 
		 
		 
		Volume of Sludge from 1,000,000 Gallons of Sewage
 
		Diagram Showing Rate Between Bulk of Wet Sludge and Its Percentage Moisture
 
		Sludge Drying Beds, Essen Nord, Germany
 
		Grit Chamber, Essen, Germany
 
		Effects of Expansion of Gas Bubbles in Enscher Sludge Shown in Right-Hand Cylinder
 
		Sludge Presses for Grease Recovery, Bradford, England
 
		Drain water from sludges obtained from sedimentation, septic and Emscher tanks
 
		Diagram Showing Decreased Amount of Dissolved Oxygen in Delaware River, 1913
 
		Thomas Run sewer outlet at Cobbs Creek
 
		Thomas Run sewer outlet during construction
