Aníbal da Fonseca Santiago

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.

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.

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.

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.

Identificação de áreas alternativas para disposição de resíduos sólidos na região do Baixo Ribeira do Iguape - SP

This paper addresses the proposition of scenarios for the equation of the disposal of solid residues generated by urban areas of the region of the Baixo Ribeira de Iguape, located in the Sao Paulo State, Brazil. Multicriterion analysis requiring identification of criteria that can play restrictions and factors roles were used. Aggregation Criteria was represented by the Weighed Linear Combination and the Ordered Weighed Mean. For each one of the selected cities it was calculated the required area for the final disposal of its solid residues. The results had shown that the best area for the city of Cajati is located approximately 3,0 km of its headquarters, for Jacupiranga 2,7 km and for Pariquera-Acu 2,4 km. The applied methodology revealed adequate to the objective of this research, taking into account 18 influential factors and restrictions in the decision process.

Biodiesel from wastewater: lipid production in high rate algal pond receiving disinfected effluent

The production of different species of microalgae in consortium with other micro-organisms from wastewaters may represent an alternative process, to reduce the costs, for obtaining biofuels. The aim of this study was to evaluate the influence of pre-ultraviolet disinfection (UV) in the production of lipids from biomass produced in high rate ponds. Two high rate algal ponds were evaluated: a pond that received domestic sewage without disinfection and the other receiving domestic sewage previously disinfected by UV radiation (uvHRAP). The UV disinfection did not lead to significant differences in fatty acid profile and total lipid productivities, although it increased algal biomass concentration and productivity as well as lipid content. Moreover, the overall biomass concentrations and productivities decreased with the UV disinfection, mostly as a consequence of a loss in bacterial load. We thus conclude that uvHRAP disinfection may represent a potential strategy to promote the cleaner and safer growth of algal biomass when cultivated in consortium with other micro-organisms. Mainly regarding the use of wastewater as culture medium, together with a cheaper production of lipids for biodiesel, pre-disinfection may represent an advance since extraction costs could be significantly trimmed due to the increase in lipid content.