| 1. |
- Khokhotva, Oleksandr, et al.
(författare)
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The influence of dissolved organic carbon on sorption of heavy metals on urea-treated pine bark
- 2010
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Ingår i: Journal of Hazardous Materials. - Amsterdam : Elsevier. - 0304-3894 .- 1873-3336. ; 173:1-3, s. 689-696
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Tidskriftsartikel (refereegranskat)abstract
- A previous study showed considerably higher metal adsorption by urea-treated pine bark (UTB) compared to non-treated bark (NTB) at metal adsorption from their individual relatively concentrated solutions. Comparison of the sorption characteristics of the two pine barks at low but environmentally relevant metal concentrations, and investigation of the influence of pH and dissolved organic carbon (DOC) on the sorption process are the aims of the present study. Sorption of Cu2+, Ni2+, Zn2+ and Pb2+ on pine bark of the species Pinus sylvestris was measured in multi-metal solutions in the presence and absence of DOC. In the absence of DOC, UTB gave lower residual metal concentrations (2–7 μg/l for copper, 1–5 μg/l for nickel, <0.05 μg/l for zinc and lead) in the range of initial concentrations up to 0.7 mg/l, compared to NTB (6–15 μg/l for copper, 2–24 μg/l for nickel, 2–9 μg/l for zinc, 2–3 μg/l for lead). In the presence of DOC, sorption of Zn, Ni and Pb decreased by up to 75% depending on the DOC concentration. Metal sorption on UTB is less sensitive to pH and more adsorbed metal ions are retained compared to NTB. The potential use of urea-treated bark for treatment of waste water containing DOC and low concentrations of metals is discussed. © 2009 Published by Elsevier B.V.
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| 3. |
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| 4. |
- Waara, Sylvia, 1958-, et al.
(författare)
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Distribution and removal efficiency of heavy metals in two constructed wetlands treating landfill leachate
- 2011
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Ingår i: Water Science and Technology. - London : IWA Publishing. - 0273-1223 .- 1996-9732. ; 64:8, s. 1597-1606
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Tidskriftsartikel (refereegranskat)abstract
- The results of heavy metals (Fe, Mn, Zn, Ni, Cu, Cr, Pb, Cd) removal and partitioning between aqueous and solid phases at two treatment wetlands (TWs) treating municipal landfill leachates are presented. One of the TWs is a surface flow facility consisting of 10 ponds. The other TW is a newly constructed pilot-scale facility consisting of three beds with alternately vertical and horizontal sub-surface flow. The metals concentrations were analysed in leachate (both TWs) and bottom sediments (surface flow TW). Very high (90.9-99.9%) removal rates of metals were observed in a mature surface flow TW. The effectiveness of metals removal in a newly constructed pilot-scale sub-surface flow wetland were considerably lower (range 0-73%). This is attributed to young age of the TW, different hydraulic conditions (sub-surface flow system with much shorter retention time, unoxic conditions) and presence of metallic complexes with refractory organic matter
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| 5. |
- Waara, Sylvia, 1958-
(författare)
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Landfill Leachate Ecotoxicity
- 2013
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Ingår i: Encyclopedia of Aquatic Ecotoxicology. - Dordrecht : Springer. - 9789400750401 ; , s. 649-670
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Bokkapitel (refereegranskat)
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| 6. |
- Waara, Sylvia, 1958-, et al.
(författare)
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Metal and Metalloid Sequestration in a Constructed Wetland System for Treatment of Landfill Leachate During 2003–2012
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The treatment of landfill leachate in constructed wetland systems is a common practice in Europe. However, very few studies were made to evaluate their performance over a long period of time. A free surface constructed wetland system consisting of sediment traps followed by 10 ponds connected with overflows was built at Atleverket near Örebro, Sweden in 2001. It receives pre-treated leachate from the municipal landfill. As part of the wetland monitoring programme a large data set on the surface concentrations of 15 metals and 2 metalloids has been collected from different sampling sites within the wetland during the operation period. In this study, the data from inlet and outlet of the wetland were compiled and analysed. The aim of this paper is therefore to estimate the removal efficiency of metals and metalloids using data on concentrations and flow and investigate the effect of wetland age on removal pattern. The elements with the highest removal efficiency were Al, As, Ba, Ca, Cr, Cu, Fe, Mn, Pb, V and Zn ranging from 95% for Pb to 65 % for Ca. The elements with the lowest reduction were B, Co K, Mg, Ni and S ranging from Co 56 % to 40 % for S. It was found that the removal efficiency was not related to inlet concentrations of the elements as the elements with high and low inlet concentrations were found in both groups. Analysis of reduction pattern also revealed that the group with higher removal efficiency showed fairly constant outlet concentrations during the study period, while the elements with lower removal efficiency demonstrated variable outlet concentrations. No statistical difference in removal due to age of the wetland was found. The study results showed that the wetland system has high removal efficiency of metals and metalloids and the removal pattern is not affected by age of the wetland. The influence on reduction due to leachate characteristics, wetland design and retention time will be discussed.
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| 7. |
- Waara, Sylvia, 1958-, et al.
(författare)
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The effect of environmental conditions on the stability of heavy meltal-filter material complex as assessed by the leaching of adsorbed metal ions
- 2011
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 159, s. 146-1463
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Tidskriftsartikel (refereegranskat)abstract
- In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metalefilter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metalefilter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching.
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| 8. |
- Waara, Sylvia, 1958-, et al.
(författare)
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Towards Recommendations for Design of Wetlands for Post-Tertiary Treatment of Waste Water in the Baltic Sea Region – Gdańsk Case Study
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There are many challenges that need to be addressed if the far reaching objectives on high environmental status as required in the EU Water Framework Directive and the Marine Strategy Framework Directive will be met in the Baltic Sea Region within the next decade. For wastewater treatment plants (WWTP) this implies, in spite of the many improvements made during the last decade, development and introduction of new technology to further reduce eutrophying compounds, hazardous chemicals and pharmaceuticals. Constructed wetlands when properly designed and operated have been shown to be robust systems with low energy requirements that may not only reduce many types of pollutants but may also provide many additional ecosystem services beyond requirements generally imposed by authorities. For example, they may support and enhance biodiversity and be used to convert brownfield areas in urban landscapes to recreational areas. Reduced cost is possible if treated water is reused in industry or for irrigation. In a project, supported by the Swedish Institute, a group of scientists, a water company and water using industry has together with local authorities through workshops, field studies and literature studies worked on finding a general first recommendation on design and operation. In this paper we will present the scientific rational and legal constraints for the general design and operation of a wetland system for post-tertiary treatment of waste water from WWTPs using Gdańsk as an example. The proposal includes a first part, which mainly will be focusing on pollutant and pathogen removal using particle traps and a HSSF wetland on land owned by the WWTP and a second part consisting of a FWS wetland which, in addition to further polishing the water, will enhance biodiversity and provide recreational areas on derelict land owned by the city.
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