I go 



Elements of Water Bacteriology. 



BACTERIA IN SEWAGE AND SAND FILTER EFFLUENTS 



AT LAWRENCE. 



(CLARK, 1906.) 



Bacteria per ex. 



Applied sewage 

 Filter i . . 

 Filter ■> . . . 

 Filter 4 

 Filter sB 



Filter sC 

 Filter 6 . 

 Filter 9A 

 Filter 10 . 



2,906 



10,896 



4,585 



1.743 



The Septic Tank and Intermittent Sand Filter at Iowa 

 State College gave the following bacterial results in 1899 

 and 1900, the averages representing daily examinations 

 of the sand efHuent and weekly examinations of crude 

 and septic sewage. 



BACTERIA IN SEWAGE SEPTIC EFFLUENT AND SAND 



FILTER EFFLUENT AT IOWA STATE COLLEGE. 



(WALKER, 1901.) 



