RESUMO
Efficient monitoring and control schemes are mandatory in the current operation of biological wastewater treatment plants because they must accomplish more demanding environmental policies. This fact is of particular interest in anaerobic digestion processes where the availability of accurate, inexpensive, and suitable sensors for the on-line monitoring of key process variables remains an open problem nowadays. In particular, this problem is more challenging when dealing with batch processes where the monitoring strategy has to be performed in finite time, which limits the application of current advanced monitoring schemes as those based in the proposal of nonlinear observers (i.e., software sensors). In this article, a fractal time series analysis of pH fluctuations in an anaerobic sequential batch reactor (AnSBR) used for the treatment of tequila vinasses is presented. Results indicated that conventional on-line pH measurements can be correlated with off-line determined key process variables, such as COD, VFA and biogas production via some fractality indexes.
Assuntos
Reatores Biológicos/microbiologia , Resíduos Industriais , Águas Residuárias/microbiologia , Anaerobiose , Concentração de Íons de Hidrogênio , Fatores de TempoRESUMO
OBJECTIVE: To evaluate malnutrition prevalence in children under five years-old in Tabasco, Mexico, during 1996, and their evolution in 1991-1996. MATERIAL AND METHODS: A cross-sectional study, including 1,256 children under five years-old in 593 communities (31 urban and 562 rural) from 17 sanitary districts. RESULTS: The weight/age indicator for malnutrition in children under five years old showed 59% of children had normal nutrition and 41% with malnutrition, distributed as follows: 26.12% slight, 12.62% moderate and 2.39% severe. In children between 1-5 years old, malnutrition prevalence was 45%. CONCLUSIONS: The number of children with malnutrition in Tabasco during the study period (1991-1996) has decreased in proportion to the increase of those with normal nutrition. Based on the health system activities, the number of health districts with critical malnutrition indicators decreased from 6 to 4.
Assuntos
Distúrbios Nutricionais/epidemiologia , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , México/epidemiologia , Prevalência , Saúde da População Rural/estatística & dados numéricos , Saúde da População Urbana/estatística & dados numéricosRESUMO
Childhood malnutrition is an important and prevailing public health problem in Tabasco, Mexico, where precise information is still lacking. Tabasco Public Health Department has been working on this problem since 1991. The first nutritional survey was carried out to recognize the nutritional level of 935 randomly selected children between 1-4 years of age in 17 municipalities of the state. A proportion of 46% of childhood malnutrition level was found in this Mexican state (29.8 low, 12.8% moderate and 3.4% severe). Ninety percent of severe childhood malnutrition cases were located in the rural municipalities of Tacotalpa, Nacajuca, Jonuta, Macuspana and Centla. These municipalities were more affected, with a malnutrition prevalence of 63%, 62.2%, 60%, 59.5% and 59.4%, respectively. Results from these surveys identify high risk areas and may serve to advance specific proposals for nutrition interventions.