206 MICRO-ORGANISMS IN WATER 



Lime continued 



Number of 

 bacteria in 1 c.c 



Original sewage 1,572,000 



Ditto after settling 1 hour without additions .... 783,200 



Effluent with 1,000 Ibs. of lime per 1 million gallons of sewage 55,200 



1,200 49,500 



1,400 44,000 



1,600 11,448 



1,800 12,300 



2,000 5,920 



Lime continued 



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 Ibs. of lime per 1 million gallons of sewage 71,000 



1,200 49,500 



1,400 24,208 



1,600 21,120 



1,800 7,384 



2,000 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 Seioage with different quantities of Lime 



and Copperas 

 Series A. 500 Ibs. Copperas with different amounts of Lime 



Number of 

 bacteria in 1 c.c. 



Original sewage . 176,000 



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



lb. copiRTfis 



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



11). 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 



