Model improvement for estimating of water turbidity removal efficiency in helical tubular flocculators

Abstract

Scientific studies have been demonstrating that helical tubular flocculators (HTFs) have high efficiency in floc formation and low hydraulic retention time when compared to flocculators commonly used in water and wastewater treatment. However, its practical application is still limited because there is still a significant demand for advances in the understanding of the relationship between the hydrodynamics of the unit and the flocculation process, as well as for criteria and methodologies in support to the rational design of HTF. In this context, the objective of this study was to propose an improvement in the model of turbidity removal efficiency developed by Oliveira (2014), which takes into account a set of geometric, hydraulic and hydrodynamic parameters relevant to the flocculation process in this type of reactor, by incorporating one of the most representative parameters of flocculation processes, the normal pressure gradient, as one of its independent variables. The development of the work employs computational fluid dynamics (CFD) in the study of 84 HTFs configurations, considering laminar and turbulent flow regimes. As a result, a new model version for estimating water turbidity removal’s efficiency in helical tubular flocculators was obtained, which, in relation to the original version, has a smaller number of independent variables, presents better fit to the experimental data and is simpler from the operational point of view.