240 IOWA ACADEMY OF SCIENCES. 



BACTERIOLOGICAL INVESTIGATION OF THE IOWA 

 STATE COLLEGE SEWAGE. 



L. R. WALKER. 

 INTRODUCTION. 



As an introduction to the consideration of the Iowa 

 State College sewage, the kinds of sewage, the necessity of 

 disposal, and several of the most important methods with 

 their merits and disadvantages will be discussed. 



It has been my object in the following paper to bring 

 together the data obtained from the bacteriological 

 analysis of the college sewage, including daily samples 

 from the effluent and weekly samples from the manhole 

 and tank. Together with this data are given the daily 

 temperatures of the air and of the sewage, at the time of 

 taking samples; also, the soil temperatures, which were 

 taken once a week. 



Besides this data it has seemed desirable to give the 

 methods employed in the determination of the number of 

 bacteria per cubic centimeter of the sewage. 



And lastly, a partial interpretation of the results 

 obtained, has been attempted, special attention having 

 been given to the percentage of gas producers present in 

 the manhole, tank, and effluent, and to the fluctuations, 

 during the different days and seasons, of the number of 

 bacteria per cubic centimeter in the samples from the 

 manhole, tank, and effluent. The determination of the 

 species of bacteria present in the sewage has not been 

 attempted, only incidentally. 



From a sanitary point of view there is no question of 

 more vital importance than the proper disposal of sewage. 

 The lack of such disposal brings a multitude of evils, 



