Sistema de saneameno doméstico: eficácia do uso de fossa verde para o tratamento unifamiliar de esgoto

Abstract

The last demographic census indicated that the rural population of Tomé-açu, a medium-sized city in the interior of the Pará State, with production of black pepper and açaí among other Amazonian fruits, practiced inappropriate disposal of its sanitary sewage, using cesspits or discharging it directly into nature. In order to characterize the sanitation conditions in a rural community of Tomé-açu, the project initiated with the application of questionnaires in 61 residences. The results indicated the absence of public solid waste collection, of water distribution and treatment systems as well as no domestic sewage collection and treatment, increasing health risks factors among other social repercussions. Based on the above, the present work aimed to verify whether the materials available in the region could be reused for the construction of a green cesspool in order to treat black waters and to verify its effectiveness through microbiological analysis of the fruits grown on the cesspool. Two pits, with different dimensions, were installed in homes of two and four residents. Construction wastes, used tires, coconut shell and açaí shell were used; banana trees were planted on the surface. During the two-years follow-up, the families did not notice bad odors or recorded effluent leakage. Both pits proved to be efficient since the microbiological analyzes carried out in the first and second year of the project indicated concentrations of thermotolerant coliforms at 45ºC below 3 NMP.g-1 and absence of bacteria of the genus Salmonella, in the harvested fruits.