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.

Potencialidade do tratamento eletroquímico oxidativo associado à adsorção para remediação de corantes têxteis

This study aimed to evaluate the potential of oxidative electrochemical treatment coupled with adsorption process using expanded perlite as adsorbent in the removal of textile dyes, Red Remazol and Novacron Blue on synthetic effluent. Dyes and perlite were characterized by thermogravimetry techniques (TG), Differential Scanning Calorimetry (DSC), Spectroscopy infrared (IR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. Electrochemical treatments used as anodes, Ti/Pt and Pb/PbO2 under different conditions: 60 minutes, current density 20, 40 e 60 mAcm-2, pH 1, 4.5 e 8 and temperature variation 20, 40 e 60 ºC. In the case of adsorption tests, contact time of 30 minutes for the Remazol Red dye and 20 minutes for Novacron Blue were established, while pH 1, 4.5 e 8, 500 mg adsorbent and temperature variation 20, 40 e 60 ºC were used for both treatments. The results indicated that both treatments, electroxidation/adsorption and the adsorption/electroxidation, were effective for removing color from synthetic solutions. The consumption of electricity allowed to evaluate the applicability of the electrochemical process, providing very acceptable values, which allowed us to estimate the cost. Total organic carbon (TOC) and Gas Chromatography linked mass spectrometer (GC-MS) analyzes were performed, showing that the better combination for removing organic matter is by Pb/PbO2 and perlite. Meanwhile, GC-MS indicated that the by-products formed are benzoic acid, phthalic acid, thiocarbamic acid, benzene, chlorobenzene, phenol-2-ethyl and naphthalene when Remazol Red was degraded. Conversely, aniline, phthalic acid, 1, 6 - dimethylnaphthalene, naphthalene and ion hidroxobenzenosulfonat was detected when Novacron Blue was studied. Analyses obtained through atomic absorption spectrometry showed that there was release of lead in the electrochemical oxidation of analyzes that were performed with the anode Pb/PbO2, but these values are reduced by subjecting the effluent to adsorption analysis. According to these results, sequential techniques electroxidation/adsorption and adsorption/electroxidation are to treat solutions containing dyes.