representativity of X-ray tomography to study Vertical Flow Treatment wetlands

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.136510 ◽

2020 ◽

Vol 713 ◽

pp. 136510 ◽

Cited By ~ 1

Author(s):

German Dario Martinez-Carvajal ◽

Laurent Oxarango ◽

Rémi Clément ◽

Pascal Molle ◽

Nicolas Forquet

Keyword(s):

Treatment Wetlands ◽

Vertical Flow ◽

X Ray ◽

Flow Treatment

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Residential subsurface flow treatment wetlands in northern Minnesota

Water Science & Technology ◽

10.2166/wst.2001.0850 ◽

2001 ◽

Vol 44 (11-12) ◽

pp. 345-352 ◽

Cited By ~ 4

Author(s):

R. Axler ◽

J. Henneck ◽

B. McCarthy

Keyword(s):

System Performance ◽

High Strength ◽

Treatment Wetlands ◽

Site Conditions ◽

Vegetation Growth ◽

N Removal ◽

Regulatory Standards ◽

Rain Events ◽

Flow Treatment ◽

Spring Snowmelt

Approximately 30% of Minnesotans use on-site systems (~500,000 residences) and >50% are failing or non-compliant with regulations due to restrictive soils and site conditions. Many sites occur near lakes and streams creating health hazards and deteriorating water quality. SSF CWs have been evaluated year-round at two northern sites since 1995. The NERCC CWs simulate single homes and the Grand Lake demonstration CW treats STE from a cluster of 9 lakeshore homes. Systems were generally able to achieve design criteria of 25 mgTSS/L and 30 mgBOD5/L and the NERCC CWs required only 0.3m of unsaturated soil to achieve consistent disinfection to <200 fecals/100 mL year round. Seeding experiments with Salmonella indicated removal efficiencies of 99.8% in summer and 95% in winter. High strength (∼300 mgBOD/L, 95 mgTN/L) influent at NERCC probably limited system performance, particularly N-removal (mass) which was ∼42% in summer and 20% in winter. The data indicate CW's are a viable, year-round treatment option for homeowners in terms of performance, ease of operation, and cost but require additional maintenance related to inconsistent vegetation growth, winter insulation, and meeting concentration-based regulatory standards since they were seasonally and annually variable due to rain events, partial freezing, spring snowmelt, and summer evapotranspiration.

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French vertical flow treatment wetlands in a subtropical climate: Characterization of the organic deposit layer and comparison with systems in France

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.140608 ◽

2020 ◽

Vol 742 ◽

pp. 140608

Author(s):

Camila Maria Trein ◽

Camille Banc ◽

Kevin Maciejewski ◽

Amanda de Moraes Motta ◽

Rémy Gourdon ◽

...

Keyword(s):

Treatment Wetlands ◽

Subtropical Climate ◽

Vertical Flow ◽

Flow Treatment ◽

Deposit Layer ◽

Organic Deposit

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ALKALINITY GENERATION AND METALS RETENTION IN VERTICAL-FLOW TREATMENT WETLANDS

Journal American Society of Mining and Reclamation ◽

10.21000/jasmr00010412 ◽

2000 ◽

Vol 2000 (1) ◽

pp. 412-420 ◽

Cited By ~ 1

Author(s):

Robert W. Nairn ◽

Matthew N. Mercer ◽

Stephanie A. Lipe

Keyword(s):

Treatment Wetlands ◽

Vertical Flow ◽

Alkalinity Generation ◽

Flow Treatment

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Partitioning of heavy metals in sub-surface flow treatment wetlands receiving high-strength wastewater

Water Science & Technology ◽

10.2166/wst.2013.283 ◽

2013 ◽

Vol 68 (2) ◽

pp. 486-493 ◽

Cited By ~ 4

Author(s):

Ewa Wojciechowska ◽

Magdalena Gajewska

Keyword(s):

Heavy Metals ◽

Metal Removal ◽

High Strength ◽

Pilot Scale ◽

Surface Flow ◽

Treatment Wetlands ◽

Treated Wastewater ◽

Upward Movement ◽

Below Ground ◽

Co Precipitation

The retention of heavy metals at two pilot-scale treatment wetlands (TWs), consisting of two vertical flow beds (VSSF) followed by a horizontal flow bed (HSSF) was studied. The TWs received high-strength wastewater: reject waters from sewage sludge centrifugation (RW) and landfill leachate (LL). The concentrations of the metals Fe, Mn, Zn, Al, Pb, Cu, Cd, Co, and Ni were measured in treated wastewater, substrate of the beds and in plant material harvested from the beds (separately in above ground (ABG) parts and below ground (BG) parts). The TWs differed in metals retention. In the RW treating TW the metal removal efficiencies varied from 27% for Pb to over 97% for Fe and Al. In the LL treating system the concentrations of most metals decreased after VSSF-1 and VSSF-2 beds; however, in the outflow from the last (HSSF) bed, the concentrations of metals (apart from Al) increased again, probably due to the anaerobic conditions at the bed. A major removal pathway was sedimentation and adsorption onto soil substrate as well as precipitation and co-precipitation. In the LL treating facility the plants contained substantially higher metal concentrations in BG parts, while the upward movement of metals was restricted. In the RW treating facility the BG/ABG ratios were lower, indicating that metals were transported to shoots.

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