Water and Wastewater Terms Beginning P

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

population equivalent

A means of expressing the strength of organic material in wastewater. In a domestic wastewater system, microorganisms use up about 0.2 pound (90 grams) of oxygen per day for each person using the system (as measured by the standard BOD test). May also be expressed as flow (100 gallons/person/day or 378 liters/person/day) or suspended solids (0.2 lb SS/person/day or 90 grams SS/person/day).

population equivalent [persons] = flow rate [m gal/d] x BOD [mg/L] x 8.34 [b/gal] / 0.2 [b/person . d] BOD

or

population equivalent [person] = flow rate [m³/d] x BOD [mg/L] x 10 [L/m³] / 90,000 [mg/person . d] BOD