Ensaios de piezocone em um depósito de argila mole da cidade do Recife

Piezocone tests been been performed in a soft clay deposit at Recife using the equipment developed at COPPE/UFRJ. Laboratory tests have also been performed. Piezocone test results have been compared with laboratory test results, as well as with data from other deposits. The comparison between piezocone and laboratory tests have shown a good agreement for many soil parameters.Foram realizados ensaios de piezocone em um depósito argiloso mole da Cidade do Recife com o equipamento desenvolvido na COPPE/UFRJ. Os resultados obtidos foram comparados com dados de outras argilas como também com resultados de laboratório obtidos em campanha realizada neste trabalho. A comparação dos dados apresentou uma boa concordância de uma maneira geral entre resultados de campo e laboratório para diversos parâmetros geotécnicos

Application of Green Surfactants in the Remediation of Soils Contaminated by Hydrocarbons

none6siarticolo in formato elettronico n. 1666Among the innovative technologies utilized for the treatment of contaminated soils, the use of green surfactants appears to be a biocompatible, efficient, and attractive alternative, since the cleaning processes that normally use synthetic surfactants as additives cause other problems due to toxicity and the accumulation of by-products. Three green surfactants, i.e., two biobased (biobased 1 and biobased 2) surfactants produced by chemical synthesis and a microbial surfactant produced from the yeast Starmerella bombicola ATCC 22214, were used as soil remediation agents and compared to a synthetic surfactant (Tween 80). The three surfactants were tested for their ability to emulsify, disperse, and remove different hydrophobic contaminants. The biosurfactant, which was able to reduce the water surface tension to 32.30 mN/m at a critical micelle concentration of 0.65 g/L, was then used to prepare a commercial formulation that showed lower toxicity to the tested environmental bioindicators and lower dispersion capacity than the biobased surfactants. All the green surfactants showed great emulsification capacity, especially against motor oil and petroleum. Therefore, their potential to remove motor oil adsorbed on different types of soils (sandy, silty, and clay soil and beach sand) was investigated either in kinetic (flasks) or static (packed columns) experiments. The commercial biosurfactant formulation showed excellent effectiveness in removing motor oil, especially from contaminated sandy soil (80.0 +/- 0.46%) and beach sand (65.0 +/- 0.14%) under static conditions, while, in the kinetic experiments, the commercial biosurfactant and the biobased 2 surfactant were able to remove motor oil from all the contaminated soils tested more effectively than the biobased 1 surfactant. Finally, the S. bombicola commercial biosurfactant was evaluated as a soil bioremediation agent. In degradation experiments carried out on motor oilcontaminated soils enriched with sugarcane molasses, oil degradation yield in the sandy soil reached almost 90% after 60 days in the presence of the commercial biosurfactant, while it did not exceed 20% in the presence of only S. bombicola cells. These results promise to contribute to the development of green technologies for the treatment of hydrophobic pollutants with economic gains for the oil industries.openda Silva, Israel Gonçalves Sales; de Almeida, Fabíola Carolina Gomes; da Rocha e Silva, Nathália Maria Padilha; de Oliveira, Joaquim Teodoro Romão; Converti, Attilio; Sarubbo, Leonie Asforada Silva, Israel Gonçalves Sales; de Almeida, Fabíola Carolina Gomes; da Rocha e Silva, Nathália Maria Padilha; de Oliveira, Joaquim Teodoro Romão; Converti, Attilio; Sarubbo, Leonie Asfor

Hydraulic conductivity and soil-sewage sludge interactions

One of the main problems faced by humanity is pollution caused by residues resulting from the production and use of goods, e.g, sewage sludge. Among the various alternatives for its disposal, the agricultural use seems promising. The purpose of this study was to evaluate the hydraulic conductivity and interaction of soil with sandy-silty texture, classified as Spodosols, from the Experimental Station Itapirema - IPA, in Goiana, state of Pernambuco, in mixtures with sewage sludge from the Mangueira Sewage Treatment Station, in the city of Recife, Pernambuco at rates of 25, 50 and 75 Mg ha-1. Tests were conducted to let water percolate the natural saturated soil and soil-sludge mixtures to characterize their physical, chemical, and microstructural properties as well as hydraulic conductivity. Statistical data analysis showed that the presence of sewage sludge in soils leads to an increase of the < 0.005 mm fraction, reduction in real specific weight and variation in optimum moisture content from 11.60 to 12.90 % and apparent specific dry weight from 17.10 and 17.50 kN m-3. In the sludge-soil mixture, the quartz grains were covered by sludge and filling of the empty soil macropores between grains. There were changes in the chemical characteristics of soil and effluent due to sewage sludge addition and a small decrease in hydraulic conductivity. The results indicate the possibility that soil acidity influenced the concentrations of the elements found in the leachate, showing higher levels at higher sludge doses. It can be concluded that the leaching degree of potentially toxic elements from the sewage sludge treatments does not harm the environment