Dynamic behavior of ozonation with pollutant in a countercurrent bubble column with oxygen mass transfer
Resource
Water Research 37 (11): 2583-2594
Journal
Water Research
Journal Volume
37
Journal Issue
11
Pages
2583-2594
Date Issued
2003
Date
2003
Author(s)
Abstract
The dynamic behavior of ozonation with pollutants in a countercurrent bubble column is studied for the model establishment. Bubble columns have been widely used for an ozonation system in the plants and laboratories. In addition, a countercurrent bubble column has been commonly recommended than a cocurrent one because it has a higher ozone transfer efficiency. Therefore, the investigation of this paper focuses on the countercurrent bubble column. As an ozonation process starts, the gas mixture of ozone and oxygen is introduced into the bottom of a column, and then transferred into the liquid. The pollutants in the wastewater are eliminated subsequently via oxidation by the dissolved ozone. There certainly exists a temporary and unsteady period before the ozonation system reaches steady state. However, available ozonation models employed to describe ozone and pollutant profiles have commonly been developed for steady state. The treating qualities of wastewater in the early stage of ozonation are usually not predicted, and the time required for the steady-state establishment remains to be determined. Moreover, oxygen mass transfer is usually neglected in previous ozonation models so that the increase of dissolved oxygen is uncertain. These information is desirable for the proper design and operation of ozonation system in a bubble column. Thus, the aim of this study is to model and investigate the dynamic processes of ozonation with pollutants including oxygen mass transfer. The dynamic axial dispersion model proposed is employed to predict the variation of the ozone, pollutant, and oxygen concentrations profiles. The validity of the model was demonstrated by comparing the predicted results with the experimental data. The o-cresol was chosen as the model pollutant. The temporal concentration variations of the residual o-cresol and dissolved oxygen in the effluent liquid, and the off-gas ozone in the free volume were measured accordingly. Furthermore, the variation of the enhancement factor of ozone and the amount of off-gas were predicted. Note that it usually needs 2-5 hydraulic retention times to approach steady state under the conditions of this study. Further, the effects of dimensionless system parameters on the performance of the ozonation processes are examined. As a result, the proposed dynamic model of ozonation with pollutants is useful for proper prediction of the variables of an ozonation system in a countercurrent bubble column. © 2003 Elsevier Science Ltd. All rights reserved.
SDGs
Other Subjects
Bubbles (in fluids); Data reduction; Mass transfer; Ozone; Water pollution; Ozonation systems; Wastewater treatment; ortho cresol; oxygen; bubble column; dynamic modeling; Mass transfer; Oxygen; Ozonation; pollutant removal; Wastewater; article; bubble column reactor; concentration (parameters); countercurrent system; dissolution; effluent; gas; gas mixing; liquid; measurement; oxidation; ozonation; pollutant; pollution control; priority journal; theoretical model; validation process; waste water; waste water management
Type
journal article
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