GENERAL PAPERS 31 



PURIFICATION OF SEWAGE BY AERATION IN 

 THE PRESENCE OF ACTIVATED SLUDGE 



Edward Bartow, Sanitation Service, France 



abstract 



By blowing air into sewage, then allowing the suspended 

 matter to settle and decanting the supernatant liquid, adding 

 fresh sewage and repeating the operation, there is accumulated 

 sludge which has the property of purifying sewage in the pres- 

 ence of air in from four to five hours. The sludge obtained 

 contains more nitrogen than sludge obtained by any other 

 method of sewage purification. It has been shown by analyses 

 and by experiments with growing plants that it is valuable as 

 a fertilizer. By the process bacterial reduction of 95 to 99 per 

 cent is affected. The cost of the process depends upon the 

 cost of producing air. It has been estimated that it will be 

 the most effective and most economical method of sewage 

 purification. This will be especially true if the sludge can be 

 readily recovered and disposed of for use as a fertilizer. 

 Plants of considerable size have been constructed at Milwau- 

 kee, Cleveland and Champaign, and the process will be given 

 a thorough trial. 



Complete paper published in the Journal of the Boston So- 

 ciety of Civil Engineers, Vol. 3, No. 4, April, 1916, under the 

 title, "The Latest Method of Sewage Treatment." 



TESTS ON THE COMPARATIVE FRIABILITY OF 

 ILLINOIS COALS AND THEIR PRAC- 

 TICAL APPLICATION 



ABSTRACT 



L. A. Mylins, University of Illinois 



problem 

 The comparative friability of Illinois coals refers to the 

 comparative tendency among them to produce fines or break- 

 age or degradation products under like conditions. In mining 

 and marketing coal the excessive handling needed shatters 

 some coals more than others. Commercially this is of great 

 importance, since in general a reduction in size or an increase 



