ABSTRACT
The present work aimed to evaluate the removal efficiency of the endocrine disruptors ethinyl estradiol (EE2), the progestin levonorgestrel (LNG), and bisphenol A (BPA), considered to be contaminants of major concern, by using four laboratory scale constructed wetlands (CW) - three containing gravel as support media, one cultivated with Cyperus isocladus (WL1), other with Eichhornia crassipes (WL3), and one without macrophyte (WL2). The fourth unit contained gravel and bamboo charcoal as support medium, also cultivated with Cyperus isocladus (WLC). Two hydraulic retention times (HRT) were tested, 2 and 4â¯days. Average removals ranged from 9.0 to 95.6% for EE2, from 29.5 to 91.2% for BPA and from 39.1 to 100.0% for LNG. The results showed that the most efficient CW for removal of EE2 and BPA was WLC, and for LNG removal was WL3. The 2 days HRT was statistically more efficient in removing EE2, and the 4 days HRT was more efficient in the LNG removal. The other endocrine disruptors and concentration ranges were not influenced by HRT. It was concluded that WLC was the most suitable CW for removal of these three compounds, and it possibly is efficient also for the removal of other endocrine disruptors with similar physical-chemical characteristics.
Subject(s)
Benzhydryl Compounds/metabolism , Ethinyl Estradiol/metabolism , Levonorgestrel/metabolism , Phenols/metabolism , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/analysis , Wetlands , Cyperus/metabolism , Eichhornia/metabolism , Endocrine Disruptors/metabolismABSTRACT
RESUMO O descarte incorreto de resíduos, mesmo após tratamento, pode causar impactos negativos nos corpos d'água receptores. Em especial, substâncias como nitrogênio e fósforo podem se tornar, em função de suas concentrações, tóxicas para os organismos aquáticos ou produzir condições favoráveis à proliferação de vegetação, que podem iniciar os processos de eutrofização. Leitos cultivados são sistemas de tratamento de esgoto construídos com a finalidade de imitar a estrutura das wetlands naturais, promovendo mecanismos de fitorremediação. Apesar de a Eichhornia crassipes ser uma planta invasiva causadora de problemas em rios e lagos eutrofizados, seu uso pode ser interessante em leitos cultivados, pois é uma planta ornamental, o que aumentará a aceitação do sistema de tratamento de águas residuárias, além de poder ser reutilizada no artesanato, na produção de biocombustível e na alimentação animal. Nesse contexto, o presente trabalho objetivou avaliar a eficiência de retenção/remoção de fósforo total e nitrogênio total Kjeldahl (NTK) presentes em águas residuárias a partir de dois leitos de fluxo subsuperficial horizontal cultivados com Eichhornia crassipes, com diferença de 43 dias de cultivo entre eles, fixados a um meio suporte. As concentrações de fósforo total variaram de 4,5 a 5,1 mg.L-1 no afluente e de 3,2 a 4,4 mg.L-1 no efluente dos leitos cultivados, enquanto as concentrações de NTK variaram de 95,9 a 104,7 mg.L-1 no afluente e de 77,5 a 85,3 mg.L-1 no efluente.
ABSTRACT Improper disposal, even after treatment, of wastewater can cause negative impacts on receiving water bodies. Particularly, substances such as nitrogen and phosphorus can become, depending on their concentrations, toxic to aquatic organisms or produce favorable conditions for the proliferation of a vegetation that can start the process of eutrophication. Constructed wetlands are a wastewater treatment built to mimic the structure of natural wetlands, promoting mechanisms of phytoremediation. Despite E. crassipes be an invasive plant which causes problems in eutrophic lakes and rivers, its use may be interesting in wetlands because it is an ornamental plant, which will increase wastewater treatment system's acceptance, and it can be reused in crafts, in biofuel production and in animal feed. In this context, the present study aimed to evaluate the efficiency of the retention/removal of total phosphorus and Kjeldahl nitrogen (TKN) present in wastewater by two subsurface horizontal flow constructed wetland system cultivated with Eichhornia crassipes, with a difference of 43 days of cultivation, fixed to a support medium. The concentrations of total phosphorus ranged from 4.5 to 5.1 mg.L-1 in the affluent and from 3.2 to 4.4 mg.L-1 in the effluent of constructed wetlands, whereas NTK concentrations ranged from 95.9 to 104.7 mg.L-1 in the effluent, and from 77.5 to 85.3 mg.L-1 in the effluent.
