http://repositorio.ufc.br/handle/riufc/497 Fri, 15 May 2026 15:29:50 GMT 2026-05-15T15:29:50Z http://repositorio.ufc.br/handle/riufc/86193 Título: Substituição gradativa de sacarose pela fração líquida de resíduos de frutas e verduras em reator anaeróbio de leito fluidificado Autor(es): Dias, Ulisses Vitório Abstract: Proper management of fruit and vegetable waste (FVW) generated in Food Supply Centers (Ceasa) is an environmental and economic challenge. Dark fermentation (DF) emerges as a promising alternative for the valorization of these wastes, converting them into bio-hydrogen and organic acids (FAs). Among the reactors used, the anaerobic fluidized bed reactor (AFBR) stands out for its high biomass retention rate and capacity to support high organic loads. However, the literature lacks systematic studies on the adaptation and stability of AFBRs operating with complex substrates such as the liquid fraction of fruit and vegetable waste (LFVW). Given this, this dissertation evaluated the performance of a hydrocarbon-based reactor (RALF) in hydrogen production, subjected to a progressive increase in the concentration of volatile fatty acids (VFA) (0 to 100%) in the substrate, replacing sucrose, under mesophilic conditions (30 °C), with a hydraulic retention time (HRT) of 2 h, and a constant volumetric organic loading rate (LOR) of 60 kg COD m reactor -3 d -1 , without pH control. Under the 100% sucrose condition, the volumetric hydrogen production (HVP) and yield (YH) were 4361 mL H2 L reactor -1 d -1 and 2.6 mmol H2 g -1 COD applied, respectively. With complete replacement by VFA (100%), a sharp decline was observed, with HVP and YH reaching only 261 mL H2 L reactor -1 d -1 and 0.2 mmol H2 g -1 COD applied. This decrease was associated with a change in the metabolic profile of the microbial community, with an accumulation of propionic acid (APr) coupled with a consistently acidic pH (range of 4.0 and 4.3), which suppressed H2 producing bacteria and diverted carbon flow to acidogenic H2-consuming pathways such as propionogenesis and homoacetogenesis. However, integrated analysis with literature data demonstrated that the complex nature of FLRFV is not an absolute limiting factor. Operating the RALF with shorter HRTs (1 h) and higher VOCs (240 kg COD m reactor -3 d - 1 ) proved to be an effective strategy to reverse this scenario, establishing a butyric metabolic pathway and increasing PVH by up to 35 times. Therefore, the viability of FLRFV for bio-hydrogen production is intrinsically linked to an optimal operating window of HRT/VOC, which exerts selective pressure favorable to hydrogenogenic bacteria, overcoming the initial complexity of the residue. Tipo: Dissertação Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86193 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86192 Título: Análise de suscetibilidade à liquefação dinâmica de areias com diferentes teores carbonáticos do litoral cearense mediante ensaios triaxiais cíclicos Autor(es): Cavalcante, Lucas Pereira Abstract: This study aims to investigate and evaluate the dynamic behavior and liquefaction susceptibility of soil samples with varying carbonate contents. This research is part of a larger project funded by Petrobras in partnership with the Federal University of Ceará. For this purpose, sandy samples were collected from different locations along the coastal zone of Ceará, exhibiting distinct carbonate contents in their compositions. These samples were obtained both from beach zones and from the offshore continental shelf. The selected sampling sites were Barra do Ceará Beach in Fortaleza, Moitas Beach in the county of Amontada, and Icapuí Beach in the county of same name. The samples were submitted characterization and calcimetric tests for classification purposes. Subsequently, a series of cyclic triaxial tests under strain-controlled conditions was performed. For the cyclic tests, the samples were sieved through a 2.38 mm mesh, in accordance with standard requirements and to ensure compatibility of results with the ongoing research. The samples were designated as follows: Barra do Ceará (BC 4), Moitas (MT 3), Icapuí (ICAP 5), and Offshore Platform (PCO 3). Based on their measured carbonate contents, they were classified respectively as lithoclastic (9.17%), lithobioclastic (40.70%), bioclastic (85.98%), and bioclastic (92.03%). The cyclic loading frequency adopted for all tests was 1.0 Hz, with strain amplitudes of 0.1%, 0.3%, 0.5%, and 0.7%. The confining pressure applied in all tests was 50 kPa, and all specimens were prepared at a relative density corresponding to a loose condition. The analyses considered the following parameters and plots: deviator stress, stress–strain behavior, pore pressure ratio, stress path, cyclic resistance, and stiffness degradation. The results indicated that samples with higher carbonate contents – particularly ICAP 5 – exhibited plots, behaviors, and cyclic resistance relatively superior to those of the predominantly quartzose sample (BC 4). In conclusion, it was observed that samples with higher carbonate contents tend to present greater cyclic resistance and lower stiffness degradation, likely associated with their carbonate composition. Furthermore, it was verified that bioclastic samples are capable of developing cyclic resistance exceeding 100% in certain cases, as evidenced by the mobilized deviator stress and the number of cycles required for liquefaction to occur. Tipo: Dissertação Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86192 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86106 Título: Study of emerging aerobic biotechnologies for sewage treatment and resource recovery Autor(es): Ferreira, Tasso Jorge Tavares Abstract: Activated sludge (AS) technology is the most used in sewage treatment plants (STPs) worldwide. However, with the population growth of recent decades, industrial advances, and changes in consumption patterns, the generation and complexity of effluents have also increased. Thus, STPs face the challenge of increasing treatment efficiency, often to comply with legal requirements for water bodies discharge increasingly restrictive. The search for improvements resulted in the emergence of new technologies such as MBBR (Moving Bed Biofilm Reactor), IFAS (Integrated Fixed FilmActivated Sludge), and AGS (Aerobic Granular Sludge). Therefore, this study was carried out to compare the above emerging aerobic technologies in sanitary sewage treatment to contribute to decision-making in designing future ETEs. In addition, several ways of recovering resources were pointed out to assist in introducing the circular economy within sewage treatment. The first investigation evaluated the influence of including a biofilter layer in a sequential batch reactor with AGS. This study observed that theAGS-BF (R2) system provided a high-quality effluent in terms of total suspended solids and turbidity, in addition to obtaining Total Nitrogen removals above 80% throughout the experimental period. Another fact observed was that the sludge production was evaluated, and the yield coefficient (Y, gVSS/gCODrem) and sludge concentration were higher in the AGS-BF reactor than in the conventional AGS reactor. The new reactor configuration proved to be an alternative to improve some aspects of conventional AGS reactors, such as denitrification and nitrite accumulation, the concentration of TSS in the effluent, and increased system reliability during periods of instability and granule breakage. The second investigation compared four emerging aerobic technologies (MBBR - R1, IFAS - R2, AGS - R3, and AGS-BF - R4) for sanitary sewage treatment and resource recovery. In this study, COD removal and nitrification were high for all reactors. However, total nitrogen removal was moderate for reactors R1 (48%) and R2 (54%), but values above 70% were observed for R3 and R4. Phosphorous removal was also possible, reaching values below 52% for the MBBR (R1) and IFAS (R2) systems but with values above 80% in the aerobic granulation systems R3 and R4. The concentration of volatile solids in the effluent was also higher in R1 and R2 (6.1 and 6.7 mg/L, respectively) when compared to R3 (4.2 mg/L) and R4 (5.4 mg/L). The third study consisted of a systematic review of the recovery of resources such as water, energy, chemicals, raw materials, and nutrients in AGS systems. In this study, several ways of recovering resources were shown, such as water reuse, the use of sludge as inoculum in AGS WWTPs, recovery of phosphorus, recovery of alginate, tryptophan, polyhydroxyalkanoates, biogas, and other compounds found in AGS. Finally, this study highlighted that the recovery of resources inAGS systems could be a solution to reduce treatment costs, making the technology more viable and decentralized. Tipo: Dissertação Sun, 01 Jan 2023 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86106 2023-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86080 Título: Utilização do pressiômetro de Ménard no estudo das areias carbonáticas do litoral Cearense Autor(es): Nascimento, Matheus Vasconcelos do Abstract: This research investigates the stress-strain behavior of carbonate sands subjected to the Ménard pressuremeter test, aiming to determine representative geotechnical parameters for these atypical soils. The research was developed on marine sands with different carbonate contents, typical of coastal environments in Northeast Brazil, whose structure and cementation influence the mechanical response of the soil. The study is situated within the context of the expansion of offshore wind energy in the country, seeking to provide technical support for the safe and economical design of foundations on carbonate sandy soils. Ménard pressuremeter tests were carried out on the beaches of Moitas, in Amontada/CE, and on the beaches of Caiçara, Redonda and Retiro Grande, in Icapuí/CE. These tests allowed for the determination of deformability parameters (EM, E, G) and resistance parameters (σh0, Pf, Pl e φ’). The variation of these parameters with depth and carbonate content in the samples was analyzed to understand a possible influence of mineralogical composition on the stress-strain response of the soils. The parameters obtained were applied to estimate the bearing capacity and settlements of an offshore gravity wind turbine foundation, based on established analytical methodologies and comparisons with predictions derived from SPT soundings. The results preliminarily indicated that increasing the carbonate content tends to increase the initial stiffness and ultimate strength, reflecting in higher values of pressuremeter modulus and ultimate pressure. The bearing capacity predictions based on the pressuremeter test were, on average, lower than those obtained by SPT, highlighting the obtaining of more conservative predictions when using PMT tests on the investigated carbonate sands. It is concluded that the Ménard Pressuremeter is an effective tool in evaluating the deformability and strength of carbonate sands, especially for the design of offshore gravity foundations. Given the specific conditions of the region studied, this type of foundation proves to be technically viable for the installation of wind turbines. The study not only expands knowledge about the behavior of these soils, but also confirms the relevance of disseminating pressuremeter testing in regional and national geotechnical scenarios. Tipo: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86080 2026-01-01T00:00:00Z