ABSTRACT
RESUMO Os antibióticos como o norfloxacino constituem os fármacos mais utilizados na Medicina, com consumos expressivos no mundo todo. Por ser quimicamente estável, após sua administração a maior parte do fármaco é excretada de forma inalterada e, geralmente, é removida apenas parcialmente nas estações de tratamento de esgoto (ETEs). Assim, o presente trabalho buscou avaliar a eficiência dos processos biológicos na remediação de norfloxacino investigando os mecanismos de remoção envolvidos. O objetivo foi verificar a biodegradabilidade do fármaco e sua toxicidade. Para realização dos ensaios de biodegradabilidade, coletaram-se lodos na ETE Arrudas (Sabará, Minas Gerais) dos processos de tratamento com lodos ativados, reatores upflow anaerobic sludge blanket (UASB) e biodigestor anaeróbio. Reatores em escala de bancada foram montados com lodo aclimatado e não aclimatado. Amostras tiveram a biodegradabilidade acompanhada por meio da determinação do carbono orgânico total e da absortividade molar do norfloxacino por espectrofotometria de UV/Vis. Determinou-se a toxicidade por intermédio de ensaios com a bactéria Aliivibrio fischeri. Entre as biomassas utilizadas, a mais eficiente na remoção do norfloxacino foi advinda dos reatores UASB (23%), seguida do biodigestor anaeróbio (18%) e, então, dos lodos ativados (13%). Quanto à ecotoxicidade, a degradação anaeróbia promoveu a eliminação da toxicidade do antibiótico, enquanto com relação à degradação aeróbia os efluentes gerados permanecem tóxicos.
ABSTRACT Antibiotics, such as norfloxacin, are the most widely used drugs in medicine, with significant consumption in the world. By being chemically stable, most of the drug is excreted unchanged after administration, and is generally only partially removed in the sewage treatment plants (STPs). Thus, the efficiency of biological processes in the remediation of norfloxacin was investigated by the present work, verifying the removal mechanisms involved. Its objective was to verify the drug's biodegradability and toxicity. In order to perform biodegradability tests, sludges were collected in Arrudas STP (Sabara, Minas Gerais) from the treatment processes with activated sludge, upflow anaerobic sludge blanket (UASB) reactors and anaerobic biodigester. Bench-scale reactors were assembled with acclimatized and non-acclimatized sludge. Samples had their biodegradability monitored by determination of total organic carbon and norfloxacin molar absorptivity by UV/Vis spectrophotometry. The toxicity was determined by tests with Aliivibrio fischeri. Among the used biomass, UASB reactors was the most efficient in removing norfloxacin (23%), followed by anaerobic biodigester (18%), and activated sludge (13%). Regarding ecotoxicity, the anaerobic degradation promoted the elimination of antibiotic toxicity, while with aerobic degradation, the effluents generated remained toxic.
ABSTRACT
RESUMO A avaliação de risco é um processo no qual se determinam os riscos de natureza coletiva (social) e individual associados à instalação, operação ou desativação de uma atividade perigosa, levando-se em consideração a probabilidade de ocorrência de um determinado evento e a estimativa da extensão do dano que seria causado. No caso de estações de tratamento de esgoto (ETEs), em que pese a importância do aspecto locacional para assegurar a minimização de conflitos ambientais e sociais, a análise de risco deve ser parte integrante dos estudos de alternativas locacionais quando a concepção do projeto prever a utilização de substâncias perigosas armazenadas sob pressão, notadamente os sistemas de desinfecção por cloro. Entende-se, portanto, ser necessário avaliar o potencial de dano decorrente de falhas nos equipamentos e dispositivos de segurança que possam provocar vazamentos e/ou explosões. Nesse sentido, o presente artigo discute as contribuições dos estudos de análise de risco na implantação e operação de ETEs, valendo-se de um estudo de caso aplicado ao município de São José do Rio Preto, São Paulo. Os resultados obtidos destacam a relevância do estudo de análise de risco para a definição da localização do empreendimento e de medidas de segurança aplicadas ao gerenciamento da ETE e das áreas do entorno.
ABSTRACT Risk analysis allows for the identification of social and individual risks following the installation, operation or decommissioning of a hazardous activity, taking into account the probability of occurrence and the extension of damages. Sewage Treatment Plants with disinfection systems must be informed by a risk analysis in order to integrate social and environmental conflicts in decision-making. Therefore, it is relevant to assess the potential to cause relevant damage caused by failures in equipment or security devices that could lead to leakages and/or explosions. In this sense, the present paper discuss the results of a risk assessment applied to the Sewage Treatment Plant of São Jose do Rio Preto (SP). The results show the relevance of risk analysis in defining the locational alternative and the associated security measures applied to risk and conflict management, considering the plant itself, the environment and neighboring population.
ABSTRACT
Municipal sewage treatment plants (STPs) are thought to be important point sources of microplastics in freshwater systems and many peer-reviewed articles have been published on this issue since mid-2010s. In this review, we summarize existing literature on the occurrence of microplastics in STPs and experimental methods used for isolation and identification of microplastics. The number concentrations of microplastics in STP influents were 15.1-640 L⁻¹, whereas those in the STP effluents were highly variable and ranged from not detectable to 65 L⁻¹. For most of cases, conventional STPs are removing microplastics very effectively. Fragments and fibers are dominant shapes of microplastics. Thermoplastics (polyethylene and polypropylene) and polyester are the predominant materials recovered. Although further research is needed, size distribution of microplastics in STPs is likely to follow a power law, implying that different studies using different size cutoffs may be compared after establishing a power law relationship.
Subject(s)
Fresh Water , Jurisprudence , Polyesters , SewageABSTRACT
Municipal sewage treatment plants (STPs) are thought to be important point sources of microplastics in freshwater systems and many peer-reviewed articles have been published on this issue since mid-2010s. In this review, we summarize existing literature on the occurrence of microplastics in STPs and experimental methods used for isolation and identification of microplastics. The number concentrations of microplastics in STP influents were 15.1-640 L⁻¹, whereas those in the STP effluents were highly variable and ranged from not detectable to 65 L⁻¹. For most of cases, conventional STPs are removing microplastics very effectively. Fragments and fibers are dominant shapes of microplastics. Thermoplastics (polyethylene and polypropylene) and polyester are the predominant materials recovered. Although further research is needed, size distribution of microplastics in STPs is likely to follow a power law, implying that different studies using different size cutoffs may be compared after establishing a power law relationship.