NOTES ON THE PURIFICATION OF SEWAGE. 



XIX. 





IN PARTS 



PER MILLION. 





Average composition- 



-Raw Sewage. 



Effluent from 

 Cultivation 

 Chamber. 



Effluent from 

 Coke Filter. 



Effluent from 1 

 Coal Filter, i 



Total solids ... 



... 1088-33 



715 



728-75 



776-6 



Chlorine 



... 375- 



29666 



296- 



2933 



Free ammonia 



... 20-75 



40- 



26- 



29-3 



Albuminoid ammonia 8*775 



2-8 



2-12 



1-9 



Oxygen absorbed 



161 



11-716 



10-82 



1035 



Nitrous nitrogen 



... Oto-2 



trace 



•4 



•45 to 



Nitric nitrogen 



... 



trace 



2-5 



4-5 to 



PERCENTAGE OP IMPROVEMENT. 



Based on diminished quantity of 

 albuminoid ammonia. 



Based on diminished amount of 

 oxygen consumed. 



Coal Filters. 



Coke Filters. 



Coal Filters. 



Coke Filters. 



76% 



71% 



72-5% 



78-5% 



An effluent taken from one of the coke niters on the 18th April 

 was examined on the 8th of May and found to be free from any 

 unpleasantness whatever. 



As stated previously, the coal filter took 1 hour 42J minutes, 

 and the coke filter 2 hours 13^ minutes to fill, or a mean of 1 hour 

 •58 minutes. Had all the filters been of coke, the rate of flow 

 necessary to fill the filter in two hours would be 7,470 gallons per 

 twenty-four hours, which means that the tanks would deal with 

 the sewage from 178 persons instead of 160 for which they were 

 ■designed. 



The tanks had not been long in operation before it was found 

 that with a 4 inch diameter valve, the opening required for the 

 necessary rate of flow was too restricted and chokages were of 

 frequent occurrence. Then again the rate of flow varied accord- 

 ing to the rise or fall of the sewage in the carrier. It was there- 

 fore decided, in order to bring the installation into line with 

 ordinary working conditions, to introduce a flow regulator. This 

 regulator was inserted in a brick pit between the main carrier and 

 the tanks, and consisted of a conical valve actuated by a float, 

 which, as soon as the sewage attempted to rise in the pit, raised 



