Evaporation-transpiration tanks for rural sanitation: A case study in micro- and macro-planning

Abstract

Evaporation and transpiration tanks (TEvap) are a poorly explored option for the disposal and treatment of household sewage in rural areas. This is mainly due to the difficulty in including them in planning projects and in public policies aimed at rural sanitation. Current paper proposes a methodology for the integration of this technology in rural sanitation for the state of Minas Gerais, Brazil (macroscale), evaluating its application in the municipality of Itabira (microscale). Itabira was chosen for its rural population and local rainfall data, evaporation-transpiration, and choice of coefficients that characterized the infiltration of rainwater in the tank, sunshine and wind conditions. With regard to macroscale, evaporation-transpiration and rainfall maps overlap and identify 22 homogeneous regions. Taking into account the corresponding evaporation-transpiration, three different scenarios are evaluated: scenario with average precipitation and evaporation-transpiration rates (reference); high rainfall rate; low rainfall rate. TEvap were assessed by the data and seven regions were grouped with similar profiles for the TEvap. Macro procedure is useful to determine priority areas for TEvap and, consequently, in public policies for the rural area. However, for full implementation at the micro level, specific material should be developed to reduce the uncertainties for an increase in the area of TEvap (from 2.9 to 3.6 m2person-1), and to investigate the socioeconomic reality of each locality.