Reúso de água residuária tratada no cultivo de hortaliças
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Data
2019-11-08
Autores
Santos, Roberta Daniela Da Silva [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As atividades humanas no geral são extremamente dependentes da água. Entretanto, a utilização deste indispensável recurso na geração de energia, abastecimento humano, lazer, indústria e na agricultura, quando realizada de maneira inadequada, pode comprometer sua qualidade. Assim, faz-se necessário incorporar na irrigação a prática do reúso, utilizando, por exemplo, água residuária tratada (ART). Desta forma, os objetivos deste trabalho foram: avaliar a viabilidade do uso de água residuária tratada por dois sistemas distintos, tanque séptico + SODIS + 125 mg L-1 H2O2 (ARTS) e alagados construídos (ARTAC), através da irrigação por gotejamento nas culturas alface, beterraba e rabanete, em termos de produção, contaminação por Escherichia coli, e eficiência do uso da água (EUA); calcular o percentual de macronutrientes fornecido pela ARTS e ARTAC; e verificar a uniformidade do sistema de irrigação operando com elas. As hortaliças foram cultivadas a campo com cinco composições da lâmina de irrigação 0, 25, 50, 75 e 100% de ARTS e ARTAC. Durante a condução do experimento foram realizadas análises físicas, química e microbiológicas na ART. Após a colheita foram realizadas análises biométricas, de produtividade e microbiológicas nas amostras de hortaliças, como também a uniformidade do sistema de irrigação. A irrigação com ARTS e ARTAC proporcionou melhor rendimento de todas as hortaliças se comparado ao plantio convencional (0% ART). Os dois sistemas avaliados e as quatro composições da lâmina de irrigação (com ART) possibilitaram produção das hortícolas isenta de contaminação com E. coli, classificando-as como apta ao consumo humano crua. Para as três culturas avaliadas irrigadas com ARTS e ARTAC, os valores de EUA foram superiores quando comparados ao sistema de plantio convencional (0% ART). No que diz respeito ao percentual de fertilizantes químicos proporcionado pelo uso de ARTS e ARTAC, com base na oferta e na recomendação nutricional para as culturas, considerando apenas os macronutrientes nitrogênio (N), fósforo (P) e potássio (K), a ARTS e ARTAC, conseguiram atender parcialmente as necessidades nutricionais da alface e da beterraba (N, P e K) e totalmente a do rabanete em relação ao N e parcialmente a de P e K. A partir dos coeficientes avaliados, verificou-se que a ARTS e ARTAC não comprometeram a uniformidade de aplicação de água, e comparando a avaliação do sistema de irrigação operando com ARTAC e ARTS, o desempenho foi melhor com ARTAC, devido à menor concentração de sólidos suspensos e de coliformes totais, consequentemente, menor susceptibilidade a obstrução dos emissores. Portanto, os dois sistemas são capazes de fornecer ART para irrigação por gotejamento de hortaliças, dentro dos padrões físico-químicos e microbiológicos estabelecidos na legislação, favorecendo o desenvolvimento das culturas, além de proporcionar uma fonte alternativa de nutrientes para as plantas e de água para irrigação.
Human activities in general are extremely dependent on water. However, the use of this indispensable resource in power generation, supply, industry and agriculture, when improperly performed, may compromise its quality. Thus, it is necessary to incorporate the practice of reuse in irrigation, using for example, treated wastewater (TW). Thus, the objectives of this work were: to evaluate the feasibility of using wastewater treated by two distinct systems, septic tank + SODIS + 125 mg L-1 H2O2 (TWST) and constructed wetlands (WTCW), through drip irrigation in lettuce, beet and radish crops in terms of yield, Escherichia coli contamination, and water use efficiency (WUE); calculate the percentage of macronutrients provided by TWST and WTCW; and verify the uniformity of the irrigation system operating with TWST and WTCW. The vegetables were field grown with five irrigation depth compositions 0, 25, 50, 75 and 100% TWST and WTCW. During the conduction of the experiment, physical, chemical and microbiological analyzes were performed at TW. After harvesting, biometric, yield and microbiological analyzes were performed on the vegetable samples, as well as the uniformity of the irrigation system. Irrigation with TWST and WTCW provided better yield of all vegetables compared to conventional planting (0% TW). Both evaluated systems and the four irrigation depth compositions (with TW) made it possible to produce vegetables free of E. coli contamination, classifying them as suitable for raw human consumption. For the three evaluated crops irrigated with TWST and WTCW, the WUE values were higher when compared to the conventional system (0% TW). Regarding the percentage of chemical fertilizers provided by the use of TWST and WTCW, based on the supply and nutritional recommendation for the crops, considering only the macronutrients nitrogen (N), phosphorus (P) and potassium (K), TWST and WTCW, were able to partially meet the nutritional needs of lettuce and beet (N, P and K) and fully of radish regarding to N and partially of P and K. From the evaluated uniformity coefficients, it was possible to affirm that TWST and WTCW did not compromise the uniformity of water application, and comparing the evaluation of the irrigation system operating with WTCW and TWST, the performance was better with WTCW, due to the lower concentration of suspended solids and total coliforms, consequently, lower susceptibility to emitters obstruction. Therefore, both systems are able to provide TW for vegetable through drip irrigation, within the physicochemical and microbiological standards established in the Brazilian legislation, favoring crop development, as well as providing an alternative source of plant nutrients and water for crops irrigation.
Human activities in general are extremely dependent on water. However, the use of this indispensable resource in power generation, supply, industry and agriculture, when improperly performed, may compromise its quality. Thus, it is necessary to incorporate the practice of reuse in irrigation, using for example, treated wastewater (TW). Thus, the objectives of this work were: to evaluate the feasibility of using wastewater treated by two distinct systems, septic tank + SODIS + 125 mg L-1 H2O2 (TWST) and constructed wetlands (WTCW), through drip irrigation in lettuce, beet and radish crops in terms of yield, Escherichia coli contamination, and water use efficiency (WUE); calculate the percentage of macronutrients provided by TWST and WTCW; and verify the uniformity of the irrigation system operating with TWST and WTCW. The vegetables were field grown with five irrigation depth compositions 0, 25, 50, 75 and 100% TWST and WTCW. During the conduction of the experiment, physical, chemical and microbiological analyzes were performed at TW. After harvesting, biometric, yield and microbiological analyzes were performed on the vegetable samples, as well as the uniformity of the irrigation system. Irrigation with TWST and WTCW provided better yield of all vegetables compared to conventional planting (0% TW). Both evaluated systems and the four irrigation depth compositions (with TW) made it possible to produce vegetables free of E. coli contamination, classifying them as suitable for raw human consumption. For the three evaluated crops irrigated with TWST and WTCW, the WUE values were higher when compared to the conventional system (0% TW). Regarding the percentage of chemical fertilizers provided by the use of TWST and WTCW, based on the supply and nutritional recommendation for the crops, considering only the macronutrients nitrogen (N), phosphorus (P) and potassium (K), TWST and WTCW, were able to partially meet the nutritional needs of lettuce and beet (N, P and K) and fully of radish regarding to N and partially of P and K. From the evaluated uniformity coefficients, it was possible to affirm that TWST and WTCW did not compromise the uniformity of water application, and comparing the evaluation of the irrigation system operating with WTCW and TWST, the performance was better with WTCW, due to the lower concentration of suspended solids and total coliforms, consequently, lower susceptibility to emitters obstruction. Therefore, both systems are able to provide TW for vegetable through drip irrigation, within the physicochemical and microbiological standards established in the Brazilian legislation, favoring crop development, as well as providing an alternative source of plant nutrients and water for crops irrigation.
Descrição
Palavras-chave
SODIS, Irrigação, Reutilização, Produtividade, Qualidade microbiológica, Uniformidade, Irrigation, Reuse, Productivity, Microbiological quality, Uniformity