Aqualuz: assessing the drought in the brazilian northeast from the perspective of a new soodis technology

Abstract

This study addresses the drought problem in northeastern Brazil (NEB) by establishing the hypothesis that, during prolonged periods of water scarcity, diffuse rural communities are affected not only by reduced water availability in nearby dams, but also by the worsening in the quality of the water stored in them. For this, the Drought Index (SPI) and the Trophic State Index (TSI) of 155 reservoirs in the State of Ceará were comparatively evaluated, proving that, after drier years, such as 2013 (SPI=-2.43), there was an increase to 68% of the total number of reservoirs in eutrophic and hypertrophic states. Understanding this problem, it is introduced the Aqualuz, a new SODIS technology, presented as an alternative measure aimed at helping families with better management of water stored in cisterns in the face of prolonged periods of water stress. We carried out field, laboratory and modeling studies to evaluate its efficiency for the removal of Escherichia coli (EC) from cistern water, showing that Aqualuz needs exposure times (2.5-4.0h) and solar radiation. (250-410W/m²) lower for EC elimination than other SODIS technologies. A new relationship between solar radiation and water temperature was also obtained, which allowed simulations of EC decay models for 34 NEB municipalities with the device. In addition, its acceptability was evaluated within 52 families, in order to define the feasibility of the technology as an aid measure in terms of access to drinking water, having found a strong rate of use (92%).