4 8 12 16 



TIME, days 



4 8 12 16 



TIME, days 



2.4 - 



O 



m E 



1.6 - 



< 



0.8 - 



4 8 12 



TIME, days 



16 



Figure 2. Summarized graphs of the main links in self-purification. 

 Figures at the curves denote increasing concentrations. 



25 



