Desenvolvimento de metodologias de cálculo para o projeto de hidrociclones no adensamento do lodo gerado nas estações de tratamento de água

Abstract

As the years go by, the drinking water consumption in the world has increased due to population, industrial and economic growth and other natural factors that affect some regions. When it comes to water consumption, it is critical to change the population's awareness, adopting other routine habits, such as, at bath time, avoiding leaving the shower longer than necessary; when washing the dishes, not leaving the tap running the entire time; and stop using garden hoses to wash sidewalks and cars. The reutilization of water has been studied and tested for some years now, and is currently gaining popularity due to the critical moment in which we live, where people around the world have been affected by dryness and droughts. In the regard of a better use of water, aiming its sustainability, stand the Water Treatment Stations (WTSs), which must adapt to this need. When it comes to the processes involved in the WTSs, it is known that nowadays the vast majority of them generates large amounts of water in the filters washing, which are dismissed without proper reutilization. In conventional WTS blueprints, there is a loss of the total volume of water captured by rivers, dams, lakes and wells, due to the step of retrowashing the filters. This retrowash water ends up becoming waste, since the WTSs do not have an engine to recover them. The destinations for the retrowash water are the direct disposal of it or the return to the raw water supply line in the conventional blueprint. However, this generates a pH and residual chlorine alteration, and increases the readings of iron, aluminum and m’anganese present in the water, which can cause health risks. Given the above, this paperwork aimed to develop a calculation methodology for the hydrocyclone project in the densification of the sludge generated in the WTSs. The hydrocyclone is designed for solid liquid separation, making it possible to adapt it to recover the volume of water that was dismissed before. Through research in articles, data about the physical and granulometric characterization of the sludge from WTSs were collected. Based on these, it was made possible to design hydrocyclones using the equations proposed by Massarani (2002) for Rietema and Bradley hydrocyclones. A parametric sensitivity analysis was performed to verify the hydrocyclones separation efficiency. Through the analyzes, the physical properties of the sludge and some process variables were altered to confirm the separation efficiency of the methodology used. The obtained results confirm the viability of using Rietema and Bradley hydrocyclones as an alternative to densify the sludge from WTSs.