RESUMEN

In this study, mixed matrix hollow fiber polymeric membranes were prepared using polyethersulfone (PES) and polyvinylidene fluoride (PVDF) as polymers in their composition. N-methyl-2-pyrrolidone (NMP) was used as a solvent and demineralized water with an electrical conductivity below 3 µS·cm-1 was used as a non-solvent. A new approach to producing enhanced polymeric hollow fiber membranes based on the preparation of a simple blend PVDF/PES solution, and on the conformation of the composite membranes through the extrusion technique followed by the phase inversion process in a non-solvent bath, was applied. The investigation focused on the preparation of polymeric membranes with different polymer ratios and further assessment of the effects of these proportions on the membrane performance and in specific physical properties. The amount of PVDF ranged from 10 to 90% with 10% steps. The presence of PVDF, although it increased the membranes' plasticity, had a negative effect on the overall mechanical properties of the composite membranes. Scanning electron microscopy (SEM) results showed good dispersion of both polymers in the polymeric matrix. Furthermore, the membrane permeability showed a slight negative correlation with contact angle, suggesting that membrane hydrophilicity played an important role in membrane permeability. Finally, it was found that membranes with low ratios of PVDF/PES may have potential for water treatment applications, due to the combined advantageous properties of PES and PVDF.

RESUMEN

Os biorreatores com membrana (BRM) apresentam-se como um dos processos mais promissores para tratamento de águas residuárias com elevada carga orgânica, como os efluentes de laticínios, propiciando a geração de um efluente com elevada qualidade e adequado ao reuso direto ou após tratamento terciário. O objetivo desse trabalho foi avaliar o uso de BRM para tratamento de efluente de indústria de laticínios e utilizar a distribuição de massa molar da alimentação, do permeado e da fração solúvel do lodo como ferramenta para a investigação dos mecanismos de remoção dos poluentes no sistema. O BRM se mostrou um sistema viável para o tratamento do efluente em questão, apresentando eficiências de remoção de demanda química de oxigênio (DQO) e cor aparente de 98 e 99%, respectivamente. Através da distribuição de massa molar foi possível observar a alta capacidade de biodegradação e a estabilidade proporcionada pelo BRM, já que, mesmo em situações de alterações constantes nas características da alimentação, o líquido reacional sempre apresentou baixas concentrações de poluentes. Ressalta-se também a importância da membrana no sistema, uma vez que, além de permitir a retenção completa de biomassa e a operação com idades de lodo e concentração de sólidos suspensos maiores, pode proporcionar ainda a retenção de compostos que não foram biodegradados, contribuindo para a geração de um efluente tratado com alta qualidade.

The membrane bioreactor (MBR) is one of the most promising processes for the treatment of high organic load wastewaters, as dairy effluent, providing the generation of an effluent with high quality, which could be reuse directly or after tertiary treatment. The aim of this study was to evaluate a MBR to treat effluent from the dairy industry and to use molecular weight distribution of the feed, permeate and the soluble fraction of the sludge as a tool for investigating the mechanisms of pollutants removal in the system. The MBR has proven to be a viable system for the treatment of the effluent in question, with removal efficiencies of chemical oxidation demand (COD) and color of 98 and 99% respectively. Through the molar weight distribution it was possible to observe the high biodegradation capacity and stability provided by the MBR, as even in situations of constant change in feed characteristics, the mixed liquid always showed low concentrations of pollutants. It is also highlighted the importance of the membrane in the system, which, besides allowing the complete retention of biomass and operation with high solids retention time and suspended solids concentration, it can provide the retention of compounds which were not biodegraded, contributing to the generation a treated effluent with high quality.