Maria Lúcia Calijuri

Evaluation of the Influence of Natural and Antrhopogenic Processes on Water Quality in Karstic Region

This paper presents a comprehensive study on the quality of surface and groundwater in an environmentally sensitive karstic watershed strongly pressed by urban growth. The objective of the study was to assess the integrated effects of human activities and natural characteristics of karstic environments on the quality of surface and groundwater using multivariate statistical techniques. Data from 18 physical, chemical, and microbiological water quality variables obtained throughout a hydrological year were analyzed using principal components analysis (PCA) and cluster analysis. The PCA was carried out individually for surface water and groundwater. Our goal was to study the behavior of the water quality variables at each of these systems, as well as to infer the importance of these variables on the dynamics of the water resources in the region. Our results for surface water showed that the 18 original variables could be reduced to five principal components which together accounted for 69% of the total variation in the data, whereas for groundwater, 70% of the total variation in the data was explained by five principal components. In order to evaluate the impacts of anthropic activities on the water quality at the monitoring locations, the cluster analysis was applied to the ten sampling points. The analysis identified five clusters, two of which are formed by points with low contamination levels and three where the anthropic interference is noticeable. The results suggest the existence of specific contamination sources in many points, including in the groundwater, and highlight the natural vulnerability of the karstic environments.

Algal biomass production and wastewater treatment in high rate algal ponds receiving disinfected effluent

Algal biomass production associated with wastewater is usually carried out in high rate algal ponds (HRAPs), which are concomitantly used in the treatment of such effluent. However, most types of wastewater have high levels of bacteria that can inhibit the growth of algal biomass by competing for space and nutrients. The objective of this study was to assess the influence of ultraviolet (UV) pre-disinfection on the performance of HRAPs used for wastewater treatment and algal biomass production. Two HRAPs were tested: one received effluent from an upflow anaerobic sludge blanket (UASB) reactor – HRAP – and the second received UASB effluent pre-disinfected by UV radiation – UVHRAP. Physical, chemical and microbiological parameters were monitored, as well as algal biomass productivity and daily pH and dissolved oxygen (DO) variation. The UVHRAP presented highest DO and pH values, as well as greater percentage of chlorophyll a in the biomass, which indicates greater algal biomass productivity. The average percentages of chlorophyll a found in the biomass obtained from the HRAP and the UVHRAP were 0.95±0.65% and 1.58±0.65%, respectively. However, total biomass productivity was greater in the HRAP (11.4 gVSS m−2 day−1) compared with the UVHRAP (9.3 gVSS m−2 day−1). Mean pH values were 7.7±0.7 in the HRAP and 8.1±1.0 in the UVHRAP, and mean values of DO percent saturation were 87±26% and 112±31% for the HRAP and the UVHRAP, respectively. Despite these differences, removal efficiencies of organic carbon, chemical oxygen demand, ammoniacal nitrogen and soluble phosphorus were statistically equal at the 5% significance level.

Tratamento de esgotos sanitários em sistemas reatores UASB/wetlands construídas de fluxo horizontal: eficiência e estabilidade de remoção de matéria orgânica, sólidos, nutrientes e coliformes

This work presented the results of a 19-month study on the performance of constructed wetlands in terms of organic matter, solids, nutrients and coliforms removal in pilot scale unities with horizontal, subsurface and surface flow, with hydraulic retention time from 1.3 to 5.3 days, as post-treatment of UASB effluents (domestic wastewater). Organic matter and solids were effectively and consistently removed, with average values of 70, 80 and 60% for TSS, BOD5 and COD, respectively. Nutrients removal, after a promising start up, became unstable and apparently influenced by temperature. The treatment system has also shown high potential to remove coliforms, although with relatively wide variations over the study period: ≈ 2 log10 reduction of total coliforms and 2-4 log10 reduction of Escherichia coli.

Análise de sensibilidade e calibração do modelo SWAT aplicado em bacia hidrográfica da região sudeste do Brasil

Estimates of water and soil losses have been carried out worldwide, using empirical or conceptual models, such as SWAT (Soil and Water Assessment Tool). SWAT, widely used to predict the impact of changes in soil use and management on soil loss and stream flow rate, is extremely sensitive to the quality of input data. Consequently, prior to an application of the model, a sensitivity analysis is required to deal more carefully and with more precision with certain data, reducing the uncertainty and increasing the reliability of the results. Although a slow process, calibration is indispensable to ensure that the simulation results are comparable to the field data. A successful application of the model in this area, with no previous soil and water studies, allows an extrapolation of the results to watersheds with similar characteristics. In this study, a sensitivity analysis and SWAT calibration were carried out with data from 10 plots outlined in the Watershed Sao Bartolomeu, in southeastern Brazil. The results were satisfactory, according to the coefficient of efficiency of Nash and Sutcliffe (COE), used to evaluate the model performance; the COE was 0.808 for sediment yield and 0.997 for the stream flow rate, indicating well-calibrated models. Sensitivity analysis was not influenced by a higher or lower discretization of the watershed, which facilitated the analysis process. The sensitivity of the parameters varied according to the use and soil cover in each sub-watershed, and cannot be generalized, that is, the characteristics of the sub-watersheds influence the parameter sensitivity.

Post-treatment of UASB reactor effluent in waste stabilization ponds and in horizontal flow constructed wetlands: a comparative study in pilot scale in Southeast Brazil.

The results of a 20-month period study in Brazil were analyzed to compare horizontal-flow constructed wetlands (CW) and waste stabilization pond (WSP) systems in terms of land area requirements and performance to produce effluent qualities for surface water discharge, and for wastewater use in agriculture and/or aquaculture. Nitrogen, E. coli and helminth eggs were more effectively removed in WSP than in CW. It is indicated that CW and WSP require similar land areas to achieve a bacteriological effluent quality suitable for unrestricted irrigation (10(3) E. coli per 100 mL), but CW would require 2.6 times more land area than ponds to achieve quite relaxed ammonia effluent discharge standards (20 mg NH(3) L(-1)), and, by far, more land than WSP to produce an effluent complying with the WHO helminth guideline for agricultural use (< or =1 egg per litre).

Estudo de indicadores de saúde ambiental e de saneamento em cidade do Norte do Brasil

The quality of life from a population is directly related to urban infrastructure on which it is embedded. Accordingly, the objective of the study was to evaluate the public health in the municipality of Tucurui in Parana, under conditions of environmental sanitation to the composition of a system with a smaller number of variables to discriminate areas with different levels of sanitary and environmental health, and relate these indicators with the occurrence of diseases related to health in these areas. The municipality of Tucurui was selected for the study area due to the deficiency of their health infrastructure, high rate of population growth, and high incidence of tropical diseases directly related to the health conditions.

Multicriteria analysis applied to landslide susceptibility mapping

Current human settlements are characterized by disorganized urbanization and high population densities, which can impact the landscape and the environment. Soil transport leads to erosion and aggradation of water bodies and increases landslide susceptibility in regions with more uneven topographies. Landslides are the most common environmental accidents and have caused the most deaths; one example is the incident that occurred in the mountainous region of the state of Rio de Janeiro (Brazil) in January 2011. Mapping the predisposition or susceptibility of components of the physical environment to landslides provides an integrated view of the characteristics and physical processes that act within a region. Therefore, the objective of this study is to evaluate the urban expansion proposal of Baptista (Avaliação da suscetibilidade aos movimentos de massa, erosão e escoamento superficial em Nova Friburgo, RJ, 2009) and compare it with the areas affected by the mega-disaster of 2011 using hierarchical decision analysis and a GIS toolkit. The results show that landslides did not affect the areas selected for urban expansion, i.e., the method was useful for identifying the areas that were most susceptible to landslides prior to the disaster.

Impact of land use/land cover changes on water quality and hydrological behavior of an agricultural subwatershed

Knowing the influence of land use/land cover changes on the hydrological behavior of a subwatershed is essential to land use planning. The Alto Paraguaçu Watershed is a major producer of fruits and vegetables, and currently the largest producer of English potato in the north/northeast of Brazil. The water availability in the region can be considered the limiting factor to the expansion of agricultural frontiers. Therefore, in order to assess the influence of land use/land cover on the quality and quantity of the water resources in the subwatershed, three sampling campaigns were carried out (two in the rainy season and one in the dry season) at ten points throughout the watershed, as well as the hydrological analysis and land use/land cover changes assessment for both seasons. The objective was to relate land use/land cover indicators with hydrological indicators in order to fit a model to predict water changes in the studied subwatershed. The results showed that the changes that occurred in land use/land cover for the development of the current agriculture have significantly impacted the hydrological behavior in the Alto Paraguaçu watershed. It was possible to observe that the quality and quantity of water were directly influenced by the anthropization process. This study highlights the importance of suitable land use/land cover for the conservation of water resources.

Effect of solar radiation on the lipid characterization of biomass cultivated in high-rate algal ponds using domestic sewage

The objective of this paper is to compare the lipid content and composition of biomass produced by a consortium of microalgae and bacteria, cultivated under different solar radiation intensities and tropical conditions in pilot-scale high-rate ponds (HRPs) using domestic sewage as culture medium. The treatment system consisted of an upflow anaerobic sludge blanket reactor followed by UV disinfection and six HRPs covered with shading screens that blocked 9%, 18%, 30%, 60% and 80% of the solar radiation. The total lipid content does not vary significantly among the units, showing a medium value of 9.5%. The results show that blocking over 30% of the solar radiation has a negative effect on the lipid productivity. The units with no shading and with 30% and 60% of solar radiation blocking have statistically significant lipid productivities, varying from 0.92 to 0.96 g m−2 day−1. Besides radiation, other variables such as volatile suspended solids and chlorophyll-a are able to explain the lipid accumulation. The lipid profile has a predominance of C16, C18:1 and C18:3 acids. The unsaturation of fatty acids increases with the reduction in solar radiation. On the other hand, the effect of polyunsaturation is not observed, which is probably due to the presence of a complex and diverse biomass.

Regionalização de vazões com base em modelo digital de elevação para a bacia do Rio Paraíba do Sul

The stream-flow regionalization is made in locations where the hydrologic information is not available, however the determination of the physical characteristics to each place of interest considerably limits the application of the results of a conventional study of the stream-flow regionalization. One of the solutions for this problem is the automation of the process using a hidrologically consistent digital elevation model (HCDEM). The main objective of this paper was the regionalization of the mean, maximum and minimum stream-flow in South Paraiba River using a HCDEM. The duration curve also was regionalized. The digital elevation model was shown hidrologically consistent making possible the automation of the process to estimate the physical characteristics. Four hidrologically homogeneous areas were identified for this studied area and the regression equations were obtained. The drainage area and the length of the main river were the most important variables to represent the regionalysed functions.