144 Kansas Academy of Science. 



RELATION OF ALG^ TO WATER SUPPLIES. 

 In Massachusetts the work, including the surveys, carried on for the 

 State Board of Health by Calkins (5), Whipple (26) and others, has 

 shown the marked effect that heavy growths of certain genera of algae 

 have upon the usability of drinking water. In the first place, the water 

 is often given a very disagreeable odor. For a time this was thought to 

 be due only to the disintegration of the algae, but was later shown to be 

 caused also by the aromatic oils which are natural to certain species. 

 Some organisms may grow in great abundance without imparting any 

 odor whatsoever to the water, while others, though present in compara- 

 tively small quantities, render the water unfit for drinking purposes. 

 Whipple (26) has prepared a table, parts of which are copied below, 

 giving the natural odors of the three large classes of algse: 



Table I. 



Group. Organisms. Natural ndors. 



Aromatic odor Diatomacese Aromatic, geranium, fishy. 



Grassy odor Myxophycese Grassy, moldy, green-corn, nastur- 

 tium. SM'eet. 

 Fishy odor Chlorophycese Fishy. 



The odors of decomposition are usually more offensive than the nat- 

 ural odors. The Myxophyceae when decaying give a "pig-pen" odor, 

 Beggiotoa gives the odor of hydrogen sulphide or "rotten eggs," while 

 to some of the other genera the odor of garlic, onions, etc., is ascribed. 

 Water having these strong odors also has a very disagreeable taste. The 

 decaying vegetation often gives the water in addition a yellowish brown 

 color, making it unattractive and in some cases unfit for use even for 

 washing purposes. 



Besides this trouble with odors, tastes and color, the algal forms do 

 much damage in clogging the filters and decreasing the length of run 

 quite materially. The diatoms and other unicellular algae cause the most 

 trouble because of the dense mat which they are able to form over the 

 top of the sand. The filamentous algae, which grow erect upon the sand, 

 do not thus clog the filter, but on the contrary, they prevent clogging to 

 some extent by their waving threads. However, when these forms decay 

 they, too, settle to the bottom and block the filter. Another danger to 

 the filter is due to the release of gas by these plant forms which at times 

 is sufficient to cause great masses of the mat to rise, thus exposing the 

 sand so that the water filters through it much more rapidly than it should 

 to give efficient results in the tap water. 



The elimination of the algae from the filters can be accomplished by 

 covering them, since these plants can live only in the light. The eradi- 

 cation of the algae from the reservoirs was a problem, until Moore and 

 Kellerman (14) in 1905 issued a report stating their successful experi- 

 ments in the removal of algae by the use of copper sulphate. This treat- 

 ment has been in practice ever since and has proven to be entirely satis- 

 factory. The method of application as given in the above mentioned 

 paper is as follows: "Place the required number of pounds of copper 

 sulphate in a coarse bag — gunny sack, or some equally loose mesh — and 



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