Ivo André Homrich Schneider

Eichhornia crassipes as biosorbent for heavy metal ions

Abstract Eichhornia crassipes approaches being a scourge in many parts of the world, choking waterways and hindering transport upon them. At the same time it is known to readily abstract heavy metal ions from water and, thus, aids in the removal of heavy metals found in such waters. This paper considers the possibility of using dried parts of the plant as an inexpensive adsorbent for the removal of heavy metals from contaminated chemical and mining industry waste waters. In particular the root of the plant was found to be an excellent accumulator of divalent heavy metal ions from solution although the entire biomass of the plant was also found to be a good sorbent for these ions. It is also suggested that the dried biomass of the plant might be placed in simple bags and used in a very low cost metal ion removal system.

Avaliação da perda da coloração artificial de ágatas

O Rio Grande do Sul e um dos principais produtores de geodos de agatas do mundo. As agatas da regiao de Salto do Jacui permitem a introducao de alguns corantes em seus poros, tornando-as coloridas. O objetivo do presente trabalho foi estudar a perda de cor de agatas tingidas artificialmente, considerando diferentes ambientes de exposicao. Estudaram-se agatas coloridas pelos procedimentos classicos (verde, vermelho, azul e preto) e coloridas com corantes orgânicos (verde, vermelho, rosa e roxo). O procedimento experimental consistiu em expor as chapas de agatas em tres ambientes com luminosidades distintas: escuro, domestico e ao ar livre. A evolucao da cor foi avaliada pela tecnica de colorimetria diferencial, usando o sistema colorimetrico CIE L*a*b*. Os resultados obtidos demonstram que os metodos classicos de tingimento proporcionam cores permanentes, enquanto que os corantes orgânicos promovem cores instaveis. Dependendo do grau de luminosidade e tempo de exposicao, a perda de cor pode ser praticamente total.

Caracterização de um depósito de rejeitos para o gerenciamento integrado dos resíduos de mineração na região carbonífera de Santa Catarina, Brasil

Brazilian coals contain high levels of impurities (pyrite and sedimentary rocks minerals), requiring concentration procedures. The coal tailing deposits demand a large physical area, whose topography is changed and acid mine drainage (AMD) is generated. The aim of this work was to characterize a typical coal tailing deposit in the carboniferous region of Santa Catarina, seeking the separation of three fractions for future reuse: (a) a fraction for energy production; (b) a fraction composed mainly by silicate minerals; and (c) a fraction with a high concentration of pyrite. The work methodology consisted in sample collection and characterization of the material. The characterization included particle size analysis, dissymmetric studies, XRD analysis, petrography studies, and acid-base accounting tests. The results showed that 68% of the material is composed of coarse particles, 15% of fine particles, and 17% of slurry from settling ponds. It is possible, by gravimetric concentration of the material, to recover 33.7% for energetic application and 10.3% as a pyrite concentrate. The remaining material, with intermediate density, will have a decrease of about 60% in its net acid generation potential and presents potential for application in civil engineering construction.

Ensaios estáticos e cinéticos para a prevenção da geração de drenagem ácida de minas da mineração de carvão com escória de aciaria

Abstract The Acid Mine Drainage (AMD) is the result of thenatural oxidation of sulphide minerals when exposedto the combined action of water and oxygen. One of thetechnologies to prevent the AMD consists in the alkalineadditive method. Thus, the aim of this work was to study,at laboratory scale, the DAM control by blending coalwaste with a metallurgical slag. A coal-tailing samplewas collected from a coal mine and the slag wasobtained from a semi-integrated steel plant, both locatedin Rio Grande do Sul State, Brazil. Static tests werecarried out by the acid-base account method todetermine the balance between the acid producing andacid consuming (neutralizing) mineral components ofthe sample. Later, kinetic tests were conducted inhumidity cells, following the ASTM D 5744-96 method.The results showed that the coal tailing generates DAM.However, the environmental problems can be minimizedmixing the coal waste with the metallurgical slag in a4,8:1 proportion. The kinetic experiments proved that,in this condition, the lixiviate presents a higher pH andlower concentration of acidity, metals and sulphate.Finally, it is possible to conclude the blending slag incoal tailing deposits can be a viable alternative forDAM control in coal mining.

A compact remediation system for the treatment of groundwater contaminated with BTEX and TPH.

ABSTRACT Gas stations constitute important point sources of soil and groundwater pollution. The leaking of hydrocarbons into the soil is a significant environment issue due to the wide-ranging occurrence of leaks and the high levels and toxicity of pollutants involved in the contamination of groundwater for human use. This study introduces a compact system developed to treat groundwater contaminated with benzene, toluene, ethyl benzene, and xylenes (BTEX) and total petroleum hydrocarbon (TPH) leaked from gas station tanks. The system comprises three units: (1) suction and volatilization of volatile organic compounds (VOCs), (2) aeration tank (to remove volatile organic substances), and (3) an adsorption packed-bed filter (activated carbon (AC) and rice husk ash, 50% each, to remove TPH). Contaminated groundwater was characterized in a pilot study and in the field. Levels of BTEX and of TPH decreased by 96% with an 8-h retention time. The results obtained show that the remediation system is highly efficient and yielded water that met the discharge standards defined in the Brazilian legislation, that is, maximum benzene, toluene, and xylene levels of 5, 170, and 300 μg/L, respectively.

Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks

Abstract Resumo Commercial coal production in the southern region of Brazil has been occurring since the beginning of the twentieth century. Due to the geologi-cal characteristics of the region, large amounts of solid wastes are generated. The aim of this work was to evaluate the use of coal waste to produce concrete paving blocks. A procedure to process the coal waste with the purpose of reducing the sulfur content and changing the particle size distribution of the material to meet the specification of fine aggregates was developed. The methodology considered the following steps: (a) sampling of a coal mining waste; (b) gravity separation of the fraction with specific gravity between 2.4 and 2.8; (c) comminution of the material and particle size analysis; (d) technological characterization of the material and production of concrete paving blocks; and (e) acidity generation prediction (environmental feasibility). The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks in a proportion of up to 50%. This practice can result in cleaner coal production and reduce the demand for exploitation of sand deposits.

Coal waste processing to reduce costs related to acid mine drainage treatment - case study in the Carboniferous District of Santa Catarina State

Coal wastes contain many minerals, including the pyrite, which oxidize and generates the acid mine drainage (AMD), a highly polluting effluent. Currently, the Brazilian coal mining operations emphasise AMD control using waste water treatment systems which consume substantial amounts of reagents and generate large amounts of sludge. The aim of this work was to study the acid mine drainage control by another approach, the sulphide exclusion preventive method. The method comprises in removing the pyrite form coal tailings, reducing the acid generation and minimizing the metals load in wastewater treatment plants. Accordingly, a typical coal waste sample was submitted to a density separation process to divide the sample in the following relative density ranges: below 2.2, from 2.2 to 2.7 and above 2.7. All density fractions were submitted to ultimate and proximate analysis. Static and kinetic tests were carried with the raw waste and the pyrite-free fraction. The results showed that, by gravity processing of coal tailings, it is possible to decrease 30% the volume of wastes. The remaining material presents an acid generation potential of about 80-90% lower than the raw waste. Furthermore, it is expected a reduction in costs of reagents of approximately 85% in acid mine treatment plants.