As técnicas espectrofotométricas na região do UV-VIS, atualmente, são as principais formas indiretas de determinação dos parâmetros de matéria orgânica em corpos hídricos por apresentarem resultados satisfatórios. Nesse contexto, o presente estudo visa comparar alguns métodos que empregam as Absorbâncias únicas (UV230, UV235, UV250, UV254, UV270, UV275, UV280, UV285, UV365, UV465, UV665), tendo como proposta de trabalho a integração da área de absorbância nos espectros de onda de 230 a 290 nm (A230~290) em relação a carbono orgânico dissolvido (COD), demanda química de oxigênio filtrada (DQOf) e demanda bioquímica de oxigênio (DBO). Para tanto, as análises foram realizadas em três corpos hídricos com características distintas. A fim de verificar possíveis interações, foram determinadas as razões entre as absorbâncias nos comprimentos de onda; 250 e 365 nm (E2/E3), e para 465 e 665 nm (E4/E6), Absortividade Específica a 254 nm (SUVA254) e 285 (SUVA285). De acordo com os resultados (pUV280> UV270>UV250>UV254, para COD e UV235>UV270> UV280>UV254>UV250> UV275> UV285, para DQO. E não houve relações de caracterização possíveis para SUVA285, e E2/E3 e E4/E6, para possíveis interações e ou comparações. Além disso, de acordo com as condições e resultados apresentados, A230-290 demonstrou ser um parâmetro promissor (p<0,001) no sentido de atuar nas estimativas de concentração de COD (R=0,98547) e DQO (R=0,9203). Palavras-chave: UV-VIS. Matéria Orgânica. Qualidade de Água

Purpose: This study aims to evaluate the efficiency of electro-oxidation as a treatment option for textile effluents containing industrial dyes, with the goal of minimizing their environmental impact. Theoretical framework: The textile industry is known for its high water demand and generation of effluents containing dyes, posing an environmental challenge. Electro-oxidation is a promising technology for the degradation of pollutants that are difficult to mineralize. Method: The treatment process and operational conditions were described, utilizing a Boron-Doped Diamond (BDD) electrode. Three ranges of electric current (6, 12, and 18 mA cm-2) were tested to degrade the Procion Yellow (PY) dye. The removal of the dye, energy consumption, reduction in Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and effluent toxicity were evaluated. Results and conclusion: The treatment resulted in the removal of 91.4% of the dye, with an energy consumption of 88.4 kWh/m³ for a concentration of 150 mg/L of PY, following a first-order kinetics. Significant reductions in COD (74%) and TOC (85.2%) were observed. The effluent toxicity decreased at currents of 6 and 12 mA cm-2 but increased at 18 mA cm-2. Electro-oxidation proved to be a promising option for treating textile effluents containing industrial dyes. Research implications: The results contribute to the advancement of science and socio-environmental management practices in the textile industry, providing a viable option for effluent treatment and reduction of environmental impact. Originality/value: This study highlights the efficiency of electro-oxidation in the degradation of industrial dyes present in textile effluents, presenting relevant results on dye removal, energy consumption, COD and TOC reduction, as well as the evaluation of treated effluent toxicity.

Modelagem Hidrológica de larga escala com abordagem inercial/ Large scale Hydrological modeling with inerial approach

Objective: The objective of this study is to investigate the presence, abundance, and morphological characteristics of microplastics in the Cabaça Stream in Campo Grande-MS, seeking to understand their relationship with water quality and aiming at the preservation of aquatic ecosystems. Theoretical Framework: The research is based on studies regarding microplastic pollution, particularly in aquatic ecosystems. Two indices were utilized for the analysis of the water quality of the studied stream: the IQACETESB and the IQASmith (1987). The digestion and density separation methodology are based on Masura et al. (2015) and provided the foundation for the analysis of microplastics. Method: Water samples were collected using plankton nets to retain plastic particles. Microplastics were analyzed for abundance and morphology using an Olympus BX41 optical microscope with 40x zoom. The WPO method was employed for digestion and separation of the samples. Results and Discussion: The analysis revealed an abundance of 15,800 and 17,675 items/m³ in the 68 µm and 20 µm nets, respectively. Transparent fibers were the most frequent morphologies. The results highlight the relevance of the environmental issue and its potential risks to aquatic biota. Research Implications: The detection of microplastics in the Cabaça Stream indicates the need for public policies to mitigate the impacts of these pollutants on the environment. Originality/Value: This study contributes to expanding knowledge about the presence of microplastics in Brazilian ecosystems, employing a proven methodology for identification and quantification.

Objective: The objective of this study was to design a Water Quality Index (WQI) sensitive to the limits established by current legislation, focusing on the sustainable management of urban water bodies. Theoretical Framework: The research addresses the importance of regionalizing water quality indices to improve the monitoring of urban water management. Furthermore, it highlights that the indices used in urban streams lack good sensitivity to isolated parameter variations, which justifies the need for a new index. Method: The development of the new WQI consisted of four stages: parameter selection, normalization method, weight selection, and aggregation method. The initial parameters, such as total nitrogen, total solids, and temperature, were replaced by ammonia, nitrate, and surfactants. Normalization curves were also created, and the parameter weights were adjusted. Results and Discussion: The WQIBHU (IQABHU) demonstrated greater sensitivity to parameter variations compared to the WQICETESB (IQACETESB), with the exception of the ANH-01 point. Most of the quality values of the IQABHU were lower than those of the IQACETESB, indicating non-compliance with legal limits for urban stream classes. The IQABHU showed better performance in turbidity and dissolved oxygen (DO), while the IQACETESB masked the real water quality conditions, especially regarding the E. coli parameter. The new "±" tool allowed for more detailed monitoring of water quality, making the IQABHU more suitable for continuous monitoring and supporting decision-making by the competent authorities. Research Implications: The research has significant practical implications, as the proposed new WQI can be used as a tool to improve urban water management, contributing to the sustainability of water bodies and ensuring compliance with current environmental legislation. Originality/Value: The value and originality of this work lie in the proposal of a more sensitive index adapted to the reality of urban water bodies, using a systematic methodology for modifying and improving parameters and weights, which could represent an important advancement in water quality management.