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De efluente de suinicultura a biomassa para aplicação na agricultura. Tratamento com Tetradesmus obliquus
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Resumo(s)
O aumento intensivo das produções agrícola e pecuária têm contribuído para vários problemas ambientais. O tratamento de efluentes com microalgas pode ser uma tecnologia promissora, substituta ou complementar ao tratamento convencional. Permite não só o tratamento, como também a recuperação de nutrientes, com possível valorização da biomassa microalgal. O pré-tratamento foto-Fenton (PF) no efluente suinícola (PWW) foi eficaz na diminuição da matéria orgânica (91%) e da cor escura (86%).
O tratamento de PWW pela microalga Tetradesmus obliquus (To) foi avaliado em modo semi-contínuo para diferentes percentagens e tipo de efluente: pré-tratado a 20 e 10% (PF_20 e PF_10) e não tratado a 5 e 10% (PWW_5 e PWW_10). Um tempo de retenção de 3 dias para PF_20 e PF_10 não foi suficiente para diminuir o teor de azoto dentro do estipulado (15 mg N L-1). Para PF_5 atingiu-se remoções de azoto até 87%, possivelmente, devido à volatilização do NH3. Não se verificou crescimento de To em PWW_10. Com o objetivo de se otimizar o crescimento de To em efluente PF, foram testadas duas intensidades de luz (50 e 150 μmol m-2 s-1) e a manutenção do pH com tampão TRIS: PF_50, PF_150, PF_TRIS_50 e PF_TRIS_150. Para uma intensidade de luz superior verificou-se um menor crescimento, mas a manutenção do pH não influenciou, significativamente, o crescimento de To.
Nos ensaios de germinação, foram obtidos índices de germinação de 120-150% com To, enquanto que os sobrenadantes forneceram nutrientes essenciais para o crescimento do trigo. O concentrado do PF permitiu obter um maior número de espigas, equiparável ao controlo positivo (6,0 ± 4,1 vs. 5,7 ± 1,4).
As culturas de To (1, 2,5 e 5 g L-1) crescidas em efluente PF com e sem disrupção celular não apresentaram efeito biopesticida contra o fungo Rhizoctonia solani. Para Fusarium oxysporum, nas mesmas condições, os resultados foram inconclusivos devido a contaminações biológicas.
The intensive growth of agriculture and livestock has led to many environmental problems. Wastewater treatment with microalgae could be a promising technology, replacing or complementing the conventional treatment. Allows not only the treatment, but also the recovery of nutrients, with possibility of valorization of the microalgal biomass. The pre-treatment photo-Fenton (PF) on the effluent (PWW) is effective on decreasing the organic matter (91%) and dark color (86%). The PWW treatment with the microalga Tetradesmus obliquus (To) was evaluated in semi-batch mode for different percentages and type of effluent: pre-treated at 20 and 10% (PF_20 and PF_10) and non-treated at 5 and 10% (PWW_5 and PWW_10). The retention time of 3 days for PF_20 and PF_10 was not sufficient to remove the ammonia up to legally allowed (15 mg N L-1). For PF_5 a removal of 87% was obtained, probably due to NH3 volatilization. To did not grow at PWW_10. To optimize culture growth, two light intensities were tested (50 and 150 μmol m-2 s-1) as well as pH maintenance with buffer solution TRIS: PF_50, PF_150, PF_TRIS_50 and PF_TRIS_150. For higher light intensity, a lower growth rate was obtained, while the pH maintenance did not significantly affect the growth of To. In germination trials, high germination index values were obtained (120-150%) with To biomass, while the supernatants provided essential nutrients for wheat growth. The concentrate from PF allowed the highest number of cobs, equivalent to the synthetic positive control (6.0 ± 4.1 vs. 5.7 ± 1.4). The microalga To (1, 2.5 and 5 g L-1) grown in PF, with and without disruption, did not show any biopesticide effect against the fungus Rhizoctonia solani. For Fusarium oxysporum, in the same conditions, the results were inconclusive due to biological contamination.
The intensive growth of agriculture and livestock has led to many environmental problems. Wastewater treatment with microalgae could be a promising technology, replacing or complementing the conventional treatment. Allows not only the treatment, but also the recovery of nutrients, with possibility of valorization of the microalgal biomass. The pre-treatment photo-Fenton (PF) on the effluent (PWW) is effective on decreasing the organic matter (91%) and dark color (86%). The PWW treatment with the microalga Tetradesmus obliquus (To) was evaluated in semi-batch mode for different percentages and type of effluent: pre-treated at 20 and 10% (PF_20 and PF_10) and non-treated at 5 and 10% (PWW_5 and PWW_10). The retention time of 3 days for PF_20 and PF_10 was not sufficient to remove the ammonia up to legally allowed (15 mg N L-1). For PF_5 a removal of 87% was obtained, probably due to NH3 volatilization. To did not grow at PWW_10. To optimize culture growth, two light intensities were tested (50 and 150 μmol m-2 s-1) as well as pH maintenance with buffer solution TRIS: PF_50, PF_150, PF_TRIS_50 and PF_TRIS_150. For higher light intensity, a lower growth rate was obtained, while the pH maintenance did not significantly affect the growth of To. In germination trials, high germination index values were obtained (120-150%) with To biomass, while the supernatants provided essential nutrients for wheat growth. The concentrate from PF allowed the highest number of cobs, equivalent to the synthetic positive control (6.0 ± 4.1 vs. 5.7 ± 1.4). The microalga To (1, 2.5 and 5 g L-1) grown in PF, with and without disruption, did not show any biopesticide effect against the fungus Rhizoctonia solani. For Fusarium oxysporum, in the same conditions, the results were inconclusive due to biological contamination.
Descrição
Mestrado em Engenharia do Ambiente. Universidade de Lisboa, Instituto Superior de Agronomia
Palavras-chave
microalgas tratamento de efluente de suinicultura bioestimulantes biofertilizantes e biopesticidas microalgae piggery wastewater treatment biostimulants biofertilizers and biopesticides
Contexto Educativo
Citação
Marujo, A.P.M.C. De efluente de suinicultura a biomassa para aplicação na agricultura. Tratamento com Tetradesmus obliquus. Lisboa: ISA-Universidade de Lisboa, 2023. Dissertação de Mestrado
Editora
Instituto Superior de Agronomia, Universidade de Lisboa