Avaliação da eficiência da radiação gama na desinfecção de esgoto doméstico bruto e esgoto tratado em reator UASB

Abstract

The rise of deterioration, observed on a quality of water, has been worrying the researchers, chiefly about the disposal and reuse of domestic wastewaters. The discharge of sewage in the environment must not: alter the principal use of fountains of water, damage the ecosystems, or put in risk the human health. One of the mainly problems from the reuse of wastewaters is the presence of patogenic organisms. The reuse of sewage, for noble purposes, requires an efficient process of desinfeccion. The coliforms termotolerantes and the eggs of Ascaris lumbricoides are considered good indicators of desinfeccion studies. For instance, a safe reuse of effluent, used to irrigate, must demand concentration of: coliforms termotolerantes NMP 1000/100 mL and eggs of helmintes 1 egg/L. The researches should get alternative techniques more efficients than the currently methods for desinfeccion of effluents, with the main objective in reducing the quantity of patogenics in sewage and, consequently, in the environment. The ionizing irradiation gamma has been tested and the results has been shown that this kind of irradiation is an efficient process for desinfeccion and degradation of pollutants found in domestic wastewater. In this job, the gamma irradiation was used in: concentration of coliforms termotolerantes, number of species of entherobacters, concentration of heterotrophics bacterias and the eggs of A. lumbricoides, found in the raw effluent and effluent from UASB reactor (UFMG/COPASA). Besides, it was evaluated the residual action produced by irradiation process. The sewage was irradiated in Laborátorio de Irradiação Gama (LIG) in Centro de Desenvolvimento de Tecnologia Nuclear (CDTN), in Belo Horizonte-MG. The source of irradiation was 60Co, with current activity of 37.000 Ci (2005). The results shown that a portion of irradiation (2,5 kGy) removed 98% of eggs of A. lumbricoides, 99,99% of coliforms totais, 99,98% of coliforms termotolerantes and 99,59% of heterotrophics bacterias in raw sewage. In the treated sewage, it was found a reduction in: 98% of eggs of A. lumbricoides, 99,9999% of coliforms totais, 99,9999% of coliforms termotolerantes, and 99,92% of heterotrophic bacteria. To avoid the recolonization of irradiated samples, portion of irradiation above 3 kGy should be used