EVAPOTRANSPIRATION TANK - TEVAP
The TEVAP system, or Evapotranspiration Tank, is an innovative individual solution for the treatment and final disposal of effluents from domestic toilets. This system allows the proper disposal of human waste without causing water, soil or air pollution. Based on technical knowledge and practical experience, TEVAP uses easily obtainable materials, such as used tires, construction debris, bamboo and other locally available resources, and is designed to promote sustainable development, being environmentally correct, economically viable and socially fair.
PROBLEM SOLVED
The lack of basic sanitation infrastructure was identified by the Traditional Communities Forum (FCT) as one of the main vulnerabilities that need to be strategically addressed to promote health, quality of life and contribute to the permanence of traditional communities in their territories. Practically all of these communities face significant deficiencies in terms of the Water Treatment System, making it extremely important to adopt sustainable solutions.
SOLUTION ADOPTED
The TEVAP (Evapotranspiration Tank) system was adopted because it is an efficient and sustainable solution for treating and reusing nutrients from toilet effluents. This closed system promotes the anaerobic decomposition of organic matter, followed by mineralization and absorption of nutrients by plants. All TEVAP implementation projects are developed and agreed upon in dialogue with various local stakeholders, including communities, the City Hall, the Ilha Grande Watershed Committee (CBHBIG) and environmental institutions in the region. To implement TEVAP technology, a surface area of 2m² per person is adopted if the system is used to treat all sewage produced, including gray water. The recommended construction dimensions are: 1.5m deep, 2m wide and a length equal to the number of taxpayers served by the system. If the system is used only for toilet water, depending on the rainfall conditions of the area, the area may vary from 0.5 to 1 m² per person. In situations with many taxpayers, the system can be divided into more than one tank operating in parallel to facilitate construction. The TEVAP system is functionally simple and does not require maintenance, with an indefinite useful life. If built according to the recommended specifications, the liquid material will be evapotranspired and the solid material will be absorbed by the plants. The structure consists of a waterproof rectangular tank, sized for a family unit, filled with a tunnel of used tires and different layers of substrate (rubble, gravel, sand and soil). The tank is planted with fast-growing plant species, superficial roots, large leaf area and high water demand. This technique has potential for application in the treatment of domestic wastewater, and can be used to treat all the sewage produced or only for toilet water, which reduces the cost of material and the area required. At the Martin de Sá School, located in the Caiçara Community of Praia do Sono, all wastewater was directed to the TEVAP system, with the addition of a grease trap for grey water. This example demonstrates the versatility and effectiveness of the system in different contexts and scales.
RESULT ACHIEVED
By September 2024, a total of 12 evapotranspiration tanks (TEVAP) were built with the support of Fiocruz and FCT in Praia do Sono in agreement with community leaders. During the construction process of the TEVAPs, the Ecological Sanitation Manual was launched and the Course Health in Traditional Territories: Social Technologies in Ecological Sanitation was held, in partnership with the National School of Public Health (ENSP) with the participation of SUS workers.