This study presents an analysis of the abrasive effects of sediments from the bed of the Acre River, Brazil, on the wear of three different ferrous materials employed in the manufacture of impellers of centrifuge pumps used to catch raw water. In order to evaluate the abrasive wear and specific wear coefficient (k) as a function of sediment concentration, tests were conducted in samples of SAE 8620 steel, nodular cast iron and gray cast iron by using a rotary-ball abrasion meter. These tests employed abrasive slurry with concentration of 1, 2, 3, 5 and 10 g L^-1 of sediments in distilled water. The volume of worn material as a function of the relative velocity of water flow in relation to the impeller blades was mathematically estimated. The experimental results showed that: i) The semi-angular and semi-rounded shapes of the sediments from the Acre River produced evidence of micro-grooving and plastic deformation in the three metallic alloys; ii) SAE 8620 steel showed higher resistance to abrasive wear than samples of gray and nodular cast iron; iii) the increase in the volume of worn material due to increment in sediment concentration and the relative velocity of the mixture (water + sediment) to the rotor pads.

Constructed wetlands are nature-based technologies widely used for the treatment of wastewater and contaminated surface water. This study evaluated the efficiency of free water surface (FWS) and horizontal subsurface flow (HSSF) constructed wetlands in reducing the turbidity of mine spoil rainwater using the w-C* model. Different hydraulic retention times (2, 4, and 6 days) were tested, and the influence of macrophyte type and substrate on the w parameter was investigated. Model calibration was performed based on correlation coefficients (R), coefficient of determination (R²), Nash–Sutcliffe efficiency (NSE), and root mean square error (RMSE). The results indicated a 99% reduction in turbidity, with average values of R = 0.87 ± 0.05 (FWS) and 0.87 ± 0.03 (HSSF), and NSE of 0.76 ± 0.04 (FWS) and 0.74 ± 0.07 (HSSF), demonstrating good agreement between observed and predicted data. The settling rate (w) ranged from 0.16 to 0.40 m·d⁻¹ in FWS and from 0.20 to 0.70 m·d⁻¹ in HSSF, with the lowest value recorded in the control (0.09 m·d⁻¹). The best performances were observed in FWS-P with Pistia stratiotes (0.40 m·d⁻¹) and HSSF with Typha domingensis (0.70 m·d⁻¹), demonstrating that vegetation, combined with the use of medium-grain substrate (9.5–19.0 mm), enhances turbidity removal. The w-C* model proved to be a robust tool for describing the kinetics of suspended colloidal particle removal in constructed wetlands, providing valuable insights for optimizing hydraulic parameters and design criteria for full-scale application.

Objetivo: Analisar o Plano Municipal de Saneamento (PMSB) do município de Ouro Preto, buscando sugerir seu aperfeiçoamento diante de eventuais lacunas identificadas. Teórico referencial: A Lei n. 14.026 (2020), que atualiza o marco legal do saneamento básico, estabelece diretrizes nacionais para o setor, cita a elaboração do Plano Municipal de Saneamento Básico (PMSB) como instrumento de planejamento. Método: O processo metodológico procedeu-se em duas etapas, sendo, respectivamente, de caráter exploratório e qualitativo, dados por estudo documental e análise por meio da lista de verificação (checklist ) . Essas listas de verificação são constituídas por um conjunto de categorias, divididas em subcategorias, das quais foram analisadas os componentes do saneamento, assim como os princípios fundamentais. Resultados e Conclusão: O levantamento dos checklists possibilitou constatar as seguintes lacunas no Plano, a saber: Políticas como combate à pobreza e sua erradicação; política e plano de prevenção de riscos e desastres, e política de gênero e promoção da igualdade. Conclui-se que o PMSB do município de Ouro Preto necessita de maiores investimentos quanto aos componentes do saneamento, sobretudo o de orientação, associando-se aos princípios fundamentais, de modo a contribuir sobretudo com a universalização dos serviços. Implicações da Pesquisa: O estudo indica lacunas da legislação frente ao PMSB de Ouro Preto, sendo uma base para futuras versões. Originalidade/valor: A pesquisa é dada como um estudo de caso onde os princípios fundamentais indicados na Lei n.14.026 (2020), que é recente, são avaliados. É fundamental que as cidades sejam comprovadas quanto a seus instrumentos urbanos sob essa ótica.

This study investigated nutrient removal in tubular photobioreactors (PBR) illuminated by Light-Emitting Diodes (LEDs), treating the effluent from an Up-Flow Anaerobic Sludge Blanket (UASB) system followed by a Biological Percolator Filter (BPF). Designed as a tertiary treatment step, the PBRs aimed to minimize eutrophication while promoting microalgal growth through CO₂ assimilation released by bacterial activity—resulting in biomass with potential for value-added applications. The objective of this study was to elucidate the mechanisms responsible for nitrogen and phosphorus removal under a controlled environment. A key novelty of this work lies in the comparative evaluation of red and blue LED illumination in the pilot-scale PBRs used for wastewater treatment. All systems achieved >99% ammoniacal nitrogen removal, while soluble phosphorus removal achieved up to 95%. The highest nitrogen removal rate was observed under red light (10.60 mg L⁻¹ d⁻¹), although there was no difference for blue light, while blue light was more effective for phosphorus removal (3.28 mg L⁻¹ d⁻¹). Assimilation was the primary removal mechanism, supported by microalgae–bacteria interactions and artificial CO₂ injection. The research highlights distinct advantages of each light illumination: the blue-light photobioreactor was more suitable for tertiary treatment, whereas the red-light system showed potential for microalgal biomass-based co-product generation.

This research aimed to apply a risk management methodology to multiple surface water sources in urban and rural areas of a developing country. The applied methodology enabled the identification of hazards, classification, and the prioritization of risks at 21 collection points in the rural area and 9 collection points in the urban area. Both rural and urban areas exhibited common events with a high-risk level, such as human access (100% in urban areas and 90% in rural areas), climatic events, and inadequate collection structures (100% of points in both urban and rural areas). However, rural areas presented specific risks associated with animal husbandry (70% of points with high risk), a lack of monitoring, limited infrastructure (30% of points with high risk), and wildlife, including birds and worms (50% of points with high risk in rural areas and 10% in urban points). On the other hand, urban areas faced challenges related to vandalism and sabotage (high risk in 40% of points). Understanding these similarities and differences permits integrated risk management among the various stakeholders who can contribute to risk management within a watershed.

The abrasion resistance of the impellers depends on the characteristics of the materials used in their manufacture. In this work, a methodology is proposed for the evaluation of the abrasive wear of the plates of the centrifugal pump impellers, used in the gross water infrastructure station (GWIS) of sedimentary rivers, due to the sediment load variation and the river fluviometric dimension. In order to determine the wear mode and the relationship of the material-specific wear coefficient (K), due to the sediment concentration, a rotating ball abrasometer test was performed on SAE 8620, gray cast iron (GCI), and nodular cast iron (NCI), used in the manufacture of impellers. As an abrasive suspension, the concentrations of 1, 2, 3, 5, and 10 g L−1 of sediment were used in distilled water. The wear volume as a function of the relative velocity of the mixture in relation to the impeller blades was estimated mathematically. The results show that: i) The abrasive capacity of the sediments in different concentrations; ii) SAE 8620 steel was more resistant to abrasive wear; and iii) the rotational control of the pump as a function of sediment concentration and river level showed the possibility of reducing wear by 30%.