CHAPTER 12 



Biological Sewage Disposal 



GENERAL CONSIDERATIONS 



TYPES OF SEWAGE DISPOSAL SYSTEMS 



Sanitary pit privies 

 Cesspools 

 Septic tanks 

 Imhoff tanks 

 Contact beds 

 Trickling filters 

 Sand beds 

 Activated sludge 



DISEASES POTENTIALLY TRANSMISSIBLE THROUGH SEWAGE 



GARBAGE AND OTHER WASTES 



GENERAL CONSIDERATIONS 



As important as the problem is of obtaining an adequate safe 

 supply of water for a community, a greater challenge, at least in 

 some areas, presents itself when sanitary engineers are faced with 

 the disposal of used water, which becomes sewage. We can 

 define sewage in a number of ways, but the term is usually ac- 

 cepted to mean the used water supply of a household or of a 

 community. It is a complicated mixture, both biologically and 

 chemically. If large volumes of chemical industrial wastes are in- 

 volved, fewer bacteria and more chemicals would be present than 

 if the sewage were composed principally of household wastes. But 

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