Mathematical Modeling of Double Filtration by Colloidal Theory with Study Water Containing Microcystis spp

Abstract Anthropic activities have been causing serious impacts in aquatic environments, deteriorating the quality of the waters. Superficial springs with excess of nutrients, rich in compounds of phosphor and nitrogen, may induce blooms of algae and cyanobacteria, hard to be removed in the treatment of water. Such microscopic particles, e.g. Microcystis spp., are named biocolloids. This work propose to apply the mathematical modelling by the extended colloidal XDLVO theory (Extended Derjarguin-Landau-Verwey-Overbeek) for coagulation and gravel upflow filtration (GUF) and sand downflow rapid filtration (SDRF) to the technology of double filtration applied to study water containing Microcystis spp. The XDLVO theory has been shown to be efficient at evaluating the behavior of the colloidal particles as a function of the separation distance, making apparent how the intermolecular and surface forces act: acid-base interaction (AB), Lifshitz-Vander Walls (vdW), double electric layer (DEL) and Born repulsion forces. Such forces that act in this colloidal system formed by Microcystis spp. were analyzed in terms of their mutual interaction and their interaction with porous environments in double filtration at the stable thermodynamic situations (pre-coagulation) and at unstabilized by the chemical coagulation. The raw water energetic barrier of repulsion and after the sand downflow rapid filtration gave an average decreasing of about 90% in absolute values.