RESUMEN
This study investigated for the first time the efficiency of an advanced oxidation process (AOP) zero valent iron/hydrogen peroxide (ZVI/H2O2) employing iron nails for the removal of Natural Organic Matter (NOM) from natural water of Regent's Park lake, London, UK. The low cost of nails and their easy separation from the water after the treatment make this AOP attractive for water utilities in low- and middle-income countries. The process was investigated as a pre-oxidation step for drinking water treatment. Results showed that UV254 removal in the natural water was lower than that of simulated water containing commercial humic acid (HA), indicating a matrix effect. Statistical analysis confirmed the maximum removal of dissolved organic carbon (DOC) in natural water depends on the initial pH (best at 4.5) and H2O2 dosage (best at 100% excess of stoichiometric dosage). DOC and UV254 removals under this operational condition were 51% and 89%, respectively. Molecular weight (MW) and specific UV absorbance (SUVA254) were significantly reduced to 74% and 78%, respectively. Formation of Chloroform THM in natural water sample after the ZVI/H2O2 process (initial pH 4.5) was below the limit for drinking water, and 48% less than the THM formation in the same water not subjected to pre-oxidation. Characterization of oxidation products on the iron-nail-ZVI surface after the ZVI/H2O2 treatment by SEM, XRD, and XPS identified the formation of magnetite and lepidocrocite. Results suggest that the investigated ZVI/H2O2 process is a promising technology for removing NOM and reducing THM formation during drinking water treatment.
Asunto(s)
Agua Potable , Contaminantes Químicos del Agua , Purificación del Agua , Agua Potable/análisis , Peróxido de Hidrógeno/química , Hierro/química , Uñas/química , Oxidación-Reducción , Contaminantes Químicos del Agua/química , Purificación del Agua/métodosRESUMEN
This discussion of smallpox prevention practices in the state of São Paulo focuses primarily on the Instituto Vacinogênico, created in 1892 as part of a sanitation reform that modernized public health in São Paulo state. Established and headed until 1913 by the renowned São Paulo surgeon Arnaldo Vieira de Carvalho, the institute was responsible for statewide distribution of the smallpox vaccine derived from animals. It operated on its own until 1918, when it was made part of the Instituto Bacteriológico.