206 



MICRO-ORGANISMS IN WATER 



Lime continued 



Original sewage 



Ditto after settling 1 hour without additions .... 

 Effluent with 1,000 lbs. of lime per 1 million gallons of sewage 

 1)200 „ ,, ,, ,, 



lj4:UU ,, )} ,, }, 



1,600 „ „ „ „ 



1,800 ,, „ ,, „ 



2,000 



Number of 



bacteria in 1 c.c 



. 1,572,000 



. 783,200 



55,200 



49,500 



44,000 



11,448 



12,300 



5,920 



Lime continned 



Number of 

 bacteria in 1 c.c. 



Original Sewage 1,364,000 



Ditto after settling 1 hour without additions .... 1,440,000 

 Effluent with 1,000 lbs. of lime per 1 million gallons of sewage 71,000 

 1,200 

 1,400 



1,600 

 1,800 

 2,000 



49,500 

 24,208 

 21,120 



7,884 

 1,484 



Copperas and lime. — In order to ascertain the value 

 of copperas, or ferrous sulphate, the following experi- 

 ments were conducted. As it had been found that the 

 best chemical results were obtained when lime was 

 used in conjunction with copperas, it was decided to 

 try to establish the right proportions in which these 

 materials should be added, and also to ascertain whether 

 it is more advantageous that the sewage should be first 

 mixed with the lime or the copperas respectively. 



Bacterial purification of Sewage with different quantities of Lime 



and Copperas 



Series A. — 500 Ihs. Copjperas with different amounts of Lime 



Number of 

 bacteria in 1 c.c. 



Origmal sewage . 176,000 



Ditto after settling 1 hour without additions .... 126,500 



lb. copperas 



Effluent with 500 per 1 million gallons of sewage . . . 24,500 



lb. lime 



,, and 200 per 1 million gallons of sewage . 56,000 



400 „ „ „ . 72,000 



800 „ „ „ . 56,000 



1,200 „ „ „ . 16,128 



2,000 ., „ , . 10,176 



