Ambiente e Agua - An Interdisciplinary Journal of Applied Science

Water usage in Brazil's industrial sector: estimated withdrawal, consumption, and discharge by the 30 largest industries in the country

Ana Lúcia Eufrázio Romão — 2026-01-24

This study evaluated the water intake, consumption, and disposal by the 30 largest industries in Brazil, based on water consumption coefficients developed by the Agência Nacional de Águas e Saneamento Básico (ANA), technical coefficients developed by the Confederação Nacional da Indústria (CNI), and considering Brazilian annual production based on coefficients from the literature. The collected data show that, according to the volumes available in the Planilha de Outorgas, licenses were granted for the intake of 741.47 ML and for the disposal of 515.8 ML of water for the period between 2021 and 2023, considering only the companies listed in this study that requested licenses from ANA. According to the data disclosed by the companies, the intake volumes are 465,733.441 ML and the disposal volumes are 136,067.19 ML (considering only the companies that disclosed their consumption). It was not possible to establish a direct correlation between the coefficient estimates based on declared production (CNI) and those related to the number of jobs (ANA). Therefore, estimating water use using technical coefficients may be more effective by accessing data obtained directly from the industry targeted by the study or through government water resource management agencies, and for better water resource management in the country, greater transparency in data disclosure is needed, both by companies and the government.

Keywords: effluent, technical coefficients, water permits, water scarcity.

Morpho-functional groups of periphytic algae from rivers of La Planada Reserve and their bioindicator role

Mayra Camila Guerrero-Lizarazo — 2026-01-24

Freshwater periphytic algae play a vital ecological role in aquatic ecosystems. In this study, we examined the morphological features of periphytic algae in four rivers of the La Planada Reserve. We collected samples by scraping rocks, identified the algae, measured their morphological dimensions, and conducted descriptive and multivariate statistical analyses. We identified 59 morphospecies, mainly belonging to the classes Bacillariophyceae and Cyanophyceae. The functional groups identified included mucilage-forming colonies, simple filaments, hetero-filamentous algae, non-specialized algae, and non-flagellated siliceous algae. The community-weighted mean and variance (CWM and CWV, respectively) of morphological variables did not differ significantly between rivers. In the first-order river, the algae tended to be smaller and had a lower surface-to-volume ratio. Simple filamentous algae and small algae lacking specialized features seem to indicate nutrient-deficient waters. Non-flagellated, silica-shelled algae (diatoms) probably serve as indicators of moderate flow rates, higher nutrient levels, and clearer water. Colonial algae with mucilage tend to prefer waters with moderate to high nutrient concentrations and faster current speeds. Hetero-filamentous algae appear to indicate rivers with low light exposure and slow flow velocity. This initial investigation into the morpho-functional study of periphytic algae suggests that morphology-based groupings could help reflect river environmental conditions through the ecological responses of functional algal associations.

Keywords: biogeographic Chocó, functional ecology, phycoperiphyton.

Evaluation of the efficiency of excavated structures for sediment containment at the Sapo Mine in Conceição Do Mato Dentro, Santo Antônio River basin, Minas Gerais

José Augusto Costa Gonçalves — 2026-01-24

Given the challenges posed by water erosion and sediment transport associated with mining activities, it is essential to give due importance to sediment containment, as sediments are potential generators of environmental impacts in river basins and associated socio-environmental conflicts. This study evaluated the use of excavated structures for sediment containment and the effective implementation of the 2024 Rainfall Plan at the Sapo Mine, owned by Anglo American, located in the Santo Antônio River basin, in the municipality of Conceição do Mato Dentro, Minas Gerais. The main objective was to evaluate the plan's effectiveness in containing sediments, protecting the basin's water bodies, and ensuring the continuity of mining operations. Data acquisition was carried out through bibliographic surveys, analysis of meteorological and hydrological data, local assessments, topographic, bathymetric, and water quality monitoring, using drones and specific software for spatial and volumetric analysis of sediments. The results showed that the implemented structures contributed significantly to the reduction of turbidity and sediment retention during intense rainfall events. The measured sedimentation rate exceeded recommendations during critical periods, reinforcing the need for frequent maintenance. It is concluded that the excavated structures implemented in the mine contributed decisively to the success of the 2024 Rain Plan, demonstrating effectiveness in containing and mitigating the environmental and operational impacts of the mine, ensuring the sustainability of water management and compliance with environmental standards.

Keywords: mine drainage, sediment containment, surface water.

Efficient removal of aqueous chromium using hydrothermally activated perlite

Berthy Indira Paye-Masco — 2026-01-24

The removal of chromium from wastewater has received considerable attention in recent years due to its harmful environmental effects. This study evaluated the chromium adsorption capacity of activated perlite obtained by a hydrothermal process using 20% NaOH and 30% NaCl. The experiments were performed using a synthetic Cr(OH)SO₄ solution containing chromium predominantly as Cr(III), as confirmed by chromium speciation analysis. Adsorption experiments based on a factorial design assessed the effects of initial chromium concentrations (401-1482 mg L^-¹) and activated perlite dosages (10-30 g L^-¹). The Langmuir isotherm provided the best fit to the data at 273.15-298 K, yielding a maximum adsorption capacity of 133 mg g⁻¹ and a Langmuir constant of 0.09 L mg⁻¹. Kinetic data were consistent with both pseudo-first-order and pseudo-second-order models. Hydrothermal activation increased the cation exchange capacity from 90.57 to 120.52 meq per 100 g. Statistical analysis indicated that chromium removal followed a linear model relative to both initial concentration and adsorbent dosage. These results demonstrate that hydrothermally activated perlite is a promising low-cost and sustainable adsorbent for the removal of Cr(III) from tannery effluents, with potential for large-scale implementation.

Keywords: adsorption isotherm, cation exchange, chromium, factorial design, hydrothermally activated perlite, kinetics.

Mobility of trace elements in soil-water systems near a decommissioned uranium mine: influence of environmental factors

Mariana de Oliveira Reis — 2026-01-24

Oligoelements are trace mineral substances that occur in minimal amounts in living organisms and can be either beneficial or toxic depending on their concentration and bioavailability. Understanding their mobility in soil and water systems is essential for assessing environmental and human health risks, particularly in areas affected by mining activities. This study evaluated the mobility of five trace elements—arsenic (As), selenium (Se), aluminum (Al), uranium (U), and molybdenum (Mo)—in soils near a decommissioned uranium mine in Salamanca, Spain. The soil was fractionated into three particle size classes and subjected to varying moisture levels (50%, 75%, 100%) and incubation times (one, seven, 30 days). Soil solutions were extracted by centrifugation at different speeds, simulating suction pressures associated with water availability in the soil. Concentrations in soil solutions ranged from As: 0.5–12.3 µg/L, U: 0.2–8.7 µg/L, Al: 0.8–15.4 µg/L, Mo: 0.3–6.2 µg/L, Se: 0.1–2.8 µg/L, depending on environmental conditions. Moisture increases from 50% to 100% raised As and U concentrations by up to 60%, while particle size shifts from coarse sand to silt/clay altered As levels by over 70%. Boxplot analysis revealed outliers for As, Al, U, and Mo, indicating strong sensitivity to soil texture and water availability. ANOVA confirmed particle size as the most influential factor (p < 0.05), followed by moisture and suction pressure, whereas incubation time showed no significant effect. These findings highlight rapid equilibrium and element-specific responses, with implications for groundwater contamination risk in post-mining landscape.

Keywords: environmental contamination, soil mobility, trace elements, uranium mine, water resources.

Continuous process for the effective removal of gasoline from an aqueous emulsion using mexicalcite as an adsorbent in a packed bed column

Julian Cruz-Olivares — 2026-02-02

Thanks to its extraordinary properties as an adsorbent, the mineral called “mexicalcite” was used to remove gasoline from a water emulsion in a continuous process. A glass column with an internal diameter of 1.6 cm was used to analyze the effect of the packed bed height (Z), flow rate (Q) and the influent concentration (C₀) on the percentage of gasoline removal (%R) and the adsorption capacity (q). The experimental results show that the effect of Z, Q, and C₀ is positive on the adsorption capacity, that is, an increase in the value of these three factors causes an increase in the amount of adsorbed gasoline. The only negative effect was found when the volumetric flow rate was modified; in this case, the percentage of gasoline removal decreased 8.7 and 15.4% when increased from 5 to 10 mL∙min^-1 and from 5 to 15 mL∙min^-1, respectively. Experimentally, the highest removal percentage (97.1%) and maximum adsorption capacity (132.23 mg∙g^-1) were obtained with a packed bed height of 4 cm, a volumetric flow rate of 5 mL∙min^-1 and an initial concentration of 1500 mg∙L^-1. The continuous process was successfully modeled using the Thomas, Adams-Bohart, Wolborska, Dose-Response, and Yoon-Nelson models. The Thomas and Dose-Response models yielded a maximum adsorption capacity of 125.31 mg∙g^-1. These results demonstrate that mexicalcite is a potential adsorbent for gasoline removal from water.

Keywords: adsorption capacity, gasoline removal, packed bed column, removal percentage, Thomas model.

Modeling and analysis of sediment discharge in three tributaries of the Mourão River basin, Brazil

Alexandre Rafael Kelniar — 2026-02-02

The transport of sediments in river systems has significant environmental and economic implications, affecting water quality, aquatic ecosystems, and the operational lifespan of hydraulic structures such as reservoirs. This study quantified and analyzed sediment discharge in three distinct river sections within the Mourão River basin in Paraná, Brazil, by applying and comparing various mathematical models. The three sampling sections were established on the Campo River (Section 1), the Mourão River (Section 2), and the Sem Passo River (Section 3). Bedload sediment discharge was calculated using the methods of Einstein (1942) with a Peter-Meyer modification, and Duboys (1879) and Zeller (1963). Suspended sediment discharge was estimated using the models of Yang (1973) and Righetto (1998) and compared with experimental results from total suspended solids analysis. Hydraulic characterization, including the development of rating curves and the calculation of the Froude number, was performed to understand the flow regime. The results indicated a subcritical flow regime (Fr < 1) in all three sections, characteristic of relatively slow-moving water. The Duboys (1879) and Zeller (1963) model was only applicable to Section 1, a smaller channel, as it yielded non-representative results for the larger perimeters of Sections 2 and 3 under the observed low-flow conditions. In contrast, the Einstein (1942) approach with the Peter-Meyer modification proved more robust, providing viable estimates for all sections. A strong correlation was found between the Froude number and the sediment discharge predicted by the theoretical models. This study highlights the critical importance of selecting appropriate models based on the specific hydraulic and geomorphological characteristics of the river channel and underscores the complexity of accurately predicting sediment transport.

Keywords: Froude number, mathematical modeling, Mourão River, rating curve, sediment transport.

Hydrological modeling and water allocation in the Piranhas-Açu River Basin in the eastern axis of the São Francisco River integration project

Lina Maria Osorio Olivos — 2026-02-02

This study presents the integrated application of the lumped hydrological model SMAP and the optimization library Pywr to assess water allocation in the Piancó-Piranhas-Açu river basin, located in the Brazilian semi-arid region. We developed comparative scenarios with and without inflows from the São Francisco River Integration Project (PISF), based on historical monthly series of rainfall and streamflow, combined with sectoral demands obtained from the National Water Use Register. Results showed that the PISF inflow, which began in December 2021, improved flow regularity, reduced the frequency of critical storage levels in the reservoirs, and increased the reliability of demand supply. Public water supply was the most benefited sector, with a significant reduction in deficits and higher frequency of full demand satisfaction, while irrigation showed modest improvements due to the legal priority of human consumption. These findings underscore the strategic importance of the PISF in strengthening regional water security and demonstrate the potential of integrated modeling as a decision-support tool, providing technical evidence for water management policies in critical semi-arid basins.

Keywords: PISF, semi-arid, water allocation.

Mineral nitrogen dynamics, mineralization and nitrification in soybean fields under No-Tillage and conventional tillage in Amazonian tropical soils

Nieli Eloine Roddrigues — 2026-02-04

This study evaluated mineral nitrogen (NH₄⁺ and NO₃⁻) concentrations and potential mineralization and nitrification rates in soils under No-Tillage (NT) and Conventional Tillage (CT) in soybean fields in the Santarém Plateau, Pará, Brazil. Soil samples were collected at three phenological stages (R1: flowering; R5: grain filling; R8: physiological maturity) and four depths (0 – 10, 10 – 20, 20 – 30, 30 – 40 cm). No significant differences were observed between NT and CT for mineral N concentrations or transformation rates, suggesting that after two years of NT adoption, short-term effects on N dynamics are minimal. Mineral N concentrations decreased significantly (p< 0.05) from R1 to R8, mainly in deeper layers (10 – 40 cm), likely due to intense N uptake by soybean during early reproductive stages. The highest daily mineralization and nitrification rates occurred in the 0 – 10 cm layer, associated with greater organic matter and microbial activity. Positive transformation rates at all depths indicate continuous conversion of organic N into plant-available forms throughout the crop cycle. Results suggest that NT benefits on soil N cycling in Amazonian agricultural systems may become more evident over longer adoption periods, particularly when integrated with crop rotation and permanent soil cover.

Keywords: agricultural management systems, ammonium and nitrate, nitrogen transformation rates, soil nitrogen cycling, tropical agriculture.