Performance evaluation of a photo-Fenton process applied to pollutant removal from textile effluents in a batch system.

In this work, the performance of a photo-Fenton process-based textile effluent treatment was investigated using both solar and artificial light sources. A full 3(3) factorial experimental design was applied for the optimisation with respect to three parameters: initial pH, amounts of Fe(2+) (0.01-0.09 g L(-1)) and H(2)O(2) (1-7 g L(-1)). The photo-Fenton process response was evaluated on the basis of chemical oxygen demand (COD) removal and decolourisation. The optimum conditions of the photo-Fenton process were attained at concentration values of 0.05 g Fe(2+) L(-1) and 6.0 g H(2)O(2) L(-1) and pH 3, for both solar and artificial light sources. The effects of initial pH, and Fe(2+) and H(2)O(2) concentrations were evaluated. From the monitoring of TOC, COD, turbidity and decolourisation over time, the progress of the mineralisation of dyes was analysed, forming nitrate, ammonia nitrogen and nitrite. Low amounts of residual peroxide and iron, which were below the limit allowed by Brazilian environmental legislation, were attained after 360 min of irradiation time for both artificial and solar sources. An operational cost of US$ 6.85 per m(3) of treated effluent was estimated using solar irradiation.

Analysis of metal concentration levels in water, sediment and fish tissues from Toledo municipal lake by applying SR-TXRF technique.

The main objective of this study was to evaluate the metal content in water and sediment from the Toledo municipal lake, as well as the concentration levels of heavy metals in muscle and liver of four fish species. A digestion procedure was performed in all fish samples. Metal analysis was performed by using the Synchrotron Radiation X-ray Fluorescence technique. The accuracy and validity of the measurements were determined by analysis of certified reference materials. The highest Cr, Cu and Se concentration levels above the maximum tolerance limit according to the Brazilian norms in fish tissue could be associated with the metal uptake and accumulation due to the direct contact with contaminated water and sediment.

Inhibition effect on the Allium cepa L. root growth when using hexavalent chromium-doped river waters.

The effect of Cr(6+) on Allium cepa root length was studied using both clean and polluted river waters. Seven series of Cr(6+)-doped polluted and non-polluted river waters were used to grow onions. Chromium concentration (Cr(6+)) of 4.2 mg L(-1)(EC(50) value), doped in clean river water caused a 50% reduction of root length, while in organically polluted samples similar root growth inhibition occurred at 12.0 mg Cr(6+) L(-1). The results suggested that there was a dislocation to higher values in toxic chromium concentration in polluted river water due to the eutrophization level of river water.

Evaluation of trace element levels in muscles, liver and gonad of fish species from São Francisco River of the Paraná Brazilian state by using SR-TXRF technique.

This study is focused on the analysis of an accumulation of inorganic elements in muscles, liver and gonad of seven fish species from São Francisco River located in the Paraná state of Brazil. Concentrations of the elements were determined using the SR-TXRF technique. In the muscles of fish species, negative length dependent relationships were observed for chromium and zinc ion absorption. The obtained results showed that accumulated Cr ions values are above the limits defined in the Brazilian legislative norm on food.