Constructed Wetlands: A Review on the Role of Radial Oxygen Loss in the Rhizosphere by Macrophytes

Wang, Qian; Hu, Ying; Xie, Huijun; Yang, Zhongchen

doi:10.3390/w10060678

Cited by 70 publications

(35 citation statements)

References 56 publications

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“…The plants that grow in constructed wetlands have several properties related to the water treatment process that make them an essential component of the design. Macrophytes are the main source of oxygen in CWs through a process that occurs in the root zone, called radial oxygen loss (ROL) [17]. The ROL contributes to the removal of pollutants because it favors an aerobic micro-environment, and waste removal is therefore accelerated, whereas, in anaerobic conditions (the main environment in CWs), there is less pollutant removal.…”

Section: Role Of Macrophytes In Cwsmentioning

confidence: 99%

Role of Wetland Plants and Use of Ornamental Flowering Plants in Constructed Wetlands for Wastewater Treatment: A Review

et al. 2019

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The vegetation in constructed wetlands (CWs) plays an important role in wastewater treatment. Popularly, the common emergent plants in CWs have been vegetation of natural wetlands. However, there are ornamental flowering plants that have some physiological characteristics similar to the plants of natural wetlands that can stimulate the removal of pollutants in wastewater treatments; such importance in CWs is described here. A literature survey of 87 CWs from 21 countries showed that the four most commonly used flowering ornamental vegetation genera were Canna, Iris, Heliconia and Zantedeschia. In terms of geographical location, Canna spp. is commonly found in Asia, Zantedeschia spp. is frequent in Mexico (a country in North America), Iris is most commonly used in Asia, Europe and North America, and species of the Heliconia genus are commonly used in Asia and parts of the Americas (Mexico, Central and South America). This review also compares the use of ornamental plants versus natural wetland plants and systems without plants for removing pollutants (organic matter, nitrogen, nitrogen and phosphorous compounds). The removal efficiency was similar between flowering ornamental and natural wetland plants. However, pollutant removal was better when using ornamental plants than in unplanted CWs. The use of ornamental flowering plants in CWs is an excellent option, and efforts should be made to increase the adoption of these system types and use them in domiciliary, rural and urban areas.

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Section: Role Of Macrophytes In Cwsmentioning

confidence: 99%

Role of Wetland Plants and Use of Ornamental Flowering Plants in Constructed Wetlands for Wastewater Treatment: A Review

et al. 2019

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“…For that, they integrate several components, including the treatment basin, substrate, selected plant species, and a panoply of associated organisms [13,14]. Although there are reports on the microbial dynamics and their association to macrophytes, these studies are mainly focused on bacteria [15][16][17], underestimating other important microbial organisms, such as fungi. Both bacteria and fungi have important roles in the assimilation, transformation, and recycling of chemical constituents present in various wastewaters.…”

Section: Introductionmentioning

confidence: 99%

Diverse Arbuscular Mycorrhizal Fungi (AMF) Communities Colonize Plants Inhabiting a Constructed Wetland for Wastewater Treatment

Calheiros

Pereira

Franco

et al. 2019

Water

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Constructed wetlands (CWs) are biological wastewater treatment systems that comprise several components where plants and associated organisms play an important role in water depuration. Microbial studies emphasize bacterial dynamics, whereas studies of arbuscular mycorrhizal fungi (AMF) are scarce and the functional role of AMF in aquatic and wetland plants is poorly understood. The aim of this study was to analyze the AMF communities colonizing the roots of Canna indica, Canna flaccida, and Watsonia borbonica inhabiting a CW treating wastewater of a tourism unit. The dynamics of the AMF communities were evaluated by Denaturing Gradient Gel Electrophoresis (DGGE) of 18S rRNA gene amplification products along cold (C) and hot (H) seasons for three consecutive years. DGGE profiles allowed the estimation of AMF species richness (S), and Shannon-Wienner (H) and Pielou (J) indexes, for the different plant species, showing differences between species and along the years. Excised bands from DGGE were analyzed and identified through sequencing for arbuscular mycorrhiza, revealing the presence of AMF strains closely related to Glomus sp., Rhizophagus sp. and Acaulospora sp. genera. Concomitant water quality analyses showed that the system was effective in organic and nutrient removal during the sampling period. Findings from this study suggest that AMF diversity found in the CW is influenced by the water constituents, season, and plant species.

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“…Mesocosms with different vegetation and substrate showed no significant difference (p = 0.234). This indicated that the presence of vegetation favored the release of radial oxygen [27], and this allowed nitrification in the rhizosphere zone. After denitrification processes in the anaerobic area, this last process could only have been present in the mesocosms with no plants, and in minor proportions, since the presence of vegetation under anaerobic conditions also favors carbon exudation from the root, which intensifies the denitrification [28].…”

Section: Concentration and Removal Of Contaminants In Cw Mesocosmsmentioning

confidence: 94%

Impact of Ornamental Vegetation Type and Different Substrate Layers on Pollutant Removal in Constructed Wetland Mesocosms Treating Rural Community Wastewater

et al. 2019

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Improving water quality is a relevant environmental aspect, and using constructed wetlands (CWs) is a sustainable option for this; both porous material filled cells and plants that collectively remove contaminants must be readily available and inexpensive. This study evaluated CWs and their functionality by comparing two ornamental plants (Spathiphyllum wallisii and Hedychium coronarium) planted in experimental mesocosm units filled with layers of porous river rock, tepezil, and soil, or in mesocosms with layers of porous river rock, and tepezil, without the presence of soil. The findings during the experiments (180 days), showed that the removal of pollutants (chemical oxygen demand (COD), total solids suspended (TSS), nitrogen as ammonium (N-NH 4 ), as nitrate (N-NO 3 ), and phosphate (P-PO 4 ) was 20-50% higher in mesocosms with vegetation that in the absence of this, and those mesocosms with the soil layer between 33-45% favored removal of P-PO 4 . Differences regarding of vegetation removal were only observed for N-NH 4 , being 25-45% higher in CWs with H. coronarium, compared with S. wallisii. Both species are suitable for using in CWs, for its functionality as phytoremediation, and aesthetic advantages could generate interest for wastewater treatment in rural communities, parks, schools or in domiciliary levels like floral flower boxes in the backyard. The study also revealed that a soil layer in CWs is necessary to increase the removal of P-PO 4 , an ion hardly eliminated in water treatment.

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Constructed Wetlands: A Review on the Role of Radial Oxygen Loss in the Rhizosphere by Macrophytes

Cited by 70 publications

References 56 publications

Role of Wetland Plants and Use of Ornamental Flowering Plants in Constructed Wetlands for Wastewater Treatment: A Review

Role of Wetland Plants and Use of Ornamental Flowering Plants in Constructed Wetlands for Wastewater Treatment: A Review

Diverse Arbuscular Mycorrhizal Fungi (AMF) Communities Colonize Plants Inhabiting a Constructed Wetland for Wastewater Treatment

Impact of Ornamental Vegetation Type and Different Substrate Layers on Pollutant Removal in Constructed Wetland Mesocosms Treating Rural Community Wastewater

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