Abstract
This study evaluated the adjustment of four kinetic models and their respective parameters on data of dairy wastewater treatment by the physico-chemical process of flotation and ozonation. The experiment was implemented during the year 2014, with all the tests in triplicate. The treatments were carried out at different pH levels (3.6, 7.0 and 10.4), and flotation/ozonation was catalyzed by manganese (Mn2+) in neutral level (pH 7.0). Best removal efficiencies for chemical oxygen demand (COD) were obtained in acidic medium, with removals greater than 75% after 20 min of treatment. There was no significant difference with regards to addition of Mn2+on COD removal by the physico-chemical process. The kinetic models that best fit to the experimental data, for all treatments, were the asymptotic (residual) model and that of Chan and Chu. Treatment in acidic medium showed the highest values of the kinetic parameters for the adjusted model, obtaining a k coefficient equal to 0.2394 min-1for the asymptotic model and kinetic coefficient 1/ρ of 0.4816 min-1for the Chan and Chu model, both presenting a determination coefficient greater than 99%.
Highlights
Wastewater from the dairy industry contains high concentrations of nutrients and organic matter when compared to domestic wastewater (PRAZERES et al, 2012)
Flotation is a process of wide application in the treatment of oily wastewater, as an alternative preliminary treatment in the dairy industry for the removal of fat from industrial wastewater, which can harm the functioning of the treatment system (METCALF; EDDY, 2015)
The objective of this study was to fit first-order kinetic mathematical models and estimate their respective kinetic parameters to describe the degradation of organic matter in synthetic dairy wastewater by flotation/ozonation
Summary
Wastewater from the dairy industry contains high concentrations of nutrients and organic matter when compared to domestic wastewater (PRAZERES et al, 2012). In recent decades, Advanced Oxidation Processes (AOPs) have been used as an alternative for the treatment of wastewaters from various processes (TRIPATHI et al, 2011; AVSAR et al, 2012; WU et al, 2012). In the case of the dairy industry, there has been an intensified use of flotation in recent years, either by dispersed or dissolved air (CARVALHO et al, 2018). Flotation is a process of wide application in the treatment of oily wastewater, as an alternative preliminary treatment in the dairy industry for the removal of fat from industrial wastewater, which can harm the functioning of the treatment system (METCALF; EDDY, 2015). There are already some published reports on flotation using ozone instead of atmospheric air to enhance the efficiency of the treatment systems (LEE et al, 2008; KIM et al, 2011)
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