Desempenho de sistemas alagados construídos no tratamento de águas residuárias da lavagem e descascamento/despolpa dos frutos do cafeeiro
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Data
2008
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Universidade Federal de Viçosa
Resumo
Em vista da escassez de informações técnicas específicas sobre o tratamento de águas residuárias da lavagem e descascamento/despolpa dos frutos do cafeeiro (ARC) utilizando sistemas alagados construídos de escoamento subsuperficial (SACESF), este trabalho teve como objetivos estudar o desempenho de SACESFs, cultivados com taboa (Typha sp.) e alternantera (Alternanthera philoxeroides), no tratamento da ARC. Estes sistemas foram submetidos a diferentes condições experimentais e à aplicação de diferentes cargas orgânicas. Além disso, objetivou-se avaliar o desempenho agronômico e a extração de nutrientes pelas plantas nas diferentes condições de operação do sistema. Para realização do estudo, foram montados na Área de Préprocessamento e Armazenamento de Produtos Agrícolas, do Departamento de Engenharia Agrícola da UFV nove SACESFs constituídos por caixas de madeira de pínus, impermeabilizadas internamente com geomembrana de PEAD, com 0,5 mm de espessura, nas dimensões de 0,4 m de altura x 0,5 m de largura x 1,5 m de comprimento, e declividade de 0,01 m m-1. Como meio suporte, utilizou-se brita "zero" até a altura de 0,35 m, mantendo-se o nível d’água a 0,05 m abaixo da superfície do material suporte. Em cada SACESF, implementou-se, nos primeiros 0,75 m, a espécie alternantera e, nos últimos 0,75 m, a taboa. Após dois meses de implantação do sistema, iniciou-se a aplicação da ARC, sendo o experimento conduzido em três fases. Na fase I, três sistemas receberam ARC diluída, três receberam ARC diluída e com correção de pH (elevação do pH até próximo de 7,0) e, nos três últimos SACESFs, aplicou-se os efluentes de filtros anaeróbios, os quais foram alimentados com ARC diluída e correção de pH. Na fase II, aumentou-se a carga orgânica aplicada e manteve um tempo de residência hidráulico (TRH) médio de 59 horas, sendo o sistema conduzido por três vias: 1 - A ARC foi lançada diretamente nos SACESFs, em três concentrações diferentes: 50% v/v; 75% v/v e 100%, sendo os três SACESFs denominados SAC1, SAC2 e SAC3, respectivamente; 2 - A ARC recebeu correção com cal hidratada até pH aproximadamente 7 e correção nutricional (DBO/N/P = 100/5/1) e foi lançada em três concentrações: 50% v/v, 75% v/v e 100%, sendo os três SACESFs denominados SAC*1, SAC*2 e SAC*3, respectivamente; 3 - A ARC recebeu correção com cal hidratada até pH aproximadamente 7 e correção nutricional (DBO/N/P = 100/5/1) e foi aplicada em filtros anaeróbios, em três concentrações: 50% v/v; 75% v/v e 100%; sendo os efluentes, posteriormente, lançados nos SACESFs, respectivamente denominados SACF1; SACF2 e SACF3, como pós-tratamento. Na fase III, procedeu-se da mesma forma que na fase II, com exceção do TRH médio que foi aumentado para 109 horas. Com a condução do experimento verificou-se que o aumento nas taxas de carga superficial dos constituintes no sistema, proporcionou decréscimo na eficiência de remoção destes em todos os SACESFs avaliados, além disso, para a maioria das variáveis avaliadas, as concentrações destas nos efluentes acompanharam a instabilidade da carga orgânica afluente, indicando a sensibilidade do sistema às variações de carga aplicada. Quando se aumentou o TRH médio para valores acima de 100 horas (fase III), os SACESFs apresentaram maiores eficiências na remoção de DQO (SAC*1, SACF1 e SACF2) e DBO (SAC1, SAC*1, SACF2 e SACF3) que os tempos de residência hidráulica de, aproximadamente, 60 horas aplicado nas fases I e II do experimento. Esta maior eficiência foi favorecida pelas menores cargas orgânicas aplicadas (sub-índice 1), pela correção nutricional e do pH (*) e pelo tratamento nos filtros anaeróbios (F). Entretanto, nem mesmo o tempo de residência hidráulica de 100 horas foi suficiente para produzir um efluente que atendesse aos padrões de lançamento em corpos hídricos receptores, em conformidade com a legislação ambiental do estado de Minas Gerais. As plantas cultivadas não se adaptaram às condições de exposição às altas cargas orgânicas, não apresentando bom desempenho agronômico, em termos de produtividade e extração de nutrientes, exceto as cultivadas no SACF1. Entre as duas espécies avaliadas, a alternantera foi a espécie vegetal que apresentou maior capacidade extratora de nutrientes, chegando a extrair, aproximadamente, 4,6; 28,8 e 9,1% de todo o N, P e K aplicados no SACF1. Comparando-se os nove SACESFs, verifica-se que o SACF1, que recebeu a menor carga orgânica (1.500 kg ha-1 d-1 de DQO) na terceira fase, foi aquele que apresentou melhor desempenho, no que se refere à remoção de matéria orgânica e compostos fenólicos dos efluentes dos filtros anaeróbios utilizados no tratamento da ARC. As eficiências médias de remoção de DBO, DQO e compostos fenólicos desse sistema foram iguais a 63, 85 e 65%, respectivamente.
Taking into account the shortage of specific technical information about the treatment of the wastewaters from the washing/husking the fruits of the coffee shrub (ARC), by using the constructed wetland systems of the subsuperficial flowing type (SACESF), this study was conducted to evaluate the performance of SACESFs cropped with cattail (Typha sp.) and alligatorweed (Alternanthera philoxeroides) in the ARC treatment. Those systems were subjected to either different experimental conditions and the application of different organic loads. It was also aimed to evaluate the agronomic performance and nutrient extraction by the plants under different operational conditions of the system. So, nine SACESFs constituted by pinus wood-made boxes internally waterproof with PEAD geomembrane with 0.5 mm thickness, measuring 0.4 m height x 0.5 m width x 1.5 m length and 0.01 m m-1 slope. As a supporting medium, the crushed stone "zero" was used up to 0.35 m height, whereas maintaining the water level at 0.05 m below the surface of the supportable material. In each SACESF, the A. philoxeroides species was implemented at the first 0.75 m and the Typha sp. at the last 0.75 m. After two months from implantation of the system, the ARC application was begun, as being the experiment conducted at three phases. In phase I, three systems received diluted ARC, three received diluted ARC with pH correction (pH increased up to 7.0 approximately), and whereas the last three SACESFs were applied the effluents of the anaerobic filters that were fed diluted ARC with pH correction. At phase II, the applied organic load was increased and an average hydraulic residence time (HRT) was maintained at 59 hours, as being the system conducted by three vias as follows. 1 - The ARC was directly thrown into SACESFs, at three different concentrations: 50% v/v; 75% v/v and 100%, which were so-called SAC1, SAC2 and SAC3, respectively; 2 - the ARC was given correction with hydrated lime until pH around 7 and nutritional correction (BOD/N/P = 100/5/1), and it was thrown at three concentrations: 50% v/v, 75% v/v and 100%, as being those three SACESFs so-called SAC*1, SAC*2 and SAC*3, respectively; 3 - the ARC was given either correction with hydrated lime until reaching the pH around 7 and the nutritional correction (BOD/N/P = 100/5/1). Then, it was applied at three concentrations (50% v/v; 75% v/v and 100%) in anaerobic filters; later, the effluents were thrown into SACESFs socalled SACF1; SACF2 and SACF3 respectively for post-treatment. The same procedure followed at phase II was adopted for phase III, except the average HRT that was increased to 109 hours. During the experiment, it was verified that the increased surface load rates of those constituents of the system provided decrease in their removal efficiency in all SACESFs. In addition, for most variables under evaluation, the concentrations of those rates in the effluents followed the instability of the affluent organic load, therefore indicating the sensibility of the system to the variations in the load applied. When the average HRT was increased to values above 100 hours (phase III), the SACESFs showed higher efficiencies in the removal of COD (SAC*1, SACF1 and SACF2) and BOD (SAC1, SAC*1, SACF2 and SACF3) than the hydraulic residence times around 60 hours applied at the experimental phases I and II. This higher efficiency was favored by the lowest organic loads applied (subindex 1), by the nutritional correction and pH (*) and by the treatment in the anaerobic filters (F). However, even the hydraulic residence time of 100 hours was not enough to producing an effluent that would satisfy the patterns for release into receiving water bodies, in accordance with the environmental legislation by State of Minas Gerais. The cropped plants showed no adaptation to exposure to the high organic loads, since they did not present a satisfactory agronomic performance, relative to productivity and nutrient extractions, except those cropped in SACF1. Among the species under evaluation, the A. philoxeroides was the one showing higher capacity for extracting the nutrients, as it reached an extraction around 4.6; 28.8 and 9.1 % of the whole N, P and K applied in SACF1. When comparing those nine SACESFs, one may verify the SACF1 that received the lowest organic load (1,500 kg ha-1 d-1 COD) presented the best performance concerning to the removal of the organic matter and phenolic compounds from the effluents of the anaerobic filters used in the ARC treatment. The average removal efficiencies of BOD, COD and phenolic compounds of this system were 63±22, 85±9 and 65±11%, respectively.
Taking into account the shortage of specific technical information about the treatment of the wastewaters from the washing/husking the fruits of the coffee shrub (ARC), by using the constructed wetland systems of the subsuperficial flowing type (SACESF), this study was conducted to evaluate the performance of SACESFs cropped with cattail (Typha sp.) and alligatorweed (Alternanthera philoxeroides) in the ARC treatment. Those systems were subjected to either different experimental conditions and the application of different organic loads. It was also aimed to evaluate the agronomic performance and nutrient extraction by the plants under different operational conditions of the system. So, nine SACESFs constituted by pinus wood-made boxes internally waterproof with PEAD geomembrane with 0.5 mm thickness, measuring 0.4 m height x 0.5 m width x 1.5 m length and 0.01 m m-1 slope. As a supporting medium, the crushed stone "zero" was used up to 0.35 m height, whereas maintaining the water level at 0.05 m below the surface of the supportable material. In each SACESF, the A. philoxeroides species was implemented at the first 0.75 m and the Typha sp. at the last 0.75 m. After two months from implantation of the system, the ARC application was begun, as being the experiment conducted at three phases. In phase I, three systems received diluted ARC, three received diluted ARC with pH correction (pH increased up to 7.0 approximately), and whereas the last three SACESFs were applied the effluents of the anaerobic filters that were fed diluted ARC with pH correction. At phase II, the applied organic load was increased and an average hydraulic residence time (HRT) was maintained at 59 hours, as being the system conducted by three vias as follows. 1 - The ARC was directly thrown into SACESFs, at three different concentrations: 50% v/v; 75% v/v and 100%, which were so-called SAC1, SAC2 and SAC3, respectively; 2 - the ARC was given correction with hydrated lime until pH around 7 and nutritional correction (BOD/N/P = 100/5/1), and it was thrown at three concentrations: 50% v/v, 75% v/v and 100%, as being those three SACESFs so-called SAC*1, SAC*2 and SAC*3, respectively; 3 - the ARC was given either correction with hydrated lime until reaching the pH around 7 and the nutritional correction (BOD/N/P = 100/5/1). Then, it was applied at three concentrations (50% v/v; 75% v/v and 100%) in anaerobic filters; later, the effluents were thrown into SACESFs socalled SACF1; SACF2 and SACF3 respectively for post-treatment. The same procedure followed at phase II was adopted for phase III, except the average HRT that was increased to 109 hours. During the experiment, it was verified that the increased surface load rates of those constituents of the system provided decrease in their removal efficiency in all SACESFs. In addition, for most variables under evaluation, the concentrations of those rates in the effluents followed the instability of the affluent organic load, therefore indicating the sensibility of the system to the variations in the load applied. When the average HRT was increased to values above 100 hours (phase III), the SACESFs showed higher efficiencies in the removal of COD (SAC*1, SACF1 and SACF2) and BOD (SAC1, SAC*1, SACF2 and SACF3) than the hydraulic residence times around 60 hours applied at the experimental phases I and II. This higher efficiency was favored by the lowest organic loads applied (subindex 1), by the nutritional correction and pH (*) and by the treatment in the anaerobic filters (F). However, even the hydraulic residence time of 100 hours was not enough to producing an effluent that would satisfy the patterns for release into receiving water bodies, in accordance with the environmental legislation by State of Minas Gerais. The cropped plants showed no adaptation to exposure to the high organic loads, since they did not present a satisfactory agronomic performance, relative to productivity and nutrient extractions, except those cropped in SACF1. Among the species under evaluation, the A. philoxeroides was the one showing higher capacity for extracting the nutrients, as it reached an extraction around 4.6; 28.8 and 9.1 % of the whole N, P and K applied in SACF1. When comparing those nine SACESFs, one may verify the SACF1 that received the lowest organic load (1,500 kg ha-1 d-1 COD) presented the best performance concerning to the removal of the organic matter and phenolic compounds from the effluents of the anaerobic filters used in the ARC treatment. The average removal efficiencies of BOD, COD and phenolic compounds of this system were 63±22, 85±9 and 65±11%, respectively.
Descrição
Tese de Doutorado defendida na Universidade Federal de Viçosa
Palavras-chave
Café; Águas residuais; Plantas aquáticas; Reatores biológicos;, Coffee; Wastewaters; Aquatic plants; Biological reactors;
Citação
Fia, Ronaldo. Desempenho de sistemas alagados construídos no tratamento de águas residuárias da lavagem e descascamento/despolpa dos frutos do cafeeiro. Viçosa : UFV, 2008. 181f. : il. (Tese - Doutorado em Engenharia Agrícola) - Universidade Federal de Viçosa. Orientador: Antonio Teixeira de Matos. T 628.162 F438d 2008