Dissertação (MAASA)

Recondicionamento de membranas de osmose inversa: aplicação na osmose direta para rejeição de desreguladores endócrinos

Fri, 20 Feb 2026 00:00:00 GMT

Recondicionamento de membranas de osmose inversa: aplicação na osmose direta para rejeição de desreguladores endócrinos Cerqueira, Luciana Alencar Arcanjo, Gemima dos Santos The increasing water demand has driven the expansion of reverse osmosis (RO) desalination technologies on a global scale, which is associated with increased membrane disposal at the end of their useful life. At the same time, conventional wastewater treatment has limitations in the removal of endocrine disruptors (ED), which expose environmental and human health risks, and the forward osmosis process (FO) appears as a promising and low-cost technology to face these challenges. In this context, this research aimed to evaluate the reconditioning conditions of OI membranes for FO in the rejection of DE. The reconditioning took place via cleaning and chemical oxidation, and the membranes were evaluated in FO as to permeate flow (J) and solute inverse flow (Js), and physical-chemical characterization was performed by tests of hydraulic permeability, rejection, scanning electron microscopy, Infrared spectroscopy by Fourier transform, and zeta potential. The membrane determined as an optimal process was analyzed in the rejection of 17β-estradiol (E2) by estrogenic activity (RAE). In the preliminary tests, the desalination membrane with the best performance was exposed to KMnO4 at 250 ppm h, which reached J greater than 3,8 kg m⁻² h⁻¹, while the membranes from deionization systems presented more satisfactory results, with J greater than 7 kg m⁻² h⁻¹. In the definitive tests, the membrane reconditioned with NaClO at 10.000 ppm h showed better performance in FO with Js/J of 0,34 g kg-1, the lowest among those evaluated. Although the results of hydraulic permeability and rejection indicated better balance for the protocols with NaClO 5.000 ppm h and KMnO4 250 ppm h, the global analysis by means of membrane reconditioning index pointed to treatment with NaClO 10.000 ppm h as the most efficient, with a value of 0.96. This result indicates that the protocol removed incrustations and partially degraded the polyamide layer without compromising selectivity, being therefore selected as an optimal condition for the RAE analysis. The characterization suggests that the desalination membranes have severe and irreversible incrustations due to the cleaning and oxidation processes to which they were submitted, which was predicted in all FO tests. The membrane reconditioned with the optimal protocol was evaluated for E2 rejection, presenting a RAE greater than 99%, with a final concentration of 19,3 E2-Eq. ng L-1 in the osmotic solution. The membrane treated with KMnO4 250 ppm h also showed similar performance, with 19,75 E2-Eq. ng L-1 and 99,13% rejection. It is concluded that the reconditioning of OI membranes by chemical oxidation was effective for conversion and application in FO, with satisfactory performances and selectivity like new membranes. Universidade Federal da Bahia Dissertação

Potencial de Reaproveitamento do Concentrado da Osmose Inversa do Programa Água Doce – Bahia/Brasil Como Solução Osmótica no Processo de Osmose Direta

Wed, 16 Dec 0016 00:00:00 GMT

Potencial de Reaproveitamento do Concentrado da Osmose Inversa do Programa Água Doce – Bahia/Brasil Como Solução Osmótica no Processo de Osmose Direta Araújo, Woshington Luiz de Arcanjo, Gemima Santos The Programa Água Doce (PAD) aims to ensure permanent and sustainable access to high-quality drinking water through desalination systems that employ Reverse Osmosis (RO) technology. This technology, however, generates reverse osmosis concentrate (ROC), a potentially polluting by-product. The present study adopted a quantitative methodological approach based on experimental investigation using primary data. The general objective was to evaluate the potential reuse of ROC generated by RO desalination units of the Água Doce Program (PAD) in Bahia, Brazil, as a draw solution in a Forward Osmosis (FO) system. Specifically, the study sought to: (i) assess pollutant removal through the FO process using ROC as the draw solution; (ii) optimize FO system operation under conditions where ROC is used as the draw solution; and (iii) investigate the salinity profile of the draw solution resulting from FO system operation and its potential reuse. The results showed that, after ROC characterization and during 264 hours of operation, the permeate flux progressively decreased, reaching an average value of 2.7 L/m²·h. The reverse salt flux remained relatively constant, although some peaks outside the linear trend were observed, with an average of 6.3 g/m²·h. The average conductivity decreased from 27.67 mS/cm to 15.92 mS/cm. Scanning Electron Microscopy (SEM) analyses revealed that the new membrane exhibited a uniform and unaltered morphology, with no evidence of fouling. In contrast, the used membrane showed precipitated salt deposits on its surface, which led to a reduction in water flux from 3.89 L/m²·h to 2.83 L/m²·h. Experiments performed with methylene blue (MB) dye showed a 98% rejection rate, demonstrating the efficiency of the Forward Osmosis (FO) process. It can be concluded that the use of ROC as a draw solution (DS) is feasible and advantageous, particularly when diluted and reused from concentrates generated in RO desalination systems. Universidade Federal da Bahia Dissertação

Avaliação de limiares críticos de inundação para implementação de sistema de alerta em região urbana com monitoramento hidrológico limitado e interação fluvial

Fri, 04 Jul 2025 00:00:00 GMT

Avaliação de limiares críticos de inundação para implementação de sistema de alerta em região urbana com monitoramento hidrológico limitado e interação fluvial Farias, Pedro Rocha Fontes, Andréa Sousa The study aimed to define critical rainfall and hydraulic thresholds to support a flood warning system in Itabuna, Bahia, an urban region with limited hydrological monitoring. To achieve this, hydrological and hydrodynamic modeling was used to simulate flood events under different rainfall scenarios. Rainfall data, from a grid, and flow data, obtained from a fluviometer, applied for model calibration, underwent a prior consistency analysis. It was found that the grid rainfall was representative for the study area based on the applied statistical metrics. However, the flow data showed discontinuity and overestimation, compromising the accuracy for modeling. The applied hydrological model was satisfactorily calibrated for two flood events in the study area, with one of the calibrations chosen for the continuation of the study. With the calibrated hydrological model, ten hydrographs were generated, corresponding to ten different accumulated rainfall amounts, which were propagated in the hydrodynamic model, resulting in flood scenarios for the municipality. The methodology enabled the identification of accumulated rainfall amounts that led to the exceedance of alert levels, associated with peak flows in different monitored sections. In the most intense event, all alert thresholds in the areas of interest were exceeded. Maps representing the extent of floods and wave propagation time demonstrated the evolution and severity of the events, indicating a significant increase in the affected area in proportion to the rainfall intensity. Additionally, maps of body instability risk (such as overturning and slipping) revealed dangerous situations in areas near watercourses from a certain level of event severity, with the expansion of higher-risk zones. This work highlights the feasibility of a methodology to analyze and correlate accumulated rainfall with hydraulic parameters in locations with limited hydrological monitoring capacity. Such an approach can contribute to the development of flood preparedness and response plans in municipalities with restricted monitoring infrastructure, offering support to civil defense agencies in defining alert levels and communicating risks to the population. UNIVERSIDADE FEDERAL DA BAHIA Dissertação

Tratamento de lodo de reator UASB em leitos plantados com Cyperus papyrus

Mon, 28 Jul 2025 00:00:00 GMT

Tratamento de lodo de reator UASB em leitos plantados com Cyperus papyrus Queiroz, Alex Sandro Ferreira de Nascimento, Francisco Ramon Alves do When seeking the use of sewage sludge generated in treatment plants, it is necessary for this material to undergo processes that reduce the content of biodegradable organic matter, the concentration of pathogenic microorganisms, and the moisture content, in order to obtain a product that does not pose a risk to human health and is primarily dry, facilitating transportation and handling. The objective of this study was to evaluate the treatment of sludge from UASB reactors in Planted Drying Beds (PDB) systems, characterizing the physicochemical and microbiological parameters of this sludge after treatment. Three vertical flow PDB planted with Cyperus papyrus were constructed and subsequently monitored for 6 months. The loadings applied were approximately 6, 7, and 8 kgTS/m²week, corresponding to 255, 304, and 363 kgTS/m²year for Leach Bed 01, Leach Bed 02, and Leach Bed 03, respectively. The results demonstrated the effectiveness of CWs in reducing the sludge volume, showing a 79% reduction in the loaded sludge, with total solids content ≥ 65% and volatile solids/total solids ratios below 0.39 (VS/TS ≤ 0.39) for all three leach beds at the end of the resting period. After three months of resting, the biosolid also presented low pathogen concentration (E. coli < 4.00E-1 MPN/gST). Leach Bed 01, Leach Bed 02, and Leach Bed 03 presented nitrogen dry mass contents of 11.8%, 13%, and 12.7%; phosphorus contents of 0.05%, 0.03%, and 0.13%; and potassium contents of 0.5%, 0.63%, and 0.36%, respectively. The metals analyzed showed values well below the limit established by CONAMA Resolution No. 498/20, where for Cd, for example, the obtained value was 96% below the established limit. According to CONAMA Resolution No. 498 of 2020, the parameters obtained from the generated biosolids allow their classification as Class A. Universidade Federal da Bahia Dissertação