Ozone colour removal

Hung Y.S. (1995) Huang C.R. et al. (1994) tried to use ozone to decolour the dy-eing effluent containing Direct Black and Blue dyes. The author found that the efficienc y of colour removal was highest at neutral pH 6.45 but not at alkaline pH. Nevertheless, Carriere J. et al. (1991) concluded that the decolouration of some commercial dyes occurred faster at higher temperature and higher pH. 

Ozonation system consists of the following sections a. feed-gas treatment b. ozone generation c. ozone-water contact mechanism and d. destruction unit (Lin S.H., 1993). The use of ozonation in preliminary treatment is not economic effective even it can decrease the soluble organic. Therefore, it is better to implement Ozonation in tertiary treatment for effectively colour removal of the residual dyes. 

Tan L., Amy G.L. (1991), Comparing ozonation and membrane separation for colour removal and disinfection by-product control. Journal AWWA, May 91, 74-79. 

Ketone 13 is apparently sensitive to overoxidation and the reaction mixture must be cooled to -78 °C before ozone is bubbled through it. Ozone addition must be stopped immediately after the blue colour of the ozone-saturated solution is detected. Another potential side reaction is the condensation of benzaldehyde with diketone 12 this reaction can be induced by overheating a concentrated solution of the crude product mixture. Accordingly, the residue from rotary evaporation obtained in step 10 of Protocol 7 should not be heated above 45-50 °C before benzaldehyde is removed completely by exposure to high vacuum and trituration of the residue with diethyl ether. 

These pollutants are not removed by conventional methods of water treatment. The chlorination and the ozonization also is not always effective because is accompa-ined by formation of secondary compaunds, frequently harmful. Even the low concentration of these substances also influences organoleptic properties (taste, colour, odour) of water negatively and it is toxic and carcinogenic for human organisms. It was stated, that the removal of these substances from water may be achieved by means of adsorption on activated carbons [9—11 ]. 

To produce potable water which is safe to consume and free from turbidity, colour, odour and taste natural (raw) water abstracted from rivers, lakes, reservoirs and wells, etc., must be treated to remove pathogenic organisms, and mineral and organic contaminants. This is normally done by a process train comprising coagulation, flocculation, sedimentation and filtration followed by disinfection using either chlorine or ozone. 

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