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Leakage of transformer dielectric fluids is a concern because it may pose a risk of environmental contamination. In this study, the deleterious effects of vegetable and mineral dielectric fluids in water bodies were investigated using biodegradability and acute toxicity tests with Danio rerio and Artemia salina. Regarding biodegradability, all four tested vegetable oils (soy, canola, sunflower and crambe) were considered as easily biodegradable, presenting degradation rates significantly higher than the Lubrax-type mineral fluid. Acute toxicity tests were performed in two separate experiments without solution renewal. In the first experiment, the organisms were exposed in direct contact to different concentrations of vegetable (soy) and mineral (Lubrax) oils. Total soy-type vegetable oil has a higher toxic effect than Lubrax-type mineral oil. In the second experiment, the organisms were exposed to increasing percentages of the water-soluble fraction (WSF) of both types of tested oils. The LC values for the water-soluble fraction of the Lubrax-type mineral oil were about 5 and 8% for the Danio rerio and Artemia salina bioindicators, respectively, whereas the vegetable oil did not present toxic effect, regardless of its WSF. These results have shown that a strict selection of dielectric fluids and monitoring the leakage from power transformers is a serious duty of environmental protection agencies.

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This study aimed to evaluate the crude glycerol efficiency, from biodiesel production, biogas production with co-digestion of swine manure. The process was conducted with several concentrations of glycerol 0, 5, 10, 20, 30 and 40% (w/w) and swine manure with a concentration of 20, 40 and 60% (w/w) with pH 7.2 and 35°C. The fermentation periods were 21 and 30 days. Fifty ml of micro-reactors were used airtight coupled to a 10 ml syringe best condition to evaluate the production of biogas. Analysis was also performed to evaluate total solids reduction of solids mass in proposed treatments. Using a digestion system on a laboratory scale, is constituted by a 20 L reactor total volume, a gas meter and a reservoir for storage thereof, biogas production was evaluated for the sample with 5% of glycerol and the control sample (0% glycerol). With the aid of a gas chromatograph analyzed the methane content thereof. It was observed that the amount of swine manure has great influence on the production of biogas and the concentration in the sample yield was better with 60%. The crude glycerol together to swine manure at a rate of 5% w/w can be used as a supplement in anaerobic digestion, providing a significant increase in the production of biogas in its content of methane and removal of total solids. Moreover, it has been found that concentrations of 20, 30 and 40% (w/w) of glycerol were inhibitory at all studies, difficulties occur and little production of biogas. Chromatographic analysis of the sample with 5% glycerol was satisfactory in relation to methane content, showing 58.87% of CH4 in the biogas.