Changing the surface characteristics of the micro air flotation systems by the addition of cationic polymers in recirculating pressurized and its effect on the overall efficiency of the process

• Grant number: 13/23339-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2014
• End date: June 30, 2014
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Marco Antonio Penalva Reali
• Grantee: Gabrielle Migliato Marega
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The dissolved air flotation ( DAF) as a technique for high-efficiency pre - clarified water supply has been established for decades. Consequently there is a growing number of treatment stations being built in large scale worldwide. According to Schofield (2001 ) , at the beginning of the last decade there were several FAD units around the globe. This demand by DAF occurs as the dissolved air flotation is effective alternative for the treatment of potable water, thus being applied as one of the stages clarification of certain types of waters such as waters with high concentrations of algae or humic substances ( REALI , 1991 EDZWALD , 2011) .Despite recent advances in relation to knowledge of the fundamental aspects of the flotation water supply , important points of this process are still poorly understood. For example , the lack of experimental verification of the theory of collision between particle and flake when these have opposite charges . HAN and Kim (2007 ) and theoretical studies conducted in a bench scale showing that there is greater process efficiency in the DAF clarification of water where the particles and the air bubbles have opposite charges . Was measured zeta potential of microbubbles of air immersed in water study ( water supply ), showing that it is always negative , as the colloidal particles present in natural waters. To alter the number dasmicrobolhas natural air , these authors used in their studies NaCl , KCl , MgCl2 , CaCl2 and AlCl3 .Following similar line to that of the work and HAN KIM (2007 ) , but with the use of chemicals other than those used by them in this work is being proposed research involving the use of cationic polymers with a view to modify the surface charge of the microbubbles air so as to seek improved efficiency and possibly of the speed ( rate ) of water applied to DAF process for supplying containing algae in suspension. It is believed that the use of smaller dosages of cationic polymers ( high charge density ) near the saturation chamber pressurized recirculation system FAD will control the zeta potential of microbubbles of air slightly positive values , in order to increase the effectiveness of these microbubbles air collisions with flakes in the water to be treated by flotation , which commonly show ZP near zero , however slightly negative .If this hypothesis is confirmed, it can be expected fairly good practical results as regards not only increase the efficiency of the coagulated particles flotation with the application of lower dosages of primary coagulant , but also the possibility of obtaining situation in which it has aggregate formation " bubbles / flakes " with greater speeds upward , which would allow the use of higher values of exchange flotation units full scale. (AU)