In Brazil, wastewater treatment system (WWTP) use stabilization ponds due to their ease of operation and relatively low implementation cost. Although effective at removing organic matter, these ponds can contribute to the eutrophication of the receiving water body (if it is sensitive to the eutrophication process), due to the high nutrient loads present in the treated effluent. Likewise, stabilization ponds can pose a problem for human health if the treated effluent is discharged into the receiving water body containing some type of cyanotoxin or other persistent toxic substances. In this way, this research sought to analyze the stabilization ponds of the Paranoá WWTP, as well as the water body receiving the treated effluent (Paranoá River), with regard to physical, chemical and biological parameters. The focus of the research was to analyze the dynamics of cyanobacteria in the high rate algal ponds (HRAP) in the dry and rainy periods, as well as to identify isolates and cyanobacteria and evaluate the production of cyanotoxins. In addition, we sought to investigate the influence of different N/P ratios on the growth of the isolated cyanobacterial strain Geitlerinema amphibium. To do this, samples were taken from the Paranoá WWTP during the dry and rainy seasons and the parameters pH, turbidity, electrical conductivity, temperature, dissolved oxygen, total phosphorus, total nitrogen, COD, total suspended solids and chlorophyll-a were analyzed in the laboratory. The results indicated that the density of cyanobacteria in various lagoons of the WWTP showed a positive correlation with different parameters, such as DO, chlorophyll-a, temperature and pH. High densities of cyanobacteria cells were observed in the final effluent and in the Paranoá River after the effluent was discharged. In addition, high concentrations of nutrients discharged into the river generated supereutrophic conditions at the point of discharge. Although the stabilization ponds are similar in terms of their design parameters, there was great variability between them, since the effluent leaving the UASB reactor is not divided equally between the ponds. In the samples collected, the presence of Geitlerinema amphibium and Phormidium sp. was detected in the lagoons and in the final effluent, both species of cyanobacteria potentially producing cyanotoxins. However, no cyanotoxins were detected in the isolated G. amphibium strain or in the final effluent. In the experimental study, the growth of Geitlerinema amphibium was more favorable in the N/P = 40/1 ratio treatment, indicating the strain's affinity with nitrogen-rich environments. However, the responses of this species to the N/P ratios in situ in the HRAPs were different. The results obtained can contribute to the optimization of treatment conditions in WWTPs and provide important information for the development of water quality management policies. As a result, this work highlights the importance of implementing appropriate technologies to efficiently treat domestic sewage and, in stabilization ponds, monitor and control cyanobacteria in these systems to ensure water quality, protect public health and the environment.

This study investigated the water quality of the Alagado stream (DF/GO) through the analysis of water quality parameters, the application of the classification compliance index, and hydrological and water quality modeling using the SWAT+ model. Additionally, three different landscape units were analyzed to understand their unique characteristics and their impact on the results for the delineation of LSUs, flow, and water quality. The results revealed that certain parameters, such as phosphorus and coliforms, exceeded regulatory limits, indicating a concern with pollution. The SWAT+ model for water quality did not achieve satisfactory calibration. However, despite the limitations, it provided valuable insights, such as the distribution of nutrient contributions, like phosphorus and nitrogen, from surface runoff, as well as data on the basin's evapotranspiration. These results are crucial for understanding the hydrological processes and pollution sources in the studied area. Furthermore, the analysis of different landscape units revealed significant disparities. The DEM Inversion method unit proved to be closer to reality when compared to slope factors, elevation, and the LS factor, suggesting a more realistic representation of the environment. This study is particularly relevant because the Alagado stream is one of the main tributaries of the Corumbá IV system, in the segment of the reservoir where surface water is captured to supply the Federal District and municipalities in the state of Goiás. Therefore, the results of this work aim to contribute to the management and conservation of this transboundary water body, highlighting the importance of pollution control measures and sustainable management strategies to ensure the region's water security.

Microplastics (MPs) pollution is a growing concern due to the accumulation of these materials in the environment. In this study, spot samples from nine sampling in the wastewater treatment plant (WWTP Norte) Brasília Norte were analyzed. To identify microplastics in samples, several methods and procedures have been developed and evaluated, including the production of reference microplastics, resistance of polymers to digestive methods, and particle extraction. The procedure selected for sample treatment was materialized by a digestion step of Fenton's reagent organic matter, followed by density separation with ZnCl₂ solution. Microplastic identification was carried out visually (microscopy) and assisted by chemical analysis using FTIR-ATR spectroscopy. The results showed the significant presence of microplastics, especially textile fibers, of different shapes and colors, in different particle sizes in all treatment units evaluated, with a majority composition of HDPE and LDPE. Furthermore, quantification revealed that the WWTP Norte released the final effluent at a concentration of 150 ±18 MP/L into Lake Paranoá. Additionally, in this study magnetic nano-powders based on iron oxide functionalized with citric acid (NP-Fe₃O₄@AC) were used to remove a consortium of microplastics composed of HDPE, LDPE and PP in proportions 1:1:1. The coprecipitation method was used to synthesize NP-Fe₃O₄@AC, which was characterized in terms of morphology (SEM), majority crystalline phase (XRD), chemical aspects (FTIR), and surface area (nitrogen sorption isotherms). The microplastic removal efficiency of NP-Fe₃O₄@AC was investigated as a function of initial concentration, contact time, and pH. The Sips equation and pseudo-second order model were the ones that best fit the experimental data of the isotherm and adsorption kinetics, respectively. NP-Fe₃O₄@AC removed 80% of the MPs at pH 6. From experimental observations (zeta potential, porosity, and SEM) and theoretical considerations, it was concluded that the mechanisms of hydrogen bonding, pore filling, and van der Waals forces were predominant in the removal of microplastics. The reuse tests indicated that NP-Fe₃O₄@AC could be reused up to five times, and the removal efficiency remained above 50%. These results indicate that NP-Fe₃O₄@AC is a viable alternative for possible applications aimed at removing microplastics from wastewater.

In Brazil, to this day, more than 70% of the rural population have little or no access to safe water. In this context, the household slow sand filter, or simply biofilter, is presented as an appropriate alternative for the water treatment for human consumption, since it presents relatively low cost and operational simplicity, and it can be built and operated with local material by the users themselves. The goal of the present work is to propose the project for a biofilter designed with adequate features to be implemented and used by families living in Brazilian rural areas, considering the easiness of construction and operation and the costs related to the production of the filter. Besides, this work is extended into a booklet and a spreadsheet, intended to spread this knowledge, making it accessible to the whole community. As a result, the proposed biofilter for a household of up to six people presented itself as an affordable option, with an initial cost of R$180,15, which can be even lower if containers available locally can be reused in the implementation of the system. Considering that it has been demonstrated by the literature to be technically feasible the construction and operation of biofilters by the local community itself, under technical supervision, it can be concluded that this is a viable alternative to make the access to safe water in rural areas possible. Moreover, it is expected that these results, combined with the free and wide propagation of these information in the booklet and the spreadsheet, can push public and private initiatives into investing in this kind of technology, going forward towards the universalizing the access to safe water.

Phosphorus (P) is an essential nutrient for being organisms; however, its presence in incompatible concentrations causes adverse effects on water bodies. Furthermore, P is a non-renewable resource employed in the industry and agriculture and may become depleted in the future. Thus, the potential for recovery P in wastewater has sparked significant scientific interest due to the dual benefit of reducing its discharge's impacts and recovering this nutrient. In this context, the current study aimed to assess P removal through adsorption using bimagnetic core@shell nanoadsorbents of the CoFe₂O₄@γ-Fe₂O₃ type, which allows for P removal and recovery. The effluent from the sludge dewatering centrifuge at the Brasília Norte Wastewater Treatment Plant, operated by Caesb, with an average concentration above 50 mg/L, exhibited the highest potential for P removal and recovery. Through the application of nanoparticles in bench-scale experiments, removal percentages of up to 35% were achieved in 180 minutes, maintaining the natural conditions of collected samples. The pseudo-second-order model exhibited the best fit to the experimental kinetic data, with a half-life time of around 4.64 minutes. It was observed that pH and the possible presence of interferents were the factors that most affected P adsorption when the natural effluent conditions were maintained. Nonetheless, the technology proved promising for the potential removal and recovery of P in real effluents, which can amount in Wastewater Treatment Plants exceeds several tons per year, as is the case with the Brasília Norte Wastewater Treatment Plant.

Every year, floods are responsible for causing natural disasters that have impacts on society. Changes in flood behavior are responses to conditions in the hydrographic basin, which can be altered by mechanisms of natural and/or anthropogenic origin. In flood frequency analysis, it is common to assume that historical series are stationary. However, significant changes in flood behavior increase interest in non-stationarity, including investigation of its existence, possible causes, and the degree of intensity of trends in the series. This interest leads to a debate on the incorporation and modeling of changes in flood analyses. This study presents a methodological approach to detect, model, and evaluate the non-stationary behavior of floods at local and regional levels. The approach involves analyzing the quantile frequency of floods using the Generalized Extreme Value (GEV) distribution applied to a stationary statistical model and three non-stationary models. Uncertainties associated with both flood quantiles and parameters of the non-stationary models, which are functions of time and other influential covariates in the study area, are evaluated. In the local analysis, a model selection among the four proposed models is made using the Bayesian Information Criterion (BIC) that best fits the historical series. To control the Type I error (false positives) at the regional level, the False Discovery Rate (FDR) is applied. In this study, an example of applying this methodological approach to 33 series of annual maximum streamflow in the Uruguay River Basin (RH), located in Brazil, is presented. By modeling the flood quantiles associated with potential change mechanisms (covariates) in the RH, in addition to Time, with a focus on large-scale climatic mechanisms such as El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), high rates of series that best fit the proposed non-stationary models were identified at the local level (21 to 91%). These rates also exist at the regional level, but in smaller proportions (0 to 88%), with changes in the 50-year flood quantiles ranging from 6% to 184% and exceedance probabilities ranging from 0% to 24%. These results contradict the stationarity scenario, highlighting the importance of nonstationary flood analysis at both local and regional levels, considering the associated uncertainties.

The Rainwater Harvesting Systems (RWHS) has been included in the New Legal Sanitation Framework approved in July 2020 as strategic alternative to reach universal water access. Despite the vast literature on assessing the feasibility of SAAC for households and establishments, there is lack of understanding on the impacts of this public initiative to water utilities. This work proposed and applied a methodology to evaluate the impact of RWHS dissemination on the performance of water utilities in the Federal District of Brazil. The methodology consisted of computing the potential water saving based on water balance of the RWHS for non-potable water demand, selecting and evaluating operational and economic indicators of the water utility performance and computing economic evaluation of different scenarios of RWHS dissemination. Results demonstrated that in most of the scenarios, the RWHS is not favorable to the water utility in terms of financial balance, mostly due to the loss of revenue given the reduction of water volume consumption. However, the financial balance has been improved by selling the saved water volume to other category of consumers, such as, commercial, industrial or public users. Additional consideration of environmental benefits of RWHS could also benefit the overall economic analysis of RWHS.

Considering the increase in Greenhouse Gas (GHG) emissions and the climatic consequences that bring the average global temperature closer to the limit agreed by the Paris Agreement for the year 2030, research on individuals' consumption patterns becomes relevant. A representative portion of emissions associated with domestic consumption by Brazilians is linked to the food category, and food consumption is closely related to the use of plastics as packaging for these items. Considering the consumer`s choice to use plastic bags for food packaging, this study aims to evaluate the effect of adopting behaviors on using single-use and returnable plastic bags in terms of GHG emissions, considering the reality of the Federal District (DF), Brazil. The estimate of GHG emissions was conducted through a Life Cycle Assessment (LCA) using data from the Ecoinvent 3.6 Cutoff base and operational data from the DF solid waste management authority. In parallel, behavior profiles were drawn on the consumption of single-use and reusable plastic bags by the population of the Federal District (DF), according to 391 responses obtained by a questionnaire based on the General Ecological Behavior (CEG) scale proposed by Kaiser and Wilson (2004). The results indicate that the population prefers to use only reusable bags (41%). In comparison, 15% of respondents were classified as strict users of single-use bags, associated with annual GHG emissions in the order of 0.38 kg CO₂-eq and 0.49 kg CO₂-eq, respectively. Emissions linked to the consumption of plastic bags are represented mainly in the production stage, with post-consumption solid waste management accounting for 7.3% (single use) and 1.8% (reusable) of total emissions per plastic bag analyzed. The consideration of other packaging alternatives, as well as the motivations of individuals for their choices, may complement the analysis in future investigations on the subject.

Riparian zones are areas adjacent to waterbodies and provide various environmental services, such as maintaining water quality and reducing surface runoff. In the Brazilian Forest Code, these areas are considered Permanent Preservation Areas (APPs). However, the inappropriate use of these spaces, with conversion for urban expansion and agricultural frontiers, has compromised their ecological integrity. Given the importance of these areas, the objective of this study was to analyze the influence of the integrity of the riparian zone of the Capão Comprido Stream Basin, in the Federal District, based on hydrosedimentological modeling, using the SWAT+ model and its new configurations. Initially, the model was calibrated and verified for flow and sediment discharge, with processing using QSWAT, SWAT Editor and SWAT Toolbox software. However, there were difficulties in calibrating and verifying the model using the SWAT Tollbox software. A simulation was carried out with the delimitation of landscape units (LSUs), to evaluate the impact of this new form of spatialization available in SWAT+ on the components of the water balance, flow and production of sediment and nutrient loads. The analysis of the influence of riparian zones on the referred items was carried out with simulations of five scenarios with different widths of the riverside zones. The scenarios were based on arts. 4th and 61-A of the Brazilian Forest Code. From the analysis of these aspects, it was supported that the hydrological modeling of river basins with the determination of landscape units, available in SWAT+, has the potential to improve the representation of river basins, by differentiating the characteristics of the hillslopes (uplands) from the riparian zone (floodplains), which allows more accurate simulations related to the physiography of the hydrographic units. These appreciated riverside areas are relevant for the conservation of water resources. As expected, the simulations confirmed that the increase in these areas contributed to the reduction in flow, surface runoff and the load of sediment and nutrients in the hydrographic basin. On the other hand, it contributed to the increase in subsurface runoff, percolation, return flow and deep aquifer recharge.

Cylindrospermopsin (CYN) is a toxic metabolite produced by several species of cyanobacteria. CYN can be dissolved in high proportions in aquatic environments, including water sources for human supply, thus representing a challenge for water treatment plants (WTPs). Therefore, it is necessary to use advanced drinking water treatment methods in addition to conventional systems. Amongst them, adsorption onto activated carbon (AC) has proven to be a promising and cost-effective alternative. So, the present work evaluated CYN adsorption onto two ACs with different acidic degrees. The adsorbents were synthesized as follows. Firstly, a starting mesopore-rich AC was prepared by chemical activation of coconut shells with H3PO4. Then, this AC was submitted to (i) treatment with HNO3, which gave rise to an AC rich in acidic oxygenated functional groups (ACOx); (ii) a heat treatment at 850 °C under an inert atmosphere, which rendered a much less acidic AC (ACHT). The kinetic tests were carried out in two study waters with different matrices: ultrapure water and ultrafiltered surface water from Lake Paranoá WTP (Brasília - DF). Equilibrium adsorption tests were carried out only in the ultrapure water matrix. The AC with the best performance in adsorption tests was also evaluated in the granular form through rapid small-scale column tests (RSSCTs). In both study waters, ACOx and ACHT fitted slightly better the pseudo-second-order model. Also, film diffusion was the limiting phase for toxin adsorption in the initial contact hours, followed by intraparticle distribution close to the equilibrium condition. The equilibrium adsorption data fitted the Langmuir isotherm model the better for both ACs. Despite its lower porosity and specific surface area, ACHT yielded better results in terms of kinetics and adsorption capacity (k2 ultrapure water = 0.0083 min-1; k2 ultrafiltered Lake Paranoá water = 0.025 min-1; qmax ultrapure water = 2.52 µg/mg). The RSSCT tests were conducted with ACHT in the ultrafiltered Lake Paranoá water matrix. The estimated breakthrough for a full-scale adsorption column was 28.4 days, for an initial toxin concentration of 15 µg/L and an empty bed contact time (EBCT) of 10 minutes.

Despite constituting a reduced portion of the global hydrological cycle, soil moisture is a key variable in the partitioning of precipitation among the other terrestrial hydrological processes. This is especially true in water limited environments, such as the Cerrado, in which the water-vegetation interaction seems to be defined especially by the availability of soil moisture compared to the energy available in the ecosystem. Therefore, understanding the impact of the land cover changes on soil moisture in these environments is one of the main challenges in the hydrology of Critical Zones - the portion of the Earth that extends from the vegetation canopy to the base of free aquifers. This challenge lies in the still limited knowledge of reference standards, derived from field data, which make it possible to analyze and predict how changes in native vegetation can affect the states and redistribution of precipitation in the Critical Zone and between it and the atmosphere. From this context, the aim of this thesis was to investigate subsurface hydrological processes and evapotranspiration, based on soil moisture patterns, and their relationship with the Cerrado predominant land cover and land use. This study included i) experimental, concentrated especially in twelve monitoring points installed at Fazenda Água Limpa (FAL/UnB); and ii) mathematical modeling stages at different spatial scales. Both were directed to the analysis of soil moisture and evapotranspiration in the Ribeirão do Gama watershed, a headwater predominantly covered by native Cerrado, located in the Distrito Federal, Brazil. Field data collection made it possible to estimate the energy and water balance in the vadose zone under native and altered vegetation, using equipments associated with turbulent fluxes towers, with an indication of increased control of soil moisture and reduction of evapotranspiration in the cerrado sensu stricto

in comparison with the eucalyptus plot (Eucalyptus urophylla x grandis). The in-situ monitoring also made it possible to evaluate the applicability of the direct current electric geophysical method as an alternative tool for monitoring moisture at different soil depths (up to 2.10 m deep). This evaluation resulted in the proposition and verification of a significant empirical model (p < 0.05) for estimating moisture from indirect measurements of soil electrical resistivity. Two-dimensional vertical sections derived from the empirical model showed the temporal behavior of moisture in the soil profile in accordance with field and water flow numerical simulation in porous media (FEFLOW) derived data. There were variations in the seasonal behavior of the moisture sections derived from the electrical resistivity in response to the characteristics of the native vegetation (“cerrado sensu stricto”: wooded cerrado; “campo limpo”: cerrado grassland; “campo sujo”: shrub cerrado; and gallery forest) and altered vegetation (eucalyptus and pasture). Finally, the incorporation of field data, obtained during the experimental stage, in the empirical (Budyko) and water balance (SWAT) hydrological modeling provided patterns of soil moisture and evapotranspiration, as well as a preliminary overview of the relationship between such patterns and the state factors of the Cerrado (land use and cover, pedology and slope). In addition, the study made it possible to structure a hydroclimatological monitoring network that will support further investigations regarding the effects of soil cover on the spatial and temporal variability of soil moisture. It is recommended to expand the spatial and temporal representativeness of field data directed to the soil moisture - evapotranspiration relation; to improve the analysis of state factors in soil moisture, especially through detailed pedological characterization, and to continue the assimilation of field and remote sensing data in the parameterization of watershed scale hydrological models.

Plastics are materials that are present in various activities in everyday life. Plastic waste, in turn, has been found in several cleaning actions around cities. PET bottles are one of the most found items in this type of activity. Proposing new alternatives for managing PET waste is urgent, not only because of the pollution impacts but also because of the climate impacts and the extraction of resources for its manufacture. In the Federal District, 19 Mg of PET waste are produced annually, sent for recycling as bottle-to-fiber (B2F) to be incorporated mainly in the textile industry. Through the Life Cycle Analysis application, the impacts of abiotic resources depletion and climate change related to production and final disposal towards the end-of-life of the DF soft drink PET bottle were evaluated. The study characterized the current scenario of the soft drink PET bottle, i.e., evaluated the current PET production model and its post-consumption destination, evaluating alternative proposals to achieve better environmental performance. The results indicated that adopting returnable PET bottles has a higher potential for impact mitigation. Considering the annual production of soft drinks in DF, around 11,610 tons of CO2 eq and 68,400 kilograms of Sbeq can be avoided annually. The most significant impacts are associated with transportation for waste collection, which should be optimized to obtain better environmental performance, i.e., lower impacts. It is recommended that future studies evaluate and compare other treatment technologies as management options for PET waste, such as chemical recycling, which has been growing and becoming more feasible in recent years. Further research should focus on evaluating other soft drink packaging materials, such as aluminum cans and glass bottles, compared to PET bottles.

The development of agricultural activities is directly linked to natural resource availability and is continually affected by climate instability and water scarcity events. The improper use of rural areas, the suppression of native vegetation, and the inadequate and outdated management practices influence the watershed hydrological behavior. Soil and water management and conservation practices are considered potential technical alternatives to help the continuation, improvement, and evolution of sustainable agricultural activity. The objective of this study was to analyze how land use change and the application of techniques and practices of management and conservation of water and soil influence the water balance and the quality of water resources, considering two predominantly rural watersheds and contributors to the main water public reservoir in the Federal District (Descoberto Reservoir): Capão Comprido stream and the Rodeador stream watersheds. Therefore, the study relied on the characterization of four land-use scenarios in the region, that address the beginning of the agricultural occupation, with the construction of Brasília (Brazil's capital), until the most current occupation model. The SWAT+ database was parameterized and adapted to the rural context of the region, with the addition of information related to fertilizers, agricultural implements, soil conservation practices, and irrigation management adjusted to the local reality. Modeling was performed for the four land-use scenarios, relying on sensitivity analysis of 10 parameters and automatic calibration based on observed daily flow data. Calibration was chosen for the Capão Comprido watershed, which was replicated in the Rodeador watershed after. The Nash-Sutcliffe efficiency coefficients (NSE), coefficient of determination (R²), and PBIAS were used, but they were not considered satisfactory for all scenarios regarding calibration and verification. The hydrologic modeling of the changes in influences on land use, water, and soil conservation practices, was carried out with the simulation of the most current land use scenario, correlating the adoption of conventional management practices and conservationist practices. It was found that with the use of conservation practices, the Capão Comprido and Rodeador watersheds responded to the decrease of sediments carried, increased percolation and infiltration in the soil, and, consequently, greater regularity in the water regime of the watershed.

ABSTRACT The characterization of diffuse pollution in a catchment refers to the proper measurement of runoff water quality (WQ) along with hydrological data of rainfall and flow. Planning experimental monitoring is one of the major issues for evaluating this type of pollution (KOZAK, 2020). The objective of this thesis is to evaluate methods and techniques that lead to the identification of the generation processes of diffuse pollution in drainage catchments through monitoring in a single location, the outflow of the contribution area. This monitoring strategy was adopted in three urban catchments in the Federal District, CO, RFI and VP, chosen due to the characteristics of land use, carrying out hydrological monitoring (pluviometry and fluviometry) and water quality monitoring in these areas. With this data acquisition, it was possible to analyze the diffuse pollution with pollutograms, the determination of EMC and first flush, statistical analysis of the VP region; the hydraulic-hydrological modeling for quantitative analysis using SWMM (rainfall-discharge and implementation of mitigation practices) in the RF I region; comparison of the diffuse pollution data of the three study areas, with emphasis on land use and occupation issues, and finally the water quality modeling using the Unit Load model (pollutogram simulation). SWMM adequately simulated the runoff from RF I after calibration, however the modeling was still impaired due to problems in monitoring large flows. The analysis of WQ in the VP allowed the identification of sewage discharges (found during the drought period) and the most critical pollutants related to diffuse pollution, which are solids and organic matter. The Unit Load model can be considered a suitable tool for estimating pollutograms during long events in order to optimize monitoring resources. However, for the prediction of diffuse pollution generation, it proved to be deficient due to the diverse interaction of the pollutant build up and wash off processes along the catchment. This thesis made it possible to understand that monitoring for studies on diffuse pollution carried out in the outfall is adequate for the stormwater management in the catchment, as it is concise and efficient, and allowed the identification of the influence of land use and occupation processes, such as domestic sewage discharge, construction works and availability of adequate sanitary infrastructure, supporting the proposition of urban solutions for the reduction of this type of loads in the receiving water bodies.