Preliminary experiments have de- 

 monstrated that ozone generated by 

 this new apparatus can be added to 

 water satisfactorily and that objec- 

 tionable quantities of hydrogen per- 

 oxide and nitrous oxides are not de- 

 tected. 



In a second series of experiments, 

 pure cultures of bacteria likely to 

 be present in natural water were 

 suspended in sterile water, and 

 ozone was bubbled through the 

 suspensions. Plate counts made from 

 the suspensions before and after 

 they were treated with ozone de- 

 termined the amount of ozone and 

 the time of application required to 

 kill the bacteria. A very moderate 

 amount of ozone (two parts per mil- 

 lion) applied for one minute, killed 

 all bacteria except those that pro- 

 duce spores. Fortunately, bacteria 

 causing intestinal diseases^are not 

 spore producers. 



Disinfectants 



In a third set of experiments, two 

 parts per million of ozone, applied 

 for five minutes to raw water from 

 streams that contained bacteria from 

 natural sources, killed the bacteria. 

 A longer exposure time was required 

 because some of the bacteria were 

 spore-producers and because organic 

 matter in raw water combined with 

 and inactivated some of the ozone. 

 (Inactivation of disinfectants by or- 

 ganic matter is a recognized fact; 

 chlorine is inactivated in the same 

 way.) 



This new type ozonator, unlike earlier models, 

 can be installed and operated at a low cost. 



John H. Vondell 



Ozone More Effective 



In a final experiment, 15 parts 

 per million of ozone, applied for 

 three minutes, destroyed a culture 

 of protozoa that resisted the appli- 

 cation of 250 parts per million of 

 chlorine applied for a much longer 

 time. Ozone could be important in 

 eliminating from water supplies 

 pathogenic (disease-producing) pro- 

 tozoa such as those causing amoebic 

 dysentery. 



An inexpensive ozonating genera- 

 tor could be developed for the practi- 

 cal treatment of public water sup- 

 plies. Ozonation not only would 

 prevent tastes and odors so often 

 produced by chlorination, but would 

 effectively remove any tastes and 

 odors already in water before treat- 

 ment. 



The old order may change, then, 

 in water purification to give way to 

 the new in a more satisfactory and 

 effective substitute — ozone. 



