SEWAGE TREATMENT — KEEFER 



387 



Figure 8. — Flash drying and incineration system, Combustion Engineering, Inc. 



ash. Furnaces of this type are provided at Detroit, Cleveland, and 

 Minneapolis-St. Paul. 



The second type of incinerator combines flash-drying equipment 

 with facilities for conveying the dried product to the drying furnace, 

 where the material is incinerated. This type of incinerator is used 

 at Buffalo, N. Y., Washington, D. C. and Neenah-Menasha, Wis. 



COMBINATIONS OF SEWAGE-TREATMENT PROCESSES 



The foregoing sewage-treatment processes can be grouped in a num- 

 ber of ways. The processes that are selected depend upon several 

 factors. If the ratio of the volume of diluting water to the volume 

 of sewage is great, it may be that the removal of only the coarse sus- 

 pended materials is necessary. Should such be the case, fine screens 

 may suffice. Fine screens have been in service for many years at the 

 Canal Street plant and the Dyckman Street plant in New York City. 



Where a somewhat higher degree of treatment is required, sedimen- 

 tation tanks are generally provided. They are preceded by coarse 

 screens and also by grit chambers if the sewage is from a combined 

 system of sewers. The use of sedimentation tanks requires facilities 

 to treat and dispose of the sludge that is produced. Plants of this 

 type serve Buffalo, N. Y., Detroit, Mich., and Washington, D. C. 



