Avaliação do potencial de reúso de água para irrigação e do risco de contaminação microbiológica em seres humanos

Abstract

The current paper presents a discussion the evaluation of the potential of water reuse for irrigation and the risk of microbiological contamination in human beings. For the development of the reuse potential, it can be concluded that planning is essential for the success of urban and rural infrastructure projects focused on sanitation and water resources, where the evaluation studies of water reuse potential are inserted. In the application of reuse potential, a survey of the flow of all WWTPs in Brazil and the demands for irrigation for the 12 Brazilian Hydrographic Regions was carried out. Thus, it was observed that the total flow of sewage generated in Brazil, from secondary effluent, represents 9% of the total water demand for irrigation in the country (1,078.71 m3/s) and that only 7% of the flow treated in Brazil is going through a disinfection stage. The Microbiological Risk Assessment (SqMRA) was divided into four stages: 1) Identification of Hazards; 2) Identification of exposure routes for different receptors; 3) Exposure Scenarization; 4) Risk characterization. Next, SqMRA was applied to 3 different cases, the first being virtual through localized irrigation, with a drip system, for edible culture, preferably raw, and without bark; the second applied the methodology for the type of coffee crop, drip irrigated and grain crop with center pivot irrigation; and the third was for rice farming in two scenarios, in which the first considers the effluent to be disinfected (Hazard 7), and the second considers the reality of sewage treatment conditions in Brazil (Hazard 9). Thus, it was observed that water reuse can be applied to different types of crops and irrigation methods, obtaining an acceptable global risk for the receptors involved (farmer, consumer and neighborhood). However, the relevance of disinfection to minimize the risk in any application of water reuse is highlighted, as it is also necessary to plan the advances in the rates of service with sewage treatment, considering the technical, economic and logistical possibility of irrigation service of the most appropriate crops, with water reuse.