ABSTRACT This study describes an assessment of 36 wastewater treatment plants (WWTP) located in 12 municipalities in Minas Gerais (Brazil) to identify operational issues and improvement opportunities. The aim was to conduct an integrated assessment of full-scale wastewater treatment plants based on multiple analytical methods, including checklists, field inspections, interviews with operators and managers, a comparison with the standards of the Brazilian Association of Technical Norms, and monitoring data analysis. The predominant systems were Upflow Anaerobic Sludge Blanket reactors (19 WWTP), followed by Septic Tank + Anaerobic Filter (15 WWTP), and activated sludge (two WWTP), with design flow rates ranging from 0.5 to 83.3 L.s-1. Of the 36 WWTP identified, 30 were operational at the time of site inspections. The assessments highlighted several operational deficiencies, including: (i) limited flow measurement infrastructure, with Parshall flumes available in only 19 WWTP; (ii) lack of routine sludge and scum removal practices; (iii) poor compliance of design parameters with technical standards, which was verified in only three of 11 septic-tank plants, seven of 18 anaerobic filter plants, and two of 13 UASB reactor plants; and (iv) the absence of monitoring data in 20 WWTP. For the ten WWTP with available monitoring data, compliance with effluent discharge standards was generally low. The results emphasize the need for improvements in wastewater treatment plant operation and management, while also identifying opportunities to reuse treated effluent in agriculture, transform sludge into biosolids, and consider the growing role of intermunicipal sanitation consortia in strengthening technical and institutional capacities.
ABSTRACT A elevação das temperaturas globais, fator determinante da emergência climática, vem gerando impactos em eventos climáticos extremos e intensificando desafios socioambientais. Nesse contexto, torna-se urgente otimizar as políticas públicas ambientais, especialmente em relação à gestão de recursos hídricos - uma questão crítica no Brasil, onde a Política Nacional de Recursos Hídricos estabelece diretrizes para o uso sustentável. Destacam-se, nesse cenário, os planos de bacia hidrográfica, que orientam o planejamento dos recursos hídricos, e os pagamentos por serviços ambientais (PSA), instrumento econômico instituído pela recente política nacional de PSA para incentivar a conservação por meio de transferências entre provedores e beneficiários de serviços ambientais. Este estudo analisou a integração entre esquemas de PSA relacionados à água e os planos de bacia hidrográfica no Brasil, buscando identificar sinergias para aprimorar a governança. A metodologia combinou análise documental com entrevistas qualitativas, categorizando os níveis de integração. Os resultados revelaram que apenas 26,6% dos PSA (12/45) apresentaram integração alta ou muito alta com os planos de bacia hidrográfica, enquanto 31,9% dos planos (51/160) demonstraram integração alta ou muito alta com iniciativas de PSA. Esquemas vinculados a comitês de bacia hidrográfica ou agências de água demonstraram maior coerência com os planos de bacia hidrográfica, ao contrário de iniciativas municipais ou estaduais, frequentemente desconectadas do planejamento regional. Identificaram-se outros problemas, como integração geográfica limitada e ineficiência no monitoramento. As conclusões indicam que, apesar de alguns avanços, prevalece a falta de coordenação entre PSA e planos de bacia hidrográfica, com consequências negativas para a governança hídrica. O estudo ressalta a necessidade de uma coordenação mais robusta entre esses instrumentos.
ABSTRACT Sanitary landfills are environmental facilities designed for the final disposal of municipal solid waste and represent the most widely used method for waste management in many countries. Knowledge of the geotechnical properties of these materials is essential for understanding processes occurring within landfills, such as leachate generation, gas production, settlement development, and slope stability. Municipal solid waste has a highly heterogeneous composition, including organic matter, plastics, metals, and paper, which leads to significant variability in its hydromechanical behavior. Parameters such as hydraulic conductivity, shear strength, and compressibility differ considerably from those typically observed in soils and are strongly influenced by waste composition, compaction conditions, and degradation processes over time. This paper presents a literature review of the main hydromechanical parameters of municipal solid waste disposed of in sanitary landfills. The study discusses the influence of waste composition, unit weight, effective stress, and biodegradation on hydraulic conductivity, shear strength, and compressibility. In addition, typical ranges of values reported in the literature are presented and critically analyzed, with emphasis on studies conducted in Brazilian landfills. The results highlight the significant variability of municipal solid waste properties and reinforce the importance of site-specific investigations for landfill design and stability analysis.
ABSTRACT Population growth has driven the exploitation of water resources, often accelerating their eutrophication, the magnitude of which is associated with land use and land cover in their drainage area. This study aims to determine which tributaries exert the greatest influence on the eutrophication of an artificial reservoir used for public supply. To this end, the evolution of land use and cover, and the water quality of its main tributaries, were evaluated. Two land use and land cover maps were generated using MapBiomas (years 2000 and 2022), and the Global Rate of Change (Mahamba et al. 2022) was calculated for them. Water quality parameters historically linked to eutrophication were also evaluated using descriptive statistics, and the results were compared. The sub-basins with predominant human activities were identified as having the highest concentrations of nutrients. However, the tributary identified as the main predictor of total phosphorus concentration in the reservoir is less polluted. Because it has a higher flow rate, it still satisfactorily dilutes the contributions of the others, so that, after treatment in accordance with the legislation, the reservoir’s waters can be used for supply. The analysis of the available qualitative parameters highlights total phosphorus concentration as the main factor compromising reservoir quality. Therefore, it is essential to control its contributions by managing land use and cover in the drainage area to ensure its continuity as a source of public supply.
ABSTRACT This study numerically investigates the transport and deposition of polydisperse dense particles in a bifurcated fracture with variable intersection angles (θ). A Lagrangian particle tracing simulation was conducted using COMSOL Multiphysics software to track particle trajectories. Particles were injected at the inlet of the parent fracture and transported under the influence of drag and gravity forces. The transport parameters were derived by fitting the model to the 1D advection-dispersion equation. The results indicate that intersection angles significantly influence fluid flow and particle mobility, with nonlinear velocity variations becoming pronounced at θ > 90°. Higher flow velocities enhanced particle mobility at θ = 30° to 60°. However, increasing intersection angles and velocities led to a reduction in concentration plateaus due to increased mixing and attachment to the fracture walls. The dispersion coefficient decreased after reaching optimal angles of 30°, 60°, and 150°, depending on flow velocity. The deposition coefficient increased at higher velocities due to enhanced particle-wall interaction. The mean residence time analysis revealed that wider bifurcation angles increased retention, while larger apertures reduced mean residence times due to higher particle velocities. Particle size distribution also plays a major role, as particles with a radius of 0-2 μm exhibit a higher retention rate. This study provides valuable insights for designing and managing subsurface sanitation systems, controlling contaminant transport, and developing environmental remediation strategies in fractured rocks and the soil environment.
ABSTRACT Waterborne viruses, such as adenovirus, herpesvirus, severe acute respiratory syndrome coronavirus 2, and vaccinia virus, pose a health risk due to their persistence and structural variability. Ultraviolet C light-emitting diodes have emerged as a promising alternative to conventional mercury lamps, due to their energy efficiency, durability, and absence of mercury. This study evaluated the inactivation of these four viruses in water by exposure to light-emitting diodes with wavelengths of 265 nm and 275 nm. Ultraviolet light doses were quantified by chemical actinometry; inactivation kinetics were adjusted to log-linear and Weibull models, and statistical differences between treatments were evaluated by analysis of variance (p < 0.05). Results indicated a reduction ≥ 4 logs for all viruses, with doses ranging from 19.0 to 40.9 mJ/cm², depending on the virus, lower than those found in the literature for conventional systems. The Weibull model showed a better fit, suggesting resistant viral subpopulations. No statistically significant differences were observed between wavelengths in all viruses. It is concluded that ultraviolet C light-emitting diodes are highly effective for viral disinfection in water, offering a sustainable and energy-efficient alternative for water disinfection applications.
ABSTRACT Water treatment sludge is a widely generated but underutilized byproduct with potential applications in coagulant recovery, adsorptive properties, and wastewater treatment. This study aims to analyze the historical and temporal evolution of research on water treatment sludge. A Scientometric Review was conducted using the Methodi Ordinatio 2.0 methodology, analyzing 544 articles from Scopus, Web of Science, and ScienceDirect. After filtering, 198 articles were selected. VOSviewer and Microsoft Excel were used to map and generate graphical analyses. The results showed a sharp increase in publications after 2015, led by China, India, Australia, and Brazil. The most frequent keywords were "water treatment," "adsorption," "sludge," and "water treatment sludge." Yaqian Zhao was the most prolific author, while the Journal of Environmental Management and the Journal of Cleaner Production led in publications. Trends reflect a growing focus on sustainability and the circular economy, but reveal gaps, such as toxicity and hormone degradation. The findings support decision-making in waste management. Future research should explore practical applications, especially regarding toxicity and removal of emerging contaminants.
ABSTRACT Antimicrobial resistance is one of the most pressing challenges to global public health, and wastewater treatment plants play a role in the environmental dissemination of antibiotic resistance genes. This study assessed the occurrence and removal of clinically relevant antibiotic resistance genes in six small-scale wastewater treatment plants based on anaerobic technologies in Brazil. Raw and treated wastewater samples, collected between January and July 2025, were analyzed by qPCR targeting the genes blaKPC, blaNDM, blaOXA-48, blaOXA-23, blaVIM, blaCTX-M, mecA, vanA, mcr, and sulf1. Antibiotic resistance genes were consistently detected at high concentrations in influents — blaKPC (4.7–8.3 log10 GC·mL-1) and sulf1 (8.6–10.1 log10 GC·mL-1), both present in 90% of samples. Effluent concentrations remained elevated (blaKPC: 5.3–7.6; sulf1: 8.6–10.2 log10 GC·mL-1), indicating low removal efficiency. Overall log reductions were low (<1.0 log unit) for most genes, with cases of negligible removal or persistence regardless of technological configuration. Spearman correlation revealed weak associations with physicochemical parameters (p < 0.05), with blaNDM being the only gene showing significant correlations (negative with COD and solids). Redundancy analysis indicated that these variables explained only a small fraction of antibiotic resistance gene variability. The results highlight the persistence of resistance genes in anaerobic systems and underscore the need for enhanced treatment strategies to mitigate the environmental dissemination of antimicrobial resistance.
ABSTRACT Municipal Solid Waste Management Plans and reverse logistics systems are instruments defined in the Brazilian National Solid Waste Policy for eschewing landfill disposal in favor of non-generation, reduction, reuse, recycling, and energy recovery, in that order. Reverse logistics is a major challenge in Brazil due to regional diversity, country size, waste generation rates, and historical management deficiencies, with landfill disposal still being the main municipal solid waste strategy. Additionally, recycling depends heavily on waste pickers, who mostly work informally. Municipalities are required to have a Municipal Solid Waste Management Plan to receive federal funds and invest in waste management projects. It must contain a detailed diagnosis of waste generated in the municipality, management strategies, goals, and control mechanisms. Municipal Solid Waste Management Plans must include requirements for reverse logistics system implementation, as the absence of clear details on how such systems work can hinder reverse logistics progress. To identify how Municipal Solid Waste Management Plans address reverse logistics systems, the plans of 40 municipalities in the state of São Paulo were analyzed. Reverse logistics systems for electronics, batteries, light bulbs, medicines, waste tires, and assorted packaging were found to be at different implementation stages. Overall, plans address reverse logistics superficially, with no goals established. They also lack mechanisms to integrate different players and environmental education programs, which are fundamental to fostering citizen participation.
ABSTRACT Reducing losses in water distribution systems is a global objective. In Brazil, the new legal framework for sanitation sets a goal of 25% losses by 2033, while recent national data still indicate loss levels of around 40% in distribution systems. Joinville, in Santa Catarina, has total losses of 41.8% in its water supply system (28.5% were real losses and 13.3% were apparent losses in 2022). This highlights the need for structured investment planning focused on infrastructure renewal. This study applies performance indicators developed by the International Water Association to calculate an Infrastructure Vulnerability Index for water distribution infrastructure and rank operational sectors in Joinville’s R02 water supply system according to their structural vulnerability. The analysis is based on 510 maintenance records (139 network repairs and 371 service line repairs) between December 2022 and December 2023, combined with network and service line inventories for seven operational sectors. The resulting infrastructure vulnerability indices range from 8.1 (“Fair”) to 22.2 (“Very poor”), with the highest values observed in booster pumping sectors operating under elevated pressure conditions, which together account for only 6% of the total network but concentrate the worst vulnerability levels. These findings identify priority areas for the replacement and renewal of networks and service lines. The findings also show, in a real operational context, how infrastructure vulnerability index-based diagnoses, integrated with geospatial analysis, can support more efficient investment planning for reduced losses in Brazilian water utilities.
ABSTRACT This article presents a systematic and critical analysis of rain gardens in both global and Brazilian contexts. A systematic literature review was conducted, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, with analysis of 43 articles published between 2014 and 2024, retrieved from the ScienceDirect, Web of Science, and SciELO databases. Quantitative synthesis indicates that hydrological efficiency is directly proportional to soil profile depth: optimized systems (> 1.2 m) achieve volume retention exceeding 80% (compared to 44% in shallow profiles), while infiltration rates reported in Brazil average 312 mm/h. Despite their proven effectiveness in pollutant removal and runoff control, the review identified clear gaps, including premature clogging caused by sediment accumulation, vegetation selection based on aesthetic criteria rather than root-mediated treatment capacity, and the inappropriate replication of design parameters from temperate to tropical climates. The study concludes that Brazil remains at an experimental validation stage, in contrast to the consolidated application of rain gardens in international public policies. The primary scientific contribution of this work lies in proposing a tropicalization agenda for engineering guidelines, emphasizing the need for long-term monitoring and the integration of modeling tools to achieve more robust technical outcomes.
The presence of deionized chemical contaminants in waterways poses significant threats to aquatic ecosystems and human populations. This research investigates the efficacy of banana peel (Musa spp.) as a natural adsorbent for treating textile dye-contaminated water. Isotherm and kinetic model types showed that chemisorption was the rate-limiting phase in monolayer adsorption. The maximum adsorption was 28.7 mg/g. Hydroxyl, amine, and carboxyl functional groups detected in the FTIR spectrum provide active sites that promote the adsorption of dye molecules onto the adsorbent. The usual solution eliminated 92.8% of dyes under optimal conditions. The experimental results identified optimal treatment parameters of 0.5 g adsorbent dosage, 7.0 pH, 100 mg/L initial dye concentration, and 60 min contact time. Under these conditions, the system achieved 83.9% dye removal efficiency. While the low dye adsorption capacity in industrial effluent (83.9%) compared to synthetic solutions (92.8%) reflects matrix complexity, banana peels remain effective for real-world textile wastewater treatment. Significantly, a simple acid-base process enables 95% dye recovery, demonstrating both the adsorbent's reusability and circular economy potential for sustainable water treatment.
Biological and physicochemical methods are commonly used to remove phosphorus (P) from wastewater; however, these can present limitations. Therefore, this study aimed to evaluate the effectiveness of water treatment plant sludge from the Federal University of Lavras campus and natural zeolite. The chemical composition and pH were analyzed. Two experimental adsorption assays were conducted in phosphate solutions at concentrations of 25, 50, 75, and 100 mg.L-1 P-PO43-, designated as P25, P50, P75, and P100, respectively. In the first test, sludge and zeolite were used in both powdered and granular forms. The second test evaluated combinations of adsorbents: S10Z40, S20Z30, S25Z25, S30Z20, and S40Z10. All experiments were performed in triplicate using 0.5 g of adsorbent in 50 mL of P-PO(4)(3- )solution, agitated at 70 rpm for four hours in a Wagner agitator. The sludge and zeolite samples consisted mainly of iron (Fe), silicon dioxide (SiO2), and aluminum oxide (Al2O3), and the pH of both ranged from 7.5 to 8.0. The granular sludge adsorbent achieved approximately 97% removal at phosphate concentrations (P75 and P100) in the first assay, while zeolite efficiency was consistent across forms, reaching 96% for P75.The second assay showed reduced efficiency, with approximately 20% removal for P25 (p < 0.05) in both S30Z20 and S40Z10 conditions and 14% for P50. For P75 and P100, combined removal did not exceed 10%. These findings highlighted the individual adsorptive capacities of sludge and zeolite under different particle size conditions when applied independently.
This study assesses the impact of a 2015 public-private partnership on sewage system management in a large city in Brazil's SoutheastRregion, using 14 performance indicators from the National Sanitation Information System for 2007-2014 and 2015-2022. Interrupted Time Series models and complementary tests detected no statistically significant immediate level change at the public-private partnership initiation for ten indicators, while eight indicators improved in the post-intervention trend - most notably treated sewage volumes and urban/total service coverage rates. After adjusting for official inflation, the average sewage tariff increased by 32 percentage points in 2015-2022 compared with 25 percentage points in 2007-2014, alongside higher sector investment, indicating tariff and investment dynamics consistent with service expansion.
It is widely acknowledged that appropriate land use management within watersheds can prevent additional water treatment costs. However, the short-term economic benefits are relatively modest, often discouraging administrators from committing resources to watershed conservation. The existing literature lacks a comprehensive explanation of how watershed quality affects water treatment costs in the long term. Within this context, this study employs operational and water quality data from five drinking water treatment plants in Caxias do Sul, southern Brazil, to define, quantify, and illustrate the "short-term blurring effect" on water security. This effect refers to situations in which small short-term variations in treatment costs mask substantial long-term economic risks. In the short term, results show that a one-unit improvement in the water quality index yields an average reduction of only 0.0002 USD center dot m-3 in chemical treatment costs. Nevertheless, in the long term, the cumulative effect of watershed quality deterioration may require the adoption of more sophisticated treatment technologies, such as membrane filtration, ultimately augmenting costs by approximately 83 to 242%. These findings demonstrate that reliance on short-term economic indicators can distort water security planning and highlight the need to incorporate long-term treatment costs into watershed management decisions.
Sewage sludge management is a significant environmental challenge in the Puno region, where direct discharge into aquatic ecosystems leads to sedimentation, deteriorating water quality, and reducing wastewater treatment efficiency. This study aimed to evaluate and compare the quality of biosolids produced from sewage sludge treated in stabilization ponds in the cities of Puno, Juliaca, and Ilave, using thermophilic anaerobic digestion. The sludge was processed in biodigesters for 30 days under controlled temperatures of 50-60 degrees C. Physicochemical and microbiological analyses were performed to determine macronutrient content (nitrogen, phosphorus, potassium), organic matter, and pathogen reduction. Results showed the highest nitrogen (28,336 mg kg-1) and phosphorus (7,200 mg kg-1) concentrations in Puno, while Juliaca recorded the highest potassium level (4,447 mg kg-1). A significant reduction in fecal coliforms and helminth eggs was achieved, reaching an index of 2.68 HH/4gTS. Biosolids from all three sites were classified as Class B, with comparable nitrogen and organic matter content, but with site-specific nutrient profiles. It is concluded that thermophilic anaerobic digestion represents a sustainable and effective method for sewage sludge management in high Andean areas, with the potential to produce nutrient-rich biosolids suitable for agricultural applications.
Risk analysis is widely recognized for its simplicity and effectiveness in identifying and categorizing potential threats. It is based on two essential criteria, probability and consequence, allowing for risk prioritization and the adoption of preventive measures. In this context, the present study applies the Probability and Consequence (P&C) analysis methodology, combined with geospatial interpolation, to assess water quality and ensure water security in the municipality of Conceig & atilde;o do Araguaia, Par & aacute;. To achieve this, the methodological steps included parameter identification, on-site sampling, risk quantification, geostatistical modeling, and cross-validation. The results identified 19 sampling points classified between high and critical risk. The validation analysis revealed high local heterogeneity, indicating that micro-local factors drive contamination. Despite this variability, the map proved effective in identifying macroscopic zones of vulnerability, optimizing resource allocation by focusing inspections on critical clusters. The analysis showed that pH, nitrite, total coliforms, and E. coli were the main risk factors in the studied region. Thus, this study contributes to strengthening water security by proposing a zonal management approach, providing support for implementing preventive strategies to protect water resources and public health.
This study investigates critical barriers hindering Sustainable and Integrated Solid Waste Management (S-ISWM) in the Brazilian Amazon. Employing a four-stage methodology-(a) systematic literature review, (b) instrument development, (c) quantitative validation using Lawshe's method, and (d) results interpretation-the research identifies and validates key obstacles specific to this complex region. An initial review of the literature identified 13 common barriers to waste management in developing countries. Expert validation using Lawshe's method in the Amazonian context confirmed 11 as significantly relevant, demonstrating consensus among local researchers, private-sector professionals, and public-sector agents. The remaining two barriers exhibited divergent expert opinions, potentially reflecting nuanced perceptions of contextual factors and regional limitations. These findings underscore the need to understand the unique challenges involving waste management in the Amazon, where local conditions directly impact the effectiveness of potential solutions. The validated barriers offer essential insights for formulating targeted public policies and strategies that promote sustainability and effective waste management practices tailored to the Amazonian context.
ABSTRACT Optimizing the carboxylate platform during continuous sugarcane vinasse fermentation requires overcoming hydrolytic bottlenecks and steering metabolic pathways. This study investigated kinetic patterns and metabolic flux redirection in response to strategic interventions: lactate and glycerol supplementation and effluent recirculation. First-order modeling revealed that while carbohydrate hydrolysis is the baseline rate-limiting step (kapp = 0.4-1.8 h⁻¹), glycerol co-fermentation triggered a redox-driven “flash consumption” (kapp of 23 h⁻¹), bypassing hydrolytic constraints. Targeted lactate supplementation shifted the mixed-acid profile toward butyrogenesis, generating metabolic-derived alkalinity (pH > 7.0) and preventing acidification. Co-supplementation of glycerol and lactate created a controlled hybrid spectrum of propionate and butyrate. Furthermore, effluent recirculation activated in situ chain elongation via reverse β-oxidation, leveraging endogenous electron donors to double valerate production. Crucially, these strategies governed sulfur dynamics by partitioning toxicity between gaseous H2S or dissolved sulfide based on environment buffering. Principal Component Analysis (PCA) revealed that these interventions do not merely increase yields but deterministically restructure the microbial metabolic network. These findings provide a robust, kinetic-based framework for scaling up stable and selective sugarcane biorefineries.
