Evapotranspiration tank in the treatment of sanitary sewage at rural property

Abstract

The Evapotranspiration Tank consists of a waterproofed tank, filled with different layers of substrate and plants. Due to the scarcity of studies on the development and microbiological safety of vegetable species in TEvap, the objective was to evaluate the chemical and microbiological composition of vegetables produced in different positions of the TEvap system. The tank was implemented in the rural area of Triângulo Mineiro/MG, with the capacity to serve four residents. Approximately R$ 1,150.00 was spent on materials purchased in the region, a value lower than that estimated for the conventional septic tank and biodigester septic tank systems. As a result, it was found that the chemical composition of lettuce and arugula did not differentiate between the crops in the different positions of TEvap and the control. All coliforms found in the samples were thermotolerant, resulting in inadequate consumption. At the beginning of TEvap, the lettuce showed a higher concentration of coliforms, in contrast to the end of TEvap where the samples of lettuce and arugula showed a reduction of more than 50% of coliforms, however the irrigation water was pointed out as a possible vehicle of contamination of the vegetables. Thus, although the system is efficient in the treatment of black water, care should also be taken with the quality of irrigation water for the production of safe food.