Análise da remoção/recuperação de nutrientes em pós-tratamento de esgoto sanitário via consórcio microalgas-bactérias em reator flatpanel em escala piloto por bateladas
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Data
2023-01-06
Autores
Miguel, Eduardo Marques
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Universidade Estadual Paulista (Unesp)
Resumo
No modelo centralizado de saneamento adotado atualmente há elevado custo de implantação, operação e manutenção, além da desvalorização de resíduos e nutrientes presentes no efluente. Um novo modelo descentralizado e preocupado em reaproveitar subprodutos do tratamento apresenta-se como alternativa viável e sustentável. Os sistemas anaeróbios de tratamento destacam-se entre as soluções descentralizadas pela sua simplicidade, potencial de reaproveitamento energético e baixo custo, porém, não são eficazes na remoção de nutrientes e geralmente requerem pós-tratamentos associados. Somado a isso, a aplicação de biorreatores com microalgas como único tratamento pode ter eficácia prejudicada por altos níveis de matéria orgânica, sendo muito vantajosa sua aplicação como pós-tratamento de reatores anaeróbios. Ao utilizar microalgas no tratamento de esgoto sanitário, os nutrientes que outrora contribuiriam para eutrofização de corpos d’água receptores são removidos e fixados na biomassa algal, possibilitando ainda seu reaproveitamento em produtos de interesse da sociedade. No contexto global de intensificação da demanda agrícola por fertilizantes a base de nitrogênio, fósforo e potássio, fontes alternativas são almejadas. Neste cenário, este trabalho visa contribuir com a base técnico-científica sobre o tema, estudando a influência exercida pela temperatura e intensidade luminosa na remoção de nutrientes e no desenvolvimento da biomassa algal em um reator instalado ao ar livre. Para isso, foi introduzido esgoto tratado anaerobiamente em um fotobiorreator do tipo flat panel de dimensões 1,2x0,6x0,1m operando com volume de 50 L e inoculado com consórcio adaptado de microalgas-bactérias nativas obtidas no esgoto em questão. O regime de operação foi em bateladas de 7 dias e ao longo de cada ciclo foram retiradas amostras para verificar a qualidade do efluente em termos de nutrientes dissolvidos e biomassa algal. Foram realizadas análises estatísticas à partir dos dados coletados e verificada a magnitude da influência exercida por cada variável através de métodos de regressão. Foram desenvolvidos sete modelos por regressão linear simples, relacionando variáveis correlacionáveis do tratamento e três modelos por regressão múltipla que melhor explicaram as taxas de remoção de nitrogênio, fósforo e produção de biomassa. Foram encontradas fortes correlações entre variáveis de iluminação com a remoção de nitrogênio inorgânico e pH com o fósforo total. Também foi verificado efeito significativo das concentrações iniciais dos nutrientes em suas taxas de remoção médias diárias.
Today’s sewage and sanitation systems focus efforts in centralizing the wastewater generated by a whole region in a single area for treatment, it incurs high costs both building and maintaining, apart from the waste of potential valuable resources present in wastewater. A decentralized reuseorientated model presents itself as a viable and sustainable alternative. In such case, anaerobic treatment systems could be the system of choice because of its innate simplicity and huge recycling potential. In this regard, anaerobic system’s nutrient removal inefficiency, one of its most notable flaw, could be beneficially exploited if associated with post-treatment focused in nutrient recovery. Microalgae bioreactors have the necessary features to fulfill this role as post-treatment, with nutrients that would otherwise cause rivers eutrophication being recovered by microalgae. Stored nutrients could be applied in other fields of society, like biofuels and bioplastics or in agriculture as biofertilizers. In this scenario, this work aims to contribute as technical-scientific base, studying the influence of light intensity and temperature in the process of nutrient removal and biomass growth in an outdoor reactor. To assess the problem, anaerobically treated sewage was used as substract in an outdoor flat panel photobioreactor with dimensions of 1.2x0.6x0.1m, operating with a volume of 50 L and inoculated with an adapted native microalgae-bacteria consortium obtained from the used sewage. The PBR was operated in a 7-day batch regime, and samples were taken throughout each cycle to check the quality of the effluent in terms of dissolved nutrients and algal biomass. Statistical analyses were performed on the collected data, and the magnitude of the influence exerted by each variable was verified through regression methods. Seven models were developed using simple linear regression, relating correlated variables of the treatment. Three models were developed using multiple linear regression to explain removal rates of nitrogen and phosphorus and biomass production. Strong correlations were found between lighting variables and inorganic nitrogen removal, and pH and total phosphorus. Significant effect of initial nutrient concentrations on their average daily removal rates was also verified.
Today’s sewage and sanitation systems focus efforts in centralizing the wastewater generated by a whole region in a single area for treatment, it incurs high costs both building and maintaining, apart from the waste of potential valuable resources present in wastewater. A decentralized reuseorientated model presents itself as a viable and sustainable alternative. In such case, anaerobic treatment systems could be the system of choice because of its innate simplicity and huge recycling potential. In this regard, anaerobic system’s nutrient removal inefficiency, one of its most notable flaw, could be beneficially exploited if associated with post-treatment focused in nutrient recovery. Microalgae bioreactors have the necessary features to fulfill this role as post-treatment, with nutrients that would otherwise cause rivers eutrophication being recovered by microalgae. Stored nutrients could be applied in other fields of society, like biofuels and bioplastics or in agriculture as biofertilizers. In this scenario, this work aims to contribute as technical-scientific base, studying the influence of light intensity and temperature in the process of nutrient removal and biomass growth in an outdoor reactor. To assess the problem, anaerobically treated sewage was used as substract in an outdoor flat panel photobioreactor with dimensions of 1.2x0.6x0.1m, operating with a volume of 50 L and inoculated with an adapted native microalgae-bacteria consortium obtained from the used sewage. The PBR was operated in a 7-day batch regime, and samples were taken throughout each cycle to check the quality of the effluent in terms of dissolved nutrients and algal biomass. Statistical analyses were performed on the collected data, and the magnitude of the influence exerted by each variable was verified through regression methods. Seven models were developed using simple linear regression, relating correlated variables of the treatment. Three models were developed using multiple linear regression to explain removal rates of nitrogen and phosphorus and biomass production. Strong correlations were found between lighting variables and inorganic nitrogen removal, and pH and total phosphorus. Significant effect of initial nutrient concentrations on their average daily removal rates was also verified.
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Palavras-chave
Tratamento anaeróbio, Fotobiorreator, Microalgas, Regressão linear, Modelagem, Anaerobic treatment, Photobioreactor, Microalgae, Linear regression, Modelling