Heavy metal removal within pilot-scale constructed wetlands receiving river water contaminated by confined swine operations

This study demonstrated heavy metal removal from neutral mine drainage of a closed mine in Kyoto prefecture in pilot-scale constructed wetlands (CWs). The CWs filled with loamy soil and limestone were unplanted or planted with cattails. The hydraulic retention time (HRT) in the CWs was shortened gradually from 3.8 days to 1.2 days during 3.5 months of operation. A short HRT of 1.2 days in the CWs was sufficient to achieve the effluent standard for Cd (0.03 mg/L). The unplanted and the cattail-planted CWs reduced the average concentrations of Cd from 0.031 to 0.01 and 0.005 mg/L, Zn from 0.52 to 0.14 and 0.08 mg/L, Cu from 0.07 to 0.04 and 0.03 mg/L, and As from 0.011 to 0.006 and 0.006 mg/L, respectively. Heavy metals were removed mainly by adsorption to the soil in both CWs. The biological concentration factors in cattails were over 2 for Cd, Zn, and Cu. The translocation factors of cattails for all metals were 0.5–0.81. Sulfate-reducing bacteria (SRB) belonging to Deltaproteobacteria were detected only from soil in the planted CW. Although cattails were a minor sink, the plants contributed to metal removal by rhizofiltration and incubation of SRB, possibly producing sulfide precipitates in the rhizosphere.

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Growth and metal removal efficiency of the green algae Schroederia setigera and Selenastrum bibraianum exposed to nickel, zinc and cadmium

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/58/5a/15183 ◽

2020 ◽

Vol 58 (5A) ◽

pp. 22

Author(s):

Dao Thanh Son ◽

Van Tai Nguyen ◽

Thuy Nhu Quynh Vo ◽

Vinh Quang Tran ◽

Thi My Chi Vo ◽

...

Keyword(s):

Heavy Metal ◽

Green Algae ◽

Removal Efficiency ◽

Heavy Metal Contamination ◽

Metal Removal ◽

Heavy Metal Removal ◽

Pilot Scale ◽

Nickel Zinc ◽

Ecological Protection

Heavy metal contamination is among the globally environmental and ecological concerns. In this study we assessed the development of the two green algae Schroederia setigera and Selenastrum bibraianum under exposures to 5 – 200 µg/L of Ni, Zn, and Cd in the laboratory conditions. Heavy metal removal efficiency of S. setigera was also tested in 537 µg Ni/L, 734 µg Zn/L, and 858 µg Cd/L. We found that the exposures with these heavy metals caused inhibitory on the growth of S. bibraianum. The S. bibraianum cell size in the 200 µg Zn/L treatment was around two times smaller than the control. However, Zn and Cd at the concentration of 200 µg/L did not inhibit the growth of S. setigera over 18 days of exposure. The S. setigera also grew well during 8 days exposed to Ni at the same concentration. Besides, the alga S. setigera could remove 66% of Zn, 18% of Cd and 12% of Ni out of the test medium after 16 days of incubation. The Vietnam Technical Regulation related to metals should be considered for ecological protection. We recommend to test the metal removal by the alga S. setigera at pilot scale prior to apply it in situ

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Constructed wetlands: fundamental processes and mechanisms for heavy metal removal from wastewater streams

International Journal of Environmental Engineering ◽

10.1504/ijee.2016.10003208 ◽

2016 ◽

Vol 8 (2/3) ◽

pp. 148

Author(s):

Richard J. Haynes ◽

Tao Hua

Keyword(s):

Heavy Metal ◽

Constructed Wetlands ◽

Metal Removal ◽

Heavy Metal Removal

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Heavy metal removal from winery wastewater in the case of restrictive discharge regulation

Water Science & Technology ◽

10.2166/wst.2007.479 ◽

2007 ◽

Vol 56 (2) ◽

pp. 111-120 ◽

Cited By ~ 11

Author(s):

G. Andreottola ◽

M. Cadonna ◽

P. Foladori ◽

G. Gatti ◽

F. Lorenzi ◽

...

Keyword(s):

Heavy Metal ◽

Metal Removal ◽

Heavy Metal Removal ◽

Chemical Precipitation ◽

Pilot Scale ◽

Winery Wastewater ◽

Removal Of Heavy Metals ◽

Discharge Regulation ◽

Pre Treatment ◽

Cu And Zn

In most cases of winery effluent, the heavy metal content, especially zinc (Zn) and copper (Cu), does not meet the limits for the discharge as imposed by the most restrictive regulations at international level (0.4 mgCu/L and 1.0 mgZn/L in the Italian regulations). An alternative for the reduction of Cu and Zn is the on-site pre-treatment of wastewater at the winery in order to meet the limits for the discharge into the public sewerage. The purpose of this study is to evaluate the effectiveness of a pre-treatment based on chemical precipitation with chelating agents (TMT: 2,4,6-trimercaptotriazine), for the reduction of Cu and Zn from raw winery wastewater. The chemical precipitation was optimised at lab-scale through jar tests in order to evaluate the optimal dosages. An average dosage equal to 0.84 mL of TMT (15%) for 1 mg of Cu removed was estimated. Furthermore, the efficiency of the on-site chemical pre-treatment was investigated at pilot scale. The results confirmed the feasibility of using TMT treatment for the reduction of Cu and Zn in order to meet the limits for discharge into the sewerage. Contextually to the removal of heavy metals, the chemical pre-treatment allowed us to obtain the reduction of particulate COD and TSS. Finally, the costs for the operation and the management of the on-site pre-treatment were evaluated.

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Development of the data-driven models for accessing the impact of design variables on heavy metal removal in constructed wetlands

Blue-Green Systems ◽

10.2166/bgs.2021.024 ◽

2021 ◽

Author(s):

Jiadong Zhang ◽

Veljko Prodanovic ◽

Anna Lintern ◽

Kefeng Zhang

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Constructed Wetlands ◽

Green Infrastructure ◽

Linear Mixed Model ◽

Metal Removal ◽

Heavy Metal Removal ◽

Influential Factors ◽

Design Variables ◽

The Impact

Abstract Constructed wetlands are a type of green infrastructure commonly used for urban stormwater treatment. Previous studies have shown that the various design characteristics have an influence on the outflow heavy metal concentrations. In this study, we develop a Bayesian linear mixed model (BLMM) and a Bayesian linear regression model (BLRM) to predict the outflow concentrations of heavy metals (Cd, Cu, Pb and Zn) using an inflow concentration (Cin) and five design variables, namely media type, constructed wetland type (CWT), hydraulic retention time, presence of a sedimentation pond (SedP) and wetland-to-catchment area ratio (Ratio). The results show that the BLMM had much better performance, with the mean Nash–Sutcliffe efficiency between 0.51 (Pb) and 0.75 (Cu) in calibration and between 0.28 (Pb) and 0.71 (Zn) in validation. The inflow concentration was found to have significant impacts on the outflow concentration of all heavy metals, while the impacts of other variables on the wetland performance varied across metals, e.g., CWT and SedP showed a positive correlation to Cd and Cu, whereas media and Ratio were negatively correlated with Pb and Zn. Results also show that the 100-fold calibration and validation was superior in identifying the key influential factors.

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