Reúso de efluente de estação de tratamento de esgoto tratado em filtros anaeróbios verticais aplicado na alface irrigada por gotejamento
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Data
2022-06-09
Autores
Leroy, Karl Auguste
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Universidade Estadual Paulista (Unesp)
Resumo
A escassez dos recursos hídricos e a deterioração de sua qualidade são um grande desafio do século XXI. Nesse contexto, a busca por alternativas sustentáveis para manter e ampliar a produção agrícola global torna-se essencial para enfrentar esse reto. O reaproveitamento de águas residuárias tratadas é uma das possíveis soluções locais a serem implementadas para enfrentar os desafios específicos relacionados a escassez hídrica ou para adaptar-se às pressões sazonais sobre a água, sejam elas quantitativas ou qualitativas. Esta solução pode ser utilizada em conjunto com outras medidas de gestão equilibrada dos recursos hídricos. Mediante o exposto, objetivou-se, neste trabalho, avaliar os efeitos da disposição da água residuária tratada em filtros anaeróbios verticais em diferentes proporções na irrigação por gotejamento de um sistema solo / alface. O experimento foi conduzido em campo no Departamento de Engenharia Rural e Socioeconomia (DERS), da Faculdade de Ciências Agronômicas (FCA) - Universidade Estadual Paulista (UNESP), no município de Botucatu-SP, em delineamento inteiramente ao acaso, sendo constituído por cinco tratamentos e cinco repetições. Os tratamentos foram compostos por cinco diferentes proporções de lâmina de irrigação preparadas a partir de duas fontes de água, sendo uma de abastecimento (AA) e outra residuária tratada (ART), resultando em: T1 – 100%ART, T2 - 75%ART + 25%AA, T3 - 50%ART + 50%AA, T4 - 25%ART + 75%AA, T5 – 100%AA. Realizaram-se dois ciclos de cultivo de alface durante o período de setembro a dezembro de 2021 e os resultados obtidos foram analisados estatisticamente. Realizaram-se durante a condução do experimento análises físicas, químicas e microbiológicas na água residuária e na água de abastecimento. No final dos ciclos, foram realizadas análises biométricas, microbiológicas, e a análise nutricional foi realizada apenas no final do segundo ciclo. Nas amostras de solo, retiradas no ínicio e no final de cada ciclo, foram realizadas análises de pH (CaCl2), matéria orgânica (MO), fósforo (P), cálcio (Ca), magnésio (Mg), potássio (K), sódio (Na), boro (B), cobre (Cu), zinco (Zn), manganês (Mn) e ferro (Fe). Todos os tratamentos permitiram a produção de alface de qualidade dentro dos padrões estabelecidos pela Agência Nacional de Vigilância Sanitária (ANVISA) no que diz respeito a contaminação por Escherichia coli, classificando as plantas produzidas como aptas ao consumo humano in natura. Em relação às análises não destrutivas, observou-se diferença significativa pelo teste de Tukey a 5% de probabilidade entre os tratamentos estudados apenas para a massa seca durante o primeiro ciclo de cultivo, sendo T4 (25% ART + 75% AA) o tratamento que apresentou melhor resultado. Quanto à análise nutricional das plantas não foram observadas diferenças nos teores dos nutrientes nas folhas das plantas produzidas. No entanto, os teores dos nutrientes fósforo, potássio, cálcio, magnésio e boro encontram-se abaixo das faixas de concentração adequadas para a cultura em todos os tratamentos. Nas propriedades químicas do solo dos diferentes tratamentos estudados no primeiro ciclo, observou-se aumento nas concentrações do fósforo, sódio, cálcio, cobre, ferro, zinco e redução nos teores de boro e da matéria orgânica em relação ao estado inicial. Quanto ao pH do solo e os elementos potássio e magnésio verificaram-se alterações nos diferentes tratamentos em relação ao estado inicial. No segundo ciclo, nos diferentes tratamentos estudados, houve aumento nas concentrações de fósforo, sódio, cobre, ferro, zinco, matéria orgânica e redução nos valores de pH, cálcio, magnésio e boro em relação ao estado inicial. Quanto ao elemento potássio, no segundo ciclo, verificou-se redução em todos os tratamentos estudados, exeto no tratamento T1 que houve aumento. Os resultados obtidos demonstram a possibilidade do uso da água residuária tratada em filtros aneoróbios verticais, como fonte de água e nutrientes para o cultivo de alface de qualidade para consumo humano, diminuindo as adubações com fertilizantes químicos comerciais e reduzindo os custos de produção, tornando a irrigação e o cultivo mais econômicos.
The scarcity of water resources and the deterioration of their quality are a major challenge in the 21st century. In this context, the search for sustainable alternatives to maintain and expand global agricultural production becomes essential to face this challenge. The reuse of treated wastewater is one of the possible local solutions to be implemented to face the specific challenges related to water scarcity or to adapt to seasonal pressures on water, whether quantitative or qualitative. This solution can be used in conjunction with other measures for the balanced management of water resources. Based on the above, the objective of this work was to evaluate the effects of the disposal of treated wastewater in vertical anaerobic filters in different proportions in drip irrigation of a soil / lettuce system.The field experiment was carried out at the Department of Rural Engineering and Socioeconomics (DERS), Faculty of Agricultural Sciences (FCA) - Universidade Estadual Paulista (UNESP), in the city of Botucatu-SP. It was a completely randomized design, consisting of five treatments and five repetitions. The treatments were composed of five different proportions of irrigation depths prepared from two sources of water, one being a supply (SW) and another wastewater (TWW), resulting in: T1 - 100%TWW, T2 - 75%TWW + 25%SW, T3 - 50%TWW + 50%SW, T4 - 25%TWW + 75%SW, T5 - 100%SW. Two lettuce cultivation cycles were carried out during the period from September to December 2021 and the results obtained were statistically analyzed. During the experiment, physical, chemical and microbiological analyzes were carried out in the wastewater and in the supply water. At the end of the cycles, biometric, microbiological and nutritional analyzes were carried out on the vegetable samples, the latter being performed only at the end of the second cycle. In the soil samples, taken at the beginning and end of each cycle, analyzes of pH (CaCl2), organic matter (MO), phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), boron (B), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe). The treatments implemented allowed quality lettuce production within the standards established by National Health Surveillance Agency (ANVISA) with regard to contamination by Escherichia coli, classifying the plants produced as suitable for human consumption in natura. Regarding the non-destructive analyses, a significant difference was observed by the Tukey test at 5% of probability between the treatments studied only for the dry mass during the first cultivation cycle, with T4 (25%TWW + 75%SW) the treatment which showed the best result. Regarding the nutritional analysis of the plants, no differences were observed in the nutrient contents in the plants’ leaves. However, the contents of the nutrients phosphorus, potassium, calcium, magnesium and boron were below the concentration ranges suitable for the crop in all treatments. The chemical properties soil for different treatments in the first cycle, showed an increase in the concentrations of phosphorus, sodium, calcium, copper, iron, zinc and a reduction in boron and organic matter contents in relation to the initial state. As for the soil’s pH and the elements potassium and magnesium, alterations were verified in the different treatments in relation to the initial state. For the second cycle, in the different treatments studied, there was an increase in the concentrations of phosphorus, sodium, copper, iron, zinc, organic matter and a reduction in the values of pH, calcium, magnesium and boron in relation to the initial state. As for the potassium element, in the second cycle, there was a reduction in all the treatments studied, except for the T1 treatment, which had an increase. The results obtained demonstrate the possibility of using wastewater treated in vertical anaerobic filters as a source of water and nutrients for the cultivation of quality lettuce for human consumption, reducing fertilization with commercial chemical fertilizers and reducing production costs, making irrigation and cultivation more economical.
The scarcity of water resources and the deterioration of their quality are a major challenge in the 21st century. In this context, the search for sustainable alternatives to maintain and expand global agricultural production becomes essential to face this challenge. The reuse of treated wastewater is one of the possible local solutions to be implemented to face the specific challenges related to water scarcity or to adapt to seasonal pressures on water, whether quantitative or qualitative. This solution can be used in conjunction with other measures for the balanced management of water resources. Based on the above, the objective of this work was to evaluate the effects of the disposal of treated wastewater in vertical anaerobic filters in different proportions in drip irrigation of a soil / lettuce system.The field experiment was carried out at the Department of Rural Engineering and Socioeconomics (DERS), Faculty of Agricultural Sciences (FCA) - Universidade Estadual Paulista (UNESP), in the city of Botucatu-SP. It was a completely randomized design, consisting of five treatments and five repetitions. The treatments were composed of five different proportions of irrigation depths prepared from two sources of water, one being a supply (SW) and another wastewater (TWW), resulting in: T1 - 100%TWW, T2 - 75%TWW + 25%SW, T3 - 50%TWW + 50%SW, T4 - 25%TWW + 75%SW, T5 - 100%SW. Two lettuce cultivation cycles were carried out during the period from September to December 2021 and the results obtained were statistically analyzed. During the experiment, physical, chemical and microbiological analyzes were carried out in the wastewater and in the supply water. At the end of the cycles, biometric, microbiological and nutritional analyzes were carried out on the vegetable samples, the latter being performed only at the end of the second cycle. In the soil samples, taken at the beginning and end of each cycle, analyzes of pH (CaCl2), organic matter (MO), phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), boron (B), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe). The treatments implemented allowed quality lettuce production within the standards established by National Health Surveillance Agency (ANVISA) with regard to contamination by Escherichia coli, classifying the plants produced as suitable for human consumption in natura. Regarding the non-destructive analyses, a significant difference was observed by the Tukey test at 5% of probability between the treatments studied only for the dry mass during the first cultivation cycle, with T4 (25%TWW + 75%SW) the treatment which showed the best result. Regarding the nutritional analysis of the plants, no differences were observed in the nutrient contents in the plants’ leaves. However, the contents of the nutrients phosphorus, potassium, calcium, magnesium and boron were below the concentration ranges suitable for the crop in all treatments. The chemical properties soil for different treatments in the first cycle, showed an increase in the concentrations of phosphorus, sodium, calcium, copper, iron, zinc and a reduction in boron and organic matter contents in relation to the initial state. As for the soil’s pH and the elements potassium and magnesium, alterations were verified in the different treatments in relation to the initial state. For the second cycle, in the different treatments studied, there was an increase in the concentrations of phosphorus, sodium, copper, iron, zinc, organic matter and a reduction in the values of pH, calcium, magnesium and boron in relation to the initial state. As for the potassium element, in the second cycle, there was a reduction in all the treatments studied, except for the T1 treatment, which had an increase. The results obtained demonstrate the possibility of using wastewater treated in vertical anaerobic filters as a source of water and nutrients for the cultivation of quality lettuce for human consumption, reducing fertilization with commercial chemical fertilizers and reducing production costs, making irrigation and cultivation more economical.
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Palavras-chave
água de irrigação, agricultura, contaminação, hortaliças, reutilização da água., irrigation water, agriculture, contamination, vegetables, water reuse