This paper aimed to analyze the reduction in the ballast layer permeability simulated in a laboratory in saturated conditions by the presence of rock dust as a contaminant of three types of rocks explored in different deposits in the northern region of the state of Rio de Janeiro, Brazil, through laboratory testing relating the physical properties of rock particles before and after sodium sulfate attack. Sodium sulfate attack is justified by the proximity of some sections of the planned EF-118 Vitória-Rio railway line to the coast and of the sulfated water table to the ballast bed, which could degrade the material used and compromise the railway track. Granulometry and permeability tests were performed to compare ballast samples with fouling rates of 0, 10, 20, and 40% rock dust by volume. A constant head permeameter was used to analyze hydraulic conductivity and establish correlations between the petrography and mercury intrusion porosimetry of the rocks, namely two types of metagranite (Mg1 and Mg3) and a gneisse (Gn2). Rocks, such as Mg1 and Mg3, with a larger composition of minerals susceptible to weathering according to petrography analyses, tend to be more sensitive to weathering tests. This, in conjunction with the climate in the region studied, with average annual temperature and rainfall of 27 °C and 1200 mm, could compromise track safety and user comfort. Additionally, the Mg1 and Mg3 samples showed greater percentage variation in wear after the Micro-Deval test, which could damage the ballast due to the considerable changeability of the material. The mass loss caused by abrasion due to the passage of rail vehicles was assessed by the Micro-Deval test, with Mg3 (intact rock) declining from 8.50 ± 1.5 to 11.04 ± 0.5% after chemical attack. However, Gn2, which exhibited the greatest mass loss among the samples, showed no significant variation in average wear, and its mineralogical characteristics remained almost unchanged after 60 sodium sulfate cycles. These aspects, combined with its satisfactory hydraulic conductivity rate, indicate that Gn2 is suitable for use as railway ballast in the EF-118 railway line.

The use of treated domestic effluent in agriculture is important not only as a source of water but also as a source of nutrients for crops. In this context, the objective of this study was to evaluate its use for the production of ornamental sunflower cv. ‘Anão de Jardim’ in a bench-type low cost hydroponic system, inferring on its technical feasibility and observing the possible impacts on the crop. The experiment was carried out in a greenhouse adopting a completely randomized design with four treatments (T1 - nutrient solution of Furlani 100%, prepared in municipal supply water - control), T2, T3 and T4 - nutrient solution of Furlani, respectively, with 100, 75 and 50% strength, prepared in treated domestic effluent and six replicates, totalizing 24 experimental units, each consisting of 15 plants. All treatments met the nutritional requirements of the plants and presented adequate contents of N, P, K, Ca and Mg in leaf and stem at harvest leading to satisfactory plant growth and produced acceptable commercial grade chapters and stems. The plants under treatment T4 although produced chapters of commercial quality but exhibited great variability in comparison to the other treatments, therefore except this treatment any other treatment can be used for hydroponic production of ornamental sunflower utilizing treated domestic effluents.