Ocorrência de compostos de interesse emergente no aquífero Dunas-Barreiras e nos esgotos de Natal/RN

The detection of emerging interest microcontaminants in environmental samples of surface water, groundwater, drinking water, wastewater and effluents from water and sewage treatment plants (WTP and STP), in many countries, suggests these pollutants are widespread in the environment, mainly in urban areas. This is a reason for great concern, since many of these compounds are potentially harmful for humans other living beings, and they are not efficiently removed in the majority of WTP and STP, which is exacerbated by precariousness of water supply and sanitation services. In Natal, like other Brazilian cities, the sewage system serves only part of the urban area (about 30%), so that the rest of the wastewater is infiltrated in the sandy soil of the region in cesspool-dry well systems. This has resulted in contamination of groundwater in the area (sand-dune barrier aquifer, which supplies more than 50% of the city population), which has been observed by the increase in nitrate concentration in supply wells. The vulnerability of the sanddune barrier aquifer, combined with reports of the presence of emerging interest microcontaminants in Brazil and worldwide, led to this research, which investigated the occurrence of fifteen microcontaminants in Natal groundwater and sewage. Samples were collected at five wells used for water supply, the raw sewage and the effluents from biological reactors from STP (UASB and activated sludge reactors). Two samples of each sample were taken, with one week apart between the samples. To determine the contaminants, extraction of aquifer water, and raw and treated sewage samples were performed, through the technique of using SPE Strata X cartridge (Phenomenex®) to the aquifer water, and Strata SAX and Strata X (Phenomenex® ) for samples of raw and treated sewage. Subsequently the extracts were analyzed using GC-MS technique. Much of the analyzed microcontaminants were detected in groundwater and sewage. The concentrations in groundwater are generally lower than those found in the sewers. Some of the compounds (estrone, estradiol, bisphenol A, caffeine, diclofenac, naproxen, paracetamol and ibuprofen) are partially removed at STP.

Influência da pressão e da vazão de concentrado sobre o desempenho de ultrafiltração no pós-tratamento de esgotos

Despite the numerous advantages resulting from the use of membrane filters technology, intrinsic limitations fouling process become relevant to its applicability. The control of operating conditions is an important tool to mitigate fouling and achieve good levels of efficiency. In this sense, the objective of this study was to investigate the effect of transmembrane pressure and concentrate flow in the performance of ultrafiltration, applied to the post-treatment of domestic sewage. The process was evaluated and optimized by varying the pressure (0.5 and 1.5 bar) and the concentrate flow (300 and 600 L/h), using a 22 factorial design, in order to investigate the effects on the permeate flow and quality of effluents generated at each operating condition. We evaluated the following quality indicators for permeate: pH, electrical conductivity, total suspended solids, turbidity, calcium and Chemical Oxygen Demand (COD). In all tests, we observed marked reduction in the permeate flux at the early stages, followed by a slow decline that lasted until it reaches a relatively constant level, around 120 minutes of filtration. The increased pressure resulted in a higher initial permeate flux, but the decrease of the flow with time is greater for tests at higher pressure, indicating a more pronounced fouling process. On the other hand, increasing the concentrate flow resulted in a slower decline in permeate flux with the filtration time. Regarding the quality of permeate, the transmembrane pressure of 0,5 bar was the one that allowed better results, and was statistically confirmed through the two-way ANOVA test with repeated measures, significant effect of pressure on the turbidity of the permeate. The concentrate flow, in turn, showed no significant influence on any of the quality parameters. Thus, we conclude that, from an economic and environmental point of view, it is more interesting to operate ultrafiltration membrane system with a lower concentrate flow associated with a low transmembrane pressure, since under these conditions will produce less waste, and the permeate will present lower concentrations of the analyzed constituent, especially lower turbidity.

SISTEMA DE INDICADORES E DESIGUALDADE SOCIOAMBIENTAL INTRAURBANA DE SÃO LUÍS-MA; BRASIL

Aplicação de um sistema de indicadores intraurbano à cidade de São Luís para mensurar a sua desigualdade socioambiental. O sistema de indicadores foi dividido em quatro dimensões: Habitabilidade, Saneamento, Educação e Renda. Para compor as dimensões, foram utilizados os dados secundários do censo IBGE/2000, desagregados ao nível dos 780 setores censitários de São Luís (MA). A análise estatística dos dados foi fundamentada em técnicas multivariadas, a saber: Análise Fatorial (AF) e Análise de Clusters (AC). Para representação cartográfica das desigualdades foram confeccionados mapas através do programa ArcGIS versão 9.3. As desigualdades intraurbanas revelaram grandes discrepâncias quanto aos indicadores de acesso ao serviço de coleta de esgotos, seguido do serviço de coleta de resíduos sólidos e abastecimento de água. A dimensão renda do responsável foi o tópico que revelou a maior discrepância em relação às demais dimensões avaliadas. Através do sistema de indicadores intraurbanos, concluiu-se que espaço urbano é social e ambientalmente desigual.  

O USO DO SOLO E A QUESTÃO AMBIENTAL NA REGIÃO SUDOESTE DA BAHIA - BRASIL

A Região Sudoeste da Bahia tem uma área total de 42.542,9 km², sendo composta de 39 municípios, com uma população de 1.143.947 habitantes. Abrange expressiva diversidade geoambiental, com trechos da Mata Atlântica, Caatinga e diversas formações intermediárias. Essa pesquisa tem como objetivo analisar o uso dos recursos naturais e a problemática ambiental na Região. A área possui características facilitadoras dos processos erosivos em decorrência dos seguintes aspectos: topografia acidentada; elevada erodibilidade e erosividade e pequeno poder de proteção exercida pela cobertura vegetal. A ocupação territorial esteve fortemente vinculada a pecuária, em que mais de 60% das terras da região são ocupadas com pastagens, na atualidade. Os mapeamentos e os levantamentos de campo permitiram identificar como principais problemas e conflitos socioambientais: a compactação dos solos nas áreas de pecuária, erosão e depauperamento nas áreas de agricultura de subsistência, contaminação do solo e da água nas áreas irrigadas, contaminação dos recursos hídricos pelos esgotos urbanos e uso de agrotóxicos, degradação ambiental pelas atividades mineradoras, queimadas e descontrole na destinação e tratamento dos resíduos sólidos. A busca de solução de tais conflitos implica no necessário envolvimento de cada município na sua superação, perpassando também pelos possíveis consórcios municipais.