137 resultados para CATIONIC RESIDUES


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The stagnant effective thermal conductivities (K0) of sugar cane bagasse (SCB), wheat bran (WB), orange pulp and peel (OPP) and their combination (weight proportion 1:2:2 SCB/OPP/WB) were obtained using the line heat source method. These solid materials were applied to pectinase production via solid-state fermentation. The moisture content ranged from 4 to 80% (w.b.). A conduction mechanism through the porous media was observed, along with conduction through a liquid film and contact thermal resistance between the samples and the probe. K0 was low for intermediate moisture contents and approached the molecular conductivity of water for high moisture contents. © 2013 Copyright Taylor and Francis Group, LLC.

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This paper presents a research on the environmental impacts of particleboards produced from wastes, based on a comparative Life Cycle Assessment study. The particleboards were manufactured in laboratorial scale from the following residues: sugarcane bagasse (Saccharum spp.) and pine wood shavings (Pinus elliottii). The study was developed following the methodological guidelines of ISO 14040. The functional unit adopted was the m2 of the particleboards produced and the impacts were evaluated by the Environmental Development of Industrial Products method. The results indicated that pine particleboard present the highest environmental impact potential. Our findings suggested that the factors that mostly aggravated the environmental impacts were: the distance between the raw materials and the production site, and formaldehyde emissions (FE). The first is related to the combustion of fossil fuel during the acquisition of raw material, which achieved the values of 2185.94 g/m2 for consumption of non-renewable resources for pine particleboard and 893.53 g/m2 for bagasse particleboard. The second is related to the use of urea-formaldehyde resin, responsible for the FE into the air during production. The FE is accountable for the contamination of approximately 7,800,000.00 m3 of air per m2 of particleboard produced, and was the factor with the greatest impact in human toxicity potential. © 2013 Elsevier Ltd. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Biofísica Molecular - IBILCE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

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The cutting of plant residue in no-tillage systems under certain environmental conditions becomes necessary to adequately establish and grow crops. This study aims to assess the effect on the yield of different methods of managing millet plant residue in cotton plantations. The study was conducted during the agricultural years 2006/07 and 2007/08, and the treatments included no-mechanical-treatment tillage and the use of a rotary shredder, crimper-roller, and mechanical disintegrator for millet plants before sowing the cotton. Evaluations were performed for the residue fragmentation, emergence speed, percent of soil cover during the cycle and yield of the cotton crop. The emergence speed was faster in the management with the rotary shredder. In 2006/07, the no-tillage treatment showed a rate of loss for soil cover that was 46 percent greater than the disintegrator treatment. The rotary shredder and the disintegrator yielded greater soil coverage during the cultivation cycle, and the yield was highly correlated with the soil cover at 75 days after emergence. The management of the millet residue affected the cotton plants for the two-year study period.

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Understanding soil responses to the application of urban or industrial residues is necessary. In the current experiment, both sources of residues were applied to the soil surface of a Hapludox soil for 8 years. The four residues studied were biodigested and centrifuged sewage sludge (LB and LC, respectively), steel slag from the metallurgic industry (E), and limed mud from the pulp and cellulose industry (LCal). The residues were applied at 0, 2, 4, and 8 Mg ha(-1) four times from 2002 to 2010 when soybean was cultivated in the summer and lopsided oat and sorghum were cultivated during the winter. The contents of heavy metals were evaluated with diethylenetriaminepentaacetic acid (DTPA) and organic acids. The LB was the residue that increased the contents of soil micronutrients and heavy metals to their greatest levels, although within limits that impair the risks of environmental contamination.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)