Biological Sewage Disposal 249 



economics, convenience, and general cleanliness. Uncovered gar- 

 bage attracts flies and serves as a breeding ground for rats. While 

 insects and rodents probably pick up relatively few pathogenic 

 organisms from the garbage itself, large numbers of insects and 

 small animals can become an acute nuisance and a definite poten- 

 tial health hazard, since they are natural vectors of many microbes. 

 Under the same heading as garbage, we must think of other 

 solid waste material from human habitations not carried through 

 sewage systems. The general term "refuse" is applied to these 

 wastes, and includes ashes, rubbish, street sweepings, and dead 

 animals. In rural areas the disposal of refuse is a relatively simple 

 problem handled by individual families, but in large communities 

 the problem becomes magnified. The choice of available systems 

 depends upon local conditions, with economical sanitation an im- 

 portant consideration. A few common practices are listed below. 



DUMPING 

 Towing garbage out to sea has been a routine procedure for a 

 number of years in coastal areas, but since tides are capable of 

 carrying the unsightly material back to the shore, the practice has 

 been abandoned in many communities. There is little doubt that 

 dumping garbage out to sea is an economical means of disposal, 

 but other factors outweigh the advantages in many instances. 



FILLING 



Dry refuse can be used as fill for lowlands, but the dust prob- 

 lem on windy days can create very undesirable conditions, par- 

 ticularly if the prevailing wind carries the material back over the 

 city. Combustible trash is always a potential fire hazard, and the 

 number of times that the fire department is called to fight dump 

 fires during dry weather is sufficient evidence of the undesirability 

 of this disposal technic. 



BURIAL 



Deep trenches can be dug and covered with soil after organic 

 refuse has been dumped into these pits. Proper coverage to 

 prevent a rat and fly problem is necessary. 



