Fenton Coagulation/Oxidation Using Fe2+ and Fe3+ Íons and Peracetic Acid for the Treatment of Wastewater

The Fenton coagulation/oxidation process is divided into two steps: coagulation, in alkaline pH and oxidation, in acid pH. This configuration provides a reduction in oxidant concentration, due to the pretreatment conducted in the coagulation step. This study proposes the substitution of hydrogen peroxide (HP) by peracetic acid (PAA) in a Fenton coagulation process to treat sanitary sewage and provide its disinfection. The new combination is proposed in a single step and presented good results in removing turbidity (98.5%), apparent color (95.4%), phosphorus (100%) and COD (58.2%) even at the effluent natural pH, besides demonstrating higher reduction in E. coli when compared with the process that employs hydrogen peroxide. The formation of Fe3+ ions was shown to be responsible for the removal of the particulate material. DOI: http://dx.doi.org/10.17807/orbital.v7i3.62

Home Composting Using Facultative Reactor

Concerns with the final destination of organic solid waste (OSW) generated in rural areas originate from the possibility of this waste harming the environment, in addition to producing bad smell and attracting pests, when improperly disposed of in the soil. In this sense, composting might be a suitable way of dealing with this residue. This chapter presents the advantage of treating rural OSW through composting in reactors. Facultative reactors present the advantage of not requiring handling or large areas for the waste processing, and they do not generate bad smell and do not attract pests, which represent common drawbacks of the conventional windrow composting process. The final product of this composting process can be used as fertilizer for crops, resulting in the economy, since commercial fertilizers do not have to be bought. Works carried out by the Analytical and Environmental Chemistry Research Group at the State University of Ponta Grossa—Brazil have reported important results regarding the use of facultative reactors with different OSW mixtures. From the monitoring of physical, chemical, biological and spectroscopic parameters, it was seen that composting in facultative reactors produced stable compost matured in a short period of time

Mechanical and hygroscopic characteristics of unidirectional jute/glass and jute/carbon hybrid laminates

Physical and mechanical performance of natural fiber composites can be tailored by hybridizing with synthetic fibers. Jute fibers are promising and highly available at a low cost in some countries, and they have been used in several applications, with the extra benefit of helping socially depressed people who commonly explore this plant. This work investigates the effect of hybridization on the properties of jute/glass and jute/carbon laminates with polyester resin. Nine different laminates were manufactured by vacuum infusion using unidirectional jute, E-glass, and carbon fabric reinforcements. Tensile, flexural, and short beam tests were performed in accordance with ASTM standards. The hybrid composites showed generally intermediate properties compared to the non-hybrid two-component laminates. The mechanical properties of the hybrid composites were 50–75% smaller than those of their respective pure glass and pure carbon composites, but 30– 300% higher compared to the pure jute composite. Among the hybrids, the number of layers of the synthetic fiber played the most important role on properties, rather than the layup. That is, the variation in the number of jute fabrics may produce the required combination of stiffness and strength for different applications. Besides, the hybrid laminates, with more layers of synthetic fibers showed better hygroscopic performance.天然纤维复合材料的物理和机械性能可以通过与合成纤维杂交来定制. 黄 麻纤维在一些国家很有前途, 而且价格低廉, 而且很容易获得, 它们已被用 于多种应用中, 有助于帮助那些经常探索这种植物的社会抑郁症患者. 本文 研究了杂化对聚酯树脂黄麻/玻璃和黄麻/碳层压板财产的影响. 使用单向 黄麻、E-玻璃和碳纤维增强材料通过真空浸渍制备了九种不同的层压板. 根据ASTM标准进行拉伸、弯曲和短梁试验. 与非混杂双组分层压板相比, 混杂复合材料通常表现出中等的财产. 混杂复合材料的力学财产比各自的 纯玻璃和纯碳复合材料小50-75%, 但比纯黄麻复合材料高30-300%. 在这些 杂种中, 合成纤维的层数对财产起着最重要的作用, 而不是铺层. 也就是说, 黄麻织物数量的变化可能会产生不同应用所需的硬度和强度组合. 此外, 具 有更多层合成纤维的混合层压板显示出更好的吸湿性能

Histopathological effects of silver nanoparticles in Rhamdia quelen after oral exposure

The studies about silver nanoparticles (AgNP) increased in the last years but few is known about their effects in Brazilian neotropical freshwater fish species. The current study investigated the effects of AgNP on adult silver catfish Rhamdia quelen after subchronic oral exposure. After nanoparticle (NP) size and area characterization fish were administrated with three different doses for 15 days (0.03, 0.3 and 3 μg g-1). The concentration of silver in liver and kidney was measured to evaluate the bioaccumulation and discuss its effects in the target organs. Liver bioaccumulated 15, 1.7 and 0.2 % of administered doses while kidney bioaccumulated 1.33, 0.33 and 0.9 % (respectively for 0.03, 0.3 and 3 μg g-1). The histopathological findings were considered in both organs to evaluate the effects of AgNP, according to Bernet’s Lesion Index (BLI). Also were included the melano-macrophages center (MMC) and new nephrons (NN) counting respectively in liver and posterior kidney. The results revealed morphological injuries as inflammation in both studied organs and vascular congestion and steatosis in liver, in a concentration dependent way. The presence of AgNP in the tissues revealed the bioavailability of the nanoparticle while the damages and morphological disturbs showed the potential risk of exposure in R. quelen, even under environmental relevant concentrations

Fenton Coagulation/Oxidation Using Fe2+ and Fe3+ Íons and Peracetic Acid for the Treatment of Wastewater

The Fenton coagulation/oxidation process is divided into two steps: coagulation, in alkaline pH and oxidation, in acid pH. This configuration provides a reduction in oxidant concentration, due to the pretreatment conducted in the coagulation step. This study proposes the substitution of hydrogen peroxide (HP) by peracetic acid (PAA) in a Fenton coagulation process to treat sanitary sewage and provide its disinfection. The new combination is proposed in a single step and presented good results in removing turbidity (98.5%), apparent color (95.4%), phosphorus (100%) and COD (58.2%) even at the effluent natural pH, besides demonstrating higher reduction in E. coli when compared with the process that employs hydrogen peroxide. The formation of Fe3+ ions was shown to be responsible for the removal of the particulate material. DOI: http://dx.doi.org/10.17807/orbital.v7i3.62

Determination of Smuggled Cigarette Characteristics in Brazil and Their Potential Risk to the Human Health

The objective of this study was to determine the different characteristics of tobacco found in thirty brands of smuggled cigarettes in Brazil. Determination of arsenic through atomic absorption spectrometry in graphite oven was carried out and classical methodologies were employed to determine dirtiness, total ash, insoluble ash, humidity, tobacco pH and sidestream smoke pH. The methodology used to quantify arsenic presented quantification limit of 15.0 ng g-1 and detection limit of 4.0 ng g-1 in dry tobacco mass. The recovery of arsenic for the method purpose was 98.2% and relative standard deviation 6.0%. About 56% of the brands were observed to have arsenic concentrations above 20.0 ng g-1, which means nearly twice as much as the arsenic found in cigarettes sold legally in Brazil. Levels above the recommended value for humidity were found in 53% of brands. About 96% of the brands presented total ash content above that indicated by the Brazilian Pharmacopoeia. About 53% of the samples contained levels of insoluble ash above the limit. In 90% of the samples, the smoke was alkaline. In dirtiness tests, 81.2% of the brands presented some kind of contaminant, such as fungi, insect fragments, grass or mites. The characteristics revealed that the consumption of this kind of cigarette can increase risks to consumer health. DOI: http://dx.doi.org/10.17807/orbital.v8i3.83

Effect of Bioaccumulation of Heavy Metals in Oreochromis niloticus Tissues of an Urban Lake in Southern Brazil

In this study, the effect of the bioaccumulation of metals on Oreochromis niloticus tissues was evaluated. Significant Co, Mn and Ni concentrations were found in the lake water near the fertilizer industries. In the sediment was identified the presence of Cd (4.612 ± 0.930 mg kg-1), Ni (46.847 ± 3.801 mg kg-1) and Zn (865.534± 89.437) mg kg-1) in concentrations above the probable effect level (PEL). For Cu (141.963 ± 5.148 mg kg-1) and Pb (53.362 ± 6.621 mg kg-1) concentrations between the threshold effect (TEL) or probable effect (PEL) levels. Regarding Oreochromis niloticus tissues, the concentration of metals in the liver was higher than found in muscle. The biomarkers indicated that the hepatic cells of Oreochromis niloticus are under oxidative stress, explained by the higher levels of reduced glutathione (GSH), lipid peroxidation (LPO) and protein carbonylation (PCO) when compared to control fish tissues. The set of biomarkers presented in this study contribute to define the effects of the bioaccumulation of metals in Oreochromis niloticus tissues. DOI: http://dx.doi.org/10.17807/orbital.v11i7.136

Compostagem de resíduos orgânicos domésticos em reator: um estudo sobre a formação de CH4 NH3 e a influência do isolamento térmico / Domestic organic waste reactor composting: a study on the formation of CH4 NH3 and the influence of thermal insulation

A compostagem em reator vem se mostrando uma alternativa promissora no tratamento de resíduos orgânicos domésticos. Neste trabalho avaliou-se a influência do isolamento térmico no funcionamento do reator e a liberação de NH3 e CH4 ao longo do processo. Para isso, construiu-se dois reatores, sendo que em um deles utilizou-se isolamento térmico. Para o monitoramento do processo de compostagem, realizou-se análises de temperatura e umidade. Para verificar a evolução das etapas de transformações da matéria orgânica durante o tempo analisou-se a evolução na liberação dos gases NH3 e CH4. Os resultados de temperatura, umidade, e emissão dos gases NH3 e CH4 mostraram distinção no processo de decomposição entre as partes superiores e inferiores dos reatores, com características aeróbicas (superior) e anaeróbicas (inferior), evidenciando um sistema facultativo. O reator com isolamento térmico apresentou menores diferenças de temperatura e maiores valores de umidade nos pontos analisados.

Post-treatment of Anaerobic Reactor Effluent by Double Filtration with Gravel and Clinoptilolite and Ozone Disinfection

Anaerobic reactors are an excellent alternative in the treatment of domestic effluents. However, this system presents the disadvantage of requiring post-treatment. Many technologies have been studied and rapid filtration systems have proven to be a viable alternative for the post-treatment of anaerobic reactor effluents. This study evaluates the efficacy of an anaerobic reactor effluent post-treatment system using double filtration (DF), which consists of an upward gravel filter and a downward filter of clinoptilolite, and disinfection by ozonation. The system was evaluated using physicochemical and microbiological parameters. The lowest ozone dose (0.4 mg L-1) indicated possible oxidation of fractions of biodegradable organic matter with BOD removals above 95%. Higher ozone concentrations (5.0 and 7.0 mg L-1) improved COD removal and total nitrogen removal. Regarding microbiological parameters, over 87% E. coli and 89% total coliforms could be removed only with the use of DF, while total inactivation was observed using doses above 5.0 mg L-1 ozone. The results showed that following the proposed treatment, the effluent treated with the DF/Ozonation combination meets the guidelines for reuse in toilets, irrigation of orchards, cereals, pastures, and other crops through runoff or by punctual irrigation system according to the NBR 13969/97. According to these results, DF using clinoptilolite followed by ozonation is a promising technology for the anaerobic reactor effluent post-treatment. DOI: http://dx.doi.org/10.17807/orbital.v13i4.161