Recuperação de recursos de biomassa algácea cultivada com esgoto sanitário através de pré-tratamento hidrolítico para produção de biogás e carbonização da biomassa residual

• Autor(a) principal: Estevam, Renata
• Data de Publicação: 2024
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/17360
• topic: Área(s) do conhecimento do documento (Tabela CNPq); Biomassa Algácea; pré-tratamento; biometano; carvão ativado; adsorção; esgoto sanitário; subject.br-rjbn

This research aimed to address gaps in the sustainable valorization of algal biomass from wastewater, providing insights and innovative strategies to boost its reuse and promote sustainable development. The core objectives encompassed optimizing the reuse of algal biomass harvested from high-rate ponds, considering the presence and absence of coagulants, both organic and inorganic. The research assessed the influence of these coagulants and thermal and thermochemical pre-treatments at various stages, from biomass harvesting to the production of biogas, activated carbons, and tests for toxic dye adsorption—a critical issue for efficient wastewater disinfection. An innovative approach was adopted for algal biomass harvesting, involving an experimental pilot that enabled total solids content exceeding 2%, without the need for energy-intensive equipment. Pre-treatments were conducted under different experimental conditions, and operational parameters were obtained through a second-degree polynomial, a response surface methodology (RSM) providing high reliability to the results. Data collection involved laboratory physicochemical analyses, elemental analysis (CHNS-O), Fouriertransform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA and DrTGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Statistical methods were applied to interpret the results, ensuring the reliability of conclusions and scalability. Results indicated that specific pre-treatments, such as 78°C for 7 hours in pure biomass, 80°C for 1.5 hours at pH 1 in Tanfloc-treated biomass, and 90°C for 3 hours at pH 11 in biomass treated with aluminum sulfate, provided efficiency in soluble COD solubilization, solid reduction, and nutrient solubilization, demonstrating the feasibility of optimized reuse from hydrolysis residues. Pre-treated biomass used in anaerobic digestion, especially algal biomass pre-treated at 90°C for 3 hours at pH 11, showed remarkable results, indicating no microbial inhibition by aluminum salts and viability for implementation in integrated systems targeting biogas production. In the context of reuse pathways, pre-treated biomass used as a precursor material in activated carbon production achieved significantly higher specific surface areas compared to untreated algal biomass. Changes in FTIR spectra indicated beneficial modifications in the composition of activated carbons produced from pretreated biomass, particularly an increase in the thermostability of activated carbons derived from pre-treated biomass, reflecting a decrease in recalcitrant compounds in the biomass. These results provided valuable insights for optimizing activated carbons in adsorption processes. Physical and chemical characteristics resulting from synergistic effects among pre-treatments, carbonization, and activation significantly contributed to conducting toxic dye adsorption tests, revealing the potential of these activated carbons as effective adsorbents for removing persistent toxic dyes in wastewater at low concentrations, indicating their viability for future modeling and applications of activated carbons in the integrated context of microalgae biorefineries. The research goes beyond a mere understanding of processes, significantly contributing to science. Key highlights include identifying new routes for waste reuse, optimizing biogas production, understanding the effects of pre-treatments on activated carbons and coagulants, both organic and inorganic and applying these materials to remove toxic dyes.