Ceramic membranes ozonation

Janknecht P, Wilderer PA, Picard C, and Larbot A. Ozone-water contacting by ceramic membranes. Sep. Purif. Technol. 2001 25 341-346. 

Moulin et al. [64] use a coagulant and ozone to enhance the flux of their 0.2 pm ceramic membrane (Membralox). Using ozone and a concentration of 45 ppm coagulant, flux is approximately 15001/m h, with 110 ppm coagulant flux increases to 20001/m h. The ozone treatment decomposes the organic material, so fouling is kept at a minimum. 

Laboratory-scale bubble columns for ozonation preferably have a reactor liquid phase volume of VL = 2-10 L, with a height-to-diameter-ratio of hid = 5-10. The ozone/oxygen (ozone/air) gas mixture is supplied through a ceramic or stainless steel porous plate fine pore diffuser (porosity 3,10-40 pm hole diameter). PTFE-membranes are a comparatively new alternative for the ozone gas-to-water transfer (Gottschalk et al., 1998). 

Table 12 shows the typical LRV values obtained using a polymeric and ceramic microfilter. Sterile filtration requires 100% bacteria retention by the membrane, whereas in many industrial bacteria removal applications the presence of a small quantity of bacteria in the filtrate may be acceptable. For example, drinking water obtained by microfiltration may contain nominal counts of bacteria in the filtrate which is then treated with a disinfectant such as chlorine or ozone. The use of ceramic filters may allow the user to combine the sterile filtration with steam sterilization in a single operation. This process can be repeated many times without changing filters due to their long service life (5 years or longer). 

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