Design decisions, implying action despite uncertainty, may face exponential risks in dam engineering and must therefore be sorted out into two categories: those controlled by the statistics of extreme-value conditions, and those amenable to treatment under statistics and probabilities of averages. Absolute priority belongs to the first group, and it is emphasized that any computations connected with them are delusions. The designer must run away from the problem by 'choice of change ofstatistical universe'. Important examples are full interceptor filter-drainage inclined into upstream zone, stereometric hindrance seepage filtering, and use of a grout buffer to homogenize a zone of foundations exhibiting extreme dispersions of pervious discontinuities. Within statistics of averages an optimized embankment design is proposed based on flow nets; the advantages of an internal impervious blanket are shown. The behaviour of compacted embankment materials is accepted (as demonstrated in a companion paper) as evidencing prestressing; routine stability analyses are reappraised to permit significant economies and improved probabilistic factors of safety F; instrumentation is associated with Bayes' theorem to quantify the observational method. Finally, it is postulated that embankment dam engineering must begin to develop Satisfaction Indices with respect to average behaviour, in substitution for intangible F values with respect to catastrophe. Les decisions concernant un projet impliquent une action en depit dune incertitude. En matiere de barrages, elles peuvent comporter des risques exponentiels et de ce fait, doivent Ctre classees en deux categories: celles qui se referent a des statistiques relatives a des conditions extremes, et celles justiciables d'un traitement par statistiques et probabilites relatives a des moyennes.Une priorite absolue doit &tre donnee a la premiere categoric mais il est souligne que tout calcul dans ce domaine est depourvu de signification realiste: le concepteur doit lui tourner le dos en cherchant a resoudre le probleme par un choix d'univers physique tel que le phenombne soit exclus.
RESUMOO processo na indústria têxtil, principalmente nas etapas de tingimento e acabamento, requer um grande volume de água. A eliminação desses produtos tóxicos é atualmente um dos mais importantes assuntos em controle de poluição, o que tem levado os pesquisadores a buscar novas técnicas e ferramentas mais poderosas para diminuir ou eliminar a toxicidade dos efluentes líquidos formado em seus distintos processos, sempre levando em conta a eficiência, baixo custo e as regulamentações e legislações voltadas à proteção ambiental. Neste trabalho foi avaliada a aplicação de um resíduo argiloso em processos de tratamento de efluentes de indústrias têxteis para remoção de corantes. Foi realizado um estudo de caracterização do adsorvente através da análise da área superficial e do volume poroso (BET), assim como também a análise de presença de minerais do grupo da esmectita (difração de raios-X). Também foi realizada a otimização do processo adsortivo através da técnica de planejamento fatorial para os corantes Nylosan Azul Brilhante e Azul Anil Op. A análise de BET mostrou que o tratamento térmico provocou uma redução na área superficial de 13,3%, todavia provocou um aumento no tamanho dos poros de 21,2%. A análise dos difratogramas de raios X das amostras in natura indicou a presença dos grupos minerais esmectita, caulinita e mica (ilita). Foi observada, ainda, a participação do mineral quartzo (d001 = 3,35 Å) no conjunto dos minerais presentes na argila. Com o auxílio do planejamento fatorial para os dois corantes, verificou-se a influência significativa no processo da variável massa, velocidade de agitação e temperatura. Obtiveram-se resultados satisfatórios na redução da concentração por adsorção, mostrando-se que a amostra em estudo é eficaz para a remoção dos corantes ácido Nylosan Blue e reativo Azul anil Op. Palavras-chave: adsorção, corantes, argilas. ABSTRACTThe textile industry process, especially in dyeing and finishing steps, requires a large volume of water. The elimination of these toxic products is currently one of the most important subjects in pollution control, which has led researchers to seek new techniques and more powerful tools to reduce or eliminate the toxicity of wastewater formed in its different processes, always taking into account efficiency, low costs and the laws and regulations aimed at environmental protection. In this study we evaluated the application of a clay waste in processes of wastewater treatment for removal of textile dyes. A study was conducted to characterize the adsorbent through the analysis of surface area and pore volume (BET), as well as the analysis of the presence of smectite group minerals (X-ray diffraction). The optimization of the adsorptive process through the technique of factorial design was used. The BET analysis showed that the heat treatment caused a reduction in the surface area of 13.3%. However caused an increase of 21.16% in the pore size. The analysis of X-ray diffractograms of the samples indicated in nature, therefore, the presence of mineral grou...
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