Population equivalent

Population equivalent (PE) or unit per capita loading, or equivalent person (EP), is a parameter for characterizing industrial wastewaters. It essentially compares the polluting potential of an industry (in terms of biodegradable organic matter) with a population (or certain number of people), which would produce the same polluting load. In other words, it is the number expressing the ratio of the sum of the pollution load produced during 24 hours by industrial facilities and services to the individual pollution load in household sewage produced by one person in the same time. A value frequently used in the international literature for PE is 54 gram of BOD per person (or per capita or per inhabitant) per day. In Europe it is commonly cited as 60 gram of BOD per person per day. This refers to the amount of oxygen-demanding substances in waste water which will consume oxygen as it bio-degrades, usually as a result of bacterial activity.

For practical calculations, it was assumed that one unit equalled 54 grams of Biochemical oxygen demand (BOD) per 24 hours, when the United Nations defined the term in 1997. In Poland it is now assumed to be 60 grams per day, and this is also the case within the European Union, while in United States, a figure of 80 grams per day is normally used.

$PE={\dfrac {BOD\ load\ from\ industry\ \left[{\dfrac {kg}{day}}\right]}{0.060\ \left[{\dfrac {kg}{inhab\cdot day}}\right]}}$

The calculations assume that one person living in a normal house will produce 200 litres of effluent per day, and that will contain 60 grams of biochemically active material. Thus a family of four living in a normal house would be expected to produce 800 litres of effluent, containing 240 grams of biochemically active material. The values vary for other situations, and so in Ireland, one guest staying in a hotel would typically produce 250 litres of effluent with 75 grams of active material, and so would have a population equivalent of 1.25.

Population equivalents of wastewater from some industries

Type	Activity	BOD PE [inhab/(unit/d)]
Food	Canning (fruit/vegetables)	500
	Pea processing	85-400
	Tomato	50-185
	Carrot	160-390
	Potato	215-545
	Citrus fruit	55
	Chicken meat	70-1600
	Beef	20-600
	Fish	300-2300
	Sweets/candies	40-150
	Sugar cane	50
	Dairy (without cheese)	20-100
	Dairy (with cheese)	100-800
	Margarine	500
	Slaughter house	10-100
	Yeast production	21000
Confined animals breeding	Pigs	35-100
	Dairy cattle (milking room)	1-2
	Cattle	65-150
	Horses	65-150
	Poultry	15-20
Sugar-alcohol	Alcohol distillation	4000
Drinks	Brewery	150-350
	Soft drinks	50-100
	Wine	5
Textiles	Cotton	2800
	Wool	5600
	Rayon	550
	Nylon	800
	Polyester	3700
	Wool washing	2000-4500
	Dyeing	2000-3500
	Textile bleaching	250-350
Leather and tanneries	Tanning	1000-3500
	Shoes	300
Pulp and paper	Pulp	600
	Paper	100-300
	Pulp and paper integrated	1000-10000
Chemical industrial	Paint	20
	Soap	1000
	Petroleum refinery	1
	PVC	200
Steelworks	Foundry	12-30
	Lamination	8-50

See also

• Sewage treatment

References

Sources

• Rowe, Donald R.; Abdel-Magid, Isam Mohammed (1995). Handbook of Wastewater Reclamation and Reuse. CRC Press. ISBN 978-0-87371-671-0.