Membrane contactors ozonation

In particular, liquid-liquid extractions, wastewater treatments, gas absorption and stripping, membrane, and osmotic distillation, are the processes more studied. For example, the VOCs removal, the extraction of aroma compounds and metal ions, the concentration of aqueous solutions, the acid-gases removal, the bubble-free oxygenation/ozonation, have been successfully carried out by using membrane contactors [1, 2]. 

Membrane contactors can be effectively used also for disinfection purposes (e.g., water ozonation) [28] or for the oxidation of species present into water, for example, arsenic. Although the content of arsenic in seawater is today within the accepted limits, it is foreseen that in the future its concentration could increase, due to the increase of pollution of rivers and groundwaters. Usually, arsenic is contained in water as As(III) and As(V) forms, in different amounts. All arsenic-removal technologies have a better performance when arsenic is present in the pentavalent... 

Infusion of ozone into ultrapure water has become an excellent application of membrane contactors, as mentioned earlier. Ozone is generated in gas phase from air or oxygen, and the ozone-containing gas and ultrapure water are brought in contact with each other in the membrane contactor [50]. 

Wikol MJ, Kobayashi M, and Hardwick SJ, Application of PTFE membrane contactors to the infusion of ozone into ultra-high purity water. The ICCS 14th International Symposium on Contamination Control, Phoenix, AZ, April 26-May 1, 1998. 

Phattaranawik J, Leiknes T, and Pronk W. Mass transfer smdies in flat sheet membrane contactor with ozonation. J. Membr. Sci. 2005 247 153-167. 

Patents on new module designs have been recently presented. Nitto Denko (Japan) patented a spiral wound design for membrane contactor applications [51]. The system includes a central feed pipe around which one or more membranes are wound. Tests on water ozonation demonstrated that it is possible to achieve a concentrahon of ozone 10% higher than in hollow hber. 

Chan WK, Jouet J, Heng S, Yeung K-L, Schrotter J-C. Membrane contactor/separator for an advanced ozone membrane reactor for treatment of recalcitrant organic pollutants in water. J Solid State Chem 2012 189 96-100. 

Disinfection. Ozone is a more effective broad-spectmm disinfectant than chlorine-based compounds (105). Ozone is very effective against bacteria because even concentrations as low as 0.01 ppm are toxic to bacteria. Whereas disinfection of bacteria by chlorine involves the diffusion of HOGl through the ceU membrane, disinfection by ozone occurs with the lysing (ie, mpture) of the ceU wall. The disinfection rate depends on the type of organism and is affected by ozone concentration, temperature (106), pH, turbidity, clumping of organisms, oxidizable substances, and the type of contactor employed (107). The presence of oxidizable substances in ordinary water can retard disinfection until the initial ozone demand is satisfied, at which point rapid disinfection is observed. 

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