http://repositorio.ufc.br/handle/riufc/460 Wed, 10 Jun 2026 12:03:14 GMT 2026-06-10T12:03:14Z http://repositorio.ufc.br/handle/riufc/86649 Título: Enhancement of anaerobic azo dye decolorization under saline and sulfate-rich conditions through electron transfer-based strategies Autor(es): Oliveira Júnior, José Kleber Sousa Abstract: Azo dyes are among the most persistent pollutants in textile wastewaters due to the high stability of their aromatic structures and resistance to conventional biological treatment processes. Reactive Black 5 (RB5), one of the most widely used azo dyes, represents a significant environmental challenge when present in industrial effluents. In this context, this doctoral thesis investigated strategies to intensify the anaerobic decolorization of RB5 under conditions representative of real textile wastewaters, with emphasis on modulating extracellular electron transfer through the use of soluble and insoluble redox mediators and iron-based additives. Batch experiments, with 10h of duration, confirmed that RB5 decolorization occurs predominantly via biological reduction, with abiotic controls showing removals below 5%. The addition of the soluble redox mediator anthraquinone-2-sulfonate (AQS) increased decolorization efficiency from approximately 70% to up to 87% and enhanced the first-order kinetic constant from 0.19 to 0.33 h-1 . Sulfate exerted a limited effect on decolorization (~72- 73%), whereas salinity caused moderate kinetic inhibition. The combined presence of chloride and sulfate constituted the most restrictive condition, reducing RB5 removal to approximately 65-68% and the kinetic constant to 0.15-0.17 h-1 ; nevertheless, AQS maintained a positive effect under all tested scenarios. In continuous anaerobic reactors, RB5 decolorization under control conditions typically ranged from 66 to 75% and decreased to approximately 60-68% in the presence of sulfate due to competition for reducing equivalents. Salinity had a more pronounced impact on organic matter removal, decreasing COD removal to approximately 35-40%, while exerting a comparatively smaller effect on dye decolorization. AQS addition consistently improved RB5 removal by about 5-7%, although at the expense of COD removal. Recovery tests demonstrated rapid restoration of dye decolorization, whereas COD removal exhibited partial and slower recovery, indicating greater resilience of dye-reducing pathways compared to methanogenic processes. The evaluation of iron-based materials revealed strong speciation- dependent effects. Zero-valent iron (Fe0 ) emerged as the most effective additive, increasing RB5 removal to approximately 80-82% in continuous reactors and raising the kinetic constant to up to 0.24 h-1 in batch assays, while providing high operational stability even under reduced hydraulic retention time. Magnetite and soluble iron species (Fe2+/Fe3+) produced more moderate improvements (~69-77%), strongly dependent on dosage and bioavailability. In addition, insoluble carbonaceous materials, such as activated carbon and biochar, particularly when functionalized with AQS, enabled RB5 removals above 80% and promoted enrichment of electroactive microbial consortia. Overall, this thesis demonstrates that intensification of anaerobic azo dye decolorization in complex textile wastewaters can be achieved through targeted modulation of extracellular electron transfer, resulting in significant gains in efficiency, kinetics, and operational robustness. These findings provide scientific and technological foundations for the development of more efficient and resilient anaerobic treatment systems applicable to real textile effluents. Tipo: Tese Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86649 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86632 Título: Utilização de ensaios de campo para a avaliação da resistência mecânica de um aterro sanitário de resíduos sólidos urbanos (RSU) Autor(es): Silva, Roberto Antonio Cordeiro da; Moura, Alfran Sampaio; Carneiro, Andressa de Araújo; Pinheiro, Claver Giovanni; Vasconcelos, Sônia Maria Silva Abstract: In this study, was evaluated the geomechanical behavior of the municipal solid waste (MSW) of the Metropolitan Sanitation Landfill of Caucaia (ASMOC), with emphasis on shear strength. Laboratory tests for the physical characterization of MSW, Standard Penetration Tests (SPT) and plate load test (PLT) were carried out in different time points, in an Experimental Cell and in the old existing landfill. Subsequently, based on the results of the PLT, the bearing capacity of the experimental cell and the old landfill was determined. The SPT did not reveal any tendency to increase or decrease in the penetration resistance index (NSPT) over time. The PLT showed a linear relationship between the applied pressure and the settling obtained with the plate was evident, in the experimental cell and in the old landfill, indicating the absence of the physical rupture in the mass of the requested waste. The effect of the fiber in the waste behavior could only be observed in the old landfill. In general, the old landfill had higher stiffness and bearing capacity than the experimental cell. Tipo: Artigo de Periódico Fri, 01 Jan 2021 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86632 2021-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86631 Título: Settlement’s Prediction of Piles in Tropical Soil Autor(es): Bezerra, P. H. L.; Moura, A. S.; Silva Filho, F. C.; G. Filho, F. V. C.; Cerqueira Junior, E. Abstract: The prediction of deep foundation settlements remains challenging due to the scarcityofstudies about it. This paper aimed to evaluate the accuracy of the usage of load transfer methods in predicting the settlement of bored piles in granular soil in Brazil’s Northeast. For this, two small piles were installed and submitted to load tests, a small amount of expansive polystyrene was placed under one of the pile’s tips to evaluate the load distribuition of the elements.. For the settlement’s prediction, methods based on load transfer functions, such as analytical and numerical (using RSPile and UniPile ), were employed. The comparinson of the predicted values with the experimental measurements showed agreement in the elastic zone of soil’s behavior for all the methods. For higher loads, discrepancies occurred. The method proposed by Massad (1992) was the most effective among the used methodologies. Using the mentioned programs, results were close to the experimental values. Tipo: Artigo de Periódico Fri, 01 Jan 2021 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86631 2021-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86630 Título: Avaliação do efeito da eficiência das sondagens à percussão na previsão de capacidade de carga e recalque de estacas pré-moldadas Autor(es): Rodriguez, Yan Carlos Chiu; Moura, Alfran Sampaio; Silva, Danton França da; Cavalcante, Lucas Pereira Abstract: In building projects, foundations must meet project requirements to ensure the safety of the work. Therefore, estimates of load capacity and foundation settlements are necessary. It is usual to make these estimates based on the results of field trials. The present work proposes an evaluation of the predictions of load capacity and settlements of foundations on precast piles using semi-empirical and theoretical methods based on the results of percussion sounding (SPT), with and without consideration of the test efficiency correction. To this end, seven piles were analyzed, manufactured in reinforced concrete, and driven into typical soil profiles of the Metropolitan Region of Fortaleza (RMF). For the proposed evaluation, the results of load tests and SPT surveys were used. The predictions estimated by semi-empirical and theoretical methods were compared to the values obtained experimentally through load tests. The load capacity and settlement predictions were made without correcting the sounding efficiency and for an efficiency of 70%. Considering the correction of the efficiency of SPT soundings, both in load capacity and settlement calculations, promoted more consistent predictions for almost all situations analyzed. Tipo: Artigo de Periódico Sun, 01 Jan 2023 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86630 2023-01-01T00:00:00Z