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

Specht, W.L.

doi:10.2172/799419

Cited by 7 publications

(15 citation statements)

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“…Our results agree with previous studies conducted on the A‐01 WTS and other constructed wetlands (Nelson et al, 2002; Specht and Nelson, 2002; Knox et al, 2004; Mitsch and Wise, 1998), which indicate that substratum (sediment) is the primary sink for metals in constructed wetland treatment systems. Metal concentrations in the A‐01 WTS were greater in the surface layers of sediments, which are rich in organic matter.…”

Section: Discussionsupporting

confidence: 93%

“…A layer (about 20 cm) of this soil was added to the cells, then amendments were added, and an additional 20‐cm layer of the soil was added. The following amendments were mixed with the soil when the wetland treatment cells were constructed: organic matter (primarily coarse wood chips), fertilizer (Osmocote, 14‐13‐14 formula) at the rate of 3920 kg ha −1 (1.75 tons acre −1 ), and gypsum at the rate of 2240 kg ha −1 (1 ton acre −1 ) (Specht and Nelson, 2002). The treatment system was constructed during the winter/spring of 2000 and began receiving A‐01 effluent in July 2000.…”

Section: Methodsmentioning

confidence: 99%

“…Additional water samples have been collected at numerous locations from the inflow of the system through the discharge to the receiving stream for research purposes (Nelson et al, 2002; Knox et al, 2004). Sediment samples were collected and analyzed to provide baseline data on metal concentrations and general sediment chemistry early in the operational life of the treatment system in September 2001 (Specht and Nelson, 2002). Additional sediment samples from two wetland cells (4A and 4B) were collected in June 2004 and 2005, and these data are the subject of this paper.…”

Section: Methodsmentioning

confidence: 99%

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Metal Distribution and Stability in Constructed Wetland Sediment

et al. 2006

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The A-01 wetland treatment system (WTS) is a surface flow wetland planted with giant bulrush [Schoenoplectus californicus (C.A. Mey.) Palla] that is designed to remove Cu and other metals from the A-01 National Pollution Discharge Elimination System (NPDES) effluent at the Savannah River Site near Aiken, SC. Copper, Zn, and Pb concentrations in water were usually reduced 60 to 80% by passage through the treatment system. The Cu concentrations in the wetland sediments increased from about 4 to 205 and 796 mg kg(-1), respectively, in the organic and floc sediment layers in cell 4A over a 5-yr period. Metal concentrations were higher in the two top layers of sediment (i.e., the floc and organic layers) than in the deeper inorganic layers. Sequential extraction was used to evaluate remobilization and retention of Cu, Pb, Zn, Mn, and Fe in the wetland sediment. Metal remobilization was determined by the potentially mobile fraction (PMF) and metal retention by the recalcitrant factor (RF). The PMF values were high in the floc layer but comparatively low in the organic and inorganic layers. High RF values for Cu, Zn, and Pb in the organic and inorganic layers indicated that these metals were strongly bound in the sediment. The RF values for Mn were lower than for the other elements especially in the floc layer, indicating low retention or binding capacity. Retention of contaminants was also evaluated by distribution coefficient (Kd) values. Distribution coefficient (Kd) values were lower for Cu and Zn than for Pb, indicating a smaller exchangeable fraction for Pb.

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Section: Discussionsupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Metal Distribution and Stability in Constructed Wetland Sediment

et al. 2006

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“…Sediment sampling at 8 locations along the water course of a pair of wetland cells was conducted in September 2001 (Specht and Nelson, 2002). Samples were analyzed for metals in the surface layer (0-1 cm) of sediment and in deeper sediments (1-10 cm) by EPA method 2007.…”

Section: Resultsmentioning

confidence: 99%

“…The sediments were sampled and analyzed to identify the copper distribution. Most of the copper was found in the upper 5 cm of the sediments and organic layer in the first half of the A cell (Specht and Nelson, 2002). Most of the divalent metals are rapidly removed from the water and held shortly after making contact with treatment wetlands.…”

Section: Resultsmentioning

confidence: 99%

Full-scale treatment wetlands for metal removal from industrial wastewater

Nelson

Gladden

2008

Environ. Geosci.

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AcknowledgementsThis research was conducted and the document was prepared in connection with work under U.S. Department of Energy contract DE-AC09-96SR18500. Extensive collaboration with Clemson University and Weston Engineering were essential during the design and construction phases of the wetland facility. AbstractThe A-01 NPDES outfall at the Savannah River Site receives process wastewater discharges and stormwater runoff from the Savannah River National Laboratory. Routine monitoring indicated that copper concentrations were regularly higher than discharge permit limit, and water routinely failed toxicity tests. These conditions necessitated treatment of nearly one million gallons of water per day plus storm runoff. Washington Savannah River Company personnel explored options to bring process and runoff waters into compliance with the permit conditions, including source reduction, engineering solutions, and biological solutions. A conceptual design for a constructed wetland treatment system (WTS) was developed and the full-scale system was constructed and began operation in 2000. The overall objective of our research is to better understand the mechanisms of operation of the A-01 WTS in order to provide better input to design of future systems. The system is a vegetated surface flow wetland with a hydraulic retention time of approximately 48 hours. Copper, mercury, and lead removal efficiencies are very high, all in excess of 80% removal from water passing through the wetland system. Zinc removal is 60%, and nickel is generally unaffected. Dissolved organic carbon in the water column is increased by the system and reduces toxicity of the effluent. Concentrations of metals in the A-01 WTS sediments generally decrease with depth and along the flow path through the wetland. Sequential extraction results indicate that most metals are tightly bound to wetland sediments. IntroductionThe ability of natural wetlands to improve many aspects of water quality has been recognized for many years. This natural process has been utilized in many different forms and applications to use constructed treatment wetlands for the purpose of water quality improvement (Moshiri, 1993; Kadlec and Knight, 1996;Hammer, 1989;Shutes, 2001). One aspect of natural wetland functions that has been capitalized on is the biogeochemical cycling and storage processes that occur in the systems. Heavy metal retention by constructed and natural wetlands has been used effectively in mining regions of the USA and Europe to reduce levels of Cu, Zn, Ni, Pb, and other metals in runoff and drainage (Mays and Edwards, 2001;Sobolewski, 1999). They are equally effective at treating stormwater runoff with high metal concentrations (Walker and Hurl, 2002;Carleton et al., 2001;Scholes et al., 1998).Removal of metals from the water occurs by two primary mechanisms: sorption and precipitation. Sorption of metal ions to organic matter and/or clay particles begins immediately.

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Metal Removal from Water Discharges by a Constructed Treatment Wetland

2006

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A full‐scale constructed wetland treatment system consisting of four pairs of wetland cells (3.2 ha total area) with water flowing through a pair of cells in series prior to discharge was investigated. A retention basin provided stable water flow to the system. Water retention time in the wetland system was approximately 48 hours, and the wetland cells operated at circumneutral pH. Vegetation development within the cells has been excellent. Copper removal efficiency was greater than 75 % from the start‐up of the system, while mercury efficiency improved with maturation of the treatment cells. Sampling of the water course through the wetlands conducted during the fourth year of operation validated continued performance, and assessed the fate of a larger suite of metals present in the water. Copper and mercury removal efficiencies were still very high, both in excess of 80 % removal from the water after passage through the wetland system. Mercury removal continued along the entire water course through the system, while copper was removed almost immediately upon entering the wetland cells. Lead removal from the water by the system was 83 %, zinc removal was 60 %, and nickel was generally unaffected. Organic carbon in the water was also increased by the system and reduced the bioavailability of some metals. Operation and maintenance of the system continued to be minimal, and mainly consisted of checking for growth of the vegetation and free flow of the water through the system. The system was entirely passive, relying on gravity as the power source of water flow. No reportable permit exceedances have been experienced since the wetland began treating an outfall discharge.

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

Cited by 7 publications

References 0 publications

Metal Distribution and Stability in Constructed Wetland Sediment

Metal Distribution and Stability in Constructed Wetland Sediment

Full-scale treatment wetlands for metal removal from industrial wastewater

Metal Removal from Water Discharges by a Constructed Treatment Wetland

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