Andrzej K. Biń

Gas entrainment by plunging liquid jets

Abstract In this paper an extensive survey of the results of possibly all available experimental and theoretical studies on gas entrainment by plunging liquid jets has been presented. The following aspects of the phenomenon are thoroughly discussed: mechanisms, conditions of the onset of entrainment, amount of the entrained gas, characteristics of the resulting bubble dispersion (bubble size, depth of bubble penetration, gas holdup and bubble residence time) and mass transfer. Wherever possible, empirical correlations enabling estimation of the relevant quantities characterizing the entrainment phenomenon studied are given or recommended. Practical applications of the plunging jet aerator in waste treatment, fermentation and in the flotation industry are reviewed and its aeration (e.g. oxygenation) performance is compared with conventional aeration systems.

Hydrodynamics and ozone mass transfer in a tall bubble column

In the paper, major hydrodynamic parameters such as gas hold-up, phase velocities and axial dispersion as well as the ozone mass transfer coefficients in the liquid phase have been investigated in a tall bubble column for co-current, counter-current and semi-batch modes of operation. The major emphasis has been placed on evaluation of the dynamic characteristics of the combined system of experimental column and measuring sensors, which was applied in the subsequent determination of the axial dispersion and ozone mass transfer coefficients in the liquid phase. The ozone mass transfer coefficients have been estimated using two treatment methods of the recorded changes of ozone concentration in the liquid and gas phases with time during ozone absorption or stripping to an inert gas.

Ozone Solubility in Liquids

A comprehensive and critical survey of the available data on ozone solubility in different liquids—in water and aqueous solutions, as well as in organic solvents has been made. Apart of comparing the data published by the various authors after 1981 for water and aqueous solutions, special attention has been paid to the effects of pH and the composition of the liquid phase (salt effect). The published data on ozone solubility in organic liquids have been compiled and the listing of such data given by Battino (1981) has been supplemented by the more recent ones. Special interest has been given to perfluorinated organic solvents, which exhibit high solubility for both oxygen and ozone. More formal thermodynamic approach has also been attempted. Special attention has then been paid to the predictive methods developed for oxygen solubility in non-polar and polar solvents. This paper is presented in order to start a discussion on the very important, but very complicated, issue of ozone solubility. It is hoped this these discussions will lead to a special workshop on ozone solubility at the next Ozone World Congress.

Performance of confined plunging liquid jet bubble column as a gas–liquid reactor

The volumetric mass transfer coefficient in a confined plunging liquid jet (CPLJ) bubble column absorber was determined during a steady-state absorption of CO 2 in sodium carbonate and bicarbonate solution with an addition of hypochlorite catalyst. Special care was paid while choosing the suitable reaction rate to account for the two different zones in the absorber (mixing zone and pipe flow zone) where the volumetric mass transfer coefficients differ by an order of magnitude. The determined mass transfer coefficients reached 0.6 s -1 and appeared to be 50% lower than those determined during physical absorption of CO 2 . Energetic efficiency of the examined CPLJ contactor was also calculated.

Comparison of the Advanced Oxidation Processes (UV, UV/H2O2 and O3) for the Removal of Antibiotic Substances during Wastewater Treatment

The effectiveness of UV-based processes (UV and UV/H2O2) for the treatment of pharmaceuticals wastewater was investigated and compared with the effects of simple ozonation. Degradation of the studied antibiotic wastewater by direct photolysis indicated that, without application of additional factors, the process is not very effective, transferring the fate of antibiotics to the environment. For the studied antibiotic, wastewater ozonation was found to be the most effective among the three tested AOPs.

Minimum air entrainment velocity of vertical plunging liquid jets

Abstract Air entrainment by vertical liquid plunging jets is considered. Mechanisms leading to the onset of entrainment are briefly discussed. New experimental data are collected for the two regions of the onset of entrainment: droplet and continuous jet regions. For the droplet region of entrainment an empirical correlation is obtained. It is shown that there is some correspondence between the break-up length of jets and the limiting value of L j for entrainment in this region. For the continuous jet region turbulence intensity is one of the main factors which influence the values of V e . Some analogies with plunging solid tapes and rotating rollers are also pointed out.

Degradation of Nitroaromatics (MNT, DNT AND TNT) by AOPs

Abstract Application of selected AOPs to degrade nitroaromatics (nitrotoluene, dinitrotoluene and trinitrotoluene) in wastewater discharged from the production of TNT has been investigated. The first stage of the experiments was devoted to test the extent of degradation and improvement in biodegradation of the pure nitroaromatics using different AOPs: ozone alone, O3 + H2O2, O3+ UV, and Fenton reaction (Fe2+ + H2O2) at the various experimental conditions (pH, ozone concentration in the inlet gas, presence of radical scavengers). In the second stage degradation of the industrial wastewaters has been examined. Simple ozonation and the Fenton oxidation process were found to be the most effective.

Application Of A Single-Bubble Model In Estimation Of Ozone Transfer Efficiency In Water

Abstract A single-bubble model of mass transfer in gas-liquid systems enables the estimation of transfer efficiencies under different process conditions. In particular, it can be applied to simulate the effects of bubble size, value of the mass transfer coefficient, kinetics of reactions taking place in water and depth of the contact chamber. The results of such modelling in terms of transfer efficiency are presented for physical and chemical absorption of ozone in water at different hydrodynamic conditions (bubble size, water temperature, water depth in the contact chamber, and initial ozone concentration in the bubbles). The results of computations are compared with some reference data on ozone absorption in water in industrial-scale contact chambers.

Comments on “Decay of Ozone in Water: A Review” by D. Gardoni, A. Vailati, and R. Canziani (Ozone: Science & Engineering, 34(4): 233–242)

Recently, Gardoni et al. (2012) have offered a review of references devoted to ozone decomposition in water (or rather aqueous systems). They declared “to recapitulate the main results described in the literature” by considering a selection of 33 references (cf. Table 1, Gardoni et al. 2012) regarded by them as the main results available in the literature on that topic and published since 1913. I would like to make some comments on the authors’ presentation.

Modeling of Ozone Reaction with Benzaldehyde Incorporating Ozone Decomposition in Aqueous Solutions

Ozonation of benzaldehyde in its aqueous solutions based on mechanistic approach and incorporating ozone decomposition model is presented in this work. As the basis the modified and extended HSB model of ozone decomposition with phosphates and carbonates reactions included has been applied. It was then tuned with the literature data and the results of our own measurements on ozone decay in aqueous solutions. The model was extended to model benzaldehyde oxidation reactions in the aqueous solutions. Model predictions compare favorably against experimental data obtained in the range of pH 2.3 to 8 with or without radical scavenger (t-butanol).