Role of Plants in a Constructed Wetland: Current and New Perspectives

Abstract

Abstract:The role of plants in the treatment of effluents by constructed wetland (CW) systems is under debate. Here, we review ways in which plants can affect CW processes and suggest two novel functions for plants in CWs. The first is salt phytoremediation by halophytes. We have strong evidence that halophytic plants can reduce wastewater salinity by accumulating salts in their tissues. Our studies have shown that Bassia indica, a halophytic annual, is capable of salt phytoremediation, accumulating sodium to up to 10% of its dry weight. The second novel use of plants in CWs is as phytoindicators of water quality. We demonstrate that accumulation of H 2 O 2 , a marker for plant stress, is reduced in the in successive treatment stages, where water quality is improved. It is recommended that monitoring and management of CWs consider the potential of plants as phytoremediators and phytoindicators.

Efeito da vegetação em sistemas alagados construídos para tratar águas residuárias da suinocultura

“…No SAC 2 foi plantada a taboa (Typha latifolia), e no SAC 3 , o capim tifton-85 (Cynodon spp.). Quanto à remoção de demanda bioquímica de oxigênio (DBO) e de sólidos suspensos totais (SST), não se constatou diferença entre os SACs (p>0, 05), no entanto a eficiência de remoção de demanda química de oxigênio (DQO) foi diferente entre os SACs orgânica, mineralização de nutrientes e remoção de patógenos, bem como funcionam como intermediárias em processos físicos e químicos como filtração, adsorção, precipitação e sedimentação (BRIX, 1994;1997;BIAŁOWIEC;JANCZUKOWICZ;RANDERSON, 2011;SHELEF;GROSS;RACHMILEVITCH, 2013). Apesar de controvérsias, autores como Hua et al (2014) e Matos et al (2015), entre outros, têm demonstrado que a planta e seu sistema radicular também contribuem para o aumento do tempo de vida útil das unidades, pela atenuação do progressivo processo de obstrução do meio poroso.…”

“…Isso leva ao questionamento do papel das macrófitas nesses sistemas (BRIX, 1997;MARA, 2004;SHELEF;GROSS;RACHMILEVITCH, 2013), não havendo consenso entre pesquisadores a respeito da efetiva importância das macrófitas aquáticas nos SACs. No entanto novos trabalhos, notadamente aqueles que consideram as perdas de água por evapotranspiração no sistema, têm evidenciado essa importância (BIAŁOWIEC; JANCZUKOWICZ; RANDUSON, 2011;MESQUITA et al, 2013).…”

A Constructed Wetland System for Rural Household Sewage Treatment in Subtropical Regions

“…from decomposition of organic pollutants can be removed by plant uptake. Therefore, as an essential component, wetland plants play an important role in both the constitution of a wetland system and enhancement of its treatment efficiency [12,14]. However, the amounts of nitrogen and phosphorus removed directly by plant uptake are relatively low, which, according to Dzakpasu et al [29], contributes less than 16% of the total removal rates.…”

“…In order to obtain a better understanding of pollutant removal mechanisms, studies have been carried out by different workers on factors that determine the treatment efficiency of constructed wetland systems, including wetland types and combinations [5,10]; hydraulic and pollutant loads [2,11]; plant species [12][13][14]; substrates [15,16]; and their interactions [17,18], etc. The increasing trend in CW technology application coupled with stricter water quality standards requires development of better process design tools.…”

Evaluation of Phytodesalination Potential of Vegetated Bioreactors Treating Greenhouse Effluent

“…However, available publications on the assessment of the salt-accumulating plants, specifically focused on application in water desalination are scarce. In the limited studies available, the use of halophytic species in CWs was reported as a novel strategy to reduce salinity by Na + uptake [11]. In addition, several halophytic species have demonstrated the capability of accumulating Na + and Cl − in their tissue when the species were exposed to the simulated greenhouse effluent [12].…”