Enhanced ozonation degradation of petroleum refinery wastewater in the presence of oxide nanocatalysts.

The catalytic activity of Mn2O3, FeOOH and CeO2 nanoparticles was evaluated in the treatment of a synthetic petroleum refinery wastewater (SPRW) using O3 in a discontinuous reactor at 25°C and pH 5.5. The mineralization and partial chemical oxidation rates of SPRW using these metal oxides are in the same order of magnitude, and the catalytic activity in the mineralization of SPRW decreased in the order Mn2O3 > CeO2 > FeOOH. The mineralized fraction progressively increased with time in the catalytic process while in the non-catalytic process it remained constant. The effect of the operational conditions on the mineralization and partial chemical oxidation rates using Mn2O3 was investigated in detail. The mineralization rate was found to be lower than the partial oxidation rate due to the formation of partially oxidized by-products, and this is dependent on the solids dosage and pH. An investigation of the mechanism demonstrated that the enhancement effect could be attributed to the introduction of the manganese oxide nanoparticles, which could promote the utilization of O3 and/or enhance the formation of free radicals (•OH, •O2H and •O2-) on the solid surface and further accelerate the degradation of the organic compounds present in the wastewater.

[A seroepidemiological survey on the island of São Luis during a dengue epidemic in Maranhão]. / Inquérito soro-epidemiológico na ilha de São Luis durante epidemia de dengue no Maranhão.

The island of São Luis in the State of Maranhão, constituted by the municipalities of São Luis-SL (835,428 inhabitants), São José de Ribamar-SJR (60,633 inhabitants) and Paço do Lumiar-PL (80,274 inhabitants), has been suffering dengue (DEN) fever epidemics since 1995, caused by DEN-1. In 1996, from August through October, an aleatory sero-epidemiologic survey was carried out in order to estimate the incidence of DEN infection and to analyze other clinical and epidemiological parameters. A questionnaire was applied and serum samples were simultaneously obtained. Serum samples were tested by hemagglutination inhibition (HI). Results were analyzed using Lotus 123, Epi-info 6.0, Excel 5.0 and STATA softwares. A total of 1,217 serum samples were obtained (101 of PL, 100 of SJR and 1017 of SL). The rate of DEN was 55.4% in PL, 28% in SJR and 41.4% in SL, suggesting the occurrence of 401,933 infections. No difference was seen between males and females, but infection occurred more in the upper social class than in poor people (p < 0.003), and was more frequent in adults than in children (p < 0.0004). In SL, the incidence was stratified into seven sanitary districts (SD), and prevalence was found to range from 26.1% in SD4 to 56.8% in SD1 (p < 0.0001). Symptoms were more frequently reported by people whose HI was positive: they included fever, headache, chills, dizziness, retrobulbar pains, muscle and joint pains, nausea, anorexia and skin rash. In spite of the high incidence of infection, no hemorrhagic cases were reported.