Remoção de nitrogênio e fósforo do esgoto sanitário em um sistema de alagados construídos utilizando o capim vetiver

Abstract

RESUMONo presente trabalho objetivou-se avaliar a eficiência do capim vetiver (Vetiveria zizanioides L. Nash) na remoção de nitrogênio e fósforo do esgoto sanitário, em um sistema de tratamento do tipo alagados construídos. A unidade experimental possuiu doze módulos de tratamento, cada um preenchido com camadas sobrepostas de substrato. Do fundo até a superfície foram utilizados: 0,15 m de brita # 3; 0,10 m de brita # 1; 0,20 m de areia lavada e 0,05 m de brita # 1. No interior dos módulos, o esgoto foi mantido a 0,05 m ou a 0,25 m abaixo da superfície do substrato, resultando em tempos de detenção hidráulica de 3,4 dias ou 1,9 dias, respectivamente. O afluente foi captado da entrada da lagoa facultativa de uma Estação de Tratamento de Esgotos e aplicado na superfície de cada módulo, de forma automatizada, em uma taxa de aplicação superficial de 51 L.m -2 .d -1 . O esgoto percolava verticalmente no sistema, em um fluxo sub-superficial descendente, até ser captado em uma tubulação de drenagem no inferior do módulo. Determinaram-se as concentrações de fósforo total e nitrogênio amoniacal do esgoto antes e após passar pelo tratamento. As taxas de evapotranspiração foram medidas e, a partir delas, calcularam-se as eficiências na remoção da carga contaminante. Os resultados foram submetidos aos testes F e de Tukey, a 5% de probabilidade. O tratamento com a presença da planta e nível de esgoto a 0,05 m da superfície apresentou eficiência mais elevada na remoção dos nutrientes, com 90,5% para fósforo total e 93,9% para nitrogênio amoniacal.Palavras-chave: fósforo total, nitrogênio amoniacal, zona de raízes. Removal of nitrogen and phosphorus from wastewater in a constructed wetland system using vetiver grass ABSTRACTThis study aimed to evaluate the Vetiver grass (Vetiveria zizanioides L. Nash) efficiency in removing nitrogen and phosphorus from the wastewater in a constructed wetlands treatment system. The experimental unit had twelve treatment modules, filled with layers of substrate. From the bottom to the surface, the following materials were placed: 0.15 m of gravel # 3; 0.10 m of gravel # 1; 0.20 m of washed sand and 0.05 m of gravel # 1. Inside the modules, the wastewater was maintained at 0.05 m or 0.25 m below the substrate surface, resulting in hydraulic retention times of 3.4 days and 1.9 days, respectively. The influent wastewater was captured in the entrance of a facultative pond, and it was applied to the surface of each treatment module, automatically, on a surface application rate of 51 L.m -2 .d -1 . The sewage percolated vertically in the system, in a sub-surface flow downward until it was UCKER, F. E.; ALMEIDA, R. A.; KEMERICH, P. D. C. Remoção de nitrogênio e fósforo do esgoto sanitário em um sistema de alagados construídos utilizando o capim vetiver. Ambi-Agua, Taubaté, v. 7, n. 3, p. 87-98, 2012. (http://dx.doi.org/10.4136/ambi-agua.925) 88 captured in a drain pipe at the bottom of the module. The wastewater concentrations of total phosphorus and ammonium were analyzed before and after passing th...

Removal of nitrogen and phosphorus from cattle farming wastewater using constructed wetland system

“…In the samplings with the best results, it was observed that the treatment using horizontal subsurface-flow CWS was able to remove 76.5, 50.5, 37.4 and 64.4% of TKN, ammonia, nitrate and nitrite, respectively. These results are similar to those observed by many authors (Ucker et al, 2012;Matos et al, 2010;Tanner et al, 2005). It is important to point out that no chemical treatment was performed in the present study, only biological treatment for the removal of pollutants.…”

“…Matos et al (2010), using constructed wetland systems in the treatment of swine farming wastewater (PFW), obtained total N removal efficiency of 64% in systems cultivated with Tifton 85, and 61% for systems cultivated with Alternanthera. Ucker et al (2012) obtained good efficiency in the removal of ammonia in CWSs cultivated with vetiver.…”

“…A higher efficiency of removal of N compounds by the CWS cultivated with vetiver grass, which has rapid and high capacity to remove nutrients such as N and P, besides large amounts of agrochemicals and heavy metals was expected (Ucker et al, 2012). Cheng et al (2008) evaluated the performance of constructed wetland systems for an effluent that is disposed in one of the most polluted rivers of Taiwan, the Wu-Luo River, and obtained results of N removal from the effluent of about 93%.…”

“…Constructed wetland systems have limited capacity for P removal, because there is no permanent loss of the nutrient in these systems, which occurs, for example, in the removal of N compounds (Ucker et al, 2012).…”

“…Therefore, the species Vetiveria zizanioides, known as vetiver grass, very resistant to climatic variations and tolerant to contaminants (Ucker et al, 2012), is used in Brazil as vegetation on slopes, with the objective of controlling erosive processes (Andrade et al, 2011). The vetiver grass, since it has a deep and abundant root system, can be an alternative in constructed wetland systems (Barbosa and Lima, 2013).…”