32 



SEWAGE-POLLUTED OYSTEES AS CAUSE OF TYPHOID. 



pound of slacked lime to 2,500 gallons of raw sewage. Four-ounce 

 samples of sewage, one collected before and one after treatment, were 

 examined, with the following result : 



Examination of seivage samples before and after treatment. 



Determinations. 



Before 

 treatment. 



After 

 treatment. 



Parts per million. 



Chemical analyses: i 



Ammonia 



Nitrogen as nitrites . . , 

 Nitrogen as nitrates . . , 

 Chlorin 



Bacteriological analyses: 

 On plain agar at 25° C 

 On plain agar at 37° C 

 B. coli 



Organisms per ec. 



7,100,000 



3, 700, 000 



10, 000 



4, 900, 000 



4, 000, 000 



10,000 



1 Chemical analyses made by W. W. Skinner, Water Laboratory, Miscellaneous Division, who comments 

 as follows: *' In the case of sewage, the results of the analysis show this to be probably a raw product, both 

 before and after treatment. But the examination, so far as made, seems to indicate that the treatment 

 has little effect upon the character of the material." Owing to the small amount of the sample, it was 

 impossible to make further chemical analyses. 



The bacteriological results show that one sample of sewage at the 

 time of collection contained more bacteria at 25° C. before treatment 

 than after treatment; however, the sample after treatment with lime 

 contained a higher total number of organisms at 37° C. The number 

 of B. coli was unchanged. 



The results, both chemically and bacteriologically, would indicate 

 practically no change resulting from treatment of this sewage at this 

 disposal plant. It was said that in addition to the lime used there 

 was also about 50 gallons of crude phenol used per month in washing 

 down the walls of the sediraentation basins during cleaning. 



In the accompanying illustration is shown the disposal plant in the 

 background, \yith the flume some 26 feet wide in the foreground. 

 The flume is reenforced with crossbeams, which cause its peculiar 

 appearance (see fig. 6). 



Besides the Hendrix Street disposal plant, the Jamaica and Far 

 Rockaway plants are operated in a similar manner; the output, 

 howeyer, is only a few million gallons daily. 



The Paerdegat sewer, haying a daily discharge of about 2,000,000 

 gallons, empties into Jamaica Bay, a short distance to the west of 

 Indian Creek, where nine oj^ster dealers, including dealer A, float 

 their oj^sters. To the east of the mouth of Indian Creek empty the 

 18,000,000 gallons of sewage from the Hendrix Street sewer (see ^g. 6). 



In addition to the effluent from the public trunk sewage systems of 

 Brooklyn and yicinity, there 3xe numerous small sewers located all 



