5 The Ozonation of Cyanide Wastes
:-^l :''-   '"":¦-'¦¦'^'¦^''¦     ¦¦¦''     ' ¦-'¦¦"¦¦.'.¦¦ V.-
,^;.'..     ,,;! _ RICHARD  G.   TYLER ',;    ;''. : v. , .
•;.'¦'••;•;'¦•      Professor of Sanitary Engineering      '¦¦¦'¦¦ '.?.''::¦;-..
;.¦;:'     ' WILLIAM   MASKE,   WILLARD  MATTHEWS      • ';'   '
'.'"¦¦¦;,¦  ;_'i'^ .- AND   M.   J.   WESTIN ;'    ,    '?^--- i.'    '
,. Research Fellows
/, * ' ., University of Washington ',   ,¦       ''     '    -
¦   . ¦    Seattle, Washington 'j
This paper is presented as a progress report on research in the ozonation of cyanide wastes being carried on at the University of Wash¬ ington. It is believed that the work has proceeded far enough to indicate, in general, the effectiveness of ozone in the oxidation of this waste. Another reason for presenting this progress report at this time is that chlorine, which is now being used increasingly in the treatment of cyanide wastes, is becoming more scarce for peacetime usages as the Korean situation continues. If, as it appears possible, ozone can do the job adequately, it would have the advantage of not being affected by war priorities and so would be useful to industries wishing to do some¬ thing about their cyanide waste problems during the present emergency.
The methods now in use for treating cyanide wastes are acidification, chemical precipitation and chlorination. Each of these methods has its advantages and also some disadvantages. With acidification, care must be taken in the disposal of the highly toxic cyanide gas evolved during the process. Also, with the increasing attention that is being focused upon the problems of air pollution, this method is less likely to be used in the future except for locations not in populous areas. Chemical precipitation has its sludge problems and requires the attention usually essential to the successful application of this method to other industrial wastes. Chlorination has certain obvious advantages over the other treatments, but it too has some drawbacks. Accurate controls are re¬ quired to carry out the process and at the same time keep down the residual chlorine in the effluent to acceptable standards. Chlorine residual is as toxic to fish as is cyanide, so that it should be held within similar limits in the treated waste. In the state of Washington, this is an im¬ portant drawback to chlorination because fishing is important both as an industry and as a sport. Large chlorine dosages also increase the pH or acidity which may be troublesome under some conditions, as where
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