Ciência e Natura

Inovações e Soluções Sustentáveis em Engenharia Ambiental

Cristiano Poleto — 2025-05-21

Technological advancements and the pursuit of sustainable solutions have driven innovation in various fields of environmental engineering. In this context, studies aimed at optimizing processes and implementing eco-friendly alternatives stand out. This Special Publication presents some of the most recent and innovative research, providing a comprehensive view of initiatives focused on sustainability and efficiency.

For example, precise water flow measurement is essential for water resource management. The evaluation of Venturi meters as an alternative for residential flow measurement offers an effective and accessible solution for monitoring water consumption, promoting conscious use and reducing waste.

Another highlight is the estimation of the energy potential of biogas derived from UASB reactors in the state of Rio Grande do Sul. The use of biogas as a renewable energy source not only helps mitigate greenhouse gas emissions but also adds value to the use of organic waste, contributing to the circular economy.

Biosorption has gained traction as an alternative method for removing heavy metals from aqueous solutions. The optimization of coconut fiber as a biosorbent material for the removal of Pb²⁺ and Ba²⁺ stands out for its effectiveness and low cost, offering a sustainable and accessible alternative for water purification.

Water quality modeling based on HEC-RAS is of interest for monitoring and preserving water resources. These tools allow the analysis of various parameters and the identification of possible sources of pollution, facilitating the implementation of corrective measures.

Additionally, the chemical characterization of soil fractions from sanitary landfills for application as fertilizers or soil conditioners exemplifies the reuse of solid waste, reducing environmental impact and promoting sustainability in agriculture.

Finally, the application of artificial neural networks in CO₂ capture demonstrates the potential of artificial intelligence technologies to mitigate climate change, optimizing adsorption processes and increasing efficiency in the removal of polluting gases.

Thus, these studies reflect the ongoing commitment of environmental engineering to innovation and sustainability. The adoption of these and new solutions is essential to addressing current environmental challenges and ensuring a more sustainable future.

Estimation of the energy recovery potential of biogas from UASB reactors in the state of Rio Grande do Sul

Heron Vasconcellos Dilélio — 2025-05-21

The increase in sewage collection and treatment rates in Rio Grande do Sul (RS) should be guided by environmentally and economically sustainable practices. Anaerobic digestion, through UASB reactors, thus becomes potentially attractive because it allows, in addition to sewage treatment, the generation and collection of biogas - a biofuel with a high methane percentage. Therefore, the present work has investigated the scope of UASB reactors’ operation in Rio Grande do Sul, identifying that 76.5% of its Sewage Treatment Plants (STPs) use anaerobic technology, with 1/3 having UASB reactors. Using self-monitoring data from the sectioned STPs and through the Chemical Oxygen Demand (COD) conversion methodology adapted from Lobato, Chernicharo, and Souza (2012) – incorporating a methane solubility fluctuation factor to better estimate losses in the liquid phase –, the energy potential of biogas generation in the state was estimated in three different scenarios. The results demonstrate that Rio Grande do Sul has low potential in this field due to the large number of small STPs, sewage with low COD concentration, and high methane losses in the liquid phase. Future individualized studies that address the financial viability are necessary, encompassing the perspective of less noble uses of biogas in order to provide additional revenue to the state's STPs.

Evaluation of bacterial activity in a structured bed reactor under different organic loading rates (OLR)

Edgar Augusto Aliberti — 2025-05-21

This research aims to evaluate the bacterial activity response in a continuous upflow structured bed reactor for organic matter and nitrogen removal from dairy wastewater (with an initial concentration of 5,326 mg.L^-1 of COD and 39 mg.L^-1 of NH₄⁺-N) under different organic loading rates (OLR). An acrylic bench-scale reactor with a total volume of 2.27 L and a working volume of 1.32 L was used and operated for 271 days. The reactor was operated in three experimental phases with different OLRs: Phase I - 1.2 kgCOD.m^-3.d^-1 (107 days); Phase II - 1.4 kgCOD.m^-3.d^-1 (94 days); and Phase III - 1.8 kgCOD.m^-3.d^-1 (70 days). During operation, COD removals above 90% were achieved in all phases. For nitrogen removal, the best results were obtained in Phase I, with average removals of TKN and total nitrogen (TN) of 81% and 74%, respectively. The increase in OLR affected nitrogen removal by directly interfering with the ammonification process. The ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) concentrations decreased with higher OLR. However, despite these results, no accumulation of oxidized nitrogen forms was observed, indicating that nitrification and denitrification occurred simultaneously. The structured bed reactor, operated with recirculation and intermittent aeration, proved effective for simultaneous organic matter and nitrogen removal, creating a stable and favorable environment for combined processes under different OLRs.

Floods in the state of Acre in the brazilian Amazon: 2015 events, impacts and challenges

George Luiz Pereira Santos — 2025-05-21

Floods are stressful processes that disrupt the environment in which they occur. The aim of this article is to analyze, from an impact perspective, the largest flood on record in the city of Rio Branco, capital of the state of Acre, in the south-western Brazilian Amazon. It also aims to propose measures to reduce risks and minimize impacts. In 2015, the level of the River Acre reached a historic high of 18.40m (4.40m above its overflow level). As a result, 32 days were spent submerging more than 4,500 hectares of the municipality's urban area, with more than 100,000 people affected and more than 10,000 left homeless. The damage (human and material) and losses (economic and social) exceeded five hundred million reais. For the proposed analysis, the research focused on a literature review of works on risk perception, resilience and governance, in order to take in theoretical contributions and case studies focused on these themes, analysis of reports, plans and official documents, as well as research into official databases. The results showed severe negative social and economic impacts on the affected population and require, in the subjective (individual and community), institutional and governance context, tools and mechanisms to reduce the risks of their occurrence and minimize their impacts. Prevention and preparation for coping with them involve aspects of adaptive capacity, social participation, strengthening institutions and risk governance.

Inverse problem solution for microplastic emission source area estimation in MOHID: the Sepetiba Bay case study

Nikolas Gomes Silveira de Souza — 2025-05-21

Occasionally, contaminants are found on beaches (oil, plastic, etc.), and determining their origin can be challenging. However, the adaptation of computational tools with the capability of mathematical modelling of the motion of Lagrangian tracers can offer a practical and objective solution. In this study, it is presented a solution for the inverse problem of contaminant emission, with a focus on microplastic. For that matter, the computational platform MOHID was used to simulate the movement of Lagrangian tracers along the estuary connecting Sepetiba and Ilha Grande in Rio de Janeiro/Brazil. Two methods for tracing the origin of the particle were used, traditional backtracking, and a mapping method, both based on box and instantaneous emissions. The outputs were analysed and both methods yielded promising results, though additional criteria-based decision was found to be significantly relevant. In addition, it was observed the complex hydrodynamic ruling the particle motion, with significant longitude and latitude parameter sensitivity for a microplastic search. The mapping method observed the advantage of potentially reducing the time dependence of the model, while backtracking showed faster results. At last, the time and detail of each model output showed important differences, reinforcing the necessity for a criteria-based decision over the use of the model. This work contributes as a support tool for microplastic mitigation and cleansing-related activities and can be extrapolated to address other types of litter.

Temporal analysis of recurrence of flooded areas in Porto Alegre using Landsat and Sentinel-1 images

Vinícius de Azevedo Silva — 2025-05-21

This study uses the collection of Landsat images to analyze the recurrence of flooded areas in the Porto Alegre region, highlighting its entire temporal scale from 1984 to the present, analyzing the images with the highest index. Additionally, the use of Sentinel-1 data, despite its smaller temporal scale, is explored to complement the analysis of flooded areas. Using qualitative, quantitative and exploratory methodology, the research demonstrates that the joint use of technologies such as Landsat and Sentinel-1 significantly increases the potential for analysis and monitoring, providing a robust data set, which contributes to decision-making in the context of disaster mitigation and urban planning in vulnerable areas such as Porto Alegre.

Model for utilizing Associated Natural Gas with hydrogen in Pre-Salt offshore explorations

Antonio Carlos Dutra de Sousa — 2025-05-21

In the race towards energy transformation, countless efforts are being made to improve efficiency and mitigate greenhouse gas emissions. In oil exploration and production (E&P), Natural Gas (NG) is a primary product exploited alongside crude oil due to its excellent energy potential. Under primitive conditions, NG can be classified as either Associated NG or Non-Associated NG. Non-Associated NG is produced from reservoirs containing almost exclusively dry gas, free of crude oil and water. Associated NG, on the other hand, is NG that is dissolved in oil or in contact with saturated crude oil. In Brazil, the NG produced from offshore reservoirs is predominantly Associated NG and, in addition to being exported, is used locally in power generation, artificial lifting and injected into reservoirs. This method is widely used in E&P to increase the recovery factor of reservoirs. The use of Associated NG is provided for in Resolution No. 806 of 2020 of the ANP (Agência Nacional do Petróleo, Gás Natural e Biocombustíveis), which regulates the procedures for controlling NG losses and flaring. In E&P, since flaring is inevitable, it is proposed, with the NG currently used for flaring, to increase the utilization rate of Associated NG for hydrogen production through a modular structure suitably sized to fit the competitive space of a Floating Production Storage Offloading (FPSO) unit.

Synthesis and characterization of a sustainable adsorbent from WTP sludge and orange peel: application for removal of reactive blue BF5G dye

Camila da Silva Rodrigues — 2025-05-21

This study produced and characterized a mixed adsorbent material from Water Treatment Plant (WTP) sludge and orange peel waste (Citrus sinensis (L.) Osbeck) for use in the removal of Reactive Blue BF 5G dye from aqueous solutions. The pellets were thermally treated at 950ºC. The material produced, named MAT, was characterized for its chemical and surface properties using XRF, XRD, FTIR, SEM, BET, PZ, and pH-PCz. The results reveal that MAT showed promising chemical and mineralogical composition for adsorption, with a predominance of silica (>45%) and aluminum (>30%), a mesoporous and rough surface, negative charge under neutral conditions, and a buffering effect at pH 5.7. The dye removal efficiency of MAT was evaluated in terms of solution pH, temperature, contact time, and MAT mass. The results showed that MAT exhibited adsorption capacity and removal efficiency with the best performance at pH 3. The process was favorable at room temperature and rapid, using just one unit of the pellet. However, the adsorption capacity was lower than expected (q < 0.26 mg g⁻¹), suggesting that sintering at lower temperatures might be more suitable to optimize its effectiveness.

Mapping the treatment units of a Wastewater Treatment plant for diagnostic purposes

Amanda Santana dos Santos — 2025-05-21

The aim of this work was to study the performance of a Wastewater Treatment Plant (WWTP) in the municipality of Uberaba-MG, through evaluation of the data provided by the local sanitation company. Analysis of these data, collected at the main points of the treatment stages, made it possible to assess the overall efficiency of the sewage treatment process at the plant, as well as each specific stage. The removal efficiencies of the various parameters monitored were: COD = 91.50%, Ammoniacal-N = 33.10%, Total-P = 60.87%, ST = 48.02%, TSS = 91.66%, VSS = 92.82%, and FSS = 88.80%. In addition, the pH of the final effluent was always within the limits allowed by current regulations. The analysis highlighted aspects that could be improved to add value to the process as a whole. In addition, it was observed that inadequate values for any of the parameters analyzed can lead to underuse or overload of the plant units, compromising the effectiveness of the treatment as a whole, such as the low organic load applied to the UASB reactors, such as the low HRTs resulting from the complete-mix aerated lagoons and the facultative aerated lagoons.

Optimization of electrolytic process for the removal of the antibiotic ciprofloxacin from synthetic wastewater

Ismael Laurindo Costa Junior — 2025-05-21

Ciprofloxacin (CIP), an antibiotic of the fluoroquinolone class, has low biodegradability and possible toxic environmental effects. Due to its extensive use, it is considered an emerging contaminant (EC) in environmental compartments such as water, sludge, and sewage that contribute to antimicrobial resistance. This work assessed the optimal conditions for removing CIP in synthetic wastewater using electrolytic treatment and a laboratory-scale reactor with aluminum electrodes. The experiments were carried out from reconstituted synthetic wastewater fortified with 10 mg L^-1 of CIP. The operational parameters of the reactor, such as pH, voltage, and concentration of the supporting electrolyte (NaCl), were optimized based on the reduction of the CIP concentration through the complete factorial design 2³ followed by optimization by the response surface methodology employing central composite rotational design (CCRD) from the regression analysis of the quadratic model. The best operational condition obtained was pH = 7.6, voltage = 5.6 V, and [NaCl] = 0.6 g L^-1. In the validation tests, the removal achieved over 120 min was 78%, with equilibrium established after 80 min. It is suggested that, in addition to removing CIP by electrocoagulation mechanisms, there is also degradation by the electro-oxidation mechanism, promoted by oxidizing species produced from components of the reaction medium. The applied electrolytic process proved favorable and promising for removing CIP in synthetic wastewater.

Chemical characterization of landfill-mined-soil-like-fractions (lmslf) for application as fertilizer or soil conditioner

Lucas Antonio de Oliveira — 2025-05-21

Brazil is actively working to improve municipal solid waste (MSW) management and extract value from it. Landfill mining, the process of recovering materials from landfills, is a potential solution. One valuable component is landfill-mined soil-like fractions (LFMSF). These fractions, composed of a mixture of organic materials, soils, debris, and small fragments of metals, plastics, and glass, offer potential benefits for agriculture. A chemical analysis of LFMSF (D < 19mm) after eight years of landfilling (LFMSF-8) from the Delta A sanitary landfill in Campinas, Southeastern Brazil, revealed its nutrient content. The results showed that LFMSF-8 contains essential elements for plant growth. Notably, it meets iron (Fe) concentration requirements for remineralizers. Moreover, LFMSF-8 exhibits higher levels of calcium (Ca), iron (Fe), manganese (Mn), boron (B), and cation exchange capacity (CEC) compared to traditional organic fertilizers. Importantly, it presents low levels of potentially toxic elements (PTE). These findings suggest that LFMSF can be a valuable secondary nutrient source for agriculture. Its responsible use can contribute to a more sustainable and circular economy.

Optimizing an alternative method to remove Pb2+ and Ba2+ in aqueous solution by using coconut fiber as biosorbent material

Mário Sérgio da Luz — 2025-05-21

This work presents the optimization of an alternative method for the removal of lead (Pb²⁺) and barium (Ba²⁺) from public supply water using coconut fiber as a biosorbent material. A system of four fixed-bed reactors connected in series, each with a volume of 0.250 L, was employed, operated in an upward continuous flow. A central composite rotational design (CCRD) was used, where the critical values that maximized the removal of Pb²⁺ ions were: pH = 4.8; time = 57.11 min; and biomass concentration = 25.45 g/L. For Ba²⁺ ions, the critical values were: pH = 4.99; time = 53.41 min; and biomass concentration = 19.83 g/L. The removal percentage was determined at the critical values, and an increase in lead removal (from 82% to 88%) and a reduction in barium removal (from 94% to 89.2%) were observed when using four reactors in series. In the multi-elemental analysis containing both lead and barium simultaneously and using the average values found for the ions analyzed separately (pH = 5.0; time = 55.26 min; biomass concentration = 22.64 g/L), there was a slight reduction in lead removal (from 81.2% to 78%), but within the standard deviation, and barium removal remained stable (92.6%). Thus, this alternative method proved to be promising for the removal of potentially toxic metals in public supply water.

Nutrient removal in anaerobic-aerobic reactors followed by a trickling filter

Raphael Augusto Ferreira Gatti — 2025-05-21

This study aimed to evaluate the performance of a combined system used in nitrogen and phosphorus removal, with a variation of the hydraulic retention time (HRT) and the recirculation rate (R). The system consisted of three sequential reactors operated in series, composed of an anaerobic reactor (20 L), an aerobic fixed bed reactor (19 L), and a trickling filter (16 L). The recirculation rates of 150, 100, and 50% and HRT of 9, 7, and 5 h have been, with a constant aeration flow of 10 L min-1. For system evaluation, liquid temperature, pH, total alkalinity, bicarbonate alkalinity, volatile acids, dissolved oxygen, chemical oxygen demand, Kjeldahl total nitrogen, nitrogen ammonia, nitrite, nitrate, and total phosphorus have been analyzed. The combined system has reached achieved organic matter removal efficiencies of 99%, 98%, and 98% for the recirculation rates of 50, 100, and 150%, respectively. Under the same R rates, TKN removal efficiencies resulted in 96, 89, and 87%, and TP removal efficiencies in 78, 82, and 77%, respectively. When operated with HRT of 9, 7, and 5 h, the combined system achieved removal efficiencies of 86, 96, and 98% for COD, 90, 93, and 94% for TKN, and 74, 89, and 95% for TP, respectively. The best operational condition was experimentally established having with a recirculation rate of 150% and HRT of 5 h. However, after experimental validation by CCRD (through desirability), the optimal operational condition resulted in a recirculation rate of 123% and HRT of 5 h for TKN and PT removal efficiencies.

Influence of the recirculation rate on the performance of Anerobic Aerobic Fixed Bed Reactor (AAFBR)

Daiane Cristina de Freitas — 2025-05-21

The objective of this research was to evaluate the influence of the recirculation rate on nutrient removal and on the hydrodynamic behavior of a fixed-bed anaerobic-aerobic reactor, operated on a bench scale, in the treatment of sanitary effluent. Different recirculation ratios (0.5, 1.0 and 1.5) were tested with a constant air flow of 10 L min-1. During the operation period, the physicochemical parameters were analyzed. Hydrodynamic tests were also carried out using pulse stimulus-response tests with the eosin Y tracer, to evaluate the hydrodynamic behavior and investigate anomalies. The 50% recirculation ratio proved to be the condition with the highest removal efficiency for total solids (83%). The 100% recirculation ratio was the most efficient for TKN (97%) and Nammon (99%). For the recirculation ratio of 150%, the highest removal efficiency was for phosphorus (33%). As for hydrodynamic behavior, according to the correlation of the theoretical uniparametric models tested, it is possible to state that the recirculation ratios of 50%, 100% and 150% presented correlation coefficients that indicate complete mixing, with good hydraulic efficiency for recirculation. of 100%. By varying these factors, it was possible to verify the influence of the recirculation ratio on the removal of nitrogen and phosphorus, as well as on the hydrodynamic behavior of the reactor.

Applications of artificial neural networks in CO2 capture: mitigating climate change through adsorption processes

Suzan Roberta Tombini Venturella — 2025-05-21

Since the Industrial Revolution, atmospheric CO₂ levels have increased from 280 ppm to 420 ppm by 2022, raising concerns within the scientific community about climate change. Carbon capture through gas adsorption on solid surfaces has emerged as a viable technique to address this issue. This study employed artificial neural networks (ANN) to predict CO₂ uptake on activated carbon under various experimental conditions, using data such as pressure, temperature, adsorbent surface area, and uptake of CO₂ and CH₄. The network was trained, validated, and tested using the Levenberg-Marquardt algorithm in Matlab©, exploring architectures with 10, 15, and 20 neurons. The best performance was achieved with the 20-neuron architecture, yielding an MSE of 3.80x10⁻³ and R² values of 0.98347, 0.98328, and 0.97365 for training, validation, and testing, respectively. Additionally, the Garson method was utilized to assess the importance of the input variables, revealing that the most influential variables were surface area at 50.06%, CO₂ molar fraction at 13.92%, and methane molar fraction at 13.89%. These results demonstrate the effectiveness of the ANN model in predicting CO₂ adsorption, highlighting the potential of combining experimental methods with machine learning for the efficient study of greenhouse gas capture while reducing the costs and time associated with laboratory experiments.

Can venturi flowmeters be used to measure residential consumption?

André Luís Sotero Salustiano Martim — 2025-05-21

Flow measurement is critical for the management of processes involving fluids. Depending on their location, meters can be classified as macro flow meters or customer flowmeters. Accounting for water inflows and outflows is essential to manage revenues and losses and can be measured through different instruments with different principles of application. A few research related water losses and the use of macro flowmeters in the water distribution networks (WDN) regarding its precisions and costs. For residential consumption registration, volumetric and velocimetric meters are often the most used type of meter as it presents a good cost/efficiency relation. In this sense, the main objective of this research was to compare the simple Venturi meter with the most used residential flowmeters: velocimetric, volumetric and ultrasonic meter. Experimental studies were carried out on a 20 mm diameter calibration bench by volumetric method, in the calibration facilities laboratory. Experimental results are presented and analyzed. Results shows that by applying a discharge coefficient based on experimental adjusted equations Venturi meters can perform similarly to the other meters studied.

Water quality modeling in the Paraguay River basin using HEC-RAS

Matheus Guilherme Ramin — 2025-05-21

The Upper Cuiabá River Basin, located in the Planning and Management Unit P4 (UPG-P4) on the plateau of the Paraguay River Basin, is an area of significant interest for water quality control. This region, which is home to approximately one million people, is experiencing rapid agricultural expansion. Being upstream of the Pantanal, one of the largest wetlands in the world, it becomes a region of great importance for environmental management. The primary water quality issues in the Paraguay River Basin are caused by the transport of sediments and diffuse pollutants from the plateau to the Pantanal. In this context, this study evaluated the impact of phosphorus control measures in UPG-P4 on the water quality of the Cuiabá River, using the HEC-RAS software for steady-state one-dimensional modelling. Four scenarios were simulated in the study, showing that the phosphorus limits of Class 2 of CONAMA Resolution 357/2005 were met only in Scenario 1 (an 80% reduction of phosphorus in pasture and agricultural areas), and only in the section between the Manso River and the beginning of the urban area of Cuiabá. The study found that pasture areas have a more significant impact than agricultural areas, and the model proved useful for planning water quality control and can be adapted for other regions of the Paraguay River Basin.