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991.
Stephanie Lansing Jay F. Martin Raúl Botero Botero Tatiana Nogueira da Silva Ederson Dias da Silva 《Biomass & bioenergy》2010,34(12):1711-1720
A nine-month co-digestion investigation was conducted in Costa Rica to optimize animal wastewater treatment, renewable energy production, and fertilizer creation using 12 Taiwanese-model, plug-flow digesters (250 L each) constructed of tubular polyethylene and PVC piping, operating without mechanical or heating components. The experiment tested three replications of four treatment groups: the control (T0), which contained only swine manure, and T2.5, T5, and T10, which contained 2.5%, 5%, and 10% used cooking grease (by volume) combined with swine manure.T2.5 had the greatest methane production (45 L d?1), a 124% increase from the control. No adverse effects were observed from co-digesting 2.5% grease in terms of organic matter removal, pathogen reduction, grease removal, and pH. Chemical oxygen demand (COD) was reduced 94.7% to 1.96 g L?1, fecal coliforms and Escherichia coli were reduced 99.2 and 97.1%, respectively, and grease removal was 99.9%. The average effluent pH (7.05) and alkalinity in T2.5 was within the optimal range for methanogens and increased significantly during the nine-month experiment, likely due to adaptation of the methanogenic organisms to the influent grease concentrations. Total nitrogen concentration decreased 34.0%, and NH4-N increased 97.1% during digestion in T2.5, with no significant differences between T2.5 and T0. There was less phosphorus reduction with co-digestion, with 181 mg g?1 of total phosphorus (TP) in T2.5 and only 90.6 mg g?1 of TP in T0, resulting in lower N:P ratios in the grease treatment groups due to the greater concentration of phosphorus in the effluent. 相似文献
992.
Emiliane Andrade Araújo Nélio José de Andrade Luis Henrique Mendes da Silva Antônio Fernandes de Carvalho Cleuber Antônio de Sá Silva Afonso Mota Ramos 《Food and Bioprocess Technology》2010,3(3):321-332
Bacteria and other microorganisms have a natural tendency to adhere to surfaces as a survival mechanism. This can occur in
many environments, including the living host, industrial systems, and natural waters. The general outcome of bacterial colonization
of a surface is biofilm formation, which consists of microorganisms immobilized in a variety of polymeric compounds generally
referred to as extracellular polymeric substances. Bacterial adhesion to a solid surface is a crucial step in the biofilm
process. This step is dependent upon van der Waals, electrostatic, and acid–base interactions. These interactions are influenced
by physicochemical properties of the substratum and the bacterial surface, such as hydrophobicity, surface charge, and electron
donor–electron acceptor properties. In addition, the roughness of the substratum and the microbiological characteristics of
the cell surface, such as cellular appendages and production of exopolysaccharides, can affect the adherence process. To date,
many strategies have been developed to decrease the adherence of bacteria to surfaces. Surface modification with the addition
of the suitable compounds makes surfaces less attractive for microorganisms and therefore prevents bacterial adherence and
biofilm formation. 相似文献
993.
Maurício Pinheiro de Oliveira Caroline Reggiani Silva Lilia Müller Guerrini 《Journal of Coatings Technology and Research》2011,8(4):439-447
This study investigates the influence of carboxylic monomers, such as itaconic acid (IA), on the colloidal properties of the
latexes made by semi-continuous emulsion copolymerization of styrene (STy) with n-butyl acrylate (BA). A number of copolymerization runs were carried out with different IA concentrations. The effect of functional
monomer on the overall conversion, the colloidal properties of the latexes, and the distribution of the carboxylic groups
(buried, particle surface and aqueous phase) were examined. The carboxylic groups present in the latexes were analyzed using
conductimetric and potentiometric titrations. The behavior of the IA on the wet scrub resistance of highly pigmented paints
for architectural coatings was examined and correlated with the distribution of the carboxylic groups. The results obtained
showed that the properties of highly pigmented paints are greatly dependent on the amount and distribution of the carboxylic
groups. The carboxylic acid distributed in the aqueous phase has a strong influence on the wet scrub resistance and on the
characteristics of the final products. 相似文献
994.
Marcelle Nardelli Baptista Ricardo Valcarcel Vandré Maya Fernando Canto 《Water Resources Management》2014,28(13):4781-4793
The primary goal of this study is to identify floodplains that are in large river basins and could potentially undergo renaturalization of their hydrologic functions. The study area is the Paraíba do Sul River Basin (55,400 km2), which is located in southeastern Brazil. The field work included the application of geoprocessing techniques (ArcGIS 10 and ENVI 4.7) for the delineation and individualization of the floodplain, and the following characteristics were surveyed: area, perimeter, circularity index and urbanization index. Discriminant and cluster analyses (SPSS 15) were performed, and 77 floodplains were found that exhibited a wide variation in area (0.13 to 1,540 km2) and perimeter (1.8 to 4,200 km), low circularity indices (<0.52), and a low average urbanization index (18.9 %). The floodplains were grouped according to how well the renaturalization of their hydrologic functions could be managed and categorized as follows: a) low management potential (9 units); b) medium management potential (15 units); and c) high management potential (52 units). The discriminant analysis correctly classified 100 % of the cases, which indicates that the model has a high predictive ability and can accurately classify the management potential of floodplains. 相似文献
995.
J. R. Ochoa F. J. Escudero Sanz P. M. Sasia A. Santos García E. Díaz de Apodaca P. Río 《应用聚合物科学杂志》2007,103(1):186-197
Acrylamide/2‐acryloxyethyltrimethylammonium chloride copolymers in inverse microemulsions, with 60% 2‐acryloxyethyltrimethyl ammonium chloride in the monomer feed and a concentration of active matter of 30% (w/w) as flocculants, were obtained by inverse microemulsion copolymerization. Inverse microemulsion formulations of comonomers, interesting from both technical and economical viewpoints, were polymerized by semicontinuous free‐radical copolymerization with sodium disulfite as the initiator. The influence of the formulation composition, hydrophilic‐lipophilic balance (HLB), starting polymerization temperature, and reaction time on the polymerization and final properties of the products as flocculants was studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:186–197, 2007 相似文献
996.
Ian W Hamley Valeria Castelletto Nágila MPS Ricardo Maria EN Pinho Colin Booth David Attwood Zhuo Yang 《Polymer International》2007,56(1):88-92
Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E137S18E137, E82S9E82, E76S5E76, E62P39E62, and of two mixtures: E137S18E137 and E62P39E62 (Mix 1) and E82S9E82 and E62P39E62 (Mix 2), each 50/50 wt%. E = oxyethylene, CH2CH2O; S = oxyphenylethylene, OCH2CH(C6H5); and P = oxypropylene, OCH2CH(CH3). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E137S18E137, E82S9E82 and E62P39E62 packed into body‐centred cubic (BCC) structures. Gels of E76S5E76 were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry 相似文献
997.
In an attempt at improving bioethanol production, a bench‐scale comparison has been performed between the traditional one‐step process of sugarcane bagasse hydrolysis with 70 % sulfuric acid, and a modified operation including a second step with more dilute acid, at higher temperature. The influence of the reaction time, the percentage of solids in the sugarcane bagasse suspension and temperature on the hydrolysis efficiency, was investigated. Although the modified protocol allows for an appreciable improvement in the yield of conversion to fermentable sugars in comparison to the one‐step hydrolysis, a technical/economical analysis demonstrated that it would demand higher production costs and a longer payback period. Therefore, the latter process should be recommended for the setting up of a pilot plant with a production capacity of 80 m3 of alcohol per day. 相似文献
998.
Identification, localization and quantification of structural damage can be performed through a model-updating procedure. Model-updating methods require a baseline finite element (FE) model of the undamaged structure, which imposes a restriction on their applicability and can become very problematic especially for large and complex civil structures. Modeling errors in the baseline model whose effects exceed the modal sensitivity to damage are critical and make an accurate estimation of damage impossible. This paper presents an identification algorithm using modal data for assessing structural damage that is based on FE-updating procedures and takes modeling error into account. To overcome its influence, differences of mode shapes and frequencies before and after damage for both numerical model and experimental measurements are used instead of the mode shapes and frequencies themselves. To formulate the objective function, two different approaches have been considered taking into account how these differences are grouped: a single-objective approach and a multiobjective approach. The effectiveness of both approaches is verified against numerical and experimental results. 相似文献
999.
1000.