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  • Küçük Resim
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    Constructed wetlands for boron removal: A review
    (2014) Türker, Onur Can; Vymazal, Jan; Türe, Cengiz
    Boron (B) contamination in the environment still increases because of various natural sources and anthropogenic activities. Therefore, the problem of removing B from water becomes a worldwide concern due to its toxicity and chronic effects on plants, animals and human health. This situation has generated increasing interest in the use of several wastewater treatment technologies in order to remove B from contaminated water. Constructed wetlands (CWs) present friendly alternative methods to treat wastewater around the world, and are used for removing various contaminants including metals and metalloids. This paper reviews current knowledge regarding the removal process of B, discusses application of B removal, and identifies critical knowledge study fields of future and gaps. Despite the fact that the sediment is a major sink for the removal of B, plants can play a significant role under favorable environmental conditions. The most important environmental factors that affect B removal in CWs are climatic conditions (e.g. transpiration rates), pH, temperature, solutions composition and competing species, hydraulic retention time and supporting media. Further research is needed on the major removal mechanism of B in CWs, namely the applicability of surface flow system, hybrid systems and vertical flow systems to remove B from wastewaters, the role of microorganism in order to enhance B removal efficiency. © 2014 Elsevier B.V.
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    Öğe
    Heavy metals in wetlands in Turkey
    (Springer Science and Business Media B.V., 2021) Türker, Onur Can; Vymazal, Jan
    Wetland areas are one of the most precious ecosystem because they contain rare ecological assets. The total area of wetlands of Turkey is 9.861 km2 and wetlands cover 1.2% of total area of Turkey. Unfortunately, most wetland areas of Turkey face great challenges due to various pollution factors including heavy metals pollution caused by rapid industrialization and urbanization. In this chapter, current heavy metal pollution status of wetland areas, especially Ramsar Sites in Turkey, was assessed by more than 60 articles dealing with concentrations of heavy metals in sediment, water, and aquatic organisms. The results from the literature demonstrated that anthropogenic activities were closely related to heavy metal pollution causing a significant threat to wetlands including some Ramsar sites. In this respect, Ramsar areas of Lake Uluabat and Gediz Delta were severely contaminated by heavy metals. Moreover, heavy metal pollution in other Ramsar sites such as Kızılırmak Delta, Sultan Marshes, Lake Manyas, Lake Burdur, and Seyfe Lake had moderate levels. Low potential heavy metal pollution risk was reported for a Ramsar site of Akyatan Lagoon. On the other hand, high levels of heavy metals were found in various wetland areas of Turkey, and heavy metal concentrations in water of Lake Hazar, Yeniçağa Lake, Terkos Lake, and Beyşehir Lake were higher than the permissible levels for drinking water suggested by WHO (World Health Organization). Plankton, zoobenthos, and fishes which lives in polluted wetland habitats had also higher concentrations of heavy metals in their tissues, and thus heavy metal pollution can pose a potential risk for food chain both in wetland and terrestrial ecosystems of Turkey.
  • Küçük Resim
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    Impacts of various filtration media on wastewater treatment and bioelectric production in up-flow constructed wetland combined with microbial fuel cell (UCW-MFC)
    (Elsevier, 2018) Yakar, Anıl; Türe, Cengiz; Türker, Onur Can; Vymazal, Jan; Saz, Çağdaş
    A successful design and operation of up-flow constructed wetlands combined with microbial fuel cell (UCW-MFC) were assessed for wastewater treatment and bioelectric production. One of the main aims of present study is also to investigate effect of various types of filtration media on wastewater treatment process and bioelectric production in UCW-MFC systems, and determine the most efficient media type in order to obtain higher wastewater treatment performance and generate higher bioelectric production. In the present experiment, UCW-MFC system with zeolite (clinoptilolite) as filtration media had higher treatment efficiency compared to other UCW-MFC systems with sand and volcanic cinder, and average COD, NH4+, NO3-, and TP removal efficiency were 92.1%, 93.2%, 81.1%, and 96.7%, respectively. This superior performance in the zeolite medium in the UCW-MFC system was due to its larger specific surface area, different framework structure, and more porous composition. On the other hand, the maximum average output voltage, power density, and Coulombic efficiency were also obtained for zeolite wetland system which 1.008 +/- 0.14 V, 15.1 mWatt/m(2), and 1.64%, respectively. In this respect, we found that the formation of electrogenic bacteria-zeolite media-graphite surface facilitate the degradation of organic substrate and increase electrogenic bacteria' activities which are catalyzed during the electron flow from anode to the cathode. Thus, the results suggest that zeolite-based filtration media can be use for improving the treatment efficiency and bioelectric production in UCW-MFC.