A Single Tube Contactor for Testing Membrane Ozonation

Abstract

A membrane ozonation contactor was built to investigate ozonation using tubular membranes and inform computational fluid dynamics (CFD) studies. Non-porous tubular polydimethylsiloxane (PDMS) membranes of 1.0–3.2 mm inner diameter were tested at ozone gas concentrations of 110–200 g/m3 and liquid side velocities of 0.002–0.226 m/s. The dissolved ozone concentration could be adjusted to up to 14 mg O3/L and increased with decreasing membrane diameter and liquid side velocity. Experimental mass transfer coefficients and molar fluxes of ozone were 2.4 × 10−6 m/s and 1.1 × 10−5 mol/(m2 s), respectively, for the smallest membrane. CFD modelling could predict the final ozone concentrations but slightly overestimated mass transfer coefficients and molar fluxes of ozone. Model contaminant degradation experiments and UV light absorption measurements of ozonated water samples in both ozone (O3) and peroxone (H2O2/O3) reaction systems in pure water, river water, wastewater effluent, and solutions containing humic acid show that the contactor system can be used to generate information on the reactivity of ozone with different water matrices. Combining simple membrane contactors with CFD allows for prediction of ozonation performance under a variety of conditions, leading to improved bubble-less ozone systems for water treatment.

Catalytic Ozonation and Membrane Contactors—A Review Concerning Fouling Occurrence and Pollutant Removal

“…When compared to fluoropolymers, PDMS is less resistant towards oxidizers other than ozone, including UV; however, its longer-term use in water treatment ozonation applications is still pending. Due to its availability in various sizes and relatively lower cost, PDMS is considered an appropriate "model" membrane material for smaller-scale investigations of coupled membrane/ozonation processes [11]. The resistance of polymers against ozone can be visually understood by the investigation of dos Santos et al [12], examining the resistance of various commercial polymeric membranes (PEI, PES, PP, PDMS, PVDF, PTFE) after contact with gaseous ozone.…”

“…The membranes that used as contactors in the ozonation processes must have three important attributes, i.e., (1) long-term stability to ozone exposure, (2) surface hydrophobicity, and (3) porosity [11]. The most membrane contactors are polymeric membranes, but the use of these materials in ozone-based processes is rather limited, due to the oxidation reactivity of ozone and the potential quick destruction of these membranes.…”

“…Except for their shape, ceramic membranes usually require appropriate surface modification before their use to increase hydrophobicity. Relevant studies have shown that the hydrophilic membranes present much lower efficiency as gas-liquid contactors than the hydrophobic ones [41], because the higher degree of hydrophobicity prevents the membrane's surface wetting and the flooding of pores [11]. The capillary forces in a hydrophilic membrane allow water to penetrate into its pores and may cause severe operational problems [41].…”

Catalytic Membrane Ozonation

“…As a consequence the use of common polymeric membrane contactors are quite limited [12]. It seems that only polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polydimethylsiloxane (PDMS) polymeric membranes are presenting sufficient resistance, when contacting with ozone [4,14]. Alternatively, ceramic membranes can be often selected [12].…”

Recent Advances in Water and Wastewater Treatment with Emphasis in Membrane Treatment Operations

“…Apart from the studies dealing with membrane treatment applications for water and wastewaters, in this special issue, some interesting research, examining other processes, such as ozonation, coagulation, and adsorption, were also included. In particular, in the work of Zoumpouli et al [10], entitled "A Single Tube Contactor for Testing Membrane Ozonation", a membrane ozonation contactor was built to investigate ozonation by using appropriate tubular membranes. Non-porous tubular poly(dimethylsiloxane) (PDMS) modified membranes of 1.0-3.2 mm inner diameter was tested at ozone gas concentrations of 110-200 g/m 3 and liquid side velocities of 0.002-0.226 m/s.…”