Aproveitamento de efluente gerado na biodigestão anaeróbia de resíduos orgânicos de origem doméstica na agricultura irrigada
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Data
2022-07-28
Autores
Machado, Letícia Thália Silva
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Universidade Estadual Paulista (Unesp)
Resumo
O digestato obtido através do processo de digestão anaeróbia pode ser aproveitado e benéfico na produção agrícola, no entanto, existem poucas informações e recomendações para um uso seguro desse subproduto na agricultura. À vista disso, objetivou-se com este trabalho realizar a caracterização e aplicação de um efluente, obtido a partir do tratamento anaeróbio de resíduos alimentares, na produção de alface, avaliando seus efeitos na cultura e no sistema de irrigação localizada por gotejamento. Para isso, utilizaram-se dois reatores anaeróbios, um biodigestor comercial e um sistema de filtros anaeróbios verticais descendentes (SFAV), adotado como pós-tratamento para o digestato obtido do biodigestor. As características físico-químicas e biológicas dos efluentes obtidos pelos dois sistemas utilizados foram analisadas. A partir dos resultados, constatou-se que o efluente obtido pelo SFAV tinha características mais adequadas do que o obtido pelo biodigestor para uso na fertirrigação de alface Crespa Vera (Lactuca sativa L.). Dessa forma, foi determinada uma dosagem de aplicação desse biofertilizante para atender à demanda potássica de cobertura da alface. O ensaio experimental foi de blocos casualizados e consistiu em 5 tratamentos e 5 repetições, sendo T1 – NPK mineral recomendado (testemunha); T2 – biofertilizante + NP mineral; T3 – biofertilizante + N mineral; T4 – biofertilizante + P mineral e T5 – biofertilizante. Para fornecer apenas os elementos químicos de interesse em cada tratamento foi necessário utilizar diferentes fontes de adubo, dispondo no T1: MAP, KNO3 e uréia, T2: MAP e uréia, T3: uréia e T4: H3PO4. As dosagens dos adubos foram definidas seguindo as recomendações do IAC. Ao final do ciclo da cultura, foram avaliadas suas propriedades biométricas, nutricionais e microbiológicas. A avaliação do desempenho do sistema de irrigação foi feita no início, meio e fim do ciclo da cultura através do teste de uniformidade de aplicação de água. A partir dos resultados obtidos constatou-se que tanto o digestato do biodigestor quanto o biofertilizante obtido pelo SFAV apresentaram características interessantes para o uso agrícola. O biofertilizante obtido do SFAV apresentou características mais apropriadas após diluição de 1:6 para o uso em sistema de irrigação localizada. Quanto à produção da alface, os tratamentos que fizeram o uso do biofertilizante apresentaram rendimentos de massa fresca, massa seca e diâmetro de copa superiores ao tratamento adubado com o fertilizante mineral. Ainda, o uso do biofertilizante gerou aumento do teor de Ca foliar e obteve teores médios de N, P, K e Mg próximos ao tratamento adubado com fertilizante mineral. As contagens de bactérias presentes nos biofertilizantes não resultaram em contagem de E. coli nas alfaces. Em nenhum dos tratamentos as alfaces apresentaram contagem de E. coli e Salmonella spp., atendendo aos padrões sanitários exigidos pela legislação brasileira. Conclui-se que o biofertilizante, sob diluição de 1:6, apresentou efeitos satisfatórios para a produção da alface, podendo substituir a adubação mineral de cobertura sem que haja prejuízo na produtividade, não gerou alfaces danosas ao consumo humano in natura, uma vez que não manifestou presença de microrganismos patogênicos, e não gerou prejuízos no sistema de irrigação localizada durante o tempo de operação utilizado neste projeto.
The digestate obtained through the anaerobic digestion process can be used and beneficial in agricultural production, however, there is few information and recommendations for a safe use of this by-product in agriculture. The objective of this work was to carry out the characterization and application of an effluent, obtained from the anaerobic treatment of food waste, in the production of lettuce, evaluating its effects on the crop and on the drip irrigation system. For this, were used two anaerobic reactors, a commercial digester and a vertical descending anaerobic filters system (SFAV), adopted as post-treatment for the digestate obtained from the biodigester. The physical-chemical and biological characteristics of the effluents obtained by the two systems used were analyzed. From the results, it was found that the effluent obtained by the SFAV had more suitable characteristics than that obtained by the biodigester for use in the fertigation of lettuce Lactuca sativa L. Thus, a dosage of application of this biofertilizer was determined to meet the cover potassium demand of lettuce. The experimental trial was randomized blocks and consisted of 5 treatments and 5 replications, being T1 – mineral NPK recommended (control); T2 – biofertilizer + mineral NP; T3 – biofertilizer + mineral N; T4 – biofertilizer + mineral P and T5 – biofertilizer. To supply only the chemical elements of interest in each treatment, it was necessary to use different sources of fertilizer, with T1: MAP, KNO3 and urea, T2: MAP and urea, T3: urea and T4: H3PO4. Fertilizer dosages were defined following the recommendations of the IAC. At the end of the culture cycle, its biometric, nutritional and microbiological properties were evaluated. The evaluation of the irrigation system performance was carried out at the beginning, middle and end of the crop cycle through the test of uniformity of water application. From the results obtained, it was found that both the digestate of the biodigestor and the biofertilizer obtained by SFAV showed interesting characteristics for agricultural use. The biofertilizer obtained from SFAV showed more appropriate characteristics after dilution of 1:6 for use in a localized irrigation system. As for lettuce production, the treatments that used the biofertilizer showed yields of fresh mass, dry mass and crown diameter higher than the treatment fertilized with mineral fertilizer. Furthermore, the use of biofertilizer generated an increase in foliar Ca content and obtained average levels of N, P, K and Mg close to the treatment fertilized with mineral fertilizer. The bacterial counts present in the biofertilizers did not result in E. coli counts in the lettuces. In none of the treatments, the lettuces showed counts of E. coli and Salmonella spp., meeting the sanitary standards required by Brazilian legislation. With this, it is concluded that the biofertilizer, at a dilution of 1:6, presented satisfactory effects for the production of lettuce, being able to replace the mineral fertilization of cover without prejudice to productivity, it did not generate lettuces harmful to human consumption in natura, since it did not show the presence of pathogenic microorganisms, and did not generate losses in the localized irrigation system during the operating time used in this project.
The digestate obtained through the anaerobic digestion process can be used and beneficial in agricultural production, however, there is few information and recommendations for a safe use of this by-product in agriculture. The objective of this work was to carry out the characterization and application of an effluent, obtained from the anaerobic treatment of food waste, in the production of lettuce, evaluating its effects on the crop and on the drip irrigation system. For this, were used two anaerobic reactors, a commercial digester and a vertical descending anaerobic filters system (SFAV), adopted as post-treatment for the digestate obtained from the biodigester. The physical-chemical and biological characteristics of the effluents obtained by the two systems used were analyzed. From the results, it was found that the effluent obtained by the SFAV had more suitable characteristics than that obtained by the biodigester for use in the fertigation of lettuce Lactuca sativa L. Thus, a dosage of application of this biofertilizer was determined to meet the cover potassium demand of lettuce. The experimental trial was randomized blocks and consisted of 5 treatments and 5 replications, being T1 – mineral NPK recommended (control); T2 – biofertilizer + mineral NP; T3 – biofertilizer + mineral N; T4 – biofertilizer + mineral P and T5 – biofertilizer. To supply only the chemical elements of interest in each treatment, it was necessary to use different sources of fertilizer, with T1: MAP, KNO3 and urea, T2: MAP and urea, T3: urea and T4: H3PO4. Fertilizer dosages were defined following the recommendations of the IAC. At the end of the culture cycle, its biometric, nutritional and microbiological properties were evaluated. The evaluation of the irrigation system performance was carried out at the beginning, middle and end of the crop cycle through the test of uniformity of water application. From the results obtained, it was found that both the digestate of the biodigestor and the biofertilizer obtained by SFAV showed interesting characteristics for agricultural use. The biofertilizer obtained from SFAV showed more appropriate characteristics after dilution of 1:6 for use in a localized irrigation system. As for lettuce production, the treatments that used the biofertilizer showed yields of fresh mass, dry mass and crown diameter higher than the treatment fertilized with mineral fertilizer. Furthermore, the use of biofertilizer generated an increase in foliar Ca content and obtained average levels of N, P, K and Mg close to the treatment fertilized with mineral fertilizer. The bacterial counts present in the biofertilizers did not result in E. coli counts in the lettuces. In none of the treatments, the lettuces showed counts of E. coli and Salmonella spp., meeting the sanitary standards required by Brazilian legislation. With this, it is concluded that the biofertilizer, at a dilution of 1:6, presented satisfactory effects for the production of lettuce, being able to replace the mineral fertilization of cover without prejudice to productivity, it did not generate lettuces harmful to human consumption in natura, since it did not show the presence of pathogenic microorganisms, and did not generate losses in the localized irrigation system during the operating time used in this project.
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Palavras-chave
digestato, biofertilizante, alface, filtro anaeróbico vertical descendente, biodigestores, digestate, lettuce, biofertilizer, vertical descending anaerobic filter