Sewage and Sewage Effluents. 



191 



Such high efficiencies as these two tables indicate can 

 scarcely be expected even with the sand process under 

 the actual working conditions of a municipal plant. At 

 Vineland, N. J., for example, the intermittent niters show 

 a reduction of 90 to 95 per cent in total bacteria and a 

 somewhat higher reduction of B. coli. The results of 

 three examinations made in 1906 are given below. 



BACTERIA IN SEWAGE AND SAND FILTER EFFLUENT 

 AT VINELAND, N. J. 



(N. J. STATE SEWERAGE COMMISSION, 1907.) 



At Columbus the experimental sand niters effected an 

 average reduction of 87 per cent in total bacteria and of 

 98.5 per cent in colon bacilli. The number of B. coli 

 remaining in the effluent varied from 500 to 10,000 per 

 c.c. (Johnson, 1905). 



