 
		 
		 
		Diagram from sewage treatment plan for Philadelphia, 1912
 
		Southwest Sewage Treatment Plant under construction, 1949
 
		Emscher Tank Installation at Essen Nord, Germany
 
		Thomas Run sewer outlet at Cobbs Creek
 
		Thomas Run sewer outlet during construction
 
		Cohocksink Sewer System outlet at Laurel Street
